1 00:00:11,540 --> 00:00:05,059 good morning or afternoon everyone this 2 00:00:14,660 --> 00:00:11,550 is carl at nai central and welcome to 3 00:00:18,680 --> 00:00:14,670 the latest in the director seminar 4 00:00:21,439 --> 00:00:18,690 series our speaker today is steve daunt 5 00:00:24,230 --> 00:00:21,449 from the university of rhode island p I 6 00:00:26,210 --> 00:00:24,240 of our alumni team and he is speaking to 7 00:00:28,970 --> 00:00:26,220 us from the Marine Biological Laboratory 8 00:00:30,710 --> 00:00:28,980 one of our current team so we have a 9 00:00:33,410 --> 00:00:30,720 little entertainment or action going on 10 00:00:37,310 --> 00:00:33,420 even real time during the seminar today 11 00:00:40,700 --> 00:00:37,320 it's a real pleasure to have Steve speak 12 00:00:42,470 --> 00:00:40,710 to us he is has been working on some 13 00:00:44,569 --> 00:00:42,480 very exciting things that we're going to 14 00:00:46,850 --> 00:00:44,579 hear about to give you a little bit of 15 00:00:49,250 --> 00:00:46,860 background on Steve he is a professor of 16 00:00:51,889 --> 00:00:49,260 Oceanography at the University of Rhode 17 00:00:54,470 --> 00:00:51,899 Island has a bachelor's in geology from 18 00:00:56,660 --> 00:00:54,480 Stanford and masters and PhD in 19 00:00:59,860 --> 00:00:56,670 geological and geophysical Sciences from 20 00:01:04,070 --> 00:00:59,870 Princeton University he has been working 21 00:01:06,200 --> 00:01:04,080 for some time on studying life in 22 00:01:10,310 --> 00:01:06,210 extreme environments particularly life 23 00:01:12,410 --> 00:01:10,320 in subsea floor sediments and biological 24 00:01:14,960 --> 00:01:12,420 controls on the chemical evolution of 25 00:01:18,770 --> 00:01:14,970 the ocean and atmosphere and he has 26 00:01:20,780 --> 00:01:18,780 written recently made a field expedition 27 00:01:23,149 --> 00:01:20,790 to the South Pacific Gyre which we're 28 00:01:25,550 --> 00:01:23,159 going to be hearing about today in a 29 00:01:28,160 --> 00:01:25,560 talk entitled microbial activities in 30 00:01:34,190 --> 00:01:28,170 deep sub seafloor sediments and Steve 31 00:01:36,620 --> 00:01:34,200 I'll turn it right over to you thank you 32 00:01:39,560 --> 00:01:36,630 very much Carl for the warm introduction 33 00:01:41,120 --> 00:01:39,570 and thank you for inviting me to have 34 00:01:45,319 --> 00:01:41,130 this opportunity to speak with all of 35 00:01:48,469 --> 00:01:45,329 our friends at nai again Carl has 36 00:01:50,630 --> 00:01:48,479 already read my title to you so i won't 37 00:01:52,370 --> 00:01:50,640 i won't repeat that the people i've 38 00:01:55,670 --> 00:01:52,380 listed as co-authors some of you will 39 00:01:58,359 --> 00:01:55,680 know as members of our team these are 40 00:02:00,289 --> 00:01:58,369 team members whose work as directly 41 00:02:02,539 --> 00:02:00,299 related to what i'm going to present 42 00:02:06,730 --> 00:02:02,549 today so this is a subset of the 43 00:02:09,760 --> 00:02:06,740 membership of our our nai alumni team 44 00:02:12,650 --> 00:02:09,770 the two images i've put up there are 45 00:02:13,790 --> 00:02:12,660 photographs of the two ships that we've 46 00:02:16,430 --> 00:02:13,800 used for most 47 00:02:19,850 --> 00:02:16,440 of our expeditions the lower photograph 48 00:02:21,790 --> 00:02:19,860 is a night photograph of the joy DS 49 00:02:27,670 --> 00:02:21,800 resolution the International drillship 50 00:02:30,680 --> 00:02:27,680 taken in San Diego harbor and the upper 51 00:02:36,260 --> 00:02:30,690 photograph is the Roger Revelle which is 52 00:02:38,900 --> 00:02:36,270 part of the University shared fleet of 53 00:02:40,340 --> 00:02:38,910 the United States there's ships in many 54 00:02:41,690 --> 00:02:40,350 different oceanographic institutions 55 00:02:45,320 --> 00:02:41,700 there's one at the University of Rhode 56 00:02:47,030 --> 00:02:45,330 Island there are a couple at Scripps 57 00:02:48,110 --> 00:02:47,040 plus some some other special things at 58 00:02:49,760 --> 00:02:48,120 Scripps and there are others scattered 59 00:02:52,250 --> 00:02:49,770 around the country this particular one 60 00:02:58,820 --> 00:02:52,260 is a script ship and we used it because 61 00:03:00,710 --> 00:02:58,830 we were working in the Pacific I'm going 62 00:03:03,230 --> 00:03:00,720 to start by drawing your attention to 63 00:03:04,910 --> 00:03:03,240 the blueness of the water there I hope 64 00:03:08,180 --> 00:03:04,920 that you all have rooms dark enough to 65 00:03:09,770 --> 00:03:08,190 see this this is a photograph of the 66 00:03:12,890 --> 00:03:09,780 surface ocean in the South Pacific Gyre 67 00:03:14,390 --> 00:03:12,900 it is the clearest water in the world 68 00:03:17,600 --> 00:03:14,400 the clearest natural water in the world 69 00:03:19,190 --> 00:03:17,610 the deep chlorophyll maximum there is a 70 00:03:22,810 --> 00:03:19,200 little over a hundred and sixty meters 71 00:03:25,880 --> 00:03:22,820 beneath the sea surface the water is a 72 00:03:28,729 --> 00:03:25,890 beautiful periwinkle blue that actually 73 00:03:29,960 --> 00:03:28,739 edges toward violet that's how clear the 74 00:03:31,160 --> 00:03:29,970 water is you're not going to see that 75 00:03:34,580 --> 00:03:31,170 color of water anywhere else in the 76 00:03:36,170 --> 00:03:34,590 world the topix I'm going to discuss 77 00:03:39,350 --> 00:03:36,180 today are listed against the backdrop of 78 00:03:41,750 --> 00:03:39,360 that water I'm going to discuss life in 79 00:03:43,880 --> 00:03:41,760 subsea flower sediments starting with a 80 00:03:48,290 --> 00:03:43,890 focus on biomass and moving on to 81 00:03:49,940 --> 00:03:48,300 activities and sort of categories of 82 00:03:52,010 --> 00:03:49,950 activities that are present then 83 00:03:55,070 --> 00:03:52,020 activity bracel a little bit about 84 00:03:57,770 --> 00:03:55,080 community activity then I'll focus on 85 00:03:59,479 --> 00:03:57,780 some examples of effects on the surface 86 00:04:01,520 --> 00:03:59,489 world which some of you can think of as 87 00:04:05,810 --> 00:04:01,530 potential bio signatures on a planetary 88 00:04:07,810 --> 00:04:05,820 scale and then I will close with a 89 00:04:10,310 --> 00:04:07,820 little bit of speculation about 90 00:04:18,320 --> 00:04:10,320 potential food sources for subsea floor 91 00:04:20,599 --> 00:04:18,330 life this first image here if you go 92 00:04:24,290 --> 00:04:20,609 down right there you see a glowing green 93 00:04:26,450 --> 00:04:24,300 dot that's a microbe from a couple 94 00:04:28,969 --> 00:04:26,460 hundred meters beneath the Arctic sea 95 00:04:32,360 --> 00:04:28,979 floor this particular sample was taken 96 00:04:34,790 --> 00:04:32,370 and photographed by David Smith who who 97 00:04:39,400 --> 00:04:34,800 was a member of our team the reason that 98 00:04:41,900 --> 00:04:39,410 dot is glowing green is that it is 99 00:04:44,090 --> 00:04:41,910 stained with cyber green which 100 00:04:47,360 --> 00:04:44,100 preferentially binds to DNA and then 101 00:04:54,770 --> 00:04:47,370 causes fluorescence so that is 102 00:05:02,160 --> 00:04:58,560 these little glowing yellow orange dots 103 00:05:04,820 --> 00:05:02,170 are from another cruise of ours in this 104 00:05:09,510 --> 00:05:04,830 case 320 meters beneath the sea floor in 105 00:05:11,370 --> 00:05:09,520 the equatorial Pacific and this is a 106 00:05:14,460 --> 00:05:11,380 figure from Axl shippers who's one of 107 00:05:16,290 --> 00:05:14,470 our clothes European collaborators these 108 00:05:20,130 --> 00:05:16,300 are stained with a different stain that 109 00:05:23,940 --> 00:05:20,140 binds to RNA and this particular stain 110 00:05:26,610 --> 00:05:23,950 is specific to bacterial RNA so what 111 00:05:29,250 --> 00:05:26,620 we're seeing here is that what would 112 00:05:31,650 --> 00:05:29,260 qualify as a glowing green dot is also a 113 00:05:34,320 --> 00:05:31,660 glowing yellow dot because there's 114 00:05:36,150 --> 00:05:34,330 enough RNA in it to flash which implies 115 00:05:40,610 --> 00:05:36,160 that this organism was recently active 116 00:05:47,790 --> 00:05:42,720 that's going to have some bearing on 117 00:05:51,060 --> 00:05:47,800 what we see next the standard estimate 118 00:05:54,360 --> 00:05:51,070 of life's subsurface biomass if you look 119 00:05:56,880 --> 00:05:54,370 up here you'll see that the standard 120 00:06:00,060 --> 00:05:56,890 estimate by Whitman and colleagues pnas 121 00:06:01,950 --> 00:06:00,070 1998 infers that ninety eight percent of 122 00:06:04,980 --> 00:06:01,960 life in the oceans lies beneath the sea 123 00:06:06,960 --> 00:06:04,990 floor in the sediments you contrast that 124 00:06:09,150 --> 00:06:06,970 with the continents here where we see 125 00:06:11,430 --> 00:06:09,160 about twenty percent is inferred to be 126 00:06:14,280 --> 00:06:11,440 beneath the surface of the continent and 127 00:06:16,230 --> 00:06:14,290 then the global estimate essentially 128 00:06:18,270 --> 00:06:16,240 infers that a little over a third of 129 00:06:20,820 --> 00:06:18,280 life on earth lies beneath the sea floor 130 00:06:23,340 --> 00:06:20,830 I mean beneath the beneath the surface 131 00:06:26,909 --> 00:06:23,350 of the world most of that is beneath the 132 00:06:28,260 --> 00:06:26,919 sea floor so the standard estimate is 133 00:06:30,270 --> 00:06:28,270 essentially that a third of life on 134 00:06:33,120 --> 00:06:30,280 earth lies beneath the sea floor that 135 00:06:35,310 --> 00:06:33,130 estimate is based on the data from this 136 00:06:37,980 --> 00:06:35,320 paper which is paper by john parks and 137 00:06:40,710 --> 00:06:37,990 his collaborators in 1994 where they 138 00:06:45,570 --> 00:06:40,720 presented cell counts from five ocean 139 00:06:47,610 --> 00:06:45,580 drilling program sites and set notice 140 00:06:49,560 --> 00:06:47,620 that they to a first approximation all 141 00:06:54,180 --> 00:06:49,570 had roughly similar numbers of cells at 142 00:06:55,950 --> 00:06:54,190 every depth so there's there's basically 143 00:06:57,510 --> 00:06:55,960 two assumptions being made then in 144 00:07:00,630 --> 00:06:57,520 Whitman's estimate the first assumption 145 00:07:03,000 --> 00:07:00,640 is that the body counts correspond to 146 00:07:04,529 --> 00:07:03,010 living biomass counts in other words 147 00:07:06,980 --> 00:07:04,539 that all of the bodies counted are alive 148 00:07:10,010 --> 00:07:06,990 and the second assumption is that the 149 00:07:15,980 --> 00:07:10,020 five sites a characteristic of the world 150 00:07:18,620 --> 00:07:15,990 as a whole the ocean as a whole we saw 151 00:07:20,780 --> 00:07:18,630 some clues in 2002 that they probably 152 00:07:23,660 --> 00:07:20,790 weren't characteristic of the ocean as a 153 00:07:26,060 --> 00:07:23,670 whole that standard estimate this is 154 00:07:27,980 --> 00:07:26,070 parks at all two thousand line but it's 155 00:07:30,080 --> 00:07:27,990 not radically different than their 1994 156 00:07:33,350 --> 00:07:30,090 line the cell counts from our cruise 157 00:07:34,820 --> 00:07:33,360 these sites in 2002 you see that as we 158 00:07:37,280 --> 00:07:34,830 move offshore into the equatorial 159 00:07:40,880 --> 00:07:37,290 Pacific which is still a nutrient-rich 160 00:07:44,300 --> 00:07:40,890 up blowing zone of the ocean as we move 161 00:07:46,370 --> 00:07:44,310 offshore the counts drop off so the 162 00:07:48,530 --> 00:07:46,380 average count seem to be characteristic 163 00:07:51,200 --> 00:07:48,540 of margin environments like we see here 164 00:07:54,830 --> 00:07:51,210 but perhaps not characteristic of the 165 00:07:57,800 --> 00:07:54,840 sea floor as a whole so let's move a 166 00:07:59,690 --> 00:07:57,810 little bit further into this this is 167 00:08:01,190 --> 00:07:59,700 data from axle shippers paper that I 168 00:08:03,650 --> 00:08:01,200 showed you the figure from a short while 169 00:08:05,660 --> 00:08:03,660 ago what you see here basically these 170 00:08:10,250 --> 00:08:05,670 are acridine orange direct counts like 171 00:08:11,990 --> 00:08:10,260 cyber green black reading orange is 172 00:08:15,320 --> 00:08:12,000 actually a more complex stain it binds 173 00:08:18,580 --> 00:08:15,330 to both DNA and RNA but to a first 174 00:08:21,740 --> 00:08:18,590 approximation since DNA is typically 175 00:08:23,540 --> 00:08:21,750 present long after RNA we can treat this 176 00:08:27,110 --> 00:08:23,550 as a measure of the cells that contain 177 00:08:29,680 --> 00:08:27,120 DNA and then this card fish stayin here 178 00:08:33,200 --> 00:08:29,690 this is the one that binds to RNA alone 179 00:08:36,440 --> 00:08:33,210 so what you see is that roughly ten 180 00:08:40,370 --> 00:08:36,450 percent of the cells on average that are 181 00:08:43,520 --> 00:08:40,380 counted with the DNA stain have enough 182 00:08:46,250 --> 00:08:43,530 RNA to flash with the RNA steam which 183 00:08:48,920 --> 00:08:46,260 suggests that on average approximately 184 00:08:51,640 --> 00:08:48,930 ten percent of the cells may be active 185 00:08:55,300 --> 00:08:51,650 and live now there the number that's 186 00:08:57,800 --> 00:08:55,310 alive maybe even greater than this but 187 00:08:59,840 --> 00:08:57,810 it sort of depends on where you draw the 188 00:09:01,700 --> 00:08:59,850 live dead boundary they don't have 189 00:09:03,860 --> 00:09:01,710 enough RNA for for excellent as 190 00:09:05,420 --> 00:09:03,870 collaborators to see but it's 191 00:09:07,310 --> 00:09:05,430 conceivable that something could be 192 00:09:10,460 --> 00:09:07,320 alive eking out an existence at some 193 00:09:12,080 --> 00:09:10,470 level that that we can't identify so the 194 00:09:15,140 --> 00:09:12,090 easiest way to interpret this is to say 195 00:09:16,580 --> 00:09:15,150 that conservatively about ten percent of 196 00:09:19,430 --> 00:09:16,590 the counted cells that those sites are 197 00:09:20,750 --> 00:09:19,440 alive and perhaps more alive you can see 198 00:09:22,490 --> 00:09:20,760 this has big implications 199 00:09:24,920 --> 00:09:22,500 for the amount of biomass on earth 200 00:09:27,080 --> 00:09:24,930 because it can pull down by an order of 201 00:09:32,180 --> 00:09:27,090 magnitude potentially estimates of 202 00:09:33,980 --> 00:09:32,190 subsea floor biomass okay now we're 203 00:09:36,290 --> 00:09:33,990 going to go to the South Pacific Gyre I 204 00:09:38,750 --> 00:09:36,300 just got back from there in early 205 00:09:41,960 --> 00:09:38,760 februari so you're seeing shipboard data 206 00:09:43,370 --> 00:09:41,970 these are counts by a former postdoc of 207 00:09:46,360 --> 00:09:43,380 are now a faculty member at the 208 00:09:49,700 --> 00:09:46,370 University of Potsdam yawns calm i er 209 00:09:53,390 --> 00:09:49,710 this is the ODP database that define the 210 00:09:55,250 --> 00:09:53,400 line we saw before this is a log-log 211 00:09:57,920 --> 00:09:55,260 scale incidentally all of these plots or 212 00:10:01,580 --> 00:09:57,930 log log scales and this is these black 213 00:10:05,860 --> 00:10:01,590 symbols are the data from our sites in 214 00:10:09,710 --> 00:10:05,870 this red box so this site right here 215 00:10:12,880 --> 00:10:09,720 comes closest to the ODP data that's 216 00:10:15,680 --> 00:10:12,890 located here on the northern edge of the 217 00:10:17,690 --> 00:10:15,690 Antarctic convergence zone which is a 218 00:10:19,430 --> 00:10:17,700 major upwelling zone so there's more 219 00:10:22,490 --> 00:10:19,440 organic matter raining down there than 220 00:10:24,170 --> 00:10:22,500 anywhere else here now where I told you 221 00:10:27,230 --> 00:10:24,180 is the clearest water in the world is 222 00:10:30,140 --> 00:10:27,240 right here at site seven this base map 223 00:10:32,120 --> 00:10:30,150 is a site of sea service chlorophyll so 224 00:10:34,220 --> 00:10:32,130 all of these green areas are upwelling 225 00:10:35,870 --> 00:10:34,230 areas then as you move to darker and 226 00:10:38,090 --> 00:10:35,880 darker colors we're moving to lower and 227 00:10:41,020 --> 00:10:38,100 lower chlorophyll concentrations the 228 00:10:45,020 --> 00:10:41,030 concentrations actually decrease here 229 00:10:48,020 --> 00:10:45,030 this is essentially grams per square 230 00:10:52,520 --> 00:10:48,030 meter of sea surface and our range here 231 00:10:56,840 --> 00:10:52,530 is from 10 to 0 point 0 1 so they're 232 00:10:59,420 --> 00:10:56,850 ranging over four orders of magnitude 233 00:11:02,450 --> 00:10:59,430 and what we're seeing here is at the 234 00:11:04,910 --> 00:11:02,460 point zero one end what you see up here 235 00:11:06,290 --> 00:11:04,920 at that little tiny red areas at the ten 236 00:11:08,900 --> 00:11:06,300 end and what you see in these green 237 00:11:10,880 --> 00:11:08,910 areas is the one end or in the middle of 238 00:11:13,610 --> 00:11:10,890 one so what we're seeing is that 239 00:11:16,520 --> 00:11:13,620 everywhere in this red box falls over 240 00:11:20,000 --> 00:11:16,530 here with three orders of magnitude 241 00:11:23,270 --> 00:11:20,010 fewer cells than the average for all the 242 00:11:25,370 --> 00:11:23,280 previously counted sites so what's this 243 00:11:28,010 --> 00:11:25,380 telling us this is telling us that the 244 00:11:29,810 --> 00:11:28,020 standard estimate relied on sites that 245 00:11:31,820 --> 00:11:29,820 are in fact not characteristic of the 246 00:11:33,850 --> 00:11:31,830 sea floor as a whole and then for all 247 00:11:37,060 --> 00:11:33,860 practical purposes 248 00:11:40,480 --> 00:11:37,070 anywhere in the turquoise through black 249 00:11:43,030 --> 00:11:40,490 zone here has three orders of magnitude 250 00:11:46,420 --> 00:11:43,040 fewer cells than Whitman assume the sea 251 00:11:49,900 --> 00:11:46,430 floor to hold per cubic centimeter back 252 00:11:51,519 --> 00:11:49,910 up a little more when you look at the 253 00:11:54,370 --> 00:11:51,529 ocean as a whole you see that in fact 254 00:11:59,560 --> 00:11:54,380 most of the ocean is in that range of 255 00:12:02,470 --> 00:11:59,570 turquoise through dark blue so 256 00:12:06,069 --> 00:12:02,480 effectively then the vast majority of 257 00:12:08,380 --> 00:12:06,079 the sea floor has somewhere in the 258 00:12:10,630 --> 00:12:08,390 ballpark of a thousand to ten thousand 259 00:12:11,889 --> 00:12:10,640 cells per cubic centimeter I shouldn't 260 00:12:12,940 --> 00:12:11,899 say the sea the sea floor actually has 261 00:12:14,829 --> 00:12:12,950 about a million cells per cubic 262 00:12:16,810 --> 00:12:14,839 centimeter as opposed to a billion and 263 00:12:19,030 --> 00:12:16,820 then once you're down in the subsurface 264 00:12:20,380 --> 00:12:19,040 you're looking at about a thousand to 265 00:12:22,540 --> 00:12:20,390 ten thousand cells per cubic centimeter 266 00:12:26,050 --> 00:12:22,550 instead of the million or so that 267 00:12:28,120 --> 00:12:26,060 Whitman assumed so setting aside the 268 00:12:32,680 --> 00:12:28,130 issue of whether the the bodies are live 269 00:12:34,810 --> 00:12:32,690 or dead what you see is that the size of 270 00:12:37,210 --> 00:12:34,820 the subsurface biomass on earth is 271 00:12:41,680 --> 00:12:37,220 actually far lower than the standard 272 00:12:42,759 --> 00:12:41,690 estimate but don't lose heart because as 273 00:12:49,689 --> 00:12:42,769 we'll see later in this presentation 274 00:12:52,090 --> 00:12:49,699 they still get to matter so I'm going to 275 00:12:58,120 --> 00:12:52,100 speak about rates about kinds and rates 276 00:13:00,639 --> 00:12:58,130 of activities now very very briefly it's 277 00:13:03,280 --> 00:13:00,649 been a lot of work in the last few years 278 00:13:07,569 --> 00:13:03,290 looking at microbial processes in subsea 279 00:13:10,660 --> 00:13:07,579 floor sediments so we now know that a 280 00:13:13,210 --> 00:13:10,670 lot of classic microbial reactions occur 281 00:13:15,400 --> 00:13:13,220 in the subsea floor many of which were 282 00:13:18,069 --> 00:13:15,410 known to occur in shallow marine 283 00:13:20,769 --> 00:13:18,079 sediments in the past sulfate reduction 284 00:13:22,540 --> 00:13:20,779 iron manganese nitrate and oxygen 285 00:13:25,150 --> 00:13:22,550 reduction all occur in different subsea 286 00:13:27,880 --> 00:13:25,160 flower environments carbon oxidation 287 00:13:31,030 --> 00:13:27,890 occurs almost everywhere we may see an 288 00:13:33,699 --> 00:13:31,040 exception in a little bit and anywhere 289 00:13:37,060 --> 00:13:33,709 where carbon is being oxidized they're 290 00:13:38,380 --> 00:13:37,070 also intermediate products of metabolic 291 00:13:41,230 --> 00:13:38,390 pathways produced and destroyed 292 00:13:44,829 --> 00:13:41,240 including ammonia acetate lactate 293 00:13:46,120 --> 00:13:44,839 formate hydrogen methane and somewhat 294 00:13:49,120 --> 00:13:46,130 surprisingly ethane and 295 00:13:51,070 --> 00:13:49,130 propane so some of the biological 296 00:13:53,140 --> 00:13:51,080 products that are created in these 297 00:13:55,150 --> 00:13:53,150 environments are actually historically 298 00:13:58,690 --> 00:13:55,160 thought to be a biological meaning the 299 00:14:00,220 --> 00:13:58,700 ethane and propane I'm not going to get 300 00:14:01,840 --> 00:14:00,230 into evidence here for why we think 301 00:14:04,690 --> 00:14:01,850 their biological but I'd be happy to 302 00:14:06,610 --> 00:14:04,700 answer questions on it so this is sort 303 00:14:08,470 --> 00:14:06,620 of a standard model for what happens in 304 00:14:10,840 --> 00:14:08,480 anoxic sediments whether on land or in 305 00:14:14,920 --> 00:14:10,850 the sea the idea is that you start with 306 00:14:17,980 --> 00:14:14,930 organic matter it's fermented by 307 00:14:21,520 --> 00:14:17,990 fermentation the products of 308 00:14:24,970 --> 00:14:21,530 fermentation are then used as a food 309 00:14:29,560 --> 00:14:24,980 source for various reductions manganese 310 00:14:31,870 --> 00:14:29,570 iron and sulfur reduction that those 311 00:14:34,660 --> 00:14:31,880 redox activities constitute respiration 312 00:14:37,990 --> 00:14:34,670 and the products of those reactions are 313 00:14:41,310 --> 00:14:38,000 co2 which is the oxidized product of 314 00:14:43,810 --> 00:14:41,320 what started out as food and manganese 315 00:14:46,150 --> 00:14:43,820 dissolve manganese does reduce manganese 316 00:14:47,890 --> 00:14:46,160 reduced iron and hydrogen sulfide which 317 00:14:52,300 --> 00:14:47,900 are the reduced products of what started 318 00:14:54,480 --> 00:14:52,310 out as oxidants and the evidence that 319 00:14:59,430 --> 00:14:54,490 these processes occur in the sea floor 320 00:15:01,600 --> 00:14:59,440 takes the form initially at least of 321 00:15:07,690 --> 00:15:01,610 profiles of dissolved chemical 322 00:15:10,090 --> 00:15:07,700 concentrations so you see here sulfate 323 00:15:12,000 --> 00:15:10,100 is at a maximum at the top of this 324 00:15:17,640 --> 00:15:12,010 charge and at the bottom of this chart 325 00:15:20,860 --> 00:15:17,650 the top is the sea floor the bottom is 326 00:15:22,690 --> 00:15:20,870 the sediment basalt interface where the 327 00:15:24,760 --> 00:15:22,700 sediment lies on the oceanic crust below 328 00:15:27,640 --> 00:15:24,770 and sulfate is coming into the sediment 329 00:15:30,130 --> 00:15:27,650 from the crust below and from the ocean 330 00:15:31,870 --> 00:15:30,140 above in dissolve form in both cases 331 00:15:34,000 --> 00:15:31,880 seawater is the ultimate source because 332 00:15:36,010 --> 00:15:34,010 seawater flows through the basalt then 333 00:15:38,290 --> 00:15:36,020 the concentrations decreases you move 334 00:15:41,740 --> 00:15:38,300 into the sediment package meaning that 335 00:15:44,920 --> 00:15:41,750 sulfate is being reduced so the 336 00:15:48,100 --> 00:15:44,930 concentration is declining in contrast a 337 00:15:51,250 --> 00:15:48,110 standard product of respiration what we 338 00:15:54,030 --> 00:15:51,260 call dissolved inorganic carbon or total 339 00:15:56,680 --> 00:15:54,040 co2 which is simply the sum of co2 340 00:15:58,600 --> 00:15:56,690 carbonate and bicarbonate shows the 341 00:15:59,750 --> 00:15:58,610 opposite pattern it's at its lowest 342 00:16:02,870 --> 00:15:59,760 value at the top 343 00:16:04,280 --> 00:16:02,880 bottom where it's leaking out and its 344 00:16:07,970 --> 00:16:04,290 highest concentration in the middle 345 00:16:10,970 --> 00:16:07,980 where there is net production just is 346 00:16:12,410 --> 00:16:10,980 there's net loss of the sulfate there so 347 00:16:16,070 --> 00:16:12,420 that provides us with direct evidence 348 00:16:17,720 --> 00:16:16,080 that these processes are occurring we 349 00:16:20,300 --> 00:16:17,730 can actually use those concentration 350 00:16:25,070 --> 00:16:20,310 profiles to calculate net rates of 351 00:16:27,350 --> 00:16:25,080 activity where we use essentially the 352 00:16:32,480 --> 00:16:27,360 chemicals diffusion coefficient the 353 00:16:36,320 --> 00:16:32,490 concentration gradient depth a measure 354 00:16:39,110 --> 00:16:36,330 of porosity it cites the sediment very 355 00:16:40,940 --> 00:16:39,120 rapidly sedimentation rate and we use 356 00:16:44,720 --> 00:16:40,950 some a confirmation factor which is a 357 00:16:49,190 --> 00:16:44,730 proxy for tortuosity tortuosity is just 358 00:16:51,350 --> 00:16:49,200 the deviation from straightness if you 359 00:16:54,340 --> 00:16:51,360 will of the path that the chemical must 360 00:17:02,710 --> 00:16:54,350 follow as it moves through the sediment 361 00:17:05,000 --> 00:17:02,720 no so we've got somebody else live so 362 00:17:09,290 --> 00:17:05,010 formation factor is actually a measure 363 00:17:11,090 --> 00:17:09,300 of the problem they're having I think 364 00:17:14,449 --> 00:17:11,100 Indiana or someone is alive I'm not sure 365 00:17:18,110 --> 00:17:14,459 who I go with ham on the aim is okay 366 00:17:23,120 --> 00:17:18,120 yeah alright so formation factor is is a 367 00:17:24,800 --> 00:17:23,130 measure of the electrical path through 368 00:17:29,390 --> 00:17:24,810 the sediment following the sea water and 369 00:17:30,670 --> 00:17:29,400 the chemicals follow the same path so 370 00:17:33,140 --> 00:17:30,680 I'm not going to go over this in detail 371 00:17:35,240 --> 00:17:33,150 I'm just going to wave a sort of a 372 00:17:37,220 --> 00:17:35,250 little red wand if you will but all of 373 00:17:39,620 --> 00:17:37,230 these products of respiration peak in 374 00:17:42,640 --> 00:17:39,630 the middle of the column these anoxic 375 00:17:44,990 --> 00:17:42,650 sediments so we have methane ammonia 376 00:17:48,800 --> 00:17:45,000 dicl peaking in the middle of the column 377 00:17:51,500 --> 00:17:48,810 and then reactants like sulfate all 378 00:17:54,530 --> 00:17:51,510 decline or even disappear going into the 379 00:17:56,060 --> 00:17:54,540 column that's telling us multiple 380 00:17:58,850 --> 00:17:56,070 processes are occurring deep in the 381 00:18:01,100 --> 00:17:58,860 sediment everywhere so we take the 382 00:18:02,900 --> 00:18:01,110 results of those flux calculations we 383 00:18:04,580 --> 00:18:02,910 can calculate how much electron 384 00:18:06,890 --> 00:18:04,590 acceptance is done by these different 385 00:18:08,990 --> 00:18:06,900 processes in different regions so I'm 386 00:18:11,900 --> 00:18:09,000 just going to highlight the bold-faced 387 00:18:13,190 --> 00:18:11,910 things here the marginal sites like 388 00:18:15,440 --> 00:18:13,200 along the prune margin where 389 00:18:19,399 --> 00:18:15,450 the cell counts resemble the traditional 390 00:18:22,909 --> 00:18:19,409 ODP counts the dominant process is 391 00:18:27,769 --> 00:18:22,919 sulfate reduction then as we move into 392 00:18:29,299 --> 00:18:27,779 the progressively lower activity regions 393 00:18:30,799 --> 00:18:29,309 of the ocean move out into the epitome 394 00:18:34,039 --> 00:18:30,809 Pacific sulfate reduction still 395 00:18:35,840 --> 00:18:34,049 dominates at the most active sites but 396 00:18:38,389 --> 00:18:35,850 then metal reduction becomes 397 00:18:41,360 --> 00:18:38,399 increasingly important so at the lowest 398 00:18:43,519 --> 00:18:41,370 activity site we visited in 2002 the 399 00:18:48,220 --> 00:18:43,529 dominant process the Domino electron 400 00:18:53,930 --> 00:18:50,720 now if we go to the sites we visited in 401 00:18:56,000 --> 00:18:53,940 December and January of this winter we 402 00:18:57,710 --> 00:18:56,010 see so that the sediments in fact aren't 403 00:19:00,560 --> 00:18:57,720 anoxic they're unlike any sediments 404 00:19:03,680 --> 00:19:00,570 people have ever core deeply into and 405 00:19:05,570 --> 00:19:03,690 looked for life what we see there this 406 00:19:10,250 --> 00:19:05,580 is our little site that the Antarctic 407 00:19:11,810 --> 00:19:10,260 convergence down here their oxygen 408 00:19:13,600 --> 00:19:11,820 disappears in the first metre of the 409 00:19:15,560 --> 00:19:13,610 sediment columns that's a typical 410 00:19:18,680 --> 00:19:15,570 sediment in the sense of what people 411 00:19:20,210 --> 00:19:18,690 expect but all of the other sites the 412 00:19:23,690 --> 00:19:20,220 sites that were in that red box where 413 00:19:26,090 --> 00:19:23,700 the cell counts are so low are over here 414 00:19:28,240 --> 00:19:26,100 so there's 150 micro molar or more 415 00:19:30,350 --> 00:19:28,250 oxygen throughout the settlement column 416 00:19:32,539 --> 00:19:30,360 that's following along this arrow here 417 00:19:34,960 --> 00:19:32,549 so that's essentially again in the 418 00:19:37,820 --> 00:19:34,970 region of turquoise dark blue and black 419 00:19:41,360 --> 00:19:37,830 photos chlorophyll content in the 420 00:19:44,330 --> 00:19:41,370 overlying ocean and nitrate is always 421 00:19:47,200 --> 00:19:44,340 above or at deep water concentrations 422 00:19:50,029 --> 00:19:47,210 it's a little bit of nitrate produced by 423 00:19:51,320 --> 00:19:50,039 oxidation of organic nitrogen in the 424 00:19:53,360 --> 00:19:51,330 shallow sediments and that's what makes 425 00:19:55,009 --> 00:19:53,370 a little high and there's no nitrate 426 00:19:59,539 --> 00:19:55,019 reduction below so what we're seeing 427 00:20:11,360 --> 00:19:59,549 here and sulfate doesn't change at all 428 00:20:16,580 --> 00:20:14,049 in terms of carbon equivalents per year 429 00:20:19,580 --> 00:20:16,590 is in the range here of 10 to the minus 430 00:20:23,210 --> 00:20:19,590 16 to 10 to the minus 18 moles per cell 431 00:20:24,860 --> 00:20:23,220 per year in coastal sediments you see 432 00:20:27,650 --> 00:20:24,870 numbers more the ballpark of 10 to the 433 00:20:28,940 --> 00:20:27,660 minus 15 and in pure culture is it's 434 00:20:34,220 --> 00:20:28,950 typically in the range of ten to the 435 00:20:38,000 --> 00:20:34,230 minus 13 to 10 to the minus 11 so this 436 00:20:40,670 --> 00:20:38,010 is the sort of odd claim because 437 00:20:42,860 --> 00:20:40,680 essentially we're claiming that sub 438 00:20:45,230 --> 00:20:42,870 seafloor organisms on average are 439 00:20:46,910 --> 00:20:45,240 aspiring it much much lower rates than 440 00:20:49,640 --> 00:20:46,920 anyone's observed in the service world 441 00:20:53,410 --> 00:20:49,650 now you have a couple of possible ways 442 00:20:55,760 --> 00:20:53,420 of explaining this one the claim is true 443 00:21:00,320 --> 00:20:55,770 these things are aspiring very very 444 00:21:03,500 --> 00:21:00,330 slowly to it's conceivable that we've 445 00:21:07,430 --> 00:21:03,510 missed some huge huge source of 446 00:21:16,580 --> 00:21:07,440 respiration somehow orders of magnitude 447 00:21:18,230 --> 00:21:16,590 and three it's possible that only a 448 00:21:20,780 --> 00:21:18,240 fraction of the cells counted are 449 00:21:22,460 --> 00:21:20,790 actually alive and respiring so if we 450 00:21:24,500 --> 00:21:22,470 were to take for example the shippers 451 00:21:27,440 --> 00:21:24,510 estimate that ten percent of the cells 452 00:21:28,970 --> 00:21:27,450 are alive but perhaps no more then all 453 00:21:31,070 --> 00:21:28,980 of these could be brought down an order 454 00:21:33,290 --> 00:21:31,080 brought up in order of magnitude and 455 00:21:36,440 --> 00:21:33,300 maybe 10 to the minus 17 to 10 to the 456 00:21:45,159 --> 00:21:36,450 minus 15 the low end they'd start edging 457 00:21:49,370 --> 00:21:47,810 so what we decided to do was to see 458 00:21:52,870 --> 00:21:49,380 whether we were missing some obvious 459 00:21:56,149 --> 00:21:52,880 source of or even in obvious source of 460 00:21:57,770 --> 00:21:56,159 respiration instead of assuming as we 461 00:22:00,200 --> 00:21:57,780 did that sulfate reduction was the 462 00:22:03,380 --> 00:22:00,210 dominant process as we did in our 2002 463 00:22:05,480 --> 00:22:03,390 paper we said let's look at the amount 464 00:22:07,700 --> 00:22:05,490 of DIC produced the amount of co2 465 00:22:11,390 --> 00:22:07,710 produced by respiration of organic 466 00:22:13,640 --> 00:22:11,400 matter so there are two two things that 467 00:22:15,320 --> 00:22:13,650 we have to consider here the first we 468 00:22:18,279 --> 00:22:15,330 have to consider the flux of dissolved 469 00:22:21,169 --> 00:22:18,289 inorganic carbon out of the sediment 470 00:22:23,570 --> 00:22:21,179 second we have to consider the amount of 471 00:22:26,720 --> 00:22:23,580 carbon that precipitated out as a 472 00:22:29,060 --> 00:22:26,730 carbonate mineral within the sediment so 473 00:22:32,419 --> 00:22:29,070 that's enough in a sense a hit term we 474 00:22:33,649 --> 00:22:32,429 can calculate that second flux by 475 00:22:37,340 --> 00:22:33,659 looking at the calcium and magnesium 476 00:22:41,630 --> 00:22:37,350 fluxes into the sediment so it's 477 00:22:43,490 --> 00:22:41,640 quantifiable and when we do that we can 478 00:22:47,360 --> 00:22:43,500 calculate carbon oxidation rates at 479 00:22:49,520 --> 00:22:47,370 different depths take the cell counts 480 00:22:53,080 --> 00:22:49,530 and calculate the carbon oxidation rate 481 00:22:55,279 --> 00:22:53,090 per cell and you see that using this 482 00:22:58,340 --> 00:22:55,289 carbon based approach we're still 483 00:23:00,620 --> 00:22:58,350 getting average values for carbon 484 00:23:04,909 --> 00:23:00,630 oxidation of around 10 to the minus 17 485 00:23:06,529 --> 00:23:04,919 moles per cell per year so this 486 00:23:08,539 --> 00:23:06,539 essentially means that we aren't missing 487 00:23:10,549 --> 00:23:08,549 a very big source of respiration 488 00:23:12,620 --> 00:23:10,559 somewhere in the system and that either 489 00:23:14,390 --> 00:23:12,630 most of the cells are not active or they 490 00:23:19,730 --> 00:23:14,400 really are breathing it phenomenally 491 00:23:21,610 --> 00:23:19,740 slow rates but again if ten percent of 492 00:23:24,440 --> 00:23:21,620 the cells are active as shippers says 493 00:23:26,480 --> 00:23:24,450 then there's still less active than 494 00:23:29,590 --> 00:23:26,490 anything known in the surface world so 495 00:23:32,620 --> 00:23:29,600 just for comparison here's the total 496 00:23:35,840 --> 00:23:32,630 flux assume by looking at the oxidation 497 00:23:36,950 --> 00:23:35,850 the sort of the reduced products if you 498 00:23:39,409 --> 00:23:36,960 will which is where we've done these 499 00:23:41,390 --> 00:23:39,419 calculations in the past and this is the 500 00:23:43,460 --> 00:23:41,400 flux from the co2 mass balance which is 501 00:23:44,630 --> 00:23:43,470 Lee at the oxidized products you see 502 00:23:51,560 --> 00:23:44,640 that the two numbers are nearly 503 00:23:58,310 --> 00:23:56,540 let's go back there okay if I transfer 504 00:24:02,720 --> 00:23:58,320 this is a screen capture a few minutes 505 00:24:04,040 --> 00:24:02,730 ago and lost my fields the in here this 506 00:24:08,420 --> 00:24:04,050 is the amount of energy that price and 507 00:24:10,280 --> 00:24:08,430 sours infer is required just to keep the 508 00:24:13,840 --> 00:24:10,290 organisms ahead of rasim ization of 509 00:24:18,260 --> 00:24:17,150 isomer is reverting over time the 510 00:24:22,100 --> 00:24:18,270 traditional estimates of maintenance 511 00:24:23,540 --> 00:24:22,110 energy up around here so coastal shallow 512 00:24:26,030 --> 00:24:23,550 sediments organisms were already 513 00:24:29,750 --> 00:24:26,040 operating near the inferred maintenance 514 00:24:32,330 --> 00:24:29,760 energy necessary for life what we're 515 00:24:33,620 --> 00:24:32,340 seeing here is that these microbial 516 00:24:35,540 --> 00:24:33,630 communities are actually being 517 00:24:38,300 --> 00:24:35,550 maintained at far lower rates of 518 00:24:40,010 --> 00:24:38,310 respiration than theoretical estimates 519 00:24:44,390 --> 00:24:40,020 of maintenance energy have allowed in 520 00:24:46,430 --> 00:24:44,400 the past so if nothing else physiology 521 00:24:51,100 --> 00:24:46,440 of microbial maintenance isn't yet well 522 00:24:53,300 --> 00:24:51,110 understood I'm going to focus very 523 00:24:55,550 --> 00:24:53,310 briefly here on something that one of 524 00:24:59,240 --> 00:24:55,560 our graduate students did part of her 525 00:25:01,280 --> 00:24:59,250 thesis work on essentially there's 526 00:25:03,710 --> 00:25:01,290 thermodynamic cooperation going on in 527 00:25:05,720 --> 00:25:03,720 these systems I'm going to breeze 528 00:25:09,830 --> 00:25:05,730 through this fairly quickly but what you 529 00:25:15,410 --> 00:25:09,840 see here this table essentially 530 00:25:18,560 --> 00:25:15,420 calculates how much carbon is oxidized 531 00:25:21,580 --> 00:25:18,570 by a given process so sulfate reduction 532 00:25:25,400 --> 00:25:21,590 iron reduction manganese reduction and 533 00:25:26,900 --> 00:25:25,410 how much carbon 'it is precipitated as a 534 00:25:31,940 --> 00:25:26,910 result of the changes in the alkalinity 535 00:25:33,710 --> 00:25:31,950 due to that process and then we look at 536 00:25:36,530 --> 00:25:33,720 essentially not just then the mass 537 00:25:39,320 --> 00:25:36,540 balance of say the reductions and the 538 00:25:41,780 --> 00:25:39,330 carbon oxidation but also effectively 539 00:25:45,440 --> 00:25:41,790 the mass balance of the carbonate 540 00:25:47,930 --> 00:25:45,450 precipitation and the reductions when we 541 00:25:51,590 --> 00:25:47,940 do that we find that if you were to take 542 00:25:53,660 --> 00:25:51,600 this DIC flux and this carbon of flux 543 00:25:56,150 --> 00:25:53,670 and sum them you'd be nearly equal to 544 00:25:58,340 --> 00:25:56,160 the sulfate reduction rate so those two 545 00:26:00,080 --> 00:25:58,350 numbers are nearly balanced so from a 546 00:26:03,500 --> 00:26:00,090 DIC purse or from a carbon production 547 00:26:05,360 --> 00:26:03,510 perspective given the uncertainties of 548 00:26:07,070 --> 00:26:05,370 our approach you don't need to 549 00:26:10,160 --> 00:26:07,080 call on anything but sulfate reduction 550 00:26:12,710 --> 00:26:10,170 for this system but it turns out when 551 00:26:14,570 --> 00:26:12,720 you reduce sulfate you actually dissolve 552 00:26:18,470 --> 00:26:14,580 a little carbon it you don't produce it 553 00:26:19,730 --> 00:26:18,480 and here it's being produced so what 554 00:26:21,380 --> 00:26:19,740 we're seeing is that the carbonate 555 00:26:24,200 --> 00:26:21,390 precipitation is too high to be 556 00:26:27,710 --> 00:26:24,210 explained by sulfate reduction so the 557 00:26:30,740 --> 00:26:27,720 simplest way to get lots of carbonate 558 00:26:32,390 --> 00:26:30,750 precipitation is to add a little iron 559 00:26:34,580 --> 00:26:32,400 reduction along with the sulfate 560 00:26:36,290 --> 00:26:34,590 reduction because it turns out the iron 561 00:26:39,020 --> 00:26:36,300 reduction you end up precipitating a lot 562 00:26:40,340 --> 00:26:39,030 of carbonate so what this is telling us 563 00:26:43,310 --> 00:26:40,350 what this balance is telling us 564 00:26:44,990 --> 00:26:43,320 effectively is that iron reduction in 565 00:26:47,510 --> 00:26:45,000 sulfate reduction of co-occurring in 566 00:26:49,640 --> 00:26:47,520 these sediments this is a little 567 00:26:58,950 --> 00:26:49,650 unexpected for some people because 568 00:27:04,680 --> 00:27:01,460 your depth what we're seeing here is 569 00:27:06,870 --> 00:27:04,690 that throughout a sediment column that 570 00:27:09,120 --> 00:27:06,880 was deposited over about 15 million 571 00:27:13,740 --> 00:27:09,130 years iron and sulfate reduction are 572 00:27:16,440 --> 00:27:13,750 occurring together so the iron hasn't 573 00:27:18,899 --> 00:27:16,450 out competed sulfate instead both of 574 00:27:25,200 --> 00:27:18,909 those two are co-occurring so take a 575 00:27:29,370 --> 00:27:25,210 closer look at that essentially what we 576 00:27:31,110 --> 00:27:29,380 believe is that is that in a sense these 577 00:27:33,720 --> 00:27:31,120 communities constitute an underground 578 00:27:36,269 --> 00:27:33,730 economy where there's an invisible hand 579 00:27:39,419 --> 00:27:36,279 of thermodynamics keeping the system in 580 00:27:42,269 --> 00:27:39,429 play you look here at these figure at 581 00:27:45,180 --> 00:27:42,279 this figure these are the Institute free 582 00:27:50,399 --> 00:27:45,190 energies of acetate oxidation using 583 00:27:51,450 --> 00:27:50,409 hematite reduction with a magenta this 584 00:27:53,970 --> 00:27:51,460 is basically just acetate 585 00:27:56,610 --> 00:27:53,980 disproportionate and sulfate reduction 586 00:27:58,490 --> 00:27:56,620 and you see that all of these free 587 00:28:02,789 --> 00:27:58,500 energies are in the range of around 588 00:28:06,899 --> 00:28:02,799 minus 52 minus 20 kilojoules per mole of 589 00:28:08,460 --> 00:28:06,909 acetate the minimum free energy of this 590 00:28:13,110 --> 00:28:08,470 reaction is typically assumed to be 591 00:28:14,970 --> 00:28:13,120 somewhere in this in this region so 592 00:28:16,680 --> 00:28:14,980 these are very low free energies needle 593 00:28:18,480 --> 00:28:16,690 you see they're also pretty constant 594 00:28:19,889 --> 00:28:18,490 throughout the sediment column the ones 595 00:28:22,200 --> 00:28:19,899 where all of the products and reactants 596 00:28:23,639 --> 00:28:22,210 are dissolved with Anna Genesis and 597 00:28:26,430 --> 00:28:23,649 sulfate reduction there they're nearly 598 00:28:29,519 --> 00:28:26,440 constant where we're inferring a mineral 599 00:28:31,080 --> 00:28:29,529 it's more variable this could mean that 600 00:28:33,180 --> 00:28:31,090 the free energy of that reaction truly 601 00:28:36,120 --> 00:28:33,190 varies from depth to depth or it could 602 00:28:37,440 --> 00:28:36,130 mean that different iron containing 603 00:28:39,000 --> 00:28:37,450 minerals are being used at different 604 00:28:42,419 --> 00:28:39,010 depths in the free energies more nearly 605 00:28:45,090 --> 00:28:42,429 constant the standard free energies of 606 00:28:46,470 --> 00:28:45,100 these reactions vary considerably the 607 00:28:48,930 --> 00:28:46,480 standard free energy of the iron 608 00:28:51,060 --> 00:28:48,940 reduction it's somewhere around minus 609 00:28:53,639 --> 00:28:51,070 fourteen hundred kilojoules per mole of 610 00:28:56,100 --> 00:28:53,649 acetate the standard free energy of the 611 00:28:58,230 --> 00:28:56,110 sulfur reduction is roughly an order of 612 00:29:00,240 --> 00:28:58,240 magnitude less than that but still well 613 00:29:02,070 --> 00:29:00,250 off the charts here so what we're seeing 614 00:29:04,230 --> 00:29:02,080 is that all of these processes are 615 00:29:06,840 --> 00:29:04,240 operating fairly close to a biological 616 00:29:10,419 --> 00:29:06,850 minimum and they're relatively constant 617 00:29:15,609 --> 00:29:12,430 so that implies that there's some sort 618 00:29:19,659 --> 00:29:15,619 of thermodynamic homeostatic you will 619 00:29:21,789 --> 00:29:19,669 with the thermodynamics sustaining this 620 00:29:24,310 --> 00:29:21,799 process I'm going to I don't have a 621 00:29:25,960 --> 00:29:24,320 slide to explain this so I'll just 622 00:29:31,330 --> 00:29:25,970 describe some examples of how this might 623 00:29:33,460 --> 00:29:31,340 work as sulfate reduction proceeds 624 00:29:35,320 --> 00:29:33,470 you're going to build up dissolved 625 00:29:40,739 --> 00:29:35,330 sulphide and you're going to build up 626 00:29:42,850 --> 00:29:40,749 dissolved co2 the products of 627 00:29:45,190 --> 00:29:42,860 thermodynamic reactions is you probably 628 00:29:47,169 --> 00:29:45,200 all know poison the reactions so if you 629 00:29:48,940 --> 00:29:47,179 allow product concentrations to build up 630 00:29:51,249 --> 00:29:48,950 the free energies of the reactions go 631 00:29:53,320 --> 00:29:51,259 down so if you let your dissolved iron 632 00:29:56,409 --> 00:29:53,330 concentrations go up the free energy of 633 00:29:58,600 --> 00:29:56,419 iron reduction goes down if you let your 634 00:30:01,509 --> 00:29:58,610 dissolve sulphur concentrations go up 635 00:30:04,960 --> 00:30:01,519 the free energy of sulphur reduction 636 00:30:07,840 --> 00:30:04,970 goes down very conveniently however if 637 00:30:09,450 --> 00:30:07,850 you have reduced iron and reduce sulfur 638 00:30:12,369 --> 00:30:09,460 produced in the same system that 639 00:30:16,359 --> 00:30:12,379 precipitate out together is as iron 640 00:30:19,149 --> 00:30:16,369 sulphide so the coexistence of these 641 00:30:22,720 --> 00:30:19,159 reactions allows their products to scrub 642 00:30:25,930 --> 00:30:22,730 each other out so effectively what we're 643 00:30:28,350 --> 00:30:25,940 suggesting is that in a sense these 644 00:30:30,700 --> 00:30:28,360 organisms are cleaning up the 645 00:30:33,720 --> 00:30:30,710 respiration products of each other and 646 00:30:35,950 --> 00:30:33,730 allowing the reactions to proceed 647 00:30:38,169 --> 00:30:35,960 methanogenesis similarly when methane is 648 00:30:40,090 --> 00:30:38,179 produced that methane can then be used 649 00:30:42,220 --> 00:30:40,100 as a food source by the sulfate reducers 650 00:30:44,409 --> 00:30:42,230 in the iron reduced so the implication 651 00:30:45,999 --> 00:30:44,419 is that on the timescales of millions of 652 00:30:49,060 --> 00:30:46,009 years over which ecosystems are 653 00:30:52,299 --> 00:30:49,070 operating these systems reach a more or 654 00:30:53,289 --> 00:30:52,309 less stable point where these processes 655 00:30:55,659 --> 00:30:53,299 that are traditionally believed to 656 00:31:00,310 --> 00:30:55,669 compete can in fact coexist because 657 00:31:03,399 --> 00:31:00,320 they're cooperating at some level so I'm 658 00:31:06,039 --> 00:31:03,409 going to briefly speak then about some 659 00:31:12,520 --> 00:31:06,049 of these processes in terms of their 660 00:31:21,150 --> 00:31:16,650 I suspect that everyone here today 661 00:31:24,820 --> 00:31:21,160 recognizes that methane is a significant 662 00:31:27,040 --> 00:31:24,830 greenhouse gas it has much lower 663 00:31:30,580 --> 00:31:27,050 concentrations than co2 which we see in 664 00:31:35,290 --> 00:31:30,590 the news a lot but its effect on global 665 00:31:38,440 --> 00:31:35,300 warming per unit of atmosphere 666 00:31:40,480 --> 00:31:38,450 constituent is much greater so one 667 00:31:42,670 --> 00:31:40,490 consequence of this subsurface world is 668 00:31:47,050 --> 00:31:42,680 that the methane produced by these 669 00:31:49,030 --> 00:31:47,060 microbes can and probably on long time 670 00:31:51,460 --> 00:31:49,040 scales does significantly affect or its 671 00:31:54,010 --> 00:31:51,470 climate for example the really big 672 00:31:56,140 --> 00:31:54,020 global warming event 255 million years 673 00:31:58,630 --> 00:31:56,150 ago is generally inferred to have been 674 00:32:00,910 --> 00:31:58,640 the result of subsea floor methane being 675 00:32:04,300 --> 00:32:00,920 discouraged that methane is principally 676 00:32:07,660 --> 00:32:04,310 created by methanogens microorganisms 677 00:32:09,370 --> 00:32:07,670 beneath the sea floor for those of you 678 00:32:12,190 --> 00:32:09,380 who are less climate focused and more 679 00:32:13,750 --> 00:32:12,200 resource focused these sub seafloor 680 00:32:15,790 --> 00:32:13,760 methane deposits are actually the 681 00:32:18,190 --> 00:32:15,800 largest untapped fossil fuel reservoir 682 00:32:21,820 --> 00:32:18,200 on earth so here's an example where 683 00:32:24,730 --> 00:32:21,830 these relatively slow activities by 684 00:32:28,150 --> 00:32:24,740 these sub seafloor microorganisms have 685 00:32:30,700 --> 00:32:28,160 global implications I'm going to point 686 00:32:34,390 --> 00:32:30,710 to another example that to the best of 687 00:32:36,400 --> 00:32:34,400 my knowledge is not publicly discussed 688 00:32:40,860 --> 00:32:36,410 except by me and hasn't actually been 689 00:32:43,990 --> 00:32:40,870 published and that is that ultimately 690 00:32:48,760 --> 00:32:44,000 subsea flower sulfate reduction affects 691 00:32:52,560 --> 00:32:48,770 atmospheric co2 or to put it a little 692 00:32:55,990 --> 00:32:52,570 differently the process of oxidation of 693 00:32:58,720 --> 00:32:56,000 sulfur reduced sulfur and reduction of 694 00:33:01,960 --> 00:32:58,730 oxidized sulfur affects atmospheric co2 695 00:33:03,700 --> 00:33:01,970 so if we increase our current 696 00:33:08,680 --> 00:33:03,710 concentration of dissolved sulfate in 697 00:33:12,130 --> 00:33:08,690 the ocean is about 28 millimolar if we 698 00:33:16,240 --> 00:33:12,140 increase the concentration by 1 699 00:33:18,610 --> 00:33:16,250 millimolar the effect on ocean 700 00:33:22,180 --> 00:33:18,620 alkalinity will drive up atmospheric co2 701 00:33:24,710 --> 00:33:22,190 by a factor of 3 so if we decrease the 702 00:33:26,960 --> 00:33:24,720 concentration by 1 millimolar 703 00:33:31,370 --> 00:33:26,970 it'll pull out mysterious co2 down to 704 00:33:33,380 --> 00:33:31,380 nearly zero this calculation is 705 00:33:35,090 --> 00:33:33,390 effectively in terms of subsea floor in 706 00:33:37,460 --> 00:33:35,100 terms of sulfate reduction this 707 00:33:39,770 --> 00:33:37,470 calculation is relative to say carbon 708 00:33:42,320 --> 00:33:39,780 oxidation by free oxygen instead of 709 00:33:49,730 --> 00:33:42,330 bisulfate effectively oxygen has no 710 00:33:52,390 --> 00:33:49,740 effect on reduction and this would be 711 00:33:54,260 --> 00:33:52,400 relative to that you get a cleaner 712 00:33:57,049 --> 00:33:54,270 relationship if you're just to look at 713 00:33:59,390 --> 00:33:57,059 pyrite oxidation if you oxidize more 714 00:34:01,100 --> 00:33:59,400 pyrite you will drive the absolute 715 00:34:03,380 --> 00:34:01,110 concentration up by this without having 716 00:34:07,010 --> 00:34:03,390 to worry about any respiration effect or 717 00:34:09,290 --> 00:34:07,020 the co2 so the basic point is that that 718 00:34:10,669 --> 00:34:09,300 this is a very very strong lever for 719 00:34:15,139 --> 00:34:10,679 changing the composition of the 720 00:34:19,790 --> 00:34:15,149 atmosphere and ocean put it in sort of a 721 00:34:21,770 --> 00:34:19,800 text form the removal of sulfate from 722 00:34:24,440 --> 00:34:21,780 the ocean by precipitation of iron 723 00:34:27,349 --> 00:34:24,450 sulfide is equivalent to removal of a 724 00:34:29,810 --> 00:34:27,359 strong acid similarly the addition of 725 00:34:32,450 --> 00:34:29,820 sulfate to the ocean by weathering of 726 00:34:35,450 --> 00:34:32,460 iron sulfide is equivalent to creation 727 00:34:37,550 --> 00:34:35,460 and addition of a strong acid and this 728 00:34:39,470 --> 00:34:37,560 may actually serve to modulators climate 729 00:34:42,020 --> 00:34:39,480 on long time scales you know for example 730 00:34:43,879 --> 00:34:42,030 when we have warm climates we have low 731 00:34:46,369 --> 00:34:43,889 dissolved oxygen in the ocean because 732 00:34:50,060 --> 00:34:46,379 warm water holds less gas than cold 733 00:34:51,950 --> 00:34:50,070 water consequently less organic carbon 734 00:34:54,349 --> 00:34:51,960 goes to oxygen reduction more goes to 735 00:34:56,260 --> 00:34:54,359 sulfate reduction and you can increase 736 00:34:59,030 --> 00:34:56,270 the iron sulphide burial in the deep sea 737 00:35:01,720 --> 00:34:59,040 which in turn can pull down atmospheric 738 00:35:04,220 --> 00:35:01,730 co2 and cool the atmosphere and ocean 739 00:35:06,020 --> 00:35:04,230 now this is a process that's not going 740 00:35:07,520 --> 00:35:06,030 to save us on the time scale of fossil 741 00:35:09,349 --> 00:35:07,530 fuel burning because the rates are 742 00:35:11,089 --> 00:35:09,359 relatively slow this is a sort of 743 00:35:12,560 --> 00:35:11,099 process that plays out on time scales of 744 00:35:17,720 --> 00:35:12,570 hundreds of thousands to millions of 745 00:35:19,130 --> 00:35:17,730 years now I'm going to briefly touch on 746 00:35:20,960 --> 00:35:19,140 something that's a particular interest 747 00:35:23,450 --> 00:35:20,970 to some in the NAI community 748 00:35:25,599 --> 00:35:23,460 particularly people the Indiana team who 749 00:35:29,060 --> 00:35:25,609 have done a very nice job working with 750 00:35:31,460 --> 00:35:29,070 deep gold mines we're going to look at 751 00:35:33,230 --> 00:35:31,470 something that isn't does not appear to 752 00:35:34,430 --> 00:35:33,240 be analogous but in fact maybe in some 753 00:35:36,550 --> 00:35:34,440 ways analogous to what they're looking 754 00:35:39,830 --> 00:35:36,560 at there 755 00:35:42,160 --> 00:35:39,840 the principal sources of food or 756 00:35:45,040 --> 00:35:42,170 electron donors for subsea floor life 757 00:35:48,980 --> 00:35:45,050 are the burial of photosynthesize 758 00:35:52,610 --> 00:35:48,990 organic matter the radioactive splitting 759 00:35:56,480 --> 00:35:52,620 of water potentially alteration that 760 00:36:00,400 --> 00:35:56,490 would be oxidation or reduction of 761 00:36:03,050 --> 00:36:00,410 minerals and the thermal creation of 762 00:36:05,420 --> 00:36:03,060 organic matter or other reduced 763 00:36:07,280 --> 00:36:05,430 compounds so there's sorts of sediments 764 00:36:08,960 --> 00:36:07,290 that my team principally focuses on we 765 00:36:11,030 --> 00:36:08,970 can ignore both mineral alteration and 766 00:36:13,520 --> 00:36:11,040 thermogenesis these are very cold 767 00:36:16,430 --> 00:36:13,530 sediments so thermogenesis is not an 768 00:36:17,960 --> 00:36:16,440 issue and in the lowest activity 769 00:36:19,310 --> 00:36:17,970 sediments that we look at everything is 770 00:36:22,820 --> 00:36:19,320 oxidized so there aren't any real 771 00:36:25,670 --> 00:36:22,830 minerals around to be oxidized as 772 00:36:27,710 --> 00:36:25,680 they've all been oxidized in advance so 773 00:36:30,350 --> 00:36:27,720 instead I'm going to focus on burial of 774 00:36:32,060 --> 00:36:30,360 photosynthesize organic matter here's a 775 00:36:34,930 --> 00:36:32,070 pretty picture from Steve passion 776 00:36:37,190 --> 00:36:34,940 colleagues showing microbes growing on a 777 00:36:39,620 --> 00:36:37,200 carboniferous black shale that he's 778 00:36:41,570 --> 00:36:39,630 exposed in a thin section just showing 779 00:36:42,740 --> 00:36:41,580 that if you can get organic matter to 780 00:36:45,140 --> 00:36:42,750 them they'll use it even if it's 781 00:36:46,430 --> 00:36:45,150 hundreds and millions years old this is 782 00:36:48,860 --> 00:36:46,440 a little schematic that just shows the 783 00:36:51,670 --> 00:36:48,870 process of radiolysis of water where you 784 00:36:55,790 --> 00:36:51,680 have decay of uranium thorium potassium 785 00:36:59,210 --> 00:36:55,800 creating alpha beta gamma radiation and 786 00:37:01,850 --> 00:36:59,220 that radiation some subset of it strikes 787 00:37:05,180 --> 00:37:01,860 mineral grains and essentially just goes 788 00:37:08,270 --> 00:37:05,190 into leaving fission tracks if you will 789 00:37:10,610 --> 00:37:08,280 but any of it that gets out of the 790 00:37:12,910 --> 00:37:10,620 mineral out of the rock and into the 791 00:37:15,440 --> 00:37:12,920 surrounding water will split the water 792 00:37:18,260 --> 00:37:15,450 there's about 30 of these radiolytic 793 00:37:23,390 --> 00:37:18,270 reactions but the stable products of 794 00:37:28,870 --> 00:37:23,400 them are water again hydrogen from 795 00:37:33,320 --> 00:37:31,070 when we do mass balance calculations 796 00:37:36,620 --> 00:37:33,330 based on burial rates of organic matter 797 00:37:39,380 --> 00:37:36,630 and the reduction rate such I showed you 798 00:37:42,860 --> 00:37:39,390 earlier the relatively high activity 799 00:37:44,780 --> 00:37:42,870 sites that we went to in 2002 these Peru 800 00:37:49,100 --> 00:37:44,790 margin sites and these open Pacific 801 00:37:49,799 --> 00:37:49,110 sites essentially burial of organic 802 00:37:53,249 --> 00:37:49,809 matter 803 00:37:55,620 --> 00:37:53,259 is providing enough food to sustain the 804 00:37:57,689 --> 00:37:55,630 net rates of sulfate metal and nitrate 805 00:37:59,429 --> 00:37:57,699 reduction that we see at those sites you 806 00:38:01,829 --> 00:37:59,439 see that these numbers are generally in 807 00:38:03,630 --> 00:38:01,839 the same order of magnitude or the 808 00:38:05,309 --> 00:38:03,640 second number is higher than the first 809 00:38:06,959 --> 00:38:05,319 so that's telling us there's enough 810 00:38:10,769 --> 00:38:06,969 organic matter around to sustain those 811 00:38:12,719 --> 00:38:10,779 processes so at those traditional anoxic 812 00:38:18,779 --> 00:38:12,729 settlements the principal source of food 813 00:38:20,729 --> 00:38:18,789 is basically buried organic matter so 814 00:38:22,499 --> 00:38:20,739 let's take a little closer look at how 815 00:38:25,170 --> 00:38:22,509 much energy might come from the 816 00:38:26,939 --> 00:38:25,180 alternative process the radiolysis so 817 00:38:29,789 --> 00:38:26,949 these are the same sites ordered from 818 00:38:32,479 --> 00:38:29,799 high to low energy what we've done here 819 00:38:35,269 --> 00:38:32,489 is we've calculated how much radioactive 820 00:38:37,829 --> 00:38:35,279 radiologic hydrogen would be created 821 00:38:39,630 --> 00:38:37,839 given the uranium thorium of potassium 822 00:38:42,120 --> 00:38:39,640 content of the sediment in its porosity 823 00:38:43,679 --> 00:38:42,130 we compare that to the carbon fueled 824 00:38:47,219 --> 00:38:43,689 respiration that you saw in the previous 825 00:38:49,769 --> 00:38:47,229 slide and get a ratio of the two what 826 00:38:53,640 --> 00:38:49,779 you find is that at the ocean margin 827 00:38:55,559 --> 00:38:53,650 sites like 1230 less than 1 percent of 828 00:38:58,829 --> 00:38:55,569 the energy or the food that fuels that 829 00:39:02,160 --> 00:38:58,839 system comes from radioactive splitting 830 00:39:05,039 --> 00:39:02,170 of water as we move offshore into lower 831 00:39:07,079 --> 00:39:05,049 and lower activity sediments to get to 832 00:39:11,219 --> 00:39:07,089 the pru basin where manganese reduction 833 00:39:15,599 --> 00:39:11,229 is the dominant process radioactive 834 00:39:17,699 --> 00:39:15,609 splitting of water at least based on our 835 00:39:19,410 --> 00:39:17,709 calculations appears to provide a little 836 00:39:21,029 --> 00:39:19,420 over ten percent of the amount of energy 837 00:39:24,959 --> 00:39:21,039 that the Buried organic matter is 838 00:39:27,299 --> 00:39:24,969 providing to the system so what is 839 00:39:29,279 --> 00:39:27,309 another way of looking at this that's a 840 00:39:31,529 --> 00:39:29,289 site where we had around a hundred 841 00:39:34,559 --> 00:39:31,539 thousand cells per cubic centimeter of 842 00:39:37,109 --> 00:39:34,569 sediment so if we were to go to a site 843 00:39:38,669 --> 00:39:37,119 where we simply had radioactive 844 00:39:39,900 --> 00:39:38,679 splitting of water as our only source of 845 00:39:42,259 --> 00:39:39,910 energy and we had the same amount of 846 00:39:45,449 --> 00:39:42,269 radiolysis we'd be able to support 847 00:39:50,480 --> 00:39:45,459 around ten thousand cells per cubic 848 00:40:02,420 --> 00:39:56,240 and when we go to the gyre this is this 849 00:40:06,980 --> 00:40:02,430 is sort of right here you see that 850 00:40:09,530 --> 00:40:06,990 oxygen didn't disappear our estimates of 851 00:40:11,120 --> 00:40:09,540 total act of net activity are three 852 00:40:14,900 --> 00:40:11,130 orders of magnitude less than in any 853 00:40:17,600 --> 00:40:14,910 sites where people have looked before so 854 00:40:19,400 --> 00:40:17,610 it looks like this is a region where if 855 00:40:21,010 --> 00:40:19,410 the sediments are as radioactive is 856 00:40:23,300 --> 00:40:21,020 those we've seen at the other sites 857 00:40:24,890 --> 00:40:23,310 radiolysis may in fact be the principal 858 00:40:27,500 --> 00:40:24,900 source of food for the subsurface 859 00:40:32,950 --> 00:40:27,510 ecosystem now it's important to bear in 860 00:40:37,430 --> 00:40:32,960 mind that radioactive splitting of water 861 00:40:40,790 --> 00:40:37,440 does not add to the net processes that 862 00:40:43,070 --> 00:40:40,800 we see in these profiles because oxygens 863 00:40:45,109 --> 00:40:43,080 created at the same time as hydrogen so 864 00:40:46,910 --> 00:40:45,119 you're creating oxidant the same time 865 00:40:50,960 --> 00:40:46,920 you're creating reductant when you have 866 00:40:52,820 --> 00:40:50,970 radiolysis of water so in a sense we can 867 00:40:55,340 --> 00:40:52,830 use these profiles simply as a measure 868 00:40:56,900 --> 00:40:55,350 of the organic fueled respiration what 869 00:40:59,840 --> 00:40:56,910 you're seeing is that organic fueled 870 00:41:01,849 --> 00:40:59,850 respiration nearly stops within the 871 00:41:05,780 --> 00:41:01,859 first meter of the sediment then goes to 872 00:41:11,420 --> 00:41:05,790 essentially zero or very close to zero 873 00:41:12,940 --> 00:41:11,430 in the heart of the gyre and if you 874 00:41:15,440 --> 00:41:12,950 think back to what I showed you before 875 00:41:17,840 --> 00:41:15,450 you'll remember that concentrations 876 00:41:19,370 --> 00:41:17,850 sorry I'm jumping ahead to see if I had 877 00:41:21,320 --> 00:41:19,380 another slide you remember that 878 00:41:23,900 --> 00:41:21,330 concentrations of cells in this region 879 00:41:25,130 --> 00:41:23,910 were three orders of magnitude less than 880 00:41:27,109 --> 00:41:25,140 the average so we're seeing about a 881 00:41:29,000 --> 00:41:27,119 thousand cells per cubic centimeter in 882 00:41:31,550 --> 00:41:29,010 most of these sediments the range of 883 00:41:33,349 --> 00:41:31,560 10,000 to a thousand and so one of the 884 00:41:35,780 --> 00:41:33,359 things we'll be pursuing over the next 885 00:41:37,700 --> 00:41:35,790 year it's testing whether or not those 886 00:41:40,550 --> 00:41:37,710 1000 to 10,000 cells per cubic 887 00:41:42,980 --> 00:41:40,560 centimeter are likely to be supported 888 00:41:46,130 --> 00:41:42,990 principally by the radioactive splitting 889 00:41:51,770 --> 00:41:46,140 of the pore water here instead of by the 890 00:41:53,330 --> 00:41:51,780 Buried organic matter and with that I'll 891 00:41:58,640 --> 00:41:53,340 bring this to a close and answer 892 00:42:01,849 --> 00:41:58,650 questions Steve thank you very much that 893 00:42:03,740 --> 00:42:01,859 was quite fascinating I think I'll ask 894 00:42:06,110 --> 00:42:03,750 the first question and 895 00:42:09,560 --> 00:42:06,120 if others would raise their hands in the 896 00:42:13,280 --> 00:42:09,570 meanwhile on the the chat side of WebEx 897 00:42:16,580 --> 00:42:13,290 will then go around the loop this this 898 00:42:20,270 --> 00:42:16,590 whole idea of thermodynamic cooperation 899 00:42:22,730 --> 00:42:20,280 between different groups of organisms so 900 00:42:24,850 --> 00:42:22,740 that you have metabolisms coexisting 901 00:42:27,290 --> 00:42:24,860 that you wouldn't have normally thought 902 00:42:28,610 --> 00:42:27,300 coexist is sort of fascinating it 903 00:42:30,830 --> 00:42:28,620 reminds me a bit of the anaerobic 904 00:42:34,040 --> 00:42:30,840 oxidation of methane where perhaps 905 00:42:35,750 --> 00:42:34,050 that's also going on as well so given 906 00:42:37,940 --> 00:42:35,760 that you have another very prominent 907 00:42:41,000 --> 00:42:37,950 example that may actually apply to a 908 00:42:45,200 --> 00:42:41,010 very large segment of the sea floor 909 00:42:47,510 --> 00:42:45,210 surface I'm wondering how much do you 910 00:42:50,690 --> 00:42:47,520 think might you speculate remains to be 911 00:42:53,290 --> 00:42:50,700 discovered are we going to discover a 912 00:42:57,140 --> 00:42:53,300 lot more of these thermodynamic 913 00:42:59,420 --> 00:42:57,150 cooperations that yield metabolisms or 914 00:43:01,750 --> 00:42:59,430 coexistence of metabolisms that we 915 00:43:04,490 --> 00:43:01,760 wouldn't otherwise have expected and 916 00:43:08,000 --> 00:43:04,500 should this kind of thermodynamic 917 00:43:10,040 --> 00:43:08,010 cooperation open up our ideas about what 918 00:43:15,200 --> 00:43:10,050 might be possible on another planet 919 00:43:17,180 --> 00:43:15,210 let's say Mars that's a good series of 920 00:43:19,220 --> 00:43:17,190 questions and I'm going to start by 921 00:43:21,140 --> 00:43:19,230 saying you're you're right this many 922 00:43:23,540 --> 00:43:21,150 respects resembles the situation with an 923 00:43:25,490 --> 00:43:23,550 aerobic oxidation of methane in fact 924 00:43:29,690 --> 00:43:25,500 work that Tory holer did particularly in 925 00:43:31,610 --> 00:43:29,700 his thesis provides a sort of guide if 926 00:43:34,250 --> 00:43:31,620 you will to this sort of behavior where 927 00:43:36,470 --> 00:43:34,260 he first estimated free energy yields in 928 00:43:38,690 --> 00:43:36,480 relatively shallow sediments for that 929 00:43:41,300 --> 00:43:38,700 process so you can think of this in a 930 00:43:44,390 --> 00:43:41,310 way as an extension of that of that idea 931 00:43:45,860 --> 00:43:44,400 into other processes and into deeper 932 00:43:53,540 --> 00:43:45,870 sediments and much longer periods of 933 00:43:56,770 --> 00:43:53,550 time in a way the aom example and the 934 00:44:00,910 --> 00:43:56,780 example I gave are both extensions of an 935 00:44:05,030 --> 00:44:00,920 older recognition which is that 936 00:44:10,280 --> 00:44:05,040 organisms feed each other you know for 937 00:44:13,010 --> 00:44:10,290 example it's it's well known that the 938 00:44:15,260 --> 00:44:13,020 sorts of organisms that undertake redox 939 00:44:16,520 --> 00:44:15,270 activities like sulfate reduction and 940 00:44:20,230 --> 00:44:16,530 iron reduction 941 00:44:23,630 --> 00:44:20,240 in anoxic sediments rely ultimately on 942 00:44:25,850 --> 00:44:23,640 fermentation of organic matter for their 943 00:44:28,310 --> 00:44:25,860 food in sort of typical swamp sediments 944 00:44:30,860 --> 00:44:28,320 so it is so you can think of this as a 945 00:44:32,870 --> 00:44:30,870 way of formalizing that that older 946 00:44:38,930 --> 00:44:32,880 microbiological recognition and putting 947 00:44:41,390 --> 00:44:38,940 it in sort of a thermodynamic basis and 948 00:44:42,710 --> 00:44:41,400 I think we will see a lot more of it as 949 00:44:45,440 --> 00:44:42,720 people begin to think in that more 950 00:44:47,000 --> 00:44:45,450 explicitly thermodynamic way one of the 951 00:44:49,430 --> 00:44:47,010 things that I'm not going to get into 952 00:44:51,770 --> 00:44:49,440 too much detail here but what we've seen 953 00:44:53,990 --> 00:44:51,780 in in our more recent calculations are 954 00:44:56,360 --> 00:44:54,000 that processes that don't even occur in 955 00:44:58,400 --> 00:44:56,370 the surface world because the free 956 00:45:00,770 --> 00:44:58,410 energies don't allow it actually occur 957 00:45:02,330 --> 00:45:00,780 in the in the subsurface world because 958 00:45:04,430 --> 00:45:02,340 in situ free energies are very different 959 00:45:08,840 --> 00:45:04,440 in the subsurface than they are in the 960 00:45:10,580 --> 00:45:08,850 surface and so there are interactions in 961 00:45:12,050 --> 00:45:10,590 the nitrogen cycle for example that you 962 00:45:14,960 --> 00:45:12,060 won't see in the service world then here 963 00:45:16,850 --> 00:45:14,970 to occur in the subsurface and I suspect 964 00:45:18,400 --> 00:45:16,860 that if people were to move back out of 965 00:45:21,110 --> 00:45:18,410 the subsurface into the water column 966 00:45:23,150 --> 00:45:21,120 particularly in anoxic sediments we 967 00:45:27,860 --> 00:45:23,160 would see these rules apply there as 968 00:45:30,290 --> 00:45:27,870 well and by extension if we were to 969 00:45:34,130 --> 00:45:30,300 search for these processes on other 970 00:45:36,320 --> 00:45:34,140 planets I suspect or other bodies if 971 00:45:37,820 --> 00:45:36,330 there's life there we would find that 972 00:45:39,080 --> 00:45:37,830 they would follow similar rules if the 973 00:45:43,240 --> 00:45:39,090 environments are stable enough for 974 00:45:46,610 --> 00:45:43,250 example if there is an anoxic community 975 00:45:49,460 --> 00:45:46,620 beneath the ice of Europa or beneath the 976 00:45:52,310 --> 00:45:49,470 surface of Mars one would expect that 977 00:45:54,770 --> 00:45:52,320 over relatively geologically short 978 00:45:59,810 --> 00:45:54,780 periods of time you'd reach these sorts 979 00:46:01,730 --> 00:45:59,820 of community equilibria if you will and 980 00:46:04,700 --> 00:46:01,740 one of the things that they're there are 981 00:46:08,030 --> 00:46:04,710 complications in this that that 982 00:46:10,640 --> 00:46:08,040 potentially make it even deeper interest 983 00:46:14,120 --> 00:46:10,650 for example you can imagine a system 984 00:46:16,100 --> 00:46:14,130 where iron reducers oxidized sulfur and 985 00:46:18,140 --> 00:46:16,110 then sulfur reducers oxidize an organic 986 00:46:20,060 --> 00:46:18,150 matter and the iron reducers don't do 987 00:46:22,460 --> 00:46:20,070 the organic matter directly well in that 988 00:46:25,400 --> 00:46:22,470 case you create an electron shuttle if 989 00:46:27,530 --> 00:46:25,410 you will where you can actually sustain 990 00:46:29,620 --> 00:46:27,540 more organisms than with the same amount 991 00:46:31,269 --> 00:46:29,630 of energy but the iron reducer 992 00:46:34,480 --> 00:46:31,279 the sulfur reducers both going for the 993 00:46:35,769 --> 00:46:34,490 organic matter we've not observed that 994 00:46:37,930 --> 00:46:35,779 in any of these systems we haven't 995 00:46:39,789 --> 00:46:37,940 looked for it either so it's possible to 996 00:46:43,480 --> 00:46:39,799 imagine ways of not only sustaining a 997 00:46:45,009 --> 00:46:43,490 more richer community metabolically but 998 00:46:46,480 --> 00:46:45,019 sustaining a community that uses its 999 00:46:49,749 --> 00:46:46,490 resources much more efficiently and 1000 00:46:53,470 --> 00:46:49,759 sustains a larger biomass I'll stop 1001 00:46:59,499 --> 00:46:53,480 there okay we have a question from Penn 1002 00:47:01,569 --> 00:46:59,509 State hi Steve Jim casting I thought the 1003 00:47:04,299 --> 00:47:01,579 most provocative thing you said was it's 1004 00:47:08,049 --> 00:47:04,309 oceanic sulfate controlled atmospheric 1005 00:47:11,380 --> 00:47:08,059 co2 and climate and uh when I give my 1006 00:47:14,259 --> 00:47:11,390 talk on climate I usually emphasize that 1007 00:47:17,109 --> 00:47:14,269 co2 is more controlled by the inorganic 1008 00:47:19,630 --> 00:47:17,119 carbon cycle the carbonate silicates 1009 00:47:21,579 --> 00:47:19,640 cycle and that the organic carbon cycle 1010 00:47:25,799 --> 00:47:21,589 can't really do it because it buffers 1011 00:47:29,440 --> 00:47:25,809 oxygen what are your thoughts on that 1012 00:47:31,120 --> 00:47:29,450 and that's that's the that's usual 1013 00:47:33,400 --> 00:47:31,130 perspective and it's a it's a very good 1014 00:47:37,569 --> 00:47:33,410 one the the easiest way to put the 1015 00:47:40,720 --> 00:47:37,579 control here is that to step aside from 1016 00:47:42,789 --> 00:47:40,730 the one problem with the salt with 1017 00:47:44,470 --> 00:47:42,799 sulfate reduction as a control is you 1018 00:47:47,049 --> 00:47:44,480 know you're creating DIC at the same 1019 00:47:49,089 --> 00:47:47,059 time that you're removing sulfate so in 1020 00:47:53,980 --> 00:47:49,099 a sense you're replacing an anion with 1021 00:47:57,549 --> 00:47:53,990 another anion and so the effect on it's 1022 00:47:59,650 --> 00:47:57,559 more nearly a zero-sum game there then I 1023 00:48:01,420 --> 00:47:59,660 presented it at colloquially but it's 1024 00:48:03,880 --> 00:48:01,430 it's a more pure case where you look at 1025 00:48:07,599 --> 00:48:03,890 safe pyrite oxidation where you start 1026 00:48:09,249 --> 00:48:07,609 with iron sulfide if you oxidize that 1027 00:48:12,190 --> 00:48:09,259 and you get it you get an oxidized iron 1028 00:48:13,690 --> 00:48:12,200 that doesn't go anywhere and you get an 1029 00:48:16,329 --> 00:48:13,700 oxidized sulfur that goes into the 1030 00:48:21,099 --> 00:48:16,339 aqueous system that's a strong acid and 1031 00:48:23,559 --> 00:48:21,109 it's going to drive off co2 so so the 1032 00:48:27,819 --> 00:48:23,569 cleanest way of imaginating of imagining 1033 00:48:31,329 --> 00:48:27,829 this operating would be to essentially 1034 00:48:35,190 --> 00:48:31,339 just change your rates of precipitation 1035 00:48:37,240 --> 00:48:35,200 and oxidation of metal sulfides and 1036 00:48:40,960 --> 00:48:37,250 through the alkalinity system it will 1037 00:48:47,569 --> 00:48:44,210 Lee Kump is here Lee do you want to have 1038 00:48:49,370 --> 00:48:47,579 anything hey how you doing well I mean I 1039 00:48:50,720 --> 00:48:49,380 guess part it on the weathering side it 1040 00:48:53,299 --> 00:48:50,730 depends what happens to the protons 1041 00:48:54,859 --> 00:48:53,309 right and so there's a big a lot of 1042 00:48:57,170 --> 00:48:54,869 interest I've been seeing these days and 1043 00:48:59,509 --> 00:48:57,180 looking at pyrite induced weathering of 1044 00:49:03,650 --> 00:48:59,519 silicates for example and so if those 1045 00:49:04,910 --> 00:49:03,660 protons are are taken up during silicate 1046 00:49:06,529 --> 00:49:04,920 weathering before they ever made to the 1047 00:49:09,769 --> 00:49:06,539 ocean then you get sulfate going in for 1048 00:49:11,480 --> 00:49:09,779 sure but the but the but the protons are 1049 00:49:13,730 --> 00:49:11,490 actually being neutralized on land and 1050 00:49:15,589 --> 00:49:13,740 so then it goes back into Jim's camp so 1051 00:49:17,180 --> 00:49:15,599 I think part of it on the pirate 1052 00:49:19,730 --> 00:49:17,190 oxidation side depends on the fate of 1053 00:49:22,160 --> 00:49:19,740 those protons now on the on the flip 1054 00:49:25,160 --> 00:49:22,170 side the net sulfate reduction and 1055 00:49:27,200 --> 00:49:25,170 barrel of barrel of pyrite there you 1056 00:49:28,730 --> 00:49:27,210 know that's a sort of like a proxy for 1057 00:49:31,460 --> 00:49:28,740 organic carbon burial so there I think 1058 00:49:34,009 --> 00:49:31,470 you have a co2 driver associated with 1059 00:49:35,539 --> 00:49:34,019 that with that very loop i right but it 1060 00:49:37,670 --> 00:49:35,549 does have implications for oxygen as 1061 00:49:41,480 --> 00:49:37,680 well and so all you need to think about 1062 00:49:43,640 --> 00:49:41,490 that yes usually co2 driven thing that 1063 00:49:45,380 --> 00:49:43,650 that is based on organic carbon burial 1064 00:49:47,150 --> 00:49:45,390 you have to worry about what what what's 1065 00:49:51,109 --> 00:49:47,160 the fate of that oxygen did you drive up 1066 00:49:53,359 --> 00:49:51,119 an 02 pulse with the co2 draw down yeah 1067 00:49:56,269 --> 00:49:53,369 it is you're well aware it's both of you 1068 00:50:00,349 --> 00:49:56,279 are well aware people have often looked 1069 00:50:02,319 --> 00:50:00,359 at sulfur in terms of oxygen sinks it's 1070 00:50:05,930 --> 00:50:02,329 sort of an extension of a the classic 1071 00:50:07,370 --> 00:50:05,940 burner type approach I find it 1072 00:50:12,499 --> 00:50:07,380 interesting that people rarely look at 1073 00:50:18,779 --> 00:50:12,509 the alkalinity side of it okay we have a 1074 00:50:26,679 --> 00:50:24,459 Carnegie are you there yeah hi for 1075 00:50:28,839 --> 00:50:26,689 sukkos from Carnegie have a question 1076 00:50:35,769 --> 00:50:28,849 regarding do see have you measured you 1077 00:50:38,529 --> 00:50:35,779 seeing these segments we do measure do 1078 00:50:40,390 --> 00:50:38,539 see I can't right offhand remember any 1079 00:50:41,969 --> 00:50:40,400 numbers for you when we measure do see 1080 00:50:43,859 --> 00:50:41,979 and sometimes we also actually measure 1081 00:50:47,199 --> 00:50:43,869 classes of do see for example 1082 00:50:50,529 --> 00:50:47,209 carbohydrates amino acids etc does in 1083 00:50:52,209 --> 00:50:50,539 dissolve form the DLC of course is 1084 00:50:53,499 --> 00:50:52,219 always dissolved but I'm Clark trying to 1085 00:50:54,819 --> 00:50:53,509 clarify the carbohydrates and amino 1086 00:50:58,269 --> 00:50:54,829 acids we look at those in dissolved form 1087 00:51:02,919 --> 00:50:58,279 also do you have a question specifically 1088 00:51:05,919 --> 00:51:02,929 about the DLC so I'm having issues with 1089 00:51:06,819 --> 00:51:05,929 my sound so it's okay it's okay I don't 1090 00:51:11,919 --> 00:51:06,829 kind of don't know what we're talking 1091 00:51:17,439 --> 00:51:11,929 about okay we have a question from 1092 00:51:19,359 --> 00:51:17,449 Indiana to the morning handsome 15 if 1093 00:51:21,640 --> 00:51:19,369 you want to find out what is the 1094 00:51:24,939 --> 00:51:21,650 contribution of radiologically provide 1095 00:51:27,120 --> 00:51:24,949 energy in contrast to organic matter in 1096 00:51:29,589 --> 00:51:27,130 deep-sea sediments have you looked at 1097 00:51:32,919 --> 00:51:29,599 horizons where you have a dilution of 1098 00:51:35,349 --> 00:51:32,929 settlement by tephra in those intervals 1099 00:51:39,909 --> 00:51:35,359 you might expect less organic material 1100 00:51:43,239 --> 00:51:39,919 but more realistic energy and do you 1101 00:51:45,519 --> 00:51:43,249 have maybe a blip in bacterial 1102 00:51:52,749 --> 00:51:45,529 abundances at the margins of his temper 1103 00:51:56,409 --> 00:51:52,759 layers or in this association we haven't 1104 00:52:00,489 --> 00:51:56,419 specifically looked at this question of 1105 00:52:02,919 --> 00:52:00,499 tephra vs normal sediments in the main 1106 00:52:04,989 --> 00:52:02,929 reason for that is that the 1107 00:52:06,819 --> 00:52:04,999 concentration of organic matter is you 1108 00:52:10,779 --> 00:52:06,829 go from the continental margins to the 1109 00:52:12,699 --> 00:52:10,789 middle of the gyre varies by an 1110 00:52:15,779 --> 00:52:12,709 extraordinary amount you know we're 1111 00:52:18,189 --> 00:52:15,789 talking orders of magnitude and so 1112 00:52:20,109 --> 00:52:18,199 essentially you can take a grab sample 1113 00:52:24,669 --> 00:52:20,119 of sediment from the middle of the gyre 1114 00:52:30,069 --> 00:52:24,679 and have an essentially organic free 1115 00:52:31,180 --> 00:52:30,079 sample for comparison and this allows us 1116 00:52:33,819 --> 00:52:31,190 to use thou 1117 00:52:35,170 --> 00:52:33,829 of kilometers distance for controlling 1118 00:52:38,800 --> 00:52:35,180 our system instead of worrying about 1119 00:52:40,599 --> 00:52:38,810 centimeters I don't know if that answers 1120 00:52:41,800 --> 00:52:40,609 you yeah I'm answering your question by 1121 00:52:43,510 --> 00:52:41,810 saying no we haven't looked at the 1122 00:52:47,140 --> 00:52:43,520 temper case but that's because we have a 1123 00:52:54,760 --> 00:52:47,150 very big Geographic case that that we're 1124 00:52:59,290 --> 00:52:54,770 looking at thanks a lot you know okay we 1125 00:53:02,470 --> 00:52:59,300 have a question from Goddard hi Steve 1126 00:53:05,380 --> 00:53:02,480 it's mike boomer here I like I was a 1127 00:53:07,960 --> 00:53:05,390 nice talk I enjoyed that one has to be a 1128 00:53:09,730 --> 00:53:07,970 quick question about the balance of 1129 00:53:12,450 --> 00:53:09,740 reductants to oxidants in the 1130 00:53:15,309 --> 00:53:12,460 radiologist radiolysis dominated regime 1131 00:53:18,460 --> 00:53:15,319 and that depends strongly on the 1132 00:53:21,250 --> 00:53:18,470 tortuosity of the medium since molecular 1133 00:53:23,500 --> 00:53:21,260 hydrogen is much more mobile than like 1134 00:53:26,950 --> 00:53:23,510 their oxygen squeeze through tighter 1135 00:53:29,140 --> 00:53:26,960 spaces if you like I think that it would 1136 00:53:33,510 --> 00:53:29,150 escape more readily and leaving the 1137 00:53:36,880 --> 00:53:33,520 medium relatively Oxford which oxidizes 1138 00:53:38,680 --> 00:53:36,890 yeah it depends on you're absolutely 1139 00:53:41,950 --> 00:53:38,690 right the hydrogen should escape more 1140 00:53:43,270 --> 00:53:41,960 easily in this circumstances we're 1141 00:53:47,620 --> 00:53:43,280 looking at here we're essentially 1142 00:53:49,089 --> 00:53:47,630 looking at sediment thicknesses on this 1143 00:53:50,800 --> 00:53:49,099 recent cruise the deepest sediment 1144 00:53:54,130 --> 00:53:50,810 record was about eight meters and the 1145 00:53:58,420 --> 00:53:54,140 deepest sediment piles that we cord into 1146 00:54:01,720 --> 00:53:58,430 or around 130 meters okay so we're 1147 00:54:06,490 --> 00:54:01,730 essentially looking for diffusive 1148 00:54:10,030 --> 00:54:06,500 distances that are in the shortest 1149 00:54:12,099 --> 00:54:10,040 systems sure in the shortest distance 1150 00:54:13,780 --> 00:54:12,109 going to say halfway through the 1151 00:54:15,970 --> 00:54:13,790 sediment column to the surface or to the 1152 00:54:18,069 --> 00:54:15,980 basement below it could be as little as 1153 00:54:20,500 --> 00:54:18,079 two and a half meters where this 1154 00:54:24,569 --> 00:54:20,510 sediments really thin or in another 1155 00:54:28,660 --> 00:54:24,579 system it could be as much as 70 meters 1156 00:54:30,400 --> 00:54:28,670 so if you've got a dead system where the 1157 00:54:34,480 --> 00:54:30,410 hydrogen or the oxygen aren't being 1158 00:54:36,250 --> 00:54:34,490 utilized you would expect your steady 1159 00:54:39,190 --> 00:54:36,260 state concentrations of those two 1160 00:54:41,290 --> 00:54:39,200 products to be different because the 1161 00:54:45,090 --> 00:54:41,300 hydrogen's escaping more readily you'd 1162 00:54:50,560 --> 00:54:47,560 but in a system where you've got 1163 00:54:53,170 --> 00:54:50,570 organisms cropping it typically they 1164 00:54:56,830 --> 00:54:53,180 crop the hydrogen you know in time 1165 00:54:58,990 --> 00:54:56,840 scales of minutes or less and the the 1166 00:55:00,820 --> 00:54:59,000 distances over which the hydrogen must 1167 00:55:04,680 --> 00:55:00,830 diffuse is again meters to tens of 1168 00:55:08,440 --> 00:55:04,690 meters so that will take many years to 1169 00:55:12,730 --> 00:55:08,450 to thousands of years has anyone 1170 00:55:15,640 --> 00:55:12,740 actually done any kind of measurements 1171 00:55:18,400 --> 00:55:15,650 of net gas escaped from these media to 1172 00:55:20,620 --> 00:55:18,410 identify use that as a marker for the 1173 00:55:23,050 --> 00:55:20,630 kinds of biology that's going on whether 1174 00:55:27,310 --> 00:55:23,060 it's driven radial radiologically as 1175 00:55:29,740 --> 00:55:27,320 opposed to what are the mechanisms well 1176 00:55:32,950 --> 00:55:29,750 we took samples on our recent cruise we 1177 00:55:36,130 --> 00:55:32,960 measure hydrogen routinely and what we 1178 00:55:38,560 --> 00:55:36,140 found was that hydrogen is always below 1179 00:55:43,480 --> 00:55:38,570 our detection limit in our detection 1180 00:55:44,980 --> 00:55:43,490 limit is a typically two or three orders 1181 00:55:47,860 --> 00:55:44,990 of magnitude lower than the 1182 00:55:49,360 --> 00:55:47,870 concentration you'd expect if the 1183 00:55:50,800 --> 00:55:49,370 sediment is as radioactive as the 1184 00:55:56,530 --> 00:55:50,810 sediment we've looked at in the past and 1185 00:55:59,470 --> 00:55:56,540 the system is dead okay we also took 1186 00:56:02,200 --> 00:55:59,480 samples for measuring helium 1187 00:56:03,880 --> 00:56:02,210 concentrations to get a measure of the 1188 00:56:07,210 --> 00:56:03,890 Alpha flux out of the sediment if you 1189 00:56:10,330 --> 00:56:07,220 will and it's steady state those helium 1190 00:56:12,850 --> 00:56:10,340 concentrations the helium flux should be 1191 00:56:14,920 --> 00:56:12,860 equal to the helium bombardment of water 1192 00:56:16,120 --> 00:56:14,930 because obviously any alpha radiation 1193 00:56:18,730 --> 00:56:16,130 that didn't get out of the mineral 1194 00:56:21,280 --> 00:56:18,740 grains won't be in the water to diffuse 1195 00:56:22,840 --> 00:56:21,290 out so we're hoping to use that as a 1196 00:56:24,970 --> 00:56:22,850 check if you will both of those are 1197 00:56:26,380 --> 00:56:24,980 variations on things that the indiana 1198 00:56:29,440 --> 00:56:26,390 princeton team has done in there deep 1199 00:56:30,670 --> 00:56:29,450 mines one difference being that 1200 00:56:35,680 --> 00:56:30,680 effectively they're measuring 1201 00:56:37,870 --> 00:56:35,690 concentrations there and they don't have 1202 00:56:39,010 --> 00:56:37,880 the advantage of depth that we that we 1203 00:56:42,190 --> 00:56:39,020 have where we can actually calculate 1204 00:56:44,650 --> 00:56:42,200 fluxing directly using transport models 1205 00:56:48,360 --> 00:56:44,660 but but we're measuring the same 1206 00:56:48,370 --> 00:56:55,380 okay 1207 00:57:02,250 --> 00:56:59,579 well thank you Mike it looks like that's 1208 00:57:05,789 --> 00:57:02,260 all that's all the questions I just 1209 00:57:07,920 --> 00:57:05,799 wanted to make one other comment and if 1210 00:57:09,390 --> 00:57:07,930 anybody has a last-minute question 1211 00:57:11,609 --> 00:57:09,400 please raise your hand while I'm doing 1212 00:57:13,349 --> 00:57:11,619 so otherwise we'll sign off and that is 1213 00:57:16,289 --> 00:57:13,359 that one of the things that we have been 1214 00:57:19,440 --> 00:57:16,299 doing is working to improve the quality 1215 00:57:21,720 --> 00:57:19,450 of our archives of these seminars and 1216 00:57:24,630 --> 00:57:21,730 others and so I just want to remind you 1217 00:57:26,940 --> 00:57:24,640 that all the director seminars are 1218 00:57:29,220 --> 00:57:26,950 archived the archives are available on 1219 00:57:31,950 --> 00:57:29,230 our website one of the things we have 1220 00:57:34,799 --> 00:57:31,960 not had archived is the video feed what 1221 00:57:37,289 --> 00:57:34,809 we've had is the audio feed and the 1222 00:57:40,650 --> 00:57:37,299 WebEx or at least the slides I should 1223 00:57:43,079 --> 00:57:40,660 say and we now have an archive that 1224 00:57:46,620 --> 00:57:43,089 includes the video feed so you can see 1225 00:57:49,410 --> 00:57:46,630 Steve's handsome face hopefully when we 1226 00:57:51,990 --> 00:57:49,420 archive this we will maintain both 1227 00:57:54,509 --> 00:57:52,000 options however because the archived 1228 00:57:56,759 --> 00:57:54,519 version that has the video feed is a 1229 00:57:58,920 --> 00:57:56,769 much larger file size and it's going to 1230 00:58:01,710 --> 00:57:58,930 be inconvenient for anybody who doesn't 1231 00:58:03,960 --> 00:58:01,720 have ready access to a fairly broadband 1232 00:58:06,809 --> 00:58:03,970 link so we will have both options 1233 00:58:09,120 --> 00:58:06,819 available but I just wanted to let you 1234 00:58:11,160 --> 00:58:09,130 all know that and let me just ask if 1235 00:58:13,319 --> 00:58:11,170 there are any last questions from anyone 1236 00:58:19,680 --> 00:58:13,329 around the net like Arizona has a 1237 00:58:22,670 --> 00:58:19,690 question Arizona go ahead please hi dr. 1238 00:58:26,009 --> 00:58:22,680 danse Joe Russell hi Joe how are you 1239 00:58:28,609 --> 00:58:26,019 good I was just wondering it's sort of a 1240 00:58:30,749 --> 00:58:28,619 method question really is uh how do you 1241 00:58:32,880 --> 00:58:30,759 since you're taking these core samples 1242 00:58:34,440 --> 00:58:32,890 from the ocean how do you make sure that 1243 00:58:35,880 --> 00:58:34,450 like it's not contaminated by ocean 1244 00:58:38,640 --> 00:58:35,890 water and obviously there's you know a 1245 00:58:40,829 --> 00:58:38,650 lot of microorganisms in ocean water so 1246 00:58:42,120 --> 00:58:40,839 exactly how do you you know did you 1247 00:58:44,579 --> 00:58:42,130 account for that you have to account for 1248 00:58:48,059 --> 00:58:44,589 that at all yeah that's a very good 1249 00:58:50,190 --> 00:58:48,069 question when we're drilling it's easier 1250 00:58:51,390 --> 00:58:50,200 to do than when we're simply piston 1251 00:58:55,499 --> 00:58:51,400 coring is we were on the most recent 1252 00:58:57,960 --> 00:58:55,509 cruise what we do when we're drilling is 1253 00:59:01,079 --> 00:58:57,970 we we do two things when we put a little 1254 00:59:04,799 --> 00:59:01,089 bag Roy pack bag with fluorescent 1255 00:59:07,640 --> 00:59:04,809 cereals into the cutting shoe so when 1256 00:59:11,870 --> 00:59:07,650 the piston drives the 1257 00:59:14,300 --> 00:59:11,880 the horror forward it ruptures the bag 1258 00:59:17,440 --> 00:59:14,310 and those those microspheres all just 1259 00:59:19,820 --> 00:59:17,450 stream up the sides and into the core 1260 00:59:22,220 --> 00:59:19,830 I'm not real fond of that technique 1261 00:59:23,720 --> 00:59:22,230 because it tends to disturb the core but 1262 00:59:24,890 --> 00:59:23,730 microbiologists like it because they can 1263 00:59:28,340 --> 00:59:24,900 see little glowing beads and their 1264 00:59:30,470 --> 00:59:28,350 microscope slides the technique that we 1265 00:59:33,590 --> 00:59:30,480 use its quantifiable and more precise 1266 00:59:39,040 --> 00:59:33,600 and more accurate in a sense except as a 1267 00:59:44,570 --> 00:59:42,800 very easily measured chemical into the 1268 00:59:47,030 --> 00:59:44,580 drilling fluid and circulate it through 1269 00:59:49,570 --> 00:59:47,040 the system it's a perfluorocarbon tracer 1270 00:59:51,590 --> 00:59:49,580 that we can measure at the ppt level and 1271 00:59:54,050 --> 00:59:51,600 because we know the rate at which we're 1272 00:59:56,030 --> 00:59:54,060 metering it into the drilling fluid when 1273 00:59:57,410 --> 00:59:56,040 we find it in in the core we know 1274 00:59:59,990 --> 00:59:57,420 exactly how much contamination has 1275 01:00:02,450 --> 01:00:00,000 occurred and incidentally the drilling 1276 01:00:04,790 --> 01:00:02,460 fluid is surface seawater so that's how 1277 01:00:07,040 --> 01:00:04,800 we do it when we're drilling there are 1278 01:00:11,540 --> 01:00:07,050 much less subtle approaches at you that 1279 01:00:13,490 --> 01:00:11,550 people have used for example you can use 1280 01:00:15,980 --> 01:00:13,500 the difference in chemistry between the 1281 01:00:18,200 --> 01:00:15,990 surface water and the pore water as a 1282 01:00:19,540 --> 01:00:18,210 proxy for contamination that's usually 1283 01:00:22,670 --> 01:00:19,550 only picking out really gross 1284 01:00:24,710 --> 01:00:22,680 contamination so for example you could 1285 01:00:27,530 --> 01:00:24,720 use the occurrence of oxygen and anoxic 1286 01:00:29,480 --> 01:00:27,540 sediments as a measure or the occurrence 1287 01:00:31,340 --> 01:00:29,490 of sulfate and sulfate free sediment as 1288 01:00:34,610 --> 01:00:31,350 a measure but the perfluorocarbon tracer 1289 01:00:36,260 --> 01:00:34,620 is much much more sensitive so 1290 01:00:38,900 --> 01:00:36,270 essentially our detection limit for the 1291 01:00:44,990 --> 01:00:38,910 pft is equal to somewhere between 1 and 1292 01:00:46,550 --> 01:00:45,000 10 cells of contaminating microbe which 1293 01:00:48,680 --> 01:00:46,560 is about as low as anyone's gotten it 1294 01:00:56,260 --> 01:00:48,690 although there are hypothetically ways 1295 01:01:03,740 --> 01:00:59,810 thank you thank you you're welcome 1296 01:01:06,080 --> 01:01:03,750 thanks for your question okay Steve I 1297 01:01:09,260 --> 01:01:06,090 think that's the end of the question so 1298 01:01:11,930 --> 01:01:09,270 let us all thank you again for really 1299 01:01:13,880 --> 01:01:11,940 fascinating and stimulating provocative