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you

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[Music]

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hello everyone can you hear me alright

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perfect so my name is mama monster I'm a

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graduate student from Penn State

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University and I'm going to talk about

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malignant and nitrogen column addition

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to ecosystems in the Pacific Ocean and

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so as astrobiologists we are interested

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in finding life in the universe one of

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the places that we have added identify

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to be too hard where life might be

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earth-like planets but women think of

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like planets what type of life forms do

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we expect to find there we expect to

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find simple life that that can perhaps

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evolved complex lives and to intelligent

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life is this evolutionary transition

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inevitable

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while some suggest that there are

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barriers that would prevent this

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evolution and in order to start

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answering this question we can look at

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to its surface trees as a case study

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deals over a period of 4.5 billion years

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have changed has undergone dramatic

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changes from an possibly ion which ocean

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in our Qian to a sulfinic ocean in the

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protozoic and to an oxygen which of and

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in the world that we live in today and

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it was thought that the earliest

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microbes were speedily on around four

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billion years ago this followed a period

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of where where major UK TWC

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diversification happens around 500

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million years ago and there seems to be

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a long period about four billion years

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where simple life where it took from

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simple life to complex life and I'm

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finally intelligent life I was pretty

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pretty rapidly after the major UK a feat

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of diversification and so my project

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involves looking at this long period of

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seemingly evolution interfaces from

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microbes to eukaryotes transition while

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the barriers that depth even this

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transition attendez transition happening

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early on earlier on in Earth history and

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so one idea was proposed by as far as I

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know by in 2002 by Avalon by Andrew nor

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is that there were molybdenum and

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nitrogen coal imitation to porters a

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proto ZOA ecosystem and so in order to

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understand it I policies we must first

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understand the molybdenum cycling in the

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modern modern ocean today molybdenum is

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supply

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primarily to oxidative we're doing a

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continence to the modern ocean with

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concentrations of about 100 nano molar

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molybdenum is also removed from the

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ocean will have its primary sinks being

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fulfilling regions and because the earth

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has undergone dramatic geochemical

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changes to our history and because our

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multi-layered supplies to oxidative

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we're doing let's start that emotional

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considerations when the ocean will

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change as a function of oxygen

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concentration so here we can see the

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oxygen evolution where it increased

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after the great oxidation event and then

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followed up there by a second oxidation

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event multi known concentrations are

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also part to change over time being

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pretty low in the alkyne

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and an increasing slightly in the

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Pacific and finally increasing by a lot

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during the kind of a fan of every

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molybdenum as it turns out it's a pretty

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important cofactor in nitrogen fixation

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fixing enzymes such as nitrogenous and

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here we can superimpose an experimental

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nitrogen fixation limit to laboratory

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cultures and here this is so below this

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period Molina is limiting to nitrogen

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fixation and thus there potentially like

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nutrients to support the transition to a

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eukaryotic world and so the question

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here is so to judge biogeochemical

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modeling people have suggested that

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marginal constituents are about one nano

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molar in the alkene and then it

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increased about 10 nano molar in the

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Proterozoic but especially in the

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purchase order answered there are huge

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answers these with marginal

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concentrations because we don't know

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what the whether the ocean was really

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sulfide rich and how much of the ocean

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was subjected to software the conditions

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and so this is and so one proxied has

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been suggested to be useful in order to

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reconstruct seawater molybdenum

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12 time is the melindam content in

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pyrite pyrite is an iron disulfide

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mineral doing its precipitation

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molybdenum in seawater can be

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incorporated into pyrite crystal

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structure as impurities and this is

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thought this has been suggested by Ross

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Lodge and others that it can be used as

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a proxy for see what promotional

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consideration both large and I just

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produce a data set where the modern

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content of pyrite the analyzed modem

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contemporize - laser ablation

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and shown it as a function of time and

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we can see that in terms of relative

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amount that's a very low modern content

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in polite Indian with a slight increase

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in protozoic and finally a huge increase

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in the phanerozoic however there is no

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quantitative constraints on these values

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currently we are only concentrated

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considering them as relative and so what

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I want to do I wanted to do is to do

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experiments in order to devise a

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relationship between the modern content

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of pyrite and actual modern

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concentrations in water so that we can

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get quantitative quantitative

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constraints that we can compare to

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actual biological limit and so we set

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out to do this in the laboratory and to

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grow pyrite under control

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experimental conditions so we

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precipitate pyrite in this reactors that

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contain a baseline of 10 nano molar moly

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molybdenum as in the form of molybdate

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ion we added iron and sulfite together

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we tested several different conditions

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variable initial dissolve Maldon 'm as

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well as the effects of precipitation

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rate and pH - multi no content in pyrite

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pyrite was separated from the reactors

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using a sequential acid extraction I

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will measure the muslim continent pyrite

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using icp-ms

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in our baseline condition where we only

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added ferrous iron and sodium sulphide

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at pH 7 we found that the reaction was

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very slow and it never of each

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completion so you modify the baseline

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condition by adding elemental sulfur and

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by adding elemental software we actually

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increase the precipitation rate for

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precipitation rate for pyrite from we

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and we also the reaction complete

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obvious to completion we can also test

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at different multi known concentrations

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now so we tested Constitution between 10

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to about 10,000 nano molar molybdenum we

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also tested different pH so all these

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experiments were done at page 7 and this

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were done at pH 9 interestingly we found

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that pH causes and in fact the

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dissipation rate so there were slower

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precipitation at pH 9 relative to

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comparable condition at pH 7 we also

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found out that when we added hi mama

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listener

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into experiments a th9 millennium

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precipitates out in a mineral phase that

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was not associated of pyrite so we

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didn't consider this data in our in our

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study in our interpretation the

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preliminary results were very

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encouraging and that we found that the

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modern content in pyrite correlates very

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well with the initial dissolve modern

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concentration in our reactors we get an

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r-squared value of point eight three we

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did not find any significant difference

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which either precipitation rate or

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between different pH or between

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different amounts of elemental sulphur

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we do see this huge scatter which seems

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to be correlated with the amount of

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pyrite that we make in the in our ESS so

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as we make more pyrite we decrease the

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emotional content and pyrite our

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demonium iron ratio and pyrite so now

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that we have this interesting

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correlation to experimental conditions

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we wanted to see whether we can apply

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this with whether we can actually use

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this in natural system so this is the

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same plot as before our muslim continent

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pyrite versus concentration and this is

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the experimental line and so we want to

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compare this with modern pyrite where we

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have data of the whole genome content as

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well as the modern constitution in the

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water above them pyrite is one of those

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complex minerals that can form under a

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variety of conditions so the first one

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that we looked at was there isn't a

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pyrite that forms under toxic to the

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coccyx water columns this pyrite are

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formed in sediments and if all right

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somewhere along this line we also look

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at genetic pyrite by whatever form in

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the water column so this pyrite in this

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water column there can be certification

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with surface water that contains high

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marginal content and a sofa dick bottom

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water that contains lower marginal

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concentration and so that's the best

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reason for this line here this is from

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the black sea where the concentration of

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the water can change can vary between

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the bottom and surface water we also

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look at biofilm associated pyrite today

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this mode of formation of pyrite is

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where but it could have been more

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important on the early Earth so a few

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things are pop out here the first one

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being that the experimental diversity

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relationship kind of works for that

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genetic pyrite but we can see that

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there's clear overestimation there's a

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clear bias to its higher value

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especially for us in genetic and biofilm

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associated pyrite so we cannot use this

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instrument aligned directly we have to

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account for this complications access it

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in other two because we construct skew

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optimism over history and so we propose

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a couple of strategies in order to

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reconstruct see what they more than them

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so this is the modern content this is

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the data of marginal content in private

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collected to collected to later

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ablations compiled some literature's

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blew up highlights on black shales while

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original from shallow microbial cabinets

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and we have actually notice here we have

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put the marginal concentration data on

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the axis on the right and so if we use

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the data directly mol genome

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constellations in the modern ocean can

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predict it to be as high as 10,000 nano

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molar which doesn't seem to be accurate

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at all that is there is no place that

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currently has 10,000 animala molybdenum

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but one way we can try to remove this

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bias to a higher value value is to

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remove this data from sin genetic pyrite

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which which can be identified through

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the use of several geochemical proxies

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one of them being the degree of

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civilization another thing that we did

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was to use the median as the upper limit

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instead of the maximum and use the

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minimum as the lower limit so we can put

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constraints in order to try to reduce

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the bias to a higher values and so this

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is what we did so this is the median for

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the black shales

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followed by the minimum and we can

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collapse this data in order to get some

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constraints on see what the moles in

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them over time we can do the same thing

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for cabinets and we get this trend this

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trend for see what ammonium over time

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based on black shales and cognates

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00:11:10,500 --> 00:11:08,600
and so if you look here this did so this

279
00:11:13,240 --> 00:11:10,510
the data is pretty interesting in that

280
00:11:15,250 --> 00:11:13,250
so we can also impose superimpose the

281
00:11:17,650 --> 00:11:15,260
nitrogen fixation limit which is about 5

282
00:11:19,900 --> 00:11:17,660
nano molar around here and so as you can

283
00:11:20,950 --> 00:11:19,910
see the data from the Archie and suggest

284
00:11:22,900 --> 00:11:20,960
that multi necrosis

285
00:11:25,330 --> 00:11:22,910
were below the nitrogen fixation remain

286
00:11:28,330 --> 00:11:25,340
as predicted by biochemical biochemical

287
00:11:30,850 --> 00:11:28,340
models and in a modern ocean the values

288
00:11:32,620 --> 00:11:30,860
some is somewhere between 50 to 100 nano

289
00:11:36,340 --> 00:11:32,630
molar so that gave me some confidence

290
00:11:39,130 --> 00:11:36,350
that this approach might work and then

291
00:11:42,240 --> 00:11:39,140
we can compare the data to what happens

292
00:11:44,860 --> 00:11:42,250
in the Proterozoic so we get a value of

293
00:11:46,630 --> 00:11:44,870
between 5 to 50 nano molar with an

294
00:11:50,290 --> 00:11:46,640
average value of 20 nano molar

295
00:11:52,960 --> 00:11:50,300
molybdenum and so based on this simple

296
00:11:54,670 --> 00:11:52,970
of the construction well it seems that

297
00:11:57,070 --> 00:11:54,680
see what ammonium concession in the

298
00:12:00,610 --> 00:11:57,080
bottle protozoic is above the nitrogen

299
00:12:02,230 --> 00:12:00,620
fixation limit and so it cannot it may

300
00:12:04,870 --> 00:12:02,240
not be the barrier for you guys the

301
00:12:06,220 --> 00:12:04,880
evolution during this time period but of

302
00:12:08,950 --> 00:12:06,230
course we have to use the data with

303
00:12:10,810 --> 00:12:08,960
caution there's clear over estimation

304
00:12:13,510 --> 00:12:10,820
from Cincinnati and biofilm pyrite which

305
00:12:16,300 --> 00:12:13,520
we haven't fully removed because we like

306
00:12:19,120 --> 00:12:16,310
geochemical toxic data that to identify

307
00:12:20,950 --> 00:12:19,130
either both of this type of pyrite so

308
00:12:23,680 --> 00:12:20,960
perhaps uranium isotope can help us with

309
00:12:29,230 --> 00:12:23,690
some of that I and some other vbeq

310
00:12:31,240 --> 00:12:29,240
isotopes and so in summary we were

311
00:12:33,280 --> 00:12:31,250
wondering if Magnum and nitrogen

312
00:12:36,700 --> 00:12:33,290
colonization can act as a barrier to do

313
00:12:38,290 --> 00:12:36,710
to eukaryotic diversification we have

314
00:12:40,090 --> 00:12:38,300
conducted experiments in the laboratory

315
00:12:42,370 --> 00:12:40,100
that shows that the muslim continent

316
00:12:44,740 --> 00:12:42,380
private college very well with dissolved

317
00:12:46,780 --> 00:12:44,750
marginal concentrations we use the

318
00:12:49,360 --> 00:12:46,790
experimentally divided line in order to

319
00:12:51,100 --> 00:12:49,370
reconstruct yatta-mole denim and show

320
00:12:53,170 --> 00:12:51,110
that the molybdenum constellation in the

321
00:12:55,390 --> 00:12:53,180
project is potentially not limiting

322
00:12:57,160 --> 00:12:55,400
nitrogen fixation and may not be the

323
00:13:00,760 --> 00:12:57,170
barrier for eukaryotic diversification

324
00:13:02,170 --> 00:13:00,770
and finally we need more proxy more

325
00:13:04,420 --> 00:13:02,180
development of process in order to

326
00:13:05,440 --> 00:13:04,430
identify some genetic pyrite and biofilm

327
00:13:07,810 --> 00:13:05,450
associated pyrite

328
00:13:14,509 --> 00:13:07,820
so that we can use this technique more

329
00:13:17,579 --> 00:13:16,410
thanks very much we have time for a

330
00:13:27,540 --> 00:13:17,589
quick question or two while we switch

331
00:13:30,269 --> 00:13:27,550
over just a usual way too low

332
00:13:32,579 --> 00:13:30,279
molybdenum concentrations for our heal a

333
00:13:35,670 --> 00:13:32,589
lot of very important enzymes are using

334
00:13:38,790 --> 00:13:35,680
molybdenum how do you there was life

335
00:13:41,550 --> 00:13:38,800
energy more shelter how you explain that

336
00:13:44,250 --> 00:13:41,560
how they were coping good so there are

337
00:13:46,590 --> 00:13:44,260
the nitrogenous for example can have

338
00:13:48,900 --> 00:13:46,600
other different cofactors millennium is

339
00:13:51,420 --> 00:13:48,910
not the only cofactors it is certainly

340
00:13:53,790 --> 00:13:51,430
the most efficient form but iron for

341
00:13:57,990 --> 00:13:53,800
example can be substituted in depth in

342
00:13:59,610 --> 00:13:58,000
place of Magnum but another question the

343
00:14:01,590 --> 00:13:59,620
terrestrial volcanic systems that are

344
00:14:04,040 --> 00:14:01,600
producing a lot of molybdenum okay

345
00:14:07,259 --> 00:14:04,050
probably do you consider these

346
00:14:10,139 --> 00:14:07,269
molybdenum delivery in your conclusions

347
00:14:14,220 --> 00:14:10,149
or you just consider the ocean samples

348
00:14:17,400 --> 00:14:14,230
so we in this respect we apply right is

349
00:14:19,860 --> 00:14:17,410
a proxy for a seawater so we use so we

350
00:14:21,720 --> 00:14:19,870
only consider the oceanic system but not

351
00:14:26,220 --> 00:14:21,730
Dario but doesn't ya want to thank you

352
00:14:28,110 --> 00:14:26,230
thank you yep oh it's very interesting

353
00:14:30,150 --> 00:14:28,120
talk so my question is and does

354
00:14:32,579 --> 00:14:30,160
molybdenum actually sit in the lattice

355
00:14:34,560 --> 00:14:32,589
of the pirate or they the multiple

356
00:14:37,380 --> 00:14:34,570
actually present some nugget and this is

357
00:14:39,389 --> 00:14:37,390
trapped by the pirate so I think this is

358
00:14:42,569 --> 00:14:39,399
still an area of ongoing research but

359
00:14:43,050 --> 00:14:42,579
the Kevin consensus is that it is an a

360
00:14:45,750 --> 00:14:43,060
nano

361
00:14:49,040 --> 00:14:45,760
inclusion in pyrite okay yeah all right

362
00:14:55,760 --> 00:14:51,360
Brooke we have time for we're a group

363
00:14:58,350 --> 00:14:55,770
that was great talk thanks um so I

364
00:15:00,180 --> 00:14:58,360
honestly I kind of have a comment just

365
00:15:02,970 --> 00:15:00,190
to update it update the field with some

366
00:15:04,590 --> 00:15:02,980
unpublished research because it's

367
00:15:06,660 --> 00:15:04,600
interesting to me that this all kind of

368
00:15:08,970 --> 00:15:06,670
hinges around this 5-man animal are

369
00:15:11,639 --> 00:15:08,980
numbers that are you know are ales

370
00:15:14,220 --> 00:15:11,649
groups when I was a PhD student and also

371
00:15:15,240 --> 00:15:14,230
average circle came up with but but now

372
00:15:18,300 --> 00:15:15,250
that we've been doing more field

373
00:15:19,980 --> 00:15:18,310
research it's pretty hard to find a

374
00:15:21,930 --> 00:15:19,990
little bit of limited environments and I

375
00:15:24,480 --> 00:15:21,940
think some people have found them but

376
00:15:26,850 --> 00:15:24,490
they're pretty rare and most fresh

377
00:15:27,660 --> 00:15:26,860
waters have we're talking you know some

378
00:15:30,300 --> 00:15:27,670
animal

379
00:15:32,910 --> 00:15:30,310
or levels and so I just want to kind of

380
00:15:35,940 --> 00:15:32,920
I think there's a kind of caveat that

381
00:15:37,380 --> 00:15:35,950
they're not using so far we've not found

382
00:15:40,410 --> 00:15:37,390
an environment that's using an

383
00:15:42,140 --> 00:15:40,420
alternative nitrogenase so based on the

384
00:15:44,730 --> 00:15:42,150
modern we don't have evidence that

385
00:15:46,410 --> 00:15:44,740
alternative my tragedies is important

386
00:15:48,930 --> 00:15:46,420
everywhere so just when thinking about

387
00:15:50,460 --> 00:15:48,940
that vanadium question I think it's

388
00:15:53,910 --> 00:15:50,470
important to kind of constrain it with

389
00:15:56,370 --> 00:15:53,920
some some modern focus environments like

390
00:15:57,750 --> 00:15:56,380
I have to talk more yeah I agree with

391
00:15:59,610 --> 00:15:57,760
that that's what there's a lot of

392
00:16:03,480 --> 00:15:59,620
research going to at least have an