Abstract Details
(2020) Key Findings from the Comprehensive Review of Natural Hydrogen
Zgonnik V
https://doi.org/10.46427/gold2020.3082
08f: Room 3, Tuesday 23rd June 05:36 - 05:39
Viacheslav Zgonnik
View abstracts at 2 conferences in series
Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.
Submitted by Barbara Sherwood Lollar on Saturday 20th June 19:00
Thank you for this great integration of data from east and west! One of the biggest challenges in quantifying H2 flux and flow is not only understanding sources and production rates – but the traditionally much more difficult to quantify H2 sinks (both abiotic and biotic). Can you comment on the best tools/questions to take the field forward to determine that balance of sources/sinks? Thank you – question posed by Barbara Sherwood Lollar (barbara.sherwoodlollar@utoronto.ca)
Thank you! Your works made a significant part of the review! Indeed, sinks are more difficult to quantify due to their nature. In my opinion, not all sinks are sufficiently understood yet, and more attention should be paid to characterize them. For example, reaction of hydrogen with rocks and their alteration, formation of juvenile water in such reactions, participation of geologic hydrogen in atmospheric chemistry, hydrogen escape to space, etc. Another important point to keep in mind by any researcher studying the sinks - that the consumption ratio of hydrogen could be higher than the current estimates for production rates. I.e. the numbers obtained for sinks could be greater than the current estimates for sources.
Thank you for this great integration of data from east and west! One of the biggest challenges in quantifying H2 flux and flow is not only understanding sources and production rates – but the traditionally much more difficult to quantify H2 sinks (both abiotic and biotic). Can you comment on the best tools/questions to take the field forward to determine that balance of sources/sinks? Thank you – question posed by Barbara Sherwood Lollar (barbara.sherwoodlollar@utoronto.ca)
Thank you! Your works made a significant part of the review! Indeed, sinks are more difficult to quantify due to their nature. In my opinion, not all sinks are sufficiently understood yet, and more attention should be paid to characterize them. For example, reaction of hydrogen with rocks and their alteration, formation of juvenile water in such reactions, participation of geologic hydrogen in atmospheric chemistry, hydrogen escape to space, etc. Another important point to keep in mind by any researcher studying the sinks - that the consumption ratio of hydrogen could be higher than the current estimates for production rates. I.e. the numbers obtained for sinks could be greater than the current estimates for sources.
Submitted by Jethro Sanz-Robinson on Sunday 21st June 18:53
Would you be able to provide any examples of deep-seated hydrogen sources and how much they contribute to the global hydrogen flux?
In the section 3.1 of the review you will find citations of works where authors attributed discoveries of hydrogen to a deep-seated source. Of course, such attribution remains subjective due to the lack of clear criteria to distinguish between crust hydrogen (i.e. serpentinization) and core and mantle hydrogen (deep-seated).
Would you be able to provide any examples of deep-seated hydrogen sources and how much they contribute to the global hydrogen flux?
In the section 3.1 of the review you will find citations of works where authors attributed discoveries of hydrogen to a deep-seated source. Of course, such attribution remains subjective due to the lack of clear criteria to distinguish between crust hydrogen (i.e. serpentinization) and core and mantle hydrogen (deep-seated).
Submitted by Oliver Warr on Sunday 21st June 19:30
Hi, really impressive work and I enjoyed reading the paper. I was wondering if you had any thoughts on how best we can quantify the hydrogen loss through microbial activity in the deep subsurface? In Table 25 of your paper this is currently listed as unknown. Given how much might be being produced in these environments (Sherwood Lollar et al., 2014, Warr et al., 2019) I am very interested to see how much might be being consumed, and the rates involved.
Thank you for the kind words! One of the by-products of deep subsurface is methane. In Shaefer 2016 https://doi.org/10.1126/science.aad2705 the authors argue that most of the atmospheric methane is of biogenic origin. Could it be that a portion of it is released by the deep biosphere? If we know the activity of deep methanogens (how fast is their metabolism), and if we can figure out what portion of deep biogenic methane is released to atmosphere (probably most of it is consumed on its way up), we could make an estimate for the total size of the methanogenic community in the deep subsurface. Then, if we know the ratio between methanogens and other hydrogenotrophs in the subsurface (sulfate reducers, denitrifiers, ferric iron reducers, etc) we can find a total hydrogen consumption. Finally, if we know the ratio between hydrogenotrophs and all other microorganisms living on the products of those lithoautotrophs, we could deduct a total size of the deep subsurface biosphere.
Hi, really impressive work and I enjoyed reading the paper. I was wondering if you had any thoughts on how best we can quantify the hydrogen loss through microbial activity in the deep subsurface? In Table 25 of your paper this is currently listed as unknown. Given how much might be being produced in these environments (Sherwood Lollar et al., 2014, Warr et al., 2019) I am very interested to see how much might be being consumed, and the rates involved.
Thank you for the kind words! One of the by-products of deep subsurface is methane. In Shaefer 2016 https://doi.org/10.1126/science.aad2705 the authors argue that most of the atmospheric methane is of biogenic origin. Could it be that a portion of it is released by the deep biosphere? If we know the activity of deep methanogens (how fast is their metabolism), and if we can figure out what portion of deep biogenic methane is released to atmosphere (probably most of it is consumed on its way up), we could make an estimate for the total size of the methanogenic community in the deep subsurface. Then, if we know the ratio between methanogens and other hydrogenotrophs in the subsurface (sulfate reducers, denitrifiers, ferric iron reducers, etc) we can find a total hydrogen consumption. Finally, if we know the ratio between hydrogenotrophs and all other microorganisms living on the products of those lithoautotrophs, we could deduct a total size of the deep subsurface biosphere.
Submitted by Nivea Magalhaes on Monday 22nd June 01:42
Can you provide any insight into why there is no data of H2 occurrences in South America or India (according to map in presentation)? Is it due to geological factors or just a lack of investigation?
Dear Nivea, Your question is important and the comment is mentioned in the comment in the presentation and in the original paper: the high density of placemarks across Eastern Europe and Northern Asia is due to the fact that researchers from these regions were looking for hydrogen more frequently, and not because these regions are richer in hydrogen. Hydrogen should be present in South America and India as often as at other continents. Therefore, with purposeful search it will be possible to find it.
Can you provide any insight into why there is no data of H2 occurrences in South America or India (according to map in presentation)? Is it due to geological factors or just a lack of investigation?
Dear Nivea, Your question is important and the comment is mentioned in the comment in the presentation and in the original paper: the high density of placemarks across Eastern Europe and Northern Asia is due to the fact that researchers from these regions were looking for hydrogen more frequently, and not because these regions are richer in hydrogen. Hydrogen should be present in South America and India as often as at other continents. Therefore, with purposeful search it will be possible to find it.
Sign in to ask a question.