Biogeochemistry

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Question:
New Can anybody knows how to explain d-excess value of precipitation water isotopes? I calculated d-excess value using Craig's formula.
Water isotopes

Water isotopes

By Tamir Puntsag · State University of New York College of Environmental Science and Forestry

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63 How does one grind leaf samples to a fine powder for analysis by ICP-MS?
By Miranda Muller · University of the Witwatersrand

Manuel Leiva · University of California, Davis

MANUAL on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests http://www.icp-... [more]

MANUAL on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests http://www.icp-forests.org/pdf/FINAL_Foliage.pdf

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1 which is the better method to sampling nutrients in harbour area? Is it necessary to filter with GFF or not?
By Paola Rumolo · National Research Council

John Gallagher · University of Tasmania

Yes it is necessary maybe not for specific species such as nitrate or nitrite, aslthoyugh they may but some assocation with particulate as is definitl... [more]

Yes it is necessary maybe not for specific species such as nitrate or nitrite, aslthoyugh they may but some assocation with particulate as is definitley the case with reactive silicate and reactive phosphate. For the latter two the definition indicates that this concept, while imperfect in that it may not exactly relate to available nutrient spoecies or concentration for the primary producers, needs to be standadised by flitering to reduce the unknown variability in the association with particulates that could be strip by the reactants in unknown ways and in ways primary producers may effect from their own association or just shifting the equilbrium from particulate to dissolved by the removal of the dissolved fraction. Furthermore if one needs to compare other systems it is imperitive to to have a standadaised protocol to separate methodological differnces from biological and supply differences. I hope thats not too confusing only to reiterate that nutrients concs are not a perfect concept for bioavialbaility and the use must always be in the light that nutrients are not concervative and other than highly eutrophic conditions may not be an indication of supply i.e. most of them may have been used up by the biology or not depending on the growing season.

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3 How to measure concentration of N-15 labelled NH4+ and urea in solution.
By Kasia Piwosz · National Marine Fisheries Research Institute

Kasia Piwosz · National Marine Fisheries Research Institute

Thank you for your answer Tim. I'd expect still other simple organic compounds with N, like aminoacids etc

Thank you for your answer Tim. I'd expect still other simple organic compounds with N, like aminoacids etc

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5 Where can I order vivianite?
By Stefano Romano · Max-Planck-Institut für marine Mikrobiologie

Kenneth Jackson · Lawrence Livermore National Laboratory

I suggest you contact some authors who have recently published papers on vivianite and ask if they have samples they could share with you. It would be... [more]

I suggest you contact some authors who have recently published papers on vivianite and ask if they have samples they could share with you. It would be especially useful to pick someone who has studied properties relevant to the research you intend to do. There are several recent studies in Geochimica et Cosmochimica Acta. You might also look in Economic Geology.

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2 Can you recommend publications about fractionations of sulfur-36 during biological processes?
By Maximilian Halama · Westfälische Wilhelms-Universität Münster

Maximilian Halama · Westfälische Wilhelms-Universität Münster

Thank you for your answer. There are some interesting papers I didn't know yet. But they are all about delta34S values. I am looking particularly for ... [more]

Thank you for your answer. There are some interesting papers I didn't know yet. But they are all about delta34S values. I am looking particularly for publications about delta36S or capdelta36S values.

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12 In-situ sensors to monitor dissolved organic carbon (DOC): UV-vis or fluorescent probes?
By Sébastien Gogo · Université d'Orléans

Piotr Kowalczuk · Institute of Oceanology Polish Academy of Sciences

Dear Leonid, The relationship between DOC and CDOM and DOC and FDOM are strictly local, but them may work also on larger scales, see papers by Rob Sp... [more]

Dear Leonid, The relationship between DOC and CDOM and DOC and FDOM are strictly local, but them may work also on larger scales, see papers by Rob Specer at al on such relationships in USA rivers. The whole problem ls in the specific absorption coefficient and apparent quantum yield of FDOM, which are highly variable and dependent on the composition of CDOM, FDOM and on processes that regulate the compositional transformation. The intensity if such processes is regulated by local conditions. That is why we may establish empirical relationships between DOC and CDOM and DOC and FDOM on local or regional scales, but not on global scale.

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Question:
Open What is the advantage of geochemical normalisation using Aluminium over Average Shale Content or World Rock Surface Average for evaluating sediment quality?
To examine the metal enrichment in sediment compared to background values, indices entailing geochemical normalization using Aluminium, or comparison ... [more]

To examine the metal enrichment in sediment compared to background values, indices entailing geochemical normalization using Aluminium, or comparison to Average Shale content or World Surface has been documented. What are the pros and cons of each method?

By Azubuike Chukwuka · University of Ibadan

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Question:
Open Can anyone tell me how to use MIT Integrated Global Systems Model (IGSM)
I want to learn biogeochemical modelling in marine systems. I am very new to this subject. I came across some papers in this area which used IGSM mode... [more]

I want to learn biogeochemical modelling in marine systems. I am very new to this subject. I came across some papers in this area which used IGSM models and TEM models. I want to learn the basics of framing such models.

By Shiba Acharya · IIT Kharagpur

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7 Diel periodicity in soil redox potential.
By Samuel Pierce · Mississippi State University

C. Hamilton · California State University, Bakersfield

You are quite welcome! I wish you much success in your current research endeavor.

You are quite welcome! I wish you much success in your current research endeavor.

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5 Microbial and chemical oxidation of pyrite in shale: Can both processes be isolated?
By Adeolu Adegbulugbe · University of Leeds

Albert Galy · University of Cambridge

Ian & Johan are theoretically correct but this is only possible if the product(s) of the oxidation are still there, i.e. that some sulfate is still pr... [more]

Ian & Johan are theoretically correct but this is only possible if the product(s) of the oxidation are still there, i.e. that some sulfate is still present in the shale or that you are studying waters seeping out of the shale. If you are left with the shale holding partly dissolved sulfide, this is more difficult and you might want to focus on the trace elements incorporated in the Fe-oxides in order to see whether or not nutrient and nutrient-like elements are depleted.

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Question:
Open Has anyone measured lead (Pb) isotopes in marine organism (mollusks, fish) near or around the African coast recently?
I am interested in doing some comparisons between different geographic regions in the Atlantic.

I am interested in doing some comparisons between different geographic regions in the Atlantic.

By Melania López-Castro · University of Florida

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Question:
Open Relative Soil Improvement Index (RSII) or Soil Degradation Index (SDI) in highly transformed landscapes?
Soil Degradation Index (proposed by Islam and Weil 2000) is widely used to assess relative soil degradation in many publications. The right usage of t... [more]

Soil Degradation Index (proposed by Islam and Weil 2000) is widely used to assess relative soil degradation in many publications. The right usage of this approach depends on if one can find the right "ideal" reference land use type (mostly undisturbed natural forest) in close proximity. However, with the current land use changes occurring in many tropical countries it is less likely to find undisturbed natural forest especially close to other livelihood based land uses. Taking this challenge into account, we came up with "Relative soil improvement index" which rather uses the dominant land use as a reference (e.g. cereal land use in the tropics). The details of the work are shown in the attached article. Any comments, suggestions?

Effects of land use types on soil chemicalproperties in smallholder farmers of central highland Ethiopia. Ekológia (Bratislava) 29(1):1–14. × Lalisa A. Duguma, Herbert Hager, Monika Sieghardt

By Lalisa Duguma · Consultative Group on International Agricultural Research

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2 Biogeochemistry of salt pan deposits
By Santhanakrishnan .T · Bharathidasan University

C. Hamilton · California State University, Bakersfield

Hello! Perhaps these research articles will provide some insight and assistance to you: Isolation of Halobacterium salinarum retrieved directly from... [more]

Hello! Perhaps these research articles will provide some insight and assistance to you: Isolation of Halobacterium salinarum retrieved directly from Halite Brine Inclusions (MORMILE et al., 2003) http://www.ic.ucsc.edu/~saltikov/courses_backup/METX250_files/2003_Mormile_Halite_bacteria.pdf Origins of Halophilic Microorganisms in Ancient Salt Deposits (McGENITY et al., 2000) http://www.blackwellpublishing.com/products/journals/freepdf/emi4.pdf Distribution and Diversity of Halophilic Bacteria in a Subsurface Salt Formation (VREELAND et al., 1998) http://sites.csn.edu/science/Biology/Halophileprotocol.pdf

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1 Can one use Percoll density centrifugation to separate needed cells for the subsequent natural abundance isotope analysis?
By Olga Matantseva · Institute of Cytology of the Russian Academy of Sciences

Markus Lenz · Fachhochschule Nordwestschweiz

you may try to use "sodium polytungstate" density centrifugation instead, this is free of C/N.

you may try to use "sodium polytungstate" density centrifugation instead, this is free of C/N.

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5 In anaerobic soils, when carbon mineralization is enhanced, why isn't phosphate released at a commensurate rate?
By Asher Williams · University of North Florida

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Unfortunately, not related to sulfate-reducers, although I have colleagues that work with thermophillic sufate reduction in ocean vents. Our experienc... [more]

Unfortunately, not related to sulfate-reducers, although I have colleagues that work with thermophillic sufate reduction in ocean vents. Our experience is that the key controls on P-release from soils are intrinsic mineralogy, bacterial abundance and pH. We study carbon-cycling in Arctic soils (among other systems) and we find many major biogeochemical reactions are regulated by "bioavailable" P , pH and the carbonate content of the soil. Therefore, your interpretation makes sense. P is an oddball nutrient because it is scarce and it has difficult chemistry from a biological perspective. However, some microrganisms have come up with a novel way of solving the P problem. I would do a Google search on extracellular phosphatases, which are interesting enzymes some organisms produce that allow most other bacteria bacteria get P. These enzymes seem to trigger P acquisition, which then allow most organisms to hoard P. Good luck in your work. David

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About Biogeochemistry

Biogeochemistry is the scientific discipline that involves the study of the chemical, physical, geological, and biological processes and reactions that govern the composition of the natural environment (including the biosphere, the hydrosphere, the pedosphere, the atmosphere, and the lithosphere).

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