I am working on labile soil carbon fractions where I came across with these two term water soluble and dissolved organic carbon. When I was searching protocol for both the water soluble and dissolved organic carbon I found different protocols where the main extractant is either distilled/de-ionized water, 0.01 M CaCl2 or 2 M KCl. So, my question is whether both of these fractions are synonymous or represent the similar labile fractions of soil carbon? It will be highly helpful for any guidance as well as if any one can share protocol on dissolved organic carbon in soil. Thanks in advance for any help.
Regards
Sudeshna
Dear Sudeshna Bhattacharjya ,
various methods has been used to measure organic carbon dissolved in solutions. You can extract dissolveable organic carbon (DOC) by using salt solutions (e.g. 0.01 M CaCl2) to simulate ionic strength of natural soil solutions. Using pure water to extract dissolveable carbon is a measure for water extractable organic carbon (WEOC). Thus, in laboratory you can measure DOC by using salt solutions and WEOC by using pure water. In field you are able to collect soil solutions (e.g. lysimeter) to assess DOC. See also following publications:
Article Dissolved and Water-Extractable Organic Matter in Soils: A r...
Article Filtration increases the correlation between water extractab...
Best regards
Nils
When water originates from land areas with a high proportion of organic soils, these components can drain into rivers and lakes as dissolved organic carbon. Dissolve organic carbon is also extremely important in the transport of metals in aquatic systems. My researchers use the term ' dissolved ' for compound below 0.45 micrometers but 0.22 micrometers is also common, saving colloidal for higher concentrations.
Bulk dissolved and particulate organic carbon concentrations are usually analyzed by conversion to CO2 followed by analysis of concentration of this gas. Some controversy exists regarding the effeciency of different methods ( UV, high temperature, or persulfate oxidation digestions) used to decompose organic carbon to CO2. For more details consult Freshwater Ecology ( Second Edition ), 2010
When one looks at the terms organic dissolved carbon this is compound which is transported in water as a solute. Like organic matter is it an operational definition based on capture of mixtures of carbon based materials. Materials which dissolve in water can have get chemical reactivity compared to insoluble materials. Much of the enthusiasm for compost teas is based on the high activity of small amounts of material in solution. From an economic and logistical aspect having ability to get high acitivity for trace material amounts is highly attractive. Water soluble carbon and dissolved organic carbon are nearly synonymous if not synonyms. Carbonate would be an example of inorganic carbon which many researchers like to separate out from the organic forms. In alkaline conditions as in soils a significant portion of the total carbon can be inorganic carbonate rather than organic carbon forms.
Dear Sudeshna Bhattacharjya ,
various methods has been used to measure organic carbon dissolved in solutions. You can extract dissolveable organic carbon (DOC) by using salt solutions (e.g. 0.01 M CaCl2) to simulate ionic strength of natural soil solutions. Using pure water to extract dissolveable carbon is a measure for water extractable organic carbon (WEOC). Thus, in laboratory you can measure DOC by using salt solutions and WEOC by using pure water. In field you are able to collect soil solutions (e.g. lysimeter) to assess DOC. See also following publications:
Article Dissolved and Water-Extractable Organic Matter in Soils: A r...
Article Filtration increases the correlation between water extractab...
Best regards
Nils
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https://www.sciencedirect.com/topics/earth-and-planetary-sciences/dissolved-organic-carbon
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