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Humic substances marine systems

Dissolved humic substances (DHS) are the main constituents of the dissolved organic carbon (DOC) pool in surface waters (freshwaters and marine waters), groundwaters, and soil porewaters and commonly impart a yellowish-brown color to the water system. Despite the different origins responsible for the main structural characteristics of DHS, they all constitute refractory products of chemical and biological degradation and condensation reactions from plant or animal residues and play a crucial role in many biogeochemical processes. [Pg.151]

Bushaw-Newton, K. L., and M. A. Moran. 1999. Photochemical formation of biologically available nitrogen from dissolved humic substances in coastal marine systems. Aquatic Microbial Ecology 18 285-292. [Pg.260]

In comparing these different environments, one also becomes aware of the tremendous range in environmental conditions (particulate versus dissolved, oxic versus anoxic, etc.) and in the length of time humic substances remain in an environment (hundreds of years in soil or deep aquifers compared to only weeks or months in the surface waters of lakes, streams, and estuaries). One must be equally aware of the fact that, in reality, the lithosphere is not compartmentalized into the convenient categories represented by the various chapters in this section of the book. Rather, each environment is part of an overall system where each overlaps and interacts with neighboring environments. This interaction is dramatized in the case of estuaries where the transition from a freshwater environment to a marine environment is pronounced. [Pg.8]

The metabolism of humic substances is a subject that has received little attention, particularly so for estuarine systems. However, the mass balance calculations of Berner (1982) suggest that a major portion of the terrigenous organic carbon entering the marine environment must be metabolized in some manner the possibility that some fraction of this metabolism occurs in estuaries must therefore be considered. [Pg.230]

Effects of Humic Substances on Plutonium Speciation in Marine Systems... [Pg.382]

X-ray spectra of phosphorus in natural organic molecules. The P NEXAFS spectroscopic studies conducted on isolated humic substances and soil organic molecules indicate that the primary form of P is phosphate and phosphonate (Fig. 24 Myneni and Martinez 1999). When compared to humic substances from soil systems, the fluvial humic substances exhibit phosphonate as one of the important components. However, phosphonate constitutes only a minor fraction of total P in humic substances. Soil samples also exhibit features that correspond to polyphosphate. Another study conducted using NEXAFS spectroscopy at the P absorption edge suggested that marine sediments and humic materials do not exhibit phosphonate and the P NEXAFS spectra of these samples more closely resembled that of hydroxyapatite (Vairavamurthy 1999). [Pg.519]


See other pages where Humic substances marine systems is mentioned: [Pg.156]    [Pg.136]    [Pg.221]    [Pg.858]    [Pg.869]    [Pg.323]    [Pg.232]    [Pg.205]    [Pg.858]    [Pg.869]    [Pg.236]    [Pg.244]    [Pg.245]    [Pg.389]    [Pg.343]    [Pg.120]    [Pg.7003]    [Pg.7014]    [Pg.31]    [Pg.36]   
See also in sourсe #XX -- [ Pg.382 , Pg.383 , Pg.384 , Pg.385 , Pg.386 ]




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Humic substances

Marine systems

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