Organic matter groundwaters

Reduced iron (Fe(II)) and sulfide present in water can precipitate or coprecipitate to form pyrite (FeS2) or other sulfide minerals, often in the presence of organic matter. Groundwater may be enriched in Fe(II) by... 

The chemical composition of the soil and groundwater, specifically the amount of natural organic matter (NOM) and other reduced species, such as iron (II) or manganese (II) often analyzed as the chemical oxygen demand (COD) of the soil, or the soil oxidant demand. 

Mechanical intrusion is the penetration of the matter to be dated by carbon of a different age from that of the sample itself if not taken into account, mechanical intrusion, too, leads to erroneous ages. The penetration of rootlets from growing plants into buried specimens, the infiltration of windblown organic matter, and the accidental insertion of fibers from brushes or other instruments used to clean a sample are examples of likely modern carbon intrusions into prospective samples, which lead to assigning to a sample later dates than the true ones old carbon intrusions, such as those caused by the penetration of carbonate minerals from groundwater, or of petrol or oil from excavating tools, on the other hand, are conducive to assigning earlier dates than the true ones. 

KoC is an important parameter which describes the potential for movement or mobility of pesticides in soil, sediment and groundwater. Because of the structural complexity of these agrochemical molecules, the above simple relationship which considers only the chemical s hydrophobicity may fail for polar and ionic compounds. The effects of pH, soil properties, mineral surfaces and other factors influencing sorption become important. Other quantities, KD (sorption partition coefficient to the whole soil on a dry weight basis) and KqM (organic matter-water partition coefficient) are also commonly used to describe the extent of sorption. K0M is often estimated as 0.56 KoC, implying that organic matter is 56% carbon. 

Khan AT, Thomson MB (1990) Groundwater transport of hydrophobic organic compounds in the presence of dissolved organic matter. Environ Toxicol Chem 9 253-263... 

Nitrogen 15n/14n 14N = 99.633 15N = 0.366 Organic matter, soil, dissolved N03 and NH4+, groundwater Diet, nitrogen fixation pathways, animal water use, climate, groundwater pollution... 

Given these two main factors (i.e., oxygen availability and organic matter content), several generalizations can be made about solid phase surfaces, the vadose zone, and the groundwater region as follows ... 

Recently, Burkhard (2000) reviewed contaminant sorption by dissolved organic matter. Using several hundreds of UCC-water partition coefficients (A doc) reported in these studies, he found that UCC-water partition coefficients for naturally occurring DOC (humic and fulvic acids, sediment pore water, soil pore water, groundwater, and surface water) was best described by... 

Lafrance, P., Marineau, L., Perreault, L., and Villenueve, J.-P. Effect of natural dissolved organic matter found in groundwater on soil adsorption and transport of pentachlorophenol. Environ. Sci. TechnoL, 28(13) 2314-2320, 1994. 

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