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Geology topics

J. A. Leenheer

Publications and source records attributed to J. A. Leenheer.

4 recordsLinked to original sources

Chemistry of dissolved organic matter in rivers, lakes, and reservoirs

Recent investigations provide new insight on the structural chemistry of dissolved organic matter (DOM) in freshwater environments and the role of these structures in contaminant binding. Molecular models of DOM derived from allochthonous and autochthonous sources show that short-chain, branched, and alicyclic structures are terminated by carboxyl or methyl groups in DOM from both sources. Allochthonous DOM, however, had aromatic structures indicative of tannin and lignin residues, whereas the autochthonous DOM was characterized by aliphatic alicyclic structures indicative of lipid hydrocarbons as the source. DOM isolated from different morphoclimatic regions had minor structural differences.

Book chapter

Occurrence of dissolved organic carbon in selected ground-water samples in the United States

A study of nonvolatile DOC (dissolved organic carbon) in ground water was conducted to establish base levels of naturally occurring dissolved organic materials. Samples of ground water were obtained at 100 sites in 27 States. Samples were pressure filtered at the time of collection and immediately frozen on dry ice. DOC concentrations were determined by wet oxidation of organic carbon to carbon dioxide which was measured by an infrared analyzer. The DOC concentrations ranged from less than the 0.1 mg/l limit of detection to 15 mg/l. Concentrations of DOC were directly correlated with specific conductance and alkalinity, but did not correlate with pH. The DOC mean concentration was 1.2 mg/l; however, the DOC median value was lower at 0.7 mg/l. Differences in DOC concentration for various types of consolidated rock aquifers were slight; for example, median DOC values for sandstone, limestone, and crystalline rock aquifer types ranged from 0.5 to 0.7 mg/l. No difference was found in the median DOC concentration between shallow (<200 ft; 61 m) and deep (>200 ft) sand and gravel aquifers.

Journal of Research of the U.S. Geological Survey