Mississippi River dissolved loads

Figure 9.9 Mean annual N load for the Mississippi River at Belle Chase, LA (1979—1981), hy N form, including total nitrogen (closed triangles), dissolved inorganic nitrogen (open circles), dissolved organic nitrogen (closed circles), and particulate nitrogen (open triangles) (Alexander...

Figure 10.18. Effect of pH on residual metal concentration in fresh waters. Dissolved zinc is plotted against pH. (a) Zinc in relatively undisturbed major rivers including the Yangtze (Chiang Jiang) and tributaries of the Amazon and Orinoco, (b) Zinc normalized to total dissolved solids for the same set of major rivers, (c) Zinc in pH-adjusted aliquots of Mississippi River water (April 1984, 103 mg liter suspended load, pH 7.7) the adjusted aliquots were allowed to equilibrate overnight before filtration and analysis. (From Shiller and Boyle, 1985.) (d) Zinc in different mountain lakes in the southern parts of the Swiss Alps. These lakes are less than 10 km apait, so that the atmospheric inputs can be considered to be uniform over this scale, but their water composition (pH) is influenced by different bedrocks in their catchments. A similar dependence on pH has also been observed for Cd and Pb but this dependence is less pronounced with Cu(II) when solute complex formation counteracts adsorption (data 1983-1992). (From Sigg et al., 1995, in press.)...

Laboratory studies have shown that sediments accumulated (332 ixg kg ) hexachlorobenzene from water (8.3 )ug L ) with a concentration factor of 40 (Laseter et al., 1976). Depuration was relatively long, exceeding that of the biota. Laska etal. (1976) showed that the concentration of hexachlorobenzene in the vicinity of an industrialized zone bordering the Mississippi River between Baton Rouge and New Orleans was 80 times greater in the soil adjacent to the river than in the water. This was due to the suspended and dissolved load in the river water. No specifrc environmental sorption data are available on other monocyclic aromatic compounds. 

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