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11.
Frank N. Bruscato Assistant Professor J. Roger McHenry Research Chemist 《Journal of Hydrology》1970,10(4):406-417
A series of Co-60 compounds, considered as potentially useful tracers of groundwater movement, were prepared and evaluated in soil column and batch studies. The compounds were: potassium hexacyanocobaltate (III), K3Co(CN)6; potassium ethylenediamminetetraacetato-cobaltate (III), KCo(EDTA); ammonium 12-tungstodicobaltoate (III), (NH4)8[Co(II)Co(II)W12O42] · 20 H2O; chloraquotetrammine cobalt (III) chloride, [Co(NH3)4(H2O)Cl]Cl2; and sodium hexanitrocobaltate (III), Na3Co(NO2)6. The performance of K3 60Co(CN)6 and K 60Co EDTA were dependent on their environment and more especially on the type and amount of clay present. The EDTA cobalt complex cannot be used in soils that are basic or where a large fraction of the clay is saturated with Na+ and/or Ca++. Of the other radioactive tracers tested, none were suitable for groundwater tracing because of instability in aqueous solution (Na3Co(NO2)6), variable anionic structure under acid conditions ((NH3)8[Co(II)Co(II)W12O42] · 20 H2O), or preferential uptake by the clay fraction ([Co(NH3)4(H2O)Cl]Cl2). 相似文献
12.
Recent sediment accumulation rates were measured in Moon Lake, a large (10.1 km2) Mississippi River oxbow lake in northwestern Mississippi. Moon Lake, which receives channeled inflow from an intensively cultivated soybean, rice, and cotton watershed (166 km2) and limited overland flow from surrounding lands, exhibited depositional patterns that were associated with (1) points of inflow, (2) flow patterns, and (3) lake morphology. From 1954 to 1965, 70 percent of the lake bottom experienced accumulation rates greater than 2 cm/yr. Accumulation rates exceeded 4 cm/yr in areas of delta formation. Changes in cropping systems during the 1960s, from cotton to soybeans and rice which require less cultivation, resulted in significantly (a = 0.01) less sediment accumulation during the period 1965- 1982 when 86 percent of the lake averaged less than 2 cm/yr sediment deposition. If current sediment accumulation rates continue, open water habitat in the lake will be reduced by only 3 to 7 percent during the next 50 years.Contribution of the Sedimentation Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Oxford, MS 38655 相似文献