ANYL 325 |
| Peter Ravenscroft and John M McArthur. |
| In Bangladesh, concentrations of boron in groundwater reach 2.1 mg/L and are high regionally in alluvial aquifers of Late Pleistocene/Holocene age. In Ingham County, Michigan, concentrations reach 6.1 mg l/L and high values are widespread in the north east of the county. These concentrations exceed the regulatory guideline values for human consumption of 0.5 mg l/L (WHO) or 0.9 mg l/L (USA). The boron has desorbed from mineral surfaces as freshwater flushing displaces saline waters from the aquifers. Desorption is driven by decreasing ionic strength, the equilibrium re-adjustment of mineral sorption sites to the low boron concentration in freshwater, and competitive exchange with bicarbonate/carbonate. Boron enrichment is accompanied by ion-exchange that depletes calcium and enriches sodium in the flushing freshwater. The patterns of enrichment and depletion indicate the direction of water quality change, in terms of salinization or freshening, with greater sensitivity than absolute chemical parameters, and so provides a sensitive test to descriminate between them that will be of value in water-resource development. |
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Assuring Water Purity
8:30 AM-12:00 PM, Wednesday, 29 March 2006 Georgia World Congress Center -- B214, Oral
Division of Analytical Chemistry |