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Chemistry and occurrence of cadmium and zinc in surface water and groundwater
Author(s) -
Hem John D.
Publication year - 1972
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr008i003p00661
Subject(s) - cadmium , zinc , solubility , saturation (graph theory) , environmental chemistry , carbonate , chemistry , groundwater , sorption , seawater , surface water , zinc hydroxide , hydroxide , solubility equilibrium , mineralogy , inorganic chemistry , environmental science , geology , environmental engineering , adsorption , geotechnical engineering , organic chemistry , oceanography , mathematics , combinatorics
The median concentration of zinc in 726 filtered samples of water taken from rivers and lakes of the United States in November 1971 was close to 20 μg/l, and the median concentration of cadmium was a little below 1 μg/l. The concentrations of both elements tended to be consistently higher in water from northeastern and southeastern states. Chemical thermodynamic calculations summarized by solubility graphs suggest that the carbonate and hydroxide solubilities of these elements are higher than the concentrations commonly found, but for 24 of 80 analyses for which chemical equilibrium computations could be made, saturation with respect to one or both of the metals was closely approached. Zinc solubility may also be controlled by silicate in some waters. Biological factors and Sorption by stream sediments may also be significant controls. Concentrations of cadmium above 10 μg/l may be stable in water having low total solute concentrations and p H and can be difficult to remove by conventional water treatment processes.