ISSN:
1432-1009
Keywords:
Groundwater quality
;
Nitrate
;
Well depth
;
Public and non-public wells
;
Agricultural environments
;
Monitoring programs
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract Groundwater quality in Iowa varies with depth, location, ownership of well, time of sampling, and geologic features. Samples from deep wells (〉30.48 m or 100 ft) are highly mineralized with sulfates and carbonates (calcium and magnesium), whereas the mineral content in samples from shallow wells (〈30.48 m or 100 ft) is relatively much lower. Nitrate as a percent of dissolved solids is negligible in samples from deep wells and reaches as high as 3 to 5% in samples from shallow wells. Shallow wells, in particular non-public wells, are highly susceptible to nitrate contamination (with an average concentration of 27.8 mg/l) compared with any other category of wells studied. In shallow non-public wells, the concentration of nitrate from recent geologic deposits (31.61 mg/l) is more than twice the level found in corresponding public wells from similar deposits (13.35 mg/l). Shallow non-public wells are also subject to sharp seasonal fluctuations, with a peak nitrate concentration of 55.81 mg/l in the month of May, possibly because of spring runoff from agricultural and other surface sources. These observations are further supported by the results of nitrate analyses from a large number (over 44,000) of private wells in Iowa. Eighteen percent of these private wells were found to exceed the maximum contaminant level of 45 mg/l nitrate (NO3 −). A higher proportion of the shallow wells (〈30.48 m or 100 ft) exceed the maximum contaminant level of 45 mg/l (3867 out of 13,625 or 28.4%). It is proposed that the observed variability in groundwater quality be used as a first step in developing a strategy for strengthening state-wide groundwater quality monitoring programs. Strong state-wide programs would be of considerable assistance to policy makers in the resolution of major groundwater quality issues.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01867126
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