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Muldoon, Maureen A.; Madison, Frederick William, 1937-; Lowery, Birl / Variability of nitrate loading and determination of monitoring frequency for a shallow sandy aquifer, Arena, Wisconsin
[DNR-123] (1998)

Results and discussion,   pp. 9-20 PDF (3.1 MB)

Page 9

        An ISCO automated sampler, powered by a 12-volt marine battery, was installed to
 collect samples from piezometer 1. Two sample collection schemes were used during the project.
 From the initiation of sampling until June 15, 1997, samples were collected every three hours and
 four samples were composited into a single bottle. From July 1, 1997 until the end of the project,
 samples were collected at 12-hour intervals during the growing season. A float device was used
 to keep the intake tubing six inches below the top of the water column in piezometer 1. The
 sampler automatically reversed the pump and purged the sample line after collection of each
 sample. Samples were retrieved at 2-week intervals and taken to the UW Soil and Plant Analysis
 Lab for nitrate and chloride analysis by ion chromatography. All sampling results are included in
 the Appendix.
                               RESULTS AND DISCUSSION
The primary objective of this project was to determine the temporal variability of nitrate loading
to the water table in shallow, sandy aquifers. Data from the 1997 provide a relatively complete
record of nitrate movement from March to December. These results are discussed in detail
below. Results from 1996 and 1998 are less complete and are discussed only briefly. Figures 4,
5, and 9 summarize the water-quality, depth-to-groundwater, and precipitation data for 1996,
1997, and 1998 respectively. For each of these graphs, the major tick marks on the date axcis are
spaced every 28 days with minor tick marks every week (7 days).

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