Comparison of Methods for Sampling Dissolved Nitrogen in a Fractured Carbonate-Rock Aquifer |
| |
| Authors: | Patricia L Lietman James M Gerhart Kim L Wetzel |
| |
| Institution: | Patricia L. Lietman received her B.S. in chemistry from Indiana University of Pennsylvania in 1971. She worked as a water chemist for the U.S. Geological Survey from 1971 to 1973, and as a food and feed chemist for Ralston Purina Co. from 1974 to 1976. In 1977, she returned to the U.S. Geological Survey (P.O. Box 1107, Harrisburg, PA 17108), first as a hydrologic technician in the sediment laboratory, then as a hydrologist. Her hydrology studies have concentrated on agricultural non-point-source investigations of surface and ground water. She is currently project chief of the Conestoga Headwaters Project in the Pennsylvania subdistrict office.;James M. Gerhart received his B.A. in geology from Franklin and Marshall College in 1973, and his M.S. in geology from Pennsylvania State University in 1977. He began working as a hydrologist with the U.S. Geological Survey in Florida in 1977, transferred to Pennsylvania in 1979, and transferred to Maryland (208 Carroll Building, 8600 LaSalle Rd., Towson, MD 21204) in 1984. He has worked on a variety of projects for the U.S. Geological Survey, with particular emphasis on ground water flow modeling and non-point-source pollution. He currently is responsible for the management of hydrologic studies in the Maryland office.;Kim L. Wetzel received her B.S. in mathematics from Pennsylvania State University in 1975. She began working as a hydrologist with the U.S. Geological Survey, Pennsylvania District (P.O. Box 1107, Harrisburg, PA 17108) in 1975. She has worked on a variety of projects involving estimation techniques, sedimentation, and data management. |
| |
| Abstract: | As part of an agricultural non-point-source study in the Conestoga River head waters area in Pennsylvania, different methods for collecting ground water samples from a fractured carbonate-rock aquifer were compared. Samples were collected from seven wells that had been cased to bedrock and drilled as open holes to the first significant water-bearing zone. All samples were analyzed for specific conductance, dissolved oxygen, and dissolved-nitrogen species. Water samples collected by a point sampler without pumping the well were compared to samples collected by a submersible pump and by a point sampler after pumping the well. Samples collected by using a point sampler, adjacent to major water-bearing zones in an open borehole without pumping the well, were not statistically different from samples collected from the pump discharge or from point samples collected adjacent to major water-bearing zones after pumping the well. Samples collected by using a point sampler without pumping the well at depths other than those adjacent to the water-bearing zones did not give the same results as the other methods, especially when the water samples were collected from within the well casings. It was concluded that, for the wells at this site, sampling adjacent to major water-bearing zones by using a point sampler without pumping the well provides samples that are as representative of aquifer conditions as samples collected from the pump discharge after reaching constant temperature and specific conductance, and by using a point sampler after pumping the well. |
| |
| Keywords: | |
|
|
