Ground water nitrate concentrations on Nantucket Island, Massachusetts, were analyzed to assess the effects of land use on ground water quality. Exploratory data analysis was applied to historic ground water nitrate concentrations to determine spatial and temporal trends. Maximum likelihood Tobit and logistic regression analyses of explanatory variables that characterize land use within a 1000-...

Natural-abundance delta15N showed that nitrate generated from commercial land application of swine (Sus scrofa domesticus) waste within a North Carolina Coastal Plain catchment was being discharged to surface waters by ground water passing beneath the sprayfields and adjacent riparian buffers. This was significant because intensive swine farms in North Carolina are considered non-discharge oper...

By coupling two commonly used computer programs, MODFLOW (McDonald and Harbaugh, 1988) and MT3Dms (Zheng and Wang, 1998), the SEAWAT program was developed to simulate variable-density, transient ground-water flow in three dimensions. Freshwater head and salt concentration are used as the two principal dependent variables. Major improvements from the previous version of SEAWAT include (1) reform...

We studied two similar riparian sites in southern New England and examined ground water nitrate (NO~--N) removal in the subsurface of mowed (i.e., herbaceous) v . forested (i.e., woody) vegetation. Each site consisted of poorly drained, fine to medium sands and contained adjacent areas of mowed and forested vegetation. We dosed mesocosms with bromide and lSN labeled NO~-N amended ground water t...

One of the most commonly used ground-water remediation technologies is to pump contaminated waterto the surfacefor treatment, Evacuating the effectiveness of pump-and-treat rernediations at Superfund sites is an issue identified by the Regional Superfund Ground Water Forum as a concern of Superfunddecision-makers. The Forum is a group of groundwater scientists, representing EPA’s Regional Super...

Production of adequate supplies of food and fiber currently requires that pesticides be used to limit crop losses caused by insects, pathogens, weeds and other pests. Although pesticides are necessary in today' s agriculture, they can be a serious problem if they reach and contaminate ground water, especially where drinking water needs are met by ground water. The relative reduction of potentia...

Water is a limiting factor for plant growth and vegetation dynamics in alpine sandy land of the Tibetan Plateau, especially with the increasing frequency of extreme precipitation events and drought caused by climate change. Therefore, a relatively stable water source from either deeper soil profiles or ground water is necessary for plant growth. Understanding the water use strategy of dominant ...