Land use in the Connecticut River basin, USA: combining GIS and stable isotopes

Stable isotopes of nitrogen have been successfully employed to quantify the extent of non-point source nitrogen contamination in natural waters (Ostrem et al., 1998). Major nitrate sources include atmospheric deposition, fertilizers, animal waste and nitrification of soils and snow. Variations in delta(15)N have been successful in defining these sources in waters (Kendall, 1998). GIS techniques were combined with nitrate concentrations and hydrogen and nitrogen isotopic ratios of river waters to investigate the effect of land use on the water chemistry of the Connecticut River basin in northeastern USA. The results suggest urban development in the southern portion of the basin increases runoff rates and decreases soil residence times.