摘要 : We used the isotopic composition of nitrogen ( delta 15N) and oxygen ( delta 18O) in water nitrate (NO3-) to assess water pollution. Water samples were taken in the catchment area of the brook Zarnow, 15 km southeast of the city o... 展开 We used the isotopic composition of nitrogen ( delta 15N) and oxygen ( delta 18O) in water nitrate (NO3-) to assess water pollution. Water samples were taken in the catchment area of the brook Zarnow, 15 km southeast of the city of Rostock (Germany). delta 15N and delta 18O values in drainage water nitrate of a conventionally managed field and the adjacent surface waters were measured for 6 weeks during the main discharge period of the hydrological year 2003/2004. We hypothesized that this approach could provide more information about the impact of drainage water containing high nitrate loads on the following surface water bodies than common measurements of concentrations. The nitrate concentrations ranged between 686 and 2040 micro M in the tile drain outlets and were positively correlated to the tile drain discharge. The low delta 18O-NO3- values, from 1.8 to 4.3 per mil, indicated that most of the nitrate was derived from the nitrification process in the agricultural soils. The high delta 15N-NO3- values, from 8.5 to 15.0 per mil, reflected the long-term fertilizer application, which was carried out for several years with inorganic as well as organic fertilizers. In the adjacent ditch and brook, nitrate concentrations were lower but showed a similar development to the tile drain outlet. The delta 15N-NO3- values (7.2-12.1 per mil) and delta 18O-NO3- values (2.4-9.1 per mil) in the ditch and the brook indicated that the nitrate from tile drain discharge is the major N source for the adjacent surface water bodies.. 收起