Abstract：To determine the characteristics of nitrogen contamination and its migration conversion process in Eastern Guilin karst aquifer, 27 samples of ground and surface water were collected during the rainy season and dry season respectively. The results showed that as the main form of inorganic nitrogen, NO3--N of groundwater in Eastern Guilin was highly contaminated. In rainy season, average concentration of NO3--N was 12.5mg/L for the groundwater samples, exceeding groundwater drinking standard line (10mg/L) suggested by the world health organization (WHO). In dry season, the average concentration of NO3--N in groundwater was 8.8mg/L. Although it had a significant decrease, also it still stayed on the verge of the limitation. Only a few surface water samples had high concentration of NH4+ and NO2- due to directly discharged of the sewage, while the concentration of NO3- were low. In this region, δ15N values of nitrates in groundwater ranged from 5‰~25‰, and the values of δ18O ranged from 5‰~10‰, indicating that nitrate source of the groundwater were livestock excrement and living sewage, and also probability of fertilizer and soil organic nitrogen-mixing. At the same time, isotope fractionation generated by microbial nitrification couldn’t be ignored. N and O isotope ratios in part of the sample points were in the range of 1.3~2.1, while another part of the samples were not within this range, indicating that the denitrification was not distinct in the groundwater, and it had spatial heterogeneity.
王开然, 郭芳, 姜光辉, 边红燕. 15N和18O在桂林岩溶水氮污染源示踪中的应用[J]. 中国环境科学, 2014, 34(9): 2223-2230.
WANG Kai-Ran, GUO Fang, JIANG Guang-Hui, BIAN Hong-Yan. Application of 15N and 18O to nitrogen pollution source in karst water in Eastern Guilin. CHINA ENVIRONMENTAL SCIENCECE, 2014, 34(9): 2223-2230.
