HUANG Qiang-sheng1,2, LI Qing-guang2, LU Wei-qi1,2 ,YANG Wei-hong3, WANG Shi-lu1
(1. The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. University of Chinese Academy of Sciences, Beijing 100039, China; 3.The Ministry of Land and Resource of the Central Geological Prospecting Fun Management Center)
Abstract: To assess nitrate pollution and identify its potential sources, groundwater and river water were sampled in the Dianchi Lake Basin, China. Water chemistry and nitrogen isotopes were determined for the samples. The results showed the concentrations of NO3- in the groundwater and river water range from 0.05 to 99.52 mg/L and from 0.01 to 45.92 mg/L, respectively. The high NO3- concentrations often occur in the residential area (41.41±39.32 mg/L, n=8) and Kunming City (19.91±15.02 mg/L，n=24), and the low NO3- concentrations appear in the spring water in woodland spring and in the upstream water of the Panlongjiang River, as well as in the streams in the southern and eastern areas of the watershed. The nitrogen isotopic compositions showed that NO3- in the groundwater in residential areas （+9.9‰～+27.8‰） and in the river water in Kunming City (+3.2‰～+32.1‰) originates mainly from domestic sewage. NO3- pollution in the river water in the southern and eastern parts of the drainage basin is derived from chemical fertilizers. The low δ15N-NO3- values (+10‰) occurring in the woodland spring and upstream water of the Panlongjiang River indicated that atmospheric deposit is the main source of anthropogenic N. With a large range of δ15N-NO3- values (+5.5‰～+23.7‰) and higher concentrations of nitrate (45.77±40.91 mg/L), nitrate in groundwater in the cultivated land is mainly derived from human and animal wastes, chemical fertilizers and atmospheric deposits.
Key words：Dianchi Lake Basin; nitrate; hydrochemistry; nitrogen isotope
EARTH AND ENVIRONMENT Vol. 42, No.5, Tot No.301, 2014, Page 589-596
