Abstract:To discriminate among NO3-–N sources in different water bodies in paddy rice system, δ15N-NO3- abundance and chemical compositions (e.g., NO3-, NH4+, TP, Cl-, SO42-) were measured in water samples from pond, irrigation ditch, river, and ground water in rice system of the Taihu Lake region at three periods. It was found that nitrate was the dominant nitrogen species in most water samples. During the fertilizing period (June), the δ15N-NO3- value of water samples were lower than those collected in other months, suggesting that the surface water and groundwater receive a significant contribution of NO3-–N from agricultural fertilizer at this period. In periods prior to fertilization (April to May), the low δ15N value in pond water was attributed to rainfall, and the high δ15N value in ground water resulted mainly from denitrification. In periods after the fertilization (July to August), the high δ15N value in pond water was caused by aquaculture wastewater, and the low δ15N value in ground water indicated main nitrate source of agricultural leaching. The δ15N values varied within a narrow range in river and irrigation water during all the three periods, but their nitrate source differed. Sewage and manure contributed nitrate to river water, while rainfall mainly control the nitrate of irrigation water. We put forward new intervals of Cl- and molar ratio of NO3-/Cl- to discriminate among NO3-–N sources in Taihu Lake region.
夏永秋, 李跃飞, 张心昱, 林静慧, 王书伟, 周伟, 颜晓元. 太湖地区稻作系统不同水体硝态氮同位素特征及污染源[J]. 中国环境科学, 2014, 34(2): 505-510.
XIA Yong-Qiu, LI Yue-Fei, ZHANG Xin-Yu, LIN Jing-Hui, WANG Shu-Wei, ZHOU Wei, YAN Xiao-Yuan. Nitrogen isotopic characteristics and source attribution of nitrate in different water bodies in the paddy rice system of the Taihu Lake region. CHINA ENVIRONMENTAL SCIENCECE, 2014, 34(2): 505-510.