CHEN Jiji¹, XU Sushi¹, ZHAO Liang¹, GUO Jing¹, TAO Lei¹, JING Hongwei¹

(Beijing municipal environmental monitoring center, Beijing 100048, China)

Abstract: In order to control the water pollution and assure the safety of surface drinking water, the sources of suspended particulate organic matter (POM) in Miyun reservoir watershed (Beijing) in summer were studied by analyzing the concentration of POM and the stable carbon and nitrogen isotopes in surface waters in summer. In addition, the water from Jingmi diversion canal was studied as the reference. Results showed that the content of particulate organic carbon in Miyun reservoir watershed varied from 0.04 to 0.71 mg/L, with an average value of 0.26 mg/L; the content of particulate organic nitrogen in Miyun reservoir watershed varied from 0.01 to 0.24 mg/L, with an average value of 0.07 mg/L; POM concentration in the reservoir was higher than the tributary rivers, but all were generally lower than other rivers and lakes at home and abroad. POM in the study area in summer was mainly from the endogenous substances. Soil erosion contributes more POM to tributaries than to reservoir; moreover, the contribution of exogenous input (including domestic source, soil erosion, etc.) in Chao River was higher than that in Bai River. Concentrations of particulate organic carbon in Miyun reservoir watershed were significantly lower than that in Jingmi diversion canal (P<0.01), and there might be differences in carbon concentration and composition between these two waters. In general, POM concentration in Miyun reservoir watershed was low in summer and mainly came from the endogenous substances.

Key words: particulate organic matter (POM); carbon and nitrogen isotope; carbon-nitrogen ratio; water from Miyun reservoir watershed

EARTH AND ENVIRONMENT Vol.49, No.2, Tot No.340, 2021, Page 157-163