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| Compositions and sources of stable organic carbon and nitrogen isotopes in surface sediments of Poyang Lake. |
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Abstract Fifteen surface sediment samples from the Poyang Lake and its main tributaries (Ganjiang River, Fuhe River, Xinjiang River, Xiushui River and Raohe River) were used to investigate organic carbon and nitrogen isotopes. In addition, the sources of organic matter and nitrogen in the surface sediments were analyzed. The total organic carbon (TOC) content in the lake, averages (1.15±0.35)% (n=9) in a range of 0.63% to 1.86%, was higher than that of its main tributaries. The total nitrogen (TN) content in the Poyang Lake area and its main tributaries was in the ranges of 0.06%~0.16% and 0.03%~0.08% with an average value of (0.10±0.03)% (n=9) and (0.06±0.02)% (n=6), respectively. The organic carbon isotope composition (δ13C) ranged from -25.66‰ to -12.56‰ (average (-22.48±4.10)‰), whereas the nitrogen isotope composition (δ15N) was from 3.51‰ to -6.27‰ (average (4.71±0.95)‰) in the Poyang Lake area surface sediments. The δ13C and δ15N values ranged from -25.24‰ to -19.55‰ (average (-23.27±2.42)‰) and 0.94‰ to 4.64‰ (average (3.19±1.30)‰) in the main tributaries surface sediments, respectively. Soil organic matter, aquatic vascular plant and phytoplankton were the main sources of the sediment organic matter in the Poyang Lake and its main tributaries, while the contribution of soil organic matter was biggest. The sources of nitrogen in the sediment were mainly from soil organic matter and synthetic fertilizer. The contribution of synthetic fertilizer was found to be a significant source for the tributaries sediment.
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Received: 20 August 2013
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