鄱阳湖湿地土壤有机碳氮同位素特征及其环境意义

通过对2011年鄱阳湖及其主要入湖河流(赣江、抚河、信江、修水及饶河)15个湿地土壤样品中δ¹³C及δ¹⁵N的测定,分析探讨了鄱阳湖及其主支流湿地土壤有机质和氮素来源.结果表明:鄱阳湖湖区湿地土壤中总有机碳(TOC)的含量在0.45%~1.58%之间,总氮(TN)含量变化范围为0.06%~0.17%;各入湖河流TOC含量为0.41%~1.18%, TN含量在0.05%~0.13%之间.鄱阳湖湖区湿地土壤有机质δ¹³C及δ¹⁵N变化范围分别为-28.35‰~-18.58‰和3.27‰~6.84‰;各入湖河流湿地土壤δ¹³C和δ¹⁵N分别为-25.93‰~-22.66‰和2.97‰~5.41‰.有机质来源分析表明:除湖口处主要来源于C4植物外,鄱阳湖区及其入湖河流湿地土壤有机质的主要来源是C3植物.湖区湿地土壤氮素来源分析表明吴城处主要受农业化肥使用的影响,而其他采样点湿地土壤有机质氮素主要来源于生活污水;入湖河流湿地土壤氮素来源较复杂,生活污水、化肥及工业污水是其主要来源.

Compositions of stable organic carbon and nitrogen isotopes in wetland soil of Poyang Lake and its environmental implications

Fifteen wetland soil samples were collected from the Poyang Lake area and its main tributaries (Ganjiang River, Fuhe River, Xinjiang River, Xiushui River and Raohe River). Contents of carbon and nitrogen isotopes in these samples were quantified to identify the sources of organic matter and nitrogen in the wetland soil. The results showed that the total organic carbon (TOC) and the total nitrogen (TN) contents in the Poyang Lake area were in the ranges of 0.45%~1.58% and 0.06%~0.17%, respectively. The TOC and TN contents in its major tributaries were in the ranges of 0.41%~1.18% and 0.05%~0.13%, respectively. The organic carbon isotope composition (δ¹³C) ranged from -28.35‰ to -18.58‰, while the nitrogen isotope composition (δ¹⁵N) was from 3.27‰ to 6.84‰ in the Poyang Lake area wetland soils. In the main tributaries wetland soils, the δ¹³C and δ¹⁵N values ranged from -25.93‰ to -22.66‰ and 2.97‰ to 5.41‰, respectively. The C3 plants were the main sources of the wetland soil organic matter in Poyang Lake area and its main tributaries; however, C4 plants were the main sources in lake entrances. The sources of nitrogen in the wetland soils were mainly from domestic sewage in the Poyang Lake area, except in Wucheng, which was mainly from synthetic fertilizer there. For the major tributaries, the primary sources of nitrogen included domestic sewage, synthetic fertilizer and industrial sewage.