鄱阳湖三江口柱状沉积物有机氮同位素特征及其环境指示意义

通过对鄱阳湖三江口处柱状沉积物中δ15N、C/N比值、TOC和TN等含量的测定,分析了其有机质及氮素的来源.结果表明: 赣江、抚河、信江及鄱阳湖处柱状沉积物δ15N值变化范围分别为2.44‰~4.55‰、4.03‰~5.84‰、3.79‰~4.81‰及3.42‰~8.13‰.赣江南支其沉积有机质主要来源于土壤有机质;抚河整个柱状沉积物以自生有机物源为主;信江西支在12cm以下其沉积有机质主要受藻类及土壤有机质两种物源的影响,而12cm以上受外源影响比较小;鄱阳湖梅溪嘴表层2cm处沉积有机质来源以藻类为主,而中间6~3cm处主要来源于土壤有机质,7cm以下主要来源于藻类及土壤有机质.赣江南支、信江西支及鄱阳湖梅溪嘴沉积物氮素均主要来源人工合成肥料和土壤流失氮,而抚河主要来源于土壤流失氮.

Stable organic nitrogen isotope in core sediments of the Three Rivers Estuary,Poyang Lake and its environmental implications

Samples of core sediments from the Three Rivers Estuary of Poyang Lake (Ganjiang River south branch, Fuhe River, Xinjiang River west branch and Poyang Lake) were collected. The compositions of stable nitrogen isotope (δ15N), C/N ratio, total organic carbon (TOC) and total nitrogen (TN) in these samples were determined for investigating the origin of sedimentary organic matter and nitrogen. The results showed that δ15N ranged from 2.44‰ to 4.55‰, 4.03‰ to 5.84‰, 3.79‰ to 4.81‰ and 3.42‰ to 8.13‰ in the sediment for the Ganjiang River south branch, Fuhe River, Xinjiang River west branch and Poyang Lake, respectively. The sedimentary organic matter was mainly from the soil organic matter in Ganjiang River. The sources of sedimentary organic matter were generally autochthonous in Fuhe River. The sources were mainly from the algae and the soil organic matter below 12cm, and autochthonous up 12cm in the sedimentary organic matter of Xinjiang River. In Poyang Lake, the sedimentary organic matter was autochthonous in the surface layer; the contribution of soil organic matter was obvious from 6cm to 3cm; the algae and the soil organic matter were the main sources of the sedimentary organic matter below 7cm. Chemical fertilizer and soil erosion were the main sources of nitrogen in sediments for Ganjiang River, Xinjiang River and Poyang Lake. The sources of nitrogen in the sediment were mainly from the soil erosion for Fuhe River.