洞庭湖表层沉积物营养盐污染特征与评价

Pollution Characteristics and Evaluation of Surface Sediment Nutrients in Dongting Lake

  • 摘要: 为揭示洞庭湖表层沉积物营养盐的空间分布特征和污染状况,于2012年2月和2013年4月采集了该湖具有代表性的9个点位的表层沉积物,测定了其有机质(OM)、总氮(TN)和总磷(TP)浓度。结果表明,OM浓度为1.48%~4.22%,平均值为2.06%;TN浓度为382~2 217 mg/kg,平均值为1 340 mg/kg;TP浓度为142~716 mg/kg,平均值为294 mg/kg。与国内其他湖泊(水库)相比,洞庭湖表层沉积物中OM和TN浓度处于中等水平,其内源负荷不容忽视;OM和TN浓度的空间分布相似,总体表现为南洞庭湖区>东洞庭湖区>西洞庭湖区。TP浓度总体表现为东洞庭湖区>西洞庭湖区>南洞庭湖区。C/N为6.1~14.8,平均值为10.2。从生物沉积角度而言,洞庭湖表层沉积物OM主要来源于浮游动物与浮游植物。有机指数和有机氮评价结果显示,洞庭湖湖体沉积物环境状况较好,整体处于较清洁至尚清洁范畴。

     

    Abstract: In order to explore the spatial distribution characteristics and pollution status of surface sediment nutrients in Dongting Lake, sediment samples at nine representative sampling stations were collected in February of 2012 and April of 2013, and contents of organic matter(OM), total nitrogen(TN) and total phosphorus(TP) in the sediments of each station were measured. The results show that the contents of OM are 1.48%-4.22% with the average value of 2.06%, the contents of TN are 382-2 217 mg/kg with the average value of 1 340 mg/kg, and the contents of TP are 142-716 mg/kg with the average value of 294 mg/kg. Compare with other lakes or reservoirs in China, the contents of OM and TN in Dongting Lake are in the middle level, its endogenous load should not be ignored. The spatial distribution of OM content is similar to that of TN, generally in the order of South Dongting Lake >East Dongting Lake> West Dongting Lake, while TP content is generally in the order of East Dongting Lake > West Dongting Lake > South Dongting Lake. The C/N ratios are 6.1-14.8 with the average value of 10.2. From the point of biological deposition, the OM in surface sediments of Dongting Lake predominantly originates from zooplankton and phytoplankton. Organic index and organic nitrogen assessment results show that Dongting Lake sediment environment is relatively good, overall in clean to just clean category.

     

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