江苏省淮安市典型湿地底泥营养盐分布特征及污染评价

江苏淮安具有丰富的湿地资源。文章基于区内典型湿地底泥调查结果,开展营养盐含量特征及污染评价研究。结果表明:湿地底泥总氮、总磷、有机质含量分别为0.26~6.51 g/kg、0.36~3.98 g/kg、0.52％~10.17％,具有较大变异性;总体来看,公园池塘、湖泊底泥的营养盐含量最高,沟渠、水产养殖场底泥中营养盐含量次之,河流水系沉积物中营养盐含量最低。湿地底泥有机碳、总氮、总磷含量之间均呈显著正相关,反映它们的来源、迁移转换过程具有一定的相似性。其中,湖泊底泥C/N平均值(8.6)较小,有机物主要来源于湖泊内水生藻类植物;公园池塘、河流、沟渠、水产养殖场底泥具有较大的C/N平均值(9.9~11.9),有机物来源主要受陆源物质影响。底泥中有机氮、有机指数和污染指数的评价结果显示,研究区底泥受到不同程度的污染,成因与区内畜禽养殖、农田施肥等农业活动密切相关。建议推进研究区畜禽养殖污染和粪污资源化利用,实施科学施肥,减少化肥使用量。

Distribution characteristics and pollution evaluation of nutrient salts in typical wetland sediment in Huai'an,Jiangsu Province

There is abundant wetland resource in Huai'an, Jiangsu Province. The distribution characteristics and pollution evaluation of nutrient salts in typical wetland sediment in the study area have been analyzed, and the results show that the concentration of total nitrogen, total phosphorus, and organic matter has wide range between 0.26~6.51 g/kg, 0.36~3.98 g/kg, 0.52％~10.17％ respectively, indicating great spatial variability of the nutrient salts. Overall, park ponds and lakes have the highest contents of nutrient salts, followed by ditches and aquaculture farms, and rivers have the lowest contents of nutrient salts. There are significant positive correlations among the contents of organic matter, total nitrogen, and total phosphorus in wetland sediment, which implies a certain similarity in their sources, migration and transformation processes. The lake sediments have relatively lower ratios of C/N (8.6) and their organic matters mainly sourced from aquatic algae and plants. However, sediments in park ponds, rivers, ditches and aquaculture farms have much higher mean ratios of C/N (9.9~11.9) and their organic matters are mainly affected by terrestrial materials in origin. The evaluation results of organic nitrogen, organic index, and pollution index on nutrient salts in sediments are relatively consistent, which implies that the wetland sediment in the study area have been polluted to some extent, closely associated with the local agricultural activities such as livestock and poultry breeding and farmland fertilization. It is suggested to promote resource utilization by transforming the waste of livestock and poultry breeding into fertilizers, so as to implement scientific fertilization and reduce the usage of chemical fertilizers in the study area.