河流岸带湿地沉积物重金属分布对植被物种多样性和底栖动物群落特征的影响

河流岸带湿地栖息地完整性对河流水环境、水生态和水文的安全与健康具有重要意义，为探究河流岸带湿地表层沉积物重金属分布特征及其对植被和底栖动物的影响，对滦河干流上中下游河段表层沉积物、植物群落和底栖动物调查分析，采用生物毒性效应系数法和综合潜在生态风险指数法评价沉积物重金属污染特征，采用植被物种多样性指数和底栖动物完整性指数评价滦河植物和底栖动物群落特征，探究岸带湿地沉积物重金属空间分布与植被及底栖动物群落特征之间关系。结果表明，滦河表层沉积物总体呈清洁水平，但不同河段重金属空间分布差异较大，下游重金属生态危害系数和潜在生态风险指数高于上中游。湿地物种调查共识别维管束植物219种，大型无脊椎底栖动物105种，综合评价结果表明下游植物群落物种多样性和底栖动物群落完整性低于上中游。滦河下游岸带湿地沉积物重金属对生物群落具有生物毒性和潜在的生态风险，降低了植被物种多样性和底栖动物群落完整性。大型底栖动物完整性指数能够综合反映底栖动物群落结构特征变化，对河岸带湿地生态健康评价和监测具有重要意义。

Relationship of the heavy metals distribution in sediments to vegetation diversity and macroinvertebrate communities in riparian wetlands

River habitat integrity plays a key role in maintaining the safety and health of environment, ecology, and hydrology of rivers. To investigate the relationship of the distribution of heavy metals in sediments to vegetation diversity and macroinvertebrate communities in riparian wetlands, the surface sediments, vegetations and benthic invertebrates were sampled in Luanhe River. Six heavy metals, including Ni, Cr, Zn, Cu, Pb and Cd, were measured. Effects range-median quotient and integrated potentially ecological risk index were calculated to evaluate the pollution characteristics of heavy metals. The biological communities were assessed with the application of vegetation diversity index and benthic macroinvertebrate-based index of biotic integrity (B-IBI). The results showed that the surface sediments of Luanhe River were at clean status, but the distribution of heavy metals varied substantially in different sections. Along the river, the ecological harm index and potential ecological index were the highest at the lower reaches. A total of 219 vascular plant species and 105 macroinvertebrate species were collected in Luanhe River. The plant diversity and benthic macroinvertebrate integrity was lower in the downstream than in the middle and up stream. Overall, heavy metals in sediments of the downstream showed a high potentially biological toxicity on biological communities in Luanhe River, reducing the vegetation species diversity and benthic community integrity in the riparian wetlands. The B-IBI reflects the change of the structural characteristics of benthic macroinvertebrate communities effectively and has significant implications in assessing ecological health of riparian wetlands.