呼伦贝尔市城郊河岸带土壤与河流沉积物重金属污染现状分析

Analysis on the current heavy metal pollution situation in the riparian zone and river in the suburbs and urbans of Hulun Buir

河岸带类型对河流环境重金属富集具有显著影响,合理规划河岸环境,可以减缓河流周围土地的重金属污染对河流生态系统的影响。随着内蒙古自治区呼伦贝尔市工矿业、农牧业和旅游业的快速发展,频繁的人类活动会增加对河流周边重金属污染潜在威胁。为揭示呼伦贝尔市河流域环境重金属污染的现状、分布特征以及不同的河岸带类型对河流沉积物重金属污染的影响,在该区域采集了34个河岸带表层土壤和河流表层沉积物样品,并测定了6种重金属(Cr、Cu、Mn、Ni、Pb与Zn)含量,采用污染负荷指数法(pollution load index,PLI)对重金属污染情况进行评价。结果显示:6种重金属的平均含量分别为背景值的2.08倍、1.55倍、0.80倍、1.61倍、0.82倍、1.00倍,总体PLI为1.19,属轻度污染;河岸带的重金属污染程度总体高于河流,但是河流的重金属污染变率更大,相比之下重金属含量的最高值多出现于河流中;不同河岸带类型的PLI呈工业型河岸最高(1.535)、自然型河岸次之(1.126)、城市绿化河岸最低(1.030)、工矿业活动是区域重金属污染的主要源头,城市绿化型河岸带与自然型河岸带具有一定的缓解重金属污染累积的作用。

Background,aim,and scope The potential threat of heavy metal pollution to rivers increases due to rapid development of industry,mining,agriculture,animal husbandry,tourism,frequent human activities and improper planning of riparian zones in Hulun Buir,Inner Mongolia Autonomous Region.We therefore investigate the distribution characteristics of heavy metal pollution in the river areas of Hulun Buir and the influence of different riparian types(urban greening type,natural type and industrial type)on the enrichment of heavy metal pollution in the rivers on the Hailar River Basin.Materials and methods A total of 34 riparian surface soil and river surface sediment samples were collected in the Hailar River.The contents of six heavy metals(Cr,Cu,Mn,Ni,Pb,and Zn)were determined by elemental mass spectrometry,and the pollution load index(PLI)method was used to evaluate the heavy metal pollution level.Results The results show that the average content of these six heavy metals were 2.08,1.55,0.80,1.61,0.82,and 1.00 times of the background value,respectively.An overall PLI of 1.19 indicated light pollution occurred.The PLI was highest in industrial river banks(1.535),intermediate in natural river banks(1.126),and lowest in the urban greenbelt river banks(1.030).Discussion The pollution level of heavy metals in the riparian zone was generally higher than that in the rivers.However,the variability of heavy metal pollution in rivers was comparatively greater,with the highest heavy metal content occurring in rivers.The river environment may have a certain purification effect on heavy metal pollution compared with the terrestrial environment.The natural type riparian zone may have a stronger purification effect on heavy metal pollution.The industrial activities could be the main source of heavy metal pollution in the region.Conclusions The overall heavy metal pollution remains a low level,and its content has not yet reached the level that could endanger human health.The urban greenbelt and natural riparian zone could reduce the heavy metal accumulation in rivers.Recommendations and perspectives During the process of the urbanization,continuous monitoring of heavy metal pollution and urban planning schemes are necessary for reducing the potential threat of heavy metal pollution.