唐山城市土壤重金属污染及潜在生态危害评价

An assessment of the heavy metal pollution and potential ecological hazards in urban soil of Tangshan City

以唐山城市土壤为对象,采用单因子指数法和尼梅罗综合指数法对土壤重金属的环境质量及污染特征进行评价,并采用Hakanson的潜在生态危害指数法对土壤中重金属的潜在生态危害进行评价。结果表明,没有重金属元素出现污染状态,其中Hg、Ni、Cr、As都处于清洁状态,Pb、Zn、Cu绝大部分样点处于清洁状态,7.94%、6.35%、1.59%处于安全状态,Cd元素绝大部分样点处于清洁安全状态,只有1.59%处于警戒状态;综合污染评价土壤环境整体优良,清洁、安全土壤面积比例分别为98.41%、1.59%,没有出现警戒和污染土壤;各重金属元素中,产生潜在生态危害的重金属主要是Hg,已达到强潜在生态危害水平,其余重金属均为轻度潜在生态危害,综合考虑多种重金属的潜在生态危害性,其轻微生态危害、中等生态危害、强生态危害、很强生态危害的百分比分别是73.02%、26.98%、0%、0%,整体表现为轻微潜在生态危害。

With the urban soil of Tangshan City as the study target,the authors evaluated the environmental quality of soil heavy metals and pollution characteristics by adopting the single factor index method and Nemerow comprehensive index method.Besides,the potential ecological hazard index suggested by Hakanson was used to assess the ecological hazards of heavy metals in urban soil.All of the heavy metal elements are not in the pollution state,especially all of Hg,Ni,Cr and As are in a clean condition.Most of Pb,Zn and Cu are in a clean condition,with only 7.94% of Pb,6.35% of Zn and 1.59% of Cu in a safe state.Most of Cd are in a clean and safe condition,with only 1.59% of Cd in an alert state.On the whole,the integrated pollution assessment shows that the soil environment is good,with clean,safe,alert and contaminated soil area possessing 98.41%,1.59%,0 % and 0% respectively.As for the heavy metal elements,Hg is mainly responsible for potential ecological hazard,and its content has reached the high potential ecological hazard level;other heavy metals only cause small potential ecological hazards.Considering synthetically the potential ecological hazards of heavy metals,the authors have found that the percentage of small,medium,high and strong ecological hazard is respectively 73.02%,26.98%,0% and 0%.Therefore,the general performance is the small potential ecological hazard.