摘要
生物质能是我国和世界各国开发和利用的重要可再生能源,然而生物质能电厂对周边环境的污染和安全评价尚处于空白.为了解与评价生物质能电厂周边土壤重金属元素的污染状况,按照点源扇形布点原则,在生物质能电厂周边四个方位不同距离布点采样,以远离电厂区域为对照点,共采集26个土壤样品,分析检测了Cr、Mn、Ni、Cu、Zn、As、Se、Ag、Cd、Sb、Hg和Pb等12种重金属元素的含量.分析结果显示,Cr、Ni、Cu、As、Se、Ag和Cd等7种重金属元素平均含量高于安徽省土壤平均背景值,土壤中Cr污染最明显,平均浓度为246.5 mg·kg^(-1)(48.9—1267.4 mg·kg^(-1)),平均超《土壤环境质量》(GB 15618—2018)(6.5<pH≤7.5)中土壤污染风险筛选值的3.4倍(1.1—6.3倍),最大超标点位于主导风下风向1000 m,在常年主导风下风向土壤中Cr、Cd和Sb的含量高于对照点,差异具有统计学意义(P=0.03);与国内外对其他燃煤电厂周边土壤的研究报道相比,生物质能电厂周边土壤中Cr的含量水平远高于文献报道.单因子污染指数法分析显示,Cr的污染最严重,其次是Se,危险等级为重污染,Cd为中度污染,污染点位分布在常年主导风下风向和次主导风下风向.内梅罗综合指数法分析显示,电厂周边土壤普遍受到了重金属元素污染,在常年主导风下风向和次主导风下风向分别为5.2和4.1,属重度污染,其他方向和对照区内梅罗综合指数为2.7和1.6,属中度和轻度污染.综合潜在生态风险分析显示,Cd、Hg、Cr和As对综合潜在生态风险贡献较大.基于主成分分析的结果,综合考虑生物质能电厂周边土壤中各重金属元素的含量和空间分布特征以及相关性分析和聚类分析结果,将12种重金属元素分为4类:(1)Mn、Ni、Zn、As、Se、Ag、Sb和Pb,(2)Cr和Cd,(3)Hg,(4)Cu,其中第1类和第3类来源主要受土壤母质影响,第2类中Cd和第4类Cu来源主要受农业活动,Cr则很可能源于生物质焚烧烟气的扩散沉降及其在土壤中的累积,在生物质能电厂周边的土壤重金属元素污染调查中Cr污染应受到重点关注.
Biomass energy was an important renewable energy source developed and utilized by China and the rest of the world.However,it was still in a blank in the polluted evaluation of biomass power plants and the safety assessment of the surrounding environment.In order to investigate and evaluate the pollution levels of heavy metals in the soil around biomass power plants,according to the principle of point source sector layout,a total of 26 soil samples were collected at four different distances around the biomass power plant,and away from the power plant area.According to the《Technical Specifications for Soil Environmental Testing》(HJ/T 166—2004),the contents of 12 heavy metals such as Cr,Mn,Ni,Cu,Zn,As,Se,Ag,Cd,Sb,Hg and Pb were analyzed.The results showed that the average content of seven heavy metals such as Cr,Ni,Cu,As,Se,Ag and Cd were higher than the average background value of Anhui Province,and the content of Cr,Cd and Sb in its perennial dominant wind downwind direction were higher than that of the control Point,the difference was statistically significant(P=0.03).The Cr pollution in the soil was the most obvious,with an average concentration of 246.5 mg·kg^(-1)(48.9—1267.4 mg·kg^(-1)),which was 3.4 times(1.1—6.3 times)higher than the second-level limit of the National Soil Environmental Quality Standard.The maximum over-standard point was 1000 m of the perennial dominant wind downwind direction.Compared with domestic and foreign research reports on soils around other coal-fired power plants,the levels of Cr in soils around biomass power plants were much higher than those reported in the literature.The single factor pollution index method analysis showed that Cr had the most serious pollution,followed by Se,the hazard level was heavy pollution,Cd was moderate pollution,and the pollution point was distributed in the perennial dominant wind downwind direction and sub-dominant wind downwind direction.The Nemero comprehensive index method analysis showed that the soil around biomass power plants were generally polluted by heavy metals.The perennial dominant wind downwind direction and sub-dominant wind downwind direction were 5.2 and 4.1 respectively,which were heavy pollution,and the Mero comprehensive index in other directions and control areas for 2.7 and 1.6,it was moderately and slightly polluted.The comprehensive potential ecological risk analysis showed that Cd,Hg,Cr and As contributed a lot to the comprehensive potential ecological risk.In summary,the soil around the biomass power plant was polluted by different levels of heavy metals.The unique pollution characteristics of Cr deserve serious attention in pollution monitoring in soils surrounding the biomass power plants,and the pollution was mainly concentrated in the perennial dominant wind downwind direction,sub-dominant wind downwind direction,dominant wind downwind direction 45 degrees angle,the distance was 500 and 1000 m.Based on the results of principal component analysis,considering the content and spatial distribution characteristics of heavy metals in the soil around the biomass power plant,as well as correlation analysis and cluster analysis results,12 heavy metal elements were divided into 4 categories:(1)Mn,Ni,Zn.,As,Se,Ag,Sb and Pb;(2)Cr and Cd;(3)Hg;(4)Cu.Among them,the first and third sources were mainly affected by soil parent material;the second type of Cd and the fourth type of Cu source were mainly affected by agricultural activities;Cr was likely to be derived from the diffusion sedimentation of biomass incineration flue gas and its in soil.Accumulation,Cr pollution should be paid attention to in the investigation of soil heavy metal element pollution around biomass power plants.
作者
吕占禄
张金良
张晗
邹天森
刘凯
王慢想
LV Zhanlu;ZHANG Jinliang;ZHANG Han;ZOU Tiansen;LIU Kai;WANG Manxiang(State Environmental Protection Key Laboratory of Ecological Effect and Risk Assessment of Chemicals,State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Environmental Health Risk Assessment and Research Center,Beijing,100012,China)
出处
《环境化学》
CAS
CSCD
北大核心
2020年第12期3480-3494,共15页
Environmental Chemistry
关键词
生物质能电厂
表层土壤
重金属元素
污染特征
潜在生态风险评价
铬
biomass power plant
surface soil
heavy metal
pollution characteristics
potential ecological risk
chromium
