津北大气干湿沉降重金属元素通量与评价研究

大气干湿沉降是有害物质进入土壤的一种重要途径,是影响农田生态系统安全的重要因素.天津市北部的蓟州区大气干湿沉降重金属元素具有以下特征:(1)大气干湿沉降重金属元素年沉降通量从大到小依次为Zn>Pb>Cr>Cu>Ni>As>Cd>Hg,Zn、Pb是大气干湿沉降重金属元素中最主要的元素,山区年沉降通量小于平原区,表明山区空气环境质量相对于平原区好,与天津城区、北京平原区、全国相比,津北蓟州区大气干湿沉降重金属各元素年沉降通量均相对较低;(2)大气干湿沉降物输入浓度中,Cd、Pb、Zn、Hg显著高于蓟州区土壤含量平均值,尤其是Cd,表明大气干湿沉降可能是土壤中Cd的重要来源;(3)根据大气干湿沉降物环境地球化学评价结果,大气干湿沉降物环境地球化学单指标和综合指标评价结果均为一等,表明该地区大气环境质量很好.

Sedimentation Flux and Its Evaluation of Dry and Wet Atmospheric Deposition of Heavy Metal Elements in North Tianjin

Dry and wet deposition is an important way for harmful substances to enter the soil,and is an important factor to affect the security of farmland ecosystem.The atmospheric deposition of heavy metals in Jizhou District of northern Tianjin city has the following characteristics:(1) Annual sediment flux of heavy metal elements from large to small in turn is Zn > Pb > Cr > Cu > Ni > > As > Cd > Hg,Pb and Zn are the most important elements in the dry and wet atmospheric deposition of heavy metals,the annual sedimentation flux of mountain area is less than that of plain,which indicates that the air environment quality of mountain area is better than that of plain area,compared with the Tianjin urban district,Beijing plain area and the whole country,the annual sediment flux of dry and wet atmospheric deposition of heavy metals in Jizhou district is relatively low;(2) The Cd,Pb,Zn and Hg were significantly higher than the average value of the soil,especially the Cd,which indicated that the dry and wet atmospheric deposition may be an important source of Cd in soil;(3) According to the results of dry and wet atmospheric deposition environmental geochemical evaluation,the results of single index and comprehensive index of dry and wet atmospheric deposition are all one,which indicates that the atmospheric environment quality is very good.