西部某机械加工企业酸洗场地环境调查与污染特征分析

以西北高原地区某铁塔厂酸洗车间为重点区，对场地开展系统的环境调查，结果表明：该场地以重金属锌污染为主要污染因子，场地内土壤Zn浓度范围13.68~68 800 mg·kg-1，局部区域土壤pH异常、土壤Fe含量和Cl-浓度升高现象；土壤Zn污染垂向迁移深，多数点位Zn污染（Zn含量超过200~500 mg·kg-1）深度达10 m以上，少数点位污染深度达15 m以下，其中北区酸池5 m以内、南区酸池3 m以内和下水管道及两侧区域3~10 m深度范围内为重污染；场地土壤pH异常范围与锌污染范围一致，土壤Cl-浓度和Fe浓度与Zn浓度具有相关性，可作为判断土壤锌污染程度和范围的辅助因子；现场速测的Zn含量与实验室总量测定结果一致性强，在pH异常区域的现场速测pH值与实验室测定结果的一致性较好，现场速测结果可作为污染表征的基础依据。推测酸池泄漏、含重金属洗液长期下渗和工业废水的直接排放为场地污染主要原因。

Contamination investigation and characteristics analysis of the pickling site in a mechanical processing factory in the Western Plateau Area,China

This study investigated a contaminated site located at an iron tower factory in the Northwest Plateau Area of China,and in particular,sampling was conducted in the vicinity of the pickling workshop.The following results were obtained. Zn was determined to be the most important pollutant at the site,and concentrations of Zn varied between 13.68 and 68 800 mg·kg-1.In some areas,the soil pH levels were abnormally low and the concentrations of Cl- and Fe were relatively high. Vertical transportation of Zn in the soil was evident at the depths with abnormal Zn concentrations (i.e.,greater than 200 to 500 mg·kg-1);most sampling points extended to 10 m below the surface,but a few points reached as far as 15 m below the surface.Soils above 5 m in the north area acid pools,soils above 3 m in the south area acid pools,and soils between 3 and 10 m depth in the pipeline area were all heavily polluted. The areas with abnormal pH values were consistent with the Zn contaminated areas,and the concentrations of Cl- and Fe were strongly correlated to the concentration of Zn.Thus,these other endpoints may be useful for assessing additional Zn contamination at the site. The X-ray fluorescence (XRF) results for Zn in the field were consistent with the laboratory-based analysis results,and furthermore,the rapid measurements of pH in the abnormal areas showed a good match to the laboratory-based analysis results,which means that rapid measurements may be valid to use for assessing the contamination at the site.It is speculated that the main cause of Zn contamination was long-term leaching from solutions and wastewater containing heavy metals,as these materials were discharged directly at the site in the past.