草原型露天煤矿区土壤重金属含量的空间分布特征和污染状况，关系到矿山开采与生态环境修复政策的制定，同时也是研究煤炭开发影响范围的参考指标之一。本文通过分析矿区采场周边土壤重金属含量，评价矿区土壤重金属污染程度，分析土壤重金属的空间异质性，作为从重金属污染视角研究煤炭开采影响的“类型”与“边界”，以及确定生态修复措施的参考依据之一。以宝日希勒一号露天矿采场为中心，从采场边缘向外4 km范围内沿西、西北、北、东北、东、南6个方向设置辐射状的调查样线，共布设了58个土壤采样点。距采场边界0~2 km采样间隔为200 m，2~4 km采样间隔为400 m。在土壤样品采集与处理的基础上，应用内梅罗指数法、地质累积指数法和潜在生态危害指数法，对宝日希勒露天矿区周边土壤重金属污染水平及潜在生态危害进行评价。采用单因素方差分析法分析采场外4 km范围内土壤重金属含量在不同方向上随采场距离的变化特征，判断采煤活动是否对采场外土壤重金属含量造成影响及影响边界。通过对土壤重金属含量进行相关分析，探索不同土壤重金属元素是否具有相同的来源。研究结果表明:① 与土壤环境质量(GB 15618—1995)Ⅰ级标准相比，宝日希勒矿区土壤重金属中Pb，Zn和Cr均未超标，Cu超标率为28%，但未超过国家Ⅱ级标准，对农牧业生产、人体健康和环境基本没有影响。② 以内蒙古土壤背景值为标准，Pb，Cu部分无污染，部分中度污染，Zn和Cr没有污染。综合污染程度指数处于“警戒线”水平。潜在生态危害指数<150，处于轻微生态风险等级。③ 在附近有道路分布的西、西北方向及S201省道附近的采样点上，Pb含量相对较高。④ Zn与Cu在东方向，Pb与Cu在北方向具有较强的相关性，各元素之间在其他方向均未表现出较强的相关性。Pb，Cr，Zn和Cu含量与采场距离关系不密切，没有呈现距离衰减特征。⑤ 参照2018年颁布实施的《土壤环境质量 农用地土壤污染风险管控标准(试行)》(GB 15618—2018)，各项土壤重金属含量远低于规定的风险筛选值，土壤污染风险低，可以忽略。宝日希勒矿区采场外4 km范围内土壤重金属含量总体上处于无污染状态。各方向Pb，Cr，Zn和Cu含量均未表现出距离衰减特征，个别土壤采样点重金属含量相对高，附近分布有道路、居民点、电厂等，与煤矿直接开采关系不明显。

The soil heavy metal content in grassland open-pit coalmine area is related to the policies making on coal mining and ecological restoration. It can provide an important reference for analyzing the impact range of coal mining. The content of heavy metals in the soil around the pit in the mining area was analyzed to define the impact types and boundaries of coal mining from the perspective of heavy metal pollution. The sampling lines were centered on the Baorixile No. 1 open-pit coalmine,set radially from edge of the pit outward to west,northwest,north,northeast,east and south. After the collection and processing of soil samples,Nemero comprehensive pollution index,Geo-accumulation in- dex and Potential ecological risk index were used to evaluate the pollution level of the heavy metals in the soil sur- rounding the pit. The one-way analysis of variance was used to analyze the change characteristics of soil heavy metal content with distance to the pit in different directions. It helped to assess whether the mining activities had an obvious influence on soil heavy metal content outside the pit and whether there was a certain influence range. Through correla- tion analysis,it could find out whether different heavy metal elements in the soil had the same source of soil pollution. The study shows that ① according to the content of heavy metals in the soil around the pit,Pb,Zn and Cr does not ex- ceed the first level specified in National Standard of Soil Environment Quality (GB 15618—1995) in the study area, except that the content of Cu has an over-standard rate of 28% . However,none of them exceed the second level of na- tional standards,which means that the heavy metal content in the soil around the pit has no serious effect on the human health. ② The content of Pb and Cu in partial soil samples has exceeded the background values of heavy metal ele- ments in the soil of Inner Mongolia,while the content of Zn and Cr in all soil samples are within the background val- ues. The comprehensive pollution level has reached the level of “warning line”,which should be a cause for concern. Because the potential ecological risk index is less than 150,the degree of soil pollution around the pit is relatively slight. ③ The content of Pb is universally high in the west and northwest of the pit,where road S201 is located nearby. ④ There are close correlations between Zn and Cu in the eastern pit,as well as between Pb and Cu in the northern pit. However,the other heavy metals are not significantly correlated with each other in all directions. Besides,the con- tent of Pb,Cr,Zn and Cu has no significant correlation with the distance from the edge of the pit,which means that the content of heavy metal does not show a significant downtrend with the increasing distance from the stope. ⑤ According to soil environmental quality risk control standard for soil contamination of agricultural land ( GB 15618—2018),the content of various soil heavy metals is far lower than the specified risk value,and the risk of soil pollution is very low. The study concludes that the content of soil heavy metals within 4 km away from the pit in Baorixile mining area is generally in the state of non-pollution. The soil samples with comparatively high heavy metal content are distributed near to residential areas,power plants and transportation routes. The content of Pb,Cr,Zn and Cu does not show a sig- nificant downtrend with the increasing distance from the pit.