铁路场段土壤重金属含量分布特征及生态风险评价

    Distribution characteristics and ecological risk assessment of heavy metals in soils in railway depots

    • 摘要: 铁路交通运输是土壤重金属元素的重要潜在来源,为探究铁路场段土壤重金属空间分布规律以及污染程度,选取我国北方某铁路机务段、车辆段和编组场作为研究对象,测定机务段、车辆段各16处和编组场6处样点的土壤重金属(As、Hg、Cd、Pb、Cu和Ni)含量,对比分析铁路各场段土壤重金属的分布特征,阐明相关关系,并采用内梅罗综合污染指数法和Hakanson生态风险评价法评估各场段土壤重金属环境质量和生态风险。研究结果表明: ①研究铁路场段存在重金属积累现象,但积累程度较轻,不存在超标现象; ②机务段土壤Pb、Cd含量和车辆段土壤Cu、Cd、Pb含量空间分布存在差异,重金属积累受人为活动影响较大,机务段油库、洗车机电控楼和锅炉房土壤Pb含量或Cd含量偏高,车辆段锅炉房、变电所、预检预修库、轮对段修间和指挥中心中土壤Cu含量、Pb含量或Cd含量偏高,各场段工艺差异会导致不同重金属在土壤中积累; ③场段土壤Cd含量与Pb含量、As含量呈显著正相关,3种重金属可能受油料燃烧废气、油品存放使用、车辆尾气、铁路煤炭运输等因素影响; ④各场段综合土壤环境质量判定结果均为无污染,土壤生态风险程度处于最低级别。研究结果可为铁路场段设计、运营以及土壤环境影响评价提供参考。

       

      Abstract: Railway transportation is an important potential source of the heavy metals in soils. In order to explore the spatial distribution pattern and pollution level of soil heavy metals in railway depots, the authors selected a locomotive depot, a vehicle depot and a marshalling yard in the northern part of China as the study object and measured the heavy metals (As, Hg, Cd, Pb, Cu, and Ni) content of the respective 16 samples from locomotive depot and vehicle depot, and 6 samples from the marshalling yard. The distribution characteristics of heavy metal in each railway depot were analyzed by comparing with the standards, and their correlation relationships were identified. The environmental quality and ecological risks of heavy metals in the soils of each depot were evaluated by Nemerow comprehensive pollution index and Hakanson ecological risk assessment method. The results are as follows. ① There is a phenomenon of heavy metal accumulation in the railway depot, but the accumulation degree is relatively light without a sign of exceeding the standard. ② The spatial distribution of Pb and Cd content in the locomotive depot and Cu, Cd, and Pb content in the vehicle depot has huge variations. The accumulation of heavy metals is greatly affected by human activities, and Pb and Cd content in the soils of the oil depot, washing workshop, and boiler room of the locomotive depot is higher. Cu, Pb, and Cd content in the soils of the boiler room, substation, pre-inspection and pre-repair warehouse, wheelset overhaul workshop, and command center of the vehicle depot is higher as well. Furthermore, the divergences in the process of each railway depot will lead to the accumulation of different heavy metals in the soil.③ There is a significant positive correlation between Cd content and Pb and As content, and these heavy metals may be influenced by the factors such as oil combustion exhaust gases, storage and usage of oil, vehicle exhaust gases, and railway coal transportation. ④ The results of comprehensive soil environmental quality assessment show that there is no pollution in each depot, and the ecological risk degree of each depot is at the lowest level. This research results could provide references for the design, operation, and soil environmental impact assessment of railway depots.

       

    /

    返回文章
    返回