兰州BRT沿线站台灰尘及其两侧绿化带土壤重金属污染及健康风险评价

本研究以兰州快速公交系统(BRT)沿线站台及其两侧绿化带为研究对象,分析兰州BRT沿线站台灰尘及其绿化带土壤Cu、Pb、Cr、Zn和As等重金属含量,利用内梅罗指数法、美国环境保护署健康风险评估模型及相关性分析对研究区灰尘与土壤重金属的含量特征、污染程度、健康风险及可能的污染源进行分析和评价。结果表明,除北侧绿化带土壤As之外,兰州BRT沿线站台灰尘与两侧绿化带土壤重金属平均含量均高于甘肃省土壤背景值,Zn和Cr的累积水平相对较高;内梅罗综合污染指数法研究表明,BRT沿线站台灰尘重金属为重度污染且南侧绿化带土壤污染程度较北侧严重;健康风险评估结果表明,BRT站台灰尘与两侧绿化带土壤重金属对成人和儿童具有非致癌健康风险,站台灰尘和南侧绿化带土壤As、Cr、Pb与北侧绿化带土壤As、Cr是儿童的主要非致癌因子;站台灰尘中Cr和As不具有致癌风险而两侧绿化带土壤Cr和As对周围人群具有致癌风险。源解析显示,站台灰尘与两侧绿地土壤Cu、Pb、Cr、Zn与交通源有关,As可能与交通源和人为源有关。

Contaminations and Health Risks of Heavy Metals from the Roadside Greenbelt Soils and Dust along the BRT Platform in Lanzhou

In this study, concentrations of heavy metal elements Cu, Pb, Cr, Zn, and As in soil and dust samples collected from the greenbelt in south and north sides of the bus rapid transit (BRT) and its platform along the BRT in Lanzhou were analyzed, aiming to (1) analyze the distribution pattern and contamination levels of heavy metals; (2) evaluate the potential health risks; (3) determine the potential sources of heavy metals in the greenbelt soil from two sides of the BRT and the dust in the BRT platform of Lanzhou. The Nemerow index, and a health risk assessment model proposed by the United States Environmental Protection Agency were used to assess the content characteristics, the degree of pollution, and health risk. Correlation analysis was used to determine the primary sources of pollution. Our results showed the mean concentrations of all the heavy metals in soil and dust from the investigated areas exceeded their corresponding background level in soils in Gansu Province except As from the north greenbelt soil of the BRT platform. Zn and Cr had a greater accumulation than the other heavy metals in soil and dust. The integrated Nemerow pollution index indicated that heavy metals in dust along the Lanzhou BRT were at high levels of heavy metal pollution. Moreover, the pollution level of the metals in the south greenbelt soil of the BRT platform was higher than that of the north side. The human health risk assessment model suggested that all the five heavy metals from the study areas are carcinogenic for adults and children. For children, As, Cr, and Pb in dust and soil from the BRT platform and greenbelt in the south are non-carcinogenic, whereas As and Cr from the greenbelt soil in the north are non-carcinogenic. Moreover, Cr and As in dust along the Lanzhou BRT had no carcinogenic risk, whereas both of them in the greenbelt soil of two sides of the BRT platform had carcinogenic risk for the surrounding people''s health. The pollution source analysis showed that Cu, Pb, Cr, and Zn in dust and soil from the BRT platform and greenbelt soil of both sides of the BRT platform were related to traffic emission, and As was likely to the mixed sources of traffic emission and human activity.