南昌市街道灰尘重金属时空分布特征及健康风险评估

分析了南昌市夏季和冬季街道104个灰尘样品中的V、Cr、Co、Ni、Cu、Zn、As、Cd和Pb含量，并利用地积累指数（Igeo）计算其污染程度，并参考美国国家环保局(US EPA)推荐的健康风险模型评价灰尘重金属暴露的人体致癌和非致癌风险，通过主成分和相关分析识别南昌市灰尘重金属的可能来源。结果表明：南昌市街道灰尘中重金属Cr、Ni、Cu、Zn、Cd和Pb含量均显著高于江西省土壤背景值，而V、Co和As含量与江西省土壤背景值含量相近。重金属V、Co和As含量无显著季节差异，但冬夏季节含量的空间异质性较高，而Cu在季节和空间分布上均表现出显著的季节差异，其它重金属的高值区均分布在南昌市中心及老工业园附近；Igeo结果表明Cd、Cu、Zn和Cr的污染程度相对较高，而V、As和Co污染程度较轻；重金属3种暴露途径的风险排序为手-口暴露>皮肤接触暴露>呼吸暴露，其中儿童会遭受更大的非致癌风险。除了灰尘As和Cr对儿童的暴露在局部区域HQ和HI值大于1，其它重金属对不同人群的HQ和HI值均小于1。总体而言，南昌市灰尘重金属的致癌风险CR均在安全阈值范围内，大小排序为Cr > As > Co > Ni > Cd。南昌市灰尘重金属的来源广泛，其中As、Co和V主要来源于岩石风化，其它重金属元素主要来源于交通和工业等人类活动。 关键词： 街道灰尘；重金属；时空分布；健康风险；南昌市

Spatial-Temporal Distribution and Health Risk Assessment of Heavy Metals in Street Dust of Nanchang

In this study,the concentrations of V,Cr,Co,Ni,Cu,Zn,As,Cd and Pb in 104 street dusts from Nanchang city in winter and summer were determined. Geo-accumulation index (Igeo ),health risk model recommended by USEPA,and multivariate statistical methods (principal component analysis and correlation analysis) were applied to evaluate the pollution degree, calculate the non-carcinogenic risk (HI ) and carcinogenic risk (CR) (for children and adult),and identify the possible source of heavy metal,respectively. The result showed that the concentrations of Cr,Ni,Cu,Zn,Cd and Pb in street dust of Nanchang were significantly higher than soil background values of Jiangxi Province,while concentrations of V,Co,and As were comparable to corresponding background values. Concentrations of V,Co,and As had not significant seasonal difference,but had high spatial heterogeneity. Cu concentration had significant difference both in seasonal and spatial distribution. The high level area of the other investigated metals mainly distributed in central Nanchang and old industrial area. The result from Igeo indicated that Cd,Cu,Zn,and Cr had higher pollution degree,while V, As,and Co had lower degree. The health risk from three exposures sequenced as hand-mouth ingestion＞dermal contact＞ inhalation,and the child suffered the higher risk than the adult. The HQ and HI of all investigated metals were below one,except the HQ and HI of As and Cr exceed one in some sites. The Carcinogenic risk from metals in street dust were limited within the safe threshold range,and the sequence followed Cr ＞ As ＞ Co ＞ Ni＞ Cd. There were various sources of metals in street dust from the Nanchang city,As,Co and V were mainly derived from rocks weathering,while the other metals came from the anthropogenic activities including the traffic and industry.