College of Geography and Environment, Shandong Normal University, Ji'nan, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, PR China.
College of Geography and Environment, Shandong Normal University, Ji'nan, PR China.
Ecotoxicol Environ Saf. 2019 May 30;173:381-392. doi: 10.1016/j.ecoenv.2019.02.019. Epub 2019 Feb 20.
Pollution of potentially toxic metals (PTMs) in road dust (RD) is becoming an important threat to the urban environmental quality and human health. The chemical speciation of PTMs is an important index charactering the risks, which may also closely relate to the pollution level and source but it was poorly understood. In this study, the chemical speciation of Cd, Cr, Cu, Ni, Pb and Zn in the RD of a megacity (Nanjing), China was determined following an optimized BCR (proposed by the European Community Bureau of Reference) sequential extraction procedure to assess their pollution and potential eco-risk and to explore the variations of metal chemical speciation with the pollution levels and sources. Total concentrations of the PTMs in the RD were enriched 1.4- to 123-fold relative to the subsoil with median contamination factors (CF) of 6.7 (Pb), 6.0 (Cu), 5.5 (Cd), 4.0 (Zn), 2.0 (Cr) and 1.9 (Ni). Pollution of the PTMs should be mainly from industrial and traffic emissions and showed high CF values in the northern industrial zone. Whereas, the chemical percentages of each metal showed relatively narrow spatial variations and were not statistically correlated with the pollution levels (p = 0.05). Comparing of similar studies indicates that no regular patterns existed in chemical percentages for each metal in RD polluted by the traffic and/or both the industrial and traffic sources. In the RD of Nanjing, Pb was mostly associated with reducible phase, Cd and Zn were mainly present in acid-soluble phase, Cu was mostly concentrated in oxidizable phase, while Cr and Ni were predominantly present in residual phase. As the typical pollutants, anthropogenic Cd, Cu, Pb and Zn were mostly associated with the potential mobile phases but also with the residual phase in the RD of Nanjing, causing 1.4- to 3.0-fold increase in the mobility. Combining the assessments from eco-risk index, risk assessment code and sediment quality guidelines with the pollution levels and chemical speciation, we deduced that Cd, Cu, Pb and Zn may pose certain eco-risk upon transport into the aquatic system and soil, and Cd should be primarily concerned.
道路灰尘（RD）中潜在有毒金属（PTMs）的污染正成为城市环境质量和人类健康的重要威胁。PTMs 的化学形态是一个重要的风险指标，它可能与污染水平和来源密切相关，但目前对此了解甚少。在这项研究中，采用优化的 BCR（由欧盟参考局提出）顺序提取程序，测定了中国特大城市（南京）RD 中 Cd、Cr、Cu、Ni、Pb 和 Zn 的化学形态，以评估其污染和潜在生态风险，并探讨金属化学形态随污染水平和来源的变化。与底土相比，RD 中 PTMs 的总浓度富集了 1.4 到 123 倍，中值污染因子（CF）分别为 6.7（Pb）、6.0（Cu）、5.5（Cd）、4.0（Zn）、2.0（Cr）和 1.9（Ni）。PTMs 的污染主要来自工业和交通排放，在北部工业区表现出较高的 CF 值。然而，各金属的化学百分比显示出相对狭窄的空间变化，与污染水平没有统计学相关性（p = 0.05）。与类似研究的比较表明，在受交通和/或工业和交通源污染的 RD 中，每种金属的化学百分比没有固定模式。在南京 RD 中，Pb 主要与可还原相结合，Cd 和 Zn 主要存在于酸可溶相中，Cu 主要集中在可氧化相中，而 Cr 和 Ni 主要存在于残留相中。作为典型污染物，人为 Cd、Cu、Pb 和 Zn 主要与潜在的可迁移相结合，但也与南京 RD 中的残留相结合，导致其迁移性增加了 1.4 到 3.0 倍。将生态风险指数、风险评估代码和沉积物质量指南的评估与污染水平和化学形态相结合，我们推断 Cd、Cu、Pb 和 Zn 在进入水系统和土壤时可能会造成一定的生态风险，其中 Cd 应是首要关注的。
