Wang Zhen, Wade Anna M, Richter Daniel D, Stapleton Heather M, Kaste James M, Vengosh Avner
Nicholas School of the Environment, Duke University, Durham, NC 27708, USA.
U.S. Environmental Protection Agency (EPA), Cincinnati, OH 45268, USA.
Sci Total Environ. 2022 Feb 1;806(Pt 3):151276. doi: 10.1016/j.scitotenv.2021.151276. Epub 2021 Oct 27.
Anthropogenic lead (Pb) in soils poses risks to human health, particularly to the neuropsychological development of exposed children. Delineating the sources and potential bioavailability of soil Pb, as well as its relationship with other contaminants is critical in mitigating potential human exposure. Here, we present an integrative geochemical analysis of total elemental concentrations, radionuclides of Cs and Pb, Pb isotopic compositions, and in vitro bioaccessibility of Pb in surface soils sampled from different locations near Durham, North Carolina. Elevated Pb (>400 mg/kg) was commonly observed in soils from urban areas (i.e., near residential house foundation and along urban streets), which co-occurred with other potentially toxic metal(loids) such as Zn, Cd, and Sb. In contrast, soils from city parks and suburban areas had systematically lower concentrations of metal(loids) that were comparable to geological background. The activities of Cs and excess Pb, coupled with their correlations with Pb and co-occurring metal(loids) were used to indicate the persistence and remobilization of historical atmospherically deposited contaminants. Coupled with total Pb concentrations, the soil Pb isotopic compositions further indicated that house foundation soils had significant input of legacy lead-based paint (mean = 1.1895 and 2.0618 for Pb/Pb and Pb/Pb, respectively), whereas urban streetside soils exhibited a clear mixed origin, dominantly of legacy leaded gasoline (1.2034 and 2.0416) and atmospheric deposition (1.2004-1.2055 and 2.0484-2.0525). The in vitro bioaccessibility of Pb in contaminated urban soils furthermore revealed that more than half of Pb in the contaminated soils was potentially bioavailable, whose Pb isotope ratios were identical to that of bulk soils, demonstrating the utility of using Pb isotopes for tracking human exposure to anthropogenic Pb in soils and house dust. Overall, this study demonstrated a holistic assessment for comprehensively understanding anthropogenic Pb in urban soils, including its co-occurrence with other toxic contaminants, dominant sources, and potential bioavailability upon human exposure.
土壤中的人为铅（Pb）对人类健康构成风险，尤其是对接触铅的儿童的神经心理发育。确定土壤铅的来源、潜在生物可利用性及其与其他污染物的关系对于减轻潜在的人体暴露至关重要。在此，我们对从北卡罗来纳州达勒姆附近不同地点采集的表层土壤中的总元素浓度、铯和铅的放射性核素、铅同位素组成以及铅的体外生物可及性进行了综合地球化学分析。在城市地区（即靠近住宅房屋地基和城市街道沿线）的土壤中普遍观察到铅含量升高（>400 mg/kg），这些土壤还与其他潜在有毒金属（类金属）如锌、镉和锑同时存在。相比之下，城市公园和郊区的土壤中金属（类金属）浓度系统地较低，与地质背景相当。铯和过量铅的活度，以及它们与铅和共存金属（类金属）的相关性，被用来指示历史大气沉降污染物的持久性和再迁移。结合总铅浓度，土壤铅同位素组成进一步表明，房屋地基土壤有来自遗留铅基涂料的大量输入（Pb/Pb和Pb/Pb的平均值分别为1.1895和2.0618），而城市街道旁土壤呈现明显的混合来源，主要是遗留含铅汽油（1.2034和2.0416）和大气沉降（1.2004 - 1.2055和2.0484 - 2.0525）。受污染城市土壤中铅的体外生物可及性进一步表明，受污染土壤中超过一半的铅具有潜在生物可利用性，其铅同位素比率与整体土壤相同，证明了使用铅同位素追踪人类对土壤和室内灰尘中人为铅暴露情况的实用性。总体而言，本研究展示了一种全面评估方法，用于全面了解城市土壤中的人为铅，包括其与其他有毒污染物的共存情况、主要来源以及人类接触时的潜在生物可利用性。
