Nicholas School of the Environment, Duke University, P.O. Box 90328, Durham, North Carolina 27708, United States.
School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana 47405, United States.
Environ Sci Technol. 2021 Jun 15;55(12):7981-7989. doi: 10.1021/acs.est.1c00546. Epub 2021 May 21.
This study analyzed the impact of urban-soil pedogenesis on soil lead (Pb) contamination from paint and gasoline in the historic core of Durham, North Carolina. Total soil Pb in 1000 samples from streetsides, residential properties, and residual upland and floodplains ranged from 6 to 8825 mg/kg (mean = 211 mg/kg), with 50% of samples between 50 and 200 mg/kg soil Pb. The highest Pb concentrations were within 1 m of pre-1978 residential foundations, with concentrations inversely correlated with house age. Streetside soil Pb concentrations were elevated over the geologic background of <30 mg/kg and correlated with traffic flow. Streetside soil Pb concentrations were lower than Durham streetside soils collected in the 1970s, which was attributed to urban pedogenesis, the complex of natural and human processes that change soils over time. Accelerated erosion redistributes legacy Pb and floodplain sampling indicates sedimentation rates of up to 4 mm/year. Mixing and burial of soil with elevated Pb are also lowering soil Pb concentrations over time. These mechanisms are likely of greater significance on streetsides than near foundation soils. The development of an urban-pedogenesis framework can help guide public health approaches to Pb exposure by incorporating pedogenic processes that reduce and dissipate soil Pb contamination.
本研究分析了城市土壤成土作用对北卡罗来纳州达勒姆历史核心区油漆和汽油导致的土壤铅（Pb）污染的影响。来自街边、住宅物业以及残留高地和洪泛区的 1000 个样本中的总土壤 Pb 含量范围为 6 至 8825mg/kg（平均值为 211mg/kg），其中 50%的样本的土壤 Pb 含量在 50 至 200mg/kg 之间。最高 Pb 浓度出现在 1978 年前住宅基础内 1m 范围内，浓度与房屋年龄呈反比。街边土壤 Pb 浓度高于<30mg/kg 的地质背景值，并与交通流量相关。街边土壤 Pb 浓度低于达勒姆在 20 世纪 70 年代采集的街边土壤 Pb 浓度，这归因于城市成土作用，即自然和人为过程的综合体，随着时间的推移改变土壤。加速侵蚀重新分配了遗留的 Pb，而洪泛区采样表明，每年的沉降速率高达 4mm。土壤中 Pb 含量升高的混合和掩埋也会随着时间的推移降低土壤 Pb 浓度。这些机制在街边比在基础土壤附近可能更为重要。城市成土作用框架的发展可以通过纳入减少和消散土壤 Pb 污染的成土作用过程，帮助指导针对 Pb 暴露的公共卫生方法。
