School of Environment, Tsinghua University, Beijing 100084, China.
Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea.
Environ Int. 2019 Mar;124:320-328. doi: 10.1016/j.envint.2019.01.024. Epub 2019 Jan 17.
Potentially toxic elements such as heavy metals are ubiquitous in the environment. Risk-based environmental management relies upon identifying pollution sources, pathways, and the exposed population. In a Chinese urban setting, many residents live in high-rise buildings without private gardens. Therefore, the main residential risk of exposure to contaminated soils and dusts may be associated with public open spaces. As children are the most vulnerable receptor, playgrounds represent an important yet often overlooked exposure point. The present study assessed plausible sources of heavy metals at children's playgrounds in a representative metropolitan environment. Soil and equipment dust samples were collected from 71 playgrounds across Beijing, which were analyzed for 11 different heavy metals. Principal component analysis (PCA) was used to identify the latent constructs which control heavy metal variability and reflect potential sources. Cluster analysis (CA) was conducted to group sampled locations, which provided further insights on plausible sources. The main factors extracted from the PCA were then subject to geostatistical analysis. The systematic combination of GIS with multivariate statistical analysis proved valuable for elucidating anthropogenic and natural sources. Elevated Be, V, Cr, Mn, Co, Ni, As in playground soils were found to derive mainly from the natural background (spatial autocorrelation = 2 km), while elevated Cu and Pb was attributed to traffic activities (spatial autocorrelation = 17 km), especially along the routes of Beijing's inner ring-roads, the major roads toward the northwest and northeast, and the international airport. These results suggest that heavy metals in playground equipment dust may derive mainly from atmospheric deposition of air pollution of both natural and anthropogenic origin (spatial autocorrelation = 11-13 km). Among them, Be, V, Mn, Co, Cu, As, Pb were attributed to atmospheric pollution deriving from the north of Beijing, brought by the prevailing northern wind in the winter season; whereas, Cr and Ni may possibly be brought from the southeast by the summer season winds. Knowledge of anthropogenic vs. natural origins of heavy metals in playgrounds is critical in assessing health impact and designing policy instruments for metropolitan areas.
潜在有毒元素（如重金属）在环境中无处不在。基于风险的环境管理依赖于识别污染源、途径和暴露人群。在中国城市环境中，许多居民居住在没有私人花园的高层建筑中。因此，接触受污染土壤和灰尘的主要住宅风险可能与公共开放空间有关。由于儿童是最脆弱的受体，游乐场是一个重要但经常被忽视的暴露点。本研究评估了在具有代表性的大都市环境中儿童游乐场中重金属的可能来源。从北京的 71 个游乐场采集了土壤和设备灰尘样本，并对 11 种不同的重金属进行了分析。主成分分析（PCA）用于识别控制重金属变异性并反映潜在来源的潜在结构。聚类分析（CA）用于对采样地点进行分组，这为潜在来源提供了更深入的见解。然后对 PCA 提取的主要因素进行地质统计学分析。GIS 与多元统计分析的系统组合对于阐明人为和自然来源非常有价值。发现游乐场土壤中升高的 Be、V、Cr、Mn、Co、Ni、As 主要来自自然背景（空间自相关=2 公里），而升高的 Cu 和 Pb 归因于交通活动（空间自相关=17 公里），特别是在北京内环路、西北和东北方向的主要道路以及国际机场沿线。这些结果表明，游乐场设备灰尘中的重金属可能主要来自大气对自然和人为来源空气污染的沉积（空间自相关=11-13 公里）。其中，Be、V、Mn、Co、Cu、As、Pb 归因于冬季盛行北风从北京北部带来的大气污染；而 Cr 和 Ni 可能是夏季东南风带来的。了解重金属在游乐场中的人为与自然来源对于评估健康影响和为大都市地区设计政策工具至关重要。
