中国西北干旱地区典型持久性有机污染物的赋存特征

Occurrence and human exposure of typical persistent organic pollutants in the Northwest China

关键词:  持久性有机污染  有机氯农药  六六六  滴滴涕  多环芳烃  污染来源  暴露风险

Key words:  persistent organic pollutants (POPs)  organochlorine pesticides (OCPs)  hexachlorocyclohexane (HCH)  dichlorodiphenyl trichloroethane (DDT)  polycyclic aromatic hydrocarbons (PAHs)  pollutant sources  exposure risk

摘要:

持久性有机污染物（POPs）是人类工业化生产和生活活动所释放的对环境和人类健康造成潜在危害的新污染物，其具有持久性、生物富集性和高毒性，可以长距离迁移至远离污染源的偏远地区。环境中的POPs具有浓度低、监测难度大、来源复杂等特点。目前华南和华东沿海经济发达地区有较为完善的相关研究，但是对于中国西北干旱地区的研究还相对欠缺。文章总结对比了我国西北干旱地区与东部经济发达地区土壤与空气中的多环芳烃 （PAHs） 与有机氯农药 （OCPs） 的污染水平，探讨了我国西北地区OCPs与PAHs的主要来源及其健康风险。目前我国西北地区有关干旱地区的POPs的研究，主要集中在省会城市，如新疆乌鲁木齐、甘肃兰州，干旱地区的研究仍然有待加强。现有研究表明，西北地区绝大部分城市的健康风险都较低，只有少部分地区处于潜在风险等级；大多POPs具有显著的季节性特征， POPs浓度随着季节不同，健康暴露风险也会有所变化。随着全球气候变暖，原本固存在土壤中的POPs， 也可能会进入到大气中。

Abstract:

Background, aim, and scope With the advancement of urbanization and industrialization, persistent organic pollutants (POPs) released from anthropogenic activities have posed significant threats to the environment and human health. As emerging contaminants, POPs have been restricted under the Stockholm Convention on Persistent Organic Pollutants. In China, extensive studies have been conducted to identify environmental sources of POPs and assess associated human exposure risks. However, existing research has predominantly focused on East China, while studies in Northwest China remain limited. Meanwhile, ongoing global climate change, accompanied by increasing extreme weather events, may further intensify aridity in these regions and alter pollutant exposure pathways. Therefore, this study reviews the occurrence and exposure risks of POPs in arid areas of Northwest China. Materials and methods This review first outlines the physicochemical properties of major organochlorine pesticides (OCPs), with particular focus on hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs), as well as polycyclic aromatic hydrocarbons (PAHs), and briefly summarizes their toxic effects. It then introduces desert and sandy regions in China. Subsequently, the spatial distribution and sources of major OCPs and PAHs in the atmosphere and soil are summarized. Finally, the environmental exposure risks associated with these pollutants are discussed. Results Cities in Northwest China, such as Urumqi and Lanzhou, are less economically developed than Beijing, Shanghai, and Guangzhou. Except for markedly higher DDT concentrations in Beijing soils, levels of major OCPs in soil and air in northwestern cities are generally comparable to those in developed regions. In contrast, polycyclic aromatic hydrocarbons (PAHs) in soil and atmosphere are often higher in Northwest China. OCPs mainly derive from historical residues, with limited recent inputs in some areas, whereas PAHs primarily originate from biomass and fossil fuel combustion, with additional contributions from long-range transport. Overall, concentrations in most arid regions remain within safe ranges. Discussion Although health risks from OCPs and PAHs in arid regions are generally low, atmospheric concentrations show clear seasonal variation. OCPs are typically higher in summer due to temperature-driven volatilization from soil. Conversely, PAHs are lower in summer because enhanced photodegradation exceeds soil emissions, but higher in winter due to coal combustion for heating. Under continued global warming, rising temperatures in arid regions may enhance soil-to-air transfer of PAHs. While low-molecular-weight PAHs may degrade more rapidly, high-molecular-weight PAHs may accumulate in the atmosphere, potentially increasing respiratory exposure risks. Conclusions Atmospheric PAHs in Chinese cities show a clear north – south gradient, with higher concentrations in northern regions due to winter coal combustion and limited pollutant dispersion under low temperatures. Despite lower socioeconomic development in Northwest China compared with eastern coastal cities, OCP residues in soil and air are comparable, while PAH levels are often higher, likely reflecting regional differences in historical usage and pollutant behavior under arid conditions. POP sources in arid regions of Northwest China exhibit strong spatial heterogeneity. HCHs mainly originate from historical residues and lindane use, whereas DDTs are associated with industrial inputs and dicofol-related sources. PAHs primarily derive from biomass, coal, petroleum combustion, and traffic emissions, with additional influence from long-range atmospheric transport in desert petroleum areas such as Tazhong. Overall, POP sources follow a pattern dominated by local emissions with supplementary external inputs. Health risk assessments indicate generally low POP-related risks across most arid areas, although localized concerns remain. Potential carcinogenic risks from PAHs are observed in suburban Urumqi crops and in desert-adjacent cities, where elevated TSP-bound PAHs lead to lifetime inhalation cancer risks exceeding acceptable limits. Recommendations and perspectives Atmospheric and soil POP levels in most arid cities of China remain within safe limits, with elevated risks confined to areas near industrial or agricultural emission sources. However, crops in arid regions may present potential exposure risks and warrant closer monitoring. Airborne POP concentrations can increase in winter due to additional emission sources and reduced atmospheric dispersion. During dust and sandstorm events, personal protective measures are recommended, as PM₁₀ and PM_2.5 can carry substantial pollutant loads. Given limited regulation of emerging contaminants in China, priority pollutants should be identified for targeted regional control. Authorities should optimize functional zoning by separating residential areas from pollution sources, strengthen industrial management, promote green production, and enhance regulation of pesticide manufacture and use.