全球气候变化对健康的影响已然成为最受关注的环境和公共健康问题之一。气候变化，直接或间接地影响持久性有机污染物（Persistent organic pollutants, POPs) 在环境中的分布、迁移转化和效应等，进而对相关POPs多途径暴露的人体健康产生影响，然而有关整个影响路径的研究较少，气候变化影响POPs多介质环境归趋及相关人体健康的影响程度尚不清楚。本文选取中国大陆为研究区域，选取多环芳烃（Polycyclic aromatic hydrocarbons, PAHs）为代表性POPs物质，构建了多介质环境模型、生物富集模型以及人体健康风险评价模型三者疏松耦合的大尺度、高精度的模型体系，量化了0.5°×0.5°空间分辨率内基准年和未来两种气候变化情景代表性浓度路径（Representative concentration pathway, RCP）4.5和RCP8.5下温度升高1.5-4 °C时16种PAHs在不同环境介质中的浓度水平，识别了呼吸、皮肤接触及经口摄入多种人体暴露PAHs的途径，进一步量化了多途径及累积的人体健康风险，进而探究未来气候变化对中国PAHs多介质归趋及相关人体健康的影响程度，揭示了影响的区域差异和不同增温幅度之间的差异，并提出了未来PAHs减排目标。主要研究结果如下：

（1）基准年PAHs的多介质分配和浓度空间分布

基准年PAHs由大气向其他介质中扩散。水与沉积物之间的交换通量与最为显著。土壤是中国PAHs的主要汇。PAHs各组分在不同环境介质中的质量分布随着分子量的不同而不同。除空气中外，高分子量（High-molecular-weight, HMW）PAHs的比例比低分子量（Low-molecular-weight, LMW）PAHs更显著。各环境介质中PAHs总浓度的空间分布模式由PAHs排放量决定，呈现出中国北方>中国南方>中国西北和青藏高原地区的基本规律。其中，排放量最高的“2+26”城市所在省市各环境介质中PAHs总浓度最高，低排放的中国西北和青藏高原地区各环境介质中PAHs总浓度较低，主要受大气传输影响。

（2）未来气候变化对PAHs多介质环境归趋的影响

未来气候变化情景下，中国大陆不同环境介质（大气、淡水水体、淡水沉积物、土壤及植被）中16种PAHs总浓度减少了0.1-20.4%，主要原因是气候变暖，温度升高，促进了PAHs在不同环境介质中的降解代谢过程。大气PAHs总浓度的变化百分比相比于其他介质低1-2个数量级；由空气向其他介质传输的净通量减少了0-24%。PAHs将从其他介质向大气迁移。大气中LMW PAHs浓度减少0-3.9%，HMW PAHs浓度增加0-18.5%，二者相反的变化趋势主要由大气降解速率差异导致，HMW PAHs在大气中降解慢，温度对其促进作用小于对向大气分配的促进作用。其他介质中LMW PAHs和HMW PAHs浓度均降低，且LMW PAHs浓度的减少占主导作用。在未来气候变化背景下，土壤仍然是中国PAHs的主要汇。相较于基准年，分配给大气和植被的PAHs比例增加，分配到淡水、淡水沉积物和土壤的比例将减少。此外，PAHs浓度绝对变化的空间分布主要由PAHs排放控制，PAHs浓度相对变化的空间分布主要受气候因素变化的控制。

（3）基准年PAHs人体暴露结构及健康风险水平

基准年不同途径暴露于PAHs的人体健康风险值呈现经口摄入>呼吸摄入>皮肤接触的基本规律，其中经口摄入暴露途径所占比例约为99.6%（中位值），其次是呼吸暴露途径（0.3%），最后是皮肤接触暴露途径（0.04%）。30-60岁人群环境暴露行为一般多于其他年龄段人群，表明该年龄段人群的健康风险最大。三种途径各自的健康风险和多途径累积暴露的总体健康风险的空间分布情况类似，与排放、浓度分布情况相一致，呈现出中国北方>中国南方>中国西北和青藏高原地区的基本规律。

（4）未来气候变化对PAHs人体暴露结构及健康风险的影响

相较于基准年，未来气候变化情景下，人体PAHs主要暴露途径的结构没有改变，依旧保持经口摄入>呼吸摄入>皮肤接触的规律。然而，呼吸暴露风险所占比例增加（30.5%）,皮肤接触暴露和经口摄入暴露风险所占比例减少（分别为0.7%和0.1%）。随着温度升高，多途径暴露的累积总体健康风险减少1.6-22.2%；气候变暖，更多PAHs向大气中迁移，大气中HMW PAHs浓度增加，呼吸暴露风险增加0.2-5.8%；经口摄入和皮肤接触暴露的风险有所降低，两种暴露途径的风险降低幅度相当。青藏高原和中国西北地区PAHs人体暴露及健康影响对气候变化的响应强于其他地区。气候变化背景下，全国72-73%区域仍具有潜在的癌症风险，36-37%区域具有较高的癌症风险。为将全国健康风险降低到安全水平，PAHs的总排放量需要减少到2014年排放量的87%。灵敏度分析结果表明温度对多途径累积总风险的影响最大，解释了71.2%的变异性。

Global climate change and consequent health effects are the most concerning environmental and public health issues. Climate change can directly or indirectly affect the environmental fate of persistent organic pollutants (POPs), and further produce an effect on human exposure and the related human health risks. However, few studies have explored how climate change drives multi-media fate of POPs, multi-pathway human exposure of POPs, and associated health risks. The extent of the impact is not clear. In this study, we coupled a well verified spatially explicit high-resolution multimedia Sino Evaluative Simplebox-MAMI (SESAMe) v3.4 model, a bioconcentration model, and a human health risk assessment model on a continental scale, to predict multi-media concentrations of polycyclic aromatic hydrocarbons (PAHs) and the resulted human intake and health risks for the investigation for Chinese mainland. we comprehensively evaluated the multi-media PAH environmental concentrations and human health risks induced by multi-pathway exposure to PAHs under two different climate change scenarios (Representative Concentration Pathway (RCP) 4.5 and RCP8.5) with 1.5-4 °C warming targets across the Chinese mainland with a spatial resolution of 0.5°, by comparing with the base year 2009. We deeply discussed the drive mechanism of environmental processes to PAH multi-pathway exposure and associated health risks under different climate change scenarios across different areas in China. We finally made a policy proposal on emission reduction targets to reduce cancer risk in the future. The main results are as flows:

(1) Multi-media partitioning and spatial distribution of PAH concentrations in the base year

PAHs mainly transport diffusively to other media in the base year. The exchange flux between water and sediment is the most significant. Soil is the primary sink of PAHs in China. The mass distribution of PAH components in different environmental media varies with the molecular weight. Except in the air, the proportion of high-molecular-weight (HMW) PAHs is higher than that of low-molecular-weight (LMW) PAHs in all the compartments. The predicted geographic distribution pattern is generally similar for each compartment on the continental scale and mainly dominated by PAH emissions. The basic law is: North China > South China > Northwest China and Qinghai-Tibet Plateau. Especially, the concentration is generally predicted to be the highest for all compartments and concentrated in the cities and provinces where "2 + 26" cities are located with the highest emissions. Northwest China and Qinghai-Tibet Plateau with the lowest PAH emissions are mainly affected by the surrounding atmospheric transport, except for some areas with local PAH emissions.

(2) Effects of future climate change on multi-media environmental fate of PAHs

The total concentrations of 16 PAHs would decrease in all environmental compartments (air, freshwater, freshwater sediment, soil and vegetation) by 0.1-20.4%. This is mainly caused by accelerated degradation of PAHs in environment, with the degradation rate of 16 PAHs rising under 1.5-4 °C warming. The percentage of concentration change in the air would be 1-2 orders of magnitude lower than that in other environmental media. In addition, the net flux of air-to-surface processes would decrease by 0-24%. PAHs would tend to migrate to the air, especially under the RCP8.5 scenario. In the atmosphere, the concentrations of HMW PAHs increase (0-18.5%) while those of LMW PAHs decrease (0-3.9%). The opposite trends of concentration change of HMW and LMW PAHs in the atmosphere might be due to the fact that the degradation rate of HMW PAHs in the air is lower than LMW PAHs, and the promotion effect of climate warming on HMW PAHs degradation in the atmosphere is not as strong as that on its transport from other media to the atmosphere. In other media, the concentrations of LMW and HMW PAHs would decrease, and the decrease of LMW PAHs would gradually dominate. The soil would still be the primary sink of PAHs in China under future climate change. The proportion of PAHs allocated to the atmosphere and vegetation would increase, and the proportion to water, soil, and sediment would decrease with temperature increase from 1.5 to 4 °C. The spatial distribution of changes in PAH absolute concentration was consistent with that of PAH emission, while for the change percentage of PAH concentration, its spatial distribution is controlled by climate change.

(3) Human exposure and health risks of PAHs in the base year

The basic law of human health risks exposed to PAHs through different pathways in the base year is oral intake > respiratory intake > dermal contact. The most essential exposure pathway of PAHs was oral intake, contributing more than 99.6% (median) of total intake, followed by respiratory exposure (0.3%), and finally dermal contact exposure (0.04%). People aged 30-60 have the greatest PAH exposure risks, because they have more environmental exposure behaviors than that of other age groups. The health risks induced by individual exposure pathways and cumulative health risks induced by all three exposure pathways exhibited a similar spatial pattern with PAH concentrations and emissions. The basic law of spatial pattern is: North China > South China > Northwest China and Qinghai-Tibet Plateau.

(4) Effects of future climate change on human exposure and health risks of PAHs

Considering the future climate change, the structure of the main exposure pathways remains unchanged compared to the base year: oral intake > respiratory intake > dermal contact. The proportion of respiratory exposure increased (30.5%), and the proportion of dermal contact exposure and oral exposure decreased (0.7% and 0.1%, respectively). As a result, the overall human health risks exposed by multi-pathway exposure would reduce by 1.6-22.2%, while the risk induced by respiratory intake would increase by 0.2-5.8% due to the increase of PAHs in the air under the background of future climate change, especially HMW PAHs. The risk induced by oral intake and dermal contact intake would decrease, and the reduction was similar. Regarding the spatial differences of risk relative changes, the response of health impacts to PAHs exposure in Qinghai-Tibet Plateau and Northwest China is stronger than that in other regions. Under future climate change, the multi-pathway health risks would still be higher than 1.00×10^-6 in 72-73% of grids over China under future climate change, with potential cancer risk, and higher than  1.00×10^-4 in 36-37% of grids over China under future climate change, with high cancer risk. To achieve a safe level nationwide, PAH emissions need to be cut by 87% of year 2014. The results of sensitivity analysis showed that temperature had the greatest impact on the overall multi-pathway human health risks, explaining 71.2% variability.