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		西安重度以上污染天气PM2.5重金属污染特征与健康风险
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			Pollution characteristics and health risk of heavy metals in PM2.5 in severely polluted weather in Xi'an, China
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| 图1. 重度以上污染天气PM2.5质量浓度和9种重金属总浓度 | 
| Fig.1. PM2.5 mass concentration and total concentration of heavy metal in severely polluted weather | 
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