| Lead（Pb）,as a typical heavy metal and a kind of hazardous air pollutants（HAPs）,has attracted worldwide attention due to its adverse effects on the ecological environment and human health.Pb has been listed as the long-term concern goal of the Convention on long-distance Transboundary Transport of Air pollutants（CLRTAP）by the United Nations Economic Commission for Europe（UNECE）.Particularly,Pb and its compounds were classified as group 2A carcinogens,that is,possible carcinogens to human beings,by the International Agency for Research on Cancer（IARC）.Since the reform and opening up,a great amount of heavy metals have been emitted from various sources into the atmosphere,water and soil environment,as a consequence,a number of poisoning accidents associated with toxic heavy metals have occurred throughout China.The heavy metals are particularly of widespread concern in the world due to their adverse effect and high toxicity on ecosystem and human health.Pb,a one of the ten criteria air pollutants,has categorized into the National Ambient Air Quality Standard（GB3095-2012）,in which Pb is the unique heavy metal listed in the air quality standard in China.Although some researches have reported that the atmospheric emissions of heavy metals exhibited an obviously decline trend since 2012,it cannot be ignored that the serious harm of heavy metals to human health and ecosystem in term of their significant characteristics such as non-degradation and accumulation as well as persistence in the environment.More than 80% of atmospheric Pb emissions in China are siginificantly related to human industrial production activities and the demand driven by inter-regional trade.Inter-regional trade not only contains the exchange of goods and services,but also implies the pollutant transfers embodied in interprovincial trade flows.China,as the most developing country in the world,has a vast territory and mass population.There are differences among regions for the energy mineral resources,and the level of industrial technology and economic development,as well as environmental policy.In the 21 st century,China’s government has sequentially launched a series of programs,such as western region development strategy,west-east gas transmission project,as well as west-east power transmission project.The programs and strategy promoted the local industrial level and economic development in the western regions of China,as a result,yielding large amount of pollution emissions and serious harm to the local ecological environment and residents’ health while the major resource and energy products are indispensable consumed by the eastern area of China.Thus creat the regional“environmental inequality” between eastern and western China.Therefore,it is significantly important to evaluate and quantify regional environmental inequality（REI）index between the Pb emission and economic benefit transfer embodied in interprovincial trade to eliminate or reduce regional environmental inequality.In this study,we firstly established atmospheric Pb emission inventory by emission factor method based on activity data of sectors in 30 provinces of China in 2002,2012 and 2017,including the energy consumption data,the steel and non-ferrous metal production,and other activity data.Secondly,we calculated the production-based and consumption-based atmospheric Pb emissions and transfers embodied in interprovincial trade in China using multi-regional input-output（MRIO）model.And we also analyzed the Pb emissions and GDP transfer driven by inter-provincial trade of China.Due to the unfairness between Pb emission and GDP flow in bilateral trade,the regional environmental inequality driven by inter-provincial trade in China was evaluated.Finally,we adopted an atmospheric environmental fate model to simulate the atmospheric Pb concentration and deposition flux based on two simulated scenarios（Trade and Non-trade scenario）in China for 2017,and we estimated the impacts of goods and services trade on the atmospheric Pb concentration,dry deposition,as well as health risk due to atmospheric Pb exposure.The major results of this study are as follows:（1）Temporal trend of atmospheric Pb emission inventory in China: The atmospheric Pb emissions revealed an increasing trend from 8886 tons of Pb in 2002 to14331 tons in 2012,with an annual growth rate of about 6.13%.Since 2012,Pb emissions showed a downward trend,and Pb emission in 2017 has decreased by 37.6%compared with 2012.The areas with higher Pb emissions are mainly located in the central and eastern of China,such as Shanxi and central Shaanxi,Beijing-Tianjin-Hebei,the Yangtze River Delta,the Pearl River Delta,the central Shandong,the northern Henan,the central of Liaoning and Sichuan Basin.In terms of emission source contribution,the major contributions of Pb emission in China are from industrial coalfired sources,power plant coal-fired sources,iron and steel smelting and non-ferrous metal smelting,accounting for about 63.7% to 76.7%.（2）The spatio-temporal distribution of atmospheric Pb emission intensity in China:The Pb emission intensity in China showed a downward trend from 2002 to 2017,with an average annual decline rate of about 11.3%.From the view of spatial region,the Pb emission intensity of the underdeveloped provinces,located in the central and western regions of China,is significantly higher than that in the developed eastern coastal areas of China.The ferrous and non-ferrous metals smelting and processing sector represented the highest Pb emission intensity,followed by the electric power supply department,cement glass and ceramic production,petroleum processing and coking.（3）Production-based and consumption-based atmospheric Pb emissions in China:The areas with the largest production-based Pb emissions,located in the central and northwest regions of China,which accounted for about 46.4% of total Pb emissions.By comparison,the developed eastern coastal areas,such as Beijing-Tianjin,the Yangtze River Delta,and the southeast coastal areas,accounted for less than 15.5% of the total.For the consumption-based Pb emission,the provinces with higher Pb emissions could be found in the central and eastern coastal areas of China.For example,Pb emissions induced by the final demand of underdeveloped regions,such as northwest,southwest and central China,are mainly contributed by local emissions（57.3%-73.9%）in 2012 and 2017.Pb emissions induced by the final demand of developed regions,such as Beijing-Tianjin,the Yangtze River Delta,as well as the southern coastal areas of China are mainly contributed by the relatively underdeveloped regions（47.8%-66.7%）,such as the northwest,southwest,central and northern China.（4）Net Pb emission and GDP transfer embodied in interprovincial trade in China:The well-developed and densely populated eastern coastal areas showed virtual Pb net outflow in China,while the underdeveloped areas located in western China revealed virtual Pb net inflow.The GDP transfer showed a reverse trend in which the welldeveloped eastern coastal areas of China are the main GDP net inflow areas,while the western underdeveloped provinces showed GDP net outflow.（5）Regional environmental inequality（REI）due to Pb transfer embodied in interprovincial trade in China: We divided the 435 bilateral trade relations of China into two categories by the REI index in this study in 2017.The first group of bilateral trade relations（accounting for about 41.8%）,such as Henan-Zhejiang（REI=2.27）and Shaanxi-Jiangsu（REI=1.89）,is characterized by the fact that the less developed provinces suffer from not only the Pb emissions induced by consumption needs of developed regions,but also economic loss in bilateral trade.The second group of bilateral trade relations（58.2%）,such as Shanxi-Beijing（REI=0.53）and Inner Mongolia-Xinjiang（REI=0.71）,is characterized by the results that less developed provinces suffer from the Pb emissions induced by the final demand of developed regions and gain economic compensation in bilateral trade.（6）Impact of inter-provincial trade on Pb environmental fate and health risk in China: Inter-provincial trade subject to the demand and consumption of inter-provincial trade had much larger contribution to the magnitude and distribution of atmospheric Pb concentration than that from atmospheric transport,especially for two areas far away from each other.The atmospheric concentration and dry deposition of Pb in central and eastern China were reduced owing to inter-provincial trade but increasing in the western region of China.Overall,inter-provincial trade led to a 21.5% decrease of atmospheric Pb dry deposition flux across China in 2017.The cancer cases of atmospheric Pb exposure increased in sparsely populated and less-developed western provinces,while it reduced in densely populated and well-developed eastern provinces in China due to interprovincial trade.Generally,interprovincial trade led to a 311 reduction in the number of additional cancer cases exposured to atmospheric Pb in China,with a decrease of 9.5%. |
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