基于多区域投入产出模型的国际贸易隐含水体氮排放转移研究

MRIO model based study on water nitrogen pollution transfer embodied in international trade

经济全球化进程的加快是贸易隐含污染物排放转移的主要驱动因素,近年来氮足迹与全球氮循环问题日益引发关注,水体氮是氮的主要存在形式,主要来自于种植业、畜禽养殖业、氮肥生产以及城市生活污水排放。本研究利用全球污染排放数据库,基于2015年的全球投入产出模型,从污染转移总量以及贸易流污染排放强度两方面计算了国际贸易对全球水体中的氮排放格局的影响。主要结论:(1)水体氮排放量的转移方向与大小与区域距离的远近、农业资源的丰富程度以及经济发达程度有关。水体氮排放转移量较大的贸易流大部分为经济较发达的区域向经济次发达区域的污染转移,一些农业资源禀赋程度相似、区域距离较远的区域污染转移量一般较小。一个国家向经济发展程度比自己低的区域出口的产品流隐含的污染强度低,向比自己经济发展程度高的区域出口的产品污染强度高。建议通过农机具援助、技术培训等方式,加快对非洲、亚洲等区域的农业技术转移和扩散,帮助农业生产欠发达地区提高农业生产力和管理水平,降低欠发达地区向发达地区出口的贸易流中的污染强度。(2)2015年,中国贸易隐含的水体氮污染净进口量为16万t,占到全球水体氮进口的2. 72%,谷物进口大幅增加是产生水体氮净进口的重要原因。大幅增加的进口以及过高的粮食库存不仅给世界带来资源环境压力,也进一步加剧了本国的资源环境压力,因此不仅应从产量上关注粮食安全,还要从生态安全的角度调整粮食供给结构、种植结构和进出口结构,最大限度的降低因农业生产带来的资源环境压力。

The acceleration of economic globalization is the main driving factor of transferring pollutant emissions between nations embodied in international trade.In the recent years,Nitrogen footprint and global nitrogen cycle issue have drawn attention increasingly in recent years.Nitrogen in water bodies,mainly from planting industry,livestock and poultry farming,nitrogen fertilizer production,as well as urban domestic sewage discharge,is the main existing form of nitrogen.This study uses the global pollutant emission databases and 2015 global input-output model to calculate the impact of international trade on nitrogen emission pattern in global water bodies based on considering the total amount of pollutant transfer and pollutant emission intensity of trade flows.The main conclusions are:① the transfer direction and amount of water nitrogen emission are related to the distances between regions,the degree of abundance of agricultural resource,and economic development level.There are always large amount of water nitrogen emission transferring from developed economy to developing economy in their bilateral trade activities whereas small amount of transfers are of some areas with similar endowments of agricultural resources and long distances.The pollutant intensity embedded in a country’s exported products to regions with lower degrees of economic development is lower than to regions with higher degrees of economic development.It is recommended that through applying alleviations such as agricultural machinery assistance and technical training to accelerate the transfer and spread of agricultural technology in Africa,Asia and other regions,thus helping increase agricultural production productivity in underdeveloped areas and reducing the pollutant intensity embedded in trade flows from underdeveloped areas to developed areas.② In 2015,the net import of water nitrogen pollution implied by China’s trade was 160,000 tons,accounting for 2.72 % of the global water body nitrogen imports.The main reason of producing a net import of water nitrogen is due to the sharp increase in cereal imports.These sharp increase in imports,together with high food storage as well as high pollution intensity embedded in trades,not only results in more pressure on world’s resources and environment,but also futher exacerbate the pressure on national resources and environment.Therefore,it is necessary not only to pay attention to food security from the perspective of production,but also to adjust the grain supply structure,planting structure and imports/exports structure from the perspective of ecological security to minimize the pressure on resources and environment due to agricultural production.Thus,instead of paying attention to food security from the angle of production,it is suggested that the supply-demand structure,crop planting structure,and trade structure should be adjusted from the angle of ecological security.