Abstract:In order to better understand the role of coal gangue in potential environmental and ecological risks, the leaching behavior of trace elements from coal gangue has been investigated in an open-cast coal mine, Inner Mongolia, China. Four comparative column leaching experiments were conducted to investigate the impacts of leaching time, pH values and sample amount on the leaching behavior of trace elements. Enrichment factors (EF), maximum leached amount (L am ), maximum leachability (L rm ), effects range low (ERL) and effects range median (ERM) were employed to evaluate potential environmental and ecological hazards resulting from the leaching behavior of environment-sensitive trace elements from coal gangue. Leaching time and sample amount display important effects on trace element concentrations, leached amounts and leachability. The pH values exhibit a weak influence on the leaching behavior of the selected trace elements (e.g., As, V, Cr, Co, Ni, Cu, Zn, Se, Cd, Sn, Pb and Hg). The coal gangue are enriched in As, Co, Se and Pb and, in particular, show higher environmental pollution levels of As and Se (EF > 2). L am values suggest that all of the elements investigated do not show potential risk to soils and vegetation, but have a high hazard risk for ground water. Elements including Ni, As, Cr and Zn are inclined to show high or moderate biological toxicity.

Abstract:Coal is the most important fossil energy used in China. The environmental impact of trace elements released in coal combustion has become one of the hottest issues in recent years. Based on a software named CiteSpace, and social network analysis (SNA), a bibliometric analysis of research into trace elements in coal and ash field during 1971-2017 is presented with the information of authors, countries, institutions, journals, hot issues and research trends in the present study. (6) The enrichment origin and modes of occurrence of trace elements are the mainstream research related to trace elements in coal and ash. The environmental problems caused by coal combustion have promoted the development of trace elements in coal research, and human health is getting more and more popular in recent years. The study findings provide a better understanding of features of trace elements in coal and ash research, which could be taken as a reference for future studies in this field.

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China has issued eight mandatory national standards so far to regulate the water efficiency of household products. The State Administration for Market Regulation performs national spot checks yearly on products qualities, which includes water efficiency, meantime it required market regulation bureaucracies of regional levels to strengthen inspection of energy and water efficiency labels from 2019. However, those two levels of inspection neither focus on water efficiency standards nor cover all eight categories of products. Furthermore, there is still space to improve in term of supervision effectiveness, efficiency and database management. For those reasons, this article aims to clarify the deficiencies and propose corresponding advice on the supervision system.

Faced with increasingly severe pressure on water resources, virtual water and virtual water trade theory provide a feasible solution to improve global water use efficiency for agricultural product and to alleviate the pressure on water resources in water-scarce countries or regions. However, virtual water strategy has not been considered in domestic inter-regional agriculture products trade of China. In this research, we will create scenarios, from two aspects of economy and the allocation and utilization of water resources, to study the impact of virtual water strategy on domestic inter-regional agriculture products trade of China. Two kinds of scenarios will be created. One kind of scenarios does not consider the virtual water strategy, which only consider the economic revenue - net social revenue maximization scenario. The other kind of scenarios considers the virtual water strategy - water resource balance scenario. And we will research the impact of virtual water strategy will be made on domestic interregional agriculture productions trade of China. The result shows that virtual water strategy could make advantage impact on the allocation and utilization of water resources by domestic inter-regional agriculture products trade of China. But domestic inter-regional agricultural products virtual water trade of China considered the virtual water strategy would cause great negative impact on net social revenue.