Environmental risks from impacts of industrial solid wastes applied on agricultural land in China: a comprehensive overview.

With the rapid development of industrialization in China, more and more industrial solid wastes (ISWs) are generated in industrial production processes. Under the pressure for safe disposals or utilization of ISWs as resources, and the demand for soil pollution remediation in China, there have been attempts to incorporate ISWs into agricultural land as soil amendments, while the environmental impacts of ISWs applied on agricultural land have aroused great concerns. This paper presents a comprehensive overview regarding the environmental risks from impacts of 7 types of ISWs (including blast furnace slag, steel slag, magnesium slag, coal-fired flue gas desulfurization gypsum, phosphogypsum, calcium carbide slag, and ammonia-soda residue) applied on agricultural land. The study reviews relevant literatures by searching and browsing scientific databases, providing an analysis of data concerning the environmental impacts of these ISWs applied on agricultural land in China, mainly focusing on soil eco-environment and food safety affected by some pollutants from the ISWs, aiming at providing an evaluation on the environmental risks from impacts of the ISWs associated with land application. Many studies in China revealed that several pollutants (such as Hg, Cd, As, Pb, Cr, Ni, Cu, and Zn) in those ISWs-affected areas were accumulated in soils, far beyond the risk screening values for soil contamination of agricultural land in China (GB 15618-2018). Also, some pollutants (such as Hg, Cd, As, Pb, Cr, Cu, Zn, and F) were detected in crops (including cereals, vegetables, and feeds) in those ISWs-affected soils, even exceeding the limits of the National Food Safety Standard-Maximum Levels of Contaminants in Foods in China (GB 2762-2022), thus posing the potential risks of secondary pollutions from the ISWs to soils and food chains. The same concerns about environmental risks from the impacts of ISWs applied on agricultural land have also been raised in the world. As China's leadership in the production of ISWs, the greater challenge for reducing the environmental impacts from ISWs is faced by China than other countries. To strengthen the management of ISWs in China, a series of environmental policies, regulations, and standards for soil pollution prevention and control have been successively promulgated, imposing strict restrictions on the disposals of ISWs in farmlands. Researches have suggested that those ISWs lacking pre-treatment for removal of harmful elements should not be allowed for being used as soil amendments in farmlands, to prevent pollutants from entering the food chains and harming to human health. Instead, recycling these ISWs as partial substitutes for building materials in cement production could offer an eco-friendly and energy-saving alternative for their disposals and utilization.