Variation of Nutrients and Salinity For Applying Fly Ash and Wood Vinegar in Coal Gangue Substrate

Abstract

Coal gangue and fly ash are major industrial solid wastes containing some nutrients associated with organic or mineral matter. Vegetation restoration depends on high-quality soil in mining sites. Exploring the effects of wood vinegar (WV) irrigation and fly ash addition on the variation in chemical properties of the coal gangue substrate can provide a theoretical basis and data support for the reconstruction of mine soils and resource utilization of mine solid wastes. The indoor soil incubation experiment was conducted by adding fly ash at rates of 0, 10%, 20% and 50% to a coal gangue substrate mixed with coal gangue and raw soil. We analyzed the nutrients and salinity of the mixture of coal gangue substrate and fly ash (CGSFA) after irrigating distilled water (DW) and WV. The results showed that the addition of fly ash decreased the pH of the CGSFA mixture under DW irrigation, and WV irrigation increased the pH of the CGSFA mixture compared with DW irrigation. The addition of fly ash could increase the contents of dissolved organic carbon (DOC), available phosphorus (AP) and available potassium (AK) and decrease the contents of total organic carbon (TOC) and total nitrogen (TN) of the coal gangue substrate. Compared with DW irrigation, WV irrigation increased the contents of TOC, DOC, active organic carbon (AOC) and AP of the CGSFA mixture by 19.3%, 931.1%, 228.1% and 15.6% and decreased the contents of TN and AK by 10.6% and 35.1%, respectively. In addition, the addition of fly ash increased the contents of K + , Ca 2+ and SO4 2and decreased the Na + content in the coal gangue substrate. The irrigation of WV increased the contents of Mg 2+ , HCO3 -, Cl and SO4 2of the CGSFA mixture and reduced the contents of K + and Na + . Overall, fly ash addition and WV irrigation can improve the nutrients and salinity of the mixture of the coal gangue substrate. Considering the accumulation of HCO3-, Cl and SO4 2-, it is recommended to choose 10% to 20% fly ash addition to coal gangue substrate and irrigation with WV for the reconstruction of mine soils.