Abstract
The rehabilitation of the post-mining landscape is one of the intractable bottlenecks faced by the mining industry. Though plant restoration has been regarded as an efficient way, its application is often restricted by the physicochemical properties of the soil, i.e., macronutrient deficiencies. In this work, a novel plant restoration method was proposed that employs maize straw and ultrasonically pre-treated coal fly ash (UCFA) for soil amelioration. Seed germination experiments were performed to investigate the effect of maize straw leachates (MSLs) on the growth of maize, alfalfa, and soybean. Then, the influence of MSLs and UCFA on the physiological attributes, chlorophyll, and trace element concentrations of maize was studied by plant growth experiments. Our results show that: (i) the MSLs concentration had a significant effect on the plant growth and the optimum concentration was 20%; (ii) considering the physiological attributes of maize plants, MSLs and UCFA benefited its growth in most cases. The UCFA proportion should be less than 20 v.% for optimum performance; (iii) the mixture of MSLs and UCFA could generally increase the chlorophyll and decrease trace element concentrations; and (iv) the optimum proportion was found to be soil:UCFA:MSLs = 70:20:10 and soil:UCFA:MSLs = 60:20:20, which achieved satisfactory performance during engineering applications.
Highlights
Open-pit coal mining has long been criticized for its potential to cause severe long-term land degradation
Plant growth experiments were conducted to study the influence of maize straw leachates (MSLs) and ultrasonically pre-treated coal fly ash (UCFA)
Based on the above results, the following conclusions can be drawn: 1. The MSLs concentration had a significant influence on the physiological attributes and chlorophyll of maize, alfalfa, and soybean
Summary
Open-pit coal mining has long been criticized for its potential to cause severe long-term land degradation. A large amount of mine spoil will be dumped to the adjacent land, resulting in stockpiles, the formation of spoil overburden dumps [1]. With greater public awareness of these dumps on the environment and public health, i.e., soil contamination, the rehabilitation of overburden dumps has been one of the most important issues encountered by the mining industry [2]. The main objective of such rehabilitations is to restore a disturbed ecosystem so it is similar to the pre-existing ecosystem, both in structure and function, or maintain a self-sustaining ecosystem similar to the adjacent unmined land [3,4,5]. Direct plant restoration on spoil overburden dumps is often infeasible due to the physicochemical properties of soil, including but not limited to unsuitable pH, macronutrient deficiencies, low waterholding capacity, and potential trace metal contamination [13,14]. Many studies have been conducted to investigate the feasibility of different materials for soil amelioration, among which coal fly ash (CFA) and crop straw have attracted much interest from both academia and industry [16]
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