Microbial Community Diversity Dynamics in Acid Mine Drainage and Acid Mine Drainage-Polluted Soils: Implication on Mining Water Irrigation Agricultural Sustainability

Abstract

Environmental degradation related to mining-generated acid mine drainage (AMD) is a major global concern, contaminating surface and groundwater sources, including agricultural land. In the last two decades, many developing countries are expanding agricultural productivity in mine-impacted soils to meet food demand for their rapidly growing population. Further, the practice of AMD water (treated or untreated) irrigated agriculture is on the increase, particularly in water-stressed nations around the world. For sustainable agricultural production systems, optimal microbial diversity, and functioning is critical for soil health and plant productivity. Thus, this review presents up-to-date knowledge on the microbial structure and functional dynamics of AMD habitats and AMD-impacted agricultural soils. The long-term effects of AMD water such as soil acidification, heavy metals (HM), iron and sulfate pollution, greatly reduces microbial biomass, richness, and diversity, impairing soil health plant growth and productivity, and impacts food safety negatively. Despite these drawbacks, AMD-impacted habitats are unique ecological niches for novel acidophilic, HM, and sulfate-adapted microbial phylotypes that might be beneficial to optimal plant growth and productivity and bioremediation of polluted agricultural soils. This review has also highlighted the impact active and passive treatment technologies on AMD microbial diversity, further extending the discussion on the interrelated microbial diversity, and beneficial functions such as metal bioremediation, acidity neutralization, symbiotic rhizomicrobiome assembly, and plant growth promotion, sulfates/iron reduction, and biogeochemical N and C recycling under AMD-impacted environment. The significance of sulfur-reducing bacteria (SRB), iron-oxidizing bacteria (FeOB), and plant growth promoting rhizobacteria (PGPRs) as key players in many passive and active systems dedicated to bioremediation and microbe-assisted phytoremediation is also elucidated and discussed. Finally, new perspectives on the need for future studies, integrating meta-omics and process engineering on AMD-impacted microbiomes, key to designing and optimizing of robust active and passive bioremediation of AMD-water before application to agricultural production is proposed.

Unlocking water potential in drylands: Quicklime and fly ash enhance soil microbiome structure, ecological networks and function in acid mine drainage water-irrigated agriculture

“…These findings are further supported by Raletsana et al [ 37 ], who noted 46% reduced potato yield with AMD water irrigation, while Choudhry et al [ 38 ] reported a 62% decrease rice yield in rice due to elevated acidity, EC, Fe, Mn, SO 4 2− , and diminished availability of P, K, and Zn in AMD-contaminated paddy field. Hence, the phytotoxic effects of AMD acidity and the contamination of agricultural soil and crops, and potential transfer of toxic HM into the food chain, underscore concerns over untreated AMD water agriculture [ 6 ].…”

“…The Witwatersrand Basin in South Africa, with a long history of gold mining, is one of the regions affected by AMD, discharging about 202 million L/day AMD wastewater [ 4 ], This water resource has been suggested as an important potential solution to the region's freshwater shortage [ 4 , 5 ], but poses a threat to ecological systems, agricultural land, and human health due to its high acidity and nonbiodegradable heavy metals (HM) contamination. Therefore, it must be treated to a quality suitable for use in irrigated agriculture and non-potable applications [ 6 ].…”

“…Due to increasing water scarcity, the use of untreated and treated AMD water for irrigation is becoming more common in agriculture, but sustained use requires consideration of the impacts of these waters on both crop production and maintenance of good soil physical properties and health. Particularly, phytotoxicity-related AMD acidity and HM contamination of agricultural soil and crops, and HM entering the food chain through food crop uptake, remain key concerns related to reuse of AMD water for irrigated agriculture [ 6 ].…”

“…Optimal soil microbiome diversity is vital for sustainable agriculture, as it is crucial for plant growth, soil health, and fertility. Studies have shown that the soil microbiome plays a significant role in AMD-contaminated environments, involving essential processes such as pH neutralization, metal bioremediation, plant growth promotion, sulfates/iron reduction, and biogeochemical N and C recycling [ 6 ]. However, there is limited information is available on how the structure and functions of soil microbiome are affected in AMD water-irrigated agriculture.…”

Characterization and risk assessment of soil around waste rock heaps affected by acid rock drainage in an abandoned pyrite mining area

“…On one hand, the minerals are usually accompanied by various potentially toxic trace metals (PTEs) such as Pb, Cd, Cr, Mn, Ni, Cu, Tl, and Zn (Liu et al, 2019). On the other hand, the high acidity increases the bioavailability of PTEs and can affect microbial activity, community structure, and nutrient production (Baek et al, 2021;Munyai et al, 2021). For example, toxic metals including Cd, Cr, and Pb, and excessive amounts of metals Cu, Mn, Ni, and Zn, retard the growth of vegetables and have chronic effects on humans including kidney damage, cardiovascular failure, anaemia, and cancer (Edelstein and Ben-Hur, 2018).…”