Long-term effects of aided phytostabilisation on microbial communities of metal-contaminated mine soil

Abstract

Aided phytostabilisation uses metal-tolerant plants, together with organic or inorganic amendments, to reduce metal bioavailability in soil while improving soil quality. The long-term effects of the following organic amendments were examined as part of an aided phytostabilisation field study in an abandoned Pb/Zn mining area: cow slurry, sheep manure and paper mill sludge mixed with poultry manure. In the mining area, two heavily contaminated vegetated sites, showing different levels of soil metal contamination (LESS and MORE contaminated site), were selected for this study. Five years after amendment application, metal bioavailability (CaCl extractability) along with a variety of indicators of soil microbial activity, biomass and diversity were analysed. Paper mill sludge mixed with poultry manure treatment resulted in the highest reduction of Cd, Pb and Zn bioavailability, as well as in stimulation of soil microbial activity and diversity, especially at the LESS contaminated site. In contrast, cow slurry was the least successful treatment. Our results emphasise the importance of the (i) long-term monitoring of soil quality at sites subjected to aided phytostabilisation and (ii) selection of the most efficient amendments and plants in terms of both reduction of metal bioavailability and improvement of soil quality.

Chemical Composition, Antioxidant and Anti-Inflammatory Activities of Clary Sage and Coriander Essential Oils Produced on Polluted and Amended Soils-Phytomanagement Approach

“…Based on the use of plants and their associated microorganisms, phytotechnologies are considered as environmental-friendly, cost-effective, and benefit from a high public acceptance [ 1 , 3 , 4 ]. One of the main strategies, referred to as phytostabilisation, resides in the immobilisation of the pollutants in the plant rhizosphere to reduce their bioavailability and alleviate wind and water erosion phenomena [ 5 , 6 ]. However, increased concentrations of TE may impair plant growth and weaken the success of the method [ 1 , 6 ].…”

Potential Benefits and Risks for Soil Health Derived From the Use of Organic Amendments in Agriculture

“…The beneficial or adverse effects of any given agricultural practice on soil health are usually evaluated and monitored through a wide array of indicators, which include physical (e.g., structure, bulk density, porosity, aggregate stability, water holding capacity), chemical (e.g., contents of plant macro-and micronutrients, OM, pH, cation exchange capacity), and biological (e.g., enzyme activities, respiration, potentially mineralizable nitrogen, microbial biomass C and nitrogen, microbial functional and structural diversity, diversity of macro-and mesofauna) soil properties. The latter group (biological properties) and, in particular, soil microbial indicators gained much attention lately, owing to their sensitivity, fast response, integrative characteristic, and ecological relevance [66][67][68][69]. Indeed, soil microorganisms, which comprise a major fraction of the soil total living biomass, play a key role in soil functioning and the delivery of crucial ecosystem services [70][71][72].…”

How Valuable Are Organic Amendments as Tools for the Phytomanagement of Degraded Soils? The Knowns, Known Unknowns, and Unknowns

“…Meanwhile, soil microbial properties (i.e., biomass, activity, functional, and structural diversity) have attracted great interest as quick, integrative, and sensitive indicators of soil perturbations (Epelde et al, 2010;Burges et al, 2015;Garaiyurrebaso et al, 2017) and can serve to identify the magnitude of the improvements brought about by management interventions (Aparna et al, 2014). These microbial indicators provide more direct insight into soil health/quality than traditional physical and chemical indicators alone (Ge et al, 2013).…”

“…Over last years, phytoremediation technologies such as "aided phytostabilization" have been successfully implemented as a phytomanagement strategy, succeeding mitigate the environmental impact of metal-contaminated soils and displaying great potential to be applied to extended areas (Venegas et al, 2015). Aided phytostabilization is defined as an environmentally friendly in situ phytoremediation strategy based on the combination of metal-tolerant plants (phytostabilization) and organic or inorganic amendments (chemical stabilization; Garaiyurrebaso et al, 2017), which simultaneously reduce soil metal mobility/bioavailability, thereby reducing leaching and their transfer through trophic web, improving soils microbial properties and facilitating plant establishment (revegetation; Gómez-Sagasti et al, 2012;Clemente et al, 2015). In the field of restoration of mining impacted soils and metalliferous mine tailings, the application of aided phytostabilization programs are particularly encouraged (Galende et al, 2014a;Pardo et al, 2014;Madejón et al, 2018), in order to avoid the burdensome resource investments that involved soil remediation (Brown and Chaney, 2016).…”

“…The metal stabilization and immobilization processes, including adsorption, precipitation and/or complexation (Sharma and Nagpal, 2017), depend upon the particular metal and soil type involved, degree of humification of the organic matter, content of metals and salts and the effects of organic matter on the redox potential and soil pH (Clemente et al, 2005;Pérez-Esteban et al, 2014). However, although metals are immobilized within soil and become less bioavailable, the amended sites require long-term and regular monitoring and runoff control measures to ensure that the optimal stabilizing conditions of metals remain unchanged (Basta et al, 2016;Garaiyurrebaso et al, 2017;Khalid et al, 2017).…”