Technosols designed for rehabilitation of mining activities using mine spoils and biosolids. Ion mobility and correlations using percolation columns

Abstract

The restoration technologies in areas degraded by extractive activities are more efficient under the use of their own spoils. Reducing deficiencies in physical properties, organic matter, and nutrients with a contribution of treated sewage sludge is proposed. This experiment was based on a controlled study using columns. The work was done with two limestone quarry spoils, both very rich in calcite. Two biosolids doses were undertaken (30,000 and 90,000 kg/ha of sewage sludge) in addition to a different quarry spoils used as substrates. The water contribution was provided by a device simulating short duration rain. The leached water was collected 24 hours after the last application. Nitrate, ammonium, phosphate, sulfate, and chloride ions were determined, as well as the pH and electrical conductivity. The electrical conductivity limit value is <1000 µS/cm. These values will be met from the fourth irrigation application onward, while the values up to that point were far superior. Significant nitrate concentrations appeared that may pose an environmental contamination risk. A comparison between the concentrations of the chemical elements obtained in the leachates from our experiment and the established limit values for water of the third quality group has been performed. The electrical conductivity correlated well with the cations, with the exception of potassium. For sulfates, significant correlations were obtained with the Mg 2+ , Ca 2+ , and K + cations. The chlorides showed excellent correlation with the sodium.

Sewage sludge as an organic amendment for quarry restoration: Effects on soil and vegetation

“…However, nitrogen leaching, if it occurs, should take place mainly in the first 4 months after sludge application due to the high mineralization rates of organic‐N from sludge. After this, leaching risk should decrease quickly due to nitrate absorption by roots of the growing plants, reducing the risk of aquifer eutrophication (Jordán et al, ; Tarrasón et al, ). Moreover, it has to be taken into account that this risk is relatively low due to the small surface restored (<2 ha in a quarry per year) and because sludge is applied only once, compared to agricultural applications where sludge is applied recurrently at the same plot.…”

Mid‐term effects on ecosystem services of quarry restoration with Technosols under Mediterranean conditions: 10‐year impacts on soil organic carbon and vegetation development

“…Although nitrogen leaching is plausible with the sludge treatment, it would mainly take place during the first 4 months due to the high mineralization rates of organic N from sludge (Carabassa et al ). After this period, leaching should decrease quickly due to reduced sludge decomposition rates and the enhanced nitrate absorption by the growing vegetation (Tarrasón et al ; Jordán et al ). As SOC becomes stabilized over time in sludge‐amended Technosols (Ojeda et al ), N stabilization in organic forms is also expected, as shown by the balanced C:N ratios observed.…”

Edaphic Filters and Plant Colonization in a Mine Revegetated with Sewage Sludge

“…Sanitary issues that limit the use of sewage sludge in agriculture are not impediments for using it in mines (Corrêa, 2009). Increase of organic matter content, nutrient concentrations, and microbial biomass (Domene et al, 2010;Gardner et al, 2010;Torri et al, 2014;Wijesekara et al, 2016), improvement of physical attributes (De Maria et al, 2007;Jordán et al, 2017), and spontaneous revegetation of surfaces (Andrés et al, 2007;Borges et al, 2009;Silva et al 2013) follow the incorporation of organic residues into mining substrates.…”