Chemical, physical‐temporal and spatial changes in 25‐year‐old mine soils in Southeast Ohio

Abstract

Reclaimed surface coal mines afford an opportunity to study initial pedogenic processes. This study sought to determine pedogenic processes active in a topsoiled* surface mine over 25 years. Soils were taken at 108 points from three grids in 1979 (1 year) and 2004 (25 years post-reclamation) across a 20 ha watershed. The upper darkened portion of the replaced soil (^A1, ca. 0-5 cm), lower portion of the replaced soil (^A2, ca. 5-15 cm), and spoil (^2C) were sampled. Exchangeable Ca 2+ increased from 4.3 cmol c kg À1 in 1979 to 8.2 cmol c kg À1 in 2004, and exchangeable Mg 2+ increased from 2.5 to 3.3 cmol c kg À1 . Soil organic carbon (SOC) increased from 0.59% to 4.05% providing evidence for humification and cycling of basic cations.SOC increases and structural development decreased bulk densities from 1.70 to 0.99 g cm À3 in the ^A1 and 1.70 to 1.24 g cm À3 in the ^A2. pH decreased in all horizons. In ^2C horizons, total sulfur decreased from 0.39% to 0.13% and electrical conductivity 3.34 dS m À1 to 1.01 dS m À1 , indicating probable pyrite oxidation and salt leaching. Soils classified as Anthroportic/Anthrodensic Udorthents, as three representative pedons lacked cambic horizons. Mine soil variograms indicated higher spatial dependency in ^A1 and ^A2 horizons in 2004 than 1979 (decreasing nugget: sill ratios), whereas ^2C horizons had lower spatial dependencies in 2004. This suggests that surface horizons are more influenced by soil forming factors than spoil, which is more influenced by 'random' conditions of reclamation and not in equilibrium.

Effects of recultivation on soil organic carbon sequestration in abandoned coal mining sites: a meta-analysis

“…For near-neutral pH soils, they recommend less intensive management practices that increase beneficial microbial growth efficiency 78 . While mine soils normally have a low pH 13,98,99 , they have also been known to reflect the other extreme of strongly alkaline conditions 13 . The advice provided by Malik et al 78 for acidic soils involves intensifying plant production and prioritising the management of abiotic C-accumulating factors such as acidity and wetness 78 .…”

Small‐scale spatial variability of Technosol properties in a chronosequence of reclamation of dredged‐sediment landfills

“…Studies that have investigated spatial relationships of Technosol properties have shown stronger spatial dependency of selected chemical properties (i.e., pH, organic carbon) after a few years of Technosol formation on areas affected by mine tailings (Burgos et al, 2006). Demyan & Smeck (2021) also note that overall spatial dependency of mine soil properties increases over time in surface horizons, which indicates that spatial variability is more driven by soil forming processes than by initial reclamation activities.…”

“…Quantifying the extent of spatial variability is particularly important to better, classify, map, and manage mining-derived residues as they may exhibit high variability even in short distances of <100 m (Haering et al, 2005). A spatial and temporal characterization of the substrate properties that show spatial patterns and their evolution cannot be conducted using nonspatial statistical methods (Demyan & Smeck, 2021). A previous assessment of a 12-year chronosequence of Technosol forming on dredged-sediment deposits left by alluvial gold mining showed drastic changes among the Technosol properties in sites of different ages as well as high within-site variability of soil properties (Betancur-Corredor et al, 2020).…”