Long-term Effects of Rock Type on Appalachian Coal Mine Soil Properties.

Rock-derived overburden material is used as a topsoil substitute for reclamation of Appalachian coal mines. We evaluated five mixtures ( = 4 each) of sandstone (SS) and siltstone (SiS) overburden as topsoil substitutes for 25+ years to quantify changes in mine soil properties. The study area was planted only to tall fescue [ (Schreb.)], but over 50 herbaceous species invaded over time. Standing biomass was highest in early years (5.2-9.3 Mg ha in 1983) and was strongly affected by rock type (SS > SiS), declined significantly by 1989 (1.5-2.4 Mg ha), and then increased again (2×) by 2008. However, there was no long-term rock type effect on standing biomass. Rock fragments and texture differed after 26 yr, with fewer rock fragments in the SS-dominated mixtures (53 vs. 77% in SiS) and lower sand and higher clay in the SiS-dominated mixtures. Soil pH initially ranged from 5.45 (SS) to 7.45 (SiS), dropped for several years, increased in all SiS mixes, and then slowly declined again to 5.65 (SS) to 6.46 (SiS) over the final 15 yr. Total N, organic matter, and cation exchange capacity increased with time, and extractable P decreased. Chemical weathering was most apparent initially, but physical weathering of rock fragments and changes in texture continued throughout the study period. Influences of original rock mixtures remained apparent after 25+ yr in both physical and chemical properties of these mine soils, which remained much coarser than local native soils but were higher in pH, exchangeable cations, and extractable P.

Long-term impacts on macroinvertebrates downstream of reclaimed mountaintop mining valley fills in Central Appalachia.

Recent studies have documented adverse effects to biological communities downstream of mountaintop coal mining and valley fills (VF), but few data exist on the longevity of these impacts. We sampled 15 headwater streams with VFs reclaimed 11-33 years prior to 2011 and sampled seven local reference sites that had no VFs. We collected chemical, habitat, and benthic macroinvertebrate data in April 2011; additional chemical samples were collected in September 2011. To assess ecological condition, we compared VF and reference abiotic and biotic data using: (1) ordination to detect multivariate differences, (2) benthic indices (a multimetric index and an observed/expected predictive model) calibrated to state reference conditions to detect impairment, and (3) correlation and regression analysis to detect relationships between biotic and abiotic data. Although VF sites had good instream habitat, nearly 90 % of these streams exhibited biological impairment. VF sites with higher index scores were co-located near unaffected tributaries; we suggest that these tributaries were sources of sensitive taxa as drifting colonists. There were clear losses of expected taxa across most VF sites and two functional feeding groups (% scrapers and %shredders) were significantly altered. Percent VF and forested area were related to biological quality but varied more than individual ions and specific conductance. Within the subset of VF sites, other descriptors (e.g., VF age, site distance from VF, the presence of impoundments, % forest) had no detectable relationships with biological condition. Although these VFs were constructed pursuant to permits and regulatory programs that have as their stated goals that (1) mined land be reclaimed and restored to its original use or a use of higher value, and (2) mining does not cause or contribute to violations of water quality standards, we found sustained ecological damage in headwaters streams draining VFs long after reclamation was completed.