Microbial community and biogeochemical characteristics in reclaimed soils at PT Bukit Asam coal mine, South Sumatra, Indonesia

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Kyle Bryce Corcoran (Creator)
Western Carolina University (WCU )
Web Site: http://library.wcu.edu/
Jerry R. Miller and John P. Gannon

Abstract: Organic soil amendments such as compost, wood chips, and sewage sludge have been reported to influence soil microbial composition, improve soil quality, and increase nutrient concentrations in surface runoff. A potentially negative consequence of adding compost to soils is that it may increase the solubility of metals in surface waters and groundwater. This study investigated the effects of compost age and compost application type on metal (e.g. Al, Fe, Mn, Ni, Pb, Zn) concentrations in subsurface waters at reclaimed areas of the PT Bukit Asam Coal Mine, located near Tanjung Enim, South Sumatra, Indonesia. The mine relies heavily on the use of compost to improve soil productivity of reclaimed and reforested areas. The compost is aged for fourteen-weeks and mainly composed of materials from oil palms (Elaeis guineensis) and, to a lesser degree, organic municipal solid waste from the local community. In an effort to determine the most effective method for applying compost to reclaimed soil, compost was applied in a five-centimeter-thick layer spread over the reclaimed soil surface, or mixed with the soil placed in the hole where vegetation was planted. Soil bacterial DNA was extracted on site to characterize the microbial communities within the various aged research plots. All 16S rDNA sequences generated from the DNA using PCR were related to Gram negative-staining bacteria. RDP Classifier assigned four of the sequences to the phylum Proteobacteria and one to Acidobacteria. These heterotrophic bacteria likely play a role in organic matter turnover and utilize specific major and trace metals for metabolic processes over time, which is consistent with lower values observed in the older plot. In addition, subsurface water metal concentrations, total metal concentrations in soil, grain size distribution, and total percent carbon were compared between study plots of varying ages (3 months to 120 months) and compost treatments. Reclaimed soil without the addition of compost was also examined as a control. Total metal concentrations in soil were all within global background values and below soil contaminant levels. The geochemical data for total metal concentrations in surface and subsurface soil samples showed no sign of metal depletion from the surface or accumulation at depth, which indicates limited metal mobility through the soil profile. Field observations show that minimal metal mobility may have occurred through soil fractures. These data are consistent with the low metal concentrations observed in subsurface waters. Limited metal mobility to shallow subsurface waters is likely to result, in part, from the low permeability of the soils, which was primarily composed of silt and clay. Our results suggest that neither the type of compost application nor age of application had a significant effect on microbial diversity, or metal mobility within the soils, thereby limiting the potential contamination of subsurface waters within the PTBA reforested reclamation areas.

Additional Information

Language: English
Date: 2018
Hydrologic sciences, Soil sciences, Microbiology
Compost -- Indonesia -- Sumatera Selatan
Organic wastes -- Indonesia -- Sumatera Selatan
Soils -- Heavy metal content -- Indonesia -- Sumatera Selatan
Soil pollution
Soils -- Leaching
Groundwater -- Pollution
Soil biochemistry

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