Joshy George

Soil quality index for evaluation of reclaimed coal mine spoil.

Success in the remediation of mine spoil depends largely on the selection of appropriate tree species. The impacts of remediation on mine soil quality cannot be sufficiently assessed by individual soil properties. However, combination of soil properties into an integrated soil quality index provides a more holistic status of reclamation potentials of tree species. Remediation potentials of four tree species (Acacia auriculiformis, Cassia siamea, Dalbergia sissoo, and Leucaena leucocephala) were studied on reclaimed coal mine overburden dumps of Jharia coalfield, Dhanbad, India. Soil samples were collected under the canopies of the tree species. Comparative studies on the properties of soils in the reclaimed and the reference sites showed improvements in soil quality parameters of the reclaimed site: coarse fraction (-20.4%), bulk density (-12.8%), water holding capacity (+0.92%), pH (+25.4%), EC (+2.9%), cation exchange capacity (+46.6%), organic carbon (+91.5%), N (+60.6%), P (+113%), K (+19.9%), Ca (+49.6%), Mg (+12.2%), Na (+19.6%), S (+46.7%), total polycyclic aromatic hydrocarbons (-71.4%), dehydrogenase activity (+197%), and microbial biomass carbon (+115%). Principal component analysis (PCA) was used to identify key mine soil quality indicators to develop a soil quality index (SQI). Selected indicators include: coarse fraction, pH, EC, soil organic carbon, P, Ca, S, and dehydrogenase activity. The indicator values were converted into a unitless score (0-1.00) and integrated into SQI. The calculated SQI was significantly (P<0.001) correlated with tree biomass and canopy cover. Reclaimed site has 52-93% higher SQI compared to the reference site. Higher SQI values were obtained for sites reclaimed with D.sissoo (+93.1%) and C.siamea (+86.4%).

Bioavailability and health risk of some potentially toxic elements (Cd, Cu, Pb and Zn) in street dust of Asansol, India

Street dust samples were collected from five different types of land use patterns (busy traffic zone, urban residential area, national highways, industrial area and sensitive area) in a medium sized industrial city Asansol, India. The samples were fractionated into ≤53µm and analyzed for potential toxic elements (PTEs) viz. Zn, Cd, Pb and Cu. The mean total concentration of Zn, Cd, Pb and Cu in the urban street dust samples were 192, 0.75, 110 and 132mgkg-1 respectively. Chemical speciation was performed for PTEs to evaluate the bio-available fractions. Cu was mostly associated with organic matter phase while Zn, Pb and Cd with residual phase. Mean mobility factor (MF) for heavy metals in Asansol was Zn (54.6%)>Pb (49.1%)>Cu (25.3%)>Cd (22.7%). Geo-chemical indices such as Enrichment Factor (EF), geo-accumulation index (Igeo) and contamination Factor (CF) were in the order of Pb>Cd>Zn>Cu. Cluster analysis was done to understand the similarities among the sites. The risks of all metals was calculated with mobile fraction, which indicated actual risk due to PTEs was less (HI<1).

Impacts of opencast coal mine and mine fire on the trace elements’ content of the surrounding soil vis-à-vis human health risk

Coal from its excavation, processing, and utilization creates environmental problems and health hazards. In these processes, the mobilization of potential organic and heavy metal contaminants affects the quality of soil and health of the inhabitants. Soil samples were collected from the nearby areas of an opencast coal mine (OCM) and a coal fire affected area (CFA) located in Jharia coalfield of Dhanbad, India. The control site was an abandoned land approximately 15 km away from the sources of contamination. These samples were analyzed for trace elements including Cr, V, Co, Ni, Cu, Zn, Ga, Rb, Zr, Ba, Th, and U. The soils of OCM were enriched with Cr and Ni and this is attributed to the mining activities in view of the absence of other sources of pollutants. In case of CFA, the soils were enriched with Cr, V, Ni, and Zn. However, the concentrations of Cr, Ni, and Zn in both the soils were well below the USEPA soil screening levels for human health risk assessment. The levels of Co and V exceeded the soil screening limits. Human exposure risks were evaluated for Co and V. The total intake of V concentration exceeded the EPAs reference dose, which may pose adverse health risks.

Evaluation of the co-application of fly ash and sewage sludge on soil biological and biochemical quality

Disposal of sewage sludge (SS) and fly ash (FA) is a multifaceted problem, which can affect environmental quality. FA has the potential to stabilize SS by reducing metal availability and making the SS suitable for application in the agricultural sector. An experiment was performed to evaluate soil biological quality changes with the combined amendment of SS and FA (fluidized bed combustion ash (FBCA) and lignite fly ash (LFA)). SS was amended with 0, 10, 30, 50 and 100%, (w/w) of FA, and then the FA–SS mixtures were incubated with red soil at 1:1 (v/v). Soil quality parameters such as pH, electrical conductivity, N, soil enzyme activities such as dehydrogenase (DHA), urease (URE), and catalase (CAT), and microbial biomass carbon (MBC) were evaluated at 20, 30, and 60 days of incubation. pH and EC increased with FA–SS dose; however, N decreased. DHA and URE were found to be increased with 10% LFA amendment; thereafter it decreased. However, URE increased up to 30% of FBCA. CAT and MBC increased with both FA amendments, even up to addition of 50% FA. Bioavailable Zn, Cu, and Co contents were decreased by the addition of FA. Principal component analysis showed that pH is the most influential factor. MBC appears to be a sensitive soil indicator for the effects that result from the addition of FA–SS. Phytotoxicity studies with Zea mays showed optimum performance at 30% FA. Addition of 10–30% FBCA or LFA to SS has a positive advantage on soil biological quality.

Potentially toxic elements in lignite and its combustion residues from a power plant

The presence of potentially toxic elements in lignite and coal is a matter of global concern during energy extraction from them. Accordingly, Barsingsar lignite from Rajasthan (India), a newly identified and currently exploited commercial source of energy, was evaluated for the presence of these elements and their fate during its combustion. Mobility of these elements in Barsingsar lignite and its ashes from a power plant (Bikaner-Nagaur region of Thar Desert, India) is presented in this paper. Kaolinite, quartz, and gypsum are the main minerals in lignite. Both the fly ash and bottom ash of lignite belong to class-F with SiO2 > Al2O3 > CaO > MgO. Both the ashes contain quartz, mullite, anhydrite, and albite. As, In, and Sr have higher concentration in the feed than the ashes. Compared to the feed lignite, Ba, Co, U, Cu, Cd, and Ni are enriched (10–5 times) in fly ash and Co, Pb, Li, Ga, Cd, and U in bottom ash (9–5 times). Earth crust–normalization pattern showed enrichment of Ga, U, B, Ag, Cd, and Se in the lignite; Li, Ba, Ga, B, Cu, Ag, Cd, Hg, Pb, and Se, in fly ash; and Li, Sr, Ga, U, B, Cu, Ag, Cd, Pb, and Se in bottom ash. Hg, Ag, Zn, Ni, Ba, and Se are possibly associated with pyrite. Leaching test by toxicity characteristic leaching procedure (TCLP) showed that except B all the elements are within the safe limits prescribed by Indian Standards.

The Impact of Fly Ash Amendment on Soil Carbon

Soils play an important role in carbon cycling. An important approach to terrestrial carbon sequestration is to make use of currently underutilized and waste/degraded lands. The addition of fly ash can ameliorate the adverse conditions of wastelands through a variety of mechanisms, besides helping in stabilization of the soil carbon. Carbon mineralization and humification studies were carried out with soil, fly ash, and their mixtures. Organic monomers included for the humification reactions were resorcinol, p-hydroxybenzoic acid, L-glycine, and L-serine. Results showed that the humification pattern was higher for Associate Cement Companies (0.154 λ485) and Khaparkheda (0.119 λ485) fly ashes, than soil (0.110 λ485). In the carbon mineralization experiment, the soil carbon stabilization enzyme peroxidase activity was higher at soil amended with fly ash (0.052 μM/g/h) than soil alone (0.013 μM/g/h). The dissolved organic carbon was almost two times lower in fly ash amended soil, which revealed the adsorption of carbon in fly ash. The adsorption of soluble organic compounds on the solid surfaces is one of the mechanisms of fixing of soil organic carbon. The cumulative CO2 liberation due to plant litter addition was not affected by fly ash. To conclude, fly ash is abundantly available and is considered as a waste in many thermal power plants, which could be sustainably utilized in the agriculture and forestry sectors, both under arable and waste degraded land for enhancing terrestrial carbon sequestration, besides increasing the plant growth and yield.

Impact of coal industries on the quality of Damodar river water

Increasing demand for water in domestic, agricultural, and industrial sectors necessitates exploitation of water either in the form of groundwater or from natural resources. To safeguard the long-term sustainability of water resources and their utilization, the quality of water has to be periodically monitored and determined for various characteristics, especially when the sources are polluted, such as Damodar river. Central Institute of Mining and Fuel Research (CIMFR), Dhanbad, is carrying out research work on coal and its utilization and associated environmental concerns. The blood stream of life for the whole Jharia Coalfield is none other than the river Damodar. CIMFRs campus also depends exclusively on river Damodar for meeting its demand of drinking water. This study is a general survey toward the characteristics of Damodar river water, with special emphasis on the pollutant parameters, and evaluation of the treatment process being carried out at the institute for potability. Damodar river water is indeed affected by the disposal of the wastes without any pre-treatment by different coal-based industries established in its basin. The quantity of dissolved and suspended solids, total hardness, chemical oxygen demand, and coliform bacterial count are higher in Damodar water due to the disposal of the waste/effluents from coal-washing plants, coke ovens, cement, and other industries, but well within the permissible limit which is probably attributable to the high-carrying capacity of the river. The river is still not that much affected as it is usually apprehended, and it can be well utilized for potable and domestic purposes after simple treatment.

Phosphorus Removal Using Lignite Fly Ash

Phosphorus (P) release to surface waters leads to serious pollution. The development of technology for P removal offers the opportunity for abatement of environmental hazards and recycling. Fly ash is widely available and a cheap adsorbent; its alkaline properties make it interesting for precipitation of phosphates. An attempt was made to study the P removal ability of lignite fly ash. In order to determine the phosphate removal capacity of fly ash and the effect of adsorbent quantity (5 and 10 g per 100 ml), temperature (28 and 50°C), retention time (5 and 30 min) on P removal, sorption studies were conducted using phosphate solutions containing 20, 50, 100, 150, and 200 mg/l P. The results showed that the lignite fly ash was able to remove even 100% of 20 mg/l P at 10 g adsorbent with 30 min retention time at 28°C. The P removal capacity decreased with increase in P concentration; the removal was 86.51% at 200 mg/l P. The adsorbent quantity significantly influenced the P removal; the average removal was 94.81% at 5 g and 97.5% at 10 g. The Langmuir adsorption maximum was the highest for 5 g of fly ash–30 min equilibrium at 28°C (40.98 mg/kg). The adsorption maxima decreased with increase in temperature, however, the factor related to bonding energy has increased at 50°C. Altogether the study revealed that the lignite fly ash could be successfully used for instantaneous P removal at ambient conditions; however, other parameters like solid-liquid ratio, maximum carrying capacity, etc. need to be yet optimized.