Research on Power Plant Ash Impact on the Quality of Soil in Kostolac and Gacko Coal Basins

Abstract

Increased concentrations of heavy metals in ash can adversely affect the microbiological and pedogenetic processes in soil. The aim of this paper is to determine the impact of ash from unburned coal generated in the Kostolac and Gacko coal basins on the quality of soil in the surrounding environment. The investigation included the surface soil layer that was sampled and tested during 2016 and 2017. A total of 30 samples of Kostolac soil and 9 samples of Gacko soil were analyzed for the content of 8 heavy metals: Cu, Pb, Cd, Zn, Hg, As, Cr and Ni. The analyses were carried out by inductively coupled plasma mass spectrometry (ICPMS) technique according to the EPA 6020A method and the following conclusions were made: Kostolac coal ash affects the quality of the surrounding soil in terms of Ni, Cu and Cr as evidenced by the moderately strong correlation of the Ni-Cu pair (k = 0.71), as well as the Cu-Cr pair (k = 0.73) and strong correlation of the Ni-Cr pair (k = 0.82), while the high recorded concentration of Pb, Hg, As and Zn is attributed to other sources of pollution, such as the traffic network and intensive farming activities, and in some cases, its impact is only local. All recorded concentrations of heavy metals are within the remediation values. The effect of ash on soil contamination in the surroundings of the Gacko coal basin is limited to Ni and Cd, with a strong correlation coefficient of this pair (k = 0.82). The recorded overrun of maximum allowed concentration of Cr is evidenced in only 2 samples, and in terms of this element the contamination of the Gacko soil can be considered to be local. It is concluded that prevailing winds play a part in soil pollution. Cluster analysis showed that Ni, Cr and Zn have very similar values in analyzed soil samples from both basins, while a cluster composed of only Hg, in the case of Gacko, indicates lower contamination with Hg compared to the other heavy metals.

Ecological Risk of Toxic Metal Contamination in Soil around Coal Mine and Thermal Power Plant

“…The pollution of the biosphere of toxic metals became dramatic at the beginning of the industrial revolution and urbanization, since when it poses a major problem around the world [2][3][4], especially in developing countries [5]. In recent decades, environmental pollution by toxic metals has been a significant global problem with a characteristic cumulative effect and risk for the ecosystem [6,7]. Toxic metals are natural components of Earth curst, but in many ecosystems, the concentration of some metals has reached toxic levels due to the effects of anthropogenic activity.…”

“…Toxic metals in soils near factories generally enter the soil from industrial activities. Pollutants are ubiquitous in the environment, especially in industrialized zones [6][7][8][9] and can be strongly accumulated in soil [10]. The term toxic metals usually mean the so-called heavy metals.…”

“…Toxic metals, such as Pb, As, Cd and Ni, are emitted from anthropogenic sources [17], under the effect of industrial activities, soils were moderately contaminated with Cd, uncontaminated to moderately contaminated with As and Zn, and uncontaminated with Cr, Cu, V, and Pb [18]. Mining and thermal power plants are significant sources of soil toxic metal pollution [1,6,[19][20][21]. Areas near thermal power plant, mining areas and urban areas are high-risk areas for soil toxic metal pollution.…”

“…Soil Cd, Zn, As, and Pb contamination was attributed to high-temperature coal combustion [18]. The combustion of coal in thermopower plants release various pollutants, which once released into the air reach the land where they are deposited [6]. Toxic metals Cd, Pb, Hg, Cr and As are known for their plant toxicity.…”

“…Toxic metals enter the soil through the diffusion or leaching of dust, residual tailings, slag, and waste rock generated by mining, stacking, and transportation activities [1]. The remediation of soil polluted by toxic metals is very expensive and complex, it is essential to develop and establish a pollution prevention system [6].…”