Multistatistical approaches for environmental geochemical assessment of pollutants in soils of Gadoon Amazai Industrial Estate, Pakistan

The current study was carried out in Gadoon Amazai industrial estate and surrounding areas in order to investigate environmental pollution resulted from various industries. The industries flush their effluents in the surrounding areas without treatment, which can contribute toxic elements and compounds to the soil and also to groundwater of nearby areas. The toxic metals have high potential ecological risk to surrounding environment. A continuous field survey was conducted to find out flow of industrial effluent in surrounding area. For determining major and toxic metals in soil, a random sampling technique was followed to collect representative samples. A total of 45 samples were collected with 25 soil samples from target areas and 20 samples from the reference areas. For the toxic and heavy metals, 1 g powder soils (-200 mesh size) was treated with hydrofluoric acid (10 ml), aqua regia (20 ml), and HCl (20 ml). For the major elements, 0.5 g samples was treated with hydrofluoric acid (10 ml) and perchloric acid (4 and 2 ml with 2-h interval). All these soil samples were analyzed for 13 major and toxic metals using Perkin Elmer atomic absorption spectrophotometer (AAS-700) equipped with graphite furnace (GF). The results showed that the mean concentrations (mg/kg) of toxic, heavy, and major elements in target area are 301.6, 8.8, 152.3, 58.8, 144.7, 359.4, 32.5, 1097, 2508, 786.5, 2572, 4088, and 689.8 for Cr, Cd, Pb, Ni, Cu, Zn, Co, Fe, Mn, Mg, Na, Ca, and K, respectively. The mean concentration (mg/kg) for toxic and major elements in the reference area are 93.6, 6.1, 35.5, 55.9, 59.1, 116.4, 24.1, 644.3, 1112, 549.0, 1275, 2364, and 995.2 for Cr, Cd, Pb, Ni, Cu, Zn, Co, Fe, Mn, Mg, Na, Ca, and K, respectively. Several approaches such as pollution load index, ecological risk index, geo-accumulation index, enrichment factor, etc. were applied in order to infer anthropogenic contributions. This study indicated that majority of the toxic and major elements contribute to soil pollution, but the toxic metals have high influence on the environment as compared to major elements. Therefore, industrial and commercial activities in the area are the main cause of higher potential ecological risk, as compared to the reference areas. There is strong need for remediation and mitigation measures in the study area, which could help to minimize the environmental pollution produced by the industrial estate.