Investigating the level of arsenic (As) and nickel (Ni) contamination caused by the emission of dust from bauxite crushers

Industrial development and human activities intensify the propagation of various contaminants in the environment. Heavy metals from various sources, such as industrial and agricultural activities, cause serious environmental hazards for the ecosystem. Environmental dusts are sometimes manmade, due to the activity of industries and human units, known as industrial dusts. The purpose of this study was to investigate the effect of industrial dust emitted from the Bauxite crasher located in the upstream of Jajarm Alumina Factory on the level of soil pollution. The study is focused on two heavy metals: Arsenic (As) and Nickel (Ni).

In this research, with regard to the wind roses of the area, first the direction of the dominant and erosive winds was determined. Then, two transects were considered: a transect in the direction of erosive wind (transect A) with 3 km length, and a transect in the direction of the dominant wind (transect B) with 5 km length. Samples from the soil surface (at a depth of 0-2 cm) were taken on these transects at regular intervals from the source of dust, i.e. Bauxite crusher. In total, 46 soil samples were collected. The concentration of Arsenic and Nickel in the soil samples was determined by the method of Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES), after acid digestion by chemical means in the laboratory. Finally, the indicators of land accumulation, pollution, comprehensive pollution and enrichment were used to determine the contamination level. Significance of increase in Arsenic and Nickel concentrations, as well as the other contamination coefficients were analyzed in SPSS software using ANOVA and T-test.

The Earth's accumulation index in the direction of erosive wind for Arsenic, at a distance of 200 to 250 m from the source, showed a medium to severe contamination. For nickel, from the source of dust production to 350 m distance, the area was identified unpolluted to medium contaminated. For Arsenic, in the dominant wind direction at a distance of 150 m and 250 to 450 m, moderate to severe pollution was determined. For Nickel, up to 900 m from the source of dusts, the area was identified unpolluted to medium contaminated.For Arsenic and Nickel, The pollution index in the direction of erosive wind up to 450 meters from the source of dust production shows a high to medium pollution level. And show medium and low to end transect, for Arsenic and Nickel. By this indicator, the high pollution levels in the dominant wind direction were determined for Arsenic up to 1200 m from the source of dusts, and medium pollution levels of the index of pollution was determined for Nickel, from the source of dust production up to 500 m far apart. And show medium and low to end transect, for Arsenic and Nickel. Comprehensive index of pollution in the case of erosive and prevailing winds for Arsenic and Nickel showed high and medium pollution levels, respectively. Enrichment factor in the direction of erosive wind indicated medium concentration of Arsenic at 350 and 400 m from Bauxite crusher, and a low enrichment for Nickel at all points. In the dominant wind direction, a medium enrichment factor for Arsenic was observed up to 250 m from bauxite crusher, while the level of Nickel enrichment at all locations was low. Finally, the statistical analysis justified the significance of the measured concentrations of Arsenic and Nickel, as well as the other coefficients of pollution level in the direction of prevailing and erosive winds.