Superposition Effects of Zinc Smelting Atmospheric Deposition on Soil Heavy Metal Pollution Under Geochemical Anomaly

Abstract

Guizhou Province is covered by a large area of carbonate rocks where, with a higher background of heavy metals under the geochemical anomaly, more than 3.6 × 105 ha of heavy metal–contaminated soil in the northwest area is related to historical indigenous zinc smelting. To explore the superposition effect of industrial source atmospheric deposition on soil, two watersheds were selected for study: 1) Maoshui reservoir watershed (MS), where there is a zinc smelting plant, and 2) Haishe lake watershed (HS), which was the control. We collected atmospheric depositions and soil for 3 years and analyzed Cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn) content. The results show that the heavy metals in the atmospheric deposition of the pollution watershed in MS were much higher than those in the control site, HS. The deposition fluxes of Cd, Pb, Cr, Ni, and Zn in MS were 27.8, 602, 145, 43.9, and 2,225 mg·m−2·a−1, respectively, and were 1.37–2.01 times higher than in HS. Soil heavy metals in MS were 1.01–5.69 times higher than in HS. The elevated concentrations were found focused from northeast to southwest around the plant but was distributed uniformly in HS. The average concentration of Cd, Pb, and Zn in the soil was 6.54, 67.4, and 264 mg·kg−1, respectively, in HS, which represents a high geochemical background even without pollution. After 13 years of deposition by prediction, the contribution of the atmospheric deposition on the soil in the zinc-smelting area was lowest, at 5.10%, for Ni, and highest, at 17.9%, for Cd. Principal component analysis of atmospheric deposition and soil heavy metals reflected that the pollution sources in MS were more diversification than those in HS. Zinc smelting atmospheric deposition showed superposition effects on the accumulation of heavy metals in soil under the geochemical anomaly in this region.

Study on Safe Usage of Agricultural Land in Typical Karst Areas Based on Cd in Soil and Maize: A Case Study of Northwestern Guizhou, China

“…Researchers generally agree that the weathering soil formation process of mineral-bearing rock systems is the main cause of high Cd accumulation in karst soils [60,61]. The soil-forming parent material of geochemically high geological background soils mainly originates from carbonate rocks, which are widely present in Guizhou [62]. This is consistent with the causes of high soil Cd accumulation in many carbonate rock areas [63].…”

Soil-to-Wheat Transfer of Heavy Metals Depending on the Distance from the Industrial Zone

“…Heavy metals characterized by similar values of the main components and positioned close to each other with their vectors are influenced by similar factors, such as similar sources or soil properties [53,57,61,82,92,93]. In our study, the first two principal compo-nents explained the largest source of variation, where positive PCA 1 values were found for the heavy metals Cr, Cd, Zn, and Cu, which can indicate a common source of contamination.…”

Source Identification and Superposition Effect of Heavy Metals (HMs) in Agricultural Soils at a High Geological Background Area of Karst: A Case Study in a Typical Watershed

“…In addition, atmospheric deposition was a significant source for Cd, Pb, Cr and Zn. Because of the presence of a zinc smelting plant and smelting slag in this area, contributions of atmospheric deposition for Cd, Pb, Zn and Cr were relatively high [ 17 ]. Zinc smelter primarily polluted surrounding soil through atmospheric deposition, in which HMs mainly came from flue gas emissions and ground dust.…”

“…The superposition of exogenous sources was most significant for soil pollution. Exogenous sources of HMs included mining, industrial sources (such as the metal smelting plants, thermal power plants and alkylation plants) [ 14 , 15 , 16 , 17 ], agricultural sources (fertilizers, pesticides and livestock manure) [ 18 , 19 ] and traffic sources (wear of metal parts and exhaust emission) [ 20 ]. In addition, the soil of the karst area, compared to that of non-karst area, is characterized by thin regoliths, uneven distribution, and high porosity [ 21 , 22 ], which contributed to the migration of HMs from the surface to the subsoil and even contaminated underground water [ 9 , 23 ].…”