Heavy metal pollution and ecological risk under different land use types: based on the similarity of pollution sources and comparing the results of three evaluation models

Abstract

In key areas of ecological protection, it is significant to consider the similarity of pollution sources among heavy metals and the interaction between different sources, especially the ecological risk areas caused by heavy metal pollution. We collected 51 soil samples from five land use types with different soil depths in an industrial area on the Qinghai-Tibet Plateau. Two and three major heavy metal combination types of Cd Cu Cr Pb and Zn in different soil layers were identified using absolute principal component score-multiple linear regression models, and the potential pollution sources corresponding to the different types were quantified using Geo-Detector models. Industrial activities, especially metallurgy and mining, are the most likely potential sources of Cd Cu and Pb pollution, while the enrichment effects caused by rivers and roads are also evident in the study area. Heavy metal levels were generally higher in watered and urban lands and lower in grasslands. The downward migration of heavy metals in the study area was inferred from the similar trends of several indicators between soil layers A and B. The new model Nemerow Integrated Risk Index (NIRI) was used to analyse the integrated ecological risk across the study area and under different land use types by comparing with the pollution load index and Nemerow Integrated Pollution Index, and it was found that the risk level was lower in grassland and forest land than under other land use types, while it was higher in urban land and irrigated land. NIRI was able to highlight the impact of high Cd toxicity factors on the overall risk level, and is more accurate and flexible in identifying risk areas.

Study on the soil pollution condition around the domestic wastewater

“…Domestic wastes fall into the soil and create pollution processes and lead to soil pollution with chemicals such as Bi, Mo, Sb, Cu, Pb, Hg, Ag, As, Sn, Cr, Se, Zn contained in the wastes [3]. Household waste is a potential source of heavy metals-Cd, Pb, Zn, Cu and Cr pollution and pollutes water, soil and plants [4], the amount of heavy metals such as Cd, Pb, Cu, Ni, Zn increases in polluted soils [5,6,7], absorbed by the roots of and plants and causes the death of plants [8,9]. The norm of heavy metals in healthy soils around the world: Hg -35 mg/kg, Zn -108 mg/kg, As -11 mg/kg, Cr -71 mg/kg, Ni -43 mg/kg, Co -18 mg/kg, Cu -56 mg/kg, Mo -3.1 mg/kg, Mn -397 mg/kg, Ba -496 mg/kg, V -62 mg/kg.…”