Distribution Characteristics and Pollution Assessment of Soil Heavy Metals under Different Land-Use Types in Xuzhou City, China

Aman Fang,Jihong Dong,Yingli An

doi:10.3390/su11071832

Aman Fang, Jihong Dong + Show 1 more

Open Access

https://doi.org/10.3390/su11071832

Copy DOI

Journal: Sustainability	Publication Date: Mar 27, 2019
Citations: 15	License type: CC BY 4.0

Affiliation: China University of Mining and Technology

Abstract

Xuzhou, as a mining city in China, has been experiencing 130 years of coal mining and processing. To explore the spatial distribution characteristics and pollution status of soil heavy metals (Cr, Cd, As, Hg, Zn, and Pb) under different land-use types, a total of 2697 topsoil samples were collected in all of the areas (except for water) of Xuzhou in 2016. Overall, the mean concentrations of Cr (70.266 mg/kg), Cd (0.141 mg/kg), As (10.375 mg/kg), Hg (0.036 mg/kg), Zn (64.788 mg/kg), and Pb (24.84 mg/kg) in Xuzhou soils were lower than the environmental quality standard for soils (GB15618-1995). However, the mean concentrations of Cr, Hg, and Pb exceeded their corresponding background values, with the mean concentration of Hg being almost three times its background value. For different land-use types, the highest mean concentration of Cr was concentrated in grassland soils. The mean concentrations of Cd, As, Zn, and Pb in mining area soils were higher than those in the other soils. The mean concentration of Hg was the highest in the built-up area soils. Based on the potential ecological risk assessment, the forestland, garden land, grassland, and others were at low and moderate risk levels, the farmland and mining area were at low, moderate, and high risk levels, and the built-up area was at various risk levels in Xuzhou. There was a significant positive correlation between Cr, Pb, and Hg concentrations and the corresponding organic carbon contents in the farmland, built-up area, garden land, forestland, and other soils ( p < 0.01 ). A high degree of correlation was found between Cr and Hg concentrations, as well as organic carbon contents in grassland soils, with values of p < 0.05 and p < 0.01 , respectively. An obvious correlation could be seen between Hg concentrations and organic carbon contents in mining area soils ( p < 0.01 ).

Highlights

In China, the main types of land use are farmland, built-up area, mining area, forestland, garden land, grassland, water, and others [1]
If the coefficient of variation (CV) ≤ 20, it indicates low variability; 21% < CV ≤ 50% is considered moderate variability; 50% < CV≤ 100% is observed as high variability; and a CV above 100% is regarded as exceptionally high variability [39]
The mean concentrations of Cr, Cd, Pb, Zn, Hg, and As in Xuzhou were less than the environmental quality standard for soils in China, but the mean concentrations of Cr, Hg, and Pb exceeded their corresponding background values of Xuzhou

Summary

Introduction

In China, the main types of land use are farmland, built-up area, mining area, forestland, garden land, grassland, water, and others [1]. Cities that have traditionally been dominated by the coal mining industry, such as Fushun, Datong, Tangshan, Pingdingshan, Xuzhou, Huaibei, and so on [2,3], are in the main grain-producing areas [4]. Forestland, and grassland play a major role in grain production and ecological safety in these cities. Large-scale coal-fired power generation, and the accelerated urban growth during the last few decades have been responsible for the degradation of the soil quality of different land types. Soil is one of the basic environmental media, and it can be contaminated through the accumulation of heavy metals through the discharge of effluents from mine tailings, coal combustion, sewage sludge, the disposal of high-metal wastes, and land application of fertilizers. Metal-contaminated crops from contaminated soils pose a threat to human health as a consequence of inhalation or ingestion through the food chain [5,6]

Objectives

Methods

Results

Conclusion