Influence of Heavy Metals and PCBs Pollution on the Enzyme Activity and Microbial Community of Paddy Soils around an E-Waste Recycling Workshop

Xianjin Tang,Litao Chen,Muhammad Khan,Chaofeng Shen,Muhammad Hashmi,Dongyan Long

doi:10.3390/ijerph110303118

Abstract

Due to the emerging environmental issues related to e-waste there is concern about the quality of paddy soils near e-waste workshops. The levels of heavy metals and PCBs and their influence on the enzyme activity and microbial community of paddy soils obtained from the immediate vicinity of an e-waste workshop were investigated in the present study. The results indicated that the heavy metal and PCB pollution did not differ significantly with an increase of the sampling point distances (5 to 30 m). The concentration of Cd (2.16 mg·kg−1) and Cu (69.2 mg·kg−1) were higher, and the PCB pollution was also serious, ranging from 4.9 to 21.6 μg·kg−1. The highest enzyme activity was found for urease compared to phosphatase and catalase, and a fluctuating trend in soil enzyme activity was observed in soils from different sampling sites. The microbial analysis revealed that there was no apparent correlation between the microbial community and the pollutants. However, a slight influence for soil microbial communities could be found based on DGGE, the Shannon index and PCA analysis. The present study suggests that the contamination stress of heavy metals and PCBs might have a slight influence on microbial activity in paddy soils. This study provides the baseline data for enzyme activities and microbial communities in paddy soil under the influence of mixed contamination.

Highlights

Electronic and electric waste (e-waste), defined as end-of-life electronic products, including computers, television sets, mobile phones, transformers, capacitors, wires and cables, are a major environmental concern in China and other countries [1]
Since soil microbial community structure is an important component in the regulation of the soil microbial activity [42], and the toxicity effects of chemical pollutants on soil microbial activity have been confirmed [46], the microbial community shifts in the present study suggests that the contamination stress of heavy metals and PCBs might pose a slight influence on microbial activity in paddy soil
This study was conducted to investigate the influence of heavy metals and PCBs on the microbial community structure in paddy soil from Taizhou, China

Summary

Introduction

Electronic and electric waste (e-waste), defined as end-of-life electronic products, including computers, television sets, mobile phones, transformers, capacitors, wires and cables, are a major environmental concern in China and other countries [1]. Environment Programme (UNEP), approximately 50%–80% of global e-waste is legally or illegally imported into Asia each year, and about 90% of these e-wastes end up in China where they are illegally recycled in plants or workshops for the profit [2,3,4]. The Taizhou region of China is considered the largest e-waste recycling area with both open small e-waste recycling workshops and closed large system plants [5]. As the quality of the paddy system is important to the agricultural ecosystem and human health, a typical paddy soil from close to an e-waste recycling workshop in the Taizhou region was selected and the quality of paddy soil influenced by the mixed pollution was investigated in this study

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Results

Conclusion