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Influence of heavy metals and PCBs pollution on the enzyme activity and microbial community of paddy soils around an e-waste recycling workshop.

Tang X, Hashmi MZ, Long D, Chen L, Khan MI, Shen C - Int J Environ Res Public Health (2014)

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310058, China. xianjin@zju.edu.cn.

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.

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PCA analysis results based on DGGE profiles of paddy soil samples ((A): bacteria, (B): actinomycetes).
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ijerph-11-03118-f005: PCA analysis results based on DGGE profiles of paddy soil samples ((A): bacteria, (B): actinomycetes).

Mentions: PCA of soil fingerprints (DGGE bands) is a useful tool to detect shifts in the microbial composition of mixed contaminated soil [9]. PCA results based on the DGGE profiles of paddy soil are shown in Figure 5 and reveal that the microbial community structure of P1 was similar to that of P2 but different from that of P3, P4, P5, and P6. For the P1 and P2, there was no significant difference of four heavy metals except Zn and Cu. PCBs levels in these two sites (12.1 and 21.6 μg·kg−1, respectively) were also obviously higher compared to other sites. It seems that the similar levels of mixed contamination especially PCBs in these two sites might possibly contribute to the similar microbial community structure in soil, although there were other various factors such as the co-abundance of different organisms and the same soil water content in paddy soil as we discussed above. The differences in bacterial community structure were not significant among P3, P5 and P6. While PCA results for the actinomycetes revealed that there was minor difference in the community structure between two consecutive sites (P3–P6, Figure 5B). Over all, there was no good relationship to be found between the microbial parameters including enzyme actives and DGGE results with mixed contaminations of heavy metals and PCBs in our study. Although Wang et al. [9] suggested that there were negative correlations among microbial biomass, enzyme activity, and metals in soil with different distances from a smelter. The PCR-DGGE analysis results also indicated that soil-available metals concentrations were well correlated with the relative abundance of Comamonadaceae, Moraxellaceae, and other bacterial communities in soil [45]. 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. Due to the emerging environmental issues of e-waste, the potential threats of mixed contamination to the quality and health of paddy soil should be further studied.


Influence of heavy metals and PCBs pollution on the enzyme activity and microbial community of paddy soils around an e-waste recycling workshop.

Tang X, Hashmi MZ, Long D, Chen L, Khan MI, Shen C - Int J Environ Res Public Health (2014)

PCA analysis results based on DGGE profiles of paddy soil samples ((A): bacteria, (B): actinomycetes).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3987024&req=5

ijerph-11-03118-f005: PCA analysis results based on DGGE profiles of paddy soil samples ((A): bacteria, (B): actinomycetes).
Mentions: PCA of soil fingerprints (DGGE bands) is a useful tool to detect shifts in the microbial composition of mixed contaminated soil [9]. PCA results based on the DGGE profiles of paddy soil are shown in Figure 5 and reveal that the microbial community structure of P1 was similar to that of P2 but different from that of P3, P4, P5, and P6. For the P1 and P2, there was no significant difference of four heavy metals except Zn and Cu. PCBs levels in these two sites (12.1 and 21.6 μg·kg−1, respectively) were also obviously higher compared to other sites. It seems that the similar levels of mixed contamination especially PCBs in these two sites might possibly contribute to the similar microbial community structure in soil, although there were other various factors such as the co-abundance of different organisms and the same soil water content in paddy soil as we discussed above. The differences in bacterial community structure were not significant among P3, P5 and P6. While PCA results for the actinomycetes revealed that there was minor difference in the community structure between two consecutive sites (P3–P6, Figure 5B). Over all, there was no good relationship to be found between the microbial parameters including enzyme actives and DGGE results with mixed contaminations of heavy metals and PCBs in our study. Although Wang et al. [9] suggested that there were negative correlations among microbial biomass, enzyme activity, and metals in soil with different distances from a smelter. The PCR-DGGE analysis results also indicated that soil-available metals concentrations were well correlated with the relative abundance of Comamonadaceae, Moraxellaceae, and other bacterial communities in soil [45]. 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. Due to the emerging environmental issues of e-waste, the potential threats of mixed contamination to the quality and health of paddy soil should be further studied.

Bottom Line: 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).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.

View Article: PubMed Central - PubMed

Affiliation: College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310058, China. xianjin@zju.edu.cn.

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.

Show MeSH