The patterns of bacterial community and relationships between sulfate-reducing bacteria and hydrochemistry in sulfate-polluted groundwater of Baogang rare earth tailings.

Xinli An,Jianqiang Su,Hu Li,Changping Yu,Paul Baker,Chao Cai

doi:10.1007/s11356-016-7381-y

Abstract

Microorganisms are the primary agents responsible for the modification, degradation, and/or detoxification of pollutants, and thus, they play a major role in their natural attenuation; yet, little is known about the structure and diversity of the subsurface community and relationships between microbial community and groundwater hydrochemistry. In this study, denaturing gradient gel electrophoresis (DGGE) and terminal restriction fragment length polymorphism (T-RFLP) allowed a comparative microbial community analysis of sulfate-contaminated groundwater samples from nine different wells in the region of Baogang rare earth tailings. Using real-time PCR, the abundance of total bacteria and the sulfate-reducing genes of aprA and dsrB were quantified. Statistical analyses showed a clear distinction of the microbial community diversity between the contaminated and uncontaminated samples, with Proteobacteria being the most dominant members of the microbial community. SO42- concentrations exerted a significant effect on the variation of the bacterial community (P<0.05), with higher concentrations of sulfate reducing the microbial diversity (H' index), indicating that human activity (e.g., mining industries) was a possible factor disturbing the structure of the bacterial community. Quantitative analysis of the functional genes showed that the proportions of dsrB to total bacteria were 0.002-2.85%, and the sulfate-reducing bacteria (SRB) were predominant within the prokaryotic community in the groundwater. The uncontaminated groundwater with low sulfate concentration harbored higher abundance of SRB than that in the polluted samples, while no significant correlation was observed between sulfate concentrations and SRB abundances in this study, suggesting other environmental factors possibly contributed to different distributions and abundances of SRB in the different sites. The results should facilitate expanded studies to identify robust microbe-environment interactions and provide a strong foundation for qualitative exploration of the bacterial diversity in rare earth tailings groundwater that might ultimately be incorporated into the remediation of environmental contamination.

Highlights

Human activities were involved in the exploration of mining industries, which have caused many environmental problems owing to the lack of the treatment techniques
The two techniques have their own limitations, for example, each band on denaturing gradient gel electrophoresis (DGGE) may correspond to a microorganism at a population level of 1% or greater and multiple bands of terminal restriction fragment length polymorphism (T-RFLP) may relate to the same group of microorganisms, the cooperation of DGGE and T-RFLP can be highly effective and low-cost in revealing bacterial community structure when compared with modern high throughput sequencing techniques (Camarinha-Silva et al 2012; Siri et al 2014; Sutton et al 2009; Vanni et al 2012)
Sulfate concentrations decreased from 4444 mg/L to 2.54 mg/L corresponding to wells GW-2, GW-4, GW-3, GW-6 and GW-7 in the order along the advective groundwater transport flow (Table 1)

Summary

Introduction

Human activities were involved in the exploration of mining industries, which have caused many environmental problems owing to the lack of the treatment techniques. Owing to the lack of useful treatment techniques and proper liners, most of the untreated acid mine water in the drainage system may percolate into the peripheral subsurface in the form of leachate, which exerts a detrimental effect on nearby terrestrial and aquatic ecosystems. This causes lack of water necessary for households and industries, loss or killing of crops and even deterioration of human health caused by water-related problems (e.g., pollution by arsenic, benzene, trichloroethene and so on) (Roling et al 2001, Kjeldsen et al 2002; Mouser et al 2010). The studies regarding to acid mine water and the resulting ecological effects should provide a solid foundation for the remediation of environmental contamination, in light of the potential damage these waters pose to sensitive eco-systems

Methods

Results

Conclusion