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Available forms of nutrients and heavy metals control the distribution of microbial phospholipid fatty acids in sediments of the Three Gorges Reservoir, China

Abstract

The construction of the Three Gorges Reservoir (TGR) as well as the development of local industry and agriculture not only had tremendous impacts on the environment but also affected human health. Although water, soil, and air in the TGR have been well studied for environmental risk assessment, very little information is available on benthic sediments and microorganisms. In this study, sedimentary samples were collected along the main stream of the TGR to examine microbial phospholipid fatty acids (PLFA) and relevant variables (e.g., nutrients and heavy metals) after the full operation of the TGR. The results showed that there were prominent trends (increase or decrease) of sedimentary PLFAs and properties from downstream to upstream. Bacteria-specific PLFA decreased toward the dam, while fungi-specific PLFA did not show any significant trend. The PLFA ratio of fungi to bacteria (F/B) increased along the mainstream. The total PLFA concentration, which represents the microbial biomass, decreased significantly toward the dam. Upstream and downstream sampling points were clearly distinguished by PLFA ordination in the redundancy analysis (RDA). That finding showed microbial PLFAs to have an obvious distribution pattern (increase or decrease) in the TGR. The PLFA distribution was markedly controlled by nutrients and heavy metals, but nutrients were more important. Moreover, among nutrients, Bio-P, NH4 +-N, NO3 -N, and DOC were more important than TP, TN, TOC, and pH in controlling PLFA distribution. For heavy metals, Tl, V, Mo, and Ni were more important than Zn, Cu, Cd, and Pb. These findings suggested that Tl, V, Mo, and Ni should not be ignored to guard against their pollution in the TGR, and we should pay attention to them and make them our first priority. This study highlighted that the construction of the TGR changed riverine environments and altered microbial communities in sediments by affecting sedimentary properties. It is a reminder that the microbial ecology of sediment as an indicator should be considered in assessing the eco-risk of the TGR.

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Funding

This work was supported by the open fund of Key Laboratory of Mountain Surface Processes and Ecological Regulation in Chinese Academy of Sciences and Science Foundation for Young Scientists, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences.

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Correspondence to Yanhong Wu.

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Responsible editor: Robert Duran

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Fig. S1
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The sedimentation environment in TGR. (GIF 249 kb)

Fig. S2
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(c) Redundancy analysis (RDA) of the sediment PLFAs using environmental parameters (the nutrients (Nutr) and bioavailable forms of heavy metals (BioHM)) as explanatory variables. The dis-TGD: the distance to Three Gorges Dam. The significance of the relations between the ordination and explanatory variables is denoted as follow:* p < 0.05, ** p < 0.01; *** p < 0.001. (d) A partial RDA showed the proportion of the variance in PLFAs composition explained by the nutrients (Nutr) and bioavailable forms of heavy metals (BioHM). (GIF 71 kb)

Fig. S3
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Spatial distribution of bedrocks in TGRR (Bao et al., 2015). (GIF 145 kb)

Fig. S4
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The percentage of particles in sediments from upstream to downstream of TGR. The percentage of particle size was measured by the laser particle size analyzer (Mastersizer 2000, UK) (GIF 19 kb)

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Sun, H., Wu, Y., Bing, H. et al. Available forms of nutrients and heavy metals control the distribution of microbial phospholipid fatty acids in sediments of the Three Gorges Reservoir, China. Environ Sci Pollut Res 25, 5740–5751 (2018). https://doi.org/10.1007/s11356-017-0824-2

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  • DOI: https://doi.org/10.1007/s11356-017-0824-2

Keywords

  • Bottom sediments
  • Microbial community
  • Phospholipid fatty acids
  • Nutrients
  • Heavy metal