Effects of multi-walled carbon nanotubes on metabolic function of the microbial community in riverine sediment contaminated with phenanthrene

Abstract

The ecological risks of carbon nanotubes in the aquatic environment are of great concern. In this work, the effects of multi-walled carbon nanotubes (MWCNTs) on metabolic function of the microbial community in sediment contaminated with phenanthrene were investigated. The metabolic function was evaluated by Biolog ECO microplates a month later after MWCNTs of various dosages (0.5%, 1.0%, and 2.0%, w/w) were incorporated into the phenanthrene-contaminated sediment. The self-organizing map (SOM) algorithm and principal components analysis were used for data processing. The incorporation of 0.5% MWCNTs into the contaminated sediment significantly enhanced microbial activity (from 0.83 to 0.92, average well color development) and Shannon-Wiener diversity index (from 3.19 to 3.23) compared with the blank control. Clustering the microbial communities in different treatments on the trained SOM suggested that phenanthrene had a greater impact on the metabolic function of sediment microbial communities than MWCNTs in the experiments. The metabolic differences caused by MWCNTs were mainly reflected in the utilization of amino acids and polymers. The results of this study may contribute to evaluating the ecological risks of MWCNTs in the aquatic environment and developing the secure applications of MWCNTs.