Study of Heavy Metals and Microbial Communities in Contaminated Sediments Along an Urban Estuary

Abstract

Estuarine sediments are increasingly contaminated by heavy metals as a result of urbanization and human activities. Continuous multi-heavy metal accumulation in the ecosystem can provoke new effects on top of the complex environmental interactions already present in estuarine ecosystems. It is important to study their integrated influence on imperative microbial communities to reflect on the environmental and ecological risks they may impose. Inductively coupled plasma optical emission spectroscopy analysis for five metals Cd, Cr, Cu, Pb, and Zn showed that Cr and Cu concentrations in intertidal sediments of the urbanized Yangtze River estuary in China have consistently exceeded respective threshold effect concentration (TEC) levels. The geo-accumulation and potential ecological risk index results of the five metals showed that all sampling sites were weakly to moderately polluted, and at considerable to high ecological risk, respectively. Redundancy and correlation analyses showed that Zn followed by Cr in the ecosystem were explanatory of the shifts in recorded microbial community structures. However, the spatial variation in metal concentrations did not correspond to the selection of metal resistance genes (MRGs). Unlike many other dominant bacterial taxa, most of the sulfate-reducing bacteria (SRB) and associated sulfate respiration as the dominant microbially contributed ecological function were found to negatively correlate with Zn and total heavy metal pollution. Zn concentration was proposed to be a potent indicator for heavy metal pollution-associated microbial community compositional shifts under urbanized estuarine conditions. The associations between heavy metals and estuarine microbial communities in this study demonstrate the influence of heavy metals on microbial community structure and adaptations that is often overshadowed by environmental factors (i.e., salinity and nutrients).

Exploring the diversity and structural response of sediment-associated microbiota communities to environmental pollution at the siangshan wetland in Taiwan using environmental DNA metagenomic approach

“…Other important phyla observed in this study are, Actinobacterota, Planctomycetota, Acidobacteriota, Gemmatimonadota, Myxococcota, and Halobacteriota (Archaea) as the most abundant. All the abundant microbial phyla obtained in this study have been documented previously in other metal-contaminated environments, such as sediments (Lee et al, 2021;Rajeev et al, 2021;Yi et al, 2021;Custodio et al, 2022), iron tailing pond (Li et al, 2021), mining soils (Cao et al, 2017;Hemmat-Jou et al, 2018;Liu et al, 2021a), paddy soils (Tseng et al, 2021), arid loess region (Zeng et al, 2020), and electric waste soils (Jiang et al, 2019), this suggests that these phyla are associated with metal-polluted sediment.…”

Diversity of Microbial Communities, PAHs, and Metals in Road and Leaf Dust of Functional Zones of Moscow and Murmansk

“…It seems that environmental factors that influence the fungal microbiome composition are different from those that impact bacterial microbiomes [ 58 ]. For example, for contaminated soils and sediments, studies have shown that bacterial and fungal communities may exhibit differences in their response to heavy metals [ 59 , 60 , 61 , 62 , 63 , 64 ]. This is partly based on common differences in the biochemical pathways activated by bacteria and fungi in response to heavy metals and PAHs [ 65 , 66 , 67 ].…”

A Matter of Metals: Copper But Not Cadmium Affects the Microbial Alpha-Diversity of Soils and Sediments, a Meta-Analysis

“…Previous investigations of polluted soils and sediments suggested that microorganism exposure to HM follows precise ecotoxicological rules [51]- [53]. However, it is currently thought that HM induce different responses in bacterial and fungal communities [54], [55].…”