Water Quality and Microbial Community Assessment in Artisanal Mining- Affected Sediments of Cikidang River, Banten, Java, Indonesia

Sains Malaysiana 51(5)(2022): 1339-1352 http://doi.org/10.17576/jsm-2022-5105-06

ABSTRACT The total microbial diversity and community in submerged sediments near mining sites, transition and intact sites at Cikidang River, Banten were assessed using 16S rDNA sequence data and biodiversity indices. Assessed water quality parameters in the river were water current, dissolved oxygen (DO), pH, redox potential, salinity, temperature and turbidity. Microbial alpha diversity used were Shannon diversity index, ChaoI index and Operational Taxonomic Units (OTUs). These analyses indicated a total of 50 taxa of sediment microbes. Based on Shannon diversity index, the highest value was observed at mining site. High abundant microbes in sediments at mining sites for phylum, class, order, family and genera levels were represented by Proteobacteria, Gammaproteobacteria, Pseudomonadales, Moraxellaceae, and Acinetobacter, respectively. In contrast, high abundant microbes in the sediment of the intact site for each taxon consisted of Firmicutes, Alphaproteobacteria, Erysipelotrichales, Erysipelotrichaceae, and Erysipelothrix. The water quality of mining sites was characterised by alkaline pH (8.807, 95% CI: 8.624 - 8.990) and lower redox potential (59.000 mV, 95% CI: 36.233 - 81.767) that differed significantly from the intact sites (P<0.05). This study also confirmed that mining sites have a higher genus diversity. Research on potential microbes of related genus as bioremediators could be recommended for further study.

INTRODUCTION Sediment microbial communities are important natural components for biological activities in river and stream ecosystems. Understanding the microbial dynamics in community structure and function across freshwater environments can provide information on how ecosystems will change in response to nearby anthropogenic land use practices (Gibbons et al. 2014). Sediment microbial communities in river ecosystems are influenced by inputs from nearby ecosystems. Change of dissolved materials in water can cause the change of microbial community in water-sediment habitat. Artisanal mining is a gold mining method common in river streams. Impacts of artisanal mining on ecosystem and biodiversity have been widely reported which ranged from removal of significant soil volumes to the destruction of massive intact vegetation (de Jesus Pereira 2009; Funoh 2014; Girmay 2018; Macdonald et al. 2015; Meaza et al. 2017). Significant impacts of mining on sediment microbial communities are caused by inputs from sediment runoff. In a contaminated ecosystem like a mining site, high microbial diversity has been observed (Hewson & Fuhrman 2006). Several factors influenced this microbial diversity, including wave, sediment-water content, organic carbon content, chlorophyll a, enzyme activities and inorganic nutrients enrichment (Hewson et al. 2007; Polymenakou et al. 2005; Zhang et al. 2008). However, low microbial diversity has been observed due to a polluted environment. Böer et al. (2009) reported that high nutrient availability reduced diversity because of an increase in competitive exclusion. The competition might influence the distributions of dominant and minor microbial groups in the sediment. Recent studies of microbial diversity influenced by mining activities have received much attention (Fernandes et al. 2018). Fatimawali et al. (2020) reported a difference in microbial diversity between mining and intact sites. Microbial diversity was observed having either positive or negative correlations with the environmental conditions of mining sites (Deng et al. 2020). Likewise, Basu et al. (2015) observed abundant microbes in former chromium mining sites. While most literature reported microbial diversity in terrestrial sediments, information on microbial diversity in aquatic and submerged sediments are still limited. This information is immediately required regarding the presence of artisanal mining near the river because the river is the source for water supply and irrigation for people living nearby.

Cikidang River is located in Cisungsang village, Cibeber district, Lebak regency, Banten province,Indonesia. This river has high economic and ecological importance, as it provides support for the livelihood of a large number of community members who are mainly farmers. Recently, this river was threatened by artisanal mining activities and an area of 6445 Ha had been occupied by mining activities as reported by Kurniawan et al. (2013). In contaminated rivers, nutrients and hazardous pollutants exist simultaneously in the sediment. Likewise, few studies have been conducted to investigate the microbial communities in contaminated river sediments related to the artisanal mining activities nearby. Here, the objectives of this study were to explore the profile of total sediment microbial diversity in contaminated river sediment adjacent to the mining sites. The microbial diversity was assessed using 16S rDNA sequence data.

Sains Malaysiana 51(5)(2022): 1339-1352 http://doi.org/10.17576/jsm-2022-5105-06