Anthropogenic pollutants affect ecosystem services of freshwater sediments: the need for a “triad plus x” approach

Abstract

Purpose Freshwater sediments and their attached microbial communities (biofilms) are essential features of rivers and lakes, providing valuable ecosystem services such as nutrient recycling or self-purification which extend beyond the aquatic environment. Anthropogenic pollutants, whether from the industrial era or as a result of our contemporary lifestyles, can negatively affect these functions with hitherto unknown consequences on ecology, the economy and human health.Thus far, the singular view of the involved disciplines such as ecotoxicology, environmental microbiology, hydrology and geomorphology has prevented a deeper understanding of this emerging issue. Main features This paper discusses briefly the progressions and the state-of-the-art methods within the disciplines of concern related to contaminated sediments, ranging from ecotoxicological test systems, microbiological/molecular approaches to unravel changes of microbial ecosystems, up to the modelling of sediment transport and sorption/desorption of associated pollutants. The first bilateral research efforts on contaminated sediments include efforts to assess ecotoxicological sediment risk including sediment mobility (i.e. ecotoxicology and engineering), enhance bioremediation potential (i.e. microbiology and ecotoxicology) or to understand biostabilisation processes of sediments by microbial assemblages (i.e. microbiology and engineering). Conclusions and perspectives In freshwater habitats, acute, chronic and mechanism-specific toxic effects on organisms, shifts in composition, structure and functionality of benthic microbial communities, as well as the obstruction of important ecosystem services by continuously discharged and long-deposited pollutants, should be related to the in situ sediment dynamics. To achieve an improved understanding of the ecology of freshwater sediments and the impairment of their important ecosystem functions by human-derived pollutants, we suggest a "triad plus x" approach combining advanced methods of ecotoxicology, environmental microbiology and engineering science.

Quantifying biostabilisation effects of biofilm-secreted and extracted extracellular polymeric substances (EPSs) on sandy substrate

“…The implementation of biological processes into sediment transport equations that have traditionally been modelled as abiotic systems is expected to result in better predictions of sediment dynamics (Black et al, 2002;Righetti and Lucarelli, 2007;Gerbersdorf et al, 2011;Parsons et al, 2016). Our study confirms that extracted EPSs xanthan gum and carrageenan are not perfect analogues of natural biofilms (Perkins et al, 2004), but they are capable of introducing realistic biological cohesion into flume facilities in a fast and controlled manner for a range of commonly used conditions.…”

“…Micro-organisms are a fundamental feature of aquatic environments providing a range of ecosystem services (Gerbersdorf et al, 2011;Gerbersdorf and Wieprecht, 2015). A large variety of microbial assemblages ("biofilms") such as microphytobenthos, microbial mats and biofouling in pipes (Flemming and Wingender, 2010) are representations of microbial communities in aqueous environments.…”

“…A large variety of microbial assemblages ("biofilms") such as microphytobenthos, microbial mats and biofouling in pipes (Flemming and Wingender, 2010) are representations of microbial communities in aqueous environments. The microbes in biofilms live in a self-formed matrix of gluelike and hydrated extracellular polymeric substances (EPSs) such as polysaccharides (often 40-95 %), proteins (up to 60 %) and minor amounts of acids, lipids and biopolymers (Decho, 1990;Flemming, 2011;Gerbersdorf et al, 2011). The ecosystem functions of EPSs in sediment particle aggregation, increasing sediment stability, altering chemical properties to enable contaminant release or adsorption and providing a food source for invertebrates are well established for marine environments (Decho, 1990;Passow, 2002;Bhaskar and Bhosle, 2006;Paterson et al, 2008) but remain less well understood for freshwater systems (Gerbersdorf et al, 2011).…”

Recent advances and future directions in soils and sediments research

“…Garcia-Aragon et al 2011) have demonstrated the role of periphyton, biofilms and extracellular polymeric substances (EPS) in stabilizing channel bed sediment from erosion and resuspension, thereby limiting the remobilization of contaminated sediment. Indeed Gerbersdorf et al (2011) argue that such process understanding should be part of sediment quality assessment. Much of this work on the hydrodynamic and biogeochemical processes operating at the sediment-water interface has involved the use of experimental facilities, such as flumes and within laboratories (e.g.…”

Combining Field and Laboratory Measurements to Determine the Erosion Risk of Cohesive Sediments Best

“…Increased hydraulic forces such as floods or dredging activities might remobilize these old burdens to become bioavailable and toxic again [16,17]. The latter has become sad reality with huge ecological and economic aftermaths e.g., during the floods in 2002 and 2014 in the East part of Germany [18][19][20]. The present investigations are reasoned by the aim to better judge on sites of high contamination risk in order to take necessary precautions and initiate countermeasures.…”