Does what we find depend on how we sample? Measured streambed microplastic concentrations can be affected by the choice of sampling method.

Microplastics (MPs) are prevalent in rivers worldwide and can adversely impact riverine ecosystems. To sample for MPs in streambeds, a variety of different sampling techniques is applied, including (i) scooping, (ii) coring, (iii) freeze coring, (iv) resuspension method, and (v) piezometer sampling. These common sampling techniques capture different parts of the streambed and different sampling volumes.

The Duration of Dry Events Promotes PVC Film Fragmentation in Intermittent Rivers.

The majority of microplastics (MPs) found in the environment originate from plastic fragmentation occurring in the environment and are influenced by environmental factors such as UV irradiation and biotic interactions. However, the effects of river drying on plastic fragmentation remain unknown, despite the global prevalence of watercourses experiencing flow intermittence. This study investigates, through laboratory experiments, the coupled effects of drying duration and UV irradiation on PVC film fragmentation induced by artificial mechanical abrasion.

Optimization of glass separating funnels to facilitate microplastic extraction from sediments.

Recent studies on the distribution of microplastics in aquatic sediments have deployed different methods and devices for density separation of microplastics from sediments. However, instrument specific limitations have been noted, including their high cost, difficulty in handling, or/and the potential for elevated contamination risk due to their plastic composition. This study improves existing sediment microplastic separation techniques by modifying the commonly used conical shape glass separating funnels.

Warming drives feedback between plant phenotypes and ecosystem functioning in sub-Antarctic ponds.

Ample evidence indicates that warming affects individuals in plant communities, ultimately threatening biodiversity. Individual plants in communities are also exposed to plant-plant interaction that may affect their performance. However, trait responses to these two constraints have usually been studied separately, while they may influence processes at the ecosystem level.

Determination of groundwater origins and vulnerability based on multi-tracer investigations: New contributions from passive sampling and suspect screening approach.

Knowledge about groundwater origins and their interactions with surface water is fundamental to assess their vulnerability. In this context, hydrochemical and isotopic tracers are useful tools to investigate water origins and mixing. More recent studies examined the relevance of contaminants of emerging concern (CECs) as co-tracers to distinguish sources contributing to groundwater bodies.

Sediment reworking of intertidal sediments by the benthic foraminifera : the importance of motion behaviour and densities.

This study aimed to describe for the first time the vertical motion behaviour of the intertidal foraminifera and its contribution to bioturbation. Its infaunal behaviour leads to the creation of a one-end tube within the first centimetre of sediment. In addition, a vertical trail following behaviour was described for the first time in foraminifera, which may be linked to the sustainability of the biogenic sedimentary structures.

Microplastics in Freshwater Sediments Impact the Role of a Main Bioturbator in Ecosystem Functioning.

While microplastic transport, fate, and effects have been a focus of studies globally, the consequences of their presence on ecosystem functioning have not received the same attention. With increasing evidence of the accumulation of microplastics at sediment-water interfaces there is a need to assess their impacts on ecosystem engineers, also known as bioturbators, which have direct and indirect effects on ecosystem health. This study investigated the impact of microplastics on the bioturbator alongside any effects on the biogeochemical processes at the sediment-water interface.

Environmental and land use controls of microplastic pollution along the gravel-bed Ain River (France) and its "Plastic Valley".

Understanding microplastic particles (MPs) accumulation and transport along rivers represents a major task due to the complexity and heterogeneity of rivers, and their interactions with their wider corridor. The identification of MPs hotspots and their potential sources is especially challenging in coarse-bed rivers transporting a wide range of particle sizes with a high degree of variability in time and space. This research focuses on the gravel-bed Ain River (Rhône River tributary, France) which is managed by means of various dams and also hosts one of the major plastic production centres in Europe (Oyonnax and Bienne Plastic Valleys).

Aquifer recharge by stormwater infiltration basins: Hydrological and vadose zone characteristics control the impacts of basins on groundwater chemistry and microbiology.

Stormwater infiltration systems (SIS) are designed to collect and infiltrate urban stormwater runoff into the ground for flood risk mitigation and artificial aquifer recharge. Many studies have demonstrated that infiltration practices can impact groundwater chemistry and microbiology. However, quantitative assessments of the hydrogeological factors responsible of these changes remain scarce.

Drivers of functional diversity in the hyporheic zone of a large river.

The effects of regional (hydrogeology and geomorphology) and local (sediment and hydrology) characteristics on hyporheic assemblages were studied along a 40-km reach of a large gravel-bed river. Hyporheic water and fauna were sampled at the upstream and downstream positions of 15 large gravel bars. The resulting 30 stations varied in their sediment grain size, stability and direction of river-aquifer exchanges.

Scale-dependent effects of vegetation on flow velocity and biogeochemical conditions in aquatic systems.

In rivers, scale-dependent feedbacks resulting from physical habitat modifications control the lateral expansion of submerged plant patches, while the mechanisms that limit patch expansion on a longitudinal dimension remain unknown. Our objective was to investigate the effects of patch length on physical habitat modification (i.e.

Effects of bioturbation by tubificid worms on biogeochemical processes, bacterial community structure and diversity in heterotrophic wetland sediments.

Bioturbation activity of tubificid worms has been recognized as a key process influencing organic matter processing and nutrient cycling in benthic aquatic ecosystems. This activity is expected to modify benthic microbial communities by affecting the physical and chemical environment in sediments. Nevertheless, quantifications of bacterial community changes associated with bioturbation in freshwater ecosystems are still lacking.

Multiple stressors shape invertebrate assemblages and reduce their trophic niche: A case study in a regulated stream.

Unlabelled: Few studies have addressed how the diversity of basal resources change with stream regulation and the potential consequences on river biota. We sampled invertebrates above and below a series of dams, over two years, at both downwelling and upwelling zones. In each zone, we recorded the daily temperature and flow variations, estimated the algal development, measured the available resources, and analysed carbon and nitrogen stable isotope compositions of the invertebrate community.

3D modelling of solute transport and mixing during managed aquifer recharge with an infiltration basin.

Artificial basins are used to recharge groundwater by many municipalities to improve the sustainability of storm water management. Despite its increasing operational implementation, artificial recharge still raises numerous questions related to its impact on groundwater quality. In this paper, a 3D numerical model of MAR basin/aquifer system was implemented in order to simulate the fate of water and pollutants.

Gathering at the top? Environmental controls of microplastic uptake and biomagnification in freshwater food webs.

Microplastics are ubiquitous in the environment, with high concentrations being detected now also in river corridors and sediments globally. Whilst there has been increasing field evidence of microplastics accumulation in the guts and tissues of freshwater and marine aquatic species, the uptake mechanisms of microplastics into freshwater food webs, and the physical and geological controls on pathway-specific exposures to microplastics, are not well understood. This knowledge gap is hampering the assessment of exposure risks, and potential ecotoxicological and public health impacts from microplastics.

Influence of stormwater infiltration systems on the structure and the activities of groundwater biofilms: Are the effects restricted to rainy periods?

Stormwater infiltration systems (SIS) have been set up to collect and infiltrate urban stormwater runoff in order to reduce flooding and to artificially recharge aquifers. Such practices produce environmental changes in shallow groundwater ecosystems like an increase in organic matter concentrations that could drive changes in structure and functions of groundwater microbial communities. Previous works suggested that SIS influence groundwater physico-chemistry during either rainy and dry period but no study has examined the impact of SIS on groundwater microorganisms during both periods.

Emerging polar pollutants in groundwater: Potential impact of urban stormwater infiltration practices.

The quality of groundwater (GW) resources is decreasing partly due to chemical contaminations from a wide range of activities, such as industrial and agricultural enterprises and changes in land-use. In urban areas, one potential major pathway of GW contamination is associated with urban water management practices based on stormwater runoff infiltration systems (SIS). Data on the performance of the upper layer of soil and the unsaturated zone of infiltration basins to limit the contamination of GW by hydrophilic compounds are lacking.

Ecological assessment of groundwater ecosystems disturbed by recharge systems using organic matter quality, biofilm characteristics, and bacterial diversity.

Recharge of aquifers by urban stormwater may trigger significant ecological changes that can be detrimental to the biodiversity and functioning of groundwater ecosystems. Here, the effects of aquifer recharge (AR) on three levels of parameters were investigated: dissolved organic carbon (DOC) quantity and quality, global biofilm characteristics, and diversity changes of bacterial communities. As DOC enrichment by AR can be mitigated by vadose zone (VZ) thickness, three AR sites with thin VZ (< 3 m) and three sites with thick VZ (> 10 m) were selected.

Calibration and field application of an innovative passive sampler for monitoring groundwater quality.

This study describes the development of a novel Empore™ disk-based passive sampler specially adapted to groundwater monitoring. The sampler was calibrated in the laboratory using conditions that corresponded to groundwater (i.e.

Use of passive sampling and high resolution mass spectrometry using a suspect screening approach to characterise emerging pollutants in contaminated groundwater and runoff.

Groundwater systems are being increasingly used to provide potable and other water supplies. Due to human activities, a range of organic pollutants is often detected in groundwater. One source of groundwater contamination is via stormwater infiltration basins, however, there is little information on the types of compounds present in these collection systems and their influence on the underlying groundwater.

Clay beads as artificial trapping matrices for monitoring bacterial distribution among urban stormwater infiltration systems and their connected aquifers.

Stormwater infiltration systems (SIS) have been developed to limit surface runoff and flooding in urban areas. The impacts of such practices on the ecological and biological quality of groundwater ecosystems remain poorly studied due to the lack of efficient methodologies to assess microbiological quality of aquifers. In the present study, a monitoring method based on the incubation of artificial matrices (clay beads) is presented to evaluate microbial biomass, microbial activities, and bacterial community structure.

Aquifer recharge with stormwater runoff in urban areas: Influence of vadose zone thickness on nutrient and bacterial transfers from the surface of infiltration basins to groundwater.

Stormwater infiltration systems (SIS) have been built in urban areas to reduce the environmental impacts of stormwater runoff. Infiltration basins allow the transfer of stormwater runoff to aquifers but their abilities to retain contaminants depend on vadose zone properties. This study assessed the influence of vadose zone thickness (VZT) on the transfer of inorganic nutrients (PO, NO, NH), dissolved organic carbon (total -DOC- and biodegradable -BDOC-) and bacteria.

Less effective selection leads to larger genomes.

The evolutionary origin of the striking genome size variations found in eukaryotes remains enigmatic. The effective size of populations, by controlling selection efficacy, is expected to be a key parameter underlying genome size evolution. However, this hypothesis has proved difficult to investigate using empirical data sets.

No Evidence That Nitrogen Limitation Influences the Elemental Composition of Isopod Transcriptomes and Proteomes.

The field of stoichiogenomics aims at understanding the influence of nutrient limitations on the elemental composition of the genome, transcriptome, and proteome. The 20 amino acids and the 4 nt differ in the number of nutrients they contain, such as nitrogen (N). Thus, N limitation shall theoretically select for changes in the composition of proteins or RNAs through preferential use of N-poor amino acids or nucleotides, which will decrease the N-budget of an organism.

Ecological Engineering Approaches to Improve Hydraulic Properties of Infiltration Basins Designed for Groundwater Recharge.

Infiltration systems are increasingly used in urban areas for groundwater recharge. The reduction of sediment permeability by physical and/or biological processes is a major problem in management of infiltration systems often requiring expensive engineering operations for hydraulic performance maintenance. To reduce these costs and for the sake of sustainable development, we proposed to evaluate the ability of ecological engineering approaches to reduce the biological clogging of infiltration basins.