A global systematic literature review of river sediment contamination was undertaken, based on secondary data published between 2015 and 2023, to identify the key challenges. It further explores how incidents of flooding, driven by climate change, can exacerbate the remobilization of contaminants, and cautiously discusses their potential pathway to the human food chain. As would be predicted, the research demonstrates that the chemical contamination of river sediment is not consistent worldwide. It was also found that often non-standardized approaches to sampling and sample preparation were reported in the published literature, which has implications for the credibility and replicability of research data, making comparison studies challenging and limiting the pool of data for use in data-driven decision-making. Finally, the authors have made five key policy-relevant, not policy-prescriptive recommendations for stakeholders and policymakers to address gaps in the information pool.

Despite the large number of scientific studies on the effects of antibiotics on soil microorganisms, little is known about the role played by soil organic matter (humus) in the interaction of antibiotics with microorganisms and plants, including the impacts on respiration and growth rate and the implications for nitrogen metabolism, which is an important factor in soil fertility The aim of this study was to analyze the effects of two widely used antibiotics, tetracycline and streptomycin, on microbiotic activity and plant growth in two soils with dissimilar organic carbon content, at the extremes of the fertility spectrum based on humus content. The study used humus-rich (Corg 5.4%) and humus-poor soils (Corg 1.5%) and measured basal respiration, substrate-induced respiration, nitric oxide emission, germination, and growth of white mustard 3 and 60 days after three progressively increasing doses of antibiotics were applied. Tetracycline was found to impair the ecological function of humus-rich soil by reducing denitrification and compromising soil microbial activity, while the effect of streptomycin on humus-poor soil was to reduce nitrification and soil fertility due to nitrogen escape. Both streptomycin and tetracycline increased the microbial biomass and suppressed the growth of white mustard seeds, which indicates an increase in the allelopathic activity of microorganisms in the soil conditions under the influence of antibiotics and their metabolites. Due to the low sorption of streptomycin in humus-poor soils, it poses a great danger to agricultural production, especially in areas of low fertility. In humus-rich soils, high concentrations of tetracycline caused numerous problems, including death of the crop plants. Thus, the effect of antibiotics as well as the more traditional soil pollutants, such as heavy metals, to a large extent, depends on the humus content of soils.

Please direct inquiries to the corresponding author (t.sizmur@reading.ac.uk).

Freshwater Gammarids are common leaf-shredding detritivores, and they usually feed on naturally conditioned organic material, in other words leaf litter that is characterised by an increased palatability, due to the action and presence of microorganisms (Chaumot et al. 2015; Cummins 1974: Maltby et al. 2002). Gammarus spp. are biologically omnivorous organisms, so they are involved in shredding leaf litter and are also prone to cannibalism, predation behaviour (Kelly et al. 2002) and coprophagy when juveniles (McCahon and Pascoe 1988). Gammarus spp. is a keystone species (Woodward et al. 2008), and it plays an important role in the decomposition of organic matter (Alonso et al. 2009; Bundschuh et al. 2013) and is also a noteworthy prey for fish and birds (Andrén and Eriksson Wiklund 2013; Blarer and Burkhardt-Holm 2016). Gammarids are considered to be fairly sensitive to different contaminants (Ashauer et al. 2010; Bloor et al. 2005; Felten et al. 2008a; Lahive et al. 2015; Kunz et al. 2010); in fact Amphipods have been reported to be one of the most sensitive orders to metals and organic compounds (Wogram and Liess 2001), which makes them representative test organisms for ecotoxicological studies and valid sentinel species for assessing water quality status (Garcia-Galan et al. 2017).

Around the world, many ambitious environmental conventions and regulations have been implemented over recent decades. Despite this, the environment is still deteriorating. An increase in the volume and diversity of chemicals is one of the main drivers of this deterioration, of which biodiversity loss is a telling indicator. In response to this situation, in October 2020, a chemicals strategy for sustainability (CSS) was published in the EU. The CSS is the first regional framework aiming to address chemical pollution in a holistic manner. The CSS covers the complete lifecycle of a chemical, including the design of better substances and remediation options, to remove chemicals from the environment. The strategy contains terms, such as a “toxic‐free environment,” for which no clear definition exists, potentially hampering the implementation of the CSS. In this paper, a definition for a “toxic‐free environment” is proposed on the basis of a survey and a discussion held at the 2020 SETAC Europe Annual Meeting. In addition, key issues that are absent from the CSS but are considered to be key for the realization of a toxic‐free environment are identified. To achieve the policy goals, it is recommended to align the definition of risk across the different chemical legislations, to establish a platform for open data and data sharing, and to increase the utility and use of novel scientific findings in policymaking, through the development of a strong science to regulation feedback mechanism and vice versa. The paper concludes that environmental scientists have the tools to address the key challenges presented in the CSS. However, an extra step is needed by both policymakers and scientists to develop methods, processes and tools, to increase the robustness and transparency of deliberation processes, and the utility of science. Integr Environ Assess Manag 2021;17:1105–1113. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

An investigation was undertaken to establish ifGammarus pulexandAsellus aquaticuspreferred a diet of unconditioned, artificially or naturally conditioned alder leaves (Alnus glutinosa). Standardised, 24 hourex situfeeding assays were undertaken with both species to determine their food preference. The results showed thatA. aquaticusate more leaf material compared toG. pulex(Z 23.909,P0.001) when exposed to all three test variables. Also, bothG. pulexandA. aquaticusdemonstrated a preference for naturally conditioned leaves compared to the other two variables, with unconditioned leaves proving the least popular food option for both macroinvertebrates (Z 18.803, ). However, both species ate varying amounts of all the leaf treatments (Z 136.399, ). Subsequently, the author outlined a feeding methodology for natural alder leaf conditioning that could be used during a laboratory breeding programme.

An investigation was undertaken to establish if Gammarus pulex and Asellus aquaticus preferred a diet of unconditioned, artificially or naturally conditioned alder leaves ( Alnus glutinosa ). Standardised, 24 hour ex situ feeding assays were undertaken with both species to determine their food preference. The results showed that A. aquaticus ate more leaf material compared to G. pulex (Z 23.909, P 0.001) when exposed to all three test variables. Also, both G. pulex and A. aquaticus demonstrated a preference for naturally conditioned leaves compared to the other two variables, with unconditioned leaves proving the least popular food option for both macroinvertebrates (Z 18.803, P < 0.001). However, both species ate varying amounts of all the leaf treatments (Z 136.399, P < 0.001). Subsequently, the author outlined a feeding methodology for natural alder leaf conditioning that could be used during a laboratory breeding programme.

espanolEste articulo se centra en el establecimiento de un programa de reproduccion para Gammarus pulex y Asellus aquaticus. Se capturaron ejemplares de estas dos especies de un rio no contaminado y se usaron como poblaciones iniciales para el programa. Estas poblaciones fundadoras se dejaron reproducir libremente y la descendencia resultante (F1, F2, F3, etc.) estuvo disponible para su uso en los test de toxicidad. Se discuten los detalles para el mantenimiento de las poblaciones reproductoras de estas especies asi como sus ciclos de vida EnglishThis paper outlines how to establish a standardised laboratory breeding programme for Gammarus pulex and Asellus aquaticus. Wild Gammarus pulex and Asellus aquaticus specimens were captured from an unpolluted river source and used as founder populations for the programme. The Gammarus pulex and Asellus aquaticus founder populations were permitted to breed randomly and the subsequent offspring (F1 , F2 and F3 generations etc.) were available as standardised test animals for mixed species aquatic toxicity tests. The husbandry required to maintain laboratory breeding populations of Gammarus pulex and Asellus aquaticus is outlined and the animals’ development cycles are discussed.

A specific landfill leachate that contained 1.036 mgl−1of 2-chlorobiphenyl was used in the study (255 mg l−1 COD and 133 mg l−1 BOD5). Three, 2-l semi-continuous batch reactors (SBRs) were used to simulate the treatment potential of this method on a small scale. Aerobic digestion effectively reduced the leachates COD concentration. Regardless of dilution, the leachates COD reached a <20 mg l−1 equilibrium after 96 h exposure to aerobic digestion, however, increasing the level of dilution accelerated the process. In untreated leachate, the LC50 for Asellus aquaticus was 57% v/v leachate in deionised water and 5% for Gammarus pulex (96 h, static LC50 tests without nutrition and oxygen depleting conditions). After being exposed to aerobic digestion, these values rose to 95% and 40%, respectively. Prolonged exposure to a 1:20 sub-lethal dilution of the aforementioned leachate has been previously shown to affect the breeding colony size of Asellus aquaticus and a 1:66 dilution influenced the fecundity of a Gammarus pulex population. After remediation by aerobic digestion, however, the population dynamics of both test species remained unaltered.

Mixed species feeding assays were undertaken with pollution sensitive (Gammarus pulex) and tolerant (Asellus aquaticus) macro-invertebrates during August 2003 and April 2004. The purpose of this study was to establish if a test animals' response is comparable during in-situ and ex-situ toxicity tests. Seven test sites were established along an undisclosed stream, which received leachate discharge from an unlined, disused UK landfill site. Sampling points A–B were upstream of the contamination, C was adjacent to the influx and D–G were downstream of the leachate discharge (at 100 m intervals). During the in-situ and ex-situ tests, 2-week-old male laboratory bred A. aquaticus and G. pulex were used as test animals. The animals were transplanted to the seven sampling points for the duration of the in-situ tests, whilst water samples from each site were returned to the laboratory for ex-situ testing. The results show that the animals' mortality and feeding rates followed similar trends during the in-situ and ex-situ tests, however, the animals' response was amplified during the in-situ tests. It was also observed that the effects were greater in April, compared to August that may be attributed to a higher frequency of rainfall during spring, which could have flushed a greater proportion of the contaminant load from the waste mass and as a consequence, higher levels of pollution may have leached into the stream from the landfill site. The study, therefore, concludes that in-situ toxicity tests are a more precise monitoring technique, in comparison to ex-situ assays.

In the past, many landfill sites were constructed and operated without engineering containment, and from which leachate is likely to arise over the next several decades. Landfill leachate can contain high concentrations of toxic substances, which may pose a threat to the surroundings. In the worst cases, leachates may seep through the underlying substrata causing contamination of groundwater, of surface water drains, and ultimately of the rivers into which they discharge. As a consequence, the diversity and species richness of benthic communities are often degraded.The chronic toxicity of a landfill leachate was investigated in this study, with respect to determining the 'environmentally safe' concentration in which the long term survival of an Asellus aquaticus population is assured. The leachate was from a disused site known to contain industrial wastes, and samples were collected from a surface drain. The leachate used in the toxicity tests had a 600 mg l(-1) BOD5 and 1200 mg l(-1) COD.Sub-lethal toxicity tests were carried out in leachate concentrations that were lower than the acute toxicity threshold of Asellus aquaticus. The toxicity was judged based on birth frequency and the final length of juveniles. Tests showed that even a dilution of 1:20 would influence the breeding colony size of Asellus. A 30 mg l(-1) COD concentration was judged to be the 'environmentally safe' leachate dilution in which the frequency of births and juvenile length (after 4 weeks of monitoring) would not be affected. At this concentration, the integrity of an Asellus population would be protected. (C) 2006 Elsevier B.V. All rights reserved.

In this study, a specific landfill leachate (1200 mgl−1 COD and 600 mgl−1 BOD5) was used to develop a standardised short-term acute and longer-term sublethal ex-situ toxicity testing programme, in order to determine the potential ecological implications of leaching contaminants reaching the water table. Bioassays were undertaken with juvenile Gammarus pulex and Asellus aquaticus macro-invertebrates. Preliminary acute test variables included static and static renewed flow rates for 96-h, starved and fed specimens, and aerobic and oxygen depleting conditions. However, regardless of any test variable, the lethal concentration (LC50) for A. aquaticus remained at 12.3% v/v leachate in deionised water, whilst that for G. pulex was only 1%. Sublethal toxicity was judged on the basis of frequency of births and the growth rate of newly born individuals. Tests showed that even a dilution as high as 1:66- would influence the fecundity of a Gammarus population, whilst a dilution of 1:20 would affect the size of an Asellus breeding colony.