Increased pharmaceutical usage has led to their widespread presence in aquatic environments, resulting in concerns regarding their potential environmental impacts. Antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) like citalopram, are frequently detected in European surface waters. Acute laboratory studies have demonstrated that citalopram can inhibit algal growth, immobilise Daphnia magna, and may result in foot detachment (i.e. the inability to adhere to a substrate) in snails. However, research on long-term citalopram exposure is scarce, and our understanding of its effects on aquatic community- and ecosystem-level is limited. Therefore, we investigated the impact of 13-week exposure to 0.01, 0.1, 1, 10 and 100 μg/L citalopram in outdoor freshwater mesocosms, focusing on water quality variables (i.e. pH, dissolved oxygen, electrical conductivity, temperature, algal chlorophyll-a, turbidity) and the structure of aquatic communities, with a special focus on mollusc foot detachment (Lymnaea stagnalis, Planorbis sp. and the total snail population). We found that environmentally relevant citalopram concentrations did not affect water quality variables, bacterial composition, zooplankton and macroinvertebrate communities. In contrast to expectations based on literature, snail foot detachment was not observed while the tested concentrations overlapped with the reported effect concentrations. This is in line with the absence of indirect adverse effects of foot detachment, such as population changes that could be the result of an increased vulnerability to predation or the inability to feed or reproduce. Reported sublethal effects in the literature, as found in laboratory studies, do not appear to lead to population- or community-level impacts in a semi-field experiment within the concentration range tested in this study. The experimental outcomes suggest that environmentally relevant concentrations of citalopram might not pose a threat to water quality variables, bacterial composition, zooplankton and macroinvertebrate communities, and snail foot detachment.

The co-occurrence of pesticides, pharmaceuticals, and MPs has resulted in combined toxicity and high risks to ecosystems and human health. However, understanding on the interactions among co-occurring pollutants in soils remains limited. This study focused on adsorption behaviour of a pesticide mixture (chlorpyrifos (CPF), pendimethalin (PDM) and pyraclostrobin (PCS)) in three soils (sandy soil (S1), loamy soil (S2), and silt soil (S3)) to examine the absorption behaviour of pesticides in the presence of the pharmaceutical compound albendazole (ALB) and starch-based microplastics (MPs). The results showed that ALB significantly decreased (p < 0.05) the adsorption of CPF, PDM, and PCS by 29 %–41 % in S1. The adsorption of CPF (+20 %) and PCS (+101 %) in S2 were significantly enhanced but PDM (−22 %) adsorption was inhibited by ALB. ALB also significantly (p < 0.05) promoted CPF and PCS adsorption in S3 by 39 % and 120 %, respectively, but did not change PDM adsorption. In soil-MP matrices, ALB significantly reduced the adsorption of CPF (−25 %), PDM (−26 %), and PCS (−21 %) in the S1-MP matrix, but no significant change in the S2 and S3-MP matrices was observed. Moreover, MPs significantly (p < 0.05) increased the adsorption of the pesticide mixture by 120–730 %, but reduced ALB adsorption by 11–24 % in soils. Further, regardless of ALB presence, correlation analysis suggested that Kd of pesticides showed positive correlations (p < 0.01) to soil organic matter, specific surface area, and clay content in soil matrices without MP-contamination, while no significant positive correlation between Kd of pesticides and soil properties was observed in soil-MPs matrices. This study indicates that co-occurring pollutants could alter the adsorption behaviour of pesticides in soil and thereby affect their bioavailability and mobility in the soil ecosystem. Further study is urgently needed to assess the ecotoxicity of co-occurring multi-contaminants, as well as their potential transport to other environmental compartments.

Since 2011, massive strandings of holopelagic Sargassum have occurred on the coasts of the Caribbean and of West Africa. Although open ocean Sargassum mats are oases of biodiversity, their stranding has a number of negative ecological, economic and health consequences. To limit these impacts, Sargassum needs to be collected as quickly as possible to avoid its decomposition, which requires accurate predictions of the date, location and abundance of the strandings. Two complementary approaches have been developed for this purpose: satellite remote sensing technique, to detect Sargassum aggregations, and modeling, to forecast Sargassum displacement and growth. The objective of this review is to provide a synthesis of the current knowledge related to Sargassum monitoring in the tropical Atlantic Ocean. To better understand the issues surrounding Sargassum and its monitoring, the first two parts are devoted to an overview of the ecology of the two most prevailing holopelagic Sargassum species, to the current issues related to their strandings, to the causes of their occurrence in the tropical Atlantic Ocean and to their seasonal and interannual variabilities. The methods used to detect Sargassum from satellite images and their limitations are examined. The transport and biogeochemical models developed for seasonal forecast and stranding predictions are described along with their limitations. As both detection and modeling rely on validation data to assess their accuracy, previous works providing in situ characterization of Sargassum are also reviewed here. The last part provides recommendations to further increase knowledge on holopelagic Sargassum and improve the predictions of their strandings.

Copper (Cu) and zinc (Zn) are common trace metal contaminants in marine environments that, despite their importance for the health of marine organisms, can be toxic. Recently, the stable isotopes of these elements have emerged as powerful tracers for studying their cycles. Thus, this review aims to connect urban and marine interfaces under a “land-sea continuum” framework to understand the complex sources, pathways, and transformations of Cu and Zn in urbanized coastal environments, a perspective currently lacking in the literature. Here, we briefly establish the sampling and analytical aspects of isotope measurement of these elements in the natural matrices of marine realms, providing a recent compilation of reference materials for analytical control. The principles of isotope fractionation are introduced and contextualized within coastal ecosystems. We summarize the isotopic signatures of major anthropogenic sources—including road-deposited sediments, non-exhaust traffic-related emissions, industrial waste, and metallurgical byproducts—and highlight the challenges of distinguishing them when isotopic ranges overlap. In parallel, natural baselines such as ores, soils, suspended particulate matter (SPM), and riverine inputs are also reviewed to contextualize environmental variability. The review examines how source isotope signatures evolve with further isotope fractionation during estuarine transport and transfer processes in the water-sediment-biota interface. Finally, this review also identifies future research directions to trace the sources, pathways, and sinks of these contaminants along the land-sea continuum, as well as the legacy and ongoing impact of urban metal pollution at catchment-to-coastal scales.

International audience | Polycyclic aromatic hydrocarbon (PAH) contamination in industrial soils poses significant environmental challenges, necessitating cost-effective bioremediation approaches like tree-based phytoremediation. However, the defence mechanisms and adaptability of trees to PAH exposure remain poorly understood, while the identification of molecular markers could help in the detection of toxicity symptoms. This study explores the molecular response of Populus canadensis to a phenanthrene (PHE) contamination gradient (from 100 to 2000 mg kg−1) using RNA-seq analysis of roots and leaves after 4 weeks of exposure. Both differentially expressed genes (DEGs) and DRomics, a dose–response tool, identified transcriptomic changes, with about 50% of deregulated genes responding significantly at a benchmark dose (i.e. minimal dose that produces a significant effect) below 400 mg PHE kg−1. The highest number of DEGs was found both at a low concentration (200 and 700 mg kg−1) and at the highest concentrations (1500–2000 mg kg−1) for both roots and leaves. Ethylene signalling genes were activated via ABA-independent pathways at low concentrations and ABA-dependent pathways at high concentrations. Across the gradient, responses to oxidative stress were triggered, including reactive oxygen species scavenging and phenylpropanoid biosynthesis, specifically at 1500–2000 mg kg−1. Additionally, PHE disrupted pathways related to plant responses to biotic stress. These findings revealed unexpected dose-dependent transcriptomic shifts, demonstrating poplar’s adaptive defence mechanisms against PHE toxicity.

Agricultural use of pesticides continues to rise globally. Argentina ranks fifth in use. While pesticides help yields, they also pose risks to human health and the environment. Indoor dust can present high pesticide concentrations, raising concerns about chronic exposure in non-farming households. Studies of pesticides in indoor dust are few worldwide. This pioneering study aimed to identify and/or quantify for the first time pesticide occurrence in indoor dust from urban residences in the Pampas Region, southeast of Buenos Aires Province, Argentina. Pesticide residues in indoor dust from 48 non-agricultural homes in the Pampas plain region were analysed. Study participants completed questionnaires on household demographics, pet ownership, pesticide use, gardening, and habits like leaving shoes outside. We detected 41 out of 49 targeted pesticides, including metabolites and banned compounds. Seven of the 49 tested are dual-use compounds (i.e. pesticide & biocide or veterinary applications). The synergist piperonyl butoxide, the dual-use imidacloprid, and “agricultural only” pesticides carbaryl, glyphosate, and atrazine were detected in all dust samples. Glyphosate, 2,4-D, atrazine, imidacloprid, carbaryl, tetramethrin, and piperonyl butoxide had maximum concentrations exceeding 1, 000 μg kg−1. Complex mixtures of up to 32 residues were found per sample. Questionnaire responses revealed that most participants brought shoes inside (60 %), almost all had pets (93 %), and 51 % had used flea repellents (mainly imidacloprid and fipronil). Approximately 48 % reported pesticide use in the past year, and 19 % reported exposure via their (non-farmer) jobs, e.g., via disinfection and weeding. These findings highlight the prevalence of pesticide residues in residential settings and the need for further research on long-term exposure and risks. Improved tracking of agricultural, household, and mixed-use pesticide applications is crucial, particularly in regions heavily reliant on agriculture.

The macroplastics (MaPs) and microplastics (MiPs) polluting agricultural soils raise great concerns. Unfortunately, scientists know little about the occurrence of MaPs/MiPs in soil among different farming systems. In this study, we analyzed MaPs/MiPs in soils (0–30 cm) collected from six different farming systems (wheat-maize rotations, cotton, vegetables, permanent orchards, greenhouses with and without mulching) in Quzhou county, the North China Plain, by using fluorescence microscope and micro-Fourier transform infrared spectroscopy. The results showed that the abundance of MaPs and MiPs ranged from 0.2 to 46.8 kg ha−1, and 4.1 × 103–3.7 × 104 items kg−1, respectively. The prominent colors of the MaPs were white and black. The predominant shape, size and chemical composition of soil MiPs were fragments (45–62%), <1 mm (98–99%), and polyethylene (38–43%), respectively. MaPs were mainly detected in the 0–10 cm soil layer. MiP abundance in the 0–10 cm soil layer was significantly higher than that in the 20–30 cm soil layers among different farming systems, except for the fields with wheat-maize rotations and permanent orchards (p < 0.05). Overall, cotton fields showed the highest MaP and MiP abundance, followed by vegetable fields and orchards. Redundancy analysis revealed that tillage practices and plastic film management greatly influence the size distribution of MiPs. A strong negative correlation between large-sized plastic fractions (0.2–1 mm) and tillage frequency was tested while the years of application of plastic films and the abundance of plastic residues showed a strong positive correlation with small-sized plastic fractions (<0.2 mm). Our findings conclude that agricultural mulch films are an important source of MaPs and MiPs in agricultural soil and distributions are strongly influenced by agricultural management practices and farming systems. Further studies should take farming systems and farming practices into account, thereby exploring the potential mechanisms of plastic fragmentation and granularization in agricultural soil.

Water quality is under threat due to the presence of pathogenic and antibiotic-resistant bacteria. Escherichia coli (E. coli) serves as an indicator of faecal contamination and the potential presence of other harmful pathogens. Understanding E. coli concentrations helps in assessing the overall health risks associated with waterborne diseases and developing effective water management strategies. Therefore, we developed the first large-scale model, GloWPa-Ecoli C1 to simulate E. coli loads and concentrations in rivers and apply this model to China. The model provides the first comprehensive overview of microbial water quality across China's rivers. The model simulates E. coli concentrations in 2020 to range from 10−1.2 to 106.3 CFU/L, with 45.6 %–78.1 % of rivers exhibiting poor microbial water quality. Major hotspots of E. coli pollution are Haihe, Huaihe and Pearl River Basins. Direct discharge of human faecal waste contributes 80.2 % of the total E. coli load, while directly discharged livestock waste accounts for 13.1 %. To mitigate E. coli pollution in rivers in China, we recommend increasing human faecal waste collection rates, expanding wastewater treatment plant (WWTP) coverage, phasing out primary treatment WWTPs and eliminating direct livestock faecal waste discharge, particularly from smallholder farms. The study underscores the urgent need to improve microbial water quality in China's rivers. The findings provide actionable insights to inform policy development aimed at safeguarding water quality and public health. Furthermore, the modelling approach is applicable to other regions and microorganisms, offering a foundation for developing models to address antibiotic-resistant bacteria and other emerging water quality challenges.