[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | International audience | Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial substrates placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatization phase of 7 days, were exposed to alachlor at 10 and 30 µg L-1 for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The structural responses of bacterial and diatom communities and diatom were difficult to distinguish from changes linked to the microcosm incubation period. Phototrophic biofilms from site S exposed at 30 µg L-1 alachlor were characterised by an increase of Achnanthidium minutissimum (K-z.) Czarnecki abundance, as well as a higher proportion of abnormal frustules. Thus, phototrophic biofilms with different histories, exhibited different responses to alachlor exposure demonstrating the importance of growth environment. These observations also confirm the problem of distinguishing changes induced by the stress of pesticide toxicity from temporal evolution of the community in the microcosm.

Coral reefs are amongst the most biodiverse ecosystems on earth, but are significantly impacted by agricultural runoff. Despite herbicides being commonly detected in coastal waters, the possibility of herbicide accumulation in coral reef species has largely been overlooked. We investigate the accumulation of several herbicides in five species of coral reef invertebrates collected from ten sites along the Maputaland coast, South Africa. Multiple herbicide residues were detected in 95% of the samples, with total average concentrations across sites ranging between 25.2 ng g⁻¹ to 51.3 ng g⁻¹ dw. Acetochlor, alachlor and hexazinone were the predominant herbicides detected at all sites, with atrazine and simazine detected less frequently. Significant interactive effects were detected between sites nested in reef complex crossed with species, based on multiple and total herbicide concentrations. In general, multivariate herbicide concentrations varied significantly between species within and across most sites. Contrastingly, the concentrations of the different herbicides and that of total herbicide did not differ between conspecifics at most sites nested in their respective reef complexes. On average, highest total herbicide concentrations were measured in soft coral (Sarcophyton glaucum; 90.4 ± 60 ng g⁻¹ and Sinularia gravis; 42.7 ± 25 ng g⁻¹) and sponge (Theonela swinhoei; 39.0 ± 40 ng g⁻¹) species, while significantly lower concentrations were detected in hard corals (Echinopora hirsutissima; 10.5 ± 5.9 ng g⁻¹ and Acropora austera; 5.20 ± 4.5 ng g⁻¹) at most sites. Agricultural runoff entering the ocean via the uMfolozi-St Lucia Estuary and Maputo Bay are likely sources of herbicide contamination to coral reefs in the region. There is an urgent need to assess the long-term effects of herbicide exposure on coral reef communities.

Several environmental pollutants, including pesticides, herbicides and persistent organic pollutants play an important role in the development of chronic diseases. However, most studies have examined environmental pollutants toxicity in target organisms or using a specific toxicological test, losing the real effect throughout the ecosystem. In this sense an integrative environmental risk of pollutants assessment, using different model organisms is necessary to predict the real impact in the ecosystem and implications for target and non-target organisms.The objective of this study was to use alachlor, a chloroacetanilide herbicide responsible for chronic toxicity, to understand its impact in target and non-target organisms and at different levels of biological organization by using several model organisms, including membranes of dipalmitoylphosphatidylcholine (DPPC), rat liver mitochondria, bacterial (Bacillus stearothermophilus), plant (Lemna gibba) and mammalian cell lines (HeLa and neuro2a).Our results demonstrated that alachlor strongly interacted with membranes of DPPC and interfered with mitochondrial bioenergetics by reducing the respiratory control ratio and the transmembrane potential. Moreover, alachlor also decreased the growth of B. stearothermophilus and its respiratory activity, as well as decreased the viability of both mammalian cell lines. The values of TC₅₀ increased in the following order: Lemna gibba < neuro2a < HeLa cells < Bacillus stearothermophilus. Together, the results suggest that biological membranes constitute a putative target for the toxic action of this lipophilic herbicide and point out the risks of its dissemination on environment, compromising ecosystem equilibrium and human health.

The presence of organic pollutants in the aquatic environment, usually found at trace concentrations (i.e., between ng L−1 and μg L−1 or even lower, known as micropollutants), has been highlighted in recent decades as a worldwide environmental concern due to their difficult elimination by conventional water and wastewater treatment processes. The relevant information on constructed wetlands (CWs) and their application for the removal of a specific group of pollutants, 41 organic priority substances/classes of substances (PSs) and 8 certain other substances with environmental quality standards (EQS) listed in Directive 2013/39/EU as well as 17 contaminants of emerging concern (CECs) of the Watch List of Decision 2015/495/EU, is herein reviewed. Studies were found for 24 PSs and 2 other substances with EQS: octylphenol, nonylphenol, perfluorooctane sulfonic acid, di(2-ethylhexyl)phthalate, trichloromethane, dichloromethane, 1,2-dichloroethane, pentachlorobenzene, benzene, polychlorinated dibenzo-p-dioxins, naphthalene, fluoranthene, trifluralin, alachlor, isoproturon, diuron, tributyltin compounds, simazine, atrazine, chlorpyrifos (chlorpyrifos-ethyl), chlorfenvinphos, hexachlorobenzene, pentachlorophenol, endosulfan, dichlorodiphenyltrichloroethane (or DDT) and dieldrin. A few reports were also published for 8 CECs: imidacloprid, erythromycin, clarithromycin, azithromycin, diclofenac, estrone, 17-beta-estradiol and 17-alpha-ethinylestradiol. No references were found for the other 17 PSs, 6 certain other substances with EQS and 9 CECs listed in EU legislation.

Solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS) was used to analyze two triazine (atrazine and simazine) and three chloroacetamide herbicides (acetochlor, alachlor, and metolachlor) in water samples from a midwest US agricultural drainage ditch for two growing seasons. The effects of salt concentration, sample volume, extraction time, and injection time on extraction efficiency using a 100-μm polydimethylsiloxane-coated fiber were investigated. By optimizing these parameters, ditch water detection limits of 0.5 μg L-1 simazine and 0.25 μg L-1 atrazine, acetochlor, alachlor, and metolachlor were achieved. The optimum salt concentration was found to be 83% NaCl, while sample volume (10 or 20 mL) negligibly affected analyte peak areas. The optimum extraction time was 40 min, and the optimum injection time was 15 min. Results indicated that atrazine levels in the ditch water exceeded the US maximum contaminant level for drinking water 12% of the time, and atrazine was the most frequently detected among studied analytes. Solid-phase microextraction methods were successfully developed to quantify low levels of herbicides in tile-fed drain water by gas chromatography-mass spectrometry.

This work provides the first spatial distribution report of micropollutants (MPs) in the entire Portuguese coast, comprising the ocean shore (sea water, SW) and whenever possible the nearest river discharging on it (estuarine water, EW). This surface water monitoring programme aimed to assess the spatial distribution of 37 MPs with a wide chemical nature, including some substances prioritized by the European Union Directive 39/2013/EU and contaminants of emerging concern targeted in the Watch List of Decisions 495/2015/EU and 840/2018/EU. The risk quotients were estimated in each sampling point for the detected MPs. High concentrations of diclofenac, tramadol and carbamazepine were determined, the latter with medium to high risk for algae. Some pharmaceuticals and perfluorooctanesulfonic acid (PFOS) were broadly distributed, maybe due to the direct discharge into the sea. Atrazine and alachlor were found in the majority of the samples, with alachlor levels often considered as medium to high risk.

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 – 27.4, and 83 – 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

In this work, we examined the effect of two different organic wastes, composted sheep manure and coir, on the sorption, persistence, and mobility of three pesticides (alachlor, chlorfenvinphos, and chlorpyrifos) included as priority substances in European Directive 2013/39/EU. With this aim, leaching studies were conducted using disturbed soil columns filled with a typical agricultural soil (hipercalcic calcisol) from a semiarid area (southeastern Spain) to determine their potential for groundwater pollution. The three compounds were found in leachates of unamended soil although in different proportions: 53% (alachlor), 9% (chlorfenvinphos), and 6% (chlorpiryfos). The addition of organic wastes significantly increased the sorption of the studied pesticides. As a consequence, the half-lives of the studied pesticides were higher in amended than in unamended soils. A marked reduction of the amount recovered in leachates was observed in the amended soils, except for chlorpiryfos, whose recoveries barely changed. According to their potential groundwater pollution calculated as the groundwater ubiquity score (GUS) index, alachlor and chlorfenvinphos show medium leachability while chlorpiryfos is unlikely to leach.

The present study evaluated the short-term toxicity of seven selected pesticides: four insecticides (chlorpyrifos, dieldrin, diazinon and pirimiphos-methyl) and three herbicides (diuron, alachlor and atrazine). With this aim, a standard toxicity test with the highly sensitive early life stages (ELS) of a marine fish was used. The turbot, Psetta maxima, is abundant in shallow estuarine and costal habitats and is currently the most commonly cultivated fish species in Galicia, NW Spain. According to the turbot ELS test results, chlorpyrifos was the most toxic pesticide tested for both embryos and larvae and was followed in order of decreasing toxicity by dieldrin, pirimiphos-methyl, diazinon, alachlor, atrazine and diuron. Larvae were more sensitive than embryos to the seven pesticides. The median lethal concentrations of the selected pesticides during a 48- and a 96-h exposure for turbot embryos and larvae were, respectively (in micrograms per litre): chlorpyrifos, 116.6 and 94.65; dieldrin, 146 and 97; pirimiphos-methyl, 560 and 452; diazinon, 1,837 and 1,230; alachlor, 2,177 and 2,233; diuron, 10,076 and 7,826; and atrazine, 11,873 and 9,957. According to their acute toxicity, the insecticides were more toxic than the herbicides. Furthermore, all insecticides and herbicides appear to be teratogenic to turbot ELS.