International audience | Heterostructured nanomaterials exhibit pronounced potential in environmental science, including the water purification, pollutant monitoring, and environmental remediation. Especially, their application through advanced oxidation processes has been found capable and adaptable in waste water treatment. In semiconductor photocatalysts, metal sulfides are the leading materials. However, for further modifications, the progresses on specific materials need to be overviewed. Among metal sulfides, nickel sulfides are the emerging semiconductors due to relatively narrow band gaps, high thermal and chemical stability, and cost effectiveness. The aim of the present review is to conduct a thorough analysis and summary of recent progress in the application of nickel sulfide-based heterostructures in water decontamination. Initially, the review introduces the emerging needs of the materials for environment following the characteristics features of metal sulfides with emphasis on nickel sulfides. Subsequently, synthesis strategies and structural properties of nickel sulfide (NiS and NiS2)-based photocatalysts are discussed. Herein, controlled synthesis procedures to influence their active structure, compositions, shape, and size for the enhanced photocatalytic performances are also considered. Furthermore, there is discussion on heterostructures formed by metal modification, metal oxides, and carbon hybridized nanocomposites. In the continuation, the modified characteristics are investigated which favors the photocatalytic processes for degradation of organic contami-nations in water. The overall study highlights significant improvements in degradation efficiency of hetero-interfaced NiS and NiS2 photocatalysts towards organics that are comparable to expensive noble-metal photocatalysts. Finally, we also added a little on prospects for future advancement of nickel sulfide-based photocatalysts for applications in sustainable environmental remediation.

International audience | 4-hydroxyphenylpyruvate dioxygenase (HPPD) is the molecular target of β-triketone herbicides in plants. This enzyme, involved in the tyrosine pathway, is also present in a wide range of living organisms, including microorganisms. Previous studies, focusing on a few strains and using high herbicide concentrations, showed that β-triketones are able to inhibit microbial HPPD. Here, we measured the effect of agronomical doses of β-triketone herbicides on soil bacterial strains. The HPPD activity of six bacterial strains was tested with 1× or 10× the recommended field dose of the herbicide sulcotrione. The selected strains were tested with 0.01× to 15× the recommended field dose of sulcotrione, mesotrione, and tembotrione. Molecular docking was also used to measure and model the binding mode of the three herbicides with the different bacterial HPPD. Our results show that responses to herbicides are strain-dependent with Pseudomonas fluorescens F113 HPPD activity not inhibited by any of the herbicide tested, when all three β-triketone herbicides inhibited HPPD in Bacillus cereus ATCC14579 and Shewanella oneidensis MR-1. These responses are also molecule-dependent with tembotrione harboring the strongest inhibitory effect. Molecular docking also reveals different binding potentials. This is the first time that the inhibitory effect of β-triketone herbicides is tested on environmental strains at agronomical doses, showing a potential effect of these molecules on the HPPD enzymatic activity of non-target microorganisms. The whole-cell assay developed in this study, coupled with molecular docking analysis, appears as an interesting way to have a first idea of the effect of herbicides on microbial communities, prior to setting up microcosm or even field experiments. This methodology could then largely be applied to other family of pesticides also targeting an enzyme present in microorganisms.

Plastics in rivers and lakes have direct local impact, and may also reach the world's oceans. Monitoring river plastic pollution is therefore key to quantify, understand and reduce plastics in all aquatic ecosystems. The lack of harmonization between ongoing monitoring efforts compromises the direct comparison and combination of available data. The United Nations Environment Programme (UNEP) launched guidelines on freshwater plastic monitoring, to provide a starting point for practitioners and scientists towards harmonized data collection, analysis, and reporting. We developed a five-step workflow to support to design effective plastic monitoring strategies. The workflow was applied to three rivers (Rhine, Mekong and Odaw) across relevant gradients, including geography, hydrology, and plastic pollution levels. We show that despite the simplicity of the selected methods and the limited duration of the data collection, our harmonized approach provides crucial insights in the state of plastic pollution in very different river basins globally.

Multirotor drones can be efficiently used to monitor macro-litter in coastal and riverine environments. Litter on beaches, dunes and riverbanks, along with floating litter on coastal and river waters, can be spotted and mapped from aerial drone images. Items detection and classification are prone to image resolution, which is expressed in terms of Ground Sampling Distance (GSD). The GSD is determined by drone flight altitude and camera properties. This paper investigates what is a suitable GSD value for litter survey. Drone flight altitude and camera setup should be chosen to obtain a GSD between 0.5 cm/px and 1.25 cm/px. Within this range, the lowest GSD allows litter categorization and classification, whereas the highest value should be adopted for a coarser litter census. In the vision of drawing up a global protocol for drone-based litter surveys, this work sets the ground for homogenizing data collection and litter assessments.

Structurally complex habitats, such as mangrove forests, allow for rich assemblages of species that benefit from the provided space, volume and substrate. Changes in habitat complexity can affect species abundance, diversity and resilience. In this study, we explored the effects of habitat complexity on food web networks in four developmental stages of mangrove forests with differing structural complexities: climax > degrading > colonizing > bare, by analyzing food web structure, stable isotopes and habitat complexity. We found that food webs became gradually more biodiverse (species richness: +119 %), complex (link density: +39 %), and robust (connectance: −35 %) in climax versus bare stages with increasing complexity of the mangrove forest (i.e., number of trees, leaf cover, and pneumatophore densities). This study shows that habitat complexity drives food web network structure in dynamic mangrove forests. We recommend restoration practitioners to use this food web network approach to quantify habitat restoration successes complementary to traditional biodiversity metrics.

Structurally complex habitats, such as mangrove forests, allow for rich assemblages of species that benefit from the provided space, volume and substrate. Changes in habitat complexity can affect species abundance, diversity and resilience. In this study, we explored the effects of habitat complexity on food web networks in four developmental stages of mangrove forests with differing structural complexities: climax > degrading > colonizing > bare, by analyzing food web structure, stable isotopes and habitat complexity. We found that food webs became gradually more biodiverse (species richness: +119 %), complex (link density: +39 %), and robust (connectance: −35 %) in climax versus bare stages with increasing complexity of the mangrove forest (i.e., number of trees, leaf cover, and pneumatophore densities). This study shows that habitat complexity drives food web network structure in dynamic mangrove forests. We recommend restoration practitioners to use this food web network approach to quantify habitat restoration successes complementary to traditional biodiversity metrics.

Plastics in rivers and lakes have direct local impact, and may also reach the world's oceans. Monitoring river plastic pollution is therefore key to quantify, understand and reduce plastics in all aquatic ecosystems. The lack of harmonization between ongoing monitoring efforts compromises the direct comparison and combination of available data. The United Nations Environment Programme (UNEP) launched guidelines on freshwater plastic monitoring, to provide a starting point for practitioners and scientists towards harmonized data collection, analysis, and reporting. We developed a five-step workflow to support to design effective plastic monitoring strategies. The workflow was applied to three rivers (Rhine, Mekong and Odaw) across relevant gradients, including geography, hydrology, and plastic pollution levels. We show that despite the simplicity of the selected methods and the limited duration of the data collection, our harmonized approach provides crucial insights in the state of plastic pollution in very different river basins globally.

Multirotor drones can be efficiently used to monitor macro-litter in coastal and riverine environments. Litter on beaches, dunes and riverbanks, along with floating litter on coastal and river waters, can be spotted and mapped from aerial drone images. Items detection and classification are prone to image resolution, which is expressed in terms of Ground Sampling Distance (GSD). The GSD is determined by drone flight altitude and camera properties. This paper investigates what is a suitable GSD value for litter survey. Drone flight altitude and camera setup should be chosen to obtain a GSD between 0.5 cm/px and 1.25 cm/px. Within this range, the lowest GSD allows litter categorization and classification, whereas the highest value should be adopted for a coarser litter census. In the vision of drawing up a global protocol for drone-based litter surveys, this work sets the ground for homogenizing data collection and litter assessments.

Levels of 14 trace elements (Al, Ti, V, Cr, Mn, Co, Ni, Zn, As, Se, Cd, Sn, Hg, and Pb) and 5 arsenic species (arsenite/As(III), arsenate/As(V), monomethylarsonic acid/MA, dimethylarsinic acid/DMA, and arsenobetaine/AsB) were assessed in the gonads of sea urchin samples (Paracentrotus lividus) from North-West Mediterranean Sea (French coast). The samples were collected from 13 sites characterized by different types and levels of chemical contamination. Trace elements levels were measured by inductively coupled plasma-mass spectrometry (ICP-MS) following microwave (acid) digestion in a closed system, whereas As speciation analysis was carried out by ion-exchange liquid chromatography coupled with ICP-MS after microwave-assisted extraction. High levels of trace elements were found in sea urchins sampled from Corsica whereas the samples from Théoule were found to be the least contaminated. From all the analyzed urchin samples, none showed Cd, Hg, or Pb concentrations above the regulatory levels set by the European Community (EC) No. 1881/2006 for seafood or bivalve mollusks. Regarding arsenic speciation, AsB was confirmed to be the predominant species. Inorganic As (As(III) + As(V)) was mainly constituted by As(III), which was quantified in all samples. Methylated As forms (MA and DMA) represent 9 to 23% of the total As.

Plasticizers are compounds often involved in the manufacturing of plastic products. Nevertheless, the ageing of the latter generates plasticizers that generally end up in the marine environment. In fact, marine pollution by phthalate acid esters (PAEs) and their alternatives has become an environmental and health issue of serious concern, as they are largely and ubiquitously present in the environment and aquatic organisms. In the present study, four PAEs, such as diethyl phthalate (DEP), diisobutyl phthalate (DiBP), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP), and one non-phthalate plasticizer (NPP), namely di-2-ethylhexyl terephthalate (DEHT), are wanted in different marine compartments from the coast of Mahdia in Tunisia such as sediment, seagrass, and mussel. The most abundant and frequently detected congener was DEHT at the concentrations reached 1.181 mg/kg in the sediment, 1.121 mg/kg in the seagrass, and 1.86 mg/kg in the mussel. This result indicates that the DEHT could emerge through the food chain and therefore bioaccumulate in marine compartments. In addition, we noticed that the seasonal variations of plasticizers were seriously affected by environmental factors including industrial and urban discharges.