This study was conducted in order to assess the level of heavy metals in the water, soil, and tissues of Pomacea canaliculata from Lake Dakong Napo, Esperanza, Philippines as well as identify the histopathological alterations in the gonads and muscles of the snail. Heavy metals were detected using Atomic Absorption Spectrometry and slides for histological studies were prepared using histological routine procedure. Results revealed that in sediments Cr (174.67±62 mg/L) and Ni (269.33±17.56 mg/L) were above from the recommended safe limits of the international standards, US EPA (≤25) and FAO (≤50) while concentrations of Pb (16.35± 0.58 mg/L), Cd (5±1.42 mg/L), and Cr (1±0 mg/L) in water were above from the recommended safe limits of the national standards, DAO (≤0.05; ≤0.01; ≤0.05). These heavy metals were below the permissible limits in the gonads and muscles of P. canaliculata however, alterations in the tissues of the snail are evident suggesting that these heavy metals and other environmental stressors are negatively affecting the organisms inhabiting the lake.

The biotoxins can enter the marine food chain, and, accordingly, seafood consumers are also at risk of ingesting toxins from contaminated aquatic animals. Hormozgan Province in the north of Persian Gulf is an area with high industrial and urbanization rising rate. In the present work, the aim was to identify the okadaic acid and domoic acid producers in the coastal waters and to investigate on their accumulated concentrations in edible bivalves in order to assess the consumer’s health risk. Water samples were collected during winter 2018 and summer 2019 from one blank and four stations facing industrial and municipal effluents. Four species of edible bivalves were collected from coastal lines of Hormozgan province, at the lowest tide time. The concentrations of toxins were determined by indirect competitive ELISA method. Pseudonitzschia delicatissima, Nitzschia punges and Nitzschia seriata in the production of domoic acid and Dinophysis caudate, Prorocentrum Lima and Ceratium tripos in the production of okadaic acid were identified. The okadaic acid concentrations ranged from 59.8 ± 2.38 to 121.96 ± 28.25 µg/kg, ranging from 0.85 to 83.59 ± 38.72 for Domoic acid. Among the studied bivalves, Pinctada radiate contained the maximum concentrations of measured toxins. For the first time at Hormozgan Province, the consumption guidelines for domoic and okadaic acid were calculated. The human health risk assessment showed that at present time, the algal consumers from Hormozgan province are not at risk of domoic and okadaic acid toxins.

Phytoremediation is an eco-friendly method for removal of pollutants, which can be relied upon as a sustainable technology, if implemented under optimum conditions of plant growth. The effectiveness of water hyacinth, a topical weed, for the removal of Zinc (Zn) and Chromium (Cr) ions from aqueous solutions has been presented in this article. The potential of this plant in removing metals by phytoremediation was explored under various environmental factors such as pH, salinity, metal concentrations, available nutrients, and so on. The efficiency of metal removal was observed by varying the different parameters. It was found that the maximum removal of metals occurred at a neutral pH, low amount of salinity, lower metal ion concentrations, and lack of nutrients. The stress induced in a plant by metal absorption was visible from the health and growth pattern of the plants. The stress on water hyacinth due to metals was also assessed, by observing the changes in its chlorophyll and protein content.

In this study, a strain of lactic acid bacteria Streptococcus salivarius was studied for its capacity to remove hexavalent chromium (Cr (VI)) from a liquid medium and to form biofilm. Both properties are useful for using the strain in bioremediation of metal-contaminated effluents. For biofilm formation capacity, three methods were used: the tube method (TM), the Congo red agar method (CRA) and adherence to polystyrene tissue culture plate method (TCP). S. salivarius, showed a positive-biofilm and a correlation between the three methods was noted. The bacterial surface hydrophobicity was studied using the microbial adhesion to solvents method (MATS). On AISI-316 L stainless steel, the strain with a hydrophobic surface showed a good adhesion on this support after 18 h incubation. The colonization of the supports and the biofilms formation by the bacterial cell was observed using scanning electron microscopy (SEM). The minimum inhibitory concentration (MIC) of Cr(VI) on S. salivarius was determined on MRS broth, it was relatively high and equal to 400mg/l. In addition, it displayed a remarkable capacity to reduce Cr(VI) concentration on the liquid medium containing initially 50 mg/l of Cr(VI) ; the percent removal rate was equal to approximately 42% after 72 h of incubation at 37 °C. In addition to its GRAS status, the obtained results suggested that S. salivarius could be successfully used in Cr(VI) bioremediation.

Urban horticulture is of growing importance in developing and developed countries around the world; however, contamination of urban horticultural products can exceed the precautionary values, posing significant human health risks due to dietary exposure to high levels of the pollutants. In this study, samples of rhizosphere soil and corresponding vegetables have been collected from an urban garden in Ilorin, Nigeria, to assess the contamination level of trace metals as well as the health risk, associated with dietary intake of contaminated vegetables, in adult sub-population. The range of Cu, Pb, and Cd in garden topsoil was 14.0-52.50, 33.00-121.40, and 1.00-4.50 mg/kg, respectively. The metals sources were both anthropogenic and lithogenous, though the long-term accumulation of trace metals in the soil led to significant soil-plant transfer as evident in the levels of metals in some of the vegetables. The estimated daily intakes (EDI) of Cu and Pb through vegetable consumption were far below the recommended tolerable daily intakes (TDI) and the hazard quotient (HQ) values were within the safe zone for the adult population. In contrast, the EDI of Cd for the vegetables was several folds greater than the TDI, thus greatly contributing to a high hazard index (HI>1.0), observed in all vegetables. Therefore, risk assessment of trace metal ingestion through consumption of the vegetables in the adult sub-population depicts serious health hazards with Cd, mainly contributing to vegetable contamination in the studied area.

Large quantities of chlordecone-based insecticides were produced and used throughout the world. One of its most important uses was to control the damage caused by Cosmopolites sordidus in banana-growing regions. In the islands of Martinique and Guadeloupe, 18,000 ha of farmland are potentially contaminated. Despite the key role played by soil macrofauna in agroecosystems, there are currently no data on their contamination. The aim of this study was to explore the fate of chlordecone (CLD) and its transfer to different organisms of the soil food web. Seven species of invertebrates representing different taxonomic groups and trophic levels of the soil communities of Martinique were targeted and collected in six experimental banana fields, with a level of contamination within a range of values classically observed. Soil samples and macrofauna from the study sites were analysed for CLD and chlordecol (CLDOH) its main transformation product. The contamination of the soil fauna were related to δ15N (trophic level), proportion of soil ingestion (diet) and types of epidermis (mucus or exoskeleton) in order to study the different mechanisms of macrofauna contamination. Presence of CLD and CLDOH could be quantified in all the soil organisms from contaminated fields. Results showed a significant relationship between the CLD contamination of detritivorous and the ash content of their faeces, suggesting that soil ingestion was the main contamination pathway. In contrast, the exoskeleton-bearing diplopod Trigoniulus coralinus and the soft-bodied earthworm Eudrilus eugeniae, both detritivores with a comparable diet, had similar contamination levels, suggesting that the type of tegument has little influence on bioaccumulation. At the scale of the entire trophic network, a significant relationship was uncovered between δ15N values and CLD contamination of the fauna, therefore providing some in situ evidence for a bioamplification process along the soil food chain.

Organic chemical pollutants associated with microplastic (MP) may represent an alternative exposure route for these chemicals to marine biota. However, the bioavailability of MP-sorbed organic pollutants under conditions where co-exposure occurs from the same compounds dissolved in the water phase has rarely been studied experimentally, especially where pollutant concentrations in the two phases are well characterized. Importantly, higher concentrations of organic pollutants on ingested MP may be less bioavailable to aquatic organisms than the same chemicals present in dissolved form in the surrounding water. In the current study, the sorption kinetics of two model polycyclic aromatic hydrocarbons (PAHs; fluoranthene and phenanthrene) to MP particles in natural seawater at 10 and 20 °C were studied and the bioavailability of MP-sorbed PAHs to marine copepods investigated. Polyethylene (PE) and polystyrene (PS) microbeads with mean diameters ranging from 10-200 µm were used to identify the role of MP polymer type and size on sorption mechanisms. Additionally, temperature dependence of sorption was investigated. Results indicated that adsorption dominated at lower temperatures and for smaller MP (10 µm), while absorption was the prevailing process for larger MP (100 µm). Monolayer sorption dominated at lower PAH concentrations, while multilayer sorption dominated at higher concentrations. PE particles representing ingestible (10 µm) and non-ingestible (100 µm) MP for the marine copepod species Acartia tonsa and Calanus finmarchicus were used to investigate the availability and toxicity of MP-sorbed PAHs. Studies were conducted under co-exposure conditions where the PAHs were also present in the dissolved phase (Cfree), thereby representing more environmentally relevant exposure scenarios. Cfree reduction through MP sorption was reflected in a corresponding reduction of lethality and bioaccumulation, with no difference observed between ingestible and non-ingestible MP. This indicates that only free dissolved PAHs are significantly bioavailable to copepods under co-exposure conditions with MP-sorbed PAHs. | publishedVersion

It has been proposed that non-protein thiols and organic acids play a major role in cadmium phytoavailability and distribution in plants. In the Cd-hyperaccumulator Solanum nigrum and non-accumulator Solanum melongena, the role of these organic ligands in the accumulation and detoxification mechanisms of Cd are debated. In this study, we used X-ray absorption spectroscopy to investigate Cd speciation in these plants (roots, stem, leaves) and in the soils used for their culture to unravel the plants responses to Cd exposure. The results show that Cd in the 100 mg.kg-1 Cd-doped clayey loam soil is sorbed onto iron oxyhydroxides. In both S. nigrum and S. melongena, Cd in roots and fresh leaves is mainly bound to thiol ligands, with a small contribution of inorganic S ligands in S. nigrum leaves. We interpret the Cd binding to sulfur ligands as detoxification mechanisms, possibly involving the sequestration of Cd complexed with glutathione or phytochelatins in the plant vacuoles. In the stems, results show an increase binding of Cd to -O ligands (>50% for S. nigrum). We suggest that Cd is partly complexed by organic acids for transportation in the sap.

Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physicochemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation.

Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data.