Diet is an important route of mercury (Hg) uptake in marine organisms. Trophic transfer of Hg throughout the food webs may be influenced by various factors, including diet and Hg speciation. Bivalves such as oysters are widely used as bioindicators of trace element pollution such as Hg. Nevertheless, our current knowledge regarding their ability to accumulate Hg from their diet is mainly based on experiments performed using phytoplankton. In their natural environment, oysters feed on a variety of food items including ciliates, detritus, in addition to phytoplankton. The present study aimed at examining the influence of diet composition on the trophic transfer of inorganic Hg (iHg) and methylmercury (MeHg) in the Pacific cupped oyster Crassostrea gigas. The pulse-chase feeding method was used with two radiolabeled food items: a heterotrophic protist (Uronema marinum) and a phytoplanktonic diatom (Thalassiosira pseudonana). Depuration of dietary Hg in the oysters was followed for 50 d. Kinetic parameters including assimilation efficiency (AE) and efflux rate constant (kₑ) were calculated. Our results showed that oysters fed on ciliates assimilated 96 ± 1% and 31 ± 2% of the ingested MeHg and iHg, respectively whereas these elements were similarly assimilated in the oysters fed on phytoplankton (78 ± 3% and 86 ± 4% for MeHg and iHg, respectively). Mercury assimilation in oyster is thus diet dependent (significant differences in AE, p < 0.05), metal species-dependent and likely resulting from variations in Hg bioavailability in the two food items tested and a gut passage time-dependent of the ingested matrix.

Cadmium (Cd) is a well-characterized toxic heavy metal which could cause severe kidney injury. However, currently the knowledge of Cd toxicity towards kidney is still insufficient. Our previous data has identified that MT1DP (metallothionein 1D pseudogene) could promote Cd-induced detrimental effects on hepatocytes. Herein, we further found that MT1DP was also an important intermediate to aggravate Cd-induced nephrotoxicity. Through analyzing the data of 100 residents from Cd-contaminated area in Southern China, we found that the blood MT1DP levels correlated to the urine Cd content and the extent of nephrotoxicity. Although MT1DP was predominantly induced by hepatocytes in the liver, liver-secreted MT1DP was found to be packaged into extracellular cargoes: exosomes, by which MT1DP was delivered into circulation and thereafter targeted kidney cells. Furthermore, exosome-laden MT1DP worsened Cd-induced nephrotoxicity, as evidenced in both Cd-poisoned individuals and in vitro cells. Moreover, MT1DP was found to reinforce Cd-induced toxicity in kidney cells by indirectly breaking the equilibrium between the pro-apoptotic and anti-apoptotic effects conducted by BAX and Bcl-xL, respectively. Collectively, our data unveiled that hepatocyte-derived MT1DP depends on the delivery of exosomes to wreak considerable havoc in Cd nephrotoxicity. This study offers new insights into the molecular mechanisms of Cd-induced kidney injury.

China and the UK use different risk-based approaches to derive soil screening or guideline values (SSVs; SGVs) for contaminants. Here we compare the approaches and the derived values for 6 illustrative contaminants. China’s SSVs are derived using an approach developed in the US as follows: for carcinogens, acceptable level of risk (ACR) is set at 10−6 and the SSVs calculated as 10−6 divided by the soil exposure and toxicity data; for non-carcinogens, the hazard quotient is 1 and the SSV is calculated as 1 divided by the soil exposure and toxicity data. The UK’s SGVs are calculated by the CLEA model, for which the Average Daily Exposure (ADE) from soil sources by a specific exposure route equals the health criteria values (HCVs) for that route, whether for carcinogens or a non-carcinogens. The UK’s CLEA model is also used here to derive SSVs with Chinese input parameters. China’s SSVs, the UK’s SGVs and values for Chinese conditions derived using the UK approach were as follows (mg/kg): As, <1, 35, 20; Cd, 20, 18, 11; Cr (VI), <1, 14, 29; benzene, 1, 1, 2; toluene, 1200, 3005, 3800; ethyl-benzene, 7, 930, 1200. By comparing the differences in toxicity assessment and risk characterization, exposure assessment and parameter types in the methodologies to obtain SSVs in China and the UK, and by combining the CLEA model with Chinese parameterisation, these comparisons highlight that the difference in toxicity assessment and risk characterization methods of carcinogens results in the biggest difference in SSVs between the 2 countries. However, for non-carcinogenic substances, the difference of SSVs calculation method and SSVs is small. The difference in SSVs for carcinogenic substances is also related to the route of exposure. For volatile organic compounds, the presence of indoor respiratory exposure pathways greatly reduces the differences caused by toxicity assessment and risk characterization methods. For non-volatile substances such as heavy metals, the effects of toxicity assessment and risk characterization methods are significant. The SSV of As obtained by the CLEA model with Chinese parameters is closer to the background value of soil in China. In the management of non-volatile contaminated sites such as heavy metals in China, the CLEA model can be used for risk assessment and calculation of site specific SSVs. In the future, China can use the UK method to strengthen its toxicity assessment and risk characterization methods for carcinogenic substances, to reduce the uncertainty in the risk assessment of contaminated sites and improve the scientific management of contaminated sites.

The microparticle content of 37 common facial and body scrubs commercially available in the United Arab Emirates was analyzed. The chemical composition, ash content, physical characteristics, loading, particle size and shape of the microparticles were determined. Only 11 out of 37 products were found to have microplastic content. Many of the remaining products exhibited microparticles composed of microcrystalline cellulose and crushed walnut shells. Differential scanning calorimetry showed that microplastic products had softening points as low as 84 °C. Plastic microbeads of 2 products were found to fuse at 100 °C. The fusion altered the flotation characteristics of the microbeads of one product. Heat treatment of the product at 100 °C in the presence of silica gel led to entrainment of the silica and partial fragmentation of the beads upon cooling. This may be understood as one mechanism of fragmentation of a microplastic with a low softening point in the presence of hard soil particles under temperature cycling.

Under the increasingly intensive measures for surface water restoration in China, point source discharge has been strictly regulated; however, for non-point sources, which constitute a large part of surface water pollutants, effective control has been difficult to reach. A comprehensive understanding of the characteristics of non-point source pollutants is essential for surface water improvement programs of cities such as Ningbo, on the southeast coast of China. Ningbo has made tremendous efforts in the past few years to control point source pollutants, but available data and management strategies on the non-point source pollutants are still limited. To this end, leachates of representative non-point source samples from the territory of Ningbo, including cropland and wetland soil, urban channel sediment, and poultry manure, were examined and compared focusing on the fluorescence characteristics and biodegradability of the dissolved organic matter (DOM). Results indicated that biodegradable dissolved organic carbon (BDOC) accounting for the total DOC was 46.7 ± 0.7% for cropland, wetland (56.3 ± 6.8%), non-sewage channel (60.1 ± 0.4%), sewage channel (74.5 ± 1.1%), and poultry manure (62.7 ± 4.5%). The leachates of the studied samples showed significant differences in both the amount and composition of DOM. However, a fluorescence component representing tryptophan-like substances identified by the excitation-emission matrix (EEM) combined with parallel factor (PARAFAC) analysis effectively predicted the BDOC variations among the studied samples. Moreover, under the studied nutrient concentrations, which were equivalent to Grade III water quality in China, nutrient limitation of microbial degradation was not observed. Threats to water quality, especially excessive consumption of dissolved oxygen, could be posed by the non-point source leachates due to their high bioavailability, large distribution, and weak nutrient restraint. Further investigations, including a quantitative evaluation of the non-point source pollution contribution, and pollutant blocking techniques are required.

Dichlorodiphenyltrichloroethane (DDT) is well known for its harmful effects and has been banned around the world. However, DDT is still frequently detected in natural environments, particularly in aquaculture and harbor sediments. In this study, 15 surface sediment samples were collected from a typical tropical bay (Zhanjiang Bay) in the South China Sea, and the levels of DDT and its metabolites in sediment and porewater samples were investigated. The results showed that concentrations of DDXs (i.e., DDT and its metabolites) in bulk sediments were 1.58–51.0 ng g⁻¹ (mean, 11.5 ng g⁻¹). DDTs (DDT and its primary metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE)) were the most prominent, accounting for 73.2%–98.3% (86.1% ± 12.8%) of the DDXs. Additionally, high-order metabolites (i.e., 1-chloro-2,2-bis(4′-chlorophenyl)ethylene (p,p′-DDMU), 2,2-bis(p-chlorophenyl)ethylene (p,p′-DDNU), 2,2-bis(p-chlorophenyl)ethanol (p,p′-DDOH), 2,2-bis(p-chlorophenyl)methane (p,p′-DDM), and 4,4′-dichlorobenzophenone (p,p′-DBP)) were also detected in most of the sediment and porewater samples, with DDMU and DBP being predominant. The DDTs concentration differed among the sampling sites, with relatively high DDTs concentrations in the samples from the aquaculture zone and an area near the shipping channel and the Haibin shipyard. The DDD/DDE ratios indicated a reductive dichlorination of DDT to DDD under anaerobic conditions at most of the sampling sites of Zhanjiang Bay. The possible DDT degradation pathway in the surface sediments of Zhanjiang Bay was p,p′-DDT/p,p′-DDD(p,p′-DDE)/p,p′-DDMU/p,p′-DDNU/ … /p,p′-DBP. The DDXs in the sediments of Zhanjiang Bay were mainly introduced via mixed sources of industrial DDT and dicofol, including fresh input and historical residue. The concentrations of DDXs in porewater samples varied from 66.3 to 250 ng L⁻¹, exhibiting a distribution similar to that in the accompanying sediments. However, the content of high-order metabolites was relatively lower in porewater than in sediment, indicating that high-order degradation mainly occurs in particles. Overall, this study helps in understanding the distribution, source, and degradation of DDT in a typical tropical bay.

The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS > MNPs/SS > EDB/SS > SS (95.86–99.72% > 93.10–98.5% > 89.66.98–98.40% > 74.90–90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water.

Heavy metal contaminants in Mirror Peninsula, East Antarctica, have rarely been studied and the source and influencing factors are poorly understood. We sampled a grid of 189 topsoil samples from Mirror Peninsula and analyzed the concentrations of Zn, Cu, U, Cr, Ga, Pb, Hg, Se and As; we also calculated the chemical index of alteration (CIA), a proxy of weathering. The results show that the distributions of Cr, Ga, Cu, and Zn are associated with weathering; the distributions of As and Pb are related to vehicle use and unloading activities at the wharfs, respectively; and the distribution of Hg is likely associated with both anthropogenic impacts and biological activity. The contamination level of these heavy metals in Mirror Peninsula is relatively low and within the controllable range. Both weathering processes and anthropogenic impacts can cause the enrichment of heavy metals; thus reliable source apportionment is crucial in studying heavy metal enrichment and contamination.

This study provided a comprehensive characterization on ingestion of different typologies of microplastics in several fish and invertebrate species from the Adriatic Sea, considered as a preferential area of plastic accumulation in the Mediterranean. Almost 500 organisms were sampled in the three sectors of Northern, Central and Southern Adriatic, testing the hypothesis that area of collection, habitat and feeding strategy might influence the occurrence of plastic particles in biota. In this study, the overall characterization considered separately plastic microparticles (MPs) from textile microfibers (MFs) which also included natural and semi-synthetic ones. Ingestion of MPs was a widespread phenomenon, but their number (typically 1 or 2) did not reveal any significant relationship with biometric values, geographical areas or ecological features of the species. Conversely, the frequency of ingestion, ranging from 13 to 35% of organisms containing MPs, appeared a more reliable index to highlight such differences, revealing higher values in species from Central and Southern basins compared to the Northern one, as well as in benthopelagic compared to benthic or pelagic organisms. Geographical differences also occurred in terms of size and typology of ingested particles, suggesting the importance of local river runoffs and surface currents dynamics. Textile microfibers (MFs) were also abundant in Adriatic food webs occurring in all the analyzed species with average numbers (3–10) and frequencies (40–70%) higher than those reported for MPs; further, an elevated percentage of MFs (>80%) was of natural or semi-synthetic origin.Overall, this study provided general insights toward the harmonization of a common biomonitoring strategy, as in the context of MSFD, including the suggestion of a frequency-based index and of a multi-species approach to increase the ecological relevance of assessment, as well as the comparability between different areas and trophic webs.

Bisphenol A (BPA), a monomer used for polycarbonate manufacture, has been widely reported as an endocrine-disrupting chemical (EDC). Among other alterations, BPA induces reproductive dysfunctionalities. Changes in the endocannabinoid system (ECS) have been recently shown to be associated with reproductive disorders. The ECS is a lipid-based signaling system (cannabinoid receptors, endocannabinoids and enzymatic machinery) involved in several physiological functions. The main goal of the present study was to assess the effects of two environmental concentrations of BPA (10 and 20 μg/L) on the ECS in 1-year old zebrafish gonads. In males, BPA increased the gonadosomatic index (GSI) and altered testicular levels of endocannabinoids as well as reduced the testicular area occupied by spermatogonia. In male liver, exposure to 20 μg/L BPA significantly increased vitellogenin (vtg) transcript levels. In female zebrafish, BPA altered ovarian endocannabinoid levels, elevated hepatic vtg mRNA levels as well as increased the percentage of vitellogenic oocytes in the ovaries. In conclusion, exposure to two environmentally relevant concentrations of BPA altered the ECS and consequently, gonadal function in both male and female zebrafish.