Probabilistic risk assessment of microplastics on aquatic biota in coastal sediments.

As an emerging form of pollution, microplastic contamination of the coastal ecosystems is one of the world's most pressing environmental concerns. Coastal sediments have been polluted to varying degrees by microplastics, and their ubiquitous presence in sediments poses a threat to marine organisms. However, there is currently no ecological risk assessment of microplastics on aquatic biota in sediments. This study, for the first time, established a new procedure to evaluate the toxicity of microplastics on aquatic biota in sediments, based on the probabilistic risk assessment (PRA) concept. The choice of Zhelin Bay as the case study site was based on its severe pollution status. The average content of microplastics in the sediments of Zhelin Bay was 2054.17 items kg-1 dry weight, and these microplastics consisted of 46 different species. Microplastics in sediments exist in five different forms, with the film form being the main composition, and the majority of microplastics have particle sizes ranging from 100 to 500 µm. Correlation analysis (CA) reveals significant negative correlations between microplastic abundance, and Al2O3 and SiO2. The toxicity of microplastics, based on the PRA concept, suggests that Zhelin Bay surface sediments had a low probability (3.43%) of toxic effects on aquatic biota.

Bioavailability and health risk assessment of Zn and Cd in edible tissues of two typical shellfish species using in vitro gastrointestinal digestion.

Dynamic extraction of edible tissues of Jinjiang oyster (Crassostrea rivularis) and Flower clam (Paphia undulata) was conducted using a fully biomimetic digestion (in vitro) method. The impact of different cooking methods on the bioavailability of Zn and Cd in the edible shellfish tissues was analyzed, and the human health risk of Zn and Cd was evaluated. The results show that the gastric biomimetic extractions of Zn and Cd in unheated samples of C. rivularis and P. undulata were higher than those in the intestinal biomimetic extraction. The extraction patterns of cooked samples were consistent with those of raw samples. The bioavailability of Zn and Cd in cooked samples of C. rivularis was 94.9% and 82.5%, respectively, indicating increased Zn bioavailability but decreased Cd bioavailability compared to the raw samples. The bioavailability of Zn and Cd in cooked samples of P. undulata was 85.1% and 83.0%, respectively, both of which decreased compared to the raw samples. Consumption of C. rivularis can provide 21.0% to 34.2% of the daily required Zn intake, while consumption of P. undulata can provide 3.8% to 6.4%. The intake of Cd from both shellfish species is below the monthly tolerable intake recommended by FAO/WHO. Consuming cooked C. rivularis can increase the intake of Zn and decrease the intake of Cd.

Bioenrichment preference and human risk assessment of arsenic and metals in wild marine organisms from Dapeng (Mirs) Bay, South China Sea.

Bioenrichment preference of arsenic and metals in wild marine organisms has been scarcely considered. Twenty species including fishes, cephalopods, crustaceans, and bivalve mollusks were collected from Dapeng (Mis) Bay and analyzed for arsenic and metals. Through this study, we had obtained the following four main conclusions: (1) average concentrations of arsenic and metals (µg/kg, wet weight) in the aquatic organism samples were 48.7 for Cr, 1762.0 for Mn, 20,632.8 for Fe, 33.0 for Co, 119.5 for Ni, 3184.7 for Cu, 12,040.5 for Zn, 389.0 for As, 189.1 for Se, 144.4 for Cd, 15.0 for Hg, and 55.3 for Pb; (2) factor analysis (FA) revealed that the studied twenty species exhibited three types of arsenic and metal bioenrichment preference;(3) non-carcinogenic health risk assessment indicated insignificant health effects from marine organism consumption; (4) carcinogenic health risk assessment revealed an unacceptable risk from consumption of nine species, seven of which were crustaceans.

Probabilistic ecotoxicological risk assessment of heavy metal and rare earth element mixtures in aquatic biota using the DGT technique in coastal sediments.

Heavy metals (HMs) are routine contaminants due to their extensive use worldwide. Rare earth elements (REEs) are emerging contaminants because of their global exploitation for use in the high-tech sector. Diffusive gradients in thin films (DGT) are an effective method for measuring the bioavailable component of pollutants. This study represents the first assessment of the mixture toxicity of HMs and REEs in aquatic biota using the DGT technique in sediments. Xincun Lagoon was chosen as the case study site because it has been contaminated by pollutants. Nonmetric multidimensional scaling (NMS) analysis reveals that a wide variety of pollutants (Cd, Pb, Ni, Cu, InHg, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb) are primarily impacted by sediment characteristics. Appraisal of single HM-REE toxicity reveals that the risk quotient (RQ) values for Y, Yb and Ce notably exceeded 1, demonstrating that the adverse effects of these single HMs and REEs should not be ignored. The combined toxicity of HM-REE mixtures in terms of probabilistic ecological risk assessment shows that the Xincun surface sediments had a medium probability (31.29%) of toxic effects on aquatic biota.

Nonmetric multidimensional scaling and probabilistic ecological risk assessment of trace metals in surface sediments of Daya Bay (China) using diffusive gradients in thin films.

This research is one main objective to assess combined toxicity of trace metal mixtures in aquatic biota in coastal sediments. Coastal sediments around the world are a major reservoir of trace metals from industrial wastewater discharge. Our case study site, Daya Bay in southern China, was selected because it has been under severe man-made impacts. Diffusive gradients in thin films (DGT) technique has proven to be a good method for measuring the bioavailability of trace metals. The bioavailability and distribution of trace metals in surface sediments were investigated along with their possible biological risks. The average bioavailable (DGT-labile) concentrations (µg/L) were 0.44 (V), 0.51 (Cr), 52.49 (Mn), 0.10 (Co), 1.36 (Ni), 0.74 (Cu), 14.53 (Zn), 0.97 (As), 0.14 (Se), 6.73 (Mo), 0.17 (Cd), 0.27 (Sb), 0.10 (W), and 1.32 (Pb). Nonmetric multidimensional scaling (NMS) is a robust multivariate ordination method that makes no assumptions about the distribution of the underlying data. NMS was used to explore that DGT-labile concentrations of trace metals were influenced by sediment properties. NMS results indicated that most DGT- labile trace metals influenced by sediment properties. Risk assessment of single trace metal toxicity revealed that risk quotient (RQ) values for Mn, Cu, Zn and Pb significantly exceeded 1, demonstrating that the toxic effects of these trace metals should be not ignored. The probabilistic ecological risk assessment for integral toxicity of one mixture of 14 trace metals revealed that Daya Bay surface sediments had a low probability (9.04 %) of adverse effects on aquatic biota.

Multi-index assessment of heavy metal contamination in surface sediments of the Pearl River estuary intertidal zone.

Surface sediments from 21 stations within the Pearl River estuary (PRE) intertidal zone were sampled for heavy metal contamination analysis. Average heavy metal concentrations (mg/kg) in the PRE intertidal zone were 118.5 (Cr), 860.4 (Mn), 19.5 (Co), 72.5 (Ni), 128.1 (Cu), 198.5 (Zn), and 73.0 (Pb), with the concentrations of Mn, Co, Ni, Cu, and Zn being significantly higher than their corresponding background values. The enrichment factor (EF) and geo-accumulation index (Igeo) reveal the same contamination status, with Pb, Ni, Co, Mn, and Cu showing slight to moderate contamination. Overall, the combined heavy metal concentration in the PRE intertidal surface sediments had a 24.7 % probability of toxic effects on aquatic biota based on the joint probabilistic risk (JPR) approach. Principal component analysis (PCA) coupled with the correlation analysis (CA) revealed that the heavy metal contamination in the PRE intertidal zone might originate from natural and anthropogenic sources.

Risk assessment of heavy metal and pesticide mixtures in aquatic biota using the DGT technique in sediments.

Heavy metals and pesticides (HMPs) are common contaminants due to their extensive use worldwide. Diffusive gradients in thin films (DGT) are a good method for measuring the bioavailable concentration of pollutants. This study represents the first evaluation of HMP toxicity in aquatic biota using the DGT technique in sediments. Zhelin Bay was selected as the case study site because it has been contaminated by pollutants. Nonmetric multidimensional scaling (NMS) analysis reveals that a diverse range of pollutants (V, Cr, Ni, Cu, Zn, As, Se, InHg, Mo, Cd, Sb, W, Pb, CLP, PYR) are mainly influenced by sediment characteristics. Assessment of single HMP toxicity found that the risk quotient (RQ) values for Mn, Cu, inorganic Hg (InHg), chlorpyrifos (CLP) and diuron (DIU) are significantly higher than 1, indicating that the adverse effects of these single HMPs should not be ignored. The combined toxicity of HMP mixtures based on probabilistic ecotoxicological risk assessment shows that Zhelin Bay surface sediments had a medium probability (54.6%) of toxic effects to aquatic biota.