Distribution, sources and ecological risks of organochlorine compounds (DDTs, HCHs and PCBs) in surface sediments from the Pearl River Estuary, China

Polychlorinated biphenyls (PCBs) and organochloride pesticides (OCPs) in sediment from the Beibu Gulf, China: Occurrence, spatial-temporal distribution, source, historical variation and ecological risks

This study comprehensively analyzed 11 polychlorinated biphenyls (PCBs) and 16 organochlorine pesticides (OCPs) in 87 surface sediment samples collected across two seasons and in a sediment core from the Beibu Gulf, China. Overall, only a limited number and low concentrations of PCBs and OCPs were detected. In surface sediments, ΣPCBs concentrations were higher in summer (mean: 0.27 ± 0.37 ng/g dw) compared to winter (mean: 0.07 ± 0.06 ng/g dw), while ΣOCPs showed no significant seasonal variation (summer, mean: 0.19 ± 0.19 ng/g dw; winter, mean: 0.17 ± 0.07 ng/g dw). 4,4'-trichlorobiphenyl (PCB 28), 2,3,5,6-Tetrachlorobiphenyl (PCB 65) and p,p'-Dichlorodiphenyldichloroethylene (p,p'-DDE) were the most predominant contaminants, with average concentrations accounting for >90 % of the ΣPCBs and ΣOCPs, respectively. Spatial distribution revealed higher ΣPCBs concentrations in the southern Beibu Gulf compared to other areas. Industrial productions, shipping activities, as well as ocean current transport appear to be key sources of PCBs in studied region, while the aerobic degradation of residual DDT likely explains the widespread presence of DDE. In sediment core, both ΣPCBs and ΣOCPs exhibited parabolic variation trends along the sediment core depth, reflecting historical use in the Beibu Gulf, with recent declines in new inputs. Risk assessments indicated that PCBs and OCPs in Beibu Gulf sediments pose minimal ecological risks. These findings offer valuable scientific insights to support future research on typical organic pollutants in the Beibu Gulf.

Sediment-water exchange and risk assessment of pesticidal persistent organic pollutants in Bharathappuzha and Periyar Riverine region along the Arabian Sea

Considering the extensive agricultural practices along the perennial rivers, viz. Periyar and Bharathappuzha of Kerala in the southwest coast of India, the first comprehensive surveillance of new and legacy organochlorine pesticides (OCPs) in surface sediment was conducted. Further, the sediment-water exchange fluxes have been elucidated. Mean concentrations of total HCH, DDT and endosulfan were 0.84 ng/g, 0.42 ng/g and 0.30 ng/g for Bharathappuzha Riverine sediment (BRS) and 1.08 ng/g, 0.39 ng/g and 0.35 ng/g for Periyar Riverine sediment (PRS). The dominance α-HCH and β-HCH isomers in PRS and BRS reflect the ongoing use of technical HCH in Kerala. The calculated KSW in both rivers was very low in comparison with other Indian rivers. The average log K'OC for all the detected OCPs in both the rivers was lower than the predicted log KOC in equilibrium indicating the higher adherence of OCPs to sediment. Furthermore, fugacity fraction (fs/fw) was < 1.0 for all OCPs confirming the net deposition of OCPs into the sediment. Sediment concentrations for each of the OCPs in PRS and BRS did not surpass the threshold effect level and probable effect level as stipulated by the Canadian Council of Ministry of the Environment Guidelines. In addition, all the sites of both rivers had sediment quality guideline quotient (SQGQ) values below 0.1 indicating the absence of significant biological and ecological risks.

New insight into the bioaccumulation and trophic transfer of free and conjugated antibiotics in an estuarine food web based on multimedia fate and model simulation

The substantial utilization of antibiotics causes their "pseudo-persistence" in offshore environments. Published studies on antibiotic surveillance in food webs have primarily emphasized on parent forms; however, the compositions and concentrations of conjugated antibiotics in aquatic organisms remain largely unexplored. This study systematically examined the distribution characteristics and trophodynamics of free antibiotics and their conjugated forms in an estuarine food web. Total antibiotic levels differed insignificantly between the surface and bottom waters. The total mean values of free antibiotics in crabs, fish, shrimps, sea cucumbers, and snails varied from 0.77 to 1.4 ng/g (wet weight). The numbers and values of antibiotics rose in these biological samples after enzymatic hydrolysis. Conjugated antibiotics accounted for 23.8-76.9% of the total antibiotics in the biological samples, revealing that conjugated forms play a non-negligible role in aquatic organisms. More number of antibiotics exhibited bioaccumulation capabilities after enzymatic hydrolysis. In the food web, the free forms of anhydroerythromycin and conjugated forms of trimethoprim and ciprofloxacin underwent trophic dilution, whereas the free forms of trimethoprim and conjugated forms of ofloxacin underwent trophic amplification. The present work provides new insights into the bioaccumulation and trophic transfer of free and conjugated antibiotics in food webs.

Occurrence, distribution, and ecological risks of polyhalogenated carbazoles in sediments from Daya Bay and Pearl River Estuary, China

Polyhalogenated carbazoles (PHCZs) are a group of emerging organic pollutants attracting increasing concern. In this study, 32 sediment samples were collected from the Pearl River Estuary (PRE) and adjacent Daya Bay (DYB) in China and were investigated for the occurrence and distribution of PHCZs. Total concentration of sedimentary PHCZs (∑PHCZs) ranged from 0.79 to 3.08 ng/g in PRE and 0.89 to 1.95 ng/g in DYB, both containing 3,6-dichlorocarbazole as the main component. Higher concentrations of ∑PHCZs were found in the rivers-mouth and inner part of the PRE indicating their main origins from anthropogenic activities. Notably, concentrations of brominated carbazoles (BCZs) gradually increased offshore, which suggests the potential bio-transformation of BCZs under a saline environment. The toxic equivalent of PHCZs was estimated at 0.13-0.34 pg TEQ/g suggesting limited dioxin-like effects on local organisms.

Ecological Risk Assessment of Organochlorine Pesticides and Polychlorinated Biphenyls in Coastal Sediments in China

Although the ecological risk of emerging contaminants is currently a research hotspot in China and abroad, few studies have investigated the ecological risk of pesticide pollutants in Chinese coastal sediments. In this study, nine pesticide pollutants included in the "List of New Key Pollutants for Control (2023 Edition)" issued by the Chinese government were used as the research objects, and the environmental exposure of pesticide pollutants in China's coastal sediments was analyzed. The baseline sediment quality criteria were deduced using the balanced distribution method, and a multi-level ecological risk assessment of pesticides in sediment was performed. The results showed that the nine pesticide pollutants were widespread in Chinese coastal sediments, with concentrations ranging from 0.01 ng·g-1 to 330 ng·g-1. The risk quotient assessment showed that endosulfan and DDT posed medium environmental risks to the Chinese coastal sediment environment, and PCBs posed medium risks in some bays of the East China Sea. The semi-probabilistic, optimized semi-probability evaluation and joint probability curve (JPC) assessments all show that endosulfan and DDT pose a certain degree of risk to the environment.

Postnatal Exposure to the Endocrine Disruptor Dichlorodiphenyltrichloroethane Affects Adrenomedullary Chromaffin Cell Physiology and Alters the Balance of Mechanisms Underlying Cell Renewal

Dichlorodiphenyltrichloroethane (DDT) is a wide-spread systemic pollutant with endocrine disrupting properties. Prenatal exposure to low doses of DDT has been shown to affect adrenal medulla growth and function. The role of postnatal exposure to DDT in developmental disorders remains unclear. The aim of the present investigation is to assess growth parameters and the expression of factors mediating the function and renewal of chromaffin cells in the adult adrenal medulla of male Wistar rats exposed to the endocrine disruptor o,p'-DDT since birth until sexual maturation. The DDT-exposed rats exhibited normal growth of the adrenal medulla but significantly decreased tyrosine hydroxylase production by chromaffin cells during postnatal period. Unlike the control, the exposed rats showed enhanced proliferation and reduced expression of nuclear β-catenin, transcription factor Oct4, and ligand of Sonic hedgehog after termination of the adrenal growth period. No expression of pluripotency marker Sox2 and absence of Ascl 1-positive progenitors were found in the adrenal medulla during postnatal ontogeny of the exposed and the control rats. The present findings indicate that an increase in proliferative activity and inhibition of the formation of reserve for chromaffin cell renewal, two main mechanisms for cell maintenance in adrenal medulla, in the adult DDT-exposed rats may reflect a compensatory reaction aimed at the restoration of catecholamine production levels. The increased proliferation of chromaffin cells in adults suggests excessive growth of the adrenal medulla. Thus, postnatal exposure to DDT alters cell physiology and increases the risk of functional insufficiency and hyperplasia of the adrenal medulla.

Alternatives Exert Higher Health Risks than Bisphenol A on Indo-Pacific Humpback Dolphins

The detrimental effects of bisphenol (BP) exposure are a concern for vulnerable species, Indo-Pacific humpback dolphins (Sousa chinensis). To investigate the characteristics of BP profiles and their adverse impact on humpback dolphins, we assessed the concentrations of six BPs, including bisphenol A (BPA), bisphenol S (BPS), bisphenol F (BPF), bisphenol AF (BPAF), bisphenol B (BPB), and bisphenol P (BPP) in blubber (n = 26) and kidney (n = 12) of humpback dolphins stranded in the Pearl River Estuary, China. BPS accounted for the largest proportion of the total bisphenols (∑BPs) in blubber (55%) and kidney (69%). The concentration of ∑BP in blubber was significantly higher than that in the kidney and liver. The EC50 values of five BPA alternatives were lower than those of BPA in humpback dolphin skin fibroblasts (ScSF) and human skin fibroblasts (HSF). ScSF was more sensitive to BPS, BPAF, BPB, and BPP than HSF. The enrichment pathway of BPA was found to be associated with inflammation and immune dysregulation, while BPP and BPS demonstrated a preference for genotoxicity. BPA, BPP, and BPS, which had risk quotients (RQs) > 1, were found to contribute to subhealth and chronic disease in humpback dolphins. According to the EC50-based risk assessment, BPS poses a higher health risk than BPA for humpback dolphins. This study successfully evaluated the risks of bisphenols in rare and endangered cetacean cell lines using a noninvasive method. More in vivo and in field observations are necessary to know whether the BPA alternatives are likely to be regrettable substitutions.

Distribution, Transfer, and Health Risk of Organochlorine Pesticides in Soil and Water of the Huangshui River Basin

The potential negative impacts of organochlorine pesticides on the environment and human health continue to receive attention. In order to study the spatial distribution characteristics of organochlorine pesticides in the inland alpine region, researchers collected soil and water samples in the Huangshui River Basin of the Qinghai-Tibetan Plateau and tested them for organochlorine pesticide residues represented by dichlorodiphenyltrichloroethane (DDT) and hexachlorohexane (HCH). The study identified the sources of OCPs by component analysis. We also constructed the LEVEL III model, applicable to the Huangshui River Basin, and used it to study the migration patterns of OCPs in various environmental media. OCPs were detected at low levels in the study area environment. The results of the OCPs source analysis show that there are both historical residuals and new sources in the region. Residual DDTs may originate from the mixture of technical DDTs and dicofol, and HCHs may originate from lindane or technical HCH. DDTs are mainly stored in soil, the input and output pathways are mainly atmospheric advection input and output, and its transport behavior in the environment is mainly air-soil exchange. Carcinogens in the study area pose little threat to people exposed to contaminated soil and contaminated water, but the cancer risk to children is greater than to adults. This study is helpful to managers of regional pesticide management and control.

Organochlorine contaminants in sediments and factors influencing their distribution in the natural marine protected area in the gulf of Mexico

The aim of this study was to determine the concentration of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in marine sediments of a natural marine protected area (NMPA), Veracruz Reef System (VRS), in the Gulf of Mexico (GoM). This NMPA represents one of the first coastal sites with port activity in Mexico, which causes a range of human activities that require adequate planning so as not to impact and destroy this marine protected area; In this sense, this work represents the first effort aimed at diagnosing the presence of organochlorine contaminants in reef sediments from the mainland, both from the adjacent port area and from more distant regions with dominant agricultural activities that ultimately affect this NMPA. Content of organic matter (OM), carbonates and grain-size composition were determined to investigate their influence on compounds distribution in the sediment through multivariate analysis. The potential risk represented by organochlorines concentrations was evaluated taking as reference Sediment Quality Guidelines (SQGs). Levels of ∑PCBs, ∑DDTs, ∑HCHs and ∑Cyclodienes ranged from 11.59 to 29.79, < 0.01 to 34.11, 22.10 to 102.80, and 17.21-104.45 ng g-1 dry weight (DW), respectively. The statistical analysis revealed that the content of mud and organic matter were the parameters that might influence PCBs distribution in the sediment while OCPs could be influenced by sand and carbonate. The theoretical risk assessment estimated with the results obtained showed that concentrations of lindane, endrin, dieldrin and p,p'-DDT could have an adverse effect on the reef benthic community and continued monitoring is required. The data obtained on the organochlorine contaminants (OCs) considered in this work will contribute to support the strategies proposed by the Mexican federal government entity to continue with the conservation and surveillance of this NMPA and thereby guarantee the least impact derived mainly from port and related agricultural activities.

Distribution, sources, and ecological risk assessment of polychlorinated biphenyls (PCBs) in the estuary of Dagu River, China

Four different types of 0-30 cm soil/sediment samples were collected from aquaculture land, farmland, industrial land and river bottom sediment in the estuary area of Dagu River, and the pollution status and sources of 7 PCB congeners were analyzed. The results showed that the mean values of Σ7PCBs in soil/sediments of different land use types were 5.01 ng g-1 dw for industrial land, 3.6 ng g-1 dw for estuarine sediments, 2.09 ng g-1 dw for farmland soil and 1.78 ng g-1 dw for farming land. All samples were at low pollution levels and pose little ecological risks. PCBs in the samples are mainly comprised of highly chlorinated biphenyls, and their content decreases gradually with increasing sampling depth. Based on the principal component analysis, it is concluded that the main source of PCBs in the study area is shipping activities, in addition to atmospheric transport and sedimentation sources.

Higher ecological risks and lower bioremediation potentials identified for emerging OPEs than legacy PCBs in the Beibu Gulf, China

The production and use of organophosphate esters (OPEs) as substitutes for traditional halogenated flame retardants is increasing, resulting in greater global concern related to their ecological risks to marine environments. In this study, polychlorinated biphenyls (PCBs) and OPEs, representing traditional halogenated and emerging flame retardants, respectively, were studied in multiple environmental matrices in the Beibu Gulf, a typical semi-closed bay in the South China Sea. We investigated the differences in PCB and OPE distributions, sources, risks, and bioremediation potentials. Overall, the concentrations of emerging OPEs were much higher than those of PCBs in both seawater and sediment samples. Sediment samples from the inner bay and bay mouth areas (L sites) accumulated more PCBs, with penta- and hexa-CBs as major homologs. Chlorinated OPEs were prevalent in both seawater and sediment samples from the L sites, whereas tri-phenyl phosphate (TPHP) and tri-n-butyl phosphate (TNBP) were predominant at the outer bay (B sites) sediment samples. Source identification via principal component analysis, land use regression statistics, and δ13C analysis indicate that PCBs were mainly sourced from the atmospheric deposition of sugarcane and waste incineration, whereas sewage inputs, aquaculture, and shipping activity were identified as sources of OPE pollution in the Beibu Gulf. A half-year sediment anaerobic culturing experiment was performed for PCBs and OPEs, and the results only exhibited satisfactory dechlorination for PCBs. However, compared with the low ecological risks of PCBs to marine organisms, OPEs (particularly trichloroethyl phosphate (TCEP) and TPHP) exhibited low to medium threats to algae and crustaceans at most sites. Given their increasing usage, high ecological risks, and low bioremediation potential in enrichment cultures, pollution by emerging OPEs warrants close attention.

Characterization of metal resistance genes carried by waterborne free-living and particle-attached bacteria in the Pearl River Estuary

Toxic metals can substantially change the bacterial community and functions thereof in aquatic environments. Herein, metal resistance genes (MRGs) are the core genetic foundation for microbial responses to the threats of toxic metals. In this study, waterborne bacteria collected from the Pearl River Estuary (PRE) were separated into the free-living bacteria (FLB) and particle-attached bacteria (PAB), and analyzed using metagenomic approaches. MRGs were ubiquitous in the PRE water and mainly related to Cu, Cr, Zn, Cd and Hg. The levels of PAB MRGs in the PRE water ranged from 8.11 × 10⁹ to 9.93 × 10¹² copies/kg, which were significantly higher than those of the FLB (p < 0.01). It could be attributed to a large bacterial population attached on the suspended particulate matters (SPMs), which was evidenced by a significant correlation between the PAB MRGs and 16S rRNA gene levels in the PRE water (p < 0.05). Moreover, the total levels of PAB MRGs were also significantly correlated with those of FLB MRGs in the PRE water. The spatial pattern of MRGs of both FLB and PAB exhibited a declining trend from the low reaches of the PR to the PRE and on to the coastal areas, which was closely related to metal pollution degree. MRGs likely carried by plasmids were also enriched on the SPMs with a range from to 3.85 × 10⁸ to 3.08 × 10¹² copies/kg. MRG profiles and taxonomic composition of the predicted MRG hosts were significantly different between the FLB and PAB in the PRE water. Our results suggested that FLB and PAB could behave differential response to heavy metals in the aquatic environments from the perspective of MRGs.

Status of different anthropogenic organic pollutants accumulated in sediments from Olt River Basin, Romania: From distribution and sources to risk assessment

Some organic pollutants including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) have been banned from production worldwide, but due to their toxicity and persistence are still of concern. Also, unintentional by-products of combustion and industrial processes such as polycyclic aromatic hydrocarbons (PAHs), represent a permanent threat to the safety of the environment and the population. In this study, surface sediment samples from the middle and lower Olt River Basin (ORB), Romania, including dams, the main tributaries and the confluence with Danube River were collected during seasonal sampling campaigns in 2019 and analyzed for 13 OCPs, 12 PCBs and 15 PAHs in order to evaluate the impact of the main anthropogenic activities in the area (industrial activities and agriculture) and the ecological status of the ORB. The registered levels of OCPs, PCBs and PAHs in surface sediments varied from low to significantly polluted environments, indicating a clear spatial distribution between sites based on concentrations and congener profiles correlated with the influence of anthropogenic activities in the surrounding area. Based on some molecular diagnostic ratio and multivariate statistical analysis, both non-point sources and point sources deposition by surface runoff or atmospheric deposition were identified. Overall, the contamination profile of the study area reveals significant amounts of organochlorine compounds, resulting from the industrial production of chlorinated products, including lindane, but also from the long-term agricultural use of both HCHs and DDTs, more than half of the sites having levels that pose a potential risk for benthic organisms. Therefore, levels of POPs in the hot-spots sampling locations raise numerous concerns about the safety of the environment and the population in the region, requiring immediate actions.

Spatiotemporal trends of ultraviolet absorbents in oysters from the Pearl River Estuary, south China during 2015-2020

Ultraviolet absorbents (UVAs) are widely used in various industrial materials, pharmaceuticals, and personal care products, resulting in their frequent occurrences in sediment, water, and biota. However, our understanding of the spatiotemporal characteristics and long-term contamination status of UVAs is still limited. Here, a 6-year biomonitoring study with oysters during wet and dry seasons was conducted to examine the annual, seasonal, and spatial characteristics of UVAs in the Pearl River Estuary (PRE), China. The concentrations of Σ₆UVA ranged from 9.1 to 119 (geometric mean ± standard deviation: 31 ± 22) ng/g dry wt. and peaked in 2018. Significant spatiotemporal variations in UVA contamination were observed. The concentrations of UVAs in oysters during the wet season were higher than the dry season, and concentrations in the more industrialized eastern coast were higher than the western coast (p < 0.05). Environmental factors, including precipitation, temperature, and salinity in water significantly impacted the UVA bioaccumulation in the oysters. The present study highlights that long-term biomonitoring with oysters provided valuable insight in the magnitude and seasonal variation of UVAs in this highly dynamic estuary.

Novosphingobium album sp. nov., Novosphingobium organovorum sp. nov. and Novosphingobium mangrovi sp. nov. with the organophosphorus pesticides degrading ability isolated from mangrove sediments

Members of the genus Novosphingobium were frequently isolated from polluted environments and possess great bioremediation potential. Here, three species, designated B2637^T, B2580^T and B1949^T, were isolated from mangrove sediments and might represent novel species in the genus Novosphingobium based on a polyphasic taxonomy study. Phylogenomic analysis revealed that strains B2580^T, B1949^T and B2637^T clustered with Novosphingobium naphthalenivorans NBRC 102051^T, 'N. profundi' F72 and N. decolorationis 502str22^T, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between isolates and their closely related species were less than 94 and 54 %, respectively, all below the threshold of species discrimination. The sizes of the genomes of isolates B2580^T, B2637^T and B1949^T ranged from 4.4 to 4.6 Mb, containing 63.3-66.4 % G+C content. Analysis of their genomic sequences identified genes related to pesticide degradation, heavy-metal resistance, nitrogen fixation, antibiotic resistance and sulphur metabolism, revealing the biotechnology potential of these isolates. Except for B2637^T, B1949^T and B2580^T were able to grow in the presence of quinalphos. Results from these polyphasic taxonomic analyses support the affiliation of these strains to three novel species within the genus Novosphingobium, for which we propose the name Novosphingobium album sp. nov. B2580^T (=KCTC 72967^T=MCCC 1K04555^T), Novosphingobium organovorum sp. nov. B1949^T (=KCTC 92158^T=MCCC 1K03763^T) and Novosphingobium mangrovi sp. nov. B2637^T (KCTC 72969^T=MCCC 1K04460^T).

Occurrence of OCPs & PCBs and their effects on multitrophic biological communities in riparian groundwater of the Beiluo River, China

Persistent Organic Pollutants (POPs) may exert adverse effects on human and ecosystem health. However, as an ecologically fragile zone with strong interaction between river and groundwater, the POPs pollution in the riparian zone has received little attention. The goal of this research is to examine the concentrations, spatial distribution, potential ecological risks, and biological effects of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the riparian groundwater of the Beiluo River, China. The results showed that the pollution level and ecological risk of OCPs in riparian groundwater of the Beiluo River were higher than PCBs. The presence of PCBs (Penta-CBs, Hexa-CBs) and CHLs, respectively, may have reduced the richness of bacteria (Firmicutes) and fungi (Ascomycota). Furthermore, the richness and Shannon's diversity index of algae (Chrysophyceae and Bacillariophyta) decreased, which could be linked to the presence of OCPs (DDTs, CHLs, DRINs), and PCBs (Penta-CBs, Hepta-CBs), while for metazoans (Arthropoda) the tendency was reversed, presumably as a result of SULPHs pollution. In the network analysis, core species belonging to bacteria (Proteobacteria), fungi (Ascomycota), and algae (Bacillariophyta) played essential roles in maintaining community function. Burkholderiaceae and Bradyrhizobium can be considered biological indicators of PCBs pollution in the Beiluo River. Note that the core species of interaction network, playing a fundamental role in community interactions, are strongly affected by POPs pollutants. This work provides insights into the functions of multitrophic biological communities in maintaining the stability of riparian ecosystems through the response of core species to riparian groundwater POPs contamination.

Potential risk of co-occurrence of microplastics and chlorinated persistent organic pollutants to coastal wetlands: Evidence from a case study

Microplastic (MP) pollution in coastal wetlands is of a global concern. Little attention has been paid to the co-occurrence and corresponding risk of MPs with pollutants, especially refractory chlorinated persistent organic pollutants (CPOPs). A case study of Zhejiang, China was conducted to investigate the occurrence of MPs and targeted CPOPs in coastal wetlands. MPs were 100% detected, but with the lowest abundance in coastal wetlands (average: 666.1 ± 159.1 items kg^-1), as compared to other 6 terrestrial ecosystems (average: 1293.9 ± 163.7 items kg^-1) including paddy field, upland, facility vegetable field, forestland, urban soil, and grassland. A total of 35 kinds CPOPs were also detected in all studied coastal wetlands, with their concentration almost under 10 μg kg^-1 (90.1%). Both enrichment of MPs and CPOPs was affected by sediment TOC, wetland vegetation and land use simultaneously. Interestingly, the occurrence of MPs was significantly correlated with polychlorinated biphenyls (PCBs) but not organochlorine pesticides (OCPs). Results of co-occurrence pollution assessment of MPs and CPOPs further indicated only Hangzhou Bay showed the ecological risk among all tested wetlands. This would suggest a potential risk of co-occurrence of MPs and modern CPOPs in coastal wetland in economic development area. Possible reason may lie on strong MP vector effect to CPOPs. More attention should thus be paid to other wetlands polluted by MPs and MP-carrying CPOPs in area with relatively great environmental pressure induced by human activity. This study may provide reference for a better understanding with respect to the risk level posed by co-occurrence of MPs and CPOPs to global coastal wetlands.

Quantification of insecticides in commercial seafood sold in East Asian markets: risk assessment for consumers

The extraction of 21 insecticides and 5 metabolites was performed using an optimized and validated QuEChERS protocol that was further used for the quantification (GC-MS/MS) in several seafood matrices (crustaceans, bivalves, and fish-mudskippers). Seven species, acquired from Hong Kong and Macao wet markets (a region so far poorly monitored), were selected based on their commercial importance in the Indo-Pacific region, market abundance, and affordable price. Among them, mussels from Hong Kong, together with mudskippers from Macao, presented the highest insecticide concentrations (median values of 30.33 and 23.90 ng/g WW, respectively). Residual levels of fenobucarb, DDTs, HCHs, and heptachlors were above the established threshold (10 ng/g WW) for human consumption according to the European and Chinese legislations: for example, in fish-mudskippers, DDTs, fenobucarb, and heptachlors (5-, 20- and tenfold, respectively), and in bivalves, HCHs (fourfold) had higher levels than the threshold. Risk assessment revealed potential human health effects (e.g., neurotoxicity), especially through fish and bivalve consumption (non-carcinogenic risk; ΣHQ_LT > 1), and a potential concern of lifetime cancer risk development through the consumption of fish, bivalves, and crustaceans collected from these markets (carcinogenic risk; ΣTCR > 10^-4). Since these results indicate polluted regions, where the seafood is collected/produced, a strict monitoring framework should be implemented in those areas to improve food quality and safety of seafood products.

Distribution, Sources and Risk Assessment of Polychlorinated Biphenyls in Sediments from Beiluo River

The distribution and source of polychlorinated biphenyls (PCBs) pollution in the Beiluo River, the secondary tributary of the Yellow River, still remain unclear. With the purpose of determining the distribution, origins, and pollution levels of PCBs and their consequences on ecological risks, the concentrations of 27 PCBs at 17 locations in the sediments of the Beiluo River were examined in this study. The results showed that the mass concentrations of ∑PCBs in the sediment ranged from 0.12 to 1.25 ng∙g^-1 (DW), with the highest point at sampling site B13 downstream of the river. Compared to most river sediments, both domestically and internationally, the concentration of PCBs in the sediment of the Beiluo River was at a low level, with 10-PCB and 6-PCB as the main components, indicating that the PCBs that are difficult to volatilise and degrade are more likely to remain in the sediment. The origins of PCBs in the sediments of the Beiluo River were examined by using positive matrix factorisation (PMF). The results revealed that the contamination of PCBs in the sediments of the Beiluo River mainly resulted from industrial emissions, technical PCB mixtures, and coal and wood combustion. The results of the ecological risk assessment indicated that PCBs in the sediments of the study area rarely contribute to adverse biological effects and the potential low risk to the environment.

Past, present and future trends of selected pesticidal and industrial POPs in Kuwait

Given the background of current global initiatives for controlling persistent organic pollutants (POPs), an overview of the scientific knowledge about the POPs issues in Kuwait is presented in this study. Both acute and chronic exposure to POPs can be associated with a wide range of deleterious health effects, including illness and death. POPs have drawn significant political and scientific interest in their fate and actions, particularly where local releases have resulted in dispersed contamination far from the source regions. These concerns inevitably led to the establishment of the Stockholm Convention (SC) on POPs. In recent years, Kuwait has carried out a wide variety of environmental research, in particular, on the monitoring of POPs in different matrices. The technological development facilitated to achieve the opposite monitoring of pesticidal and industrial POPs. The majority of these POPs are from a point source. Kuwait does not have pesticide manufacturing facilities and has not produced pesticides for POPs in the past. In the agriculture sector, Kuwait primarily imports pesticides for pest and disease control. This review encompasses the historical presence and current status of (pesticidal) organochlorine pesticides (OCPs) and (industrial POPs) PCBs and PBDEs in Kuwait based on the export, import, consumption and usage. This research also contrasts pesticide and industrial POP data from various Kuwaiti environmental matrices with data from other parts of Asia, the EU, the USA and Africa.

Widespread occurrence of emerging E-waste contaminants - Liquid crystal monomers in sediments of the Pearl River Estuary, China

Liquid crystal monomers (LCMs), commonly used in screens of electronic devices, have recently been identified as a group of emerging chemicals of concern associated with e-waste. They are potentially persistent, bioaccumulative, and toxic substances, and may pose a threat to the marine ecosystem. The Pearl River Estuary (PRE) receives organic contaminants discharged from the Pearl River Delta region, where primitive handling of e-waste is widespread. However, information on the pollution status of LCMs in the PRE is absent. Herein, a rapid and robust analytical method was established using ultrasonic extraction, solid phase extraction cleanup, and GC-Orbitrap-MS analysis. The spatial distribution of 39 target LCMs was investigated in 45 surface sediment samples from the PRE. Ten LCMs were detected, with ΣLCMs ranged from 0.9 to 31.1 ng/g dry weight. Our results demonstrated a widespread occurrence of LCMs in the sediments of the PRE, and a gradient of their contamination from inshore to offshore regions, indicating land-based origins. Our reported ΣLCMs concentrations were relatively higher compared to many other legacy and emerging pollutants found in the same investigated area. Preliminary risk assessment showed 3VbcH, Pe3bcH and tFMeO-3bcHP might be the top 3 risk contributors in the PRE. Further investigation on the ecological impact of LCMs on marine benthic ecosystems, as well as identification of their sources and control measures are warranted.

Organochlorine pesticides in marine sediments and seawater from Cirebon coastal water, West Java, Indonesia: Concentration, spatial distribution, potential sources, and ecological risk assessment

Organochlorine pesticides (OCPs) were investigated in surface sediments and seawater from three major estuaries at Cirebon coastal water, West Java Province, Indonesia. Total concentrations of OCPs in seawater and sediment varied from 10 to 120 ng/L (32 ± 36 ng/L) and 1.5 to 17 ng/g dw (mean of 7.4 ± 4.0 ng/g dw), respectively. OCPs concentrations in Sukalila estuary were higher than those detected in Bondet and Kejawan estuaries. The drins group was the predominant OCPs contaminant in seawater and sediment samples. Historical application of DDT, recent use of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), and application of technical hexachlorocyclohexanes (HCHs) are significant sources of DDTs and HCHs, respectively. The concentrations of γ-HCH and heptachlor epoxide in marine sediment elevated the value of Threshold Effect Limit (TEL) in 48% of the total study stations but lowered the value of Probable Effect Limit (PEL), suggesting that they ocassionally trigger adverse effects on benthic organisms.

Occurrence, origin and potential ecological risk of dissolved polycyclic aromatic hydrocarbons and organochlorines in surface waters of the Gulf of Gabès (Tunisia, Southern Mediterranean Sea)

We investigated the occurrence, origin, and potential ecological risk of dissolved polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCBs) and organochlorine pesticides (OCPs) in 27 surface water samples collected from a highly anthropized and industrialized area in the Gulf of Gabès (Tunisia, Southern Mediterranean Sea) in October-November 2017. The results demonstrated a wide range of concentrations (ng L^-1) with the following decreasing order: Ʃ16 PAHs (17.6-71.2) > Ʃ20 PCBs (2.9-33.7) > Ʃ6 DDTs (1.1-12.1) > Ʃ4 HCHs (1.1-14.8). Selected diagnostic ratios indicated a mixture of both pyrolytic and petrogenic sources of PAHs, with a predominance of petrogenic sources. PCB compositions showed distinct contamination signatures for tetra- to hepta-chlorinated PCBs, characteristic of contamination by commercial (Aroclor) PCB mixtures. The dominant OCP congeners were γ-HCH, 2,4'-DDD and 2,4'-DDE, reflecting past use of Lindane and DDTs in the study area. Agricultural, industrial and domestic activities, as well as atmospheric transport are identified as potential sources of PAHs, PCBs and OCPs in surface waters of the Gulf of Gabès. Toxic equivalents (TEQs) suggested a low carcinogenic potential for PAHs in seawater samples (mean of 0.14 ng TEQ L^-1). Evaluation of risk coefficients revealed low risk for PAHs and PCBs, and moderate to severe risk for OCPs.

Identification of toxicity factors and causal analysis of toxicity in surface sediments from Liaohe river basin, Northeast China using an effect guidance strategy

Sediments play a pivotal role in maintaining the aquatic ecological status of rivers. However, the determination of the key toxicants that consider the combined effects of all sediment-related contaminants are still challenging and necessary for an appropriate sediment risk assessment. The effects of sediments on aquatic organisms have been reported in Liaohe River, but their key toxicity factors are not well known. To determine the key toxicity factors, twenty-six surface sediment samples from Liaohe River tributaries in Northeast China were collected. Acute toxicity test of midge larvae results showed that 6 of 26 tributaries had obvious toxic effects, with survival rates of 37%-57% (p < 0.05). The masking test showed that the main pollutants in the surface sediments of T7 and T16 were metals, that of T8 was an organic pollutant, those of T19 and T26 were organic pollutants and ammonia, and those of T17 were heavy metal and ammonia. Chemical analysis showed that the relatively high concentrations of ammonia were only presented in surface sediments of T17, T19, and T26, with PTU of 1.5, 1.2 and 1.1, respectively, whereas heavy metals were markedly high in surface sediments from T7 and T16, with PTU of 0.92 and 0.61, respectively. Interestingly, the observed toxicity in surface sediments agreed with the toxicity predicted by chemical analysis Moreover, the significant correlation between the survival and volume ratio of the sediment and overlying water confirmed ammonia nitrogen was key toxicity factor in T17, T19, and T26, whereas Cu was the key toxicity factor in T7 that cause the biological toxicity. In conclusion, the major toxic factors of ammonia and copper in the sediments were identified. Moreover, our study suggested that effect guidance strategy was an effective method for sediment quality assessment.

Historic changes of polychlorinated biphenyls (PCBs) in juvenile and adult cetaceans from the Pearl River estuary from 2003 to 2020

Polychlorinated biphenyls (PCBs), as a type of legacy persistent organic pollutants, pose significant health threats to wildlife. However, long-term residue changes and profiles of PCBs in cetaceans have not been extensively studied in the Pearl River Estuary (PRE), an important marine mammal area in China. Here, the body burdens, spatiotemporal trends, and health risks of 21 chlorobiphenyl congeners (∑21CBs) were analyzed in blubber samples collected from twelve cetacean species (n = 172) in the PRE from 2003 to 2020. Our results revealed medium levels of PCBs (316-96,233 ng g^-1 lipid) compared to those reported for cetaceans elsewhere (70-370,000 ng g^-1 lipid). Clear differences in PCB distribution patterns between inshore and offshore cetaceans and between odontocetes and mysticetes were also found. Both the coastal Indo-Pacific humpback dolphins (Sousa chinensis) and Indo-Pacific finless porpoises (Neophocaena phocaenoides) displayed similarly fine-scale spatial distribution patterns of PCBs, suggesting that the two cetaceans could serve as bioindicators of PCB pollution in the PRE. Additionally, both cetaceans exhibited decreasing trends in their blubber PCB concentrations over the past 20 years, likely reflecting the effective regulation of PCBs in the PRE Delta. Nevertheless, the relatively high and stable PCB-toxic equivalent (TEQ) levels detected in calf humpback dolphins during the sampling period suggested that the calves are still under the stresses of high PCB-related health risks. Our results highlight the need for more efforts to eliminate PCB contamination to prevent these cetaceans from continuous population decline and further extinction.

Temporal and spatial characteristics of PAHs in oysters from the Pearl River Estuary, China during 2015-2020

Estuary connects the inland freshwater and open seawater, which may become a sink for pollutants from land-derived outflows, especially for persistent organic pollutants (e.g., polycyclic aromatic hydrocarbons, PAHs). Due to complex fluctuation in estuary, it's difficult to achieve a comprehensive assessment of the pollution characteristics by grabbed environmental samples. Oysters serve as efficient biomonitors of pollution status in highly dynamic and anthropogenically impacted estuaries, like the Pearl River Estuary (PRE), South China. Here, we investigated the annual, seasonal, and spatial variations of PAHs in the soft tissues of oysters from the PRE over the last six years (2015-2020) and quantitatively analyzed the influence of environmental factors on PAH occurrence in the oysters. The concentrations of Σ₁₅PAH in oysters ranged from 74 to 1164 (337 ± 218) ng/g dry wt., with a peak occurrence in 2017. Highly seasonal and geographical variations in PAH pollution were documented in the PRE, with higher concentrations in oysters during the wet season than dry season, and in the eastern coast than western coast. Furthermore, geographical variation in PAH levels in the oysters was enhanced during the wet season, indicating a possible contribution of heavy rainfall flushing from the Pearl River. In addition to precipitation, water temperature and salinity also significantly influenced PAH levels in the oysters from the PRE by changing the bioavailability and biokinetics. Long-term biomonitoring using oysters in the current study reflected the pollution status and variation trends of PAHs in the highly dynamic PRE.

Distribution, Source and Potential Risk Assessment of Polychlorinated Biphenyls (PCBs) in Sediments from the Liaohe River Protected Area, China

This study aimed to assess the occurrence, distribution, toxicity equivalency and health risks of dl-PCBs (dioxin-like PCBs) from nine sites collected in surface sediments from Liaohe River Protected Area. ∑dl-PCBs concentrations in sediments range from 79.2 to 365.1 pg/g. Sediment profiles showed that pentachlorobiphenyl is the most abundant congener among all sampling sites. The results of principal component analysis and cluster analysis indicated that PCBs were mainly derived from electronic waste and paint additives in the sediments of Liaohe River Protected Area. Toxic equivalent quantity (TEQ) values of the PCBs in the Liaohe River Protected Area sediments are at comparatively lower levels compared with the previously reported data. Hazardous ratio (HR) for human health risk assessment allied to cancer was found to be lower than the non-carcinogenic risk assessment within an acceptable range.

Integrated transcriptomics and proteomics revealed the distinct toxicological effects of multi-metal contamination on oysters

The Pearl River Estuary (PRE) is the largest estuary in southern China and under high metal stress. In the present study, we employed an integrated method of transcriptomics and proteomics to investigate the ecotoxicological effects of trace metals on the Hong Kong oyster Crassostrea hongkongensis. Three oyster populations with distinct spatial distributions of metals were sampled, including the Control (Station QA, the lowest metal levels), the High Cd (Station JZ, the highest Cd), and the High Zn-Cu-Cr-Ni (Station LFS, with the highest levels of zinc, copper, chromium, and nickel). Dominant metals in oysters were differentiated by principal component analysis (PCA), and theirgene and protein profiles were studied using RNA-seq and iTRAQ techniques. Of the 2250 proteins identified at both protein and RNA levels, 70 proteins exhibited differential expressions in response to metal stress in oysters from the two contaminated stations. There were 8 proteins altered at both stations, with the potential effects on mitochondria and endoplasmic reticulum by Ag. The genotoxicity, including impaired DNA replication and transcription, was specifically observed in the High Cd oysters with the dominating influence of Cd. The structural components (cytoskeleton and chromosome-associated proteins) were impaired by the over-accumulated Cu, Zn, Cr, and Ni at Station LFS. However, enhanced tRNA biogenesis and exosome activity might help the oysters to alleviate the toxicities resulting from their exposure to these metals. Our study provided comprehensive information on the molecular changes in oysters at both protein and RNA levels in responding to multi-levels of trace metal stress.

Sources of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) found in surface sediment from coastal areas of Beibu Gulf: A reflection on shipping activities and coastal industries

The presence of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) was determined in the sediments of Beibu Gulf, a newly developing industry and port in South China, to evaluate whether the rapid development of coastal cities has accelerated the organic pollution in the region. The levels of PCBs and DDTs ranged from 1.17 to 8.00 ng g^-1 and ND (not detected) to 3.82 ng g^-1, respectively. The levels were higher in the east of Beibu Gulf than in the west, which influenced by the industrialisation and urbanisation in the east. Additionally, penta-PCBs were the dominant PCB congeners, which are related to shipping activities, and DDTs may have originated from the historical use of technical DDT. The levels of pp'-DDD and PCBs did not have the potential to cause ecological risks in Beibu Gulf; however, residues of DDTs were at relatively higher ecotoxicological levels, thereby having the potential to cause adverse biological effects.

Ecological risk and early warning of soil compound pollutants (HMs, PAHs, PCBs and OCPs) in an industrial city, Changchun, China

Soil ecological risk caused by compound pollutants is a topic that deserves increasing attention, and soil risk early warning is a more in-depth discussion on this topic. In this study, we collected soil samples from Changchun, a typical industrial city, and determined the contents of 13 heavy metals (HMs) (0.00 mg kg^-1-6380 mg kg^-1), 16 polycyclic aromatic hydrocarbons (PAHs) (0.00 mg kg^-1-27.7 mg kg^-1), 7 polychlorinated biphenyls (PCBs) (0.30 μg kg^-1-168 μg kg^-1), and 8 organochlorine pesticides (OCPs) (0.00 mg kg^-1-4.52 mg kg^-1). The soil ecological risks of compound pollutants were assessed. The results showed that PAHs were the greatest risk pollutants, followed by PCBs and HMs, and OCPs were the smallest risk pollutants. Most of the ecological risks of compound pollutants were classified as "moderate severity" level according to the (contamination severity index) CSI evaluation criteria. With the help of modern industrial economic theory, through the analysis of the annual accumulation of pollutants, it is possible to predict the future pollutant content in Changchun, and the soil risks could be forewarned. The results showed that if active measures were not taken to reduce the accumulation of PAHs in Changchun soil, the CSI-PAHs would be classified as "ultra-high severity" level in 2035.

Levels and profiles of persistent organic pollutants in breast milk in China and their potential health risks to breastfed infants: A review

Although some persistent organic pollutants (POPs) were prohibited or limited in use several decades ago, they are still frequently detected in the human body. The purpose of this study was to understand the levels and profiles of POPs in breast milk in China and assess their potential health risks among breastfed infants under six months of age. A literature review focused on China was performed for studies published from 2001 to 2020. The POP levels in breast milk along with other important variables were extracted, and then the average individual POP levels in breast milk were estimated. This review summarises the distribution of traditional and new POPs, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), legacy brominated flame retardants (BFRs), perfluorinated compounds (PFCs), and chlorinated paraffins (CPs) and reported notably high levels of short-chain chlorinated paraffins and 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) in breast milk. Although the levels of traditional POPs generally declined over time, especially p,p'-DDE and beta-hexachlorocyclohexane (β-HCH), women living in coastal areas, urban areas, and southern China still have a high body burden of certain POPs. In the present study, the estimated daily intake (EDI) of POPs through breastfeeding was used to evaluate the health risk for infants by comparing with acceptable levels. The findings suggested that infants born in coastal areas most likely suffered potential health risk from exposure to DDT, and the health risk of hexachlorobenzene (HCB) in infants in most nationwide regions remains a concern. More importantly, the EDI of PCBs for infants exceeds the safe limit on a national scale. Continuous surveillance of PCBs in breast milk is critical to evaluate the potential health effects on humans.

Ecological risk assessment of persistent organic pollutants (POPs) in surface sediments from aquaculture system

Organochlorinated pesticides (OCPs) and Polychlorinated biphenyls (PCBs) in the surface sediments from shrimp ponds in four regions of the northern part of the Central Java coast (namely Brebes, Tegal, Pemalang, and Pekalongan) were investigated. The highest concentration of ∑ OCPs was found in Brebes Regency, ranging from 68.1 ± 3.4 to 168.1 ± 9.8 μg kg^-1 dw. As indicated by the DDT ratio and chlordane ratio, the value suggested that those compounds may mainly originate from historical inputs rather than a recent application. The concentrations of Ʃ 7 indicator PCBs were determined, with the concentration ranged from 1.2 ± 0.7 μg kg^-1 dw (Pekalongan) to 2.2 ± 0.4 μg kg^-1 dw (Tegal). The most toxic PCB congener, PCB 118, was detected in all studied regions, with the highest proportion found in Tegal. Source analysis indicated that PCBs in the sediments mainly originated from Aroclor 1254 and Aroclor 1248. Compared to sediment quality guidelines (SQGs), some OCPs were found with concentrations which potentially posed an adverse effect. Our findings suggested that more attention should be paid to ensure sustainable shrimp culture facing such a risk of the OCPs and PCBs.

Dynamic transcriptome response in Meretrix meretrix to Aroclor 1254 exposure

Polychlorinated biphenyls (PCBs) are well-known persistent organic pollutants; they have toxic effects on the immune system, reproductive system, and endocrine system by changing the metabolism of the body. To elucidate the underlying molecular mechanism, the clam Meretrix meretrix was exposed to 10 and 1000 ng/L Aroclor 1254 and natural seawater (control). Samples from clams exposed to natural seawater and those exposed to Aroclor 1254 for 1 and 3 days were individually collected for transcriptome analysis. After assembly, more than 535,157 transcripts with a mean length of 949 bp and an N50 length of 1279 bp were obtained; a final set of 177,142 unigenes was generated. In the present study, 5101 differentially expressed genes were identified. The differentially expressed genes were related to detoxification metabolism, oxidative stress, immune response, and endocrine system disruption. Of these genes, under the Aroclor 1254 exposure, cytochrome P450 20A1 (2.06-4.46 folds), glutathione S-transferase (2.25-3.80 folds), multidrug resistance-associated protein 1-like (1.49-2.92 folds), peroxidase-like protein (1.33-4.26 folds), lysozyme (1.61-2.05 folds), bcl-2 like 1 protein (1.14-2.29 folds) and vitellogenin (1.09-1.19 folds) showed been significantly induced expressed. At the same time, some genes were down regulated, including cytochrome P450 2J5 (-1.20 ~ -2.86 folds), cytochrome P450 3A24 (-1.40 ~ -4.08 folds), C1q (-1.27 ~ -1.66 folds), Sulfotransferase (-1.51 ~ -1.84 folds), monocarboxylate transporter 10 (-1.30 ~ -4.70 folds), 3-beta hydroxysteroid dehydrogenase (-1.43 ~ -2.81 folds) and beta-galactosidase (-1.23 ~ -2.23 folds). Furthermore, it showed that the expression levels of CYP2J5, glutathione S-transferase, 3-beta hydroxysteroid dehydrogenase and beta-galactosidase had time responses and dose responses. The present study provided insights into the toxic effects of Aroclor 1254 exposure in M. meretrix.

Degradation of 3,3',4,4'-tetrachlorobiphenyl (PCB77) by dielectric barrier discharge (DBD) non-thermal plasma: Degradation mechanism and toxicity evaluation

Polychlorinated biphenyls (PCBs) are a kind of persistent organic pollutants (POPs) with stable chemical properties which can be enriched in a biological body for a long time. They are often carelessly released into natural environment and thus constantly posing a potential threat to human health. However, because of lack of effective ways of degrading PCBs, researchers are still striving to explore new approaches to remove them from the environment. In this work, we employed atmospheric-pressure non-thermal dielectric barrier discharge (DBD) plasma to treat 3,3',4,4'-tetrachlorobiphenyl (PCB77) in aqueous solution and investigated the removal efficiency under different DBD conditions using different discharging gases. As a result, we showed that He-DBD had the highest removal efficiency with hydroxyl radical playing the major role in the degradation, while O₂-DBD also gave rise to relatively high efficiency with ozone making an important contribution. After 2 min of treatments by He-DBD and O₂-DBD, over 75% of PCB77 was degraded with removal rate of 23.65 mg/L and 22.19 mg/L per minute, respectively. Besides, the toxicological evaluation for the DBD treatment was also provided, confirming that the PCB77 degradation products had negligible biotoxicity. This work therefore provides a new effective approach to treatment of persistent organic pollutants (POPs) in the environment.