Freshwater systems serve as important sources and transportation routes for marine microplastic pollution, and inadequate attention has been paid to this situation. Data on microplastic pollution of typical seagoing rivers in northern China are lacking. In the current study, we investigated the distribution and characteristics of microplastics in the main stream of the Haihe River, which flows through a metropolis with a high population density and level of industrialization and then flows into the Bohai Sea. The microplastic samples were collected by manta trawls with pore sizes of 333 μm, and the microplastic concentrations ranged from 0.69 to 74.95 items/m³. Fibers dominated in the surface water of the Haihe River; their shapes that were categorized as fibers, film, foam, fragments, and spheres, and contributed 17.4–86.7% of the total microplastics studied. The size distribution of the microplastics was concentrated in a range of 100–1000 μm, with 54.7% of the total sizes corresponding to the 333-μm trawl. Micro-Fourier transform infrared (μ-FT-IR) spectra showed that the main components were polyethylene, poly(ethylene-propylene) copolymer, and polypropylene. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) measurements revealed scratches, micropores, and cracks on the surfaces of the microplastics due to mechanical friction, chemical oxidation and degradation processes. The results of this study confirmed the high abundance and high diversity of microplastics in an urban river and indicated appreciable impacts from point-source inputs on the microplastic pollution, such as effluents from wastewater treatment plants (WWTPs).

We investigated the profiles and levels of perfluoroalkyl carboxylic acids in edible clams from five fishing sites in Japan (Hokkaido, Himakajima-Aichi, Atsumi-Aichi, Kyoto, and Kumamoto) and one site in Vancouver, Canada in 2017. The mean concentrations of perfluoroalkyl carboxylic acids with 6–15 carbon atoms (C6–C15) in edible clams from Japanese coastal waters ranged from 197 to 1757 pg/g wet weight, but were only 48 pg/g wet weight in clams from the site in Canada. Total perfluoroalkyl carboxylic acid concentrations in clams collected in Japanese waters were 4–40 times higher than concentrations in clams from Canada. Perfluorooctanoic acid (C8) contributed 53% of total perfluoroalkyl carboxylic acid concentrations in the clams from Japanese waters, which may be contaminated from terrestrial sources though river effluents, but was not detected in the clam samples from Canada. Principal component analysis separated shorter- and longer-chain perfluoroalkyl carboxylic acids, suggesting differing emission sources or environmental fate. Consumption of clams may be an exposure pathway of perfluorooctanoic acid in the Japanese population.

The occurrence of emergent contaminants, 24 polybrominated diphenyl ethers (PBDEs), di(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), di-n-octyl phthalate (DnOP), bisphenol A (BPA) and nonylphenol (NP), was investigated in sediments and fishes collected from the Tamsui River system to determine the factors that influence their distribution and their risk to aquatic ecosystems and human health. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in sediments were 1–955, ND-23570, <50–411, <50–430, ND-80, ND-<50, ND-<50, 1–144, 3–19624 μg/kg dw, respectively. The spatial-temporal distribution trends of these compounds in sediments could be attributed to urbanization, industrial discharge and effluents from wastewater treatment plants. The PBDE congener distribution patterns (BDE-209 was the dominant congener) in sediments reflected the occurrence of debromination of BDE-209 and the elution of penta-BDE from the treated products. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in fish muscles were 2–66, 17–1046, <10–231, <10–66, <30, ND-<30, ND-<30, 0.4–7 and 3–440 μg/kg ww, respectively. The species-specific bioaccumulation of these compounds by fish was found and four species particularly showed high bioaccumulation potential. BDE-47 was the predominant BDE congener in fish muscles, suggesting high bioavailability and bioaccumulation of this compound. The results of biota–sediment accumulation factors showed that BDE-47, 99, 100, 153 and 154 had relatively high bioavailability and bioaccumulation potential for some fish species. The ecological risk assessment showed that the concentrations of BPA and NP in sediments were likely to have adverse effects on aquatic organisms (risk quotients > 1). The human health risk assessment according to hazard quotients (HQs) and carcinogenic risks (CRs) revealed no remarkable risk to human health through consumption of fish contaminated with BDE-47, 99, 100, 154, 209, DEHP, BPA and NP.

Metal pollution has been associated with anthropogenic activities, such as effluents and emissions from mines. Soil could be exposure route of wild rats to metals, especially in mining areas. The aim of this study was to verify whether soil exposure under environmentally relevant circumstances results in metal accumulation and epigenetic modifications. Wistar rats were divided to three groups: 1) control without soil exposure, 2) low-metal exposure group exposed to soil containing low metal levels (Pb: 75 mg/kg; Cd: 0.4), and 3) high-metal exposure group exposed to soil (Pb: 3750; Cd: 6). After 1 year of exposure, the metal levels, Pb isotopic values, and molecular indicators were measured. Rats in the high-group showed significantly greater concentrations of Pb and Cd in tissues. Higher accumulation factors (tissue/soil) of Cd than Pb were observed in the liver, kidney, brain, and lung, while the factor of Pb was higher in the tibia. The obtained results of metal accumulation ratios (lung/liver) and stable Pb isotope ratios in the tissues indicated that the respiratory exposure would account for an important share of metal absorption into the body. Genome-wide methylation status and DNA methyltransferase (Dnmt 3a/3b) mRNA expressions in testis were higher in the high-group, suggesting that exposure to soil caused metal accumulation and epigenetic alterations in rats.

The present endocrine disrupting chemicals (EDCs) in wastewater effluents due to incomplete removal during the treatment processes may cause potential ecological and human health risks. This study evaluated the removal and uptake of seven EDCs spiked in two types of wastewater effluent (i.e., ultrafiltration and ozonation) and effluent cultivated with the freshwater green alga Nannochloris sp. In ultrafiltration effluent cultivated with Nannochloris sp. for 7 days, the removal rate of 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and salicylic acid (SAL) was 60%; but Nannochloris sp. did not promote the removal of other EDCs studied. The algal-mediated removal of E2, EE2, and SAL was attributed to photodegradation and biodegradation. Triclosan (TCS) underwent rapid photodegradation regardless of adding algae in the effluent with 63%–100% removal within 7 days. Triclosan was also found associated with algal cells immediately after adding algae, and thus the primary mechanisms involved were photodegradation and bioremoval (i.e., bioadsorption and bioaccumulation). After algal cultivation, TCS still has a bioaccumulation potential to pose high risks within the food web and the endocrine disrupting properties of the residual estrogens in the effluent are not eliminated. Algal cultivation can be exploited to treat wastewater effluents but the removal efficiencies of EDCs highly depend on chemical types.

Predicting the cotransport of functional microorganisms and heavy metals in porous media is essential to both bioremediation and pollutant risk assessment. In this study, batch and column experiments were conducted to explore the cotransport behaviors of functional bacteria (FA1) and heavy metals (Pb²⁺/Cd²⁺) in saturated sand media under different conditions. The sorption capacity of heavy metals on FA1 was much greater than that of the sand, while both FA1 and sand showed stronger affinity to Pb²⁺ than Cd²⁺. The surface properties, especially zeta potential, of the bacteria and sand were altered by metal adsorption. As a result, the co-existence of Pb²⁺ decreased the transport of FA1 more significantly than that of Cd²⁺, and the influence was more significant with higher heavy metal concentration. On the other hand, the co-existence of FA1 inhibited the mobility of Pb²⁺ and Cd²⁺ in most scenarios, except when the cotransport concentration of Pb²⁺ was 5 mg L⁻¹, and the inhibition was more pronounced for Pb²⁺ than Cd²⁺. Increase in metal concentrations decreased the FA1-associated Pb²⁺/Cd²⁺ in effluents due to the remarkable decrease in FA1 mobility, and free soluble Pb²⁺/Cd²⁺ became the major migration species. In addition, due to stronger attractive forces and affinity between Pb²⁺ and FA1, nearly all presorbed-Pb²⁺ by sand was remobilized by FA1 and transported mainly in FA1-associated form other than soluble Pb²⁺. Findings from this study indicated that the cotransport of biocolloids and heavy metals are highly sensitive to the ion type and concentration, and evaluation of their transport in the subsurface should be carefully carried out to avoid inaccurate estimations.

The effluents from nuclear mining processes contain relatively high content of radionuclides (such as uranium), which may seriously threaten the environment and human health. Herein, a novel adsorbent, porous hydroxyapatite, was prepared and proven highly efficient for removal of uranyl ions (U(VI)) given its high U(VI) uptake capacity of 111.4 mg/g, fast adsorption kinetics, and the potential stabilization of adsorbed U(VI). A nearly complete removal of U(VI) was achieved by porous HAP under optimized conditions. Langmuir model could well describe the adsorption equilibrium. The data fit well with pseudo-second-order kinetic model, suggesting that U(VI) adsorption is primarily attributed to chemisorption with porous HAP. Intraparticle diffusion analysis showed that the intraparticle diffusion is the rate-limiting step for U(VI) adsorption by porous HAP. After removal by porous HAP, the adsorbed U(VI) ions were incorporated into tetragonal autunite, which has a low solubility (log Ksp: −48.36). Our findings demonstrate that the porous HAP can effectively remediate uranium contamination and holds great promise for environmental applications.

Little information is available about the occurrence of neonicotinoid insecticides in surface water and sediment of the metropolitan regions around the rivers in China. Here we investigate the residual level of neonicotinoids in the Guangzhou section of the Pearl River. At least one or two neonicotinoids was detected in each surface water and sediment, and the total amount of neonicotinoids (∑₅neonics) in surface water ranged from 92.6 to 321 ng/L with a geometric mean (GM) of 174 ng/L. Imidacloprid, thiamethoxam and acetamiprid were three frequently detected neonicotinoids (100%) from surface water. As for the sediment, total concentration was varied between 0.40 and 2.59 ng/g dw with a GM of 1.12 ng/g dw, and acetamiprid and thiacloprid were the common sediment neonicotinoids. Western and Front river-route of the Guangzhou section of the Pearl River suffered a higher neonicotinoids contamination than the Rear river-route, resulting from more effluents of WWTPs receiving, and intensive commercial and human activities. Level of residual neonicotinoids in surface water was significantly correlated with the water quality (p < 0.01), especially items of pH, DO and ORP, and nitrogen and phosphorus contaminants. Compared with reports about residual neonicotinoids in water and sediment previously, the metropolitan regions of the Guangzhou could be confronted with a moderate contamination and showed serious ecological threats (even heavier than the Pearl Rivers). Our results will provide valuable data for understanding of neonicotinoids contamination in the Pearl River Delta and be helpful for further assessing environmental risk of neonicotinoids.

The spatial and temporal distribution of selected endocrine disrupting compounds (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol, and bisphenol A) in two coastal areas of the Iberian Peninsula (Ria de Vigo and Mar Menor lagoon) were evaluated for the first time. Seawater and sediment samples collected during spring and autumn of 2015 were analysed using greener extraction techniques and liquid chromatography-tandem mass spectrometry. The presence of branched isomers (4-tert-octylphenol and nonylphenol) and bisphenol A in almost all seawater and sediment samples demonstrated their importance as pollutants in the frame of water policy, while no concentrations of linear isomers (4-n-octylphenol and 4-n-nonylphenol) were found. Higher seawater levels were observed in Mar Menor lagoon, especially in spring, associated with wastewater treatment plant effluents and nautical, agricultural and industrial activities. Similar sediment concentrations were measured in both studied areas, being nonylphenol levels five times higher than those measured for the other EDCs. Experimental sediment–water partition coefficients showed a moderate sorption of target compounds to sediments. Risk quotients for water compartment evidenced a moderate risk posed by nonylphenol, considering the worst-case scenario. For sediments, moderate risk related to 4-tert-octylphenol and high risk to nonylphenol were estimated.

The wide use of antibiotics in aquaculture for prophylactic and therapeutic purposes can potentially lead to the prevalence of antibiotic resistance genes (ARGs). This study reports for the first time the profile of ARGs from effluents of coastal aquaculture located in South Jeolla province and Jeju Island, South Korea. Using quantitative PCR (qPCR), twenty-two ARGs encoding tetracycline resistance (tetA, tetB, tetD, tetE, tetG, tetH, tetM, tetQ, tetX, tetZ, tetBP), sulfonamide resistance (sul1, sul2), quinolone resistance (qnrD, qnrS, aac(6′)-Ib-cr), β-lactams resistance (blaTEM, blaCTX, blaSHV), macrolide resistance (ermC), florfenicol resistance (floR) and multidrug resistance (oqxA) and a class 1 integrons-integrase gene (intI1) were quantified. In addition, Illumina Miseq sequencing was applied to investigate microbial community differences across fish farm effluents. Results from qPCR showed that the total number of detected ARGs ranged from 4.24 × 10⁻³ to 1.46 × 10⁻² copies/16S rRNA gene. Among them, tetB and tetD were predominant, accounting for 74.8%–98.0% of the total ARGs. Furthermore, intI1 gene showed positive correlation with tetB, tetD, tetE, tetH, tetX, tetZ tetQ and sul1. Microbial community analysis revealed potential host bacteria for ARGs and intI1. Two genera, Vibrio and Marinomonas belonging to Gammaproteobacteria, showed significant correlation with tetB and tetD, the most dominant ARGs in all samples. Also, operational taxonomic units (OTUs)-based network analysis revealed that ten OTUs, classified into the phyla Proteobacteria, Cyanobacteria/Chloroplast, Bacteroidetes, Verrucomicrobia and an unclassified phylum, were potential hosts of tetracycline resistance genes (i.e., tetA, tetG, tetH, tetM, tetQ and tetZ). Further systematic monitoring of ARGs is warranted for risk assessment and management of antibacterial resistance from fish farm effluents.