•Gill was more sensitive than hepatopancreas of Pinctada martensii exposed to DEHP.•GSH activity in the gill might be suitable biomarkers after DEHP exposure.•CAT activity in the hepatopancreas might be suitable biomarkers after DEHP exposure.Di(2-ethylhexyl) phthalate (DEHP) is recognized as one of the most ubiquitous contaminants in marine environments and causes adverse effects on the health of marine organisms. The purpose of this study was to investigate the toxic effects of DEHP on the pearl oyster Pinctada martensii. The Pinctada martensii was exposed to 0.0, 0.5, 2, 8, or 32 mg L−1 DEHP for 7 and 10 days using parameters of antioxidant. Antioxidant indicators included levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), peroxidase (POD), and total antioxidant capacity (T-AOC) in the gills and hepatopancreas of Pinctada martensii for 7 and 10 days. Besides, we used the lowest observed effect concentration (LOEC) of five enzyme activities in different tissues of Pinctada martensii for 7 and 10 days to compare sensitivity. The results showed that the gills were more sensitive than the hepatopancreas of Pinctada martensii and that GSH activity in the gills and CAT activity in the hepatopancreas might be suitable biomarkers after 7 days of DEHP exposure. After 10 days of DEHP exposure, the GSH activity and CAT activity in the gills and SOD activity in the hepatopancreas could be regarded as biomarkers. Compared to the LOEC, GSH activity in the gills and CAT activity in the hepatopancreas after 7 days of DEHP exposure were more sensitive than any other biomarkers. In addition, after 10 days of DEHP exposure, GSH activity in the gills and hepatopancreas were much more sensitive than other activities. In conclusion, GSH activity demonstrated its potential to be used as a biomarker for the monitoring of DEHP pollution in the marine environment.

Research on the kinetics of Benzo[a]pyrene (B[a]P) bioaccumulation in the clam Pinctada martensii and mussel Perna viridis showed that the initial rate of uptake was directly related to the PAH concentrations in the ambient environment. The uptake and depuration rate constants were different at the four B[a]P exposure levels, which indicated that the toxicokinetic rate constants mainly depended on the exposure levels of pollutants to the environment. In addition, the uptake rate constants of B[a]P were higher than the depuration rate constants in the entire experiment. The comparison demonstrated that mussels release B[a]P more rapidly than clams. The bioconcentration factors (BCFs) of B[a]P varied from 3335 to 12892 in the clam and 2373–6235 in the mussel. These findings on the bioaccumulation kinetics for petroleum hydrocarbons, in association with the critical body residue, will be valuable when choosing sensitive organisms to assess the potential ecotoxicological risk to the marine environment.

Acute toxicity, bioaccumulation, and elimination of herbicide clomazone in the earthworm Eisenia fetida were investigated in the different exposure systems. The LC50 values of clomazone on earthworms were 5.6 μg cm−2 in the contact filter paper test (48 h), 174.9 mg kg−1 (7 days) and 123.4 mg kg−1 (14 days) in artificial soil test, respectively. Clomazone could rapidly bioaccumulate in earthworms and reached the highest concentration after 3 days exposure, with the maximum concentrations of 9.0, 35.3 and 142.3 mg kg−1 at 10.0, 40.0 and 160.0 mg kg−1 of clomazone, respectively. Clomazone uptake showed a good correlation with exposure concentration. After the 14th day, clomazone declined to minimum value. About 74 %–80 % of accumulated clomazone was eliminated within 1 day after exposed to clomazone-free soil. However, a trace amount of clomazone persisted for a relatively long time in earthworms.

Pyrene, a typical polycyclic aromatic hydrocarbon, is a common pollutant in the marine environment. Polycyclic aromatic hydrocarbons initiate cellular detoxification in an exposed organism via the activation of the aryl hydrocarbon receptor (AhR). Subsequent metabolism of these xenobiotics is mainly by the cytochrome P450 enzymes of the phase I detoxification system. Full-length complementary DNA sequences from the pearl oyster Pinctada martensii (pm) encoding AhR and cytochrome P4 were cloned. The P. martensii AhR complementary DNA sequence constitutes an open reading frame that encodes for 848 amino acids. Sequence analysis indicated PmAhR showed high similarity with its homologues of other bivalve species. The cytochrome P(CYP)4 complementary DNA sequence of P. martensii constitutes an open reading frame that encodes for 489 amino acids. Quantitative real-time analysis detected both PmAhR and PmCYP4 messenger RNA expressions in the mantle, gill, hepatapancreas and adductor muscle of P. martensii exposed to pyrene. The highest transcript-band intensities of PmAhR and PmCYP4 were observed in the gill. Temporal expression of PmAhR and PmCYP4 messenger RNAs induction was observed in gills and increased between 3 and 5 days post exposure; then returned to control level. These results suggest that messenger RNAs of PmAhR and PmCYP4 in pearl oysters might be useful parameters for monitoring marine environment pyrene pollution.

The hydrolysis and photolysis of clomazone in aqueous solutions and natural water were assessed under natural and controlled conditions. Kinetics of hydrolysis and photolysis of clomazone were determined by HPLC-DAD. Photoproducts were identified by HPLC-MS. No noticeable hydrolysis occurred in aqueous buffer solutions ((25±2)°C, pH (4.5±0.1), pH (7.4±0.1), pH (9.0±0.1); (50±2)°C, pH (4.5±0.1), pH (7.4±0.1)) or in natural water up to 90 d. At pH (9.0±0.1) and (50±2)°C the half-life of clomazone was 50.2 d. Clomazone photodecomposition rate in aqueous solutions under UV radiation and natural sunlight followed first-order kinetics. Degradation rates were faster under UV light (half-life of 51–59 min) compared to sunlight (half-life of 87–136 d). Under UV light, four major photoproducts were detected and tentatively identified according to HPLC-MS spectral information such as 2-chlorobenzamide, N-hydroxy-(2-benzyl)-2-methylpropan-amide, 2-[2-phenol]-4,4-dimethyl-3-isoxazolidinone and 2-[(4,6-dihydroxyl-2-chlorine phenol)]-4,4-dimethyl-3-isoxazolidinone. These results suggested that clomazone photodegradation proceeds via several reaction pathways: 1) dehalogenation; 2) substitution of chlorine group by hydroxyl; 3) cleavage of the side chain. Photosensitizers, such as H2O2 and riboflavin, could enhance photolysis of clomazone in natural sunlight. In summary, we found that photoreaction is an important dissipation pathway of clomazone in natural water systems.

•Pyrene caused a significant decrease in THC, CMS, PA and GSHT.•Pyrene caused a significant increase in LPO.•There exists the dose-effect relationship in immune response and oxidative stress.•Pyrene has the subtle effects and potential risk for marine invertebrates.Pyrene is a polycyclic aromatic hydrocarbon (PAH) commonly observed in aquatic ecosystems, which originates primarily from the incomplete combustion of fossil fuels and the use of petroleum compounds. Pyrene can cause the immune disturbance and oxidative stress, result in immunotoxicity, DNA damage, reduce reproduction significantly, and induce behavioral changes. Marine bivalves are commonly used as bioindicators for marine pollution, and hemolymph is a metabolite transfer medium for PAH pollutant. However, the vital immune indicator responses of pearl oyster Pinctada martensii hemolymph exposed to pyrene is still unclear. Thus, the immunotoxic responses of pyrene on the hemolymph of the Pinctada martensii were investigated in this study. After exposure to pyrene for 7 days, the total number of hemocytes (THC), cell membrane stability (CMS), phagocytic activity (PA) and total glutathione (GSHT) all decreased significantly. Pyrene also caused a significant increase in lipid peroxidation (LPO). Median effective concentrations (EC50) of pyrene on THC (4.5 μg L−1) and LPO (5.2 μg L−1) were lower than those for CMS (13.8 μg L−1), PA (12.1 μg L−1) and GSHT (7.2 μg L−1), which indicates that THC and LPO were more sensitive. Additionally, a clear dose-effect relationship indicated that pyrene stimulated a marked immune response, as well as oxidative stress in P. martensii, which demonstrates the subtle effects of pyrene exposure on marine invertebrates and the potential associated risk.

•The status and composition of 16 US EPA priority PAHs in surface sediment were studied.•The primary sources of PAHs in surface sediment were vehicle emissions, petroleum products and biomass combustion.•The risk assessment implied that several PAHs would potentially affect organisms in most of the sites in Yangpu Bay.The study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the surface sediment from eleven sites in Yangpu Bay, China in December 2013 (winter) and July 2014 (summer). The 16 US EPA priority PAHs were found in the range of 1583.2–5701.7 ng/g dry weights with an average of 3134.7 ± 1241.3 ng/g in winter and ranged from 2161.8 to 4527.2 ng/g with an average of 3016.6 ± 748.0 ng/g in summer, respectively. The concentrations of the PAHs tended to be relatively high in comparison with other areas from the literatures. The identification using molecular indices analysis indicated that the PAHs originated mainly from pyrogenic and petrogenic sources in most of the sites. According to principle component analysis–multiple linear regression (PCA/MLR) for their source apportionment, the main sources of PAHs were vehicle emissions, petroleum products and biomass combustion. The risk assessment using international sediments quality guidelines and sediments quality criteria indicated that several PAHs, such as Nap, Flu, Phe, Ace, Acy and BghiP in most of the sites would potentially affect organisms in Yangpu Bay.

•The total PAHs concentrations ranged from 420.2 to 2539.1 ng L−1 with the average value of 1016.3 ± 455.8 ng L−1.•PAHs displayed spatial and temporal variations in the concentration and composition pattern.•PAHs mostly originated from petroleum and combustion process.•The potential risk of individual PAHs had reached moderate to high levels.Spatial and temporal distributions of 14 polycyclic aromatic hydrocarbons (PAHs) were investigated in surface waters of Haikou Bay, China from October 2013 to September 2014. The total PAHs concentrations ranged from 420.2 to 2539.1 ng L−1 with the average value of 1016.3 ± 455.8 ng L−1, which were predominated by low molecular weight PAHs (2- and 3-ring PAHs). Moreover, PAHs displayed spatial and temporal variations in the concentration and composition pattern. Source analysis based on isomer ratios indicated that the PAHs mostly originated from petroleum and combustion processes. An eco-toxicological risk assessment showed that the potential risk of individual PAHs had reached moderate to high levels and the total concentrations of PAHs had also reached a relatively high level compared with previous studies. This study offers important information on the pollution levels of 14 PAHs in the surface waters of Haikou Bay and recommends that prevention and control of PAHs pollution should be implemented in the region.

•The status and composition of fourteen PAHs in surface seawater were studied.•PAHs displayed spatial and temporal variations in the concentration and composition pattern.•The primary source of PAHs in surface seawater was petrogenic contamination.•The potential ecological risk of individual PAHs had reached moderate to high levels.The occurrence of 14 polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency was investigated in surface seawater of Yangpu Bay, China in November 2013 (winter) and May 2014 (summer). Seventy-two samples were collected from 12 sampling sites. The total concentrations of PAHs in Yangpu Bay showed obvious variations in different seasons, which varied from 582.8 to 2208.3 ng L−1 in winter and 952.4 to 1201.7 ng L−1 in summer, respectively. Two-ring PAHs accounted for more than 91.6% of total PAHs in winter, and three-ring PAHs were dominant with 81.6% of total PAHs in summer. Molecular indices analyses indicated that the main source of PAHs in Yangpu Bay could be petrogenic contamination. The ecological risk assessment by Risk quotients (RQNCs and RQMPCs) showed a potential ecological risk of PAHs in Yangpu Bay, indicating a close attention should be paid to pollution of PAHs in the coastal area of Yangpu.