Microplastics in oysters Saccostrea cucullata along the Pearl River Estuary, China.

As a transitional zone between riverine and marine environments, an estuary plays an important role for the sources, accumulation and transport of microplastics. Although estuarine environments are hotspots of microplastic pollution, the correlation between microplastic pollution and aquatic organisms is less known. Here we investigated microplastic pollution in wild oysters Saccostrea cucullata from 11 sampling sites along the Pearl River Estuary in South China. The microplastic abundances in oysters ranged from 1.4 to 7.0 items per individual or from 1.5 to 7.2 items per gram tissue wet weight, which were positively related to those in surrounding waters. The oysters near urban areas contained significantly more microplastics than those near rural areas. Fibers accounted for 69.4% of the total microplastics in oysters. Microplastic sizes varied from 20 to 5000 µm and 83.9% of which were less than 100 µm. Light color microplastics were significantly more common than dark color ones. Based on the results, oysters are recommended as a biomonitor for the microplastic pollution in estuaries.

2-chlorophenol induced ROS generation in fish Carassius auratus based on the EPR method.

In the present study, a secondary spin trapping technique was used followed by electron paramagnetic resonance (EPR) analysis, to study the potential of reactive oxygen species (ROS) production after fish (Carassius auratus) were injected i.p. with different doses (50, 100, 200, 250, 500mgkg(-1)) of 2-chlorophenol (2-CP). The ROS signal intensity of the EPR spectrum showed a significant increase (p<0.05, compared with the control) when the 2-CP dose was as low as 50mgkg(-1). There is a good relationship between the 2-CP administered doses and ROS generation. Based on the hyperfine splitting constants and shape of the EPR spectrum, the ROS which was generated in fish liver after intraperitoneal (i.p.) injection of 2-CP was identified as ()OH. SOD and CAT activities were found to be induced at lower doses of 2-CP. GSH levels fell below the control level following all treatments with 2-CP, and GSSG levels changed along with those of GSH. These observations indicated that the fish experienced oxidative stress. The strong positive correlation (r=0.966, p<0.005) between ()OH radical and lipid peroxidation suggested that lipid peroxidation was possibly induced by ()OH. The phase II detoxification enzyme glutathione-S-transferase (GST) may play an important role in 2-CP metabolism or excretion and, consequently, reduce ROS production. This study provides strong evidence that level of ROS is significantly increased in 2-CP stressed fish, and ROS may serve as a potential biomarker to indicate 2-CP contamination.

Electron paramagnetic resonance investigation of in vivo free radical formation and oxidative stress induced by 2,4-dichlorophenol in the freshwater fish Carassius auratus.

In the present study, electron paramagnetic resonance coupled with spin-trapping technique was used, with alpha-phenyl-N-tert-butylnitrone (PBN) as a spin-trapping agent, to investigate free radical generation in freshwater fish with acute 2,4-dichlorophenol (2,4-DCP) poisoning. The PBN-radical adducts were detected in fish liver samples following treatments of 2,4-DCP (0.025, 0.05, 0.5, 5, or 25 mg/kg) 24 h after intraperitoneal (i.p.) injection and 2,4-DCP (0.5 mg/kg) at 2, 4, 8, 24, or 72 h after i.p. injection in Carassius auratus. The hyperfine splitting constants for the PBN-radical adducts are aN = 13.7 G, aH = 1.8 G, and g = 2.0058, which is consistent with those of PBN/hydroxyl radical (*OH). The results indicate that the hydroxyl radical is probably produced during acute intoxication of 2,4-DCP. The relative similarity in the kinetics (from 2 to 72 h) of superoxide dismutase activity induction and *OH generation implies that the generation of *OH possibly depends on the superoxide anion (O2*-). Superoxide anion (O2*-) might be the precursor radical undergoing the Haber-Weiss reaction to form *OH. Possible pathways for radical chain reactions in the formation of the hydroxyl radical in vivo after 2,4-DCP administration are proposed. Other parameters with respect to antioxidant defense (e.g., superoxide dismutase and catalase) and oxidative damage (lipid peroxidation level) indicate that the fish were subjected to oxidative stress induced by 2,4-DCP and that the mechanisms of oxidative stress possibly involve the in vivo stimulation of hydroxyl radical formation.

[Occurrence and distribution of organotin compounds in Thais clavigera from Xiamen coast].

Occurrence and distribution of 6 organotin compounds including butyltin and phenyltin species were detected in Thais clavigera which were collected from 9 coastal areas sites around Xiamen Coast, by pentylized derivatization, GC-FPD. Results indicated that all Thais clavigera samples were contaminated with organotin compounds. The concentrations in Thais clavigera soft bodies varied from 0.3 to 70.6 ng x g(-1) with a mean value of 28.8 ng x g(-1) for butyltin compounds, and from nd to 18.8 ng x g(-1) with a mean value of 7.9 ng x g(-1) for phenyltin compounds, respectively. MBT and TPhT were high levels in butyltin compounds and phentyltin compounds, respectively. In addition, butyltin compounds were the dominant contaminates in all samples with high percentage from 74.3% to 96.8%. There was a significant correlation between TBT and TPhT (R2=0.7109, p<0.01). This result showed that both TBT and TPhT came from antifouling paints for ships or for mariculture nets. Compared with those data reported from the other regions around southeast coast of China, present study reveals that contaminated level of organotin compounds in Thais clavigera are relatively lower in Xiamen Coast. But it is higher than those in 2002.

[Free radical generation and lipid peroxidation induced by 2,4-dichlorophenol in liver of Carassius auratus].

Free radical generation in liver of larval fish (Carassius auratus) after 2,4-dichlorophenol (2,4-DCP) injected intraperitoneally 24 h was studied with electron paramagnetic resonance (EPR) spin trapping technique and alpha-phenyl-N-tert-butylnitrone (PBN) as spin trap reagent. The results show that there is a significant increase of free radical generation in the liver of the fish treated with 2,4-DCP (0.025, 0.05, 0.5, 5, 25 mg/kg) compared with that of the control (p<0.05). The free radical generation correlates well with the dose of 2,4-DCP administered. The regress equation for dose-effect relation is y = 1189ln(x) + 9220, r2 = 0.9856. The six-line composed of three groups with two hyperfine splitting peaks in each shows a typical PBN/*OH EPR spectrum. The hyperfine splitting constants for the PBN-adducts is alphaN = 13.7 Gauss, alphaH= 1.8 Gauss, g factor is 2.0058, which is consistent with the characteristics of PBN-hydroxyl radical adduct reported from the literature. Results also show that there is a significant increase for malondialdehyde (MDA) content in the treated groups compared with that of the control (p<0.05). The mechanisms of free radical generation and lipid peroxidation induced by 2,4-DCP are discussed in this study.