Chemical- and species-specific toxicity of nonylphenol and octylphenol to microalgae Chlorella pyrenoidosa and Scenedesmus obliquus.

As typical endocrine disrupters, nonylphenol (NP) and octylphenol (OP) are emerging pollutants that have attracted wide attention. This study investigated the toxicity effects of NP and OP on microalgae Chlorella pyrenoidosa and Scenedesmus obliquus, particularly on their growth inhibition, photosynthetic pigment, chlorophyll fluorescence, and superoxide dismutase and malondialdehyde levels. Results showed that the 96 h EC50 of NP and OP was 2.89 and 5.21 mg/L on C. pyrenoidosa, respectively, and 1.54 and 8.48 mg/L on S. obliquus, respectively. NP exerted a stronger inhibitory effect on cell growth, photosynthesis, and PSII activity, and it contributed more oxidative stress on C. pyrenoidosa than on S. obliquus. By contrast, OP exerted a stronger inhibitory effect on S. obliquus than on C. pyrenoidosa. Furthermore, the toxicity of OP to the tested microalgae was lower than that of NP. Principal component analysis (PCA) and Pearson's correlation indicate that the accumulation of reactive oxygen species is the dominant mechanism of NP and OP cellular toxicity. The principal components of NP and OP affecting microalgae are distinct in the PCA plot, and different endocrine disrupters have varying chemical-specific influences on algal cells. This study confirmed that the toxicity of NP and OP to microalgae C. pyrenoidosa and S. obliquus is chemical- and species-specific. These findings should be considered when assessing the health risk of environmental pollution.

[Pollution assessment in the intertidal zone of Beibu Gulf using multi-biomarker pollution index].

This paper assessed the coastal environmental quality along the Beibu Gulf using a statistical approach, multi-biomarker pollution index (MPI). Samples of clam (Paphia undulata) and sediment were collected at nine sites from the intertidal zone of Beibu Gulf in April 2011. Nine biomarkers of response were measured both in gill and digestive gland in Paphia undulata, and twelve kinds of contaminants were measured in different sediment samples. According to the Pearson' s correlation coefficients between biomarker responses in Paphia undulata and contaminant levels in sediments, five biomarkers either in gill for oxidized glutathione (GSSG), reduced glutathione (GSH), glutathione S-transferase (GST) or in digestive gland for thiobarbituric acid reactive substances (TBARS) and glutathione peroxidase (GPx) were selected for MPI calculation. For each biomarker at each site, a response index was allocated, and the MPI value of this site was calculated as the sum of the response index of the five biomarkers. The results of the calculation (MPI values from 18 to 39) showed significant differences among sampling sites. The environmental quality of all sites ranged from class 1 (clean) to class 3 (lightly contaminated), and no site fell into class 4 (contaminated) or class 5 (heavily contaminated), indicating a good environmental quality in the intertidal zone of Beibu Gulf. However, the environmental quality at some sites (S1, S3, 54 and S7) fell into class 3 (lightly contaminated), indicating mild interference from human activities has occurred.