Toxicity of the xenoestrogen nonylphenol and its biodegradation by the alga Cyclotella caspia

• Published in: Journal of environmental sciences (China) Vol. 25; no. 8; pp. 1662 - 1671
• Main Authors: Liu, Yu, Dai, Xiaokang, Wei, Jie
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2013
• Subjects: alkylphenol; aquatic environment; biodegradation; Biodegradation, Environmental; chlorophyll; Chlorophyll - metabolism; Chlorophyll A; Cyclotella; Cyclotella caspia; cytoplasmic inclusions; droplets; equations; estrogenic properties; Estrogens - metabolism; Estrogens - toxicity; industrialization; Kinetics; nonylphenol; Phenols - metabolism; Phenols - toxicity; Stramenopiles - enzymology; Stramenopiles - growth & development; Stramenopiles - metabolism; superoxide dismutase; Superoxide Dismutase - metabolism; surfactants; toxicity; 叶绿素a含量; 壬基酚; 小环藻; 有效浓度; 毒性; 生物降解实验; 超氧化物歧化酶活性; 雌激素; toxicity; biodegradation; alkylphenol; nonylphenol; Cyclotella caspia
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/S1001-0742(12)60182-X

Alkylphenols （APs）, the breakdown products of alkylphenol polyethoxylates that are widely used as surfactants, have been proven to exert estrogenic effects. With industrial development, higher concentrations of APs are discharged into aquatic environments. Nonylphenol （NP）, the most noxious AP, is included in the blacklist of several countries. The toxicity of NP to the alga Cyclotella caspia and the biodegradation of NP by C. caspia were studied in the laboratory. The median effective concentration at 96 hr （96 hr EC50 ） of NP for C. caspia was found to be 0.18 mg/L. Five toxicity and three degradation indices were selected for toxicity and biodegradation experiments, respectively, in five or three concentrations of NP set by the 96 hr EC50 of NP. The algal growth rate and chlorophyll a contents decreased as NP concentration increased. The main manifestations of morphological deformity of the cells included volume expansion and the presence of cytoplasmic inclusions （lipid droplets）. The abnormality rate of the cells increased with NP concentration and time, and was 100% at 0.22 and 0.26 mg/L of NP after 192 hr of culture. Superoxide dismutase activity initially increased and then declined at a higher NP toxicity of greater than 0.18 mg/L. After 192 hr of culture, the biodegradation rates of NP by C. caspia with initial concentrations of 0.14, 0.18, and 0.22 mg/L were 37.7%, 31.7%, and 6.5%, respectively. The kinetic equation of C. caspia biodegradation on NP was correlated with algal growth rate and initial NP concentration.