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Species Sensitive Distribution for Aquatic Biota Exposed to Chlorpyrifos

Author: ChenBoYu
Tutor: ZhaoJinSong
School: Huazhong Agricultural University
Course: Environmental Science
Keywords: Species sensitivity distribution Chlorpyrifos 5% hazard concentration The proportion of the potential impact of Uncertainty Bootstrap Probability distribution
CLC: X174
Type: Master's thesis
Year: 2011
Downloads: 58
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Abstract

Species sensitivity distribution (species sensitivity distribution, SSD) is an extrapolation methods based on single-species tests, its application in the ecological risk assessment of pollutants formulation of environmental quality standards and pollution ecosystem in recent years has become a hot topic. In this study, select the widely use of chlorpyrifos for water environment increasingly serious of organic phosphorus pesticide pollution problem as an object of study, the use of its aquatic ecosystems of different trophic levels of biological species half effect concentration (median effective concentration, EC50), to establish based on logarithmic - logistic, logarithmic - normal, logarithmic - triangle, the distribution of aquatic organisms in Weber SSD model, test and evaluation of the model using probability plots and goodness-of-fit test methods, and application parameters Bootstrap on model parameters and model output 5% hazard concentration (危险 a concentration for 5% of the species, HC5) and the potential impact of the proportion of (potentially affected fraction, PAF) uncertainty analysis. From model selection point of view, the paper also discussed the uncertainty of the method to reduce the SSD, while small sample data to construct the SSD, and determine the to build SSD required minimum sample size. This study for the environmental management agencies of contaminated water environment for fast, scientific, ecological risk assessment, as well as to develop a reasonable, safe water quality standards provide a theoretical basis and method of support. The main results are as follows: (1) to determine the probability of the four SSD model probability plots and goodness of fit test results show that the selection of four cumulative function distribution can fit species sensitivity data. Based on the comparison of the Anderson-Darling (AD) test statistic to determine the distribution of the number - the triangle fits the data better, its parameters a = -2.2260 ± 0.4016, b = 3.8306 ± .1588, c = 2.9032 ± 0.0401. (2) according to the established logarithmic - triangle SSD model, prediction of chlorpyrifos HC5 value 0.1048μg / L, whereby to obtain the maximum concentration of the chlorpyrifos standard values ??(criteria maximum concentration, CMC) for 0.0524μg / L. The basis of chlorpyrifos of monitoring data and the number of the - triangle SSD model to predict the waters of the Bohai Laizhou Bay, Yibo Langa River the Preto River, and Bolong Yi River in chlorpyrifos PAF were 0.01%, 4.84%, 11.01%, 12.35%. Simple characterization of the the Bohai Laizhou Bay marine ecosystem of ecological risk is small; Yibo Langa River suffered less risky, but the need to strengthen the monitoring of the waters, and to prevent a higher risk of damage from happening; Preto and Bo Longyi The two water ecosystems suffered risky, should prohibit the use of chlorpyrifos. (3) model parameter uncertainty analysis showed that the four SSD model has a good sound. But the four SSD model output the HC5 and a PAF estimates there are obvious differences, model selection uncertainty caused by SSD. (4) In order to reduce the uncertainty of model selection using nonparametric Boostrap method to build chlorpyrifos SSD the predicted chlorpyrifos HC5 value 0.0700μg / L, CMC the value 0.0350μg / L. Forecast Yibo Langa River, the Preto River, and Bolong Yi River in chlorpyrifos PAF values ??were 7.00%, 16.00%, 16.00%. Chlorpyrifos in the waters of the Bohai Laizhou Bay PAF value is lower than the lower limit distribution the ecosystem ecological risk is very small. Compared with the the logarithm - triangle SSD model, the results obtained by the non-parametric Bootstrap method is more conservative. (5) based on the parameters Bootstrap method to determine the need at least nine different species acute toxicity data to build the SSD. Based on non-parametric Bootstrap method to determine the use of non-parametric Bootstrap build the the SSD required minimum sample size to 10.

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