A Probabilistic Dose-Based Approach to Derive Site-Specific Environmental Quality Criteria for Farmed Abalone Haliotis diversicolor supertexta Exposed to Zinc
Date Issued
2005
Date
2005
Author(s)
Chou, Berry Yun-Hua
DOI
zh-TW
Abstract
The purpose of this thesis is to develop mechanistic models to accurately quantify environmental quality criteria (EQC) and to predict a risk threshold for the survival and growth of farmed abalone Haliotis diversicolor supertexta exposed to waterborne zinc (Zn) based on a probabilistic internal effect concentration (IEC)-based modeling framework. We couple a first-order two-compartment bioaccumulation model and a reconstructed dose-response profile based on a three-parameter Hill equation model associated with a field bioaccumulation study to form a probabilistic model to determine the risk threshold and the acute and chronic EQC based on a 10% probability of exceeding the abalone 10% IEC (IEC10) for site-specific abalone farms. Sensitivity analysis reveals that waterborne Zn concentration (Cw) and abalone depuration rate (k2) have a significant effect on Zn levels in abalone. Using a multiple nonlinear regression analysis with Cw and k2 as parameters, a predictive risk threshold equation that can be used with a variety of site-specific conditions was developed for the survival protection of farmed abalone. The acute EQC (a-EQC) is predicted from IECs and a field-derived bioaccumulation factors, whereas a statistical procedure with an acute-to-chronic value is used to derive chronic EQC (c-EQC) based on bioaccumulation. Field bioaccumulation study demonstrates a linear relationship between water and tissue Zn concentrations in abalone and algae. Our model, designed for simplicity and theoretical insight, yields explicit mathematical results through a probabilistic analysis to capture EQC modeling methodology in a more realistic way by analyzing computationally through Monte Carlo simulation technique that propagates parameter uncertainty/variability throughout the model, providing decision makers with credible range information and increased flexibility in establishing a specific Zn level in aquacultural ecosystems. Here we show that the median a-EQC range from 0.32 – 0.33μ g ml-1, whereas the median c-EQC are 0.047 – 0.048 µg ml-1 for selected abalone farms. We believe that this probabilistic dose-based framework is an effective method for conceptualizing a public policy decision vis-à-vis establishing a mechanistically-based site-specific acceptable acute and chronic EQC and a specific reasonable risk threshold for better management and restoration of the rapidly degrading aquacultural ecosystems.
Subjects
九孔
隨地域而變之環境品質標準
機率
風險
毒性門檻值
鋅
Abalone
Site-specific environmental quality criteria
Probabilistic
Risk
Toxicity threshold
Zinc
Type
thesis
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