tailieunhanh - Freshwater Bivalve Ecotoxoicology - Chapter 6

Trong thử nghiệm độc tính Situ của Unionids Khi chú ý nhiều hơn quy định là cho việc ra quyết định dựa trên rủi ro, trong dòng các cuộc điều tra và thử nghiệm độc tính tại chỗ nhanh chóng trở thành quan trọng hơn trong lĩnh vực pháp lý (Karr và Chu 1999). Điều này thể hiện một sự thay đổi đáng kể từ phương pháp tiếp cận truyền thống của quy định bằng cách đáp ứng tiêu chí cụ thể. Thử nghiệm độc tính truyền thống được sử dụng để đánh giá nồng độ của một chất hóa học. | 6 In Situ Toxicity Testing of Unionids Mindy Yeager Armstead and Jessica L. Yeager INTRODUCTION As more regulatory attention is given to risk-based decision making in-stream surveys and in situ toxicity testing are rapidly becoming more important in the regulatory arena Karr and Chu 1999 . This represents a dramatic change from the more traditional approach of regulation by meeting specific criteria. Traditional toxicity testing is used to evaluate the concentrations of a given chemical and the duration of exposure required to produce the criterion effects Rand 1995 . This type of testing has been used extensively for evaluating the potential in-stream impacts of discharges and for setting discharge limits or exposure concentrations that protect organisms and communities from chemical stressors Webber 1993 . Traditionally toxicity tests have been designed to evaluate lethal or sub-lethal endpoints that indicate impairment to aquatic organisms or communities . growth reproductive impairment and reduced diversity or to measure bioaccumulation which may or may not be associated with adverse effects Rand 1995 . Much effort has gone into the standardization of toxicity testing methodologies from the culturing of organisms used in testing to the statistical analyses used to determine significant impacts. Standardization is important for ensuring that the stressor being evaluated is responsible for any effects identified and not for organism health laboratory personnel error food of poor nutrient value substandard water temperature stress dirty glassware or any number of variables that can contribute to impairment in test organism performance. Minimizing the test variability enhances the confidence in the cause and effect relationship being demonstrated between the stressor and the response. The benefits of minimizing laboratory toxicity test variability are significant and these tests have many applications however the results do not always extrapolate to in situ .