tailieunhanh - Ecological Risk Assessment for Contaminated Sites - Chapter 2

Vấn đề Xây dựng Khi độ tuổi này có năng khiếu, trong giờ tối của nó, Rains từ bầu trời một trận mưa chóng của sự kiện . chúng nằm không thể hỏi, uncombined. Sự khôn ngoan đủ để ngấm chúng ta về bệnh của chúng tôi hàng ngày kéo thành sợi; nhưng có tồn tại không có khung cửi dệt nó thành vải . - Edna St Vincent Millay, Sonnet 137 "Vấn đề xây dựng là một quá trình xác định bản chất của vấn đề được giải quyết và quy định cụ thể việc đánh giá rủi ro cần thiết. | 2 Problem Formulation Upon this gifted age in its dark hour Rains from the sky a meteoric shower Of lie unquestioned uncombined. Wisdom enough to leach us of our ill Is daily spun but there exists no loom To weave it into fabric. Edna St. Vincent Millay Sonnet 137 Problem formulation is a process of defining the nature of the problem to be solved and specifying the risk assessment needed to solve the problem. In the poet s metaphor the problem formulation attempts to build and string a fact loom. The rest of the assessment process is fact weaving. The principal results of the problem formulation are the assessment endpoints a conceptual model of the induction of ecological risks on the site and an analysis plan. If the problem formulation is done in a haphazard manner the resulting assessment is unlikely to be useful to the risk manager. The process should be taken as seriously as the performance of toxicity tests or the creation of a hydrologic model and should be done with at least as much care. RISK MANAGERS AND RISK ASSESSORS The primary purpose of performing ecological risk assessments for contaminated sites is to provide information needed for a decision concerning remediation. Therefore the participation of the individuals who will make the decisions the risk managers is imperative. Many of the decisions made in the problem formulation involve values rather than facts and therefore are policy judgments rather than scientific decisions. There are several questions What should be protected What is the appropriate spatial and temporal scale What future scenarios are relevant What expressions of risk are useful for the decision However the form and extent of participation by risk managers are highly variable. There are at least three ways in which their participation can occur. First the risk manager may provide input prior to the problem formulation. This option is suggested by the EPA framework for ecological risk assessment which shows the risk