tailieunhanh - AQUATIC EFFECTS OF ACIDIC DEPOSITION - CHAPTER 5

Định lượng hóa chất liều-đáp ứng mối quan hệ Hiện đã có được một sự công nhận quốc tế không khí ảnh hưởng ô nhiễm, đặc biệt từ S và N, có thể trong một số trường hợp đòi hỏi phải kiểm soát khí thải để giảm hoặc hạn chế sự gia tăng trong tương lai lắng đọng khí quyển. Các biện pháp giảm lượng khí thải phải dựa trên ước tính liều đáp ứng các mối quan hệ phản ánh khả năng chịu đựng của hệ sinh thái tự nhiên cho các đầu vào khác nhau của các chất gây. | 5 Chemical Dose-Response Relationships and Critical Loads Quantification of Chemical Dose-Response Relationships There has been a growing international recognition that air pollution effects particularly from S and N may in some cases necessitate emission controls to reduce or limit future increases in atmospheric deposition. Measures to reduce emissions must rely on known or estimated dose-response relationships that reflect the tolerance of natural ecosystems to various inputs of atmospheric pollutants. This need has stimulated interest in evaluating the efficacy of establishing one or more standards for acid deposition. The Clean Air Act Amendments of 1990 CAAA also included requirements to assess the effectiveness of the mandated emissions controls via periodic assessments and to submit an EPA report on the feasibility of adopting one or more acid deposition standards to Congress. Diverse data are available from a variety of sources with which to quantify the watershed acidification response as well as recovery from acidification. Such data shed light on the sensitivity of various kinds of watershed systems to changes in acidic deposition. Intercomparisons among the various studies that have been conducted are complicated by different relative watershed sensitivities S deposition loading rates and changes in those rates the relative importance of N leaching and N saturation temporal considerations and natural especially climatic variability. In addition these quantitative data have been generated in vastly different ways including monitoring space-for-time substitution whole-watershed or whole-lake acidification wholewatershed acid exclusion paleolimnology and modeling. The only way in which different approaches can be compared on a quantitative basis is by normalizing surface water response as a fraction of the change in SO42- concentration or SO42- NO3- concentration where NO3- is also important . The principal ions .