tailieunhanh - AQUATIC EFFECTS OF ACIDIC DEPOSITION - CHAPTER 8

Nghiên Cứu Về thực nghiệm thao tác Các giá trị khoa học và chính trị của nghiên cứu lĩnh vực thử nghiệm của quá trình axit hóa cũng đã được công nhận cho một số thời gian (Wright, 1991). Các nguồn khác của thông tin định lượng, bao gồm cả kết quả khảo sát, giám sát, nghiên cứu trong phòng thí nghiệm, và mô hình hóa không đủ, riêng của họ, như là một nền tảng cho sự hiểu biết và dự đoán các phản ứng axit hóa và phục hồi. Kết quả của cuộc khảo sát chất lượng nước ở. | 8__ Experimental Manipulation Studies The scientific and political value of experimental field studies of acidification processes have been well recognized for some time Wright 1991 . Other sources of quantitative information including survey results monitoring laboratory studies and modeling are insufficient on their own as a foundation for understanding and predicting acidification and recovery responses. The results of surveys of water quality in areas impacted by acidic deposition as well as areas not impacted by acidic deposition . Sullivan 1990 have been used for two decades as evidence of acidification effects. Interpretation of such data is always compromised however by differences between the impacted and unimpacted areas that are independent of acidic deposition. Such differences may include aspects of soils geology climate land use and hydrology that in some cases can overwhelm the effects of S or N deposition. Acidification of aquatic and terrestrial ecosystems operates on time scales of many years to many decades. There are few time series of monitoring data available with long enough period of record to confirm the validity of our understanding of key acidification processes. Furthermore interpretation of time series data is often uncertain because a variety of mechanisms can provide plausible explanations of observed responses. Concurrent changes in climate land use disturbance or other factors confound the interpretation of monitoring results. There has been a large increase during the past decade in the amount of experimental research being conducted on the environmental effects of atmospheric deposition especially of N. This research has been initiated mostly in Europe little comparable work has been conducted in the . The experimental approach has shifted heavily into the area of whole-ecosystem experimental manipulations that have been and are being conducted across gradients of atmospheric deposition .