Author
|
Submitted to: International IUPAC Symposium on Mycotoxins and Phycotoxins
Publication Type: Abstract Only Publication Acceptance Date: 4/30/2005 Publication Date: 8/12/2005 Citation: Wauchope, R.D. Field studies and modeling approaches for predicting entry of contaminants into surface waters. Proc. 40th Internat. Congress IUPAC, Beijing, August 12-21, 2005. Interpretive Summary: Technical Abstract: Consumption and contamination of surface and groundwater by agriculture may put farming in conflict with other human and ecological needs for the same resource. Some water contamination is accidental, or the result of human error. However, even if such incidents were eliminated, proper and correct use of tillage, fertilizers and pesticides can lead to contamination of waters with sediment and chemicals. Surface waters are particularly vulnerable because rainfall runoff, and resulting erosion of soil, generates sediment and sediment-borne chemical contamination as well as contamination by those soluble and soil-mobile chemicals which leach to groundwater. In the US this problem is particularly important because many or our agricultural areas are in a warm humid climate subject to intense rainstorms. US research to find technical solutions to this problem—generally referred to as “agricultural nonpoint pollution”--is about 40 years old for chemical pollution and over 60 years old for soil erosion. The story of how this research has evolved from field observation to regression analysis to simulation modeling is a fascinating one. Observation has defined theory which has defined computer algorithms, but at each step new information needs gleaned and new questions raised have been reflected backward. Modeling exposes gaps in theory which define the next experiments needed, so that theory and field research are clarified and focused. All three activities continue because the system studied is so complex and because all aspects of the system—climate, agricultural technology, field methology, and computer technology--are changing. This presentation will describe current research directions: (1) attempts to extrapolate field-scale process modeling to heterogeneous watersheds including riparian areas, impoundments and wetlands, up to and including large river basins; (2) a wide range of new nonagricultural chemical contaminant species resulting from human activities is being reported (3) the results of a series of very large-scale monitoring projects are being subjected to regression analysis (4) the stochastic nature of weather as the driver of nonpoint pollution is being incorporated into analyses by using probabilistic methods (5) the effectiveness of soil and water conservation practices, as practiced by US farmers on a wide scale, will be assessed by the use of models over a range of scales. |
