科研之友
微信
新浪微博
Facebook
分享链接
摘要
In life cycle assessment (LCA), the freshwater eutrophication potential (EP) of agricultural systems is difficult to assess. In common practice, the EP is assessed using release factors that reflect average soil and receiving water conditions in a particular region, typically Western Europe. Local conditions are highly variable, and generic release factors do not provide an accurate assessment in locations where conditions deviate significantly from the average conditions in Western Europe. We present a method to assess the freshwater EP of phosphorus discharge from agricultural systems using estimates of annual phosphorus loss and phosphorus loss reduction due to flow through riparian zones. The method combines an annual phosphorus loss estimator, the Revised Universal Soil Loss Equation (RUSLE), the runoff curve number, and a simple riparian zone model; which together represent the most important mechanisms controlling the release of P from agricultural systems. All required data are publicly available. The method is evaluated by comparing its predictions with reference results from five test cases derived from three studies that used calibrated and validated process-based modeling tools to estimate phosphorus loss. Results of a common LCA impact method (i.e. using a site-generic factor) are also compared with the reference studies. Relative to the estimates of the detailed reference studies, the predictions of a common LCA method were inaccurate (percent relative error up to -86%), showing significant underestimation (percent bias = 79), and a root mean square error to observations standard deviation ratio (RSR) of 2.17. The proposed method reproduced the reference studies' predictions with a lower percent relative error (less than 27%), a relatively small underestimation (percent bias = 5.2%), and a significantly reduced error (RSR = 0.38). Predictions from the proposed method are significantly better correlated, as quantified by the coefficient of determination (RSQ), with the reference values (RSQ = 0.869) than those from using a site-generic factor (RSQ = 0.001). The evaluation indicated that the proposed method provides more accurate estimates of EP from agricultural use of phosphorus than the common practice of using a site-generic factor. Because the method uses simple equations based on the factors governing phosphorus loss, it is easily integrated into LCA and provides more accurate and reliable estimates of freshwater eutrophication potential from agricultural use of phosphorus.
- 出版日期2018-3-10
