Simultaneous Assessment of Deposition Effects of Base Cations, Sulfur, and Nitrogen Using an Extended Critical Load Function for Acidification

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• 作者：Yu Zhao ; Lei Duan ; Thorjorn Larssen ; Lanhua Hu ; Jiming Hao
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：March 15, 2007
• 年：2007
• 卷：41
• 期：6
• 页码：1815 - 1820
• 全文大小：304K
• 年卷期：v.41,no.6(March 15, 2007)
• ISSN：1520-5851

文摘

Base cations (BC) play an important role to prevent soilacidification. In certain acid sensitive areas, such as China,BC deposition is high and a considerable fraction is ofanthropogenic origin. BC deposition might decrease in thefuture with the implementation of air pollution controlmeasures. The effect of changes in BC deposition, however,has seldom been considered in critical load calculationsbased on the steady-state mass balance (SSMB) method. Inorder to better quantify the importance of the BC depositionfor acid deposition mitigation policy, an extension ofthe SSMB method for critical load calculation for soilacidification is presented. The BC deposition is taken intoaccount as a variable along with sulfur (S) and nitrogen(N) deposition, creating an S-N-BC critical load function.As a case study, critical loads of S and N for the TieShan Ping catchment in Chongqing in southwest Chinaunder variable BC deposition were calculated. Results indicatethat abatement of BC deposition has significant impacton the critical loads of S and N. A 75% reduction in BC ofassumed anthropogenic origin decreases the criticalloads of acids by 58%. The current deposition does notexceed the critical loads, but if BC deposition fromanthropogenic sources was controlled, then the exceedancewould be considerable. Uncertainty analysis show thatthe size of the BC deposition of natural origin is the singleparameter contributing the most to the steady-state Sand N critical load. The extended critical load function canbe used by policy makers to set more reasonable aciditycontrol strategies in the future. The method also highlightsfor policymakers the "competition" between emissioncontrol of particulate matter driven by human health targetsand potential increase of net acid load from such measures.