Pedosphere 17(4): 467--474, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Risk assessment of nitrogen discharge from a coastal watershed
CHEN Neng-Wang, HONG Hua-Sheng, ZHANG Luo-Ping and CAO Wen-Zhi
State Key Laboratory of Marine Environmental Science, Environmental Science Research Center, Xiamen University, Xiamen 361005 (China). E-mail:
      Probabilistic risk assessment (PRA) uses probability theory to quantify the probability of occurrence of an event. In this study, PRA was conducted for the discharge of excess nitrogen (N) from an agricultural (Jiulong River) watershed in Southeast China. Using fault tree analysis, a type of PRA, the probability of occurrence of excess N discharge into the river during a runoff event was evaluated both qualitatively and quantitatively. Land use maps, soil maps, fertilizer use records, and expert opinions were used to determine probabilities of individual events within the fault tree and to calculate the overall probability of excess N discharge during a runoff event. Qualitative analysis showed that the risk of excess N discharge was mainly related to crop and livestock practices in the watershed. Proper management of tillage, fertilizer, and manure was necessary to control N releases. Quantitative assessment results indicated that alternative practices including reduction of fertilization, installation of vegetative strip buffer around the pig farms, and installation of more riparian buffers along the Jiulong River could reduce the likelihood of N discharge through runoff.
Key Words:  N discharge, probabilistic risk assessment, runoff, watershed
Citation: Chen, N. W., Hong, H. S., Zhang, L. P. and Cao, W. Z. 2007. Risk assessment of nitrogen discharge from a coastal watershed. Pedosphere. 17(4): 467-474.
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