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| Characteristics of production-consumption balance and environmental loads of nitrogen in food chain system in Changshu City |
| Received:January 29, 2016 |
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| KeyWord:nitrogen;food chain system;production-consumption balance;environmental load |
| Author Name | Affiliation | E-mail | | ZHANG Ning | School of Geography Science, Nanjing Normal University, Nanjing 210023, China | | | WANG Yan-hua | School of Geography Science, Nanjing Normal University, Nanjing 210023, China
Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023, China | wangyanhua@njnu.edu.cn | | YANG Hao | School of Geography Science, Nanjing Normal University, Nanjing 210023, China
Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023, China | | | ZHOU Wei | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | CAI Zu-cong | School of Geography Science, Nanjing Normal University, Nanjing 210023, China
Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing 210023, China | |
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| Abstract: |
| Changshu is a developed city in the Taihu Lake Region with intensive agriculture and dense population. It was reported that nitrogen was primary pollutant of the surface water in Changshu City. To understand the characteristics of nitrogen flows in Changshu food chain system, a nitrogen flow model in food chain system was constructed. The model was then applied to calculate the nitrogen fluxes in crop production subsystem, livestock breeding subsystem and household consumption subsystem of Changshu City from 2000 to 2013. The characteristics of production and consumption balance and environmental loads of nitrogen were finally analyzed. Results showed that plant-derived food nitrogen had an average annual surplus of 2 171.54 t·a-1 from 2000 to 2013. Animal-derived food nitrogen showed a little surplus of 47.71~56.92 t from 2000 to 2002. From 2003 to 2013, however, animal-derived food nitrogen was short of 210.03 t·a-1. The food chain system lost 23 382.70 t N·a-1 into the environment. The loss rates of three subsystems were 65.39%, 69.03% and 68.16% for crop production, livestock breeding and household consumption subsystems, respectively. The lost nitrogen caused an environmental load of 18 101.95 t N·a-1, 40.33% of which was transported into water, 29.65% into atmosphere and 30.02% into soil. This revealed that the nitrogen loss rates were relatively high and the environmental load of nitrogen was huge in the food chain system in Changshu City. Enhancing nitrogen cycle utilization efficiency and decreasing nitrogen inputs in farm-livestock production would be critical to nitrogen control in agricultural system. |
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