地理科学进展 ›› 2010, Vol. 29 ›› Issue (9): 1081-1086.doi: 10.11820/dlkxjz.2010.09.009

• 土地利用 • 上一篇    下一篇

土地利用方式对流域氮输入输出关系的影响以加州San Joaquin流域为例

韩震1,2, 罗橘辘2, 王中根3, Randy A.Dahlgren2, Minghua Zhang2   

  1. 1. 浙江大学生命科学学学院|杭州310058;
    2. 加州大学戴维斯分校陆地、空气与水资源学院|戴维斯|95616;
    3. 中国科学院地理科学与资源研究所|陆地水循环及地表过程重点实验室|北京100101
  • 收稿日期:2009-10-01 修回日期:2010-01-01 出版日期:2010-09-25 发布日期:2010-09-25
  • 通讯作者: 王中根. E-mail: wangzg@igsnw.ac.cn. E-mail:wangzg@igsnw.ac.cn
  • 作者简介:韩震(1988-)|女|山东青岛人.E-mail: hanzhen.zju@gmail.com.
  • 基金资助:

    国家水体污染控制与治理科技重大专项(2008ZX07010-006-6);温州基金项目((XNK07035)

Impact of Land Use on Input and Export of Nitrogen of Watersheds: A Case Study in San Joaquin Valley, CA

HAN Zhen1,2, LUO Yuzhou2, WANG Zhonggen3, Randy A. Dahlgren2, Minghua ZHANG2   

  1. 1. College of Life Science, Zhejiang University, Hangzhou 310058, China;
    2. Department of Land, Air, Water Resources, University of California, Davis 95616, USA;
    3. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • Received:2009-10-01 Revised:2010-01-01 Online:2010-09-25 Published:2010-09-25

摘要:

土地利用方式影响流域氮输入的空间分布和氮素的迁移输出过程,与非点源污染的防治密切相关。本文利用加州San Joaqnin流域数据,考虑不同土地利用方式的影响,在GIS平台上分析了流域氮输入与输出的关系及其空间分布本文提出了一个新的指标(F=CN/(L/Q))来衡量河流氮输出的变化趋势,该指标综合考虑了田间产流和河道输移两个过程的影响因子,能够描述土地利用类型对流域氮素迁移转化的影响。在实例研究中,通过该指标能够指示出研究区氮素流失的高风险区,为流域土地利用规划和非点源污染防治提供了重要的科学依据。

关键词: San Joaqnin流域, 河流氮输出, 流域氮平衡, 土地利用

Abstract:

Land Use influences the spatial distribution of nitrogen (N) inputs in watersheds and the transportation of N to rivers, and is therefore clowly related to non-point pollution. Here we took San Joaquin Valley, one of the most important agricultural areas in the United States, as an example to analyze the impacts of land use on input and riverine N export in this area. Total N loads were monitored at five mainstream sites and four tributary sites along San Joaquin River. The spatially explicit calculation of N input8 for the nine corresponding watersheds was conducted with GIS (Geographic Information Systems). The inputs were calculated as the sum of inorganic fertilizer, organic manure, atmospheric deposition, natural fixation, and crop fixation. The N in water removal and harvest was subtracted. Results showed that total N inputs ranged from 3607 to 12301 kg km-2 yr-1, among which inorganic fertilizer (42%-65%) and organic manure (26%-48%) were the largest sources. The proportion of N inputs exported through rivers ranged介om 0.1% to 8.87%. A new index:F=CN/(L/Q) was developed to characterize the variability of the fractional N export from the watersheds. CN (Curve Number), an empirical parameter from SWAT (Soil and Water Analysis Tool), was used to represent in-field yield of N in agricultural areas. Larger CN indicates larger potential to produce runoff that flushes N into the receiving river channels. L/Q (L: Rivermile, Q:Streamflow) was used to represent the N transport processes in river channels. Regression analysis showed that there was a strong linear correlation between F and fractional N export. The index F has the advantage in using readily available factors to predit trends of N loads in areas which have similar(limate and landscape. Using the product of F and rate of inorganic fertilization, agricultural fields that have high risk of N pollution were identified. The larger value of IFR.F indicates intensive fertilizer application and high runoff potential. We suggested that management and monitoring practices should be applied intensively in these areas.

Key words: land use, nitrogen budget calculation, riverine N export, San Joaquin Valley