| 挠力河融水径流氮分布特征及其对流域LULC的响应 |
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| 引用本文： | 王建华,吕宪国,田景汉.挠力河融水径流氮分布特征及其对流域LULC的响应[J].资源科学,2008,30(8):1129-1134. |
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| 作者姓名： | 王建华 吕宪国 田景汉 |
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| 作者单位： | 中国科学院东北地理与农业生态研究所湿地生态与环境重点实验室，长春 130012;中国科学院东北地理与农业生态研究所湿地生态与环境重点实验室，长春 130012;河北沧州师范专科学校，沧州 061001 |
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| 基金项目： | 中国科学院知识创新工程项目:"三江平原农田生态系统稳定性对湿地垦殖的生态响应"
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中国科学院东北振兴科技行动计划重点项目:"三江平原典型退化湿地恢复技术与示范" |
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| 摘 要： | 春季融水是中国东北地区河流的重要水文特征，然而对其研究却不多见。以东北三江平原挠力河为研究对象，进行春季融水径流氮分布特征的研究，并利用 GIS 技术获取各流域土地利用/土地覆被 (Land Use / Land Cover，LULC) 类型面积百分比。将各流域出口氮浓度值与流域 LULC 类型面积百分比进行Spearman非参数相关分析，结果表明，挠力河中下游融水径流氮分布对流域 LULC 具有重要响应。其中，农田和居民点对径流氮分布具有正效应，林地具有负效应，湿地的正负效应有待进一步研究。并推断，农田和居民点是挠力河中下游融水径流的氮源，林地是氮汇。从理论上分析，湿地在流域中处于相对较低的位置，应该是接收氮的汇，具有吸收、蓄存和转化氮的功能，且湿地的氮吸收存在一个随面积大小不同而变化的阈值；当氮的输入量低于这一阈值时，湿地为氮汇，而当氮的输入量高于这一阈值时，湿地便成为向下游径流输出氮的源。尽管如此，湿地作为水陆之间的过渡带，独特的位置使其成为农田与径流之间的缓冲带，是氮从农田向径流迁移的最后一道屏障。因此，建议以流域为单元进行LULC规划与管理，加强河岸缓冲带保护与建设，恢复和重建河流中下游河岸湿地，构造宽度适宜、结构完整和高度连通的河岸植被缓冲带。
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| 关 键 词： | 挠力河 流域LULC 融水径流 氮分布特征 |
| 修稿时间： | 5/5/2008 12:00:00 AM |
Distribution of Nitrogen in Snowmelt Runoff and Its Response to Watershed LULC: A Case Study of Naoli River, Northeast China |
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| WANG Jian-hu,LU Xian-guo and TIAN Jing-han.Distribution of Nitrogen in Snowmelt Runoff and Its Response to Watershed LULC: A Case Study of Naoli River, Northeast China[J].Resources Science,2008,30(8):1129-1134. |
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| Authors: | WANG Jian-hu LU Xian-guo and TIAN Jing-han |
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| Abstract: | Snowmelt in early spring is one of the main hydrological events in Northeast China, but previous research has been limited. Water samples were collected from 10 sampling sites scattered throughout the middle and lower reaches of the main stream and 2 major tributaries of the Naoli River in late April 2007. These were analyzed to study the distribution of nitrogen in snowmelt runoff of the Naoli River in Sanjiang Plain during the early spring snowmelt period (April-June). In addition, areal percentages of four types of Land Use/Land Cover (LULC) in 10 sub-basins represented by the 10 sampling sites were obtained using GIS techniques. Spearman non-parametric correlativity analysis between nitrogen distribution in the snowmelt runoff and watershed LULC patterns showed a significant response of TN and N fraction concentration in snowmelt runoff to the watershed LULC patterns. Cultivated land had a positive correlation and woodlands had a negative effect on TN and N fraction concentration in snowmelt runoff, but the effect of wetlands need to be further studied. From this, we can infer that farmland or cultivated area is a nitrogen source, and woodlands function as nitrogen sinks for melt runoff in the Naoli River Basin. Theoretically, with the function of absorption, storage and transformation of nitrogen into other forms, wetlands would be nitrogen sinks because of their relatively low positions downstream in the basin. Moreover, whether a wetland functions as a sink or source depends on a threshold value related to the size of the wetland area. If the nitrogen input is lower than this threshold value, wetlands will be nitrogen sinks; if the nitrogen input is higher than the threshold value, wetlands will become sources inputting nitrogen into the runoff of lower reaches. Nevertheless, as a transitional zone between water bodies and high land, wetlands are a buffer zone between farmland and surface runoff, and the last barrier preventing nitrogen flowing from farmland to the river. The results of this study highlight the importance of maintaining vegetated riparian buffer zones for protection of surface water quality, and we suggest a master planning, design and management of LULC patterns at the watershed scale. This should include rehabilitation and reconstruction of riparian wetlands in the middle and lower reaches of the river, and construction of riparian vegetation buffer zones of appropriate width, structural integrity and a high degree of connectivity. |
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| Keywords: | Naoli River Watershed LULC Snowmelt runoff Nitrogen distribution |
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