%0 Journal Article
%T Distribution of Nitrogen in Snowmelt Runoff and Its Response to Watershed LULC: A Case Study of Naoli River, Northeast China<br>挠力河融水径流氮分布特征及其对流域LULC的响应
%A WANG Jian-hu
%A LU Xian-guo
%A TIAN Jing-han
%A <br>王建华
%A 吕宪国
%A 田景汉
%J 资源科学
%D 2008
%I 
%X 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.
%K Naoli River
%K Watershed LULC
%K Snowmelt runoff
%K Nitrogen distribution<br>挠力河
%K 流域LULC
%K 融水径流
%K 氮分布特征
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=B5EDD921F3D863E289B22F36E70174A7007B5F5E43D63598017D41BB67247657&cid=B47B31F6349F979B&jid=9DEEAF23637E6E9539AD99BE6ABAB2B3&aid=DBD823771AC7665850B187FAEC40DDB0&yid=67289AFF6305E306&vid=340AC2BF8E7AB4FD&iid=5D311CA918CA9A03&sid=2C195A225F9C61A0&eid=9F83C44826B8A7D6&journal_id=1007-7588&journal_name=资源科学&referenced_num=0&reference_num=25