黄河流域氮素流失模数研究

Characteristics of Nitrogen Loss Modulus in the Yellow River Basin

氮素流失模数是研究区域氮循环与氮平衡的基本参数,对其进行研究有助于从大区域角度评价我国化肥的利用效率。按多年年径流量均值和多年河水氮浓度均值计算所得的黄河19个主要支流的流域氮素流失模数在0.073～1.665t·km-2·a-1,氮素流失模数的大小与区域人口和农业生产水平存在正相关性;由于存在“流域面积尺度效应”,使按干流数据计算得到的黄河流域的氮素流失模数显著地小于按支流资料计算得到的氮素流失模数;由于干流各站点控制的流域范围具有重叠性以及下游水质对上游水质有继承性,使按干流各站数据计算得到的氮素流失模数数值间差异不大;20世纪90年代以后黄河流域的氮素流失模数大大增加。中游头道拐站以上流域1995年的氮素流失模数比1985年增加4倍以上,下游花园口站以上流域1996年的氮素流失模数比1986年增加2倍以上;黄河流域流失的氮主要是以溶解态形式存在于水相中的氮素,流域氮素流失模数与泥沙径流模数之间无明显关系。以花园口站为控制点计算所得的黄河流域的氮素流失模数小于以大通站为控制点计算所得的长江流域的氮素流失模数。黄河流域的氮肥流失率(指黄河流域流氮素流失总量占流域氮肥总施入量的比例)在90年代后期有快速增加趋势,1998年比1997年增加12%,1999年又比1998年增加18%。我国?

Nitrogen loss modulus is one of the basic parameters in the studyi n g of regional nitrogen cycling and nitrogen balance, and the study of this param eter can help assess the utilizing efficiency of the nitrogen fertilizer from th e perspective of a large area. The nitrogen loss moduli of the 19 principal trib utaries of the Yellow River, calculated from many years' data of their averaged river flux and nitrogen concentration, ranged from 0.073～1.665 t·km-2·a-1, which were obviously positively related to the population and agricultural intensity of the region. The nitrogen loss moduli obtained from the mainstream data were less than those from tributaries' because of the 'area scale effect', and the nitrogen loss moduli at different stations along the mainstream of the Y ellow River varied slightly. On the other hand, the nitrogen loss moduli of the Yellow River Basin increased greatly since 1990s: the 1995's value of Toudaoguai Station in the Mid Reaches was 4 times higher than decade before, meanwhile the value of the Lower Reaches Station Huayuankou doubled from 1986 to 1996. We fou nd that the nitrogen was leached from the Valley primarily in the dissolved form and existed in liquid phase, having little relationship with the sediment erosi on modulus in the Yellow River Basin. The nitrogen loss modulus of the Yellow Ri ver Basin based on Huayuankou Station was less than that of Yangtze River based on Datong Station. The nitrogen fertilizer loss ratio (total nitrogen loss to to tal amount of nitrogen fertilizer applied in the Basin) tended to increase in th e late 1990s in the Yellow River Basin, 12%increasing from 1997 to 1998 and 1 8%increasing from 1998 to 1999. The authors call on that this situation shoul d be attached great importance to our researchers of fertilizer, researchers of environment protection and concerned governmental decision-making departments.