Spatio-temporal variation of net anthropogenic nitrogen inputs in the upper Yangtze River basin from 1990 to 2012

The net anthropogenic nitrogen input(NANI) is an important nutrient source that causes eutrophication in water bodies. Understanding the spatio-temporal variation of NANI is important for regional environment assessment and management.This paper calculated NANI in the upper Yangtze River basin(YRB), upstream of the Three Gorges Dam(TGD), from1990 to 2012, and analyzed its spatio-temporal characteristics. Over the past 23 years of the study, the average annual NANI increased from 3200 kg N km^(-2) to 4931 kg N km^(-2). The major components were fertilizer N application, atmospheric N deposition,and net food and feed N import. In the northwest high mountainous region with a sparse population, the main component was atmospheric N deposition. Fertilizer N application and net food and feed N import were concentrated in the Chengdu Plain because of the high population density and large areas of farmland. This research found that NANI increased with rapid urbanization and increasing population. The Pearson correlation results illustrated that the spatial distributions of NANI and its major components were affected by land cover/use, agricultural GDP and total population. Increasing NANI has been the major cause of the degrading stream water quality over the past 20 years and is becoming a major threat to the water quality of the TGD reservoir.

Spatial-temporal Changes of NDVI and Their Relations with Precipitation and Temperature in Yangtze River Basin from 1981 to 2001

Multitemporal NOAA/AVHRR NDVI 图象和每月的温度和降水数据越过盖住时期的长江盆被获得 1981 鈥 ? 001。当空间分析证明 NDVI 被在学习区域成长的植被类型影响时， NDVI 的空间、时间的模式是一样，并且 NDVI 在整个盆在学习时期期间介绍一个增加的趋势。气候指示物在河盆在植被盖子的变化起一个重要作用。在二指示物，温度在整个盆比降水在 NDVI 价值上有重要效果。在 11 subbasins，然而，不同规则在不同 subbasins 被显示出。