Land-use induced changes in topsoil organic carbon stock of paddy fields using MODIS and TM/ETM analysis: A case study ofWujiang County, China

Topsoil soil organic carbon (SOC) that plays an important role in mitigating atmospheric carbon dioxide (CO_2) buildup is greatly affected by human activities.To evaluate the influence of land-use changes on SOC stocks in paddy soils,a new algorithm was developed by integrating MODIS (moderate resolution imaging spectral-radiometer) and TM/ETM data for timely monitoring the land-use change in Wujiang County.Thereafter,the land-use class-maps derived from MODIS and TM/ETM analyses were further used to est...     

Assessing the impact of urbanization on regional net primary productivity in Jiangyin County, China

Urbanization is one of the most important aspects of global change. The process of urbanization has a significant impact on the terrestrial ecosystem carbon cycle. The Yangtze Delta region has one of the highest rates of urbanization in China. In this study, carried out in Jiangyin County as a representative region within the Yangtze Delta, land use and land cover changes were estimated using Landsat TM and ETM+ imagery. With these satellite data and the BEPS process model (Boreal Ecosystem Productivity Simulator), the impacts of urbanization on regional net primary productivity (NPP) and annual net primary production were assessed for 1991 and 2002. Landsat-based land cover maps in 1991 and 2002 showed that urban development encroached large areas of cropland and forest. Expansion of residential areas and reduction of vegetated areas were the major forms of land transformation in Jiangyin County during this period. Mean NPP of the total area decreased from 818 to 699 gCm(-2)yr(-1) during the period of 1991 to 2002. NPP of cropland was only reduced by 2.7% while forest NPP was reduced by 9.3%. Regional annual primary production decreased from 808 GgC in 1991 to 691 GgC in 2002, a reduction of 14.5%. Land cover changes reduced regional NPP directly, and the increasing intensity and frequency of human-induced disturbance in the urbanized areas could be the main reason for the decrease in forest NPP.     

垦利县耕地利用动态监测研究

对土地利用变化进行监测是全球变化的一项基本内容,基于遥感技术的两个最主要的应用是通过影像分类制作土地覆被图和通过变化监测分析土地覆被变化,从而为土地利用分析提供了有力的工具与手段。论文以山东省垦利县为研究对象,探讨了利用TM数据进行耕地信息提取及监测,包括遥感图像的几何精校正、数据配准、研究区数据提取及图像增强等,分别采用屏幕目视解译法和自动分类与目视解译结合法两种分类方法提取耕地信息,在此基础上对耕地分类结果进行叠加监测,并对分类和监测结果进行了验证;最后对耕地资源的变化做了一个系统的分析。结果表明,在计算机自动分类结果的基础上,进行目视修正,可以有效地提高分类精度,适宜于农用土地区尤其是滨海盐渍土区的耕地信息提取。     

基于Landsat TM/ETM+/OLI遥感大数据分析南京市1984—2015年大气能见度变化趋势

对南京市1984—2015年Landsat 4／5／7／8卫星TM／ETM＋／OLI传感器获取的遥感数据，利用ENVI遥感软件的FLAASH大气校正模块，进行了区域大气能见度（ VIS）遥感反演。结果表明，时间跨度达30余年的Landsat卫星遥感数据影像序列反演的VIS呈明显的下降趋势，20世纪80年代数值较高，“差”能见度（＜10 km）的观测率不到6％，21世纪以来VIS下降明显，“差”能见度的观测率为20％～25％。与2010—2015年南京市PM10、PM2．5监测数据进行了对比，在城市空气清洁及污染较轻时，星地监测结果有较好的一致性，但中到重污染天气时FLAASH算法反演VIS偏高，侧重于代表离主城区距离远的偏远乡野山林地区的能见度状况。     

1,2,4,5-四氯苯 C 18 Empore TM 膜/水分配系数的研究

研究了1，2，4，5-四氯苯在C18膜／水相之间的分配规律。1，2，4，5-四氯苯在：25℃，80r／min条件下恒温震荡96h可达分配平衡，温度和盐度对1，2，4，5-四氯苯C18膜／水的分配过程影响很小，1，2，4，5-四氯苯C18膜／水分配平衡时间受溶液体积和容器容积的影响，但不受溶液中C18膜膜量的影响，推测脂溶性小于或接近1，2，4，5-四氯苯的有机污染物在恒温震荡条件下C18膜与水之间的分配96h可达到平衡。