Spectral reflectance properties of major objects in desert oasis: a case study of the Weigan–Kuqa river delta oasis in Xinjiang, China

Aiming at the remote sensing application has been increasingly relying on ground object spectral characteristics. In order to further research the spectral reflectance characteristics in arid area, this study was performed in the typical delta oasis of Weigan and Kuqa rivers located north of Tarim Basin. Data were collected from geo-targets at multiple sites in various field conditions. The spectra data were collected for different soil types including saline-alkaline soil, silt sandy soil, cotton field, and others; vegetations of Alhagi sparsifolia, Phragmites australis, Tamarix, Halostachys caspica, etc., and water bodies. Next, the data were processed to remove high-frequency noise, and the spectral curves were smoothed with the moving average method. The derivative spectrum was generated after eliminating environmental background noise so that to distinguish the original overlap spectra. After continuum removal of the undesirable absorbance, the spectrum curves were able to highlight features for both optical absorbance and reflectance. The spectrum information of each ground object is essential for fully utilizing the multispectrum data generated by remote sensing, which will need a representative spectral library. In this study using ENVI 4.5 software, a preliminary spectral library of surface features was constructed using the data surveyed in the study area. This library can support remote sensing activities such as feature investigation, vegetation classification, and environmental monitoring in the delta oasis region. Future plan will focus on sharing and standardizing the criteria of professional spectral library and to expand and promote the utilization of the spectral databases.     

土壤盐渍化及其治理措施研究综述

土地是人类赖以生存及其一切社会活动的基本条件。土壤盐渍化是当今世界上土地荒漠化和土地退化的主要类型之一,也是世界性的资源问题和生态问题。土地盐渍化对地区的农业生产和生态环境造成很大影响。因此,较准确的分析土壤盐渍化的空间变异特征及变异尺度,揭示其分布规律来防治区域土壤盐渍化具有重要意义。本文首先提出了盐渍化的相关概念,然后对导致土壤盐渍化的主要因素及其土壤盐渍化的研究目标、研究方法进行全面阐述。结论表明土壤盐渍化的时空变化及其与导致这种变化的驱动力之间的因果反馈关系足够有效地揭示人为和自然因素与土壤盐渍化之间相互作用的内在机制,而且可以此来预测其未来发展趋势。最后在此基础上,提出了防治土壤盐渍化的综合性建议以及土壤盐渍化研究中急待解决的研究课题及其有效的研究手段,从而为进一步拓展和深化土壤盐渍化研究的内容及水平打下了牢固基础。     

新疆拖拉机污染物排放时间序列及其影响因素

基于燃油消耗建立了新疆1993~2017年农田作业拖拉机PM₁₀,PM_2.5,HC,NO_x和CO排放时间序列清单,并分析了其演变趋势.从经济发展水平,拖拉机自身的影响和科学技术3个维度出发构建了以柴油机为主要动力的拖拉机污染物排放影响因素清单,并基于粗糙集理论定量分析了污染物排放影响因素.结果表明：1993~2017年新疆拖拉机污染物排放总量处于上升趋势,25a增长了2.0527倍,年均增长率3.67%,单位功率排放量下降了40.03%.农业机械排放标准的提高对污染物排放治理的作用明显.对污染物排放影响因素的定量分析结果显示,总动力、拖拉机数量、机耕面积、机播面积、机收面积、农业机械购置投入、农户固定资产投入和单位功率排放量对污染物排放的影响程度分别为0.2591,0.2491,0.0841,0.0759,0.0934,0.0568,0.0701,0.0701.经济发展水平、拖拉机自身的影响和科学技术对拖拉机污染物影响程度分别为：0.6350,0.2530和0.1119.建立的排放清单和变化趋势较好的反映新疆农业机械污染物排放现状,所得出的结果较好的反映了新疆社会经济,农业机械化和科技水平对拖拉机污染物排放的影响程度.