人类干扰对土壤侵蚀及土壤质量的影响——以苏南宜兴低山丘陵区为例   总被引：11，自引：6，他引：11  

张燕  彭补拙  高翔  唐翔宇  杨浩 《地理科学》2002,22(3):336-341

以苏南低山丘陵区茶园土壤侵蚀与土壤质量改变为研究对象，并取自然状态的杂木林为参照，用^137Cs法估算土壤侵蚀速率；以土壤粗化度、土壤有机质含量及土壤含水量描述土壤质量；在绝对数值的基础上，用变化量探讨研究对象的变化方向与幅度。对比耕作土与非耕作土的土壤侵蚀与土壤质量改变及将它们结合起来研究表明，人类活动有可能加剧土壤侵蚀，加快土壤质地粗化；合理的农业措施虽可减缓土壤质量下降，但防治侵蚀方可治本。  相似文献   

Simulation of regional temperature change effect of land cover change in agroforestry ecotone of Nenjiang River Basin in China     

Liu  Tingxiang  Zhang  Shuwen  Yu  Lingxue  Bu  Kun  Yang  Jiuchun  Chang  Liping 《Theoretical and Applied Climatology》2017,130(3-4):971-978

Currently, US forests constitute a large carbon sink, comprising about 9 % of the global terrestrial carbon sink. Wildfire is the most significant disturbance influencing carbon dynamics in US forests. Our objective is to estimate impacts of climate change, CO₂ concentration, and nitrogen deposition on the future net biome productivity (NBP) of US forests until the end of twenty-first century under a range of disturbance conditions. We designate three forest disturbance scenarios under one future climate scenario to evaluate factor impacts for the future period (2011–2100): (1) no wildfires occur but forests continue to age (S_aging), (2) no wildfires occur and forest ages are fixed in 2010 (S_{fixed_nodis}), and (3) wildfires occur according to a historical pattern, consequently changing forest age (S_{dis_age_change}). Results indicate that US forests remain a large carbon sink in the late twenty-first century under the S_{fixed_nodis} scenario; however, they become a carbon source under the S_aging and S_{dis_age_change} scenarios. During the period of 2011 to 2100, climate is projected to have a small direct effect on NBP, while atmospheric CO₂ concentration and nitrogen deposition have large positive effects on NBP regardless of the future climate and disturbance scenarios. Meanwhile, responses to past disturbances under the S_{fixed_nodis} scenario increase NBP regardless of the future climate scenarios. Although disturbance effects on NBP under the S_aging and S_{dis_age_change} scenarios decrease with time, both scenarios experience an increase in NBP prior to the 2050s and then a decrease in NBP until the end of the twenty-first century. This study indicates that there is potential to increase or at least maintain the carbon sink of conterminous US forests at the current level if future wildfires are reduced and age structures are maintained at a productive mix. The effects of CO₂ on the future carbon sink may overwhelm effects of other factors at the end of the twenty-first century. Although our model in conjunction with multiple disturbance scenarios may not reflect the true conditions of future forests, it provides a range of potential conditions as well as a useful guide to both current and future forest carbon management.  相似文献   

2014—2016年拉萨市大气环境质量分析及评价     

白永飞  吕学斌  平措  张成  布多 《气象科技》2018,46(6):1274-1279

本文对2014—2016年拉萨市6种空气污染物SO2、NO2、PM10、PM25、CO、O3的浓度变化进行了分析和评估。结果表明：①拉萨市区大气污染物以PM10为主,其次是O3;②拉萨市区大气环境中SO2、CO的含量逐年下降,但是,NO2含量逐年上升;③拉萨市大气环境中的PM25与PM10比值明显偏低,表明拉萨市大气环境质量主要的影响因素为自然因素。  相似文献   

Progress in Study of Potash Resources of Oil (Gas) Field Brine in China     

Mu Yanzong  Nie Zhen  Bu Lingzhong  Wang Yunsheng  Wu Qian 《地球科学进展》2016,31(2):147-160

With a population of 1.3 billion, China is a large agricultural country. However, China is short of potash resources as the external dependence is more than 50% for many years. With the limited possibility for increasing potash reserves from surface salt lakes, and the challenge of finding potash deposit from marine strata has not been yet overcome, the oil (gas) field brine resources has become the preferred source for the urgent needs of potash. In recent years, a lot of exploration and research work on the oil (gas) field brine has been done under the guide of “oil and potash co-exploration” policy and delightful achievements have been obtained. The research achievements at Qaidam Basin, Sichuan Basin, Jianghan Basin and Tarim Basin were summarized in the present paper. All of the above basins are the most important areas with great prospects of oil (gas) field brine. This paper mainly focused on three aspects, the brine characteristics, the brine geochemistry and resource assessment. After the summary, the characteristics of oil (gas) field brine and the progress in study of that were gotten in different basins. It was suggested that the research work of (gas) field brine at Qaidam Basin should be emphasized. It was concluded that the evaluation work of oil (gas) field brine resources is insufficient at the four basins, and it is urgent to establish oil (gas) field brine resources evaluation criteria and methods.  相似文献   

冲抓锥设计选型中的几个理论问题          下载免费PDF全文

卜长根 《探矿工程》1995,(3):40-43

分析了冲抓锥的性能参数（锥重、容重比、提升负荷和结构尺寸）对冲抓锥闭合特性的影响，从冲抓锥闭合过程的传力特性和岩土阻力特性两方面，提出了改善冲抓锥闭合特性的措施。  相似文献   

Removal of bisphenol A (BPA) from biologically treated wastewater by microfiltration and nanofiltration     

M. Zielińska  K. Bułkowska  A. Cydzik-Kwiatkowska  K. Bernat  I. Wojnowska-Baryła 《International Journal of Environmental Science and Technology》2016,13(9):2239-2248

Bisphenol A (BPA) is an endocrine disruptor that is difficult to completely remove from wastewater by conventional biological methods. Increased post-treatment BPA removal with ceramic membranes is worth investigating because of these membranes’ mechanical and chemical stability and lifespan. To determine the effectiveness of ceramic membranes for post-treatment of biologically treated BPA-contaminated wastewater, microfiltration (MF) and nanofiltration (NF) were conducted. Both processes removed BPA completely at an initial BPA concentration of 0.3 ± 0.14 mg/L. Increased concentration of 0.7 ± 0.29 mg/L decreased BPA removal. MF removed at least 24 % of BPA, presumably because BPA was adsorbed on particulate matter, which was retained by the membrane, or adsorbed on its surface. NF removed up to thrice more BPA. MF and NF completely removed suspended solids and 40–60 % COD. Filtration capacity decreased with time due to fouling but did not depend on initial BPA concentration. BPA concentrations in municipal wastewater are typically lower than the lowest concentration tested, where MF completely removed BPA. Hence, MF ceramic membranes appear a promising solution for post-treatment of BPA-containing wastewater. MF can be used at a much lower transmembrane pressure than NF, requiring less energy to pump wastewater through the membrane, thus reducing costs.  相似文献   

长治市2003年8月26日暴雨过程分析          下载免费PDF全文

王正旺  白根俊  庞转棠  魏建军  卜祥朔 《山西气象》2004,(3):3-4,34

本文运用天气形势，物理量场，单站总温度对2003年8月26日长治市区域性大暴雨进行了综合分析，找出了此次暴雨天气产生的环流背景，影响系统，物理量场在暴雨中的特征以及单站总温度在暴雨中的变化规律。  相似文献   

长治市气象台报务转发系统          下载免费PDF全文

杨建民  王宗仁  卜祥朔  孙英杰 《山西气象》2004,(3):25-26

在地市气象台向省气象台转发气象报文时，由于县局与市局报路时有不畅，且常有停电现象，使得传统的方法很烦琐，不符合时代发展的要求。为此．我们开发了《长治市气象台报务转发系统》。目前该系统已开发完成，本文主要介绍该系统的开发和主要功能。  相似文献   

Bericht über die Arbeiten ichthyologischer und fischereilicher Art,die für die 13. Arbeitssitzung der Internationalen Arbeitsgemeinschaft Donauforschung vorgelegt wurden     

Prof. Dr. Th. Buşniţa 《Aquatic Sciences - Research Across Boundaries》1971,33(1):322-333

Ohne Zusammenfassung  相似文献   

杭州市滑坡地质灾害危险性区划与评价     

俞布  潘文卓  宋健  缪启龙  张玮玮  段春锋 《岩土力学》2012,33(Z1):193-199

基于证据权法构建滑坡地质灾害评价模型,进行杭州市滑坡地质灾害危险性区划研究。主要数据源包括1930－2009年杭州市域采集到的1 905个地质灾害个例以及杭州市地质图、土地利用数据及数字高程模型（DEM）等。利用Arcgis空间分析及信息提取功能,筛选强降水、地层岩性、坡度、坡向、坡高、河网与道路缓冲等证据因子,并运用证据权法客观确定各因子权重, 最后通过Arc-WofE扩展模块对多种优选因子的叠加,计算任意格网单元的滑坡发生概率,实现对潜在滑坡点位的空间预测。经分离样本法验证,区划准确率为88.3%,分析结果与现有滑坡的分布情况比较吻合。据此表明证据权法在多指标评价及其权重确定等方面具有普适性,值得在滑坡地质灾害危险性区划等方面推广应用。  相似文献