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101.
阐述了Fenton法、O3氧化法、光化学氧化法、电化学氧化法、湿式氧化法、超临界水氧化法、超声波氧化法等不同高级氧化技术的反应原理及在水处理领域中的研究现状,并探讨了不同高级氧化技术在应用过程中存在的问题及今后的研究方向. 相似文献
102.
农户农业生产环节外包行为影响因素分析———基于内蒙古宁城县玉米种植户调研数据 总被引:1,自引:0,他引:1
农业生产环节外包可有效解决农业生产效率低下及土地撂荒等问题.通过构建二元Logit模型,以内蒙古为例,对影响农户农业生产环节外包行为进行研究分析.结果表明,农户自身特征显著影响农户农业生产环节外包行为,具体表现为:主要从事农业生产的农户性别显著正向影响其外包行为,主要从事农业生产的农户健康状况及户主年龄显著负向影响其外包行为;家庭及生产经营特征显著影响外包行为,具体表现为:土地质量促进农户外包行为,农业劳动力数量、兼业化程度、耕地细碎化程度则抑制农户外包行为,土地规模对外包行为先为促进作用,达到20000m2后,则变为抑制作用;农业生产环境特征对农户外包产生显著影响,如加入农业合作社的农户外包的可能性更大.据此,提出相应地促进农业生产环节外包,进而实现规模经营的对策建议. 相似文献
103.
The purpose of soil monitoring system in Slovakia is better to protect the soils with regard to sustainable land use. The main objective is the observation of soil properties concerning the main threats to soil: soil contamination, salinisation and sodification, decline in soil organic matter (SOM), soil compaction and erosion. Soil monitoring system in Slovakia is consistently running since 1993. Its importance consists of providing the information on changing spatial and temporal variations of soil parameters as well as the evolution of soil quality in topsoil and subsoil. Soil monitoring network in Slovakia is constructed using ecological principles, taking into account all main soil types and subtypes, SOM, climatic regions, emission regions, polluted and non-polluted regions as well as various land use. The results of soil monitoring of 318 sites on agricultural land in Slovakia have been presented. Soil properties are evaluated according to the main threats to soil relating to European Commission recommendation for European soil monitoring performance as follows: soil contamination, soil salinization and sodification, decline in SOM, soil compaction and erosion. The most significant change has been determined in physical properties of soils. The physical degradation was especially manifested in compacted and the eroded soils. About 50% of agricultural land is potentially affected by soil erosion in Slovakia. In addition, decline in SOM and available nutrients indicate the serious facts on evaluation and extension of soil degradation processes during the last period in Slovakia. Obtained measured data and required outputs are reported to Joint Research Centre (JRC) in lspra (Italy) and European Environmental Agency (EEA) in Copenhagen (Denmark). Finally, soil monitoring system thus becomes a basic tool for protection of soils and sustainable land use as well as for the creation of legislatives not only in Slovakia, but in EU, too. 相似文献
104.
Heinrich zu Dohna Dannele E. Peck Bruce K. Johnson Aaron Reeves Brant A. Schumaker 《Preventive veterinary medicine》2014
Disease transmission between wild ungulates and domestic livestock is an important and challenging animal health issue. The potential for disease transmission between wildlife and livestock is notoriously difficult to estimate. The first step for estimating the potential for between-species disease transmission is to quantify proximity between individuals of different species in space and time. This study estimates second-order statistics of spatio-temporal location data from radio-collared free-ranging deer, elk and cattle in northeast Oregon. Our results indicate, that when observed simultaneously, elk and cattle occur in closer proximity to each other than what would be expected based on general space use of these species. The same is true for deer and elk but not for deer and cattle. Our analysis also demonstrates that average distances between cattle and elk are largely driven by rare events of close co-mingling between the species, which extend over several hours. Behavioral causes for these co-mingling events are currently unknown. Understanding the causes for such events will be important for designing grazing practices that minimize wildlife–livestock contacts. 相似文献
105.
106.
Laboratory design to simulate complexity of forest floor for studying the role of fauna in the soil processes 总被引:2,自引:0,他引:2
Summary We developed a technique for simulating the complexity of the soil system under controlled laboratory conditions. Removable microcosms were inserted in a homogeneous substrate soil in a large plastic box. This macrocosm was sealed, except for an inlet and outlet for air flow, and an aperture for collecting leachates. The system can be designed and manipulated in various ways according to the needs of a particular experiment. Respiration and nutrient fluxes can be measured either from the whole macrocosm or separately from the microcosms. We have performed three experiments in order to evaluate the role of animals in the soil processes. A set of macrocosms was constructed from components of coniferous forest soil. These were partially sterilized by freezing and then thawing, and re-inoculated with (1) microbes alone, or (2) microbes and fauna. The animal populations became well established, average densities per area approaching those in natural forest soils. However, there were considerable differences in community structure between the experiments. The sterilization did not eliminate microfauna; nematodes reproduced to high densities in the control macrocosms. 相似文献
107.
黄土道路侵蚀过程模拟试验研究 总被引:2,自引:0,他引:2
黄土地区土质道路侵蚀强烈,严重影响当地的生产与交通事业。开展黄土道路侵蚀研究,对于黄土地区水土保持与生态经济建设具有重要意义。采用模拟降雨试验方法研究了黄土道路侵蚀过程,取得了如下结果。(1)道路径流侵蚀发生时间随雨强及坡度的变化皆可用幂函数方程描述;(2)道路径流侵蚀开始时含沙量很高,但很快下降并随降雨历时的延长而逐渐趋于相对稳定;(3)道路侵蚀率变化过程可分为3个阶段:径流侵蚀开始至20min及40min至侵蚀过程结束,侵蚀率随降雨过程的变化较大,20~40min之间基本稳定;(4)道路侵蚀模数随雨强及坡度的变化均可用幂函数方程描述,雨强及坡度对道路侵蚀的综合影响可用二元线性方程描述。 相似文献
108.
109.
Bernhard?WestrichEmail author Ulrich?F?rstnerEmail author 《Journal of Soils and Sediments》2005,5(4):197-200
- DOI: http://dx.doi.org/10.1065/jss2005.11.002
Background and Scope. Apart from their function as indicator or memory for local pollutant inputs, sediments, and especially
sediment cores, can be used as a tool for assessing emissionimmission relationships of contaminants on a river-basin scale.
Methods. In the framework of the SEDYMO program, source effects, i.e. intensity of sediment erosion under different shear
stress, were investigated using a combination of core profile or sampling box studies in laboratory flumes and a mobile in-situ
testing device for sediment stability.
Results. Calculations of immission risks on downstream areas, e.g., from a three-step approach (substances of concern, areas
of concern, areas of risk; Heise et al. 2004), may be directly confirmed from sediment core data, specifically from flood
layers, at the target site. 相似文献
110.
为研究青藏高原高寒湿地旱化对碳通量的影响,探讨高寒湿地旱化碳通量变化规律,本研究于7-8月生长高峰期以高寒湿地、沼泽化草甸和高寒草甸为研究对象,利用TARGAS-1静态箱法,比较高寒湿地不同退化阶段碳交换的动态差异。结果表明:与高寒湿地相比,沼泽化草甸与高寒草甸植被群落光合速率、生态系统呼吸速率、净生态系统碳交换显著提高(P<0.05);不同退化阶段土壤温湿度及植被群落生物量存在显著差异(P<0.05),土壤电导率差异不显著;相比于土壤湿度和土壤电导率,土壤温度对CO2交换的影响更大,其与净生态系统碳交换呈显著负相关(P<0.05),高寒草甸的碳交换对土壤温度的敏感性要大于高寒湿地和沼泽化草甸的碳交换对土壤温度的敏感性;在植物生长高峰期,高寒湿地旱化过程土壤温度显著上升,土壤湿度和植物群落生物量显著下降,导致其碳汇功能呈下降趋势。 相似文献