黄土高原坡耕地沟蚀土壤质量评价

黄土高原坡耕地沟蚀广泛而严重。科学评价沟蚀土壤质量是侵蚀环境下土壤保育和利用的重要基础。论文以沟间土壤为对照,分析了坡耕地沟蚀对土壤质量单因子的影响并建立了沟蚀土壤质量综合评价模型。利用加权和法对黄土高原坡耕地不同沟蚀深度下土壤质量进行综合评价。结果表明:①沟蚀对坡耕地不同土壤质量因子的影响有较大差异。沟蚀导致土壤硬化,pH值增加,而土壤团聚体和养分含量(除全磷)随着沟蚀深度增加表现出明显的层次性,近似呈"W"型变化规律。②沟蚀深度对土壤质量的影响可以用幂函数y=0.866 8 x ^-0.142(R²=0.877)较好地拟合。微度侵蚀(<5 cm)、中度侵蚀(5~30 cm)和重度侵蚀(30~50 cm)的土壤质量指数较沟间土壤分别降低了10.6%、27.9%和36.5%。沟蚀深度5 cm和30 cm是土壤质量显著下降的两个关键点。③反映沟蚀土壤质量的指标可以归为肥力因子、质地因子和结构因子三类。土壤有机质、水稳性团聚体、土壤比表面积和容重4项指标能够很好地反映土壤质量状况,可作为坡耕地沟蚀土壤质量的表征指标。     

系统论在企业改造工程安全管理上的应用

运用系统论思想分析了企业大中修改造工程的特点,有针对性地提出了经实践检验行之有效、系统化的6项安全管理原则,具有较强的可操作性。     

137Cs示踪红壤丘陵区坡地土壤侵蚀的研究--以江西丰城市为例

通过137Cs示踪技术,并采用相关的土壤侵蚀定量模型,对红壤丘陵区江西丰城市坡面不同土地利用类型、方式以及不同地貌部位的土壤侵蚀进行了研究。结果表明：研究区137Cs的本底值为1 992.45±145.63 Bq/m2;试验区典型坡地不同地貌部位均存在着一定程度的土壤侵蚀,且侵蚀强度总的变化趋势为坡底部>坡中部>坡顶部;不同土地利用类型和方式下的坡面侵蚀强度亦呈现一定的分异现象,从大到小依次为耕作土坡面>退耕30年+退耕1年混合坡面>退耕30年坡面>荒坡。     

基于Matlab的超声空化场测量与可视化分析

为探究超声空化机理、明确超声条件对空化效应的影响,采用铝箔腐蚀法,测量了不同条件下槽式与探头式超声装置中空化场分布,在Matlab平台实现了超声空化场的二维可视化,并通过超声基础试验进行分析验证,.结果表明:槽式超声场分布不均匀,随着超声频率的增加,铝箔腐蚀面积减小,空化效应减弱;空化效应在波腹处最明显,高效区面积最大.探头式超声空化场的高效区主要分布在探头轴线附近,随着铝箔与探头距离的增加,空化效应逐渐减弱,低效区面积增加;空化效应随超声波声能密度的增加而增强,声能密度5W/mL时,腐蚀面积可达80%以上.相同条件下,槽式超声波反应器中超声空化效应较强.超声波声能密度越大,处理后的污泥上清液SCOD越高,破解效果好;随着超声频率的增加,污泥破解程度下降,空化效应减弱.     

雅鲁藏布江源区土壤侵蚀特征

以雅鲁藏布江源区所在的马泉河流域为研究区域,运用遥感和G IS技术对土壤侵蚀及其空间分布的地貌特征进行研究,结果表明:轻度及其以上强度土壤侵蚀面积为18 933.33 km2,占源区面积的71.86%;冻融侵蚀是土壤侵蚀的主要形式,占源区面积的82.53%;风力侵蚀占5.33%,集中分布在河谷宽谷段;水力侵蚀面积所占比例较小,以微度侵蚀为主。土壤侵蚀的地理分布规律受海拔高度的影响较大,垂直分异明显,主要发生在坡度等级较低、地势较平坦的地区。轻度以上冻融侵蚀主要分布在海拔4 600~5 200 m,且有20%以上集中在0°~5°坡地;风力侵蚀主要分布在海拔4 600~5 600 m、0°~25°坡地。极强烈风力侵蚀以西南坡向最大,南、西、东南坡和平地分布较少。强烈风力侵蚀以平地所占比例最大,东北和西2个坡向次之。坡向对冻融侵蚀影响较小。     

四川德昌县凉峰沟泥石流灾害特征及防治对策

论述了四川德昌县凉峰沟泥石流形成条件、触发因素和泥石流灾害特征.对泥石流危险度进行了定量评价,并提出了相应的泥石流防治对策.     

The Role of Soil Surface Crusting in Desertification and Strategies to Reduce Crusting

Soil crusting decreases infiltration, increases erosion, and impedes vegetation establishment, so reducing the impact of crusting is of major importance in combating desertification. Although surface crusting has been the subject of considerable research over the past 50 years or more, the practical management of soil crusts remains a challenge for many dryland communities. Crusting occurs in two steps, an initial aggregate breakdown period that occurs under rainfall and a subsequent hardening phase during drying. Several factors influence crust development, but the single most important one is soil aggregate stability. Strategies to reduce crusting can be based either on protecting the surface from raindrop impact or improving aggregate stability, or a combination of both. However, crust control is labor and/or capital intensive and must be thought out clearly in terms of the benefits to be achieved.     

Soil erosion in developing countries: a socio-economic appraisal

Soil erosion is the single most important environmental degradation problem in the developing world. Despite the plethora of literature that exists on the incidence, causes and impacts of soil erosion, a concrete understanding of this complex problem is lacking. This paper examines the soil erosion problem in developing countries in order to understand the complex inter-relationships between population pressure, poverty and environmental-institutional dynamics. Two recent theoretical developments, namely Boserup's theory on population pressure, poverty and soil erosion and Lopez's theory on environmental and institutional dynamics have been reviewed. The analysis reveals that negative impacts of technical change, inappropriate government policies and poor institutions are largely responsible for the continued soil erosion in developing countries. On the other hand, potential for market-based approaches to mitigate the problem is also low due to the negative externalities involved. A deeper appreciation of institutional and environmental dynamics and policy reforms to strengthen weak institutions may help mitigate the problem.     

Use of Soil and Water Protection Practices Among Farmers in Three Midwest Watersheds

Data were collected from 1011 farmers in three Midwestern watersheds (Ohio, Iowa, and Minnesota) to assess factors that influence the use of conservation production systems at the farm level. The “vested interests” perspective used to guide the investigation was derived from elements of social learning and social exchange theories. Respondents were asked to indicate their frequency of use for 18 agricultural production practices that could be adopted on Midwestern farms at the time of the study. Responses to the 18 items were summed to form a composite variable, termed “conservation production index,” for use as the dependent variable in multivariate analysis. Eleven independent variables were identified from the theory as likely predictors of conservation adoption, including respondents' perceptions about production costs, output and risks, and perceived importance of access to subsidies, technical assistance, and informational/educational programs. Regression analysis was used to assess the performance of the independent variables in explaining variance in the conservation production index. Explained variance in the three regression models ranged from 2% in the Minnesota watershed to 19% in the Ohio watershed. The researchers concluded that the model had limited utility in predicting adoption of conservation production systems within the three study watersheds. Findings are discussed in the context of conservation programs within the three areas.     

复合农林业的由来与兴起

由于人口的增长,人们对粮食、烧柴的需求与日俱增,致使森林面积减少,土壤等自然资源退化,生态环境恶化。对此于20世纪70年代提出了“复合农林业(Agroforestry)”,并发展成一门新兴的学科。它有意识地将多年生木本植物与农作物或家畜结合起来,在为农村提供烧柴、木材、饲料、粮食的同时,又可保持土壤肥力,达到持久农业的目的。它对我国大面积山丘地区自然资源的综合利用与保护有着重要的意义。