Evaluating and Managing Cumulative Effects: Process and Constraints

Since any proposed activity could contribute to a wide range of potential CEs at different spatial and temporal scales, a tiered or nested approach should be followed to assess CEs. The difficulty of assessing and predicting CEs also suggests that in many cases the most efficient approach is to focus on minimizing on-site impacts. Under some circumstances adaptive management can also be a viable alternative to detailed CE assessments. Regular monitoring and feedback is critical to the successful management and regulation of CEs.     

平原区交叉口安全分析与改善对策研究

针对目前平原区公路交叉口事故多发的现状,笔者对平原区公路交叉口与山区公路交叉口进行对比,指出平原区公路交叉口具有数量多、范围大、车速高的特点;同时分析平原区公路事故情况,指出平原区公路交叉口事故多发的主要致因是缺乏渠化、路权不清,车速过高和视距不足;提出了交叉口安全保障的一般措施,并具体介绍了明确路权、降低车辆行驶速度和增加交叉口行车视距的方法。除介绍了平原区公路交叉口的一般处置措施外,笔者还将平原区公路交叉口分为大型交叉口、村镇交叉口和小型交叉口,并针对不同类型的交叉口的特点,从标志、标线、减速丘、薄层铺装、宣传教育等方面提出了相应的安全保障措施。     

浅谈项目经理对工程施工的安全控制

安全贯穿整个施工过程中,没有安全就没有施工质量.通过施工实践,阐述项目经理对工程施工的安全控制.     

芜湖市生态农业系统设计

通过对生态农业内涵与模式的认识，指出中国生态农业的研究侧重于对生态脆弱区与具体模式的提炼，而对经济发达区、城郊区缺乏研究，对社会经济条件关注较少。针对芜湖市自然条件、社会经济条件和生态环境现状等地域基础的分析，分别从产品、产业、地域三个方面进行了生态农业系统设计，从而力图把握生态农业的系统本质，将生态建设、经济建设以及各种支撑体系建设进行综合考虑，充分发挥生态农业思想在区域发展中的作用。     

Livestock excreta management through vermicomposting using an epigeic earthworm Eisenia foetida

In India, millions of tones of livestock excreta are produced. Our study explores the potential of an epigeic earthworm Eisenia foetida to compost different livestock excreta (cow, buffalo, horse, donkey, sheep, goat and camel) into value added product (vermicompost) at the laboratory scale. Vermicomposting resulted in lowering of pH, electrical conductivity, potassium and C:N ratio and increase in nitrogen and phosphorus contents. Total K was lower in the final cast than in the initial feed. C:N ratios of the vermicomposts ranged from 16.2 ± 2.17 to 75.4 ± 6.84. Microbial activity measured as dehydrogenase activity in buffalo, donkey and camel wastes increased with time up to day 90. But in sheep and goat wastes, maximum dehydrogenase activity was recorded on day 60 and decreased thereafter. The cocoons and hatchlings production by Eisenia foetida in different excreta were also investigated. The greatest number and biomass of hatchlings was recorded in horse excreta followed by cow, goat and sheep excreta. Thus, cow, horse, sheep and goat excreta show potential as good substrates in vermicomposting using Eisenia foetida, although further research is required to explore the feasibility of use of buffalo, donkey and camel excreta in combination with cow/sheep/goat excreta.     

REAL-TIME SOIL WATER MONITORING FOR OPTIMUM WATER MANAGEMENT1

Abstract: Efficient water resource management is one of the most important policy issues facing agriculture in Hawaii in the years ahead. Soil water sensors, multisensor capacitance probes (MCP), have been successfully used for different water management projects. These MCPs monitor water content at multiple depths and at various locations in real-time. The objectives of this study were to determine the effect of water content on field soil bulk density of Wahiawa silty clay tropical soil; measure field saturated hydraulic conductivity of this tropical soil: calibrate MCP system for this soil: and monitor and evaluate real-time soil water content variations under a tomato crop using the calibrated MCP system. Sensor calibration was conducted under laboratory conditions. Soil bulk density at different water contents and saturated hydraulic conductivity were measured on the field. Bulk density increased with increasing water content: there was a 30 percent bulk density increase as a result of 0.25 cm³ cm^-3 water content variation. Compared with the manufacturer's calibration, site specific laboratory calibration of MCP gave a more accurate determination of soil water. Field determined saturated hydraulic conductivity was higher than laboratory determined values reported in the literature for the same soil type. Real-time soil water content monitoring within the root zone showed substantial variations due to water input (irrigation and rainfall) and water output (evapotranspiration and deep percolations). However, water content variations were much further reduced in the soil layer below the root zone.     

DOCUMENTATION OF HIGH SUMMER FLOWS ON THE POTOMAC RIVER FROM THE WOOD ANATOMY OF ASH TREES1

ABSTRACT: Ash trees (Fraxinus americana L. and F. Pennsylvanica Marsh.) collected from the flood plain of the Potomac River near Washington, D.C., were studied for evidence of associations between known periods of above-average summer flows and changes in wood-growth anatomy. Concentric bands of latewood fibers with atypically large lumens and thin walls commonly developed in trees growing near the low-water channel. Discharge records indicate that roots of most trees with these “white rings” were flooded temporarily during the latewood-growth interval. Trees apparently were not damaged and a concomitant reduction of internal water stresses seems to have accelerated the rate of radial growth. The intra-ring position of anomalous fibers generally corresponded to the time of increased discharge within the estimated interval of latewood growth. Anomalous fibers occasionally formed in unflooded trees, but their position also coincided with episodes of increased discharge. The results of these studies may have applications for streamflow-reconstruction techniques where hydrologic data are incomplete or lacking.     

西部大开发中“西气东输”的储量保证与可持续发展

在西部大开发中 ,能源占有举足轻重的作用。我国西部的塔里木、准噶尔、吐 -哈、柴达木、鄂尔多斯、四川等六大含油气盆地含有丰富的天然气资源 ,储量大于 5 0 0× 10 8m3的 9个大气田中 ,西部就占 7个。中国天然气预测资源总量为 38× 10 12 m3,其中西部天然气预测资源量为 2 2 .4× 10 12 m3,占天然气预测资源总量的 5 8.9%。仅就西部的塔里木盆地而言 ,剩余可采储量为 3397× 10 8m3,按年产 12 0× 10 8m3计算 ,储采比为 2 8,塔里木盆地天然气有动态稳产 30年的储量保证 ,这对于“西气东输”工程的实施、西部经济的腾飞和可持续发展具有重要意义     

A model of radiocesium cycling in a sand hills—Turkey Oak (Quercus laevis) ecosystem

Digital simulation models of radiocesium cycling in Turkey Oaks were developed from in situ ¹³⁴Cs tagging studies. Predictions of ¹³⁴Cs steady-state distribution for 3-, 4- and 5-compartment, donor-controlled models were compared with the estimated fallout ¹³⁷Cs distribution as a measure of model validation; output from the 5-compartment model compared best. Sensitivity analysis demonstrated that Turkey Oak burden of ¹³⁴Cs was equally sensitive to the output rate from the tree compartment and the availability of ¹³⁴Cs for uptake (i.e., presence in the root zone) but not the rate of uptake by Turkey Oaks. Observed distribution and model predictions indicate that radiocesium is readily bioaccumulated by Turkey Oaks (～13% of the ecosystem burden) from the soil and is cycled within the sand hills—Turkey Oak ecosystem.     

Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics,Part I: Corn Distillers’ Dry Grain

Distillers dry grain (DDG) was derivatized either by carboxymethylation, glutaration, maleiation, phthallation, or succination in order to produce anionic materials suitable for complexation with soy protein isolate. Infrared spectroscopy confirmed that derivatization of DDG by all reagents was successful. Blending of derivatized anionic products with soy protein resulted in instant precipitation of gels. The gels were centrifuged, molded, and dried into solid pellets with tensile strengths as high as 1.67MPa, suggesting that these materials could be promising as biodegradable structural materials. Infrared spectroscopy suggested the possibility of complexes forming between soy protein isolate and each of the derivatized DDG samples.