移动床生物膜反应器充氧能力的试验研究

对移动床生物膜反应器的充氧能力进行了试验研究，结果表明：反应器充氧能力在添加填料比无填料时大；在悬浮载体能够均匀流化的填充率范围内，反应器充氧能力随着填充率的增大而增大；当填充率大于可以均匀流化的最大填充率时，反应器的充氧能力略有下降。     

INTEGRATING SERVICE‐LEARNING INTO WATERSHED MANAGEMENT PROGRAMS: OPPORTUNITIES AND CHALLENGES1

ABSTRACT: The objective of this article is to open a dialogue on integrating service‐learning into community based watershed management programs and to discuss opportunities and challenges that a service‐learning program presents to universities and communities. The article presents the concept and definition of service‐learning, and arguments concerning why institutions of higher education and university faculty and students should be involved with community based watershed management programs. The article describes a case study for developing a service‐learning program for watershed management at Virginia Tech and discusses lessons learned from the case study. The paper concluded that to make a service‐learning program sustainable, there should be a long term plan, regular and effective communication with the stakeholders, and some incentives for faculty and students for long term commitment to the community based watershed management programs.     

SEDIMENT OXYGEN DEMAND IN THE ARROYO COLORADO RIVER1

ABSTRACT: The lower reaches of the Arroyo Colorado have historically failed to meet their use under subsection 303(b) of the U.S. Clean Water Act due to fecal coliform bacteria and low dissolved oxygen (DO). Fish kills, especially at the tidal confluence at the Port of Harlingen, Texas, have been reported. Oxygen demand from sediment (SOD) for a river typically has two states‐diffusion limited SOD (SOD) and potential SOD (pSOD), expressed when sediment is resuspended through increased flow or other disturbances. The objective of this research was to measure SOD in the Arroyo Colorado River in situ, estimate pSOD ex situ, and evaluate the relationship between SOD and the depositional environment. We measured SOD and pSOD in the Arroyo Colorado River at up to eight sites over three sampling events. We identified the sample sites based on a modified Rosgen geomorphic index for streambed stabilization. Sites with high sediment deposition potential had high SOD. The average values of SOD between sites were 0.62 g/m²/day (standard deviation 0.38 g/m²/day) and ranged from 0.13 to 1.2 g/m²/day. Potential SOD values ranged from as low as 19.2 to as high as 2,779 g/m³ sediment/ day. Potential SOD can serve as an indicator of the possible impact of SOD from resuspended sediment in stream systems.     

GROUND WATER NITRATE REDUCTION IN GIANT CANE AND FOREST RIPARIAN BUFFER ZONES1

ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone.     

提高化学需氧量质控合格率的研究

大庆油田化工总厂废水中化学需氧量（COD）的测定采用库仑法。为了提高质控合格率，从人员素质、仪器设备、电级内液等9个方面分析寻找导致误差的主要影响因素并制定对策。同时对影响电极内液及消解的因素进行正交实验确定最佳条件。结果使库仑法质控合格率由90％提高到95％，测定38次标样全部合格。     

螺旋升流反应器氧传递性能的试验研究

本文主要针对螺旋升流反应器技术特性，对工艺的好氧反应器进行了氧传递性能的试验研究，考察了反应器水深、曝气量等对螺旋升流反应器氧转移过程的影响；并对试验数据进行回归，得到了氧传质总系数与螺旋升流反应器内表现气速的数学关系。试验结果表明，螺旋升流反应器具有良好的氧传递特性，是一种新型的高效、节能的污水处理反应技术。     

促进农村居民消费需求扩张的对策分析

通过对影响我国农村居民消费需求不足的原因分析，认为我国农村居民收入水平偏低且增长缓慢是导致需求不足的关键因素。此外商品有效供给不足、农村的消费观念、消费环境和农村居民的文化素质也在一定程度上影响了农村居民的消费需求。     

典型装饰织物在不同氧浓度下热分析研究

人民生活水平的提高使人民对室内环境的舒适程度提出了更高要求 ,室内装饰织物的用量迅速增加 ,室内装饰织物在燃烧时会释放出大量有毒物质和热量 ,对人及环境构成了巨大危害。因此 ,研究装饰织物的燃烧特性非常重要。笔者利用热重 -差热 (TG -DTA)分析仪对纯棉、棉麻和腈纶这几种典型的装饰织物在不同的氧气浓度 (10 % ,15 % ,2 1% )和升温速率 (10K/min ,30K/min)条件下进行了热重分析 (TG)和差热分析 (DTA)实验 ,研究了它们的燃烧特性 ,并着重进行了不同氧浓度下的对比研究 ,发现试样的燃烧分为两个阶段。建立了以一级反应模型为主的动力学方程 ,并得出了各阶段的动力学参数、表观活化能和频率因子。     

入世带来的环境压力及其对策探讨

入世给我国带来了一定的环境压力,主要表现在资源消耗、污染进口和产业冲击三方面.外商投资增长及外国人入境消费可能引起资源过度消耗,环境风险较大的项目和危险废弃物也可能乘机而入.受国外环保产业和环保服务业的冲击,我国相关产业面临严峻挑战.现阶段,我国的法规标准和公众意识是影响入世所带来的环境压力的两个重要因素.缓解环境压力的举措需要遵循两个原则:制度改革和管理改革结合的原则;短期措施和长期战略结合的原则.     

NITROGEN AND ORGANIC MATTER LOSSES IN NO‐TILL CORN CROPPING SYSTEMS1

ABSTRACT: Intensive cropping systems based on mechanical movement of soil have induced land degradation in most agricultural areas due to soil erosion and soil fertility losses. Thus, farmers have been increasing fertilization rates to maintain an economically competitive crop yield. This practice has resulted in water quality degradation and lake eutrophication in many agricultural watersheds. Research was conducted in the Patzcuaro watershed in central Mexico to develop appropriate technology that prevents nonpoint source pollution from fertilizers. Organic matter (OM) and nitrogen (N) losses in runoff and nitrate (NO₃‐N) percolation in Andisols with corn under conventional till (CT) and no‐till (NT) treatments using variable percentages of crop residue as soil cover were investigated for steep‐slope agriculture. USLE type runoff plots were used to collect water runoff, while suction tubes with porous caps at 30, 60, and 90 cm depth were used to sample soil water solutes for NO₃‐N analyses. Results indicated a significant reduction of N and OM losses in runoff as residue cover increased in the NT treatments. Inorganic N in runoff was 25 kg/ha for NT without residue cover (NT‐0) and 6 kg/ha for the NT with 100 percent residue cover (NT‐100). Organic matter losses in runoff were 157 and 24 kg/ha for the NT‐0 and NT‐100 treatments, respectively. Nitrate‐N percolation was evident in CT and NT with 100 percent residue cover (NT‐100). However, NT‐100 had higher NO₃‐N concentration at the root zone, suggesting the possibility of reducing fertilization rates with the use of NT treatments.