透视我国环境与资源法制建设

我国自改革开放以来在构建环境与资源保护法律体系方面取得了可喜的成绩,但也存在一些问题。主要表现为:可持续发展战略尚未成为我国环境与资源保护立法的指导思想,我国的环境与资源立法不能完全适应社会主义市场经济的要求和社会发展的需要,我国关于环境与资源的法律法规之间不相统一。造成上述问题的原因有外部因素和内部因素,同时我国的具体国情又使它们更具特殊性。为了有效地解决这些问题,我国须在加强环境立法、健全现有制度、协调内部功能等方面进行不懈的努力。     

Modeling the Influence of Dynamic Zoning of Forest Harvesting on Ecological Succession in a Northern Hardwoods Landscape

Dynamic zoning (systematic alteration in the spatial and temporal allocation of even-aged forest management practices) has been proposed as a means to change the spatial pattern of timber harvest across a landscape to maximize forest interior habitat while holding timber harvest levels constant. Simulation studies have established that dynamic zoning strategies produce larger tracts of interior, closed canopy forest, thus increasing the value of these landscapes for interior-dependent wildlife. We used the simulation model LANDIS to examine how the implementation of a dynamic zoning strategy would change trajectories of ecological succession in the Great Divide Ranger District of the Chequamegon–Nicolet National Forest in northern Wisconsin over 500 years. The components of dynamic zoning strategies (number of zones in a scenario and the length of the hiatus between successive entries into zones) and their interaction had highly significant impacts on patterns of forest succession. Dynamic zoning scenarios with more zones and shorter hiatus lengths increased the average amount of the forest dominated by early successional aspen (Populus sp.). Dynamic zoning scenarios with two zones produced more late successional mature northern hardwoods than scenarios with four zones. Dynamic zoning scenarios with very short (30 years) or very long (120 years) hiatus lengths resulted in more late successional mature northern hardwoods than scenarios with intermediate hiatus lengths (60 and 90 years). However, none of the dynamic scenarios produced as much late successional mature northern hardwoods as the static alternative. Furthermore, the amounts of all habitat types in all dynamic zoning scenarios fluctuated greatly in time and space relative to static alternatives, which could negatively impact wildlife species that require a stable amount of habitat above some minimum critical threshold. Indeed, implementing dynamic zoning scenarios of different designs would have both positive and negative effects on wildlife species and for other objectives of forest management.     

静电除尘器的新应用及其发展方向

静电除尘器广泛应用于冶炼、水泥和电站锅炉等工业领域。在简单介绍传统静电除尘器的分类及结构的同时，列举了目前使用的一些新型的静电除尘器，对静电除尘器在除去气体污染物、异味等方面的新应用进行了概述，并对于使用电凝并、无电晕式等除尘新机理也作了原理性的介绍。     

中压加氢裂化装置危险和可操作性研究

针对中压加氢裂化生产过程存在很大的火灾、爆炸、毒害等危险性的特点，以加氢裂化反应器出口至冷高压分离器进口之间管线为分析节点，对工艺参数流量可能发生的各种偏差进行了危险和可操作性研究，找出了偏差发生的原因及可能导致的后果，提出了相应的控制措施，对提高装置的安全可靠性，预防和减少事故发生具有重要作用。     

汇源大厦托换工程沉降监测分析

汇源大厦托换工程影响巨大，其由立柱拆除引起的沉降监测属高精度要求的大型建筑物变形测量，是托换工程实施的重要保障，结合对托换梁、柱的结构受力分析，分3层布设监测点、依工程进展状况制定合理的观测周期，并采取重点监测与验证相结合的原则，使用精密水准仪配加游标卡尺的特制标卡尺的的特制标尺，多台仪器同时观测等方法，及时反馈了梁柱变形动态，指导拆除及托换进程，保证了工程的顺利进行。     

Pollution characteristics of the recent sediments in the Hangzhou section of the Grand Canal, China

Spatial distribution of heavy metals, arsenic and organic matter in recent sediments in the Hangzhou section of the Grand Canal and their relationships were analyzed. The results showed that the concentrations of heavy metals and organic matters varied widely along the canal, and the average geological accumulation factors decreased in the following orders: organic carbon(2.6), zinc(2.1 ), cadmium(2.0), copper( 1.5), lead(1.1), nitrogen(0.9), mercury (0.8), phosphorus(0.4), arsenic(0.2) and chromium(0). Content of heavy metals and organic carbon in the top 10 cm layer were lower than that of lower layers, except for mercury and organic carbon in the S9 section. Contents of organic carbon in the top 50 cm layer of the mud sediments are significantly higher than those undemeath. In the bottom mud layer, there is a concentration peak of the pollutants. In the mud sediments of the canal, cadmium mainly occurred in the Fe and Mn oxide fraction, copper in the organic fraction, lead in the Fe and Mn oxide fraction, and zinc in the carbonate and the Fe and Mn oxide fraction.     

Characterization of fine organic particulate matter from Chinese cooking

PM2.5 samples were collected by a three-stage cascade impactor at two kinds of Chinese restaurants to characterize fine organic particulate matter from Chinese cooking sources. Major individual organic compounds have been quantified by GC/MS, including series of alkanes, n-alkanoic acids, n-alkanals, alkan-2-0nes and PAHs.Alkanes and ketones make up a significant fraction of particle-phase organic compounds, ranging from C11 to C26,and (C9 to C19, respectively. In addition, other organic compound classes have been identified, such as alkanols,esters, furans, lactones, amides, and nitriles. The mass concentrations of fine particles, alkanes, n-alkanoic acids and PAHs in air emitted from the Uigur style cooking are hundreds times higher than ambient PM2.5in Beijing.     

Preparation and emission characteristics of ethanol-diesel fuel blends

The preparation of ethanol-diesel fuel blends and their emission characteristics were investigated. Results showed the absolute ethanol can dissolve in diesel fuel at an arbitrary ratio and a small quantity of water(0.2% ) addition can lead to the phase separation of blends. An organic additive was synthesized and it can develop the ability of resistance to water and maintain the stability of ethanol-diesel-trace amounts of water system. The emission characteristics of 10%, 20%, and 30% ethanol-diesel fuel blends, with or without additives, were compared with those of diesel fuel in a direct injection(DI) diesel engine. The experimental results indicated that the blend of ethanol with diesel fuel significantly reduced the concentrations of smoke, hydrocarbon(HC), and carbon monoxide(CO) in exhaust gas. Using 20% ethanol-diesel fuel blend with the additive of 2% of the total volume, the optimum mixing ratio was achieved, at which the bench diesel engine testing showed a significant decrease in exhaust gas. Bosch smoke number was reduced by 55%, HC emission by 70%, and CO emission by 45%, at 13 kW/1540 r/min. However, ethanol-diesel fuel blends produced a few ppm acetaldehydes and more ethanol in exhaust gas.     

氮氧化物的污染与治理方法

氮氧化物是大气的主要污染物之一,是治理大气污染的一大难题。本文介绍了氮氧化物的来源以及治理氮氧化物的主要方法,分析了这些方法处理氮氧化物的优点或缺点,并预测未来处理氮氧化物方法的发展趋势。     

城市污水再生回用于景观水体水质安全保障技术

研究了再生水回用于景观水体时可能存在的水质安全性问题,并提出了保障再生水安全回用的处理工艺。研究表明,城市污水再生水回用于景观水体时,存在着卫生学安全、毒理学安全、富营养化以及底质二次污染等危害。为了满足景观水体的水质标准,需要重点控制的水质指标有病原性微生物、有毒有害有机物、重金属、氮磷植物性营养物质、悬浮固体。以城市污水厂二级出水作为再生水原水时,推荐采用的工艺有:二级处理混凝沉淀过滤消毒、二级处理过滤活性炭吸附消毒以及二级处理膜处理消毒工艺。