A standardized approach for estimating the permeability of plastic films to soil fumigants under various field and environmental conditions

Minimizing atmospheric emissions of soil fumigants is critical for protecting human and environmental health. Covering the soil surface with a plastic tarp is a common approach to restrict fumigant emissions. The mass transfer of the fumigant vapors through the tarp is often the rate-limiting factor in fumigant emissions. An approach for standardizing measurements of film permeability is proposed that is based on determining the resistance (R) of films to diffusion of fumigants. Using this approach, values were determined for more than 200 film-chemical combinations under a range of temperature, relative humidity, and film handling conditions. Resistance to diffusion was specific for each fumigant/film combination, with the largest range of values observed for the fumigant chloropicrin. For each fumigant, decreased with increasing temperature. Changes in film permeability due to increases in temperature or field installation were generally less than a factor of five. For one film, values determined under conditions of very high relative humidity (approximately 100%) were at least 100 times lower than when humidity was very low (approximately 2%). This approach simplifies the selection of appropriate films for soil fumigation by providing rapid, reproducible, and precise measurements of their permeability to specific fumigants and application conditions.     

城市能源隧道开发潜力及效益分析北大核心CSCD

城市地区土地资源稀缺,使得20世纪以来城市地下空间的开发利用得以蓬勃发展。地下基础设施除了实现结构功能外,还可以作为浅层地热能采集系统与地层进行热量交换。在城市地区,交通隧道比建筑基础具有更广阔的作为能源地下结构的利用空间。以上海地铁为例,根据上海市的水文和地质环境,研究以城市尺度进行能源隧道建设的地热能开发潜力及其经济与社会效益。结果表明,与上海市2030年规划地铁线路同等规模的能源隧道的年度采集能量总量可达35亿kWh,经济收益超过15亿元,每年可减少CO_(2)排放量200万t以上,相当于上海市20%的住宅取暖或制冷所需的总能量,投入成本在10年左右可回收,说明能源隧道拥有巨大的开发潜力和广泛的应用前景。     

An automated systems for air sampling with annular denuder systems at a remote site

An automated air sampling system has been designed for use with the annular denuder system (ADS). The automated air sampling system allows for accurate measurements of air volume and day-night sampling while preventing the accumulation of moisture within the ADS caused by condensation or cloud events. The sampling system consists of air flow, monitoring and control subsystems. Calibration of the sampling system against a Hoffer turbine flow meter indicated accurate measurement of air flow volumes. Field testing and preliminary data have shown that the sampling system functions well in a remote mountain forest site, and was relatively unaffected by condensation, fog, or cloud events.     

天津城市水系统分析及行为模拟

在复合生态系统中,水作为一种物质流,是联系社会、经济、自然三个子系统的纽带.本文以天津城市生态系统为例,参考灵敏度模型的理论与方法,分析水系统各因素间的相互作用方式,模拟系统行为,以探讨缓解天津用水矛盾,促进持续发展的对策.     

FeCI3存在时六六六热解生成PCDD／Fs的研究

在开管体系中，于２８０℃时研究了六六六无效体在Ｆｅ，ＦｅＣＩ３存在时的热解，以及影响热解产物中ＰＣＤＤ／Ｆｓ生成量的因素。ＰＣＤＤ／Ｆｓ的生成主要取决于ＦｅＣＩ３，而Ｆｅ的存在并不增加体系中ＰＣＤＤ／Ｆｓ的生成量。在封管体系中，研究结果表明，ＰＣＤＤ／Ｆｓ的生成量随ＦｅＣＩ３用量、反应时间和反应温度的增加而增加，但温度影响最大。实验还表明，氯苯、氯酚对ＰＣＤＤ／Ｆｓ的生成起决定作用。在２５０－２８     

战略环境评价系统及工作程序

介绍了战略环境评价系统组成的五个要素 ,即评价者、评价对象、评价目的、评价标准和评价方法 ,分析了其相互关系及各要素与战略环境评价系统的关系 ,并提出了战略环境评价工作程序。     

二汽铸造二厂采用新设备防尘效果显著

二汽铸造二厂是一个生产汽车底盘毛坯的大型铸造厂,全厂配有70多台除尘设备。建厂初期,由于设计标准低,大多使用自制的湿式除尘器,排出的粉尘浓度远远达不到国家规定的排放标准。从1983年初起,该厂大搞技术改造,积极选用目前国内技术上较先进的微震反吹风扁布袋除尘     

苯酚标准贮备液稳定性实验

实验表明，苯酚标准贮备液放置一年后是稳定的，经统计检验无显著差异。