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971.
本文研究了北京地区4种类型5个石灰性土壤样品对锰的吸附、及其与土壤各理化性质的关系。在每克土壤加入25ml10~200gMn/ml的剂量范围内,土壤对锰的吸附极好的遵从Freundrich等温方程,而是否符合Langmuir等温方程则与加入的锰溶液浓度有关,当其小于120 gMn/ml时,则能较好地符合Langmuir方程;这一现象说明,土壤具有两种或两种以上的吸附位。在土壤各理化性质中主要是粘粒含量和阳离于交换总量(CEC)影响到锰的吸附。但在锰溶液浓度较低时,各土壤理化性质均与土壤吸附锰量无显著相关。平衡溶液的pH强烈影响土壤吸附锰的能力,当pH由4上升至7左右时,土壤对锰的吸附急剧增加,pH值再上升,土壤吸附锰量的增加趋于平缓。 相似文献
972.
973.
Hung WT Tong HY Cheung CS 《Journal of the Air & Waste Management Association (1995)》2005,55(10):1431-1440
This study reports on the analysis of emissions and fuel consumption from motor vehicles using a modal approach. The four standard driving modes are idling, accelerating, cruising, and decelerating. On-road data were collected using instrumented test vehicles traveling many times through the urban areas of Hong Kong. A model was developed for estimating vehicular fuel consumption and emissions as a function of instantaneous speed and driving mode. Piecewise interpolation functions were proposed for each nonidling driving mode. Idling emission and fuel consumption rates were estimated as negative exponential functions of idling time. Preliminary modeling results showed good agreements for the test vehicles and indicated that the on-road measurements are feasible for the development of modal emission and fuel consumption models. 相似文献
974.
Many traditional water quality standards are based on extreme percentiles; often, there is the risk of making wrong decisions with these standards because of high estimation uncertainty. Standards expressed as fuzzy intervals in the form of [trigger, enforcement limitation] make it possible to control the risks for the discharger and the consumer simultaneously. With fuzzy interval compliance, corrective action is initiated when the trigger is exceeded; noncompliance is declared when the enforcement limitation is exceeded. Fuzzy intervals would digest the risks that are inherent when a single enforcement limitation is used to determine compliance; the risks can be further lowered when the fuzzy intervals are based on less extreme percentiles. This paper proposes several alternatives to using a single extreme percentile standard for regulating water quality or waste discharge. A case study using municipal effluent water quality data was included that suggests methods to determine compliance with fuzzy interval standards. 相似文献
975.
生物絮凝剂除浊脱色作用的初步研究 总被引:17,自引:0,他引:17
本文报道了产生NAT型生物絮凝剂的菌株的培养方法和筛选结果,着重讨论了此类生物絮凝剂对染料水样和非染料水样进行处理过程中pH值对处理效果的影响。并利用开发出的生物絮凝剂对实际排污河水进行处理,证明生物絮凝剂对悬浮水体的处理效果较好,可用于去除藻类。 相似文献
976.
生命周期评价与清洁生产 总被引:5,自引:0,他引:5
以清洁生产为主的污染“防止”战略将取代以末端处理为主的污染“防治”战略。评价一项清洁生产技术,需要采用生命周期评价的方法对工艺、产品和能源进行整个生命周期的环境影响和资源消耗的分析。本文主要介绍生命周期评价的基本概念和基本方法,评述生命周期评价的研究结果的应用范围,并给出了生命周期评价研究的一些实例。 相似文献
977.
仝青 《生态与农村环境学报》1994,(1)
报道了夏季蔬菜中有机磷农药残留量的调查。结果表明:在西红柿、青椒和豆角中,乐果平均残留量为0.081mg/kg,甲基对硫磷为0.015mg/kg,二嗪农为0.003mg/kg,而敌敌畏在这三种蔬菜中均未检出。夏季蔬菜中农药残留量的超标率甲基对硫磷>乐果>二嗪农>敌敌畏。三种蔬菜中,豆角的有机磷农药检出率最高,其次为青椒、西红柿。 相似文献
978.
979.
Qi Shihua Yan Jun Zhang Gan Fu Jiamo Sheng Guoying Wang Zhishi S. M. Tong U. W. Tang Min Yunshun 《Environmental monitoring and assessment》2001,72(2):115-127
Polycyclic aromatic hydrocarbons (PAHs), widespread environmental pollutants, have been measured in aerosols and dustfall in Macao. In this paper, we compare concentration distributions and determine the partitioning of PAHs in aerosols and dustfall for different areas, sampling times and sampling heights. The results demonstrate that the concentrations of PAHs in aerosols and dustfall vary at the different sites and heights. The concentrations of PAHs and most of the individual PAHs in aerosols at night were higher than those in the daytime when using the unit of g/g and lower than those when using the unit of g m-3. It is shown that the distribution of individual PAHs in aerosols differs significantly from that in dustfall. 相似文献
980.
Fenhuan Yang Chui Fong Lau Viki Wai Ting Tong Kiwi Kai Zhang Dane Westerdahl Simon Ng 《Journal of the Air & Waste Management Association (1995)》2019,69(1):47-57
Metropolitan residents are concerned about their exposure to airborne pollutants. But establishing these exposures is challenging. A compact personal exposure kit (PEK) was developed to evaluate personal integrated exposure (PIE) from time-resolved data to particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) in five microenvironments, including office, home, commuting, other indoor activities (other than home and office), and outdoor activities experienced both on weekdays and weekends. The study was conducted in Hong Kong. The PEK measured PM2.5, reported location and several other factors, stored collected data, as well as reported the data back to the investigators using global system for mobile communication (GSM) telemetry. Generally, PM2.5 concentrations in office microenvironment were found to be the smallest (13.0 μg/m3), whereas the largest PM2.5 concentration microenvironments were experienced during outdoor activities (54.4 μg/m3). Participants spent more than 85% of their time indoors, including in offices, homes, and other public indoor venues. On average, 42% and 81% of the time were spent in homes, which contributed 52% and 79% of PIE (during weekdays and weekends, respectively), suggesting that improvement of air quality in homes may reduce overall exposures and indicating the need for actions to mitigate possible public health burdens in Hong Kong. This study also found that various indoor/outdoor microenvironments experienced by urban office workers cannot be accurately represented by general urban air quality data reported from the regulatory monitoring. Such personalized air quality information, especially while in transit or in offices and homes, may provide improved information on population exposures to air pollution.
Implications: A newly developed personal exposure kit (PEK) was used to monitor PM2.5 exposure of metropolitan citizens in their daily life. Different microenvironments and time durations caused various personal integrated exposure (PIE). The stationary monitoring method for PIE was also compared and evaluated with PEK. Positive protection actions can be taken after understanding the major contribution to PM2.5 exposure. 相似文献