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1.
The interest in obtaining alternative fuels from waste sources and at the same time diminishing the impact of waste disposal has drawn attention to scrap tyres' carbon recovery. In order to thermally degrade used tyre rubber, a laboratory pyrolysis system was developed in this work. The installation devised focused on the production of liquid pyrolysates, where shredded rubber was supplied as the feedstock and nitrogen used as the carrier gas to provide an oxygen-free atmosphere. The variables affecting the performance of the process were investigated, including target temperature, heating rate and total residence time. Characterization of the volatile matter released was conducted by means of mass spectrometry to determine the composition of products, and particulate matter analysis to ascertain the aerosol content in the gas stream. The reproducibility of experiments, the influence of the temperature and time, and differences between the vapours before condensation and the exhaust gases are discussed. This work identified that the larger hydrocarbon fragments condense to constitute the oils, whereas the lighter molecules remain as non-condensable gases. This work also identified that the total number of nano-scale particles carried by the exhaust stream varies with temperature; significant changes in the composition of products and particle content were reported at approximately 400°C. The high number of nano-scale solid particulate matter present in the exhaust gases suggests that a thorough treatment for that stream would be required to avoid human health hazards.  相似文献   

2.
Emission rates of volatile organic compounds (VOCs) and ammonia measured from six PVC materials and four adhesives in the laboratory were compared to the emission rates measured on site from complete structures. Significantly higher specific emission rates (SERs) were generally measured from the complete structures than from individual materials. There were large differences between different PVC materials in their permeability for VOCs originating from the underlying structure. Glycol ethers and esters from adhesives used in the installation contributed to the emissions from the PVC covered structure. Emissions of 2-ethylhexanol and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) were common. High ammonia SERs were measured from single adhesives but their contribution to the emissions from the complete structure did not appear as obvious as for VOCs. The results indicate that three factors affected the VOC emissions from the PVC flooring on a structure: 1) the permeability of the PVC product for VOCs, 2) the VOC emission from the adhesive used, and 3) the VOC emission from the backside of the PVC product.  相似文献   

3.
Phosphate rocks are used extensively, mainly as a source of phosphorus for fertilizers and secondarily for phosphoric acid and other speciality chemicals. Phosphates are typically enriched in uranium and are thus one of the sources of technologically enhanced natural radiation (TENR) which increases exposure to man from natural radionuclides. Emissions from phosphate rock processing plants in gaseous and particulate form contain radionuclides, such as 238U and 226Ra, which are discharged into the environment causing radiation exposures to the population. About 10 MBq each of 238U and 226Ra are discharged into the environment each year from SICNG, a phosphate rock processing plant in Thessaloniki area, Northern Greece. The collective dose commitment to lung tissue resulting from atmospheric releases was estimated to be approximately 2 x 10(-9) person Gy t-1 for 238U and approximately 0.1 x 10(-9) person Gy t-1 for 226Ra, i.e. about 2 times higher than that estimated in the UNSCEAR reports issued in 1982, 1988, and 1993.  相似文献   

4.
Dust accumulating on hot indoor surfaces, e.g., heaters and light fixtures, are likely to emit chemicals when heated. Using in vitro techniques we have investigated biological effects of extracts from such emissions from three indoor and two outdoor dust samples heated at 50-250 degrees C. The cell cultures were a lung epithelial cell line (A549) and primary immune cells [peripheral blood mononuclear cell (PBMCs)]. We found that a 24-h incubation with extracts generated at 200 degrees C or higher inhibit both proliferation and mitochondrial activity of the epithelial cells. At non-cytotoxic concentrations, the extracts generated at 100 degrees C or higher inhibit the release of the pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) from lipopolysaccharide-stimulated PBMCs. The results imply that temperatures relevant for surfaces of equipment in the indoor environment cause emissions from dust that may have an impact on indoor air quality and affect the respiratory health of building occupants.  相似文献   

5.
从历史观和哲学观探讨环境安全问题的成因,将环境安全问题与工具的发明创造联系在一起,论述了环境安全问题就是工具的缺陷恶化了环境与人以及人类之间的和谐关系。环境安全问题不再是简单地针对环境的治理或对人的管理问题,而应该从工具的产生过程中寻找根本性的解决方案。工具的功能和性能设计,仅仅是完成工具设计的初步阶段。在投入社会之前,必须完成工具的人机环境设计与评估,用于平衡或消除工具所蕴含的潜在危险因素。因此,要解决环境安全问题,必须突破狭隘理念,以环境安全作为核心价值进行工业设计,创造与使用符合人机环境因素的优质工具。  相似文献   

6.
The Proserpina dam was built in Roman times to provide drinking water to Emerita Augusta (today's Mérida in SW Spain). During maintenance work, a sediment core was extracted, offering an excellent opportunity to analyze the historical environmental impacts of the dam and its reservoir over the 2000 years since Roman times. In order to establish an accurate chronology, 14C ages were determined by accelerator mass spectrometry (AMS). Core samples were assayed for their content in uranium and thorium series isotopes, 40K, and the anthropogenic radionuclides 137Cs, 90Sr, and 239+240Pu. Potassium-40 presented the highest activity level and was not constant with depth. The uranium and thorium series were generally in equilibrium, suggesting there had been no additional input of natural radionuclides. The presence of 137Cs was only found in relation with the global fallout in the early 1960s. Multi-element assays were performed using the PIXE and PIGE techniques. Some variations in the multi-element concentrations were observed with depth, but the sediment core could be considered as clean, and no presumptive anthropogenic pollutants were found. Nevertheless, an unusually high Zn content was detected at depths corresponding to pre-Roman times, due to geological anomalies in the area.  相似文献   

7.
应对全球气候变化,发展低碳经济已经成为中国发展的必然要求。金融发展在经济增长中起着重要作用,低碳经济发展离不开金融支持。低碳经济的实质是减少碳排放,因而需要厘清金融发展与碳排放之间的关系。通过测算中国1979-2008年碳排放的省际数据,建立P-VAR模型研究了中国区域金融发展与碳排放之间的动态关系。结果表明:地区碳排放量、地区金融发展深度和地区金融发展集中度三个变量之间存在着长期稳定的协整关系。脉冲响应分析结果显示:碳减排具有自我激励的性质;金融发展的深化、金融发展集中度的变化均对碳减排具有重要影响;区域金融发展的深化对人均碳排放具有显著的抑制作用;金融发展集中度的变化对碳减排的影响十分复杂,其变化若不能促进金融发展深度的提高,则可能阻碍碳减排。  相似文献   

8.
企业绿色管理已有研究将制度和技术在两个不同的领域进行分析,忽视了绿色管理是对制度和技术压力的反应,两种压力同时并存甚至相互影响.技术创新的"正外部性"和环境问题的"负外部性"要求在分析企业绿色管理行为时,整合制度和环境技术创新以及二者的相互关系.已有文献普遍强调作为强制性制度的环境规制对技术创新的驱动效果,而较少关注制度压力与技术创新的交互作用.通过对企业面临的制度压力和技术压力相互关系的分析,本文构建了基于制度与技术情境的企业绿色管理战略选择模型.企业绿色管理战略是制度压力和环境技术等因素相互作用的结果,对制度压力的反应有助于技术效率的提高,而企业所处的制度情境也影响到其对技术压力的响应方式.针对我国目前的环境监管现状,本文为制定有助于清洁技术采纳和扩散的环境政策提出相应建议.  相似文献   

9.
10.
Organochlorines such as PCBs, DDTs, HCHs, CHLs and HCB were determined in pooled whole body homogenized of fish samples collected from five locations during 1998 and 2003 in order to understand their contamination status, temporal and spatial variation in Indonesian waters. PCBs and DDTs were the predominant contaminants with concentrations from 9.7 to 2700 ng/g lipid wt. and 12 to 1100 ng/g lipid wt., respectively, while HCHs (nd-24 ng/g lipid wt.), CHL compounds (nd-81 ng/g lipid wt.) and HCB (0.22-28 ng/g lipid wt.) were one to two orders of magnitude lower. Among the locations, PCBs and CHLs were higher in the samples from highly industrialized and thickly populated-locations, whereas OC pesticides such as DDTs and HCHs were particularly more prominent in suburban and rural areas. Levels of OCs observed in the waters surrounding Java Island were higher than those in Sumatra Island, implying significant use of OCs in highly populated Java Island. Concentrations of PCBs and DDTs in fish from Jakarta Bay were significantly lower in the samples collected in 2003 as compared to fish in 1998, indicating decreasing trend of these compounds in the Indonesian environment. Recent estimated average daily intakes of PCBs (0.81 microg/person/day), DDTs (1.1 microg/person/day), HCHs (0.018 microg/person/day), CHLs (0.010 microg/person/day) were much lower than the threshold values recommended by various agencies, suggesting minimal risk of this compound via fish ingestion to Indonesians.  相似文献   

11.
This paper discusses cross-border cooperation at the level of urban socio-economic systems. Worldwide, cross-border urban cooperation has in several cases produced socio-economic and political coherence supported by various joint programs and efforts. However, the degree of coherence varies and seldom creates socio-economically and politically tightly integrated "Twin- Cities" where the state border becomes highly transparent or obscure. Focusing on Finlan d and China, our aim is to identify whether the selected border towns represent coherent TwinCities or a more loose type of "paired border towns". The study uses an empirical examination of three Finnish towns (Helsinki, Tornio, Imatra) and their neighboring towns in Estonia, Sweden, and Russia as a benchmark. Then, a comparative study is made regarding three Chinese cross-border cities facing Russia, Vietnam and Kazakhstan. We highlight the differences in cross-border integration from the viewpoint of shared public sector programs, cross-border enterprise relocation and networking, and integrated social sector in terms of labor market, education and shopping area.  相似文献   

12.
13.
The reverse osmosis process was evaluated for removal of naturally occurring arsenic and fluoride from groundwater. Arsenic removal was affected by the prevalent arsenic species present in the water. Arsenic concentrations were reduced by approximately 60%–90% from nearly 80 μg/L. Fluoride concentrations were reduced by approximately 60% from nearly 1.7 mg/L.  相似文献   

14.
As part of the BIOMOVS II study, a Working Group was established with the primary aim of comparing computer models used to assess the long-term impacts of contaminants released from uranium mill tailings piles, involving multiple pathways, multiple contaminants and multiple environmental receptors. The application of models to two scenarios (V1 and V2) allowed participants to gain an improved understanding of important processes and to compare the representation of these processes in the models. Partly as a result of this, new models were developed and the functionality of existing models was enhanced. Model results for the scenarios were compared quantitatively and agreed well (often within a factor of three) for the more tightly specified V2 scenario. In so far as the scenarios represent generic sites, the following generic conclusions can be drawn.
  • •A range of pathways and contaminants affect the total dose/intake and so no single pathway or contaminant is dominant for all scenarios to the exclusion of all other pathways or contaminants.
  • •Peak impacts on individuals may not arise for many hundreds of years.
  • •Simplification of the 238U decay chain, by assuming 210Pb and 210Po are in secular equilibrium in the biosphere with the long-lived parent, 226Ra, is inappropriate.
  • •Whilst models are available for assessing potential radiological and non-radiological health impacts, comparison of health impacts is limited by the absence of comprehensive data for health impacts of stable elements.
  相似文献   

15.
2012~2018年对神农架林区39个样点进行蜻蜒资源调查,考察期间共获得蜻蜓目昆虫2亚目15科55属88种.蜻蜓物种组成中,差翅亚目Anisoptera占绝对优势,共有34属61种,属、种比例分别为61.82%和69.32%,蜻科Libellulidae种类最多,共25种,占总种数的28.41%;神农架的束翅亚目Zygoptera共有21属27种,属、种比例分别为38.18%和30.68%,以色蟌科Calopterygidae、扇蟌科Platycnemididae和蟌科Coena-gnonidae占优势,各有5种,各占总种数的5.68%.神农架林区蜻蜓区系的主要特点是东洋种占优势,共有49种,占总种数的55.68%,包括4种分布类型;古北界-东洋界分布型有39种,占总种数的44.32%,包括9种分布类型.研究结果显示,神农架是重要的蜻蜒栖息地,蜻蜓资源具有显著的区域特色,为进一步保护蜻蜓多样性,应采取积极有效的保护策略.  相似文献   

16.
The gamma radiation emitted from a variety of commercial decorative granites available for use in U.S. homes has been measured with portable survey meters as well as an NaI(Th) gamma spectrometer. The 40K, U-nat, and 232Th activity concentrations were determined using a full-spectrum analysis. The dose rates that would result from two different arrangements of decorative granite slabs as countertops were explored in simulations involving an adult anthropomorphic phantom.  相似文献   

17.
A fast-growing bottled water market is occasionally challenged by reports calling for contaminant leaching from water-contact materials (plastics). Our focus was on leaching of antimony (Sb) and brominated compounds expressed by total soluble bromine (Br) measurements, including those of polybrominated diphenyl ethers (PBDE). Studies are lacking on concomitant leaching of two or more inorganic plastic constituents from the same bottle. A market-representative basket survey of bottled water was initiated in Boston, USA supermarkets. Bottled water classes sampled were: i) non-carbonated (NCR), ii) carbonated (CR), and iii) non-carbonated and enriched (NCRE). Plastic bottle materials sampled were: polyethylene terephthalate (PET), high-density polyethylene (HDPE), polystyrene (PS), and polycarbonate (PC). Storage conditions for the 31 bottled water samples were: 23 °C temperature, no-shaking and 12 h/12 h light/dark for 60 days of equilibration. Average Br and Sb concentrations after 60-days of storage followed the order of NCR < CR = NCRE, and NCR < CR < NCRE, respectively, suggesting that the presence of dissolved carbon dioxide in CR samples coupled to additions of flavors and color to NCRE could explain the elevated leaching of Br and Sb. Combining all bottled water classes and plastic material types, a highly significant (p < 0.001) correlation was observed between log-transformed soluble Br and Sb concentrations, suggesting similar leaching behavior. Among samples with the highest soluble Br concentrations, BDE-209 congener was qualitatively confirmed in three out of four bottled water samples. The PC, HDPE, and PS samples exhibited significantly (p < 0.05) lower Sb and Br leaching than PET. Upon quantitative validation of PBDE leaching from certain plastic bottles into water, a revisit to existing PBDE exposure assessment reports will be deemed necessary.  相似文献   

18.
Improved wood-burning stoves offer a possible solution that can simultaneously impact both problems of deforestation and problems of respiratory health in developing countries. We carried out a field experiment in which new fuel-efficient woodstoves were allocated in a Guatemalan village via the use of a lottery. A 2008 baseline survey was carried out on 2,148 individuals in 351 households, and then a follow-up survey was carried out in 2009, 4 months after households received the stoves. We found that households with the new stoves reduced wood consumption by an average of 59.1%. We also found indications of reductions in indoor air related health problems, where point estimates indicate a significant reduction in reported respiratory symptoms by 48.6% among women and 63.3% among children.  相似文献   

19.
The radon isotope 222Rn and salinity in coastal surface water were mapped on regional scales, to improve the understanding of coastal processes and their spatial variability. Radon was measured with a surface-towed, continuously recording multi-detector setup on a moving vessel. Numerous processes and locations of land-ocean interaction along the Central Great Barrier Reef coastline were identified and interpreted based on the data collected. These included riverine fluxes, terrestrially-derived fresh submarine groundwater discharge (SGD) and the tidal pumping of seawater through mangrove forests. Based on variations in the relationship of the tracers radon and salinity, some aspects of regional freshwater inputs to the coastal zone and to estuaries could be assessed. Concurrent mapping of radon and salinity allowed an efficient qualitative assessment of land-ocean interaction on various spatial and temporal scales, indicating that such surveys on coastal scales can be a useful tool to obtain an overview of SGD locations and processes.  相似文献   

20.
Groundwater samples were analysed for 222Rn, 226Ra, and 228Ra in Guarani aquifer spreading around 1 million km2 within four countries in South America, and it was found that their activity concentrations are lognormally distributed. Population-weighted average activity concentration for these radionuclides allowed to estimate a value either slightly higher (0.13 mSv/year) than 0.1 mSv for the total effective dose or two times higher (0.21 mSv/year) than this limit, depending on the choice of the dose conversion factor. Such calculation adds useful information for the appropriate management of this transboundary aquifer that is socially and economically very important to about 15 million inhabitants living in Brazil, Argentina, Uruguay and Paraguay.  相似文献   

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