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1.
The Swedish nationwide surveys of atmospheric heavy metal deposition in 1968/70 – 1995 using bryophytes (carpet-forming mosses) as monitors are reviewed. Considered are cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), mercury (Hg), nickel (Ni), vanadium (V), and zinc (Zn). The close agreement between data obtained with deposition (precipitation) collectors and moss carpet analysis is documented briefly, as well as measures of quality control and assessment of reproducibility. Since 1968/70, the deposition rate of the heavy metals considered has declined gradually and evenly, particularly in the southern parts of the country, reflecting an improvement of general air quality due to decreasing dust emission from mainly industry and fossil fuel combustion in northern and western Europe. By far the greatest absolute decrease in deposition rate was measured in Fe, which is a main constituent of most man-generated dust particles. However, the greatest per cent decreases in deposition rates were measured for Pb. The Pb concentration of moss carpets in Sweden as a whole in 1995 was only 11% of the value in 1968/70. Corresponding figures for Fe was 20%, Cd 24%, Ni 28%, Hg 31%, V 43%, Zn 51%, and Cu 52%. For Zn the current deposition rate seems to approach a natural baseline, whereas deposition of the other seven elements are still decreasing according to the surveys of 1990 and 1995.  相似文献   

2.
This paper provides an overview of the state of municipal solid waste (MSW) management in the capital of Cameroon, Yaoundé, and suggests some possible solutions for its improvement. The institutional, financial, and physical aspects of MSW management, as well as the livelihoods of the population, were analyzed. Our study revealed that distances and lack of infrastructure have a major impact on waste collection. Garbage bins are systematically mentioned as the primary infrastructure needed by the population in all quarters, whether it be a high or low standard community. The construction of transfer stations and the installation of garbage bins are suggested as a solution to reduce distances between households and garbage bins, thus improving waste collection vehicle accessibility. Transfer stations and garbage bins would enable the official waste collection company to expand its range of services and significantly improve waste collection rates. Several transfer stations have already been set up by non-governmental organizations (NGOs) and community-based organizations (CBOs), but they require technical, institutional and funding support. Research is needed on the quality and safety of community-made compost, as well as on soil fertility in urban and peri-urban areas. Most of the stakeholders, municipalities, the official waste collection company and households acknowledge the need for better monitoring and regulation of MSW management. The urban community of Yaoundé also needs to maintain its support of MSW management and promote the sustainability of NGOs and CBOs operating in underserved areas not yet covered by adequate infrastructures. A major opportunity for implementation of such waste policy is the heavily indebted poor countries (HIPC) program dedicated to urban planning and good governance.  相似文献   

3.
Providing good solid waste management (SWM) services while also ensuring financial sustainability of the system continues to be a major challenge in cities of developing countries. Bahir Dar in northwestern Ethiopia outsourced municipal waste services to a private waste company in 2008. While this institutional change has led to substantial improvement in the cleanliness of the city, its financial sustainability remains unclear. Is the private company able to generate sufficient revenues from their activities to offset the costs and generate some profit?This paper presents a cost-revenue analysis, based on data from July 2009 to June 2011. The analysis reveals that overall costs in Bahir Dar’s SWM system increased significantly during this period, mainly due to rising costs related to waste transportation. On the other hand, there is only one major revenue stream in place: the waste collection fee from households, commercial enterprises and institutions. As the efficiency of fee collection from households is only around 50%, the total amount of revenues are not sufficient to cover the running costs. This results in a substantial yearly deficit. The results of the research therefore show that a more detailed cost structure and cost-revenue analysis of this waste management service is important with appropriate measures, either by the privates sector itself or with the support of the local authorities, in order to enhance cost efficiency and balance the cost-revenues towards cost recovery. Delays in mitigating the evident financial deficit could else endanger the public-private partnership (PPP) and lead to failure of this setup in the medium to long term, thus also endangering the now existing improved and currently reliable service.We present four options on how financial sustainability of the SWM system in Bahir Dar might be enhanced: (i) improved fee collection efficiency by linking the fees of solid waste collection to water supply; (ii) increasing the value chain by sales of organic waste recycling products; (iii) diversifying revenue streams and financing mechanisms (polluter-pays-, cross-subsidy- and business-principles); and (iv) cost reduction and improved cost-effectiveness.We argue that in a PPP setup such as in Bahir Dar, a strong alliance between the municipality and private enterprise is important so that appropriate solutions for improved financial sustainability of a SWM system can be sought and implemented.  相似文献   

4.
Mexico is currently facing a crisis in the waste management field. Some efforts have just commenced in urban and in rural settlements, e.g., conversion of open dumps into landfills, a relatively small composting culture, and implementation of source separation and plastic recycling strategies. Nonetheless, the high heterogeneity of components in the waste, many of these with hazardous properties, present the municipal collection services with serious problems, due to the risks to the health of the workers and to the impacts to the environment as a result of the inadequate disposition of these wastes. A generation study in the domestic sector was undertaken with the aim of finding out the composition and the generation rate of household hazardous waste (HHW) produced at residences. Simultaneously to the generation study, a socioeconomic survey was applied to determine the influence of income level on the production of HHW. Results from the solid waste generation analysis indicated that approximately 1.6% of the waste stream consists of HHW. Correspondingly, it was estimated that in Morelia, a total amount of 442ton/day of domestic waste are produced, including 7.1ton of HHW per day. Furthermore, the overall amount of HHW is not directly related to income level, although particular byproducts do correlate. However, an important difference was observed, as the brands and the presentation sizes of goods and products used in each socioeconomic stratum varied.  相似文献   

5.
The conflict experienced in Turkey between adequate legal and legislative arrangements with weak capabilities of policy implementation and enforcement is a typical scenario experienced in developing countries. The difficulties faced in environmental management is increased by funding issues. Although environmental management is directly influenced by problems associated with the distribution of public funds, lack of funding is not the sole reason responsible for the mismanagement of resources. The paper seeks to answer whether the lack of funding allocated to ameliorate environmental degradation and pollution is the main reason for an environmental crisis situation in Turkey. Turkey needs to ensure implementation of the basic obligations stated in its environmental policy with respect to national and international issues. Specific obstacles Turkey needs to overcome for more effective environmental management will be examined within this context.  相似文献   

6.
This is a study of the sources of alkylphenol and alkylphenol ethoxylates in wastewater, including the new observation that the main contribution is from textiles. Alkylphenols and alkylphenol ethoxylates are widely used chemicals in various applications that are partly under environmental restrictions within Europe. The study sets out to analyze the most important sources of this large group of organic compounds in an urban wastewater system. A substance flow analysis (SFA) of the technosphere in Stockholm, Sweden in 2004 was conducted, allowing a comparison of 13 groups of goods’ emissions to wastewater. It was found that the groups of textiles and cleaning agents were the major sources to wastewater, while the group’s personal care products and paint and lacquers give smaller contributions. The content of alkylphenol ethoxylates in goods, especially in textiles, is a most significant source and is probably valid for other urban areas as well.  相似文献   

7.
Many different instruments exist which can be used in environmental policy. No one instrument is superior to all others in all situations. The instrument used in a specific situation depends on the goals to be achieved and on the specific environmental problem (for example, the number of polluters, monitoring problems, etc.). To manage more effectively present environmental issues it may be necessary to combine the use of traditional economic instruments with new economic mechanisms. An example is shown how such a new economic mechanism, a combination of the “utilitarian desires” rule and a tax rule, could assist to locate a new waste disposal site.  相似文献   

8.
9.
Used lead–acid battery (ULAB) recycling has caused numerous health and environmental issues in developing countries. Surface soil pollution from ULAB recycling activities has been linked with elevated levels of lead in human blood. We measured surface soil lead in and surrounding the ULAB recycling village of Hung Yen in northern Vietnam in 2011, 2013, and 2014. The data were analyzed statistically and discussed with respect to distance from the contamination source, year of measurement, contamination pathway, and countermeasures against the contamination. Transportation routes from the smelter or collection site displayed the greatest concentration of surface soil lead (median 6400–10,000 mg/kg). Surface soil lead decreased significantly with distance along the road from the ULAB recycling site, although such a decrease was not observed for rice fields, agricultural roads, or garden soil. Re-suspension and adherence by traffic were identified as key pollution pathways. Distance from the source, covering of the surface of roads, construction of walls, and position relative to the source were shown to be the most effective factors in the reduction of surface soil lead pollution. Application of a combination of these measures should result in improvement in the health of residents.  相似文献   

10.
The microbial strain Azotobacter vinelandii UWD was grown under conditions of simulated microgravity in the National Aeronautics and Space Administration (NASA) Bioreactor. Bacterial growth in simulated microgravity differed significantly from that observed in conventional shake flask experiments: Cells tended to grow in a cluster-like pattern and polymer production started immediately after exposing them to conditions of simulated microgravity, and no lag time was observed. It was imperative to differentiate between the effects derived from microgravity and those imposed by the altered oxygen supply in the bioreactor. Aeration conditions were studied in both reactor types and a gas supply profile was developed for the bioreactor. This supply profile allowed for similar amounts of dissolved oxygen in the bioreactor and the shake flask in the initial stage of the fermentation and, therefore, for an evaluation of the effects of microgravity on biopolyester-producing bacteria. Since the optical density that is conventionally used as a measure for the cell growth could not be used due to the cluster-like growth pattern of the cells, it was determined that bacterial growth behavior in the bioreactor can be monitored through glucose or oxygen consumption.  相似文献   

11.
Sampling of groundwater in theQuaternary deposits was carried out at 70 sitesin Stockholm for, among other things, metalanalyses. The objectives were to get a notion of the metal content and to get a basis for anestimation of the order of magnitude of thegroundwater transported metal contribution to themain surface water bodies in comparison to otherroutes. Thus, in three watershed areaswithin the Stockholm Town, groundwater flow andmetal concentration propagation were simulatedand metal fluxes were calculated. Theconcentrations of heavy metals were in generalfound to be very high in comparison withgroundwater in forested areas. This was mostpronounced for mercury (Hg) and copper (Cu). Themost remarkable result was a Hg concentration of4.57 g L-1 in the vicinity of a closed downhospital. The annual contribution of heavy metals(kg) by groundwater to the main surface waterbodies was estimated to: As (2.2), Cd (0.20), Co(4.9), Cr (3.1), Cu (34), Hg (0.06), Ni (28), Pb(2.2) Zn (118). These fluxes are much smallerthan those in forest ecosystems, due to lowergroundwater recharge in urban areas, where agreat part of the runoff is diverted bylandsealing, drainage, tunnels etc. The modelingresults emphasize the importance of the sorptionprocesses indicating that the modeled areas arein a non-steady state condition. It also showsthat the sources generating elevatedconcentrations of the high adsorptive metals Pband Hg are likely to be nearby.  相似文献   

12.
In view of the quantity of oil spilled, smaller spills generally receive less attention than headline grabbing incidents such as the “Amoco Cadiz”, “Exxon Valdez”, “Braer” and “Sea Empress”. The latter incidents involve the loss of significant quantities of oil, the establishment of relatively complex spill response management structures and the involvement of significant numbers of personnel and equipment. As such, large spills from tankers have the potential to create problem areas, for example in establishing and maintaining effective communications, logistics and resource management systems.In general terms spill response personnel are well aware that large spills come complete with significant operational and administrative problems, however what may not be so well recognised is that smaller spills also have the potential to present response personnel with their own unique problems.One of the major problems to be overcome when responding to spills in Australia is the “tyranny of distance”. In quite a few responses, Australian oil spill response managers have had to move personnel and equipment thousands of kilometres to provide an effective outcome. This paper outlines a range of problems that have been encountered by Australian personnel over the years. These include health and safety, communications, logistics and equipment issues.For the purpose of this paper a “smaller” spill has been defined as one involving a discharge of less than 1000 tonnes of oil.  相似文献   

13.
Two studies were conducted to determine a feasible and practical phytoremediation strategy for Zn-contaminated soils. The aim of the first study was to identify promising plant species capable of Zn remediation for the soils and climatic conditions of British Columbia. The purpose of the second study was to assess the effects of soil amendments in modifying the soil properties and providing the right conditions for the plants to immobilise Zn. Promising plants for phytostabilisation in the first study (Lolium perenne, Festuca rubra and Poa pratensis) were tested in the presence of soil amendments (lime, phosphate and compost, both individually and in combination) in the second study. The efficiency of treatments to stabilise Zn was based on Zn fractionation in the soil and on absorption and partitioning of Zn in plants. Maximum Zn immobilisation was achieved in the soil by a combination of lime, phosphate and compost, in conjunction with growth of P. pratensis.  相似文献   

14.
15.
During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown São Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, $ \rm NH^{ + }_{4} During the period from July 2002 to June 2004, the chemical characteristics of the rainwater samples collected in downtown S?o Paulo were investigated. The analysis of 224 wet-only precipitation samples included pH and electrical conductivity, as well as major ions (Na+, , K+, Ca2+, Mg2+, Cl, , ) and carboxylic acids (acetic, formic and oxalic) using ion chromatography. The volume weighted mean, VWM, of the anions , and Cl was, respectively, 20.3, 12.1 and 10.7 μmol l−1. Rainwater in S?o Paulo was acidic, with 55% of the samples exhibiting a pH below 5.6. The VWM of the free H+ was 6.27 μmol l−1), corresponding to a pH of 5.20. Ammonia (NH3), determined as (VWM = 32.8 μmol l−1), was the main acidity neutralizing agent. Considering that the H+ ion is the only counter ion produced from the non-sea-salt fraction of the dissociated anions, the contribution of each anion to the free acidity potential has the following profile: (31.1%), (26.0%), CH3COO (22.0%), Cl (13.7%), HCOO (5.4%) and (1.8%). The precipitation chemistry showed seasonal differences, with higher concentrations of ammonium and calcium during autumn and winter (dry period). The marine contribution was not significant, while the direct vehicular emission showed to be relevant in the ionic composition of precipitation.  相似文献   

16.
Matrix effects may increasingly lead to erroneous environmental decisions as regulatory limits or risk‐based concentrations of concern for trace metals move lower toward the limits of analytical detection. A U.S. Environmental Protection Agency Office of Technical Standards Alert estimated that environmental data reported using inductively coupled plasma spectrometry (ICP‐AES) has a false‐positive rate for thallium of 99.9 percent and for arsenic of 25 to 50 percent. Although this does not seem to be widely known in the environmental community, using three case studies, this article presents data in environmental samples that demonstrate severe matrix effects on the accuracy of arsenic and thallium results. Case Study 1 involves soil results with concentrations that approached or exceeded the applicable regulatory soil cleanup objectives of 13 mg/kg for arsenic and 2 mg/kg for thallium. Reanalysis using ICP coupled with a mass spectrometer (ICP‐MS) confirmed all thallium results were false positives and all arsenic results were biased high, concluding no action was required for soil remediation. Case Study 2 involves groundwater results for thallium at a Superfund site, where thallium was detected in groundwater up to 21.6 μ g/L using ICP‐AES. Reanalysis by ICP‐MS reported thallium as nondetect below the applicable regulatory level in all samples. ICP‐MS is usually a more definitive and accurate method of analysis compared to ICP‐AES; however, this is not always the case, as we demonstrate in Case Study 3, using data from groundwater samples at an industrial site. Through a weight‐of‐evidence approach, it is demonstrated that although method quality control results were acceptable, interferences in some groundwater samples caused biased high results for arsenic using ICP‐MS, which were significantly lower when reanalyzed using hydride generation atomic fluorescence spectrometry. Causes of these interference effects and conclusions from the three case studies to obtain accurate metal data for site assessment, risk characterization, and remedy selection are discussed. © 2010 Wiley Periodicals, Inc.  相似文献   

17.
An experimental study of methane–benzene binary mixture purification in a bench-scale reverse flow reactor is carried out. Results for catalytic oxidation of the two hydrocarbons with remarkably discrepant chemical properties show that autothermal catalytic combustion of very lean combustible concentration can be achieved with periodic feed reversal. Benzene is well removed, but methane conversion is relatively low and mainly determined by the thermal level of the reactor. If methane is added as auxiliary fuel to maintain autothermal operation when the volatile organic compound (VOC) concentration in the contaminated air is too low, an excess amount is needed. The influences of gas superficial velocity, cycle period, and methane-to-benzene ratio are discussed. A mathematical model is developed and solved using a FORTRAN code, with good correspondence being observed between the two approaches. Results of experimental and numerical study indicate that, during catalytic oxidation of lean VOCs in reverse flow reactor, the mutual inhibition effect between different kinds of hydrocarbon can be neglected.  相似文献   

18.
Injection-molded composites were prepared by blending PHBV5 with native cornstarch (30% and 50%) and with cornstarch precoated with PEO as a binding agent. These composites were evaluated for their biodegradability in municipal activated sludge by measuring changes in their physical and chemical properties over a period of 35 days. All composites lost weight, ranging from 45 to 78% within 35 days. Interestingly, the extent and rate of weight loss were quite similar in PHBV composites with no starch, with 30% starch, and with 50% starch. Weight loss was slowest in PHBV blends prepared with PEO-coated starch. For all samples, the weight loss was accompanied by a rapid deterioration in tensile strength and percentage elongation. The deterioration of these mechanical properties exhibited a relative rate of PHBV>starch-PHBV>PEO-coated starch-PHBV. Changes in starch/PHBV composition after biodegradation were quantified by FTIR spectroscopy. Increasing the starch content resulted in more extensive starch degradation, while the PHBV content in the blends became less susceptible to hydrolytic enzymes.The mention of firms names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over firms or similar products not mentioned. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, marital status, or handicap.  相似文献   

19.
Journal of Material Cycles and Waste Management - Nowadays, textile waste arising from increasing clothing production, consumption, and disposal activities has led to environmental, social, and...  相似文献   

20.
It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.  相似文献   

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