蔬菜废物的两相厌氧消化产气研究

从Holbak丹麦废物处理厂收集的蔬菜废物进行了两相厌氧消化产气的研究。对水解条件，接种物质的添加，pH，及甲烷母液对消化产气的影响进行了考察。结果显示沥液循环实验的COD产率为67．9g／kg湿物质，VFA产率为44．7g/kg湿物质，产气为44．7g/kg湿物质；水冲实验的COD产率为128．2g/kg kg湿物质，VFA产率为128．0g／kg kg湿物质，产气为1281／kg湿物质，牛粪的添加使得蔬菜废物COD及VFA产率提高了30％。还发现以牛粪作为甲烷母液，在pH低于6．8时可以有高的甲烷初始产率。     

Worker influence on voluntary OHS management systems – A review of its ends and means

Voluntary management systems (MS) might improve occupational health and safety (OHS). MSs, as with any OHS management, requires worker influence (and management commitment) to reduce risks at work. Influence through union backed safety representatives (or similar) achieves the best OHS results. However, a MS guarantees neither effective OHS management nor strong worker influence. Systematic violations of legal requirements have repeatedly caused accidents at workplaces with certified MSs. Why employers introduce MS’s can affect their implementation and outcomes. Internal objectives, of productivity and/or work-related health, require upstream prevention and a genuine influence by workers and their safety representatives. However, managers with external objectives for a MS, such as brand images or low reported accident figures, may pursue such objectives through downstream control of safe behaviour – sometimes suppressing accident reporting – and with little attention to more serious long-term diseases. Worker consultation may then be a limited means of enhancing safety, or to one-way communication on safety rules. Such consultation may even be used for union busting. Many trade unions welcome MSs as possible improvement instruments, but they are also wary of what MSs employers are actually trying to implement. Unions try to support their safety representatives’ influence in a MS by enhancing their rights and their competences. If the motives for MSs are mainly external and the opportunities for influence too limited, it may be better for unions not to cooperate with management in a MS that may lead more to manipulation than to safe and sound work.     

Tri-decabrominated diphenyl ethers and hexabromocyclododecane in indoor air and dust from Stockholm microenvironments 2: indoor sources and human exposure

Data on polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) concentrations from Stockholm, Sweden, indoor microenvironments were combined with information from detailed questionnaires regarding the sampling location characteristics, including furnishing and equipment present. These were used to elucidate relationships between possible flame-retarded sources and the contaminant concentrations found in air and dust. Median concentration ranges of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD from all microenvironments were 19-570, 1.7-280, 29-3200 and < 1.6-2 pg/m³ in air and 22-240, 6.1-80, 330-1400 and 45-340 ng/g in dust, respectively. Significant correlations were found between concentrations of some PBDEs and HBCD in air and/or dust and the presence of electronic/electrical devices, foam furniture, PUF mattresses and synthetic bed pillows in, as well as floor area and construction year of the microenvironment. Car interiors were a source to indoor air in dealership halls. Using median and maximum concentrations of ΣPenta-, ΣOcta-, ΣDecaBDE and HBCD in air and dust, adult and toddler (12-24 months) intakes from inhalation and dust ingestion were estimated. Toddlers had higher estimated intakes of ΣPenta-, ΣDecaBDE and HBCD (7.8, 43, 7.6 ng/d, respectively) from dust ingestion than adults (5.8, 38, 6.0 ng/d, respectively). Air inhalation in offices was also an important exposure pathway for ΣPenta-, ΣOcta- and ΣDecaBDE in adults. For ΣPentaBDE and HBCD, air inhalation and dust ingestion play minor roles when compared to previously published Swedish dietary intakes (median exposures). However, in worst case scenarios using maximum concentrations, dust ingestion may represent 77 and 95% of toddler intake for ΣPentaBDE and HBCD, respectively.     

Polybrominated diphenyl ether exposure to electronics recycling workers--a follow up study

Workers at an electronics recycling plant have previously been shown to have elevated serum levels of polybrominated diphenyl ethers (PBDEs) compared to referents without occupational PBDE exposure. Subsequent structural changes and industrial hygiene measures at the plant were applied to improve the work environment. The present study aims to assess the impact of these work environment changes on the occupational exposure to PBDEs.

Blood were drawn from the workers and analyzed at two different laboratories, and serum concentrations of several PBDE congeners were determined by GC/MS or GC/HRMS. Cross-sectional studies were performed prior to (in 1997; N = 19) and after (in 2000; N = 27) workplace improvements. Longitudinal studies were performed on twelve of the workers that were sampled at both occasions.

Even though the amount of processed goods had doubled in 2000 as compared to 1997, there was a significant decrease in the serum levels of BDE-183 and BDE-209. For BDE-209 the levels observed in year 2000 were even lower than in referents with no occupational exposure. In contrast to the decrease of higher brominated diphenyl ethers, the concentrations of BDE-47 did not significantly change. For BDE-153, the cross-sectional study indicated no change, whereas the longitudinal follow up indicated a significant increase.

This study shows that the industrial hygiene improvements clearly reduced the occupational exposure to BDE-183 and BDE-209 at the plant. Still, the levels of hexa- to nonaBDEs but not BDE-209 were elevated, compared to referents with no occupational exposure.     

Experimental measurement and modeling of the rate of absorption of carbon dioxide by aqueous ammonia

In this work, the rate of absorption of carbon dioxide by aqueous ammonia solvent has been studied by applying a newly built wetted wall column. The absorption rate in aqueous ammonia was measured at temperatures from 279 to 304 K for 1 to 10 wt% aqueous ammonia with loadings varying from 0 to 0.8 mol CO₂/mol NH₃. The absorption rate in 30 wt% aqueous mono-ethanolamine (MEA) was measured at 294 and 314 K with loadings varying from 0 to 0.4 as comparison.It was found that at 304 K, the rate of absorption of carbon dioxide by 10 wt% NH₃ solvent was comparable to the rates for 30 wt% MEA at 294 and 314 K (a typical absorption temperature for this process). The absorption rate using ammonia was however significantly lower at temperatures of 294 K and lower as applied in the Chilled Ammonia Process. However, at these low temperatures, the rate of absorption in ammonia has only a small temperature dependency.The rate of absorption decreases strongly with decreasing ammonia concentrations and increasing CO₂ loadings.The rate of absorption of carbon dioxide by aqueous ammonia solvent was modeled using the measurements of the unloaded solutions and the zwitter-ion mechanism. The model could successfully predict the experimental measurements of the absorption rate of CO₂ in loaded ammonia solutions.     

NitroGenius: a nitrogen decision support system. A game to develop the optimal policy to solve the Dutch nitrogen pollution problem

A nitrogen decision support system in the form of a game (NitroGenius) was developed for the Second International Nitrogen Conference. The aims were to: i) improve understanding among scientists and policy makers about the complexity of nitrogen pollution problems in an area of intensive agricultural, industrial, and transportation activity (The Netherlands); and ii) search for optimal policy solutions to prevent pollution effects at lowest economic and social costs. NitroGenius includes a model of nitrogen flows at relevant spatial and temporal scales including emissions of ammonia and nitrogen oxides and contamination of surface- and groundwaters. NitroGenius also includes an economic model describing relationships for important sectors and impacts of different nitrogen control measures on Gross Domestic Product (GDP), unemployment, energy use, and environmental costs. About 50 teams played NitroGenius during the Second International Nitrogen Conference. The results show that careful planning and selection of abatement options can solve Dutch nitrogen problems at reasonable cost.     

Aqueous photolysis of the iron (III) complexes of NTA, EDTA and DTPA

The rate of photolysis of iron complexes with three common complexing agents, NTA, EDTA and DTPA was analysed. Aqueous solutions of each complex were illuminated in a Xenotest 1200. Using a sun spectrum from 60°N (Stockholm latitude), environmentally related half lifetimes were calculated.

The half lifetimes were 43, 11 and 8 min for the three 1:1 complexes, resp., dissolved in the top layer of a water system and illuminated at the yearly maximum of sun light in the specified area. In the environment several factors operate to reduce this rate. However, photolytic degradation pathways seem to be an important environmental fate of these substances.     

Pikeperch (Sander lucioperca (L.)) in Decline: High Mortality of Three Populations in the Northern Baltic Sea

The development of three pikeperch (Sander lucioperca (L.)) populations in the northern Baltic Sea was monitored using standardized multimesh gillnets in 1995–2009. Declining trends in the abundances of pikeperch over 40 cm total length, low numbers of individuals older than 6 years, and high mortality rates were observed in all three populations. In the site with the largest commercial catches per unit area and a rapidly increased colony of great cormorants (Phalacrocorax carbo sinensis Blumenbach 1798), also the abundance of pikeperch below 40 cm total length and year-class strength showed declining trends. The adverse population level changes did not correlate with changes in water quality or eutrophication status. Together, the results suggest that in all study sites fisheries are harvesting a large proportion of the pikeperch soon after or even before reaching the maturity, and that predation from great cormorants may increase mortality of juveniles. Pikeperch is important not only for fisheries but also for ecosystem functioning, and our results point at the need for further management measures to ensure viable populations in the areas studied.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-013-0429-z) contains supplementary material, which is available to authorized users.     

Analysis of mono- to deca-brominated diphenyl ethers in chickens at the part per billion level

Polybrominated diphenyl ethers (PBDEs) are flame retardants which have been found to be increasing in the environment. Because of structural similarities to the polychlorinated biphenyls and concerns that PBDEs may be widespread, we have investigated their presence in a food source, namely chickens. A GC-MS method was developed to analyze mono- through deca-BDEs in chicken fat samples. The method utilized GC pressure programming and selected ion monitoring to quantitate PBDEs at the low part per billion level. Four 13C-labeled surrogates were used to determine recoveries; recoveries averaged from 76% to 114%. Thirteen chickens from the Southern US and a composite sample of chickens from North Dakota were analyzed by this method. The total concentrations of PBDEs on a whole weight basis ranged from 1.7 ppb in North Dakota chickens to 39.4 ppb in a chicken from Arkansas. On a lipid weight basis, these levels were lower than those generally found in fish and fish-eating mammals. The PBDE pattern was also different from other samples reported; penta-BDEs rather than tetra-BDEs were the most prominent congeners.