Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China

Particle density is an important physical property of atmospheric particles.The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles.In the present study,a centrifugal particle mass analyzer(CPMA) combined with a differential mobility analyzer(DMA) was deployed to determine the size-resolved effective density of 50 to 350 nm particles at a rural site of Beijing during summer 2016.The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55 g/cm~3,on average.The effective particle density distributions were dominated by a mode peaked at around 1.5 g/cm~3 for 50 to350 nm particles.Extra modes with peaks at 1.0,0.8,and 0.6 g/cm3 for 150,240,and 350 nm particles,which might be freshly emitted soot particles,were observed during intensive primary emissions episodes.The particle effective densities showed a diurnal variation pattern,with higher values during daytime.A case study showed that the effective density of Aitken mode particles during the new particle formation(NPF) event decreased considerably,indicating the significant contribution of organics to new particle growth.     

Diurnal variations of abiotic parameters in a stream,recipient for drainage water in Ranstad,southwest Sweden

During 24 h, water samples were taken for determination of a number of key parameters in a water system containing high concentrations of FeII at circumneutral pH. None of the major constituents (Ca, Mg, Na, K and sulfate) showed diurnal variations, while dissolved oxygen and pH increased during the night. This increase could entirely be explained by the decrease in water temperature. However, the concentration of FeII slightly increased at constant concentration of total Fe during the night, opposite to earlier observations in other systems where the presence of FeII was shown to be controlled by photoreduction. Nocturnal peaks of FeII have also been observed in other systems with high iron concentrations, however, at acidic pH, but without obvious explanation. The mechanisms for this process therefore need further investigation.     

Environmental assessment of supercritical water oxidation and other sewage sludge handling options.

Sustainable development relies on the eco-efficient use of all flows in society; more value created out of each resource unit. Supercritical water oxidation (SCWO) can be used for treatment of wet organic waste. The technology has been under development for over 20 years but has not yet been fully commercialized. SCWO allows for complete oxidation of all organics in sewage sludge and almost complete recovery of the inherent energy, essentially without harmful emissions. In this paper, a life-cycle assessment (LCA) of sewage sludge SCWO (Aqua-Critox) is presented and the results are compared with LCA results for other sludge handling options: agricultural use, co-incineration with municipal solid waste, incineration with subsequent phosphorus extraction (Bio-Con) and sludge fractionation with phosphorus recovery (Cambi-KREPRO). For SCWO, beneficial utilization of the heat of reaction is of crucial importance for the outcome. The electricity consumed by pumping and the nitrous oxide produced are other important parameters. The best sludge handling option from an environmental point of view depends on what aspect is considered more important in the impact assessment. Regarding global warming, the energy recovery methods perform better than agricultural use.     

The presence of zinc in Swedish waste fuels

Zinc (Zn) is a chemical element that has gained more attention lately owing to its possibility to form corrosive deposits in large boilers, such as Waste-to-Energy plants. Zn enters the boilers in many different forms and particularly in waste, the amount of Zn is hard to determine due to both the heterogeneity of waste in general but also due to the fact that little is yet published specifically about the Zn levels in waste. This study aimed to determine the Zn in Swedish waste fuels by taking regular samples from seven different and geographically separate waste combustion plants over a 12-month period. The analysis shows that there is a relation between the municipal solid waste (MSW) content and the Zn-content; high MSW-content gives lower Zn-content. This means that waste combustion plants with a higher share of industrial and commercial waste and/or building and demolition waste would have a higher share of Zn in the fuel. The study also shows that in Sweden, the geographic location of the plant does not have any effect on the Zn-content. Furthermore, it is concluded that different seasons appear not to affect the Zn concentrations significantly. In some plants there was a clear correlation between the Zn-content and the content of other trace metals.     

Project coordinators’ views on climate adaptation costs and benefits – justice implications

ABSTRACT

As local climate adaptation activity increases, so does the number of questions about costs, benefits, financing and the role that economic considerations play in adaptation-related decision-making and policy. Through five cases, covering a range of climate risks and types of adaptation measures, this paper critically examines Swedish project coordinators’ perceptions of costs and benefits in already-implemented climate adaptation measures. Our study finds that project coordinators make use of different system boundaries – on temporal, geographical and administrative scales – in their cost/benefit evaluations, making the practice of determining adaptation costs arbitrary and hard to compare. We further demonstrate that the project coordinators interpret costs and benefits in a manner that downplays the intangible environmental and social costs and benefits arising from the adaptation measures, despite their own experience of how such measures negatively impact upon social value. The exclusion of social and environmental costs and benefits has severe implications for justice, as it can bias decisions against people and ecosystems that are affected negatively. Based on the findings, we propose three tentative social justice dilemmas in local climate adaptation planning and implementation: 1. Cost and benefit distribution across scales; 2. The identification and valuation of non-market effects; and 3. The equitable allocation of costs and benefits.     

Parameterization and evaluation of sulfate adsorption in a dynamic soil chemistry model

Sulfate adsorption was implemented in the dynamic, multi-layer soil chemistry model SAFE. The process is modeled by an isotherm in which sulfate adsorption is considered to be fully reversible and dependent on sulfate concentration as well as pH in soil solution. The isotherm was parameterized by a site-specific series of simple batch experiments at different pH (3.8-5.0) and sulfate concentration (10-260 micromol 1(-1)) levels. Application of the model to the Lake Gardsj6n roof covered site shows that including sulfate adsorption improves the dynamic behavior of the model and sulfate adsorption and desorption delay acidification and recovery of the soil. The modeled adsorbed pool of sulfate at the site reached a maximum level of 700 mmol/m(2) in the late 1980s, well in line with experimental data.     

Distribution and leaching characteristics of trace elements in ashes as a function of different waste fuels and incineration technologies

Impact of waste fuels (virgin/waste wood, mixed biofuel (peat, bark, wood chips) industrial, household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr, As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature. Total concentration in ashes decreased in order of Zn > Cu > Pb > Cr > Sb > As > Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers (especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions. Concentration levels in ash and ash matrix properties (association of elements on ash particles) are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in > 50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.     

Preferences and willingness to pay for close to home nature for outdoor recreation in Sweden

In Sweden there is a strong tradition of using nature areas for outdoor recreation. This paper reports on a study which explored preferences and willingness to pay for outdoor recreation close to home (≤100 km away from home and ≤24 hours stay at a recreation site) using the contingent valuation method. The data originated from a mail survey that involved Swedish residents who were randomly selected from a national register. An ordinary least squares regression model was used to account for factors influencing willingness to pay. The results showed that approximately 50% of the respondents used nature areas close to their home for recreation and their average frequency of visits to these areas was 74 times annually. Areas dominated by forests were the most preferred, followed by water. The respondents were willing to pay approximately 7200 SEK (US$1080) annually. Their willingness to pay was influenced by factors such as type of nature area, distance to and time spent at the recreation site and income. The results provide one input to the land use planning process by considering the demand for nature-based outdoor recreation close to home.