Road traffic emission factors for heavy metals

Quantifying the emissions and concentrations of heavy metals in urban air is a prerequisite for assessing their health effects. In this paper a combination of measurements and modelling is used to assess the contribution from road traffic emissions. Concentrations of particulate heavy metals in air were measured simultaneously during 1 year at a densely trafficked street and at an urban background site in Stockholm, Sweden. Annual mean concentrations of cadmium were 50 times lower than the EU directive and for nickel and arsenic concentrations were 10 and six times lower, respectively. More than a factor of two higher concentrations was in general observed at the street in comparison to roof levels indicating the strong influence from local road traffic emissions. The only compound with a significantly decreasing trend in the urban background was Pb with 9.1 ng m^?3 in 1995/96 compared to 3.4 ng m^?3 2003/04. This is likely due to decreased emissions from wear of brake linings and reduced emissions due to oil and coal combustion in central Europe.Total road traffic emission factors for heavy metals were estimated using parallel measurements of NOx concentrations and knowledge of NOx emission factors. In general, the emission factors for the street were higher than reported in road tunnel measurements. This could partly be due to different driving conditions, since especially for metals which are mainly emitted from brake wear, more stop and go driving in the street compared to in road tunnels is likely to increase emissions. Total emissions were compared with exhaust emissions, obtained from the COPERT model and brake wear emissions based on an earlier study in Stockholm. For Cu, Ni and Zn the sum of brake wear and exhaust emissions agreed very well with estimated total emission factors in this study. More than 90% of the road traffic emissions of Cu were due to brake wear. For Ni more than 80% is estimated to be due to exhaust emissions and for Zn around 40% of road traffic emissions are estimated to be due to exhaust emissions. Pb is also mainly due to exhaust emissions (90%); a fuel Pb content of only 0.5 mg L^?1 would give similar emission factor as that based on the concentration increment at the street. This is the first study using simultaneous measurements of heavy metals at street and roof enabling calculations of emission factors using a tracer technique.     

A Comprehensive Inventory of the Ship Traffic Exhaust Emissions in the Baltic Sea from 2006 to 2009

This study addresses the exhaust emissions of CO₂, NO_x, SO_x, CO, and PM_2.5 originated from Baltic Sea shipping in 2006–2009. Numerical results have been computed using the Ship Traffic Emissions Assessment Model. This model is based on the messages of the automatic identification system (AIS), which enable the positioning of ships with a high spatial resolution. The NO_x emissions in 2009 were approximately 7 % higher than in 2006, despite the economic recession. However, the SO_x emissions in 2009 were approximately 14 % lower, when compared to those in 2006, mainly caused by the fuel requirements of the SO_x emission control area (SECA) which became effective in May 2006, but affected also by changes in ship activity. Results are presented on the differential geographic distribution of shipping emissions before (Jan–April 2006) and after (Jan–April 2009) the SECA regulations. The predicted NO_x emissions in 2009 substantially exceeded the emissions in 2006 along major ship routes and at numerous harbors, mostly due to the continuous increase in the number of small vessels that use AIS transmitters. Although the SO_x emissions have been reduced in 2009 in most major ship routes, these have increased in the vicinity of some harbors and on some densely trafficked routes. A seasonal variation of emissions is also presented, as well as the distribution of emissions in terms of vessel flag state, type, and weight.     

Is Levoglucosan a Suitable Quantitative Tracer for Wood Burning? Comparison with Receptor Modeling on Trace Elements in Lycksele,Sweden

Abstract

Particle emissions from residential wood combustion in small communities in Northern Sweden can sometimes increase the ambient particle concentrations to levels comparable to densely trafficked streets in the center of large cities. The reason for this is the combination of increased need for domestic heating during periods of low temperatures, leading to higher emission rates, and stable meteorological conditions. In this work, the authors compare two different approaches to quantify the wood combustion contribution to fine particles in Northern Sweden: a multivariate source-receptor analysis on inorganic compounds followed by multiple linear regression (MLR) of fine particle concentrations and levoglucosan used as a tracer. From the receptor model, it can be seen that residential wood combustion corresponds with 70% of modeled particle mass. Smaller contributions are also seen from local nonexhaust traffic particles, road dust, and brake wear (each contributing 14%). Of the mass, 1.5% is explained by long-distance transported particles, and 2% derives from a regional source deriving from either oil combustion or smelter activities.

In samples collected in ambient air, a significant linear correlation was found between wood burning particles and levoglucosan. The levoglucosan fraction in the ambient fine particulate matter attributed to wood burning according to the multivariate analysis ranged from <2% to 50%. This is much higher than the fraction found in the emission from the boilers expected to be responsible for most emissions at this site (between 3% and 6%). A laboratory emission study of wood and pellet boilers gave 0.3%_wt to 22%_wt levoglucosan to particle mass, indicating that the levoglucosan fraction may be highly dependent on combustion conditions, making it uncertain to use it as a quantitative tracer under real-world burning conditions. Thus, quantitative estimates of wood burning contributions will be very uncertain using solely levoglucosan as a tracer.     

Cost-Effectiveness of Alternative Strategies in Mitigating the Greenhouse Impact of Waste Management in Three Communities of Different Size

Mitigation and Adaptation Strategies for Global Change - Waste management is a significant source of methane (CH4) emissions. CH4 is second to carbon dioxide (CO2) the most important anthropogenic...     

Report: waste refinery in the municipality of Bor?s.

This paper briefly describes waste treatment trends in Sweden and describes an example of state-of-the-art treatment in a local integrated waste treatment system (Bor?s). The focus is on treatment of household waste, to illustrate what can be done to establish a sustainable waste treatment system with high recovery of materials and energy. The various processes have resulted in a low amount of landfilled household waste, and high proportions of recovered energy and materials. Heat, electricity, vehicle fuel and fertilizers, metals and construction materials are recovered from the local waste in Bor?s, with less than 4% of domestic waste being sent to landfill.     

Use of Industrial Hemp Fibers to Reinforce Wheat Gluten Plastics

The next generation of manufactured products must be sustainable and industrially eco-efficient, making materials derived from plants an alternative of particular interest. Wheat gluten (WG) is an interesting plant material to be used for production of plastic similar materials due to its film-forming properties. For usage of plastics in a wider range of applications, composite materials with improved mechanical properties are demanded. The present study investigates the possibilities of reinforcing WG plastics with hemp fibers. Samples were manufactured using compression molding (130 °C, 1600 bar, 5 min). Variation in fiber length, content (5, 10, 15 and 20 wt%) and quality (poor, standard, good) were evaluated. Mechanical properties and structure of materials were examined using tensile testing, light and scanning electron microscopy. Hemp fiber reinforcement of gluten plastics significantly influenced the mechanical properties of the material. Short hemp fibers processed in a high speed grinder were more homogenously spread in the material than long unprocessed fibers. Fiber content in the material showed a significant positive correlation with tensile strength and Young’s modulus, and a negative correlation with fracture strain and strain at maximum stress. Quality of the hemp fibers did not play any significant role for tensile strength and strain, but the Young’s modulus was significantly and positively correlated with hemp fiber quality. Despite the use of short hemp fibers, the reinforced gluten material still showed uneven mechanical properties within the material, a result from clustering of the fibers and too poor bonding between fibers and gluten material. Both these problems have to be resolved before reinforcement of gluten plastics by industrial hemp fibers is applicable on an industrial scale.