Toxicological characterization of particulate emissions from straw,Miscanthus, and poplar pellet combustion in residential boilers

Wood pellets have been used in domestic heating appliances for three decades. However, because the share of renewable energy for heating will likely rise over the next several years, alternative biomass fuels, such as short-rotation coppice or energy crops, will be utilized. We tested particulate emissions from the combustion of standard softwood pellets and three alternative pellets (poplar, Miscanthus sp., and wheat straw) for their ability to induce inflammatory, cytotoxic, and genotoxic responses in a mouse macrophage cell line. Our results showed clear differences in the chemical composition of the emissions, which was reflected in the toxicological effects. Standard softwood and straw pellet combustion resulted in the lowest PM₁ mass emissions. Miscanthus sp. and poplar combustion emissions were approximately three times higher. Emissions from the herbaceous biomass pellets contained higher amounts of chloride and organic carbon than the emissions from standard softwood pellet combustion. Additionally, the emissions of the poplar pellet combustion contained the highest concentration of metals. The emissions from the biomass alternatives caused significantly higher genotoxicity than the emissions from the standard softwood pellets. Moreover, straw pellet emissions caused higher inflammation than the other samples. Regarding cytotoxicity, the differences between the samples were smaller. Relative toxicity was generally highest for the poplar and Miscanthus sp. samples, as their emission factors were much higher. Thus, in addition to possible technical problems, alternative pellet materials may cause higher emissions and toxicity. The long-term use of alternative fuels in residential-scale appliances will require technological developments in both burners and filtration.

Copyright © 2016 American Association for Aerosol Research     

A process for designing algorithm-based personalized gamification

Multimedia Tools and Applications - Personalization is an upcoming trend in gamification research, with several researchers proposing that gamified systems should take personal characteristics into...     

Design and validation of an air-liquid interface (ALI) exposure device based on thermophoresis

In vitro, direct aerosol nanoparticle exposure of cells cultured at the air-liquid interface (ALI) has shown great potential over the conventional submerged cell exposure methods due to exposure relevancy and more accurate dose determination. Here, we present a design of an ALI cell exposure device, the thermocollector, which applies thermophoresis to deposit aerosol particles onto the cells. Computational numerical simulations were used to estimate the deposition flux and how it depended on particle properties. The deposition flux was approximately 250 particles/m²s for particles smaller than 100?nm, corresponding to an aerosol concentration of 1 #/cm³. This was also confirmed with experimental studies. For larger particles, the deposition rate depended more on particle properties; however, for fractal combustion derived soot particles, the deposition rate is practically size independent at the size range studied here. Finally, epithelial cells were exposed with wood combustion aerosol, and the toxicologic responses were investigated. The cell viability decrease and DNA damage were detected after the exposure. These effects were not detected in cells after the exposure to clean air in this cell exposure system.

Copyright © 2019 American Association for Aerosol Research     

The Significance of Ectomycorrhizas in Chemical Quality of Silver Birch Foliage and Above-Ground Insect Herbivore Performance

We tested whether the ectomycorrhizal (ECM) infection level of roots of silver birch (Betula pendula) affects performance of above-ground insect herbivores by increasing available plant biomass, by enhancing availability of nutrients, or by modifying concentration of defense compounds, i.e., phenolics, in birch foliage. Insect performance was determined for a phloem-feeding generalist (Lygus rugulipennis, the European tarnished plant bug), a phloem-feeding specialist (Calaphis flava, the birch aphid), and a chewing generalist (Epirrita autumnata, the autumnal moth larva). Silver birch plantlets had either natural ECM infection level (on average 24% of short roots with ECM), reduced ECM infection level with fungicide (F−, 9% ECM), or enhanced ECM infection level after inoculation with the fungus Paxillus involutus (PI+, 45% ECM) or Leccinum versipelle (LV+, 42% ECM). In general, the most pronounced effect of ECM was observed on growth of plantlets, i.e., stem growth decreased. In PI+-treated plants, leaf biomass also decreased. The effect of mycorrhizal colonization on the host plant’s nitrogen (N) and phosphorous (P) concentration was dependent on the mycorrhizal species and experiment. Fungicide treatment did not cause a consistent decrease in nutrients. Finally, defense of birch against herbivory, expressed as foliar phenolic concentration in plantlets, was not modified by ECM. However, E. autumnata had a significantly higher relative growth rate on PI+ plantlets with high leaf N concentration than on LV+ plantlets with low leaf N concentration. The birch aphid C. flava produced significantly less nymphs on birches with enhanced ECM infection levels (PI+ and LV+ plantlets) than on controls. In summary, our data show that the ECM infection level mainly affects the growth parameters of plantlets, whereas effects on leaf chemical quality are minor. Our data show that effects of ECM infection of birch roots on aboveground herbivores are multifaceted and depend on the fungal species forming ectomycorrhiza and also on the degree of specialization and feeding guild of insects.