Fine and ultrafine particles emitted from laser printers as indoor air contaminants in German offices

Purpose

Various publications indicate that the operation of laser printers and photocopiers may be associated with health effects due to the release of gaseous components and fine and ultrafine particles (UFP). However, only sparse studies are available that evaluate the possible exposure of office workers to printer emissions under real conditions. Therefore, the aim of our study was to assess the exposure of office workers to particulate matter released from laser printers and photocopiers.

Methods

Concentrations of fine particles and UFP were measured before, during, and after the operation of laser printing devices in 63 office rooms throughout Germany. Additionally, the particles were characterized by electron microscopy and energy-dispersive X-ray spectroscopy.

Results

A significant increase of fine particles and UFP was identified in ambient workplace air during and after the printing processes. Particle fractions between 0.23 and 20???m emitted by the office machines significantly affect particle mass concentrations while printing 500 pages, i.e., during the printing process, PM_0.23?C20, PM_2.5, and PM₁₀ concentrations increased in 43 out of the evaluated 62 office rooms investigated. Additionally, a significant increase was observed in submicrometer particles, with median particle number concentrations of 6,503 particles/cm³ before and 18,060 particles/cm³ during the printing process.

Conclusions

Our data indicate that laser printers and photocopiers could be a relevant source of fine particles and particularly UFP in office rooms.     

Transformation products and reaction kinetics of fragrances in advanced wastewater treatment with ozone

The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors.     

Three views of two degrees

Limiting global warming to 2°C above pre-industrial global mean temperature has become a widely endorsed goal for climate policy. It has also been severely criticized. We show how the limit emerged out of a marginal remark in an early paper about climate policy and distinguish three possible views of it. The catastrophe view sees it as the threshold separating a domain of safety from a domain of catastrophe. The cost-benefit view sees it as a strategy to optimize the relation between the costs and benefits of climate policy. The focal point view sees it as a solution to a complex coordination problem. We argue that the focal point view is the most appropriate. It leads to an emphasis on implementing effective steps toward a near-zero emissions economy, without panicking in the face of a possible temporary overshooting. After several decades of practical experiences, the focal point may or may not be redefined on the basis of knowledge gathered thanks to these experiences.     

Improving the aeration of critical fine-grained landfill top cover material by vegetation to increase the microbial methane oxidation efficiency

The natural methane oxidation potential of methanotrophic bacteria in landfill top covers is a sustainable and inexpensive method to reduce methane emissions to the atmosphere. Basically, the activity of methanotrophic bacteria is limited by the availability of oxygen in the soil. A column study was carried out to determine whether and to what extent vegetation can improve soil aeration and maintain the methane oxidation process. Tested soils were clayey silt and mature compost. The first soil is critical in light of surface crusting due to vertical erosion of an integral part of fine-grained material, blocking pores required for the gas exchange. The second soil, mature compost, is known for its good methane oxidation characteristics, due to high air-filled porosity, favorable water retention capacity and high nutrient supply. The assortment of plants consisted of a grass mixture, Canadian goldenrod and a mixture of leguminous plants. The compost offered an excellent methane oxidation potential of 100% up to a CH₄-input of 5.6 l CH₄ m⁻² h⁻¹. Whereas the oxidation potential was strongly diminished in the bare control column filled with clayey silt even at low CH₄-loads. By contrast the planted clayey silt showed an increased methane oxidation potential compared to the bare column. The spreading root system forms secondary macro-pores, and hence amplifies the air diffusivity and sustain the oxygen supply to the methanotrophic bacteria. Water is produced during methane oxidation, causing leachate. Vegetation reduces the leachate by evapotranspiration. Furthermore, leguminous plants support the enrichment of soil with nitrogen compounds and thus improving the methane oxidation process. In conclusion, vegetation is relevant for the increase of oxygen diffusion into the soil and subsequently enhances effective methane oxidation in landfill cover soils.     

“Just” ecopreneurs: re-conceptualising green transitions and entrepreneurship

Economic, environmental, and social limits of the current capitalist mode of production have led to a rethinking and reconceptualisation of economic processes and models including the role of businesses in sustainable development. While green economies and more specifically green entrepreneurs have been identified as agents of change that can challenge the mainstream and seek to induce environmental, social, and ethical transformation of society, much research has stayed within existing models of thinking predominantly rooted in technocratic approaches (e.g. ecological modernisation and more recently transition studies). This paper seeks to offer an alternative understanding of green entrepreneurship that breaks open these discussions using an environmental justice frame that focuses on the role of extra-economic discourses in shaping the social relations of economic systems. By drawing on an exemplary case study of “just” entrepreneurship from Boston, Massachusetts, USA, the paper seeks to start a conversation around the ideas of green entrepreneurship and environmental justice as vehicles to deliver potentially broader system changes and explores both conceptual and practical aspects of green development. As such, it offers (1) evidence of a just green economy that can be realised within existing capitalist structures as well as (2) a different conceptual entry point to understanding green entrepreneurship.     

Silver nanoparticles: behaviour and effects in the aquatic environment

This review summarises and evaluates the present knowledge on the behaviour, the biological effects and the routes of uptake of silver nanoparticles (Ag NPs) to organisms, with considerations on the nanoparticle physicochemistry in the ecotoxicity testing systems used. Different types of Ag NP syntheses, characterisation techniques and predicted current and future concentrations in the environment are also outlined. Rapid progress in this area has been made over the last few years, but there is still a critical lack of understanding of the need for characterisation and synthesis in environmental and ecotoxicological studies. Concentration and form of nanomaterials in the environment are difficult to quantify and methodological progress is needed, although sophisticated exposure models show that predicted environmental concentrations (PECs) for Ag NPs in different environmental compartments are at the range of ng L(-1) to mg kg(-1). The ecotoxicological literature shows that concentrations of Ag NPs below the current and future PECs, as low as just a few ng L(-1), can affect prokaryotes, invertebrates and fish indicating a significant potential, though poorly characterised, risk to the environment. Mechanisms of toxicity are still poorly understood although it seems clear that in some cases nanoscale specific properties may cause biouptake and toxicity over and above that caused by the dissolved Ag ion. This review concludes with a set of recommendations for the advancement of understanding of the role of nanoscale silver in environmental and ecotoxicological research.     

Differences in Dissolved Organic Carbon and Nitrogen Responses to Storm‐Event and Ground‐Water Conditions in a Forested,Glaciated Watershed in Western New York1

Abstract: Differences in the storm‐event responses of dissolved organic carbon (DOC) and nitrogen (DON) in streamflow and ground water were evaluated for a glaciated forested watershed in western New York. Eight to ten storm events with varying rainfall amounts, intensities, and antecedent moisture conditions were studied for three catchments (1.6, 3.4, and 696 ha) over a three‐year period (2003‐2005). Concentrations of DOC in streamflow exiting the catchments were significantly higher for storm events following a dry period, whereas no similar response was observed for DON. Highest DON concentrations in streamflow were typically associated with storm events following wet antecedent moisture conditions. In addition to antecedent moisture conditions, DOC concentrations were also positively correlated with precipitation amounts, while DON did not reveal a consistent pattern. Streamwater and ground‐water concentrations of DOC during storm events were also strongly correlated with riparian ground‐water depths but a similar relationship was not observed for DON. Ground‐water DON concentrations were also more variable than DOC. We hypothesized that the differences in DOC and DON responses stemmed from the differences in catchment sources of these solutes. This study suggests that while DOC and DON are intrinsically linked as components of dissolved organic matter, their dynamics and exports from watersheds may be regulated by a different set of mechanisms and factors. Identifying these differences is critical for developing more reliable and robust models for transport of dissolved organic matter.     

Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50kgNha(-1)y(-1) were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10kgNha(-1)y(-1) (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species.     

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay, Southeast China

In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays,Fujian Province,China,concentrations of organochlorine pesticides(hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs) and heavy metals(Cu,Pb,Zn,As,Cr,Cd,Ni and Hg) in 13 species collected from different sites in the bays were analyzed by GC-ECD and ICP-MS.The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples.Most of the organisms showed h...