Assessment of volatile organic compound removal by indoor plants—a novel experimental setup

Indoor plants can remove volatile organic compounds (VOCs) from the air. The majority of knowledge comes from laboratory studies where results cannot directly be transferred to real-life settings. The aim of this study was to develop an experimental test system to assess VOC removal by indoor plants which allows for an improved real-life simulation. Parameters such as relative humidity, air exchange rate and VOC concentration are controlled and can be varied to simulate different real-life settings. For example, toluene diffusion through a needle gave concentrations in the range of 0.10–2.35 μg/L with deviations from theoretical values of 3.2–10.5 %. Overall, the system proved to be functional for the assessment of VOC removal by indoor plants with Hedera helix reaching a toluene removal rate of up to 66.5 μg/m²/h. The mode of toluene exposure (semi-dynamic or dynamic) had a significant influence on the removal rate obtained by H. helix.     

5,000 year-old spermatozoa in Quaternary Ostracoda (Crustacea)

Fossil spermatozoa are recorded for the first time in freshwater ostracods (small bivalved crustaceans) from Holocene sediments at sites in the United Kingdom and Germany. Exceptional conditions at these sites have resulted in the preservation of chitinous "soft parts", including limbs, the remains of Zenker's Organs (sperm pumps that are part of the male reproductive apparatus in cypridoidean ostracods) and spermatozoa from eight different species. Comparisons are made with spermatozoa from living ostracods and the implications of these discoveries for evolutionary studies of reproductive modes are discussed.     

Metallakkumulation in Moosen: Standörtliche und regionale Randbedingungen des Biomonitoring von Luftverunreinigungen

Goal and Scope

Several studies show that the concentration of metals in mosses depends not only on metal deposition but also on factors such as moss species, canopy drip, precipitation, altitude, distance to the sea and the analytical technique used. However, contrasting results have been reported and the interpretation of the spatial variability of the metal accumulation in mosses remains difficult. In the presented study existing monitoring data from the European Heavy Metals in Mosses Surveys together with surface data on precipitation, elevation and land use are statistically analysed to assess factors other than emissions that have an influence on the metal accumulation in the mosses.

Main Features

Inference statistics and Spearman correlation analysis were applied to examine the association of the metal accumulation and the distance of the monitoring sites to the sea as well as the altitude. Whether or not significant differences of the metal loads in the mosses exist at national borders was examined with help of the U-test after Mann and Whitney. In order to identify and rank the factors that are assumed to have an influence on the metal uptake of the mosses Classification and Regression Trees (CART) were applied.

Results

No clear tendency could be derived from the results of the inference statistical calculations and the correlation analyses with regard to the distance of the monitoring site to the sea and the altitude. According to the results of the CART-analyses mainly the moss species, potential emission sources around the monitoring sites, canopy drip and precipitation have an effect on the metal bioaccumulation. Assuming that each participating country followed strictly the manual for sampling and sample preparation the results of the inference statistical calculations furthermore suggest that in most cases different techniques for digestion and analysis bias the measurements significantly.

Discussion

For the first time a national monitoring data base consisting of measurement data and metadata as well as surface information on precipitation, land use and elevation was applied to examine influence factors on the metal bioaccumulation in mosses. The respective results mirror existing knowledge from other national studies to a large extend, although further analyses are necessary to affirm the findings. These analyses should include data from other national monitoring programmes and should additionally be carried out with other decision tree algorithms than CART.

Conclusions

The local variability in the metal concentration in mosses can be uncovered in terms of predictors or underlying hidden causes by using CART. Ideally, such an approach should be applied across the whole of Europe. This will only be feasible if all participating countries provide additional information about site characteristics as currently is done in for example the German moss surveys.

Recommendations

The UNECE Metals in Mosses Survey experimental protocol should be improved in order to reduce the observed influences, to enhance standardisation, and to strengthen the quality control. This implies the integration of sampling site describing metadata into the assessment. Furthermore, basis research is needed to test the hypothesis concerning moss species-specific accumulation of depositions.

Perspectives

Provided that the presented results hold true in further analyses correction factors should be applied on the moss data in order to get the depicted spatial patterns and temporal trends of metal bioaccumulation unbiased. Such factors should be calculated for natural landscape units or ecoregions that are homogeneous with regard to climate, vegetation and altitude.     

Intra- and inter-annual variability of VOC emissions from natural and semi-natural vegetation in Europe and neighbouring countries

Biogenic VOC emission estimates from the earth's surface are crucial input parameters in air quality models. Knowledge accumulated in the last years about BVOC source distributions and chemical compound species emission profiles in Europe as well as the demand of air quality modellers for a finer resolution in space and time of BVOC estimates have led to the set-up of new emission modelling systems. An updated fast BVOC emission modelling platform explicitly considering the seasonality of emission potentials and leaf temperature gradients in forest canopies by the semi-empirical emission module (seBVOC) will be proposed and used for estimating hourly values of chemical compound-specific emissions in Europe (33–68° north; 10° west to 40° east) in the years 1997, 2000, 2001, and 2003. Spatial resolution will be 10 km by 10 km. The database used contains latest land and forest distributions, updated foliar biomass densities, leaf area indices (LAI), and plant as well as chemical compound-specific emission potentials, if available. Meteorological input parameters for the respective years will be generated using the non-hydrostatic meteorological model MM5. Highest BVOC emissions occur in daytime hours around noon from the end of May to mid-August in the Mediterranean area and from the mid of June to the end of July in the boreal forests. Comparison of 3 BVOC model approaches will reveal that for July 2003, the European isoprene and monoterpene totals range from 1124 Gg to 1446 Gg and from 338 Gg to 1112 Gg, respectively. Small-scale deviations may be as high as ±0.6 Mg km^?2 for July 2003, reflecting the current uncertainty range for BVOC estimates. Key sources of errors in inventories are still insufficiently detailed land use data for some areas and lacking chemically speciated plant-specific emission potentials in particular in boreal, south-eastern, and northern African landscapes. The hourly emissions of isoprene, speciated terpenes, and oxyVOC have been made available by the NatAir database.     

Polybrominated diphenyl ethers (PBDEs) and alternative brominated flame retardants in air and seawater of the European Arctic

The spatial distribution of polybrominated diphenyl ethers (PBDEs) and several alternative non-PBDE, non-regulated brominated flame retardants (BFRs) in air and seawater and the air-seawater exchange was investigated in East Greenland Sea using high-volume air and water samples. Total PBDE concentrations (Ó₁₀PBDEs) ranged from 0.09 to 1.8 pg m⁻³ in the atmosphere and from 0.03 to 0.64 pg L⁻¹ in seawater. Two alternative BFRs, Hexabromobenzene (HBB) and 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE), showed similar concentrations and spatial trends as PBDEs. The air-seawater gas exchange was dominated by deposition with fluxes up to −492 and −1044 pg m⁻² day⁻¹ for BDE-47 and DPTE, respectively. This study shows the first occurrence of HBB, DPTE and other alternative flame retardants (e.g., pentabromotoluene (PBT)) in the Arctic atmosphere and seawater indicating that they have a similar long-range atmospheric transport potential (LRAT) as the banned PBDEs.     

On the Curing of ESO/MTHPA/DEH 35 and ESO/MTHPA/DEH 35/TIN

Journal of Polymers and the Environment - Epoxidized soybean oil (ESO) compounds were cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6-tris (dimethylaminomethyl) phenol...