Removal of a complex VOC mixture by potted plants-effects on soil microorganisms.

Microorganisms in the soil of potted plants are important for removal of volatile organic compounds (VOCs) from indoor air, but little is known about the subject. The aim of this study was therefore to obtain a better understanding of the effect of VOCs on the microbial community in potted plants. Hedera helix was exposed to gasoline vapors under dynamic chamber conditions for 21 days and three main parameters were investigated. These were (1) removal of the target compounds heptane, 3-methylhexane, benzene, toluene, ethylbenzene, m,p-xylene, and naphthalene from the gasoline mixture; (2) toluene mineralization; and (3) bacterial abundance and bacterial community structure. H. helix was able to reduce the concentration of the target compounds in the continuously emitted gasoline by 25-32%, except for naphthalene, which was too low in concentration. The soil microcosm of gasoline exposed plants had for an initial 66 h increased toluene mineralization rate compared to the soil microcosm in the soil of plants exposed to clean air. Bacterial abundance was decreased in response to gasoline exposure while bacterial community structure was changed. The change in bacterial community structure was, however, different between the two experiments indicating that several taxonomic units can degrade gasoline components. Especially the genera Rhodanobacter and Pseudonorcardia significantly increased in abundance in response to gasoline vapors. Bauldia, Devosia, and Bradyrhizobium, on the other hand, decreased.

Occurrence and trophic transport of organic compounds in sedimentation ponds for road runoff.

Sedimentation ponds have been shown to accumulate several groups of contaminants, most importantly polycyclic aromatic compounds (PACs) and metals. But also, other urban organic pollutants have shown to be present, including polybrominated diphenyl ethers (PBDEs), organophosphate compounds (OPCs) and benzothiazoles (BTs). This investigation aimed at determining the occurrence of these four groups of contaminants in sedimentation ponds and determine their transport from water/sediment to organisms. PACs, including alkylated PACs, PBDEs; OPCs and BTs were determined in water, sediment, plants, dragonfly larvae and fish from two sedimentation ponds and one reference site. Fish were analysed for PAC metabolites. Overall, higher concentrations of all four pollutant groups were detected in water and sediment from sedimentation ponds compared to two natural lakes in rural environments (reference sites). The concentration difference was highest in sediments, and >20 higher concentration was measured in sedimentation ponds (3.6-4.4 ng/g ww) compared to reference (0.2 ng/g ww) for sum BDE6. For PACs and PBDEs a clear transport from water/sediment to organisms were observed. Fish were the highest trophic level organism (3.5-5) in our study, and all four pollutant groups were detected in fish. For PBDEs a trophic biomagnification (TMF) was found both in sedimentation ponds and reference, but higher concentrations in all matrices were measured in sedimentation ponds. TMF was not calculated for PACs since they are metabolised by vertebrates, but a transfer from water/sediment to organisms was seen. For BTs and OPCs, no consistent transfer to plants and dragonfly larvae could be seen. One OPC and two BTs were detected in fish, but only in fish from sedimentation ponds. It is therefore concluded that sedimentation ponds are hotspots for urban and traffic related contaminants, of which especially PACs and PBDEs are transferred to organisms living there.

Biomonitoring of Polycyclic Aromatic Hydrocarbon Deposition in Greenland Using Historical Moss Herbarium Specimens Shows a Decrease in Pollution During the 20th Century.

Although most point sources of persistent organic pollutants (POPs), including polycyclic aromatic hydrocarbons (PAHs), are at lower latitudes, the Arctic region is contaminated. In particular, PAHs now dominate the POP body burden of the region's marine biota at the lower trophic levels. Greenlandic Inuits have the most elevated levels of POPs in their blood compared to any other population, due to their consumption of seal meat and other marine mammals. PAHs, the by-products of the incomplete combustion of petroleum products, are known carcinogens and have been shown to affect the immune system, reproduction, endocrine functions, and the nervous system. With industrial activities and climate change set to increase local PAH emissions, it is paramount to document changes in atmospheric PAH deposition to further investigate PAH exposure in the region and attribute contaminations to their sources. As a measure of atmospheric pollution, we sampled bryophyte herbarium specimens of three common and widespread species collected in Greenland between the 1920s and 1970s after which time new collections were not available. They were analyzed for 19 PAHs using GC-MS (gas chromatography mass spectrometry). The presence of more low-molecular-weight PAHs than high-molecular-weight PAHs is evidence that the PAH contamination in Greenland is due to long-range transport rather than originating from local sources. The results show peaks in PAH atmospheric deposition in the first part of the 19th century followed by a trend of decrease, which mirror global trends in atmospheric pollution known from those periods. PAHs associated with wood and fossil-fuel combustion decrease in the 1970s coinciding with the disappearance of charcoal pits and foundries in Europe and North America, and a shift away from domestic heating with wood during the 19th century. The results highlight the value of bryophytes as bioindicators to measure PAH atmospheric pollution as well as the unrealized potential of herbaria as historical records of environmental change.

Removal of volatile gasoline compounds by indoor potted plants studied by pixel-based fingerprinting analysis.

Indoor potted plants are able to remove volatile organic compounds (VOC) from air, but only few studies have investigated the removal of compounds in mixtures. Here, we present a non-targeted pixel-based fingerprinting analysis documenting the removal of a complex mixture of gasoline VOCs by Hedera helix under dynamic chamber conditions allowing for air exchange and continuous gasoline exposure. For 15 days, the entire potted plant was exposed to gasoline; subsequently, the epigeous plant parts were removed and the soil microcosm (i.e. soil, plant roots and microorganisms) was exposed to gasoline for another eight days. Quantitative analysis was performed for heptane, 3-methylhexane, toluene, ethylbenzene and m,p-xylenes, and the CHEMSIC method (CHEMometric analysis of Selected Ion Chromatograms) was used for non-targeted pixel-based fingerprinting analysis. The quantitative analysis demonstrated that the presence of potted plants or pots without epigeous plant parts led to a reduction of selected VOCs by 16.7-22.6%. The CHEMSIC method confirmed this and revealed that all gasoline VOCs were reduced in concentration when H. helix was present. The estimate for the total VOC removal was in the range of 11-32%. The removal was highest for samples where the epigeous plant parts were absent and compounds known to be hard to degrade by microorganisms such as dimethylcyclopentanes were removed the least compared to compounds more easily degraded by microorganisms such as heptane when epigeous plant parts were removed. All findings support the conclusion that the soil microcosm was the main responsible for the removal of VOCs.

Can ornamental potted plants remove volatile organic compounds from indoor air? A review.

Volatile organic compounds (VOCs) are found in indoor air, and many of these can affect human health (e.g. formaldehyde and benzene are carcinogenic). Plants affect the levels of VOCs in indoor environments, thus they represent a potential green solution for improving indoor air quality that at the same time can improve human health. This article reviews scientific studies of plants' ability to remove VOCs from indoor air. The focus of the review is on pathways of VOC removal by the plants and factors affecting the efficiency and rate of VOC removal by plants. Laboratory based studies indicate that plant induced removal of VOCs is a combination of direct (e.g. absorption) and indirect (e.g. biotransformation by microorganisms) mechanisms. They also demonstrate that plants' rate of reducing the level of VOCs is influenced by a number of factors such as plant species, light intensity and VOC concentration. For instance, an increase in light intensity has in some studies been shown to lead to an increase in removal of a pollutant. Studies conducted in real-life settings such as offices and homes are few and show mixed results.

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/m(2)/h. The mode of toluene exposure (semi-dynamic or dynamic) had a significant influence on the removal rate obtained by H. helix.