Current issues and uncertainties in the measurement and modelling of air-vegetation exchange and within-plant processing of POPs.

Air-vegetation exchange of POPs is an important process controlling the entry of POPs into terrestrial food chains, and may also have a significant effect on the global movement of these compounds. Many factors affect the air-vegetation transfer including: the physicochemical properties of the compounds of interest; environmental factors such as temperature, wind speed, humidity and light conditions; and plant characteristics such as functional type, leaf surface area, cuticular structure, and leaf longevity. The purpose of this review is to quantify the effects these differences might have on air/plant exchange of POPs, and to point out the major gaps in the knowledge of this subject that require further research.

Seasonal and long-term trends in atmospheric PAH concentrations: evidence and implications.

Atmospheric monitoring data for selected polynuclear aromatic hydrocarbons (PAHs) were compiled from remote, rural and urban locations in the UK, Sweden, Finland and Arctic Canada. The objective was to examine the seasonal and temporal trends, to shed light on the factors which exert a dominant influence over ambient PAH levels. Urban centres in the UK have concentrations 1-2 orders of magnitude higher than in rural Europe and up to 3 orders of magnitude higher than Arctic Canada.

The development of phenanthrene catabolism in soil amended with transformer oil.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants frequently associated with light non-aqueous-phase liquids (LNAPLs) in soil. Microbial degradation comprises a major loss process for PAHs in the environment. Various laboratory studies, using known degraders, have shown reduced or enhanced mineralisation of PAHs when dissolved in different LNAPLs.

Study of plant-air transfer of PCBs from an evergreen shrub: implications for mechanisms and modeling.

The depuration of gas-phase polychlorinated biphenyls (PCBs) from a slow-growing evergreen shrub, Skimmia japonica Thunb., was studied to investigate the reversibility of uptake and the compartmentalization of PCB congeners within leaves with respect to air-plant exchange processes. Depuration of PCBs was monitored over periods of hours, days, and weeks.

Comparative potency of some extended peptide chain members of the RFamide neuropeptide family, assessed on the hearts of Busycon canaliculatum and Buccinum undatum.

Twenty different RFamide neuropeptide analogues were examined for their relative potencies on the ventricles of Busycon canaliculatum and Buccinum undatum and on the atrium of Busycon to determine the essential requirements for activity at the RFamide receptor. None of the neuropeptide studies was inhibitory to natural cardiac rhythmicity or to FMRFamide (Phe-Met-Arg-Phe-NH(2)) or FLRFamide (Phe-Leu-Arg-Phe-NH(2)) responses. Two tripeptides studied were completely without effect, indicating that a minimum of four amino acids in the peptide chain length was essential for any activity.

Arsenic speciation in the earthworms Lumbricus rubellus and Dendrodrilus rubidus.

Two species of earthworm, Lumbricus rubellus Hoffmeister and Dendrodrilus rubidus (Savigny) collected from an arsenic-contaminated mine spoil site and an uncontaminated site were investigated for total tissue arsenic concentrations and for arsenic compounds by liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). For L. rubellus, whole-body total tissue arsenic concentrations were 7.

Global distribution and budget of PCBs and HCB in background surface soils: implications for sources and environmental processes.

This paper presents data from a survey of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) concentrations in 191 global background surface (0-5 cm) soils. Differences of up to 4 orders of magnitude were found between sites for PCBs. The lowest and highest PCB concentrations (26 and 97,000 pg/g dw) were found in samples from Greenland and mainland Europe (France, Germany, Poland), respectively.

PAHs, PCBs, PCNs, organochlorine pesticides, synthetic musks, and polychlorinated n-alkanes in U.K. sewage sludge: survey results and implications.

A survey of the digested sludge from 14 U.K. wastewater treatment plants was carried out to obtain contemporary U.

Spatial and temporal trends of POPs in Norwegian and UK background air: implications for global cycling.

Data are presented for PCBs and HCB measured by passive air samplers (SPMDs) along a latitudinal transect from the south of the UK to the north of Norway during 1998-2000. This work is part of an ongoing air sampling campaign in which data were previously gathered for 1994-1996. Comparisons of the masses of chemicals sequestered by the SPMDs during these different time intervals are used to investigate spatial and temporal trends.

The application of proton transfer reaction-mass spectrometry (PTR-MS) to the monitoring and analysis of volatile organic compounds in the atmosphere.

Proton transfer reaction-mass spectrometry (PTR-MS) is a new and emerging technique for the measurement and monitoring of volatile organic compounds (VOCs) at low concentrations in gaseous samples in more-or-less real time. Utilising chemical ionisation, it combines the desirable attributes of high sensitivity and short integration times with good precision and accuracy. Recently it has been exploited in applications related to atmospheric science.

Fate of 1,2,3,4,6,7,8-heptachlorodibenzofuran and pentachlorophenol during laboratory-scale anaerobic mesophilic sewage sludge digestion.

The possibility of the formation of PCDDs and dechlorination of PCDFs during the anaerobic digestion of sewage sludge in laboratory scale digesters was investigated. Digesters were spiked with 1,2,3,4,6,7,8-HpCDF-13C(6) (240 ng/g organic matter (OM)) and pentachlorophenol (PeCP)-13C(6) (24 microg/g OM) and the output sludge monitored for 60 days. No dechlorination or formation of the labelled or native PCDD/Fs was observed.

Quantification of PCDD/F concentrations in animal manure and comparison of the effects of the application of cattle manure and sewage sludge to agricultural land on human exposure to PCDD/Fs.

PCDD/Fs were quantified in samples of cattle, pig, sheep and chicken manure. TEQs ranged from 0.19 ng TEQ/kg dw for the pig manure to 20 ng TEQ/kg dw for one cattle manure sample.

The global re-cycling of persistent organic pollutants is strongly retarded by soils.

'Persistent organic pollutants' (POPs) are semi-volatile, mobile in the environment and bioaccumulate. Their toxicity and propensity for long-range atmospheric transport (LRAT) has led to international bans/restrictions on their use/release. LRAT of POPs may occur by a 'single hop' or repeated temperature-driven air-surface exchange.

Role for non-homologous end-joining in the repair of UVA-induced DNA damage.

Purpose: The biological significance of long-wavelength ultraviolet (UV) light, UVA, is increasingly realized, but the precise nature of the cellular damage responsible for the effects of this radiation is still not clear. It has been reported that UVA can induce double-strand breaks in DNA, but the biological significance of these is not known. We have therefore examined the UVA sensitivity of a cell line deficient in non-homologous end-joining, the major pathway for the repair of DNA double-strand breaks in mammalian cells in order to determine the biological importance of UVA-induced DSB.

The green tea polyphenol, epigallocatechin-3-gallate, protects against the oxidative cellular and genotoxic damage of UVA radiation.

A number of biological activities have been ascribed to the major green tea polyphenol epigallocatechin-3-gallate (EGCG) to explain its chemopreventive properties. Its antioxidant properties emerge as a potentially important mode of action. We have examined the effect of EGCG treatment on the damaging oxidative effects of UVA radiation in a human keratinocyte line (HaCaT).

Investigation into the importance of the stomatal pathway in the exchange of PCBs between air and plants.

The transfer of persistent organic pollutants (POPs) from air to vegetation is an important air-surface exchange process that affects global cycling and can result in human and wildlife exposure via the terrestrial food chain. To improve understanding of this process, the role of stomata in uptake of gas-phase polychlorinated biphenyls (PCBs) was investigated using Hemerocallis x hybrida "Black Eyed Stella", a plant with a high stomatal density. Uptake of PCBs was monitored over a 72-h period in the presence and absence of light.

Air-side and plant-side resistances influence the uptake of airborne PCBs by evergreen plants.

The transfer of persistent organic pollutants (POPs) from airto vegetation is an important air-surface exchange process that affects global cycling and can result in human and wildlife exposure via the terrestrial food chain. To improve understanding of this process, the uptake of gas-phase polychlorinated biphenyls (PCBs) by two slow-growing evergreen shrubs, Skimmia japonicaThunb. and Hebe"Great Orme", was studied to investigate the influence of air-side and plant-side resistances.

The adaptation of two similar soils to pyrene catabolism.

The development of pyrene catabolic activity was assessed in two similar soils (pasture and woodland) amended with 100 mg pyrene kg(-1) In the pasture and woodland soils, significant mineralisation of 14C-pyrene was observed after 8 and 76 weeks soil-pyrene contact times, respectively. In both soils, there were significant decreases (P<0.05) in the lag times and significant increases (P <0.

Temporal and spatial trends of PCB congeners in UK gannet eggs.

Gannet (Sula bassana) eggs collected from Ailsa Craig, Western Scotland between 1977-1998 have been analyzed retrospectively for several PCB congeners. Concentrations of a range of congeners were determined in 8-10 eggs analyzed separately for several individual years. All congeners declined in concentrations throughout the time period, but the rates of decline differed for different congeners.

Polychlorinated dibenzo-p-dioxin and furan (PCDD/F) uptake by pasture.

Uptake of airborne PCDD/Fs by a native pasture sward was studied. The concentrations of the less chlorinated PCDD/Fs (up to and including the Cl5DD/Fs) in pasture harvested on the same day after 2, 6, and 12 weeks exposure were the same, implying that air-pasture steady-state was reached within 2 weeks of exposure. The implications of these observations for the relative importance of input (atmospheric deposition, soil resuspension) and loss (photolysis, degradation, volatilization, cuticular shedding, and growth dilution) processes are discussed and inferences made about the controlling factors.

A dynamic level IV multimedia environmental model: application to the fate of polychlorinated biphenyls in the United Kingdom over a 60-year period.

A dynamic or level IV multimedia model is described and illustrated by application to the fate of three polychlorinated biphenyl (PCB) congeners in the United Kingdom over a 60-year period from their introduction into commerce until the present. Models of this type are shown to be valuable for elucidating the time response of environmental systems to increasing, decreasing, or pulse inputs. The suggestion is made that in addition to the outputs of time-dependent concentrations (which can be compared with monitoring data for validation purposes), it is useful to examine masses, fugacities, and fugacity ratios between media? The relative importance of processes is best evaluated by compiling cumulative intermedia fluxes and quantities lost by reaction and advection and examining the corresponding process rate constants or their reciprocals, the characteristic times.

Performance characteristics and applications of a proton transfer reaction-mass spectrometer for measuring volatile organic compounds in ambient air.

Data illustrating the performance characteristics of a proton transfer reaction-mass spectrometer (PTR-MS) under both laboratory and field conditions are presented. Under laboratory conditions, we demonstrate that PTR-MS measures (within 10%) a 2.6 ppbv concentration of gaseous dimethyl sulfide.

Induction of PAH-catabolism in mushroom compost and its use in the biodegradation of soil-associated phenanthrene.

This paper describes the induction of phenanthrene-catabolism within Phase II mushroom compost resulting from its incubation with (1) phenanthrene, and (2) PAH-contaminated soil. Respirometers measuring mineralization of freshly added 14C-9-phenanthere were used to evaluate induction of phenanthrene-catabolism. Where pure phenanthrene (spiked at a concentration of 400 mg kg(-1) wet wt.

The nature of the acetylcholine and 5-hydroxytryptamine receptors in buccal smooth muscle of the pest slug Deroceras reticulatum.

The characteristics of the acetylcholine (ACh) and 5-hydroxytryptamine (5-HT) receptors of Deroceras buccal muscle were examined using specific pharmacological probes and sucrose gap electrophysiological analysis. ACh induced concentration-dependent smooth tonic contractures coupled with considerable depolarisation from the normal resting membrane potential of -30.6 mV.

Calcium signalling in stomatal responses to pollutants.

Stomatal responses to air pollutants are complex, varying among species and with concentration, environmental conditions and age. In general, short-term exposure to sulphur dioxide (SO ) promotes stomatal opening, whereas longer-term exposure can cause partial stomatal closure. By contrast, the effects of oxides of nitrogen (NO ) are often small or insignificant.