Uptake Of Persistent Organic Pollutants Research Articles

Foliar uptake of persistent organic pollutants at alpine treeline

Previous studies highlighted the role of temperature on the foliar uptake of persistent organic pollutants (POPs) based on their physicochemical properties. However, few studies have focused on the indirect impacts of low temperature on the foliar uptake of POPs due to the changed physiology of leaves. We measured the concentrations and temporal variations of foliar POPs at the treeline on the Tibetan Plateau, the highest-altitudinal treeline on Earth. The leaves at the treeline showed high uptake efficiencies and reservoir capacity of dichlorodiphenyltrichloroethanes (DDTs), which were two times to one order of magnitude higher than those in forests worldwide. Enhanced surface adsorption due to the increased thickness of the wax layer in a colder climate was found to be the primary contributor (>60 %) to the high uptake of DDTs at the treeline, and slow penetration controlled by temperature contributed 13 %−40 %. The relative humidity, related negatively to temperature, also influenced the uptake rates of DDTs by foliage at the treeline (contribution: <10 %). The uptake rates of small molecular-weight POPs (hexachlorobenzene and hexachlorocyclohexanes) by foliage at the treeline were quite lower than those of DDTs, relating probably with the weak penetration of these compounds into leaves and/or low-temperature-induced precipitation washout from leaf surface.

Factors regulating the differential uptake of persistent organic pollutants in cucurbits and non-cucurbits

Contamination with persistent organic pollutants (POPs) has become a worldwide concern owing to their the toxicity to humans and wildlife. Pumpkin, cucumber, and squash (Cucurbitaceae) accumulate POPs in their shoots in concentrations higher than those in non-cucurbits; to elucidate the underlying molecular mechanisms of this accumulation, POP transporters were analyzed in the xylem sap of cucurbits and non-cucurbits. The 17-kDa xylem sap proteins detected in all cucurbits but not in non-cucurbits readily bound polychlorinated biphenyl (PCB) in all tested cucurbits, except in cucumber and loofah, and to dieldrin in all tested cucurbits. Ten genes encoding major latex-like proteins (MLPs) responsible for the accumulation of PCBs in zucchini plants were cloned from cucurbits. Phylogenetic analysis using MLP sequences identified two separate clades, one containing Cucurbitaceae MLPs and the other containing those of non-cucurbit members. Recombinant MLPs bound PCB and dieldrin. Western blotting with anti-MLP antibodies identified translocatable and non-translocatable MLPs between root and stem xylem vessels. Translocation of MLPs from the root to stem xylem vessels and POP-binding ability of MLPs are important for selective accumulation of MLPs in cucurbits. This study provides basic knowledge about phytoremediation through overexpression of MLP genes and for breeding cucurbits that accumulate less contaminants.

Manure amendment reduced plant uptake and enhanced rhizodegradation of 2,2′,4, 4′-tetrabrominated diphenyl ether in soil

To test whether manure amendment in soil reduces plant uptake of persistent organic pollutants, carrot (Daucus carota L.) was used as a model plant and 2,2′,4,4′-tetrabrominated diphenyl ether (BDE-47) was selected as a model persistent organic pollutant to conduct a pot experiment with contaminated soil amended by composted pig manure. The results showed that the concentration and bioconcentration factors (BCFs) of BDE-47 in the edible part of carrot significantly decreased from 229.7 ± 28.2 to 43.4 ± 20.4 ng g−1 and from 1.86 ± 0.5 to 0.15 ± 0.03, respectively, with increasing composted pig manure dose from 0 to 4%. Organic matter (OM) derived from composted pig manure played a dominant role in reducing persistent organic pollutant bioavailability in soil. Composted pig manure amendment and carrot cultivation jointly altered the bacterial community composition in soil, especially the rhizosphere. Rhizodegradation of BDE-47 was enhanced from 8.6 to 28.5% with increasing composted pig manure dose from 0 to 4%, corresponding to increased soil microbe diversity and polybrominated diphenyl ether-degrading bacteria (Sphingomonas, etc.) abundance in the rhizosphere. This study is the first, to the best of our knowledge, to provide an effective agronomic strategy of manure amendment to reduce plant uptake and simultaneously enhance rhizodegradation of persistent organic pollutants in soil, and thus potentially reduce human health risks through dietary intake.

Pollutant and Soil Types Influence Effectiveness of Soil-Applied Absorbents in Reducing Rice Plant Uptake of Persistent Organic Pollutants

Persistent organic pollutants (POPs) in soils are an environmental concern due to their long-term bioavailability, which could be reduced by adding adsorbents. However, testing of these adsorbents is necessary prior to widespread field application. The effects of three adsorbents, nano-organic montmorillonite, nano-organic silicon dioxide (SiO2), and activated carbon, on hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) accumulation in rice (Oryza sativa L.) plants were tested in a greenhouse experiment using two soils, a Hydragric Acrisol (Ac) and a Gleyi-Stagnic Anthrosol (An). The bioconcentration factors (BCFs) of HCB and PeCB to rice roots were 2.3–3.7 and 2.0–3.0 times those to rice shoots, respectively. The applications of the three adsorbents decreased HCB and PeCB extractability in Ac, while only the application of activated carbon decreased their extractability in An. The bioavailability of HCB and PeCB to rice plants in Ac was higher than that in An. In Ac, the applications of nano-organic SiO2 and activated carbon decreased the BCF of HCB to rice roots by 16.1% and 26.8%, respectively, whereas only the application of activated carbon decreased the BCF of PeCB to rice roots by 31.4%, compared to the control. In An, only the application of activated carbon decreased the BCFs of HCB and PeCB to rice roots by 22.9% and 18.2%, respectively, compared to the control. However, the application of nano-organic montmorillonite inhibited rice growth in both soils. The results of this study suggested that the effectiveness of adsorbents would vary with pollutant and soil types, providing a reference point for developing efficient adsorbents to reduce the ecological risk of POPs.

Research progress in uptake of persistent organic pollutants by plants

Plants can absorb persistent organic pollutants(POPs) from air and soil. Roots sorption is one of uptake processes,while evidence showed that POPs absorbed by roots was hardly transferred to the aerial tissues of the plant. The POPs re-volatilized from soil may only influence the parts of plants near the surface of the ground. Compared to the absorption from soil,the absorption of atmospheric POPs by foliage raised more concern. The airborne POPs can be accumulated by plant leaves by wet and dry deposition,which is the main pathway of the atmospheric POPs entering the aerial parts of plants. Air-plant exchange equilibrium is an important state that determines the direction of gas exchange between air and plant. The airborne POPs partition onto plant and approach plant gas-phase equilibrium rather rapidly,within less than 6 days of exposure. Besides exposure time,other environmental factors(temperature,wind speed,humidity,etc.) and the shape,areas and life time of the leaves have impacts on the air-plant exchange equilibrium of POPs. Through the air-plant exchange the airborne POPs were fixed by the plants and finally transferred into soil by falling off the leaves. Therefore,the air-plant exchange of POPs will influence the long-range atmospheric transport and the regional,even global distribution of POPs. Plants such as lichens,mosses,grass and forest have been used as passive samplers to monitor the levels of atmospheric POPs on different time scales and reflect the spatial distribution of POPs. Lichens and mosses are extensively used in environmental pollution studies especially in the polar region,since their collection is relatively easy. For grass,different species have the same ability to absorb the airborne POPs,which was used as bio-monitor to compare the POPs in different regions over the world. Numerous studies indicated that plants act as a "sink" for global cycling of POPs. The POPs absorbed by plants will enter the terrestrial food chains through the consumption of plants by animals and will be transported from one trophic level to a higher one,which will result in bio-concentration and even pose potential threat to the health of humans. However,there are a few studies focusing on the bio-concentration of POPs in the terrestrial food chains currently and most of them utilize models to simulate the bio-concentration process. In this paper,the research progress on the accumulation of POPs by plants including the ways of POPs entering the plants and the air-plant exchange of the airborne POPs were reviewed; the advantage and disadvantage of vegetation passive samplers(lichens,mosses and grass) were discussed. We also pointed out the problems needed to be solved in further studies.

Fate and plant uptake of persistent organic pollutants in soil

Many persistent organic pollutants (POPs), notably hexachlorocyclohexanes (HCHs), chlorinated cyclodienes, and dichlorodiphenyltrichloroethanes (DDTs), remain in Japanese farming soils, more than 40 years after their use as insecticides was prohibited. In recent years, residues of chlorinated cyclodienes in cucurbit fruits have become a problem. But, though HCHs and DDTs have been staying in the soil, residues of these chemicals in crops have not been a problem. So we compared the fates of HCHs (α-, β-, γ-HCHs), chlorinated cyclodienes (dieldrin, endrin, heptachlor exo-epoxide), and DDTs (DDE, dichlorodiphenyldichloroethylene; DDD, dichlorodiphenyldichloroethane) in soil and investigated their uptake by several non-cucurbits and cucurbits. As for the fate of POPs in soil, not only the total concentrations but also the concentrations in soil solution as bioavailable POPs were determined. The half-lives of total β-HCH and DDTs in soil were the longest, and α- and γ-HCHs the shortest. On the other hand, the half-lives of bioavailable POPs ranged from 1/3 to 1/20 of those of total POPs. The ratio of the half-lives of bioavailable POPs to those of total POPs decreased in the order of HCHs > chlorinated cyclodienes > DDTs. Because hydrophobic chemicals were adsorbed strongly to the soil, the bioavailable POPs in soil are controlled by their hydrophobicity, indicated by the values of log K OW (K OW: n-octanol-water partition coefficient). The shoot concentrations of chlorinated cyclodienes and DDTs were higher in cucurbits than in non-cucurbits. However, among POP insecticides, HCHs did not show clear differences. As for the root concentrations, all tested POPs were higher in cucurbits than in non-cucurbits. Through the determination of POPs in soil solution, we could compare the abilities of plants to take up the chemicals using soil solution bioconcentration factors (BCFSS). The values of BCFSS increased with the magnitude of log K OW, in the order of HCHs < chlorinated cyclodienes < DDTs. In addition, BCFSS did not show marked differences among isomers or chemicals with similar structure. Therefore, plant uptake ability was influenced mainly by log K OW. After being applied to agricultural land, α- and γ-HCHs seemed to disappear quickly, β-HCH persisted longer but the uptake in roots was low because of the low log K OW, and DDTs also persisted longer but the bioavailability decreased rapidly in the soil because of their high log K OW. Chlorinated cyclodienes have remained in the soil and have remained available, because they are less likely than HCHs (except β-HCH) to disappear and less likely than DDTs to become adsorbed to the soil. In addition, their higher log K OW than that of HCHs makes them more easily taken up by roots. However, shoot concentrations were high only in cucurbits, for which they remain a problem in Japan.

Modeling the BCF of persistent organic pollutants

The uptake of persistent organic pollutants (POPs) from soil by plants allows the development of phytoremediation protocols to rehabilitate contaminated areas. In this study theoretical descriptors have been employed as independent variables for developing quantitative structure-activity relationship (QSAR) models for predicting the bioconcentration factors (BCFs) of POPs in different plants. A quantitative estimation has been given on the molecular properties of POPs in terms of theoretical molecular descriptors that are relevant to the uptake from soil and pharmacokinetic behavior in plants. The study resulted in statistically significant linear regression models developed for the BCF values of 20 polychlorinated dibenzo-p-dioxins/dibenzofurans and 14 polyhalogenated biphenyls in two zucchini varieties based on retrospective data. The parameters have been selected from a set of 1660 DRAGON, 150 VolSurf and 11 Quantum Chemical descriptors. The best regression model (Eq. 1), employing VolSurf, DRAGON GETA...

The uptake of persistent organic pollutants by plants

Abstract In a field experiment, the transfer of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from contaminated soil to maize (Zea mays L.), sunflower (Helianthus annuus), poplar (Populus nigra × P. maximowiczii) and willow (Salix × smithiana) and the distribution of PCB congeners in maize and sunflower was investigated. The former waste incinerator in Hradec Králové (Czech Republic) was chosen for the experiment. Results of plot screening showed heterogenous contamination by PCBs and PAHs. PCB soil contamination was evidently caused by Delor 106 or Aroclor 1260 stocking and PAH contamination by chemicals containing fluoranthene, benzo/b/fluoranthene, phenanthrene and pyrene. Tested plants were planted on a contaminated field site, in soil contaminated with 1530 µg/kg of total PCBs and 0.138 and 3.42 mg/kg of total PAHs. The results show that maize and sunflower roots accumulated the most PCBs from soil. These plants accumulated hexa- and heptachlorobiphenyl congeners more than tri-, tetra-, and pentachlorobiphenyl congeners. Total concentrations of PAHs in tested plants ranged from 0.096 to 1.34 mg/kg. The highest phenanthrene concentration was found in aboveground biomass of sunflower and the highest concentration of pyrene, in maize roots.

Theoretical Molecular Descriptors Relevant to the Uptake of Persistent Organic Pollutants from Soil by Zucchini. A QSAR Study

The uptake of persistent organic pollutants (POPs) from soil by plants allows the development of phytoremediation protocols to rehabilitate contaminated areas. The use of diverse theoretical descriptors has been reported in the literature for developing quantitative structure-activity relationship (QSAR) models for predicting the bioconcentration factors (BCFs) of POPs in different plants. In this paper an evaluation is given on the molecular properties of POPs in terms of theoretical molecular descriptors that are relevant to the uptake and accumulation of these persistent pollutants from soil by two zucchini varieties. Statistically significant and predictive linear regression models have been developed for the BCF values of 20 polychlorinated dibenzo-p-dioxins/dibenzofurans and 14 polyhalogenated biphenyls in two zucchini varieties based on retrospective data. The relevant parameters have been selected from a set of 1660 DRAGON, 150 VolSurf, and 11 quantum chemical descriptors. The two most significant regression models, containing VolSurf, DRAGON GETAWAY, and quantum chemical descriptors, displayed the following statistical parameters: (eq 3) n = 27, R(2) = 0.940, q(2) = 0.922, SE = 0.155, F = 392.1; (eq 4) n = 27, R(2) = 0.921, q(2) = 0.898, SE = 0.161, F = 140.4. Predictive capabilities of the equations have been validated by using external validation sets. The QSAR models proposed might contribute to the development of viable soil remediation strategies.

The role of caveolae in endothelial cell dysfunction with a focus on nutrition and environmental toxicants

Complications of vascular diseases, including atherosclerosis, are the number one cause of death in Western societies. Dysfunction of endothelial cells is a critical underlying cause of the pathology of atherosclerosis. Lipid rafts, and especially caveolae, are enriched in endothelial cells, and down-regulation of the caveolin-1 gene may provide protection against the development of atherosclerosis. There is substantial evidence that exposure to environmental pollution is linked to cardiovascular mortality, and that persistent organic pollutants can markedly contribute to endothelial cell dysfunction and an increase in vascular inflammation. Nutrition can modulate the toxicity of environmental pollutants, and evidence suggests that these affect health and disease outcome associated with chemical insults. Because caveolae can provide a regulatory platform for pro-inflammatory signalling associated with vascular diseases such as atherosclerosis, we suggest a link between atherogenic risk and functional changes of caveolae by environmental factors such as dietary lipids and organic pollutants. For example, we have evidence that endothelial caveolae play a role in uptake of persistent organic pollutants, an event associated with subsequent production of inflammatory mediators. Functional properties of caveolae can be modulated by nutrition, such as dietary lipids (e.g. fatty acids) and plant-derived polyphenols (e.g. flavonoids), which change activation of caveolae-associated signalling proteins. The following review will focus on caveolae providing a platform for pro-inflammatory signalling, and the role of caveolae in endothelial cell functional changes associated with environmental mediators such as nutrients and toxicants, which are known to modulate the pathology of vascular diseases.

Uptake of Persistent Organic Pollutants by Vegetables Grown in Contaminated Soil in Cluj District, Romania

ISEE-0540 Background and Objectives: Persistent organic pollutants (POPs) such as PAHs and organochlorinated compounds are chemical substances that persist in the environment due to their physical and chemical properties. Unfortunately they could be bioaccumulated through the food web posing a risk for human health. The aim of this study was to determine whether POPs present in contaminated soils along Somes river, are transferred to edible parts of basic vegetables for human or domestic animal consumes such as maize, wheat and potato. From this reasons five agricultural sites and seven private gardens were monitored during the study. Methods: Several water, soil and vegetables samples were collected from different agricultural sites near Somes river between the periods of March 2007-March 2009. The analyses of POPs included sixteen PAH compounds and twenty chlorinated POPs were performed on GC-MS and GC-ECD-FID using Soxhlet and LLE extraction. A simulation experiments was conducted to determine the residual levels and bioaccumulation of most founded POPs compounds on maize and potato. Results: Higher values or POPs were found in soil samples than in river water samples (below with 35% for PAHs and 47% for chlorinated POPs). The concentrations of this POPs were lover in vegetables samples (with 62% for chlorinated POPs and 75% for PAHs) than in corresponding soil samples. Based on simulation experiment considerable concentration of PAHs was measured in leafs, fact that could be attributed to possible air pollution. Conclusions: POPs concentration intake by the selected vegetables was lower than concentration from corresponding soils, higher values of this pollutants were found in roots and leafs excepting the potato where in tubers the concentration were higher than in leaf or roots. The bioconcentration factors values based on dry weight were below 1.2 and in some POPs cases that values decreased with increasing concentrations in soil.

Further studies on the uptake of persistent organic pollutants (POPs) by polyurethane foam disk passive air samplers

Passive air samplers (PAS) can be used to monitor semi-volatile organic compounds in the atmosphere. Polyurethane foam (PUF) disks are a popular sampling medium because they have a high retention capacity for such compounds. This paper reports a highly time-resolved uptake study, to derive uptake rate data under field conditions, and investigate the effects of using different foam densities on the uptake rate. PUF disks were deployed alongside an active sampler, for periods of up to 12 weeks. The uptake rates were measured for a range of gas- and particle-bound persistent organic pollutants (polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs)), of different properties, to explore whether gas–particle partitioning affected uptake rate. Uptake rates for two different densities of foam (0.021 and 0.035 g cm −3) were not statistically significantly different from each other. Uptake rates of light PCBs averaged ∼6.5 m 3 day −1, somewhat higher than in previous studies; higher wind speeds and lower temperatures in this study are the likely reason for this difference. The study showed: i) the uptake rate of the compound with lowest K OA considered in this study (PCB-28/31) declined in the later weeks, indicating an approach to equilibrium; ii) uptake rates of lighter BDEs and heavier PCBs (compounds of intermediate K OA in this study) remain similar throughout the study period, indicating that they are not approaching equilibrium during the 12-week-study; iii) uptake rates were typically: ∼8 m 3 day −1 for PCB-52; ∼9.5 m 3 day −1 for PCB-95; ∼11 m 3 day −1 for BDE-28 and ∼2 m 3 day −1 BDE-99. The latter compound has an important particle-bound component and this lowers the sampling rate compared to predicted uptake rates for compounds which are in the gas phase only. It is shown that knowledge of gas–particle partitioning is needed to correct for this effect, and to improve predicted uptake rates.

Uptake and bioavailability of persistent organic pollutants by plants grown in contaminated soil.

This paper assesses the uptake of persistent organic pollutants (POP's) into plants. In particular, uptake of alpha-endosulfan, beta-endosulfan and endosulfan sulfate from lettuce. The lettuce plants were grown on compost that had previously been contaminated at 10 and 50 microg g(-1) per POP. The soil was slurry spiked by adding the appropriate amount of POP in acetone in an approximate ratio of 1 ratio 2, w/v soil ratio solvent. The solvent was left to evaporate at ambient temperature for 24 hours. Lettuce plants were grown under artificial daylight for 12 hours a day. The influence of soil ageing on the recovery of POP's from spiked soil samples was also assessed. The average recovery of endosulfan compounds from slurry spiked soil (10, 20 and 40 microg g(-1)) was consistent (92.9 +/- 4.4% for n= 9). However, ageing of endosulfan compounds on the slurry spiked soil resulted in lower recoveries (average losses were 12.5% after 14 days ageing of slurry spiked soil). The uptake of POP's was assessed by measuring the amount of endosulfan compounds in roots and leaves from lettuce plants after 10, 20 and 33 days. In addition, control plants grown in uncontaminated soil were monitored and analysed. It was found that endosulfan compounds were present in the roots of all lettuce plants irrespective of soil spike level or age of plant. In the 33 day lettuce plants where the soil was spiked at the highest level (50 microg g(-1)) endosulfan compounds were determined in the leaves. The root to leaf ratio was found to be 3.1 for alpha-endosulfan, 46.0 for beta-endosulfan, and 24.3 for endosulfan sulfate. Spiked lettuce samples were subjected to in vitro gastrointestinal extraction to assess the bioavailability of endosulfan compounds. No detectable endosulfan compounds were determined in the gastric extracts while small quantities (range 0.06-0.12 microg g(-1)) were found in the intestinal extraction. All samples (soil and lettuce) were extracted using pressurised fluid extraction and analysed using gas chromatography with mass selective detection.

Development and Calibration of a Resin-Based Passive Sampling System for Monitoring Persistent Organic Pollutants in the Atmosphere

Responding to a growing need for inexpensive and simple monitoring of persistent organic pollutants (POPs) in the atmosphere, a passive air sampling technique based on the sorption of gaseous pollutants to the sampling resin XAD-2, a styrene−divinylbenzene copolymer, has been developed. A quantitative understanding of the uptake kinetics of the passive air samplers (PAS) was obtained through a combination of field calibration studies, controlled wind tunnel experiments, and flow field simulations. Forty-two PAS were deployed for varying time periods up to 1 yr at three calibration stations in the Laurentian Great Lakes region and the Canadian High Arctic with ongoing conventional air sampling of organochlorine pesticides. The PAS take up quantifiable levels of POPs within a few weeks of deployment, and the amount of chemical collected increases steadily over a 1-yr sampling period. The uptake of POPs by the PAS is controlled by molecular diffusion and independent of wind velocity. The time-averaged air concentrations of organochlorine pesticides derived from the PAS data are comparable with those from HiVol sampling. This study suggests that the XAD-2 resin-based PAS can be used to derive at least semiquantitative information on the vapor-phase concentrations of POPs in the atmosphere and are suitable for the measurements of long-term average concentrations at the levels occurring in remote regions.

Persistent Organic Pollutants (POPs) in Pelagic Systems

Abstract Several studies show that there are interactive processes between eutrophication and uptake of persistent organic pollutants (POPs) in aquatic biota. The main concept is that the increased biomass and production in aquatic ecosystems, due to excess discharge of nutrients, causes a chain event that results in reduced uptake of POPs in primary producers (phytoplankton). This effect is then transferred to consumers at different trophic levels. The chain event may work in an indirect way by increasing the sedimentation of organic matter and, thereby, increasing the downward flux of pollutants to the bottoms, where they are caught in the organic sediment matrix. The chain event may also work in a direct way; the uptake of POPs in the fast growing phytoplankton is decreased as a result of “growth-dilution”, and lower amounts of pollutants are transported in the food-web. The effect seen may also be a result of changed food-web structures that differ considerably from nutrient-poor to nutrient-rich ecos...

Coupling of Phytoplankton Uptake and Air−Water Exchange of Persistent Organic Pollutants

A dynamic model that couples air−water exchange and phytoplankton uptake of persistent organic pollutants has been developed and then applied to PCB data from a small experimental lake. A sensitivity analysis of the model, taking into account the influence of physical environmental conditions such as temperature, wind speed, and mixing depth as well as plankton-related parameters such as biomass and growth rate was carried out for a number of PCBs with different physical−chemical properties. The results indicate that air−water exchange dynamics are influenced not only by physical parameters but also by phytoplankton biomass and growth rate. New phytoplankton production results in substantially longer times to reach equilibrium. Phytoplankton uptake-induced depletion of the dissolved phase concentration maintains air and water phases out of equilibrium. Furthermore, PCBs in phytoplankton also take longer times to reach equilibrium with the dissolved water phase when the latter is supported by diffusive air−water exchange. However, both model analysis and model application to the Experimental Lakes Area of northwestern Ontario (Canada) suggest that the gas phase supports the concentrations of persistent organic pollutants, such as PCBs, in atmospherically driven aquatic environments.

Atmospheric fluxes of persistent semivolatile organic pollutants to a forest ecological system at the Swedish west coast and accumulation in spruce needles

Measurements of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) have been carried out in a forested area at Lake Gårdsjön. The overall aim of this study was to identify the importance of atmospheric fluxes for the occurrence of persistent semivolatile organic compounds in a forest at the Swedish west coast and to measure the major pathways of circulation and accumulation of these contaminants within a terrestrial ecosystem. The sampling was undertaken in campaigns chosen to represent different seasons. The measurements carried out in 1991–94 were concentrated on the uptake of persistent organic pollutants (POPs) in spruce needles in relation to concentrations in air and amounts in deposition, while the measurements undertaken in 1995 also included sampling of throughfall, litterfall and run-off. The concentrations of PCBs and PAHs in the different compartments have been used to identify important reservoirs and to estimate the annual fluxes of these compounds. The results of measurements showed that atmospheric fluxes are important for the occurrence of PCBs and PAHs in forest at the Swedish west coast. A seasonal variation was found in the atmospheric concentrations, and the ambient temperature was important for PCBs in air. The amounts of PAHs and PCBs deposited to the Gårdsjö area (open field) were similar to those obtained during measurements at coastal- and sea-based sites at the Swedish west coast. Soot episodes at the Swedish west coast affected the deposition fluxes of POPs in the forest. There seemed to be both an accumulation and release of POPs in different compartments in this forest ecosystem. A greater deposition of POPs was found in the forest soil via throughfall compared with the open field deposition. An estimate of the fluxes of PAHs and PCBs in the catchment area in a forest showed that the soil is the main reservoir for POPs in this area.