A worldwide survey of polychlorinated dibenzo-p-dioxins, dibenzofurans, and related contaminants in butter

The main source of human exposure to persistent organic pollutants (POPs) is, in general, food. In this study, 64 butter samples from 37 countries were analyzed to assess the global contamination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), hexachlorobenzene (HCB), and 2,2-bis (4-chlorophenyl)-1,1,1-trichloroethane (DDT) together with its major metabolites. The objectives of the study were to assess the presence of major organohalogen contaminants in butter, to trace geographical differences, and to determine toxic equivalents (TEQs) of PCDDs/Fs and dioxin-like PCBs in butter. The highest PCDD/F concentrations were found in butter from Korea with an average of 1.4 pg TEQ g(-1) lipid weight (l.w.). from PCDD/F and an additional contribution from the non- and mono-ortho-PCBs of 0.55 pg TEQ g(-1) l.w. Belgian butter showed average levels of 0.53 and 1.2 pg TEQ g(-1) l.w. for PCDDs/Fs and PCBs, respectively, but one sample of Belgium butter had a total TEQ level as high as 4.0 pg TEQ g(-1) l.w. Three out of five butter samples from Portugal showed similarly high PCDD/F TEQ levels. The sigmaPCB levels in European butter appeared to be somewhat higher than in the samples from the rest of the world. The average contribution of CB-153 to the total PCB concentration was 22% (SD 6.4, coefficient of variation 29%). Generally, the PCBs contributed around 60% of the total TEQ value, with CB-126 contributing approximately half of this value. This shows the important TEQ contribution from dioxinlike PCBs to the total TEQs. The highest HCB levels were found in butter samples from Russia, Ukraine, Belgium, and Slovenia. Low levels of HCB in butter were generally found in the Southern Hemisphere. Butter samples from countries from Eastern Europe had elevated sigmaDDT concentrations, with a particularly high concentration in Ukraine butter, followed by some Russian samples, Brazil, and the U.S.     

Flux of organic compounds from grass measured by relaxed eddy accumulation technique

Fluxes of some Volatile Organic Compounds (VOC) from grass were measured at a golf course in western Sweden, using the Relaxed Eddy Accumulation (REA) technique. The sampling was done by collecting VOC onto adsorbent tubes and the analysis was performed by thermal desorption followed by GC/MS. High emissions were observed after cutting. Transient fluxes of (Z)-3-hexenyl acetate (0.51 microg m(-2) s(-1)), (Z)-3-hexen-1-ol (0.14 microg m(-2) s(-1)) and (Z)-3-hexenal (0.40 microg m(-2) s(-1)) were measured, even at low temperatures. The REA technique requires a relatively large fetch area that is sometimes not available. Therefore, a procedure for correcting measured fluxes from a limited fetch is suggested.     

A comparison of three models of 137Cs transfer in forest ecosystems.

The predictions of three models of 137Cs transfer in forest ecosystems (FOA, LOGNAT and FORESTLAND) were compared. The scenario for the model-model comparison consisted of an acute dry deposition of 137Cs over a coniferous forest. The model predictions were subsequently compared (model-data comparison) with values derived from experimental data measured in forests of the Bryansk region in Russia that were contaminated by the Chernobyl accident and that have similar characteristics to the forests described in the scenario. The predictions of radiocaesium levels in the litter-soil layer, berries, needles, wood, whole tree and moose made with the models were in relatively good agreement with each other (within a factor of 1.4-2.9). The best agreement was observed for berries and moose and the worst for wood. There was also good agreement between the model predictions for the same variables and the experimental data (within a factor of 1.2 3.2). In this case, the best agreement was observed for the litter-soil layer and the worst for wood and the whole tree. Overall, at least for the studied scenario and for the first 10 years after deposition, any of the models can be used if the final aim is to estimate average concentrations in different forest components. The agreement between the model predictions worsens with time and there were differences in the form of the time dependencies predicted by the models, especially for wood. This may lead to larger differences between the model predictions and the experimental data for times beyond the period for which data were available for comparison (10 years after the deposition).     

CALIBRATION OF STORM LOADS IN THE SOUTH PRONG WATERSHED,FLORIDA, USING BASINS/HSPF1

ABSTRACT: The South Prong watershed is a major tributary system of the Sebastian River and adjacent Indian River Lagoon. Continued urbanization of the Sebastian River drainage basin and other watersheds of the Indian River Lagoon is expected to increase runoff and nonpoint source pollutant loads. The St. Johns River Water Management District developed watershed simulation models to estimate potential impacts on the ecological systems of receiving waters and to assist planners in devising strategies to prevent further degradation of water resources. In the South Prong system, a storm water sampling program was carried out to calibrate the water quality components of the watershed model for total suspended solids (TSS), total phosphorous (TP), and total nitrogen (TN). During the period of May to November 1999, water quality and flow data were collected at three locations within the watershed. Two of the sampling stations were located at the downstream end of major watercourses. The third station was located at the watershed outlet. Five storm events were sampled and measured at each station. Sampling was conducted at appropriate intervals to represent the rising limb, peak, and recession limb of each storm event. The simulations were handled by HSPF (Hydrologic Simulation Program‐Fortran). Results include calibration of the hydrology and calibration of the individual storm loads. The hydrologic calibration was continuous over the period 1994 through 1999. Simulated storm runoff, storm loads, and event mean concentrations were compared with their corresponding observed values. The hydrologic calibration showed good results. The outcome of the individual storm calibrations was mixed. Overall, however, the simulated storm loads agreed reasonably well with measured loads for a majority of the storms.     

ESTIMATING NONPOINT SOURCE POLLUTION LOADS WITH A GIS SCREENING MODEL1

ABSTRACT: The St. Johns River Water Management District (SJR-WMD) is using a Geographic Information System (GIS) screening model to estimate annual nonpoint source pollution loads to surface waters and determine nonpoint source pollution problem areas within the SJRWMD. The model is a significant improvement over current practice because it is contained entirely within the district's GIS software, resulting in greater flexibility and efficiency, and useful visualization capabilities. Model inputs consist of five spatial data layers, runoff coefficients, mean runoff concentrations, and stormwater treatment efficiencies. The spatial data layers are: existing land use, future land use, soils, rainfall, and hydrologic boundaries. These data layers are processed using the analytical capabilities of a cell-based GIS. Model output consists of seven spatial data layers: runoff, total nitrogen, total phosphorous, suspended solids, biochemical oxygen demand, lead, and zinc. Model output can be examined visually or summarized numerically by drainage basin. Results are reported for only one of the SJRWMD's ten major drainage basins, the lower St. Johns River basin. The model was created to serve a major planning effort at the SJRWMD; results are being actively used to address nonpoint source pollution problems.     

Long-term fire frequency not linked to prehistoric occupations in northern Swedish boreal forest

Knowledge of past fire regimes is crucial for understanding the changes in fire frequency that are likely to occur during the coming decades as a result of global warming and land-use change. This is a key issue for the sustainable management of forest biodiversity because fire regimes may be controlled by vegetation, human activities, and/or climate. The present paper aims to reconstruct the pattern of fire frequency over the Holocene at three sites located in the same region in the northern Swedish boreal forest. The fire regime is reconstructed from sedimentary charcoal analysis of small lakes or ponds. This method allows fire events to be characterized, after detrending the charcoal influx series, and allows estimation of the time elapsed between fires. The long-term fire regime, in terms of fire-free intervals, can thus be elucidated. At the three sites, the mean fire-free intervals through the Holocene were long and of similar magnitude (approximately 320 years). This similarity suggests that the ecological processes controlling fire ignition and spread were the same. At the three sites, the intervals were shorter before 8600 cal yr BP (calibrated years before present), between 7500 and 4500 cal yr BP, and after 2500 cal yr BP. Geomorphological and vegetation factors cannot explain the observed change, because the three sites are located in the same large ecological region characterized by Pinus sylvestris-Ericaceae mesic forests, established on morainic deposits at the same elevation. Archaeological chronologies also do not match the fire chronologies. A climatic interpretation is therefore the most likely explanation of the long-term regional pattern of fire. Although recent human activities between the 18th and the 20th centuries have clearly affected the fire regime, the dominant factor controlling it for 10000 years in northern Sweden has probably been climatic.     

Identification and quantification of products formed via photolysis of decabromodiphenyl ether

Background, aim, and scope  Decabromodiphenyl ether (DecaBDE) is used as an additive flame retardant in polymers. It has become a ubiquitous environmental contaminant, particularly abundant in abiotic media, such as sediments, air, and dust, and also present in wildlife and in humans. The main DecaBDE constituent, perbrominated diphenyl ether (BDE-209), is susceptible to transformations as observed in experimental work. This work is aimed at identifying and assessing the relative amounts of products formed after UV irradiation of BDE-209. Materials and methods  BDE-209, dissolved in tetrahydrofuran (THF), methanol, or combinations of methanol/water, was exposed to UV light for 100 or 200 min. Samples were analyzed by gas chromatography/mass spectrometry (electron ionization) for polybrominated diphenyl ethers (PBDEs), dibenzofurans (PBDFs), methoxylated PBDEs, and phenolic PBDE products. Results  The products formed were hexaBDEs to nonaBDEs, monoBDFs to pentaBDFs, and methoxylated tetraBDFs to pentaBDFs. The products found in the fraction containing halogenated phenols were assigned to be pentabromophenol, dihydroxytetrabromobenzene, dihydroxydibromodibenzofuran, dihydroxytribromodibenzofuran, and dihydroxytetrabromodibenzofuran. The PBDEs accounted for approximately 90% of the total amount of substances in each sample and the PBDFs for about 10%. Discussion  BDE-209 is a source of PBDEs primarily present in OctaBDEs but also to some extent in PentaBDEs, both being commercial products now banned within the EU and in several states within the USA. It is notable that OH-PBDFs have not been identified or indicated in any of the photolysis studies performed to date. Formation of OH-PBDFs, however, may occur as pure radical reactions in the atmosphere. Conclusions  Photolysis of decaBDE yields a wide span of products, from nonaBDEs to hydroxylated bromobenzenes. It is evident that irradiation of decaBDE in water and methanol yields OH-PBDFs and MeO-PBDFs, respectively. BDE-202 (2,2′,3,3′,5,5′,6,6′-octabromodiphenyl ether) is identified as a marker of BDE-209 photolysis. Recommendations and perspectives  BDE-209, the main constituent of DecaBDE, is primarily forming debrominated diphenyl ethers with higher persistence which are more bioaccumulative than the starting material when subjected to UV light. Hence, DecaBDE should be considered as a source of these PBDE congeners in the environment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.