Accumulation Rate, Depuration Kinetics, and Tissue Distribution of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans (PCDD/Fs) in Suckler Ewes (Ovis aries).

Understanding the transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in farm animals is essential for ensuring food safety, but such information for suckler ewes (Ovis aries) has been lacking. This work quantifies the accumulation, tissue distribution, and depuration kinetics of PCDD/Fs in these animals. Six suckler ewes (EXP group) were exposed to PCDD/Fs through contaminated hay (2.3-12.7 ng toxic-equivalent kg-1 dry matter) and then allowed to depurate by switching to noncontaminated hay from 29 days of lactation. Four control ewes were fed continuously with noncontaminated hay. At different time points covering depuration, weaning and slaughter, PCDD/F analysis of milk (three time points), blood and sternal adipose tissue (five time points), Longissimus thoracis muscle, liver, and empty body homogenate at slaughter (188 days of depuration) was performed. A relevant PCDD/F bioaccumulation was observed from oral intake in milk and adipose tissue (biotransfer factors of 1.24 and 1.06 day kg-1 lipids for the sum toxic-equivalent, respectively) in the EXP ewes, especially for penta- and hexa-chlorinated congeners. The EXP ewes' adipose tissue started at 10-fold the EU maximum level (ML) and showed depuration below the ML after 130 days. Specific PCDD/F accumulation in the ewe liver was observed, especially for dibenzofurans. These toxicokinetic data can inform recommendations to ensure the chemical safety of sheep food products.

Evolution of chlorinated paraffin and olefin fingerprints in sewage sludge from 1993 to 2020 of a Swiss municipal wastewater treatment plant.

Exposure of humans to chlorinated paraffins (CPs) and chlorinated olefins (COs) can occur via contact with CP-containing plastic materials. Such plastic materials can contain short-chain CPs (SCCPs), which are regulated as persistent organic pollutants (POPs) under the Stockholm Convention since 2017. Municipal wastewater treatment plants (WWTP) collect effluents of thousands of households and their sludge is a marker for CP exposure. We investigated digested sewage sludge collected in the years 1993, 2002, 2007, 2012, and 2020 from a Swiss WWTP serving between 20000 and 23000 inhabitants. A liquid chromatography mass spectrometry (R > 100000) method, in combination with an atmospheric pressure chemical ionization source (LC-APCI-MS), was used to detect mass spectra of CPs and olefinic side products. A R-based automated spectra evaluation routine (RASER) was applied to search for ∼23000 ions whereof ∼6000 ions could be assigned to CPs, chlorinated mono- (COs), di- (CdiOs) and tri-olefins (CtriOs). Up to 230 CP-, 120 CO-, 50 CdiO- and 20 CtriO-homologues could be identified in sludge. Characteristic fingerprints were deduced describing C- and Cl-homologue distributions, chlorine- (nCl) and carbon- (nC) numbers of CPs and COs. In addition, proportions of saturated and unsaturated material were determined together with proportions of different chain length classes including short- (SC), medium- (MC), long- (LC) and very long-chain (vLC) material. A substantial reduction of SCCPs of 84% was observed from 1993 to 2020. Respective levels of MCCPs, LCCPs and vLCCPs decreased by 61, 69 and 58%. These trends confirm that banned SCCPs and non-regulated CPs are present in WWTP sludge and higher-chlorinated SCCPs were replaced by lower chlorinated MCCPs. Combining high-resolution mass spectrometry with a selective and fast data evaluation method can produce characteristic fingerprints of sewage sludge describing the long-term trends in a WWTP catchment area.

Transgenerational mass balance and tissue distribution of PCBs and PCDD/Fs from grass silage and soil into cow-calf continuum.

Grass-based suckling beef-derived foods occasionally exceed regulatory levels for polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). Ensuring chemical safety requires understanding the cow-calf transgenerational PCB and PCDD/F fate. The current focus was on dairy cows, omitting transgenerational fate and suckling beef-related physiological effects. This study aimed to investigate PCB and PCDD/F absorption, distribution, metabolism, and excretion within 12 Simmental cows (six primiparous/six multiparous) and 12 calves fed with the milk of their respective mothers for 109 days prepartum until 288 days in milk (DIM), i.e., slaughter time. Eight cows were exposed to a grass silage-soil mixture. Four were decontaminated after DIM164 by receiving uncontaminated grass silage, which four control cows received. An input-output balance during gestation and lactation was computed from PCB, PCDD/F, and lipid inputs (solid feed/milk intakes), outputs (fecal/milk excretions), and body storage (initial/final burdens). At slaughter, PCB and PCDD/F tissue distribution, and lipid allometry were linked. Apparent PCB and PCDD/F absorption rates and metabolized fractions decreased with increasing chlorination. In calves, PCB absorption showed no effect due to chlorination (steady range: 71-87%). High-chlorinated PCB and PCDD/F absorption rates decreased when provided through soil. Cows excreted PCBs and PCDD/Fs via feces (50% relative to input) and milk (9%) and accumulated only 5% in their body, whereas calves accumulated the largest fraction of the total input in their bodies (44%). Cow physiology affected accumulation and excretion, as in primiparous cows, net body burden and milk assimilation efficiencies were higher and lower, respectively, than in multiparous. Liver-specific enrichment was observed in cows and calves (7.0- and 3.2-fold iPCB and dlPCB + PCDD/F TEQ, compared to empty body-based lipid concentrations), whereas iPCBs were also enriched in kidneys (3.1-fold) and muscles (1.5-fold). Consequently, adipose concentrations did not perfectly represent most edible beef tissues. This highlights the essence of integrating the interplay between physicochemical pollutant properties and animal physiology in transgenerational transfer assessments of PCBs and PCDD/Fs.

Accumulation and decontamination kinetics of PCBs and PCDD/Fs from grass silage and soil in a transgenerational cow-calf setting.

Polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are bioaccumulative pollutants that endanger bovine food safety. Bioaccumulation depends, among others, on the physiological dynamics of the cow's reproductive cycle. However, recent studies have focused only on near steady-state situations. Thus, the effects of animal physiology on PCB + PCDD/F transfer from grass silage and soil to cows' blood, adipose tissue, and milk and subsequently to suckling calves during gestation and lactation were investigated. In the exposed group, nine cows ate a grass silage/contaminated soil mixture (6.6 ± 0.8 µg iPCBs and 2.6 ± 0.4 ng dlPCB + PCDD/F TEQ kgDM-1) for 109 days prepartum until 288 days in milk (DIM). Four of these cows underwent decontamination after DIM164, receiving the same clean grass silage as the four control cows during the experiment. Calves were fed the milk of their respective mothers. In the exposed group, transgenerational bioaccumulation occurred until DIM164, with calf blood and adipose tissue PCB + PCDD/F concentrations reaching levels twice as high as those in their respective mothers. Transfer rates from oral intake to milk ranged from 0.1 up to 42%, depending on pollutant congener, dietary treatment, and reproductive parity of the cow. Congener and parity also influenced the decontamination half-lives of milk. In decontaminated calves, declines in adipose tissue PCB + PCDD/F concentrations coincided with increases in body fat mass. Therefore, it is essential to know the physiological characteristics of cattle, exposure dose and duration, and physicochemical compound properties to perform reliable transfer assessments.

Average transfer factors are not enough: The influence of growing cattle physiology on the transfer rate of polychlorinated biphenyls from feed to adipose.

Food of animal origin accounts for >90% of the overall human exposure to polychlorinated biphenyls (PCBs). Food regulatory maximum levels help to control this exposure, but bovine meat has been found to be prone to exceed those occasionally. In order to ensure the chemical safety of bovine meat, the aim was to explore the dependency of the bioconcentration (BCF) and biotransfer (BTF) factor, and assimilation efficiency (AE) of PCBs on carcass lipid proportion and growth rate of beef cattle. Eleven bulls were fattened for 293 days with three different diets (7.0, 7.4, 7.5 MJ net energy for growth kg-1 dry matter) at PCB background levels, until slaughter at 530 or 600 kg body weight. Feed and perirenal adipose tissue were sampled for PCB analyses via GC/HRMS and carcass lipid proportion was estimated by the 11th rib dissection technique. For all tested PCBs, BCF (ranging from 0.7 to 18.4) and BTF (ranging from 0.1 to 2.7) decreased at least 1.5 up to 10.6-fold when the carcass lipid proportion increased by 4%, resulting from a typical dilution process. For a faster growth rate of 0.18 kg d-1 however, only a non-significant increasing trend in transfer factors (1.1 to 2.1-fold) was seen. Besides, the transfer factors increased with PCB chlorination degree, non-ortho substitution and lipophilicity. These results underpin the complex interaction between animal physiology and PCB physicochemical properties, making it challenging to interpret average transfer factors to support chemical risk assessment and management.

Combined sediment desorption and bioconcentration model to predict levels of dioxin-like chemicals in fish.

Flooding and other sediment disturbances can lead to increases in sediment resuspension. In this context, it is of central importance to understand the kinetics of release from these sediments and the uptake of pollutants, such as polychlorinated biphenyls (PCBs) and polychlorinated dioxins and furans (PCDD/Fs), into aquatic organisms. In the present study, we parameterized a sediment desorption model based on experimentally determined rapidly-desorbing fractions of dioxin-like chemicals (DLCs). We coupled this desorption model with a physiologically-based toxicokinetic model for rainbow trout. This combined model was used to predict DLC concentrations in the muscle of exposed fish. The performance of this model was evaluated using a previously published dataset on DLC uptake from sediment suspensions during simulated re-suspension events. Predictions generally differed less than 10-fold from measured values, and the model showed a good global coefficient of determination (R2) of 0.95. The root mean squared error (RMSE) for PCBs was 0.31 log units and 0.53 log units for PCDD/Fs. The results of our study demonstrate that the prediction of bioconcentration and related risk to fish resulting from sediment resuspension can be accurately predicted using coupled desorption and toxicokinetic models.

Trace-Level Persistent Organic Pollutant Analysis with Gas-Chromatography Orbitrap Mass Spectrometry-Enhanced Performance by Complementary Acquisition and Processing of Time-Domain Data.

The range of commercial techniques for high-resolution gas-chromatography-mass spectrometry (GC-MS) has been recently extended with the introduction of GC Orbitrap Fourier transform mass spectrometry (FTMS). We report on progress with quantitation performance in the analysis of persistent organic pollutants (POP), by averaging of time-domain signals (transients), from a number of GC-FTMS experiment replicates. Compared to a standard GC-FTMS measurement (a single GC-FTMS experiment replicate, mass spectra representation in reduced profile mode), for the 10 GC-FTMS technical replicates of ultratrace POP analysis, sensitivity improvement of up to 1 order of magnitude is demonstrated. The accumulation method was implemented with an external high-performance data acquisition system and dedicated data processing software to acquire the time-domain data for each GC-FTMS replicate and to average the acquired GC-FTMS data sets. Concomitantly, the increased flexibility in ion signal detection allowed the attainment of ultrahigh-mass resolution (UHR), approaching R = 700 000 at m/z = 200.

Dioxins and PCBs in Meat - Still a Matter of Concern?

Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) summarized as dioxins, as well as polychlorinated biphenyls (PCBs) are persistent, bio-accumulative and toxic environmental contaminants. Over 95% of human exposure to these problematic chemicals occurs via the ingestion of fatty rich food like meat and meat products, fatty fish, as well as milk and dairy products. Several major food and feed contamination incidents in Europe during the years 1997 and 2010 revealed the necessity of establishing food and feed monitoring programs for dioxins and PCBs. Various monitoring programs carried out by the Federal Office of Public Health (FOPH) and the Federal Food Safety and Veterinary Office (FSVO), suggest that cattle from extensive farming (suckler cow husbandry) exhibited higher levels of dioxin-like PCBs (dl-PCBs) and exceeded with higher frequency the permitted maximum levels (ML) when compared to conventional raised cattle. The reasons for the higher levels are possibly due to higher levels of PCBs in green fodder (pasture, silage, and hay) when compared to the concentrated feed used in conventional farming. Additionally, an increased uptake of soil, which is known to be a risk matrix for the uptake of dioxins and PCBs in grazing animals, leads to elevated contaminant levels in the suckler cows and hence their calves. Furthermore, PCB point sources present on a farm from older building and construction materials (e.g. PCB-containing wall paints) might result in very high contamination of the animals and the meat produced from them.

Persistent organic pollutants in red- and white-blooded High-Antarctic notothenioid fish from the remote Weddell Sea.

It has been suggested that High-Antarctic waters, despite their remoteness from human activities, are impacted by anthropogenic pollution, and that the local biota are accumulating the contaminants. At present, no data exist on persistent organic pollutant (POP) body burdens for notothenioid fish inhabiting the High-Antarctic Weddell Sea. We determined the pollutant load in white muscle tissue of red- and white-blooded notothenoids from the Weddell Sea (Trematomus loennbergii and Chionodraco hamatus, respectively), and compared them to our previous measurements of POPs in Low-Antarctic notothenioids. Analytes included various organochlorine pesticides (OCPs), polychlorinated biphenyls (indicator (i) PCBs, dioxine-like (dl) PCBs) and polybrominated diphenyl ethers (PBDEs). The analytical concentrations were converted into 2,3,7,8-TCDD toxic equivalents (TEQs). Compared to T. loennbergii, C. hamatus had lower levels of ß-HCH (0.45 vs. 4.5 ng g-1 lipid weight), and Σ iPCBs (30 vs. 39 ng g-1 lipid weight), as well as lower levels of Σ PBDEs (131 vs. 261 ng g-1 fresh weight). POP body burdens and TEQs were mostly similar to those of Low-Antarctic notothenioids analysed previously, and not related to the trophic positions of the species. The variations in POP levels between and within High- and Low-Antarctic notothenioids only marginally corresponded to sampling site, ecological differences or trophic levels of the species, and might rather be related to metabolism or age effects. The present findings suggest that fishes of High-Antarctic waters, although this area is more remote and less influenced by local human activities, do not show lower POP body burdens than fishes from Low-Antarctic waters.

Dynamic Transgenerational Fate of Polychlorinated Biphenyls and Dioxins/Furans in Lactating Cows and Their Offspring.

We report on two farms in Switzerland heavily contaminated by polychlorinated biphenyls (PCBs) and dioxins (PCDD/Fs), occurring in the first case from diffuse sources and in the second case from PCB-containing wall paint. Extensive measurements of PCBs and PCDD/Fs on site (soil, forage, and paint) and in cattle (blood, fat, and milk) allowed validation of our novel dynamic toxicokinetic model, which includes the transfer of contaminants from the mother cows to their suckling calf and the uptake of soil by grazing cattle. We show that for calves, the mother milk is the main uptake route of contaminants. For both cows and calves, ingestion of contaminated soil, although often overlooked, is an appreciable uptake path. The remediation of the contaminated stable lead to a 2-3 fold reduction of the PCB levels in animals within one year. The transfer of animals to an uncontaminated mountain site during summer proved to be an effective decontamination procedure with up to 50% reduction of the levels within three months. Our study calls for a rapid removal of PCB-containing materials in animal husbandry farms and shows that the diffuse contamination of soils will remain a source for PCBs and PCDD/Fs in our food chain for decades to come.

The 2015 Annual Meeting of SETAC German Language Branch in Zurich (7-10 September, 2015): Ecotoxicology and environmental chemistry-from research to application.

This report provides a brief review of the 20th annual meeting of the German Language Branch of the Society of Environmental Toxicology and Chemistry (SETAC GLB) held from September 7th to 10th 2015 at ETH (Swiss Technical University) in Zurich, Switzerland. The event was chaired by Inge Werner, Director of the Swiss Centre for Applied Ecotoxicology (Ecotox Centre) Eawag-EPFL, and organized by a team from Ecotox Centre, Eawag, Federal Office of the Environment, Federal Office of Agriculture, and Mesocosm GmbH (Germany). Over 200 delegates from academia, public agencies and private industry of Germany, Switzerland and Austria attended and discussed the current state of science and its application presented in 75 talks and 83 posters. In addition, three invited keynote speakers provided new insights into scientific knowledge 'brokering', and-as it was the International Year of Soil-the important role of healthy soil ecosystems. Awards were presented to young scientists for best oral and poster presentations, and for best 2014 master and doctoral theses. Program and abstracts of the meeting (mostly in German) are provided as Additional file 1.

A Temperate Alpine Glacier as a Reservoir of Polychlorinated Biphenyls: Model Results of Incorporation, Transport, and Release.

In previous studies, the incorporation of polychlorinated biphenyls (PCBs) has been quantified in the accumulation areas of Alpine glaciers. Here, we introduce a model framework that quantifies mass fluxes of PCBs in glaciers and apply it to the Silvretta glacier (Switzerland). The models include PCB incorporation into the entire surface of the glacier, downhill transport with the flow of the glacier ice, and chemical fate in the glacial lake. The models are run for the years 1900-2100 and validated by comparing modeled and measured PCB concentrations in an ice core, a lake sediment core, and the glacial streamwater. The incorporation and release fluxes, as well as the storage of PCBs in the glacier increase until the 1980s and decrease thereafter. After a temporary increase in the 2000s, the future PCB release and the PCB concentrations in the glacial stream are estimated to be small but persistent throughout the 21st century. This study quantifies all relevant PCB fluxes in and from a temperate Alpine glacier over two centuries, and concludes that Alpine glaciers are a small secondary source of PCBs, but that the aftermath of environmental pollution by persistent and toxic chemicals can endure for decades.

Persistent organic pollutants in tissues of the white-blooded Antarctic fish Champsocephalus gunnari and Chaenocephalus aceratus.

The global occurrence of persistent organic pollutants (POPs) continuously contributes to their accumulation also in remote areas such as the Antarctic Ocean. Antarctic fish, which hold high trophic positions but appear to possess low endogenous elimination rates for chemicals, are expected to bioaccumulate POPs with rising anthropogenic pollution. Using a chemical-analytical method, we measured concentrations of PCBs, PBDEs, HCBs, HCH and DDTs and determined toxic equivalents (TEQs) and bioanalytical equivalents (BEQs) in muscle and ovaries of Antarctic icefish caught in the Southern Ocean around Elephant Island. We used two species with different feeding habits and trophic web positions: the planktivorous Champsocephalus gunnari and the piscivorous Chaenocephalus aceratus. Our results revealed higher contaminant levels in ovary than in muscle tissues of both species. Most analytes concentrations and the TEQs (0.2-0.5) and BEQs (0.2) were lower as in temperate species. Comparison with literature data points to higher PCB (20-22 ng g(-1) lipid weight (lw)) and DDT (7-19.5 ng g(-1) lw) concentrations than those measured in icefish in the 90's. For the other contaminants, we could not identify temporal trends. We found a higher bioaccumulation of contaminants, particularly HCB and DDTs, in C. aceratus (6.2 & 19.5 ng g(-1) lw, respectively) than in C. gunnari (3.8 & 7.0 ng g(-1) lw, respectively). However, there was no general species-specific accumulation pattern of the different toxicant classes between the two icefish. Thus, the expected link between contaminant burdens of C. aceratus and C. gunnari and their ecological traits was only weakly supported for these species.

Tracking SVOCs' Transfer from Products to Indoor Air and Settled Dust with Deuterium-Labeled Substances.

Semivolatile organic compounds (SVOCs) can be released from products and distributed in the indoor environment, including air and dust. However, the mechanisms and the extent of substance transfer into air and dust are not well understood. Therefore, in a small-scale field study the transfer of nine SVOCs was investigated: Four artificial consumer products were doped with eight deuterium-labeled plasticizers (phthalates and adipates) and installed in five homes to investigate the emission processes of evaporation, abrasion, and direct transfer. Intentional release was studied with a commercial spray containing a pyrethroid. During the 12 week study, indoor air and settled dust samples were collected and analyzed. On the basis of our measurement results, we conclude that the octanol-air partitioning coefficient Koa is a major determinant for the substance transfer into either air or dust: A high Koa implies that the substance is more likely to be found in dust than in air. The emission process also plays a role: For spraying, we found higher dust and air concentrations than for evaporation. In contrast, apartment parameters like air exchange rate or temperature had just a minor influence. Another important mechanistic finding was that although transfer from product to dust currently is postulated to be mostly mediated by air, direct transport from product to dust on the product surface was also observed.

Early life exposure to PCB126 results in delayed mortality and growth impairment in the zebrafish larvae.

The occurrence of chronic or delayed toxicity resulting from the exposure to sublethal chemical concentrations is an increasing concern in environmental risk assessment. The Fish Embryo Toxicity (FET) test with zebrafish provides a reliable prediction of acute toxicity in adult fish, but it cannot yet be applied to predict the occurrence of chronic or delayed toxicity. Identification of sublethal FET endpoints that can assist in predicting the occurrence of chronic or delayed toxicity would be advantageous. The present study characterized the occurrence of delayed toxicity in zebrafish larvae following early exposure to PCB126, previously described to cause delayed effects in the common sole. The first aim was to investigate the occurrence and temporal profiles of delayed toxicity during zebrafish larval development and compare them to those previously described for sole to evaluate the suitability of zebrafish as a model fish species for delayed toxicity assessment. The second aim was to examine the correlation between the sublethal endpoints assessed during embryonal and early larval development and the delayed effects observed during later larval development. After exposure to PCB126 (3-3000ng/L) until 5 days post fertilization (dpf), larvae were reared in clean water until 14 or 28 dpf. Mortality and sublethal morphological and behavioural endpoints were recorded daily, and growth was assessed at 28 dpf. Early life exposure to PCB126 caused delayed mortality (300 ng/L and 3000 ng/L) as well as growth impairment and delayed development (100 ng/L) during the clean water period. Effects on swim bladder inflation and cartilaginous tissues within 5 dpf were the most promising for predicting delayed mortality and sublethal effects, such as decreased standard length, delayed metamorphosis, reduced inflation of swim bladder and column malformations. The EC50 value for swim bladder inflation at 5 dpf (169 ng/L) was similar to the LC50 value at 8 dpf (188 and 202 ng/L in two experiments). Interestingly, the patterns of delayed mortality and delayed effects on growth and development were similar between sole and zebrafish. This indicates the comparability of critical developmental stages across divergent fish species such as a cold water marine flatfish and a tropical freshwater cyprinid. Additionally, sublethal effects in early embryo-larval stages were found promising for predicting delayed lethal and sublethal effects of PCB126. Therefore, the proposed method with zebrafish is expected to provide valuable information on delayed mortality and delayed sublethal effects of chemicals and environmental samples that may be extrapolated to other species.

Towards science-based sediment quality standards-Effects of field-collected sediments in rainbow trout (Oncorhynchus mykiss).

Sediments can act as long-term sinks for environmental pollutants. Within the past decades, dioxin-like compounds (DLCs) such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention in the scientific community. To investigate the time- and concentration-dependent uptake of DLCs and PAHs in rainbow trout (Oncorhynchus mykiss) and their associated toxicological effects, we conducted exposure experiments using suspensions of three field-collected sediments from the rivers Rhine and Elbe, which were chosen to represent different contamination levels. Five serial dilutions of contaminated sediments were tested; these originated from the Prossen and Zollelbe sampling sites (both in the river Elbe, Germany) and from Ehrenbreitstein (Rhine, Germany), with lower levels of contamination. Fish were exposed to suspensions of these dilutions under semi-static conditions for 90 days. Analysis of muscle tissue by high resolution gas chromatography and mass spectrometry and of bile liquid by high-performance liquid chromatography showed that particle-bound PCDD/Fs, PCBs and PAHs were readily bioavailable from re-suspended sediments. Uptake of these contaminants and the associated toxicological effects in fish were largely proportional to their sediment concentrations. The changes in the investigated biomarkers closely reflected the different sediment contamination levels: cytochrome P450 1A mRNA expression and 7-ethoxyresorufin-O-deethylase activity in fish livers responded immediately and with high sensitivity, while increased frequencies of micronuclei and other nuclear aberrations, as well as histopathological and gross pathological lesions, were strong indicators of the potential long-term effects of re-suspension events. Our study clearly demonstrates that sediment re-suspension can lead to accumulation of PCDD/Fs and PCBs in fish, resulting in potentially adverse toxicological effects. For a sound risk assessment within the implementation of the European Water Framework Directive and related legislation, we propose a strong emphasis on sediment-bound contaminants in the context of integrated river basin management plans.

Biofuel-Promoted Polychlorinated Dibenzodioxin/furan Formation in an Iron-Catalyzed Diesel Particle Filter.

Iron-catalyzed diesel particle filters (DPFs) are widely used for particle abatement. Active catalyst particles, so-called fuel-borne catalysts (FBCs), are formed in situ, in the engine, when combusting precursors, which were premixed with the fuel. The obtained iron oxide particles catalyze soot oxidation in filters. Iron-catalyzed DPFs are considered as safe with respect to their potential to form polychlorinated dibenzodioxins/furans (PCDD/Fs). We reported that a bimetallic potassium/iron FBC supported an intense PCDD/F formation in a DPF. Here, we discuss the impact of fatty acid methyl ester (FAME) biofuel on PCDD/F emissions. The iron-catalyzed DPF indeed supported a PCDD/F formation with biofuel but remained inactive with petroleum-derived diesel fuel. PCDD/F emissions (I-TEQ) increased 23-fold when comparing biofuel and diesel data. Emissions of 2,3,7,8-TCDD, the most toxic congener [toxicity equivalence factor (TEF) = 1.0], increased 90-fold, and those of 2,3,7,8-TCDF (TEF = 0.1) increased 170-fold. Congener patterns also changed, indicating a preferential formation of tetra- and penta-chlorodibenzofurans. Thus, an inactive iron-catalyzed DPF becomes active, supporting a PCDD/F formation, when operated with biofuel containing impurities of potassium. Alkali metals are inherent constituents of biofuels. According to the current European Union (EU) legislation, levels of 5 µg/g are accepted. We conclude that risks for a secondary PCDD/F formation in iron-catalyzed DPFs increase when combusting potassium-containing biofuels.

Isomer-specific investigation of PCDD/F mobility and other fate processes in deep soil cores.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are highly hydrophobic compounds with low migration potential in soil-water. Nevertheless, they have been occasionally reported in subsurface soils hypothesised as the result of facilitated transport processes with colloids or surfactants, or yet unidentified in-situ formation processes. To date, however, the prevalence of deep soil contamination, involved processes and their kinetics remain poorly understood. This study investigated PCDD/F concentrations and isomer profiles through deep soil cores (to 20 m) from agricultural, industrial and urban sites in Queensland, Australia. Based on isomer profiles, a unique source common to all core soils (regardless of depth) was identified, dominated by octachlorodibenzo-p-dioxin (OCDD). The source was consistent with contamination resulting from pesticide impurities. Elevated PCDD concentrations (µg/kg range) to depths up to ∼4-17 m and a continuous increase of peri-chlorinated (1,4,6,9-substituted) isomers through the cores suggested that vertical transport and lateral dechlorination were key post-depositional processes at these sites. The mobility of PCDDs in the present study is far greater than previously reported in soils in general. High estimated mass transport rates for OCDD in four agricultural cores (3.0-6.2% year(-1)) likely reflect significant levels of facilitating species, including surfactants, and intensive rainfall at these sites. The implications of such extensive subsurface transport of PCDD/Fs for groundwater contamination and load estimates may be significant. If the cores of the present study are assumed representative of the region, a total PCDD/F load in the order of 800 tonnes (1.6 tonnes TEQ) could be present in subsurface Queensland coastal soils.

Historical emissions of octachlorodibenzodioxin in a watershed in Queensland, Australia: estimation from field data and an environmental fate model.

An octachlorodibenzodioxin (OCDD)-dominated contamination is present along the coast of Queensland, Australia. Several findings indicate that this contamination originates from pesticide use, although due to limited information on OCDD levels in the pesticides used, estimating past and current emissions of OCDD solely from pesticide use data is unfeasible. We used all the qualitative and quantitative information available on OCDD in pesticides together with a previously validated chemical fate model for a catchment in the Queensland Wet Tropics to back-calculate the emissions of OCDD from measured soil concentrations. We estimate that under different emission scenarios an average of 2,500 kg of OCDD was emitted within the modelled 1,685 km2 (Tully river) catchment between 1950 and 2010. Because this catchment represents only approximately 0.85% of the whole coast of Queensland under a similar contamination, the total amount of OCDD released in this region is considerably larger. For all emission scenarios, we could show that the OCDD currently present in agricultural soil is a result of historical emissions, and current-day emissions are less important in comparison to past emissions. Overall 18% was lost by degradation and 62% was buried below the agricultural surface soil, as a result of facilitated transport.

Trace analysis of hydrophobic micropollutants in aqueous samples using capillary traps.

Studying the fate of persistent organic pollutants (POPs) in glacier environments scientist face the challenge of snow and ice samples, in which concentrations of these pollutants are at the ultra-trace level and the amount of sample available is often very limited. We have improved an extraction method for hydrophobic organic pollutants such as polychlorinated biphenyls (PCBs) in aqueous media to meet the requirements of these challenging samples. It is based on partitioning of the analytes from the water into the polydimethylsiloxane (PDMS) coating of an open tubular-fused-silica capillary. By comparison with conventional liquid-liquid extraction, we validated the method for six indicator PCBs, covering a wide range of polarity. The new method has very low detection limits of 10-20pg/L for the investigated PCBs, a small uncertainty between 9% and 37%, depending on concentration, and requires a small sample volume of less than one liter. Further, it is characterized by easy handling and reduced organic solvents consumption. The method is comparatively insensitive to contamination, reproducible, and suitable for a wide range of applications.