High-intensity interval training improved fasting blood glucose and lipid profiles in type 2 diabetic rats more than endurance training; possible involvement of irisin and betatrophin.

BACKGROUND AND AIMS: In this study, we aimed to investigate the effects of 10 weeks of high-intensity interval training (HIIT) and endurance training (END) on irisin, betatrophin, insulin, fasting blood glucose (FBG) concentrations, and lipid profiles in diabetic rats. METHODS: Twenty-four Wistar rats (weight: 200-250 g) were randomly assigned into four groups as follows: (1) control (Cnt), (2) diabetic (Dibt), (3) diabetic HIIT (Dibt-HIIT), and (4) diabetic END (Dibt-END). For inducing diabetes, after 12 h of food starvation, nicotinamide (120 mg/kg) and streptozotocin (STZ; 65 mg/kg) were intraperitoneally injected. The diabetic training groups received 10 weeks of HIIT or END training following the induction of diabetes. Twenty-four hours following the last training session, blood serum samples were collected for evaluating the concentration of irisin, betatrophin, and insulin hormones through enzyme-linked immunosorbent assay. RESULTS: FBG and lipid profiles were measured by biochemical kits. A significant increase in the serum concentration of irisin (p < 0.05), betatrophin (p < 0.05), and insulin (p < 0.001) and significant decrease in the FBG (P < 0.01) and lipid profiles (p < 0.01) were observed in the Dibt-HIIT group compared to the Dibt-END group. In addition, irisin revealed a significant positive association with betatrophin and insulin values in diabetic training groups (p < 0.01). CONCLUSIONS: It seems that HIIT leads to a more extensive improvement in diabetic conditions compared to the END training. Therefore, HIIT appears to be an important time-efficient approach for the treatment of type 2 diabetes.

Peroxisome proliferator-activated receptor gamma expression in peripheral blood mononuclear cells and angiopoietin-like protein 4 levels in obese children and adolescents.

PURPOSE: The peroxisome proliferator-activated receptor γ (PPARγ) is highly expressed in adipose tissue and functions as transcriptional regulator of metabolism and adipocyte differentiation. Angiopoietin-like protein 4 (ANGPTL4), a central player in various aspects of energy homoeostasis, is induced by PPARγ. The aim of this study was to evaluate ANGPTL4 plasma levels and PPARγ gene expression in peripheral blood mononuclear cells (PBMCs) of children and adolescents with obesity and their association with metabolic parameters. METHODS: Seventy children and adolescents (35 obese and 35 age- and gender-matched control subjects), were selected. PBMCs were separated and their total RNA was extracted. After cDNA synthesis, PPARG gene expression was analyzed by real-time PCR. Relative differences in gene expression were calculated by ΔCt method using ß-actin as a normalizer. Serum ANGPTL4 and insulin were measured using ELISA, and insulin resistance (IR) was calculated by the homeostatic model assessment of insulin resistance (HOMA-IR). Fasting plasma glucose (FPG), triglyceride, total cholesterol, LDL-C and HDL-C were also measured. RESULTS: The expression of the PPARG gene as well as the plasma ANGPTL4 levels were significantly diminished in obese subjects as compared to control ones. However, they were not significantly different in obese children with IR compared to obese children without IR or in those with or without metabolic syndrome. A significant positive correlation was found between PPARγ and ANGPTL4 (r = 0.364, p = 0.002). PPARγ expression levels were also significantly correlated with FPG (r = -0.35, p = 0.003). CONCLUSION: PPARγ is decreased in childhood obesity and may be responsible for diminished ANGPTL4 levels.

Bisphenol-A removal in various wastewater treatment processes: operational conditions, mass balance, and optimization.

Bisphenol-A (BPA) was analyzed in 499 liquid and 347 solid samples collected from twenty-five wastewater treatment plants (WWTPs) to investigate parameters affecting BPA occurrence, removal, and fate. Lagoons, chemically-assisted primary treatment, secondary treatment, and advanced treatment processes were included. Median BPA concentrations in influent and final effluent were 400 ng/L and 150 ng/L, respectively. Median removal efficiencies ranged from 1 to 77%. Respective median BPA levels in primary sludge, secondary biological sludge, and biosolids were 230, 260, and 460 ng/g with digested biosolids having the highest concentrations. The biological aerated filter and membrane bioreactor processes showed the best performance, while chemically-assisted primary treatment achieved the lowest removal. Biodegradation and sorption contributing to BPA removal were influenced by operational conditions: hydraulic retention time (HRT), solids retention time (SRT), and mixed liquor suspended solids (MLSS). The influence of HRT, SRT, and MLSS in the bioreactor was stronger during cold temperatures. In order to achieve above 80% removal, the required conditions for HRT, SRT, and MLSS were 13 h, 7 days, and 1600 mg/L during summer (median temperature 19 °C) and 13 h, 17 days, and 5300 mg/L during winter (median temperature 10 °C); indicating that longer SRT and higher MLSS were needed during winter. BPA's sorption tendency to sludge was strongly influenced by the degree of nitrification and HRT.

Occurrence and fate of four novel brominated flame retardants in wastewater treatment plants.

Four novel brominated flame retardants (NBFRs), i.e., decabromodiphenylethane (DBDPE), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), pentabromoethylbenzene (PBEB), and hexabromobenzene (HBB) were studied in 377 liquid samples and 288 solid samples collected from 20 wastewater treatment plants. Lagoon, primary, secondary, and advanced treatment processes were included, in order to investigate NBFR occurrence and the effects of WWTP operational conditions on NBFR removal. Median influent and effluent levels were 14 to 3,700 and 1.0 to 180 pg/L respectively, with DBDPE being the highest in both. Overall median removal efficiencies for DBDPE, BTBPE, HBB, and PBEB across all process types were 81 to 93, 76 to 98, 61 to 97, and 54 to 97 %, respectively with advanced treatment processes obtaining the best removals. NBFRs removal was related to retention time, surface loading rate, and biomass concentration. Median NBFR levels in treated biosolids were 80 to 32,000 pg/g, influenced by solids treatment processes.

Removal of pharmaceuticals and personal care products in a membrane bioreactor wastewater treatment plant.

Ninety-nine pharmaceuticals and personal care products (PPCPs) were analyzed in influent, final effluent, and biosolids samples from a wastewater treatment plant employing a membrane bioreactor (MBR). High concentrations in influent were found for acetaminophen, caffeine, metformin, 2-hydroxy-ibuprofen, paraxanthine, ibuprofen, and naproxen (10(4)-10(5) ng/L). Final effluents contained clarithromycin, metformin, atenolol, carbamazepine, and trimethoprim (>500 ng/L) at the highest concentrations, while triclosan, ciprofloxacin, norfloxacin, triclocarban, metformin, caffeine, ofloxacin, and paraxanthine were found at high concentrations in biosolids (>10(3) ng/g dry weight). PPCP removals varied from -34% to >99% and 23 PPCPs had ≥90% removal. Of the studied PPCPs, 26 compounds have been rarely or never studied in previous membrane bioreactor (MBR) investigations. The removal pathway showed that acetaminophen, 2-hydroxy-ibuprofen, naproxen, ibuprofen, codeine, metformin, enalapril, atorvastatin, caffeine, paraxanthine, and cotinine exhibited high degradation/transformation. PPCPs showing strong sorption to solids included triclocarban, triclosan, miconazole, tetracycline, 4-epitetracycline, norfloxacin, ciprofloxacin, doxycycline, paroxetine, and ofloxacin. Trimethoprim, oxycodone, clarithromycin, thiabendazole, hydrochlorothiazide, erythromycin-H2O, carbamazepine, meprobamate, and propranolol were not removed during treatment, and clarithromycin was even formed during treatment. This investigation extended our understanding of the occurrence and fate of PPCPs in an MBR process through the analysis of the largest number of compounds in an MBR study to date.

Parameters affecting the formation of perfluoroalkyl acids during wastewater treatment.

This study examined the fate and behaviour of perfluoroalkyl acids (PFAAs) in liquid and solid samples from five different wastewater treatment types: facultative and aerated lagoons, chemically assisted primary treatment, secondary aerobic biological treatment, and advanced biological nutrient removal treatment. To the best of our knowledge, this is the largest data set from a single study available in the literature to date for PFAAs monitoring study in wastewater treatment. Perfluorooctanoic acid (PFOA) was the predominant PFAA in wastewater with levels from 2.2 to 150ng/L (influent) and 1.9 to 140ng/L (effluent). Perfluorooctanesulfonic acid (PFOS) was the predominant compound in primary sludge, waste biological sludge, and treated biosolids with concentrations from 6.4 to 2900ng/g dry weight (dw), 9.7 to 8200ng/gdw, and 2.1 to 17,000ng/gdw, respectively. PFAAs were formed during wastewater treatment and it was dependant on both process temperature and treatment type; with higher rates of formation in biological wastewater treatment plants (WWTPs) operating at longer hydraulic retention times and higher temperatures. PFAA removal by sorption was influenced by different sorption tendencies; median log values of the solid-liquid distribution coefficient estimated from wastewater biological sludge and final effluent were: PFOS (3.73)>PFDA (3.68)>PFNA (3.25)>PFOA (2.49)>PFHxA (1.93). Mass balances confirmed the formation of PFAAs, low PFAA removal by sorption, and high PFAA levels in effluents.

Occurrence and fate of antibiotic, analgesic/anti-inflammatory, and antifungal compounds in five wastewater treatment processes.

The presence of pharmaceuticals and personal care products (PPCPs) in the aquatic environment as a result of wastewater effluent discharge is a concern in many countries. In order to expand our understanding on the occurrence and fate of PPCPs during wastewater treatment processes, 62 antibiotic, analgesic/anti-inflammatory, and antifungal compounds were analyzed in 72 liquid and 24 biosolid samples from six wastewater treatment plants (WWTPs) during the summer and winter seasons of 2010-2012. This is the first scientific study to compare five different wastewater treatment processes: facultative and aerated lagoons, chemically-enhanced primary treatment, secondary activated sludge, and advanced biological nutrient removal. PPCPs were detected in all WWTP influents at median concentrations of 1.5 to 92,000 ng/L, with no seasonal differences. PPCPs were also found in all final effluents at median levels ranging from 3.6 to 4,200 ng/L with higher values during winter (p<0.05). Removal efficiencies ranged between -450% and 120%, depending on the compound, WWTP type, and season. Mass balance showed that the fate of analgesic/anti-inflammatory compounds was predominantly biodegradation during biological treatment, while antibiotics and antifungal compounds were more likely to sorb to sludge. However, some PPCPs remained soluble and were detected in effluent samples. Overall, this study highlighted the occurrence and behavior of a large set of PPCPs and determined how their removal is affected by environmental/operational factors in different WWTPs.

Polybrominated diphenyl ethers in sewage sludge and treated biosolids: effect factors and mass balance.

Polybrominated diphenyl ether (PBDE) flame retardants have been consistently detected in sewage sludge and treated biosolids. Two hundred and eighty-eight samples including primary sludge (PS), waste biological sludge (WBS) and treated biosolids from fifteen wastewater treatment plants (WWTPs) in Canada were analyzed to investigate the factors affecting accumulation of PBDEs in sludge and biosolids. Factors examined included environmental/sewershed conditions and operational parameters of the WWTPs. PBDE concentrations in PS, WBS and treated biosolids were 230-82,000 ng/g, 530-8800 ng/g and 420-6000 ng/g, respectively; BDE-209,-99, and -47 were the predominant congeners. Concentrations were influenced by industrial input, leachate, and temperature. Several examinations including the measurement of BDE-202 indicated minimal debromination during wastewater treatment. Estimated solids-liquid distribution coefficients were moderately correlated to hydraulic retention time, solids loading rate, mixed liquor suspended solids, solids retention time, and removal of organic solids, indicating that PBDE partitioning to solids can be optimized by WWTPs' operational conditions. Solids treatment type strongly affected PBDE levels in biosolids: 1.5 times increase after solids digestion, therefore, digestion efficiency could be a potential factor for variability of PBDEs concentration. In contrast, alkaline treatment reduced PBDE concentrations in biosolids. Overall, mass balance approaches confirmed that PBDEs were removed from the liquid stream through partitioning to solids. Variability of PBDE levels in biosolids could result in different PBDEs burdens to agricultural land, and different exposure levels to soil organisms.

Parameters affecting the occurrence and removal of polybrominated diphenyl ethers in twenty Canadian wastewater treatment plants.

This study determined PBDE levels in influent, primary effluent, and final effluent collected from diverse treatment processes including four aerated lagoons, two facultative lagoons, four primary treatments, eight secondary biological treatments and two advanced treatments. Parameters examined for correlation included seasonal temperature, community sizes, industrial inputs, and operational conditions. PBDE levels in influent were 21-1000 ng/L (median 190 ng/L). Higher concentrations in influent samples were found during summer, and in WWTPs which treated leachate and higher proportions of industrial wastewater vs. residential wastewater. Final effluent levels ranged between 3 and 270 ng/L (median 12 ng/L). Among all congeners, the sum of BDE-209, -47 and -99 accounted for 79 and 71% of total PBDEs in influent and final effluent, respectively, with BDE-209 having the highest proportion. Median removal efficiencies for all process types exceeded 90% except primary treatment at 70%. PBDE levels and removals were correlated to the levels and removals of conventional parameters that represent wastewater strength, such as chemical oxygen demand and total suspended solids. The role of the primary clarifier was significant (∼82% removal) and removal was associated with hydraulic retention time (HRT) and surface loading rate. Best removal of PBDEs was achieved at greater than 2000 mg/L mixed liquor suspended solids (MLSS), longer than 10 h of HRT, and 9 days of solids retention time.

Decamethylcyclopentasiloxane (D5) spiked sediment: bioaccumulation and toxicity to the benthic invertebrate Hyalella azteca.

Chronic toxicity and bioaccumulation of decamethylcyclopentasiloxane (D5) to Hyalella azteca was examined in a series of spiked sediment exposures. Juvenile H. azteca were exposed for 28d (chronic) to a concentration series of D5 in two natural sediments of differing organic carbon content (O.C.) and particle size composition. The chronic, LC50s were 191 and 857µgD5g(-1) dry weight for Lakes Erie (0.5% O.C.) and Restoule (11% O.C.) respectively. Inhibition of growth only occurred with the L. Restoule spiked sediment with a resultant EC25 of 821µgg(-1)dw. Lethality was a more sensitive endpoint than growth inhibition. Biota sediment accumulation factors (BSAFs, 28d) were <1 indicating that D5 did not bioconcentrate based on lipid normalized tissue concentrations and organic carbon normalized sediment concentrations. Organic carbon (OC) in the sediment appeared to be protective, however normalization to OC did not normalize the toxicity. Normalization of D5 concentrations in the sediments to sand content did normalize the toxicity and LC50 values of 3180 and 3570µg D5g(-1) sand dw were determined to be statistically the same.

Polybrominated diphenyl ethers and their methoxylated and hydroxylated analogs in Brown Bullhead (Ameiurus nebulosus) plasma from Lake Ontario.

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) were detected and quantified in Brown Bullhead (Ameiurus nebulosus) from Lake Ontario. Samples were collected in 2006 from three different locations near the city of Toronto: Frenchman's Bay, Toronto Island, and Tommy Thompson Park. A total of 117 plasma samples were pooled into 19 samples, separating males and females by site of capture. Pooled samples were analyzed for 36 PBDEs, 20 MeO-PBDEs and 20 OH-PBDEs, but only six PBDEs, five MeO- and eight OH-compounds were confirmed against standards currently available. These peaks were quantified as "identified" peaks, while peaks matching ion ratios but not matching the retention time of the available standards were quantified as "unidentified" peaks. Both "identified" and "unidentified" concentrations were combined to obtain a total concentration. No significant variations were obtained for total PBDE concentrations, ranging from 3.33 to 9.02 ng g(-1)wet weight. However, OH- and MeO-PBDE totals ranged over 1 order of magnitude among the samples (not detected - 3.57 ng g(-1)wet weight for OH-PBDEs and not detected -0.10 ng/g wet weight for MeO-PBDE). The results of this study suggested that these compounds are ubiquitous in biota. Source estimation of MeO- and OH-PBDEs in freshwater fish were discussed. Considering that up to date no freshwater sources for MeO- or OH-PBDEs have been reported, concentrations found should be mainly related to bioaccumulation from anthropogenic sources, although other sources could not be dismissed.

Fathead minnow (Pimephales promelas) embryo to adult exposure to decamethylcyclopentasiloxane (D5).

The cyclic siloxane decamethylcyclopentasiloxane (D5) is a high production volume chemical which has recently been assessed under the Canadian Chemicals Management Plan (CMP). Cyclic volatile methyl siloxanes (cVMS) are one of the challenge substances in the CMP batches. To provide toxicity and growth information on a species of relevance to the Canadian environment, we assessed D5 in a fathead minnow (Pimephales promelas) embryo to young adult assay. The test was 65d in length, and exposed fathead minnow eggs to juveniles until near maturity (60d post-hatch). The D5 concentrations in flow-through fish exposure aquaria were about one-third of nominal D5 concentrations. Fathead minnows were exposed to 0.25, 0.82, 1.7, 3.6, and 8.7µgL(-1) D5. During the exposure of fathead minnows to D5 there were few effects seen. Egg hatching and larval fish survival and growth were normal. Juvenile fish survival and growth were good in all environmentally-relevant concentrations of D5, and were similar to control fish. The two highest D5 concentrations (8.7µgL(-1) and 3.6µgL(-1), mean measured D5) increased the condition factors of fathead minnows compared to water control and DMSO control fish. Although there were few effects of D5 in our fathead minnow study, the compound was taken up and stored in fish bodies over the 65-d exposure. The bioconcentration factor for D5 in fathead minnows was 4450, for the lowest environmentally-relevant D5 exposure water concentrations, and 4920 for all D5 exposure concentrations tested.

Occurrence of co-planar polybrominated/chlorinated biphenyls (PXBs), polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in breast milk of women from Spain.

In this study, for the first time, levels and accumulation profiles of eight currently available polybrominated/chlorinated biphenyl congeners (PXBs; XB-77, -105, -118, -126A, -126B, -126C, -156 and -169, named according to IUPAC nomenclature) in human breast milk collected form Spanish women in 2005 were reported. Concentrations and congener specific profiles of polychlorinated biphenyls (PCBs), including co-planar PCBs, (co-PCBs) and polybrominated diphenyl ethers (PBDEs) were also reported. A concentration of 0.45 pg g(-1) lipid weight was found for total PXBs, and arithmetic mean concentrations of 125, 25 and 5.5 ng g(-1) lipid weight were determined for total PCBs, co-PCBs and total PBDEs respectively. Detectable levels of all congeners investigated, except CB-123 and XB-169 were found. Levels of PCBs were similar to those found in Spanish samples collected after 2000, and lower than those obtained before 2000. CB-138, -153 and -180 were the predominant PCB congeners. PBDE levels, dominated by BDE-47, -99, -100 and -209, were lower than PCB levels. PXB concentrations were the lowest, with XB-156 being the most abundant. The concentration levels of PCBs and PBDEs found in this study were in the same range as those from other European countries. Levels of PXBs were much lower than published values determined in Japan which were the only data found in the literature.

Dietary exposure of juvenile common sole (Solea solea L.) to polybrominated diphenyl ethers (PBDEs): Part 2. Formation, bioaccumulation and elimination of hydroxylated metabolites.

The uptake, elimination and transformation of six PBDE congeners (BDE-28, -47, -99, -100, -153, -209) were studied in juvenile common sole (Solea solea L.) exposed to spiked contaminated food over a three-month period, and then depurated over a five-month period. Methoxylated (MeO-) and hydroxylated (OH-) PBDEs were determined in fish plasma exposed to PBDEs and compared to those obtained in control fish. While all MeO- and some OH- congeners identified in fish plasma were found to originate from non-metabolic sources, several OH- congeners, i.e., OH-tetraBDEs and OH-pentaBDEs, were found to originate from fish metabolism. Among these, 4'-OH-BDE-49 was identified as a BDE-47 metabolite. Congener 4'-OH-BDE-101, identified here for the first time, may be the result of BDE-99 metabolic transformation. Our results unequivocally showed that PBDEs are metabolised in juvenile sole via the formation of OH- metabolites. However, this was not a major biotransformation route compared to biotransformation through debromination.

Spatial distribution of hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs) and organochlorines in bivalves from Japanese coastal waters.

In order to elucidate the spatial distribution of brominated flame retardants (BFRs) in the Japanese coastal environment, hexabromocyclododecanes (HBCDs), polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs: PCBs, DDTs, CHLs, HCHs, HCB) were determined in bivalves (oysters and mussels) collected from Japanese coastal waters. HBCDs and PBDEs were detected in all samples analyzed. Concentration ranges of HBCDs were 12-5200 ng g(-1) lipid wt., followed by PCBs (20-3100 ng g(-1))>PBDEs (3.1-86 ng g(-1) lipid wt.). The highest concentration of HBCDs was found in the Osaka region. This result indicates that HBCDs are ubiquitous and predominant compounds in bivalves from the Japanese coastal waters. Since no species differences between oysters and mussels were observed for the bioaccumulation properties of HBCDs and PBDEs, oysters could be utilized for BFR contamination monitoring worldwide as an alternative to mussels. Global comparisons between oysters and mussels showed that HBCD concentrations in Japan are among the highest levels reported from Asia and Europe. Estimated dietary exposures of HBCDs and PBDEs through seafood were 0.45-34 ng kg body weight(-1)d(-1), and 0.054-6.8 ng kg body weight(-1)d(-1), respectively. These exposure levels were more than 1000 times lower than the lowest observable effects or no observable adverse effects levels for HBCDs and PBDEs, respectively.

Northern Rivers Ecosystem Initiative: distribution and effects of contaminants.

In response to a number of recommendations following the Northern Rivers Basin Studies (NRBS) contaminant program, the Northern Rivers Ecosystem Initiative (NREI) focused considerable attention on assessing contaminants from specific sources including pulp mill effluents, atmospheric transport of mercury and the Alberta oil sands operations. NRBS identified a number of major contaminants of concern including polychlorinated biphenyls, dioxins and furans, mercury and various hydrocarbons. Together, the NRBS and the NREI studies have demonstrated major declines in the levels of dioxins and furans over the last decade as pulp and paper mills have changed their process and treatment strategies in response to new Federal regulations. Polychlorinated biphenyls however, continue to be a concern for the region as their levels have not declined in fish and sediments over the course of these studies. Higher levels in sediments downstream of Grande Prairie and Hinton were identified, but the source of these contaminants remains unknown. Chlorinated pesticides were also investigated, and although toxaphene, DDT and other chlorinated organic pesticides were detected in fish tissue, they were present at very low levels. Studies on the oil sands industry in northern Alberta demonstrated limited impacts on the Athabasca River to date, although studies did identify slight to moderate impacts of natural oil seeps on fish and benthic communities in tributary streams. NREI studies also identified endocrine active compounds in the three pulp and paper mill effluents tested, but endocrine disruptive effects in wild fish were minimal. Municipal sewage effluents also contain endocrine active compounds and it is recommended that monitoring continue around these point sources.

A gas chromatography/high-resolution mass spectrometry (GC/HRMS) method for determination of polybrominated diphenyl ethers in fish.

A method for the determination of polybrominated diphenyl ethers (PBDEs) in biota for routine analysis is described. The mass spectroscopic (MS) evaluation of 23 brominated diphenyl ethers, under electron ionization and electron capture negative ion conditions using magnetic sector and quadrupole mass spectrometers, showed that high-resolution mass spectrometry (HRMS) under electron ionization conditions was the most reliable technique, with high selectivity and adequate sensitivity. The instrument detection limit for this method ranged for individual congeners between 4.8 and 0.1 pg for 3-bromodiphenyl ether (BDE-2) and 2,3',4,4'-tetrabromodiphenyl ether (BDE-66), respectively, and method detection limit for each homologue group ranged between 5 pg/g for salmon certified reference material (CRM) and 93 pg/g for lake trout CRM. The effectiveness of this method was evaluated by analyzing the occurrence of PBDEs in commercially available CRMs comprising Lake Ontario lake trout, Pacific herring, and sockeye salmon. The average coefficients of variation for the replicate analyses of PDBEs in several tissue samples were: 25% for lake trout, 36% for Pacific herring, and 34% for sockeye salmon. The average deviations in the inter-laboratory study were: 14% for lake trout, 15% for Pacific herring, and 37% for sockeye salmon. Results indicated that the described method, based on gas chromatography/high-resolution mass spectrometry, is reliable for determining PBDE concentrations in biological tissues.

Factors affecting the occurrence and enantiomeric degradation of hexachlorocyclohexane isomers in northern and temperate aquatic systems.

Concentrations of (alpha- and gamma-hexachlorocyclohexane (HCH), alpha/gamma-HCH ratios, and enantiomer ratios (ER) of alpha-HCH were measured in lakes in the arctic, subarctic, Great Lakes, Canada, and temperate regions, and temperate and arctic wetlands and streams. The highest concentrations of alpha-HCH were found in cold, large, and oligotrophic lakes such as those in the arctic, subarctic, and the upper Great Lakes, which is attributed to greater inputs from atmospheric deposition and slower loss rates relative to warmer, temperate lakes. High alpha/gamma-HCH ratios in northern systems indicate aged HCH that has undergone long-range transport to high latitude areas, whereas low ratios in the lower Great Lakes and small temperate systems indicate recent gamma-HCH usage and residual alpha-HCH concentrations. Enantioselective degradation (ERs ranged from 0.31 to 0.7) was greatest in small, high arctic lakes and streams and in large lakes in the subarctic in which alpha-HCH concentrations and contact time between chemical and sediments are highest and nutrient concentrations are lowest. Low ERs were found in wetlands and streams in which contact between chemical and sediments was greatest. Conversely, minimal enantioselective degradation occurred in temperate small lakes and wetlands (ERs ranging from 0.77 to 1.06), despite the warmer temperatures, greater microbial populations, and nutrient availability. The results suggest that enantioselective degradation is optimized by maximal contact between chemical and sediment substrates in nutrient-poor waters in which, it is hypothesized, oligotrophic bacteria may act as biofilms.

Contaminants in the Canadian Arctic: 5 years of progress in understanding sources, occurrence and pathways.

Recent studies of contaminants under the Canadian Northern Contaminants Program (NCP) have substantially enhanced our understanding of the pathways by which contaminants enter Canada's Arctic and move through terrestrial and marine ecosystems there. Building on a previous review (Barrie et al., Arctic contaminants: sources, occurrence and pathways. Sci Total Environ 1992:1-74), we highlight new knowledge developed under the NCP on the sources, occurrence and pathways of contaminants (organochlorines, Hg, Pb and Cd, PAHs, artificial radionuclides). Starting from the global scale, we examine emission histories and sources for selected contaminants focussing especially on the organochlorines. Physical and chemical properties, transport processes in the environment (e.g. winds, currents, partitioning), and models are then used to identify, understand and illustrate the connection between the contaminant sources in industrial and agricultural regions to the south and the eventual arrival of contaminants in remote regions of the Arctic. Within the Arctic, we examine how contaminants impinge on marine and terrestrial pathways and how they are subsequently either removed to sinks or remain where they can enter the biosphere. As a way to focus this synthesis on key concerns of northern residents, a number of special topics are examined including: a mass balance for HCH and toxaphene (CHBs) in the Arctic Ocean; a comparison of PCB sources within Canada's Arctic (Dew Line Sites) with PCBs imported through long-range transport; an evaluation of concerns posed by three priority metals--Hg, Pb and Cd; an evaluation of the risks from artificial radionuclides in the ocean; a review of what is known about new-generation pesticides that are replacing the organochlorines; and a comparison of natural vs. anthropogenic sources of PAH in the Arctic. The research and syntheses provide compelling evidence for close connectivity between the global emission of contaminants from industrial and agricultural activities and the Arctic. For semi-volatile compounds that partition strongly into cold water (e.g. HCH) we have seen an inevitable loading of Arctic aquatic reservoirs. Drastic HCH emission reductions have been rapidly followed by reduced atmospheric burdens with the result that the major reservoir and transport agent has become the ocean. In the Arctic, it will take decades for the upper ocean to clear itself of HCH. For compounds that partition strongly onto particles, and for which the soil reservoir is most important (e.g. PCBs), we have seen a delay in their arrival in the Arctic and some fractionation toward more volatile compounds (e.g. lower-chlorinated PCBs). Despite banning the production of PCB in the 1970s, and despite decreases of PCBs in environmental compartments in temperate regions, the Arctic presently shows little evidence of reduced PCB loadings. We anticipate a delay in PCB reductions in the Arctic and environmental lifetimes measured in decades. Although artificial radionuclides have caused great concern due to their direct disposal on Russian Shelves, they are found to pose little threat to Canadian waters and, indeed, much of the radionuclide inventory can be explained as remnant global fallout, which was sharply curtailed in the 1960s, and waste emissions released under license by the European reprocessing plants. Although Cd poses a human dietary concern both for terrestrial and marine mammals, we find little evidence that Cd in marine systems has been impacted by human activities. There is evidence of contaminant Pb in the Arctic, but loadings appear presently to be decreasing due to source controls (e.g. removal of Pb from gasoline) in Europe and North America. Of the metals, Hg provokes the greatest concern; loadings appear to be increasing in the Arctic due to global human activities, but such loadings are not evenly distributed nor are the pathways by which they enter and move within the Arctic well understood.