Air monitoring of organochlorine pesticides (OCPs) in Bursa Türkiye: Levels, temporal trends and risk assessment

Monitoring concentration levels of persistent organic pollutants (POPs) is required to evaluate the effectiveness of international regulations to minimize the emissions of persistent organic pollutants (POPs) into the environment. In this manner, we evaluated the spatial and temporal variations of 22 organochlorine pesticides (OCPs) using polyurethane foam passive air samplers at ten stations in Bursa in 2017 and 2018. The highest concentration value for Σ22OCPs was detected in Ağaköy (775 pg/m3) and Demirtaş (678 pg/m3) sampling sites, while the lowest value was observed in Uludağ University Campus (UUC, 284 pg/m3) site. HCB, γ-HCH, Endo I, and Mirex were the most frequently detected OCPs, which shows their persistence. Diagnostic ratios of β-/(α + γ)-HCH have pointed to historical and possible illegal OCP usage in the study area. The seasonality of air concentrations (with spring and summer concentrations higher than winter and autumn concentrations) was well exhibited by α-HCH, β-HCH, ɣ-HCH, HCB, Endo I, and Mirex but not aldrin, dieldrin, and α-chlordane (CC). Levels of OCPs detected in ambient air in the current study were relatively similar to or lower than those reported in previous studies conducted in Türkiye. Back trajectory analysis was applied to identify the possible sources of OCPs detected in the sampling regions. The Clausius-Clapeyron approach was used to investigate the temperature dependence of OCP gas-phase atmospheric concentrations. The data showed that long-range atmospheric transport affects ambient air OCP concentrations in the study area.

Modeling historical budget for β-Hexachlorocyclohexane (HCH) in the Arctic Ocean: A contrast to α-HCH

The historical annual loading to, removal from, and cumulative burden in the Arctic Ocean for β-hexachlorocyclohexane (β-HCH), an isomer comprising 5-12% of technical HCH, is investigated using a mass balance box model from 1945 to 2020. Over the 76 years, loading occurred predominantly through ocean currents and river inflow (83%) and only a small portion via atmospheric transport (16%). β-HCH started to accumulate in the Arctic Ocean in the late 1940s, reached a peak of 810 t in 1986, and decreased to 87 t in 2020, when its concentrations in the Arctic water and air were ∼30 ng m^-3 and ∼0.02 pg m^-3, respectively. Even though β-HCH and α-HCH (60-70% of technical HCH) are both the isomers of HCHs with almost identical temporal and spatial emission patterns, these two chemicals have shown different major pathways entering the Arctic. Different from α-HCH with the long-range atmospheric transport (LRAT) as its major transport pathway, β-HCH reached the Arctic mainly through long-range oceanic transport (LROT). The much higher tendency of β-HCH to partition into the water, mainly due to its much lower Henry's Law Constant than α-HCH, produced an exceptionally strong pathway divergence with β-HCH favoring slow transport in water and α-HCH favoring rapid transport in air. The concentration and burden of β-HCH in the Arctic Ocean are also predicted for the year 2050 when only 4.4-5.3 t will remain in the Arctic Ocean under the influence of climate change.

Hexachlorobenzene-negative ion formation in electron attachment experiments

In this contribution, we report a comprehensive study on the formation of hexachlorobenzene (C₆Cl₆) negative ions probed by low-energy electron interactions from 0 up to 12 eV in a gas-phase crossed beam experiment. The anionic yields as a function of the electron energy reveal a rich fragmentation pattern of the dissociative electron attachment process, yet the most intense ion has been assigned to the non-dissociated parent anion that survives long enough within the detection time window. Other less intense fragment anions have been assigned as Cl^-, Cl₂^-, C₆Cl₄^-, and C₆Cl₅^-. The experimental results are accompanied by quantum chemical calculations at various levels of accuracy, providing an insight into the electronic structure, thermochemical thresholds, electron affinities and structures of neutral and anionic molecular species. The electron attachment process induces a considerable geometry change in the temporary-negative ion relative to the neutral molecule, where the most intense fragment anion assigned to Cl^- can be formed solely through a curve crossing involving a π*/σ* coupling. The yield of chlorine anions shows a signature of vibrational excitation reminiscent of a Jahn-Teller distortion.

Anionic states of C6Cl6 probed in electron transfer experiments

This is the first comprehensive investigation on the anionic species formed during collisions of fast neutral potassium (K) atoms with neutral hexachlorobenzene (C₆Cl₆) molecules in the laboratory frame range from 10 up to 100 eV. In such ion-pair formation experiments we also report a novel K⁺ energy loss spectrum obtained in the forward scattering giving evidence of the most accessible electronic states. The vertical electron affinity of (-3.76 ± 0.20) eV has been obtained and assigned to a purely repulsive transition from the C₆Cl₆ ground state to a state of the temporary negative ion yielding Cl^- formation. These experimental findings are also supported by state-of-the art theoretical calculations on the electronic structure of C₆Cl₆ in the presence of a potassium atom and are used for analysing the lowest unoccupied molecular orbitals participating in the collision process. From the time-of-flight mass spectra recorded in the wide collision energy range, more than 80% of the total anion yield is due to the undissociated parent anion C₆Cl₆^-, C₆Cl₅^- and Cl^- formation. Other fragment anions such as C₆Cl₄^-, C₃Cl₂^-, C₂Cl^- and Cl₂^- that undergo complex internal reactions with the temporary negative ion formed after electron transfer account for less than 20% of the total yield. The joint experimental and theoretical methodologies employed in these electron transfer studies provide the most comprehensive and unique assignments of the hexachlorobenzene anionic species and the role of C₆Cl₆ electronic states in collision induced dissociation to date.

Technical-grade chlordane compromises rat Sertoli cells proliferation, viability and metabolic activity

Environmental contaminants are a daily presence in human routine. Multiple studies highlight the obesogenic activity of some chemicals. Moreover, these compounds have been suggested as a cause of male subfertility and/or infertility. Technical-grade chlordane (TGC) is classified as an endocrine-disruptor chemical, while its classification as obesogen is controversial. Herein, we studied the influence of TGC on Sertoli cells (SCs) metabolism. Rat Sertoli cells (rSCs) were cultured without and in the presence of increasing concentrations (1, 10 and 1000 nM) of TGC. The viability, proliferation, metabolic activity and the metabolic profile of rSCs was assessed. Expression of key glycolysis-related enzymes, transporters and biomarkers of oxidative damage were also evaluated. Our results show that exposure to higher concentrations of TGC decreases SCs proliferation and viability, which was accompanied by increased glucose consumption associated with an upregulation of Glut3 levels. As a result, pyruvate/lactate production were enhanced thus increasing the glycolytic flux in cells exposed to 1000 nM TGC, although lactate dehydrogenase expression and activity did not increase. Notably, biomarkers associated with oxidative damage remained unchanged after exposure to TGC. This is the first report showing that TGC alters glucose rSCs metabolism and the nutritional support of spermatogenesis with consequences for male fertility.

Measurement and modeling the gas/particle partitioning of organochlorine pesticides (OCPs) in atmosphere at low temperatures

The gas/particle (G/P) partition of organochlorine pesticides (OCPs) has been widely investigated and well documented, but rare at low temperature. In this study, seventy-four pairs of air samples in two sampling sites in northeastern China at a wide ambient temperature range of ~63 °C (-40 to +23 °C) were simultaneously collected in both gaseous and particulate phases and eighteen OCPs in these samples were measured and analyzed, among which, partition quotient (K_P) values for fifteen OCPs were determined. Seven models including those have never been used for OCPs were applied to predict the values of K_P, and the results were compared with the monitoring data for the fifteen OCPs. It was found out that, L-M-Y model provided advantages over the other models, with the best agreement to the monitoring data for analyzed OCPs (90.1 ± 11.1% data points within ±1 log unit, RMSE: 0.53 ± 0.18). The predicted maximum partition (MP) domain for eleven OCPs was observed with high values of their logarithm of octanol-air partition coefficient (log K_OA > 12.5), where the log K_P values become a constant (-1.53), indicating that the G/P partition of OCPs is in steady state but not the equilibrium. The Li-Ma-Yang (L-M-Y model) model, considering the wet and dry depositions of particles, elucidates the necessity of non-equilibrium term for the OCPs at low temperature. These results indicate that the L-M-Y model is valid for OCPs, which renders it highly promising for describing the partition behaviors in atmosphere for SVOCs, particularly at low temperature. An equation to calculate the condensation temperature T_C was also derived, which gave a new understanding on the situation of chemicals with equal distribution between gaseous and particulate phases of OCPs and other similar SVOCs, especially in Polar Regions.

Levels of polycyclic aromatic hydrocarbons in Canadian mountain air and soil are controlled by proximity to roads

Concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in soil and XAD-based passive air samples taken from a total of 22 sites along three transects (Revelstoke, Yoho, and Observation, 6-8 sites for each transect) in the mountains of Western Canada in 2003-2004. Median concentrations in air (4-ring PAHs: 33 pg/m(3)) were very low and comparable to those in global background regions such as the Arctic. Low median soil concentrations (16 EPA PAHs: 16 ng/g dry weight) and compositional profiles dominated by naphthalene and phenanthrene are similar to those of tropical soils, indicative of remote regions influenced mostly by PAHs from traffic and small settlements. Comparing levels and composition of PAHs in soils between and along transects indeed suggests a clear relationship with proximity to local sources. Sampling sites that are closer to major traffic arteries and local settlements have higher soil concentrations and a higher relative abundance of heavier PAHs than truly remote sites at higher elevations. This remains the case when the variability in soil organic carbon content between sites is taken into account. Both air/soil concentration ratios and fugacity fractions suggest atmospheric net deposition of four-ring PAHs to soils.

Endosulfan in China 2-emissions and residues

BACKGROUND, AIM, AND SCOPE

Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4 degrees longitude by 1/6 degrees latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan.

METHODS

Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model-SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined.

RESULTS AND DISCUSSION

Historical gridded emission and residue inventories of alpha- and beta-endosulfan in agricultural soil in China with 1/4 degrees longitude by 1/6 degrees latitude resolution have been created. Total emissions were around 10,800 t, with alpha-endosulfan at 7,400 t and beta-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for alpha-endosulfan and 390 t for beta-endosulfan, and the lowest residues were 0.7 t for alpha-endosulfan and 170 t for beta-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of alpha- and beta-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data.

CONCLUSIONS

To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general.

RECOMMENDATIONS AND PERSPECTIVES

The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.

Molecular and stable carbon isotopic characterization of PAH contaminants at McMurdo Station, Antarctica

The molecular and stable carbon isotopic compositions of contaminant polycyclic aromatic hydrocarbons (PAHs) at McMurdo Station, Antarctica were analyzed in samples collected from land and sub-tidal area. PAHs in the study areas were characterized by high amounts of naphthalene and alkylated naphthalenes from petroleum products introduced by human activities in the area. Principal component analysis (PCA) of PAH composition data identified multiple sources of PAH contamination in the study area. Compositional assignments of origins were confirmed using compound specific stable carbon isotopic analysis.

Dichlorodiphenyltrichloroethane usage in the former Soviet Union

DDT (Dichlorodiphenyltrichloroethane), an organochlorine pesticide (OCP), is one of 12 persistent organic pollutants (POPs) that is being proposed for elimination or control under the Stockholm Convention on POPs. This paper presents historical DDT usage in the Former Soviet Union (FSU) from different sources. Although the data from different sources do not agree with each other, the data clearly show that the usage of DDT in the FSU were intensive in the 1950s and 1960s, and the use of DDT continued until early 1990s although DDT was officially banned in 1969/1970 by the FSU government. Two estimations (high and low) are made for the historical annual DDT usage in the FSU. The total DDT usage in the FSU from 1946 and 1990 was 520 kt for the high estimation and 250 kt for the low estimation. Gridded DDT usage inventories in the FSU on a 1 degree longitude by 1 degree latitude grid system are created by using the gridded distribution of cropland density for the FSU, and show that DDT usage varied considerably across the FSU. Most DDT was applied in southern regions of the FSU where agricultural activity was greatest, such as in Moldova and Ukraine followed by the Northern Caucasus region of Russia and the Central Asian republics.

Variation of POP concentrations in fresh-fallen snow and air on an Alpine glacier (Monte Rosa)

To understand better the mechanisms ruling the fate of POPs (persistent organic pollutants) in cold environments, a field campaign sampling fresh-fallen snow and air on an Alpine glacier was carried out during Summer 2003. The concentrations of all analyzed chemicals in fresh-fallen snow show a sharp decrease over time, particularly for the more volatile POPs, confirming the rather limited literature evidence of a rapid decline of such substances from the snowpack and/or ice. Even if the results presented here are preliminary and should be confirmed by further studies, some evidence of the influence of a night/day cycle of temperature on POP deposition and revolatilization mechanisms has been highlighted. Finally, the role of cold condensation and long-range atmospheric transport in the contamination of higher altitudes in this Alpine system has been substantiated, particularly for OC pesticides.

Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data

The Arctic has undergone dramatic change during the past decade. The observed changes include atmospheric sea-level pressure, wind fields, sea-ice drift, ice cover, length of melt season, change in precipitation patterns, change in hydrology and change in ocean currents and watermass distribution. It is likely that these primary changes have altered the carbon cycle and biological systems, but the difficulty of observing these together with sporadic, incomplete time series makes it difficult to evaluate what the changes have been. Because contaminants enter global systems and transport through air and water, the changes listed above will clearly alter contaminant pathways. Here, we review what is known about recent changes using the Arctic Oscillation as a proxy to help us understand the forms under which global change will be manifest in the Arctic. For Pb, Cd and Zn, the Arctic is likely to become a more effective trap because precipitation is likely to increase. In the case of Cd, the natural cycle in the ocean appears to have a much greater potential to alter exposure than do human releases of this metal. Mercury has an especially complex cycle in the Arctic including a unique scavenging process (mercury depletion events), biomagnifying foodwebs, and chemical transformations such as methylation. The observation that mercury seems to be increasing in a number of aquatic species whereas atmospheric gaseous mercury shows little sign of change suggests that factors related to change in the physical system (ice cover, permafrost degradation, organic carbon cycling) may be more important than human activities. Organochlorine contaminants offer a surprising array of possibilities for changed pathways. To change in precipitation patterns can be added change in ice cover (air-water exchange), change in food webs either from the top down or from the bottom up (biomagnification), change in the organic carbon cycle and change in diets. Perhaps the most interesting possibility, presently difficult to predict, is combination of immune suppression together with expanding ranges of disease vectors. Finally, biotransport through migratory species is exceptionally vulnerable to changes in migration strength or in migration pathway-in the Arctic, change in the distribution of ice and temperature may already have caused such changes. Hydrocarbons, which tend to impact surfaces, will be mostly affected by change in the ice climate (distribution and drift tracks). Perhaps the most dramatic changes will occur because our view of the Arctic Ocean will change as it becomes more amenable to transport, tourism and mineral exploration on the shelves. Radionuclides have tended not to produce a radiological problem in the Arctic; nevertheless one pathway, the ice, remains a risk because it can accrue, concentrate and transport radio-contaminated sediments. This pathway is sensitive to where ice is produced, what the transport pathways of ice are, and where ice is finally melted-all strong candidates for change during the coming century. The changes that have already occurred in the Arctic and those that are projected to occur have an effect on contaminant time series including direct measurements (air, water, biota) or proxies (sediment cores, ice cores, archive material). Although these 'system' changes can alter the flux and concentrations at given sites in a number of obvious ways, they have been all but ignored in the interpretation of such time series. To understand properly what trends mean, especially in complex 'recorders' such as seals, walrus and polar bears, demands a more thorough approach to time series by collecting data in a number of media coherently. Presently, a major reservoir for contaminants and the one most directly connected to biological uptake in species at greatest risk-the ocean-practically lacks such time series.

Sources and pathways of selected organochlorine pesticides to the Arctic and the effect of pathway divergence on HCH trends in biota: a review

Historical global usage and emissions for organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethane (DDT), toxaphene and endosulfan, are presented. Relationships between the air concentrations of these OCPs and their global emissions are also discussed. Differences between the pathways of alpha- and beta-HCH to the Arctic Ocean are described in the context of environmental concentrating and diluting processes. These concentrating and diluting processes are shown to control the temporal and spatial loading of northern oceans and that the HCH burdens in marine biota from these oceans respond accordingly. The HCHs provide an elegant example of how hemispheric-scale solvent switching processes can alter the ocean into which an HCH congener partitions, how air-water partitioning controls the pathway for HCHs entering the Arctic, and how the various pathways impact spatial and temporal trends of HCH residues in arctic animals feeding out of marine and terrestrial foodwebs.

Gas-particle partitioning of polychlorinated naphthalenes and non- and mono-ortho-substituted polychlorinated biphenyls in arctic air

Gas-particle partitioning relationships were developed for partitioning of polychlorinated naphthalenes (PCNs) and non- and mono-ortho PCBs in arctic air by regressing observed gas-particle partition coefficients, K(P), at Alert and Dunai in the high Arctic with temperature-adjusted experimental vapor pressures (p(L) degrees ) and octanol-air partition coefficients (K(OA)). Slopes were near -0.5 and 0.5 for log p(L) degrees and log K(OA), respectively, at both sites, indicating that aerosol characteristics and partitioning processes were similar at the two sites. The K(OA) absorption model provided an adequate estimate of the percentage of PCNs and non-/mono-ortho PCBs associated with particulate matter, based on fraction of organic matter (f(OM)) ranging from 0.074 to 0.12, compared to the Junge-Pankow adsorption model, which slightly over-estimated the distribution on particles. There were no indications that partitioning to soot carbon influences the observed gas-particle distribution for PCNs and non-/mono-ortho PCBs in arctic air as has been observed for PAHs in recent studies at temperate locations.

Temporal and spatial variabilities of atmospheric polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and polycyclic aromatic hydrocarbons (PAHs) in the Canadian Arctic: results from a decade of monitoring

The Northern Contaminants Program (NCP) baseline monitoring project was established in 1992 to monitor for persistent organic pollutants (POPs) in Arctic air. Under this project, weekly samples of air were collected at four Canadian and two Russian arctic sites, namely Alert, Nunavut; Tagish, Yukon; Little Fox Lake, Yukon; Kinngait, Nunavut; Dunai Island, Russia and Amderma, Russia. Selected POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, were analyzed in both the gas and particulate phases. This paper summarizes results obtained from this project in the past 5 years. Temporal trends were developed for atmospheric PCBs and OCs observed at Alert using a digital filtration (DF) technique. It was found that trends developed with 5 years of data (1993-1997) did not differ significantly from those determined with 7 years of data (1993-1999). This implies that with the DF technique, long-term trends can still be developed with less than 10 years of data. An acceleration in decline of OC and PCB air concentrations was noted in 1999 for some compounds, although the reason is unknown. Monitoring efforts must continue to assess the effect of this decline on the long-term trends of POPs in the Canadian Arctic. Occasional high trans-/cis-chlordane ratios and heptachlor air concentrations measured at Alert between 1995 and 1997 suggests sporadic fresh usage of chlordane-based pesticides. However, significant decreasing trends of chlordanes along with their chemical signatures has provided evidence that emission of old soil residues is replacing new usage as an important source to the atmosphere. Measurements of OC air concentrations conducted at Kinngait in 1994-1995 and 2000-2001 indicated faster OC removal at this location than at Alert. This may be attributed to the proximity of Kinngait to temperate regions where both biotic and abiotic degradation rates are faster. The PAH concentrations observed at Alert mimic those at mid-latitudes and are consistent with long-range transport to the Arctic, particularly for the lighter PAHs. A decline in particulate PAH was observed, similar to atmospheric sulphate aerosol and can be attributed to the collapse of industrial activity in the former Soviet Union between 1991 and 1995. Spatial comparisons of OC seasonality at Alert, Tagish, Dunai and Kinngait show elevated air concentrations of some compounds in spring. However, elevated spring concentrations were observed for different compounds at different sites. Potential causes are discussed. Further investigation in the atmospheric flow pattern in spring which is responsible for the transport of POPs into the Arctic is required. OC and PCB air concentrations at Alert were found to be influenced by two climate variation patterns, the North Atlantic Oscillation (NAO) and the Pacific North American (PNA) pattern. Planetary atmospheric patterns must be taken into account in the global prediction and modelling of POPs in the future.

The transport of beta-hexachlorocyclohexane to the western Arctic Ocean: a contrast to alpha-HCH

A large database for alpha-hexachlorocyclohexane (alpha-HCH), together with multimedia models, shows this chemical to have exhibited classical 'cold condensation' behavior. The surface water of the Arctic Ocean became loaded between 1950 and 1990 because atmospheric transport of alpha-HCH from source regions to the Arctic was rapid and because alpha-HCH partitioned strongly into cold water there. Following emission reductions during the 1980s, alpha-HCH remained trapped under the permanent ice pack, with the result that the highest oceanic concentrations in the early 1990s were to be found in surface waters of the Canada Basin. Despite a much stronger partitioning into water than for alpha-HCH, beta-HCH did not accumulate under the pack ice of the Arctic Ocean, as might be expected from the similar emission histories for the two chemicals. Beta-HCH appears to have loaded only weakly into the high Arctic through the atmosphere because it was rained out or partitioned into North Pacific surface water. However, beta-HCH has subsequently entered the western Arctic in ocean currents passing through Bering Strait. Beta-HCH provides an important lesson that environmental pathways must be comprehensively understood before attempting to predict the behavior of one chemical by extrapolation from a seemingly similar chemical.

Agricultural soil as a potential source of input of organochlorine pesticides into a nearby pond

A study was conducted in the southeastern region of Buenos Aires province, Argentina, to assess an agricultural soil as a potential source of organochlorine (OC) pesticides for the aquatic biota of a nearby pond. We analyzed gamma-HCH (lindane), still in use, and the following banned compounds: DDT, DDE, DDD heptachlor, heptachlor epoxide, aldrin, dieldrin and endrin in soil, bulrush, grass shrimp and fish using gas chromatography with electron capture detection (GC-ECD). Among the OC pesticides, lindane was most dominant in the soil (32.6 ng/g dry wt in the upper and 173.9 ng/g dry wt in the lower horizon) and bulrush (1.9 pg/g lipid). Macrophyte also accumulated high levels of heptachlor epoxide (1.5 pg/g lipid). Heptachlor, although present in the soil, was below the detection limit in all aquatic biota studied. Its primary degradation product, heptachlor epoxide, was found in both soil and biota samples. DDT was found at low levels in the surface soil (6.8 ng/g dry wt), but at higher concentrations in fish (3.6 pg/g lipid), although levels were still below permissible levels for human consumption. Since most of the compounds were found in both soil and aquatic biota, our study suggests that agricultural soil could be an important source for OC pesticides in the nearby pond.

Spatial differences in persistent organochlorine pollutant concentrations between the Bering and Chukchi Seas (1993)

During August-September 1993, a joint Russian-United States expedition to the Bering and Chukchi Seas took place. Surface water samples were collected from 21 sites and separated into dissolved (duplicates) and suspended solids; 19 sediment and 6 air samples were also collected. These samples were analysed for 19 organochlorine pesticides, 11 chlorobenzenes and 113 PCB congeners. The report provides data on selected compounds which occured in > or = 75% of the water samples. Highest water concentrations were observed for HCH in open waters north and south of the Bering Strait, both regions being similar (alpha-HCH; 2.2 ng/L and lindane: 0.35 ng/L). Air levels observed were also constant (alpha-HCH; 0.041 ng/m3, lindane: 0.0093 ng/m3). Suspended solids and air particulares contributed little to the concentrations in their respective media, an observation common to all analytes except for the PCBs and the DDT residues. The sum of PCB concentrations in water were higher in the Bering Sea area compared to the Chukchi Sea (1.0 vrs 0.67 ng/L) and lower for air (0.46 vrs 0.23 ng/m3). Sum of DDT in water was higher in the Bering Sea than in the Chukchi Sea (0.23 vrs 0.15 ng/L) while in sediments and air, the Bering Sea concentrations were lower (0.95 vrs 1.6 ng/g and 36 vrs 56 pg/m3, respectively). Other organochlorine compounds for which data are presented include: pp'-DDE, pp'-DDT, dieldrin, HCB, 3 chlorobenzenes and 3 PCB congeners. Fluxes of all these chemicals through the Berin Strait are estimated; they ranged from 57 t/a (alpha-HCH) through 26 t/a (for sum of PCBs) to 0.2 t/a (pp'-DDE, dieldrin and 1,2,3-trichlorobenzene). Fugacity ratios for the HCHs and PCBs indicate the alpha-HCH is degassing in both the Bering and Chukchi Seas and that the gamma-isomer is degassing in the Bering Sea and is close to equilibrium (weakly absorbing) in the Chuchi Sea; the sum of PCBs are strongly absorbing in both areas.

Beyond risk: an ecological paradigm to prevent global chemical pollution

Since World War II, synthetic chemical pollutants have accumulated in the environment and food webs on a global basis, have damaged wildlife populations, and may pose large-scale hazards to human health. Despite the global nature of this problem, the vast majority of environmental regulations focus on preventing local risks using risk assessment of individual compounds, discharge permits, and control and disposal technologies. The current approach has failed to prevent global contamination and environmental damage because it underestimates the scale, complexity, and diversity of the hazards of chemical pollution. Fundamental shifts in the mode of chemical assessment and policy are required; a new framework should focus on chemical classes rather than individual substances, convert industrial processes to prevent the production and use of persistent and/or bioaccumulative substances, and shift the default state of pollution policy in the face of uncertainty from permission to restriction.

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.

Effects of local and distant contaminant sources: polychlorinated biphenyls and other organochlorines in bottom-dwelling animals from an Arctic estuary

Elevated concentrations of organochlorines in the tissues of large marine predators in the Canadian Arctic are well documented. This paper presents some of the first data on the composition and distribution of chlorinated organic compounds in some arctic coastal animals found at lower levels of the marine food chain. Organisms include bottom-dwelling invertebrates: clams (Mya truncata), mussels (Mytilus edulis), sea urchins (Strongylocentrotus droebachiensis) and fish: sculpins (Myoxocephalus quadricornis). The majority of samples were collected in the vicinity of Cambridge Bay, Northwest Territories (NWT), Canada; however, samples were also collected near another inhabited area (Hall Beach, NWT) and at a reference site (Wellington Bay, NWT). PCBs and other organochlorines typically originate in more industrialized parts of the northern hemisphere, enter the Arctic, and are subsequently biomagnified. In this study, differences in the PCB congener compositions and concentrations, as well as the relative concentrations of a larger suite of organochlorines in biota, allowed the discrimination between local and distant PCB sources. Terrestrial runoff from southern Victoria Island, NWT, has resulted in localized elevation of PCBs and chlorinated pesticides in marine sediment and bottom-dwelling animals. The major inputs of PCBs to coastal waters within Cambridge Bay were derived from local sources (the hamlet dump and DEW Line site). In addition, transport from more distant sources via riverine input accounts for locally elevated concentrations of other organochlorines in upper Cambridge Bay. This process may also account for concentrations of all measured organochlorines that are higher in Wellington Bay than in Queen Maud Gulf. The high PCB concentrations in the whole tissue (excluding liver) or livers of four-horned sculpins in Cambridge Bay (up to 220 ng/g and 1950 ng/g, respectively) and, to a lesser extent, Wellington Bay (3.8 ng/g and 47 ng/g, respectively) reflect a strong tendency for biomagnification of PCBs in coastal benthic communities.

Air-water gas exchange and evidence for metabolism of hexachlorocyclohexanes in Resolute Bay, N.W.T

Paired air and water samples were collected at Resolute Bay (74 degrees N, 95 degrees W) in summer 1992 to estimate the direction of gas exchange of hexachlorocyclohexanes (HCHs) and investigate possible loss processes in the water column. Average concentrations of alpha-HCH and gamma-HCH in ocean surface water were 4.7 +/- 0.9 and 0.44 +/- 0.11 ng/l, respectively. These alpha- and gamma-HCH levels are approximately 66-104% and 54-72% of values reported for the central Arctic Ocean at the Canadian Ice Island in 1986. Mean atmospheric concentrations of alpha-HCH and gamma-HCH (114 +/- 16 and 9.8 +/- 1.3 pg/m3) were 2-3 times lower than summer Arctic levels in the 1980s. The ocean surface water (-1.4 degrees C) was approximately within Henry's Law equilibrium with respect to atmospheric gamma-HCH levels. Water/air fugacity ratios were 1.03 for gamma-HCH and 1.57 for alpha-HCH, indicating a slight potential for volatilization of alpha-HCH. The two alpha-HCH enantiomers in air and water were separated by chromatography on a gamma-cyclodextrin capillary column. The enantiomeric ratio (ER = ratio of (+)alpha-HCH/(-)alpha-HCH) in air was 1.00 +/- 0.04. This agrees excellently with ER = 1.00 +/- 0.01 found for a racemic alpha-HCH standard. The (+) enantiomer was depleted in seawater, resulting in ER = 0.93 +/- 0.06 in Resolute Bay. ERs of samples from Amituk Lake on Cornwallis Island ranged from 0.65 to 0.99, depending on location, date and relative contributions of fresh snowmelt and older lake water. These results suggest that microbial degradation of HCHs is taking place in Arctic lakes and near-shore marine waters.

Arctic contaminants: sources, occurrence and pathways

Potentially toxic organic compounds, acids, metals and radionuclides in the northern polar region are a matter of concern as it becomes evident that long-range transport of pollution on hemispheric to global scales is damaging this part of the world. In this review and assessment of sources, occurrence, history and pathways of these substances in the north, the state of knowledge of the transport media--the ocean and atmospheric circulation--is also examined. A five-compartment model of the northern region is developed with the intent of assessing the pathways of northern contaminants. It shows that we know most about pathways of acids, metals and radionuclides and least about those of complex synthetic organic compounds. Of the total annual inputs of anthropogenic acidic sulphur and the metals lead and cadmium to the Arctic via the atmosphere, an estimated 10-14% are deposited. A water mass budget for the surface layer of the Arctic Ocean, the most biologically active part of that sea, is constructed to examine the mass budget for one of the major persistent organochlorine compound groups found in remote regions, hexachlorocyclohexanes (HCH), one isomer of which is lindane. It is concluded that both the atmosphere and the ocean are important transport media. Even for the HCH substances which are relatively easily measured and simple in composition compared to other synthetic organics, we know little about the occurrence and environmental physical/chemical characteristics that determine pathways into the food chain. More environmental measurements, chemical characterization studies and environmental chemical transport modelling are needed, as is better knowledge of the circulation of the Arctic Ocean and the marine food web.

Organochlorine contaminants in narwhal (Monodon monoceros) from the Canadian Arctic

Organochlorine pesticides (DDT, chlordane, polychlorinated camphenes (PCCs), dieldrin, hexachloroheclohexanes (SigmaHCH), mirex), polychlorinated biphenyl congeners (PCBs) and chlorobenzenes (SigmaCBz) were determined in blubber and liver of narwhal (Monodon monoceros) collected during 1982-1983 from Pond Inlet on northern Baffin Island in the Canadian Arctic. PCCs were the predominate organochlorines in narwhal blubber, ranging in concentration from 2990 to 13 200 ng g(-1) (wet wt) in males and from 1910 to 8390 ng g(-1) in females. PCCs consisted of two major components, an octachlorobornane and a nonachlorobornane with gas chromatographic retention times of 1.05 and 1.22, relative to 4,4'-DDE. SigmaPCB concentrations in blubber ranged from 2250 to 7290 ng g(-1) in males and from 894 to 5710 ng g(-1) in females. Seven PCB congeners (tetra-, penta- and hexachlorobiphenyls) accounted for 45% of total PCB (SigmaPCB) in narwhal blubber. Narwhal had 1.4- to 8.6-fold higher ratios of tetra- and pentachlorobiphenyls to PCB-153 (2,2',4,4',5,5'-hexachlorobiphenyl), lower 4,4'-DDE/SigmaDDT ratios and lower proportions of trans-nonachlor to total chlordane components than reported for odontocetes living in more contaminated environments. Mean SigmaPCB concentrations in narwhal were 6- to 15-fold lower than in dolphins from the Canadian east coast and belugas from the St Lawrence River estuary, respectively, while PCC levels were from 4- to about 2-fold lower, and SigmaHCH, dieldrin and SigmaCBz differed by <2-fold. The pattern of organochlorines in narwhal tissues suggests they are exposed to proportionally more volatile compounds, and may have less capacity to metabolize some of these compounds, relative to odontocetes living nearer sources of these contaminants.