Air monitoring of polychlorinated biphenyls, polybrominated diphenyl ethers and organochlorine pesticides in West Antarctica during 2011-2017: Concentrations, temporal trends and potential sources

Trends in low temperature and non-thermal technologies for the degradation of persistent organic pollutants

The daunting effects of persistent organic pollutants on humans, animals, and the environment cannot be overemphasized. Their fate, persistence, long-range transport, and bioavailability have made them an environmental stressor of concern which has attracted the interest of the research community. Concerted efforts have been made by relevant organizations utilizing legislative laws to ban their production and get rid of them completely for the sake of public health. However, they have remained refractive in different compartments of the environment. Their bioavailability is majorly a function of different anthropogenic activities. Landfilling and incineration are among the earliest classical means of environmental remediation of waste; however, they are not sustainable due to the seepage of contaminants in landfills, the release of toxic gases into the atmosphere and energy requirements during incineration. Other advanced waste destruction technologies have been explored for the degradation of these recalcitrant pollutants; although, some are efficient, but are limited by high amounts of energy consumption, the use of organic solvents and hazardous chemicals, high capital and operational cost, and lack of public trust. Thus, this study has systematically reviewed different contaminant degradation technologies, their efficiency, and feasibility. Finally, based on techno-economic feasibility, non-invasiveness, efficiency, and environmental friendliness; radiation technology can be considered a viable alternative for the environmental remediation of contaminants in all environmental matrices at bench-, pilot-, and industrial-scale.

Health assessment of emerging persistent organic pollutants (POPs) in PM2.5 in northern and central Taiwan

Over the last two decades, Taiwan has effectively diminished atmospheric concentrations of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) through the adept utilization of advanced technologies and the implementation of air pollution control devices. Despite this success, there exists a dearth of data regarding the levels of other PM2.5-bound organic pollutants and their associated health risks. To address this gap, our study comprehensively investigates the spatial and seasonal variations, potential sources, and health risks of PCDD/Fs, Polychlorinated biphenyls (PCBs), and Polychlorinated naphthalene (PCNs) in Northern and Central Taiwan. Sampling collections were conducted at three specific locations, including six municipal waste incinerators in Northern Taiwan, as well as a traffic and an industrial site in Central Taiwan. As a result, the highest mean values of PM2.5 (20.3-39.6 μg/m3) were observed at traffic sites, followed by industrial sites (14.4-39.3 μg/m3), and the vicinity of the municipal waste incinerator (12.4-29.4 μg/m3). Additionally, PCDD/Fs and PCBs exhibited discernible seasonal fluctuations, displaying higher concentrations in winter (7.53-11.9 and 0.09-0.12 fg I-TEQWHO/m3) and spring (7.02-13.7 and 0.11-0.16 fg I-TEQWHO/m3) compared to summer and autumn. Conversely, PCNs displayed no significant seasonal variations, with peak values observed in winter (0.05-0.10 fg I-TEQWHO/m3) and spring (0.03-0.08 fg I-TEQWHO/m3). Utilizing a Positive Matrix Factorization (PMF) model, sintering plants emerged as the predominant contributors to PCDD/Fs, constituting 77.9% of emissions. Woodchip boilers (68.3%) and municipal waste incinerators (21.0%) were identified as primary contributors to PCBs, while municipal waste incinerators (64.6%) along with a secondary copper and a copper sludge smelter (22.1%) were the principal sources of PCNs. Moreover, the study specified that individuals aged 19-70 in Northern Taiwan and those under the age of 12 years in Central Taiwan were found to have a significantly higher cancer risk, with values ranging from 9.26 x 10-9-1.12 x 10-7 and from 2.50 x 10-8-2.08 x 10-7respectively.

Occurrence and diffusive air-seawater exchanges of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Fildes Bay, King George Island, Antarctica

We report the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in seawater and air, and the air-sea dynamics through diffusive exchange analysis in Fildes Bay, King George Island, Antarctica, between November 2019 and January 30, 2020. Hexachlorobenzene (HCB) was the most abundant compound in both air and seawater with concentrations around 39 ± 2.1 pg m-3 and 3.2 ± 2.4 pg L-1 respectively. The most abundant PCB congener was PCB 11, with a mean of 3.16 ± 3.7 pg m-3 in air and 2.0 ± 1.1 pg L-1 in seawater. The fugacity gradient estimated for the OCP compounds indicate a predominance of net atmospheric deposition for HCB, α-HCH, γ-HCH, 4,4'-DDT, 4,4'-DDE and close to equilibrium for the PeCB compound. The observed deposition of some OCs may be driven by high biodegradation rates and/or settling fluxes decreasing the concentration of these compounds in surface waters, which is supported by the capacity of microbial consortium to degrade some of these compounds. The estimated fugacity gradients for PCBs showed differences between congeners, with net volatilization predominating for PCB-9, a trend close to equilibrium for PCB congeners 11, 28, 52, 101, 118, 138, and 153, and deposition for PCB 180. Snow amplification may play an important role for less hydrophobic PCBs, with volatilization predominating after snow/glacier melting. As hydrophobicity increases, the biological pump decreases the concentration of PCBs in seawater, reversing the fugacity gradient to atmospheric deposition. This study highlights the potential impacts of climate change, through glacier retreat, on the biogeochemistry of POPs, remobilizing those compounds previously trapped within the cryosphere which in turn will transform the Antarctic cryosphere into a secondary source of the more volatile POPs in coastal areas, influenced by snow and ice melting.

Cross-regional scale studies of organochlorine pesticides in air in China: Pollution characteristic, seasonal variation, and gas/particle partitioning

Few simultaneous studies of organochlorine pesticides (OCPs) in the atmosphere have been conducted across Southeast and Northeast China, and no data on the gas/particle (G/P) partitioning behaviors of several current-use OCPs are available. In this study, a one-year synchronous monitoring program was conducted for OCPs in Chinese atmosphere spanning 30° latitude and 60 °C temperature. A total of 111 pairs of gas and particle samples were collected from Mohe and Harbin in Northeast China and from Shenzhen in Southeast China. The detection frequency for 66.7 % of the OCPs exceeded 80 %, indicating their prevalence in the atmosphere. The concentrations of individual OCPs spanned six orders of magnitude, indicating different pollution levels. Highest levels of hexachlorobenzene were observed at all sites. Banned OCPs were found predominantly in secondary distribution patterns, whereas current-use OCPs were dominated by primary distribution patterns. In Harbin and Mohe, the concentrations of OCPs were highest in summer, followed by autumn and winter. No obvious seasonal variation was observed in Shenzhen associated with different cultivation types. At all three sites, OCPs were predominantly found in the gas phase, and higher percentages of particle-phase OCPs were observed in Harbin and Mohe than in Shenzhen. In this study, G/P partitioning models were used to study the G/P partitioning mechanism of OCPs. The Li-Ma-Yang model provided the most accurate prediction of the G/P partitioning behavior of OCPs with high molecular weights and low vapor pressures, particularly at low temperatures. However, OCPs with lower molecular weights and higher vapor pressures were predominantly in the equilibrium state, for which the Junge-Pankow model was suitable. This systematic cross-scale study provides new insights into pollution, G/P partitioning, and the environmental behavior of OCPs in the atmosphere.

Dichlorodiphenyltrichloroethane (DDT) and Dichlorodiphenyldichloroethylene (DDE) levels in air and surface sea waters along the Antarctic Peninsula

Persistent organic pollutants (POPs) are widespread worldwide, even reaching polar regions. Among POPs, dichlorodiphenyltrichloroethane (DDT) and their metabolites have been reported scarcely in the Antarctic environment. Here we report the levels of p,p'-DDT, o,p'-DDT, p,p'-DDE, and o,p'-DDE in air and water samples collected during austral summer 2009. The levels found ranged from 0.25 to 4.26 pg m-3 in the atmospheric samples while in the water samples ranged from 0.07 to 0.25 pg L-1. These concentrations were within the range of the reported concentrations in the last 20 years in Antarctica. However, the source ratio showed that most of p,p'-DDT comes from fresh applications and Dicofol formulations. The back-trajectories estimated for the air masses revealed that most of the p,p'-DDT came from the continental Antarctic peninsula and surrounding waters. The diffusive exchange direction showed that Antarctic surface waters are the final sink of the studied compounds during the survey period.

Mobilization of persistent organic pollutants in humpback whales: Insights from feeding areas in the Antarctic peninsula and Strait of Magellan to migration, breeding, and calving grounds along the Brazilian coast

Southern Hemisphere Megaptera novaeangliae undertake the longest migration, which reflect their exposure to lipophilic contaminants. To assess these changes, persistent organic pollutants were analyzed in blubber samples of humpback whales from three regions: the Antarctic Peninsula (n = 46), the Strait of Magellan, Chile (n = 22), and the Brazilian coast (n = 38). The similarity in PCB and HCB levels between individuals from feeding grounds and breeding grounds suggests contamination during feeding. The whales around the Antarctic Peninsula exhibited a predominance of tetrachlorobiphenyl PCBs. Whales feeding in the Strait of Magellan showed a slight prevalence of 5Cl biphenyls, likely due to their consumption of subantarctic krill species as well as small fishes potentially contaminated by industrial activities in Chile. The dominance of 5-6Cl congeners in whales in Brazil, may be attributed to the extreme physiological changes during fasting when whales utilize blubber reserves and metabolize lighter congeners, or transfer them to their calves.

Source identification of PCBs in Antarctic air by compound-specific isotope analysis of chlorine (CSIA-Cl) using HRGC/HRMS

Occurrence of persistent organic pollutants (POPs) in the Polar Regions has received great concern in the past several decades due to their long-term adverse effect on biological health in such a fragile environment. However, there is still argument over their source and fate in these pristine areas. Here we attempted to use a novel approach (compound-specific isotope analysis of chlorine, CSIA-Cl) to identify the source of POPs in Antarctic air by comparison with the source area. The results showed that the relative isotope-ratio variation of Cl (δ³⁷Cl') values showed a large variation from - 137 to 9.04 ‰ in the gas-phase samples, and a significantly negative correlation (p < 0.01) was obtained against the logKoa values of PCBs. There were no significant correlations (p > 0.05) observed between the δ³⁷Cl' values and meteorological parameters except for PCB-28 which showed temperature dependence. By contrast, the δ³⁷Cl' values in the urban (Beijing) air ranged from - 12.8 to 2.03 ‰. The larger variation of δ³⁷Cl' in Antarctic air indicated evidently influence of long-range atmospheric transport (LRAT) on isotopologue fractionation of PCBs. This study may shed light on the application of CSIA-Cl for source identification of chlorinated POPs on a large scale.

Legacy and novel brominated flame retardants in air of Ny-Ålesund, Arctic from 2011 to 2019

Concentrations of polybrominated diphenyl ethers (PBDEs) and novel brominated flame retardants (NBFRs) in the atmosphere of Ny-Ålesund, Svalbard, were investigated. Passive air samples were collected for eight consecutive one-year periods from August 2011 to August 2019 at seven Arctic sampling sites. High-resolution gas chromatography coupled with high-resolution mass spectrometry (HRGC-HRMS) and gas chromatography coupled with election capture negative ionization mass spectrometry (GC-NCI-MS) were employed for PBDE and NBFR analysis, respectively. The median concentrations of Ʃ₁₁PBDEs and Ʃ₆NBFRs were 0.6 pg/m³ and 4.0 pg/m³, respectively. Hexabromobenzene and BDE-47 were the most abundant NBFR and PBDE congeners in the atmosphere, accounting for 31% and 24% of ƩNBFR and ƩPBDE concentrations, respectively. ƩNBFR concentration was approximately six times higher than that of ƩPBDEs in the same samples. Among NBFRs, the concentrations of 1,2,3,4,5-pentabromobenzene, 2,3,4,5,6-pentabromobenzene, and 2,3-dibromopropyl-2,4,6-tribromophenyl ether showed increasing temporal variations, with estimated doubling times of 3.0, 3.3, and 2.8 years, respectively. The concentrations of almost all PBDE congeners showed a decreasing variation, with halving times ranging from 2.1 to 9.5 years.

A Review of Polychlorinated Biphenyls (PCBs) Pollution in the Air: Where and How Much Are We Exposed to?

Polychlorinated biphenyls (PCBs) were widely used in industrial and commercial applications, until they were banned in the late 1970s as a result of their significant environmental pollution. PCBs in the environment gained scientific interest because of their persistence and the potential threats they pose to humans. Traditionally, human exposure to PCBs was linked to dietary ingestion. Inhalational exposure to these contaminants is often overlooked. This review discusses the occurrence and distribution of PCBs in environmental matrices and their associated health impacts. Severe PCB contamination levels have been reported in e-waste recycling areas. The occurrence of high PCB levels, notably in urban and industrial areas, might result from extensive PCB use and intensive human activity. Furthermore, PCB contamination in the indoor environment is ten-fold higher than outdoors, which may present expose risk for humans through the inhalation of contaminated air or through the ingestion of dust. In such settings, the inhalation route may contribute significantly to PCB exposure. The data on human health effects due to PCB inhalation are scarce. More epidemiological studies should be performed to investigate the inhalation dose and response mechanism and to evaluate the health risks. Further studies should also evaluate the health impact of prolonged low-concentration PCB exposure.

Novel brominated and organophosphate flame retardants in the atmosphere of Fildes Peninsula, West Antarctica: Continuous observations from 2011 to 2020

Novel brominated flame retardants (NBFRs) and organophosphate esters (OPEs) have been widely detected in various environmental matrices worldwide and raised public concerns in recent years. However, few studies reported their occurrence and temporal trend in Antarctic air. In this study, concentrations, distribution, and temporal trends of NBFRs and OPEs in the air of Fildes Peninsula, West Antarctica, were investigated using XAD resin-based passive air sampling from January 2011 to January 2020. Air concentrations of the total OPEs (Σ₇OPEs) were one to two orders of magnitude higher than those of the total NBFRs (Σ₆NBFRs). Decabromodiphenyl ethane and tris(2-chloroethyl) phosphate were the most abundant NBFR and OPE congeners, respectively. Significant positive correlations were observed among hexabromobenzene, pentabromoethylbenzene, and pentabromotoluene, indicating that their occurrence in Antarctic air may be affected by similar sources. No spatial differences in any of the NBFR and OPE congeners were observed, implying minor impact from local scientific research stations. Linear regression analysis was used to evaluate the temporal trends of NBFRs and OPEs in Antarctic air, with decreasing trends observed for Σ₆NBFRs and Σ₇OPEs. This is one of the rare studies providing a comprehensive investigation of the temporal trends in NBFRs and OPEs in Antarctic air and highlights concern regarding the contamination of these chemicals in remote polar regions.

Legacy and emerging organic contaminants in the polar regions

The presence of numerous emerging organic contaminants (EOCs) and remobilization of legacy persistent organic pollutants (POPs) in polar regions have become significant concerns of the scientific communities, public groups and stakeholders. This work reviews the occurrences of EOCs and POPs and their long-range environmental transport (LRET) processes via atmosphere and ocean currents from continental sources to polar regions. Concentrations of classic POPs have been systematically monitored in air at several Arctic stations and showed seasonal variations and declining trends. These chemicals were also the major POPs reported in the Antarctica, while their concentrations were lower than those in the Arctic, illustrating the combination of remoteness and lack of potential local sources for the Antarctica. EOCs were investigated in air, water, snow, ice and organisms in the Arctic. Data in the Antarctica are rare. Reemission of legacy POPs and EOCs accumulated in glaciers, sea ice and snow may alter the concentrations and amplify their effects in polar regions. Thus, future research will need to understand the various biogeochemical and geophysical processes under climate change and anthropogenic pressures.

Accumulations and temporal trends of polychlorinated biphenyls (PCBs) in olive tree components

In this study, ambient air samples, olive tree branches (1- and 2-year-old) and their leaves (particulate and dissolved phase) were collected simultaneously between January and December months at a suburban site of Bursa-Turkey. Total polychlorinated biphenyl (PCB) concentrations, sampled by employing passive air samplers, ranged from 0.03 to 0.08 ng/m³ in the atmosphere. The average annual total PCB concentrations belonging to the tree components were 1.14 ± 0.32 ng/g DM in dissolved phase in leaves, 0.71 ± 0.32 ng/g DM in particle phase on leaves, 1.06 ± 0.25 ng/g DM in 1-year-old branches, and 0.93 ± 0.23 ng/g DM in 2-year-old branches. It was determined that the correlation between PCB concentrations in olive tree components and the air was low. This result indicated that besides the tree-air exchange, other possible factors (such as soil-to-tree transitions, wind effect, etc.) affect the levels of PCB concentrations in the tree components. Total PCB concentrations decreased from summer to winter in all samples. The percentage ratio of PCB in the dissolved phase in the leaves was generally higher than other tree components in seasons. PCB homologous distributions indicated 5-CBs were dominant in the tree components and 3-CBs were dominant in the air samples. Highly chlorinated PCB congeners (8-CBs and 9-CBs) were found at low concentrations in both air and tree components samples. The samples indicated that the ratio of PCBs in tree components to the total (tree component+ambient air) PCBs slightly increased with increasing the chlorine number.

Changes and distribution of gas-phase polycyclic aromatic hydrocarbons and organochlorine compounds in a high-mountain gradient over a three-year period (Pyrenees, 2017-2020)

The atmospheric gas-phase concentrations of several polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene (HCB), and pentachlorobenzene (PeCB) were measured in six high-mountain sites in the Pyrenees (1619-2453 m). Polyurethane foam passive air samplers were used for this purpose, providing continuous records spanning over three years (2017-2020). The mean concentrations of ∑PCBs, HCB, and PeCB, 13 ± 4 pg m^-3, 44 ± 18 pg m^-3, and 23 ± 20 pg m^-3, respectively, were of the order of those reported in other mountain sites and similar to those measured 20 years ago in the same area, evidencing the persistence of these compounds despite the international regulatory actions. The mean concentration of ∑PAHs was 631 ± 238 pg m^-3, representing between two- and three-times lower values than 20 years ago in the same area, but still in the range of other mountain regions. Statistically significant increases in gas-phase concentrations at higher temperatures were observed for most compounds. The experimental phase-change pseudo-enthalpies calculated from the slopes of the regressions between the natural logarithm of the concentrations and the reciprocal of temperature were lower than the reference values for nearly all compounds. This difference suggested a main contribution of long-range atmospheric transport of the gas-phase PAH and organochlorine concentrations in this mountain area. However, the less volatile compounds such as benz[a]anthracene, PCB138, and PCB180 showed a closer similarity between experimental and laboratory enthalpies, indicating that a significant portion of the variations in concentration of these compounds originated from temperature-dependent diffusive exchange by re-volatilization from local surfaces. The concentrations found in these sentinel ecosystems demonstrate that long-range transport of organic pollutants remains a risk in remote continental environments.

Organochlorine pesticides and polychlorinated biphenyls in high mountain lakes, Mexico

Pollution levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the El Sol and the La Luna alpine lakes. The lakes are located in central Mexico, in the crater of the Nevado de Toluca volcano. The El Sol and the La Luna lakes are extremely relevant in Mexico and in the world because they are recognized as pristine regions and environmental reservoirs. Samples of atmospheric aerosol, sediment, plankton, and Tubifex tubifex (sludge worm) were collected at three different sample locations for three years (2017, 2018, and 2019) at three different times of year, meaning that the weather conditions at the time of sampling were different. Pollutants were analysed by gas chromatography-mass spectrometry with negative chemical ionisation (GC-MS/NCI). Endosulfan was the most frequent and abundant pollutant, showing the highest peaks of all. Atmospheric aerosol revealed Σ₂ = 45 pg/m³, including α and β, while sediment lakes displayed α, β and endosulfan sulfate as Σ₃ = 1963 pg/g, whereas plankton and Tubifex tubifex showed Σ₂ = 576 pg/g and 540 pg/g for α and β respectively. Results of endosulfan ratios (α/β) and (α-β/endosulfan sulfate) suggest that both fresh and old discharges continue to arrive at the lakes. This study shows for the first time the pollution levels of OCP and PCB in high mountain lakes in Mexico. These results that must be considered by policy makers to mitigate their use in the various productive activities of the region.

Characteristics of PAHs, PCDD/Fs, PCBs and PCNs in atmospheric fine particulate matter in Dalian, China

Organic species in fine particulate matter (PM_2.5) may exhibit significant health risks. The level, composition and sources of PM_2.5-bound organic pollutants are temporally and spatially highly variable. In this study, the pollution characteristics and health risks of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs) and polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) in PM_2.5 of Dalian were investigated. PM_2.5-bound organic pollutants in Dalian were generally lower than other regions in China and other countries, significant seasonal changes were observed, higher levels appeared in winter than in summer. Concentrations of 16 PAHs were 2.07 ng/m³ and 13.99 ng/m³ in summer and winter, respectively. PAHs with 4-ring and 5-ring were the dominant components. Diagnostic analysis and principal component analysis (PCA) indicated that PAHs mainly originate from petroleum emissions and combustion. Concentrations of PCDD/Fs, PCBs and PCNs in PM_2.5 ranged from 0.05 to 3.27, 0.04-0.65 and 0.05-1.42 pg/m³, respectively. PCDD/Fs and PCBs were mainly consisted of high-chlorinated homologues during the sampling period. High-chlorinated PCNs were dominated only in winter, while low-chlorinated PCNs were dominated in summer, industrial thermal activity was one of the main sources of PCNs. The high correlation coefficients of the concentration of PAHs, PCBs, PCNs, and PCDD/Fs with that of SO₂ indicated that combustion sources contributed more to PM_2.5-bound organic pollutants than that of motor vehicle emissions. The incremental lifetime cancer risk induced by PM_2.5-bound POPs is relatively lower in Dalian than other regions.

Seasonal variations in air concentrations of 27 organochlorine pesticides (OCPs) and 25 current-use pesticides (CUPs) across three agricultural areas of South Africa

For decades pesticides have been used in agriculture, however, the occurrence of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) is poorly understood in Africa. This study investigates air concentrations of OCPs and CUPs in three South African agricultural areas, their spatial/seasonal variations and mixture profiles. Between 2017 and 2018, 54 polyurethane foam-disks passive air-samplers (PUF-PAS) were positioned in three agricultural areas of the Western Cape, producing mainly apples, table grapes and wheat. Within areas, 25 CUPs were measured at two sites (farm and village), and 27 OCPs at one site (farm). Kruskal-Wallis tests investigated area differences in OCPs concentrations, and linear mixed-effect models studied differences in CUPs concentrations between areas, sites and sampling rounds. In total, 20 OCPs and 16 CUPs were detected. A median of 16 OCPs and 10 CUPs were detected per sample, making a total of 11 OCPs and 24 CUPs combinations. Eight OCPs (trans-chlordane, o,p'-/p,p'-dichlorodiphenyldichloroethylene (DDE)/dichlorodiphenyltrichloroethane (DDT), endosulfan sulfate, γ-hexachlorocyclohexane and mirex) and two CUPs (carbaryl and chlorpyrifos) were quantified in all samples. p,p'-DDE (median 0.14 ng/m³) and chlorpyrifos (median 0.70 ng/m³) showed the highest concentrations throughout the study. Several OCPs and CUPs showed different concentrations between areas and seasons, although CUPs concentrations did not differ between sites. OCPs ratios suggest ongoing chlordane use in the region, while DDT and endosulfan contamination result from past-use. Our study revealed spatial and seasonal variations of different OCPs and CUPs combinations detected in air. Further studies are needed to investigate the potential cumulative or synergistic risks of the detected pesticides.

Tracking POPs in Global Air from the First 10 Years of the GAPS Network (2005 to 2014)

The Global Atmospheric Passive Sampling (GAPS) network, initiated in 2005 across 55 global sites, supports the global monitoring plan (GMP) of the Stockholm Convention on Persistent Organic Pollutants (POPs) by providing information on POP concentrations in air on a global scale. These data inform assessments of the long-range transport potential of POPs and the effectiveness evaluation of chemical regulation efforts, by observing changes in concentrations over time. Currently, measurements spanning 5-10 sampling years are available for 40 sites from the GAPS Network. This study was the first time that POP concentrations in air were reported on a global scale for an extended time period and the first to evaluate worldwide trends with an internally consistent sample set. For consistency between sampling years, site- and sample specific sampling rates were calculated with a new, public online model, which accounts for the effects of wind speed variability. Concentrations for legacy POPs in air between 2005 and 2014 show different trends for different organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The POPs discussed in this study were chosen due to being the most frequently detected, with detection at the majority of sites. PCB, endosulfan, and hexachlorocyclohexane (HCH) concentrations in air are decreasing at most sites. The global trends reflect global sources and recycling of HCH, ongoing emissions from old stockpiles for PCBs, and recent use restrictions for endosulfan. These chlorinated OCPs continue to present exposure threat to humans and ecosystems worldwide. Concentrations of other OCPs, such as chlordanes, heptachlor and dieldrin, are steady and/or declining slowly at the majority of sites, reflecting a transition from primary to secondary sources (i.e., re-emission from reservoirs where these POPs have accumulated historically) which now control ambient air burdens.

Organochlorine pesticides in honeybee, pollen and honey in Bursa, Turkey

g-In this study, the presence of OCP residues in the honeybee, pollen and honey samples in urban and semi-urban areas were investigated. A total of 10 OCP concentrations (∑₁₀OCP) in honeybee samples were 39.14 ± 11.06 ng g^-1 for the urban area and 39.93 ± 7.09 ng g^-1 for the semi-urban area, respectively. Similarly, ∑₁₀OCP concentrations in pollen and honey samples were estimated to be 21.72 ± 4.43 ng g^-1 and 41.83 ± 1.61 ng g^-1 for the urban area, 19.77 ± 2.86 ng g^-1 and 39.23 ± 3.90 ng g^-1 for the semi-urban area, respectively. Also, it was concluded that the existence of OCP residues in both sampling areas was due to the recent use of pesticides. Finally, the cancer risk caused by the consumption of pollen and honey samples was evaluated, and it was found that there was no cancer risk in both sampling areas.

Sources of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) found in surface sediment from coastal areas of Beibu Gulf: A reflection on shipping activities and coastal industries

The presence of polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs) was determined in the sediments of Beibu Gulf, a newly developing industry and port in South China, to evaluate whether the rapid development of coastal cities has accelerated the organic pollution in the region. The levels of PCBs and DDTs ranged from 1.17 to 8.00 ng g^-1 and ND (not detected) to 3.82 ng g^-1, respectively. The levels were higher in the east of Beibu Gulf than in the west, which influenced by the industrialisation and urbanisation in the east. Additionally, penta-PCBs were the dominant PCB congeners, which are related to shipping activities, and DDTs may have originated from the historical use of technical DDT. The levels of pp'-DDD and PCBs did not have the potential to cause ecological risks in Beibu Gulf; however, residues of DDTs were at relatively higher ecotoxicological levels, thereby having the potential to cause adverse biological effects.

Atmospheric concentrations and temporal trends of polychlorinated biphenyls and organochlorine pesticides in the Arctic during 2011-2018

Passive air samples were deployed in Ny-Ålesund and London Island (Svalbard, High Arctic) annually for seven years (2011-2018) to investigate concentrations, temporal trends and potential sources of selected persistent organic pollutants (POPs). Nine polychlorinated biphenyls and twelve organochlorine pesticides were detected in all samples, with 3,3'-dichlorobiphenyl (PCB-11) being the prevalent congener. Concentrations of most compounds were declining. The ratio of the α- and γ-isomer of hexachlorocyclohexane (HCH) in Arctic air was comparable with that in technical HCH mixtures, but higher than that in the atmosphere of other countries, thereby indicating the impact of historical use as well as the possible photoisomerization of the γ- into the α-isomer. The parent dichlorodiphenyltrichloroethane (DDT) was always less abundant than its degradation products dichlorodiphenylethylene (DDE), indicative of the impact of aged DDT sources in the Arctic atmosphere. However, o,p'-/p,p'-DDT ratios suggest only a minor contribution of dicofol-type DDT. A slightly declining temporal trend of the trans-chlordane/cis-chlordane ratio indicated the impact of secondary sources. The atmospheric distribution of the investigated POPs in the Arctic was mainly attributed to long-range atmospheric transport, whereas the influence of human activities from the scientific research stations was minor.

Spatial distribution of cumulative impact on terrestrial ecosystem of the Fildes Peninsula, Antarctica

Antarctica, an area that is devoted to global peace and research, is being challenged by climate change, human activities, and pollution. There have been a number of studies concerning the state of the Antarctic ecological environment. However, a comprehensive and quantitative assessment of the impact of threats on the Antarctica ecological environment is still lacking. In this study, a cumulative impact assessment performed on the basis of expert judgement was used to estimate species-specific differences on the impact of seven threats: climate change, organic and nonorganic pollutants, station construction, power generation, oil spilling, and tourism. The terrestrial area of the Fildes Peninsula was divided into 103 cells using a raster grid of 0.25 km², and cumulative impact assessment was applied to each cell. The analysis results indicated that cumulative impact scores (I_C) ranged from 0 to 39.4, and the cumulative scores were divided into six categories ranging from very low impact (I_C ≤ 7.08) to very high impact (I_C > 20.54). More than half of the terrestrial area (57.3%) experienced "Very Low Impact" or "Low impact" scores. For single factors, climate change was identified as a rapidly growing and significant threat facing the terrestrial ecosystems of Antarctica. In addition, tourism had the greatest impact among all human activities. The analytical process and resulting map indicate that it is necessary to develop international policies on the restriction of tourist activity space and strength the organic pollutant controls for terrestrial ecosystem protection in the Fildes Peninsula, Antarctica.

4-Ethylphenol, A Volatile Organic Compound Produced by Disease-Resistant Soybean, Is a Potential Botanical Agrochemical Against Oomycetes

Oomycetes, represented by Phytophthora, are seriously harmful to agricultural production, resulting in a decline in grain quality and agricultural products and causing great economic losses. Integrated management of oomycete diseases is becoming more challenging, and plant derivatives represent effective alternatives to synthetic chemicals as novel crop protection solutions. Biologically active secondary metabolites are rapidly synthesized and released by plants in response to biotic stress caused by herbivores or insects, as well as pathogens. In this study, we identified groups of volatile organic compounds (VOCs) from soybean plants inoculated with Phytophthora sojae, the causal agent of soybean root rot. 4-Ethylphenol was present among the identified VOCs and was induced in the incompatible interaction between the plants and the pathogen. 4-Ethylphenol inhibited the growth of P. sojae and Phytophthora nicotianae and had toxicity to sporangia formation and zoospore germination by destroying the pathogen cell membrane; it had a good control effect on soybean root rot and tobacco black shank in the safe concentration range. Furthermore, 4-Ethylphenol had a potent antifungal activity against three soil-borne phytopathogenic fungi, Rhizoctonia solani, Fusarium graminearum, and Gaeumannomyces graminis var tritici, and four forma specialis of Fusarium oxysporum, which suggest a potential to be an eco-friendly biological control agent.

Passive air sampling for semi-volatile organic chemicals

During passive air sampling, the amount of a chemical taken up in a sorbent from the air without the help of a pump is quantified and converted into an air concentration. In an equilibrium sampler, this conversion requires a thermodynamic parameter, the equilibrium sorption coefficient between gas-phase and sorbent. In a kinetic sampler, a time-averaged air concentration is obtained using a sampling rate, which is a kinetic parameter. Design requirements for kinetic and equilibrium sampling conflict with each other. The volatility of semi-volatile organic compounds (SVOCs) varies over five orders of magnitude, which implies that passive air samplers are inevitably kinetic samplers for less volatile SVOCs and equilibrium samplers for more volatile SVOCs. Therefore, most currently used passive sampler designs for SVOCs are a compromise that requires the consideration of both a thermodynamic and a kinetic parameter. Their quantitative interpretation depends on assumptions that are rarely fulfilled, and on input parameters, that are often only known with high uncertainty. Kinetic passive air sampling for SVOCs is also challenging because their typically very low atmospheric concentrations necessitate relatively high sampling rates that can only be achieved without the use of diffusive barriers. This in turn renders sampling rates dependent on wind conditions and therefore highly variable. Despite the overall high uncertainty arising from these challenges, passive air samplers for SVOCs have valuable roles to play in recording (i) spatial concentration variability at scales ranging from a few centimeters to tens of thousands of kilometers, (ii) long-term trends, (iii) air contamination in remote and inaccessible locations and (iv) indoor inhalation exposure. Going forward, thermal desorption of sorbents may lower the detection limits for some SVOCs to an extent that the use of diffusive barriers in the kinetic sampling of SVOCs becomes feasible, which is a prerequisite to decreasing the uncertainty of sampling rates. If the thermally stable sorbent additionally has a high sorptive capacity, it may be possible to design true kinetic samplers for most SVOCs. In the meantime, the passive air sampling community would benefit from being more transparent by rigorously quantifying and explicitly reporting uncertainty.

Atmospheric concentration, source identification, and health risk assessment of persistent organic pollutants (POPs) in two countries: Peru and Turkey

It is known that some persistent organic pollutants (POPs) are used worldwide, and these pollutants are dangerous for human health. However, there are still countries where measurements of these pollutants have not been adequately measured. Although many studies have been published for determining the concentrations of POPs in Turkey, there are limited studies in Latin American countries like Peru. For this reason, it is essential both to conduct a study in Peru and to compare the study with another country. This study is aimed at determining the atmospheric POPs such as polycyclic aromatic hydrocarbon (PAH), organochlorine pesticide (OCP), and polychlorinated biphenyl (PCB) concentrations using passive air samplers in Yurimaguas (Peru) and Bursa (Turkey). Molecular diagnosis ratios and ring distribution methods were used to determine the sources of PAHs. According to these methods, coal and biomass combustions were among the primary sources of PAHs in Peru, while petrogenic and petroleum were the primary sources of PAHs in Turkey. Then, α-HCH/γ-HCH and β-/(α+γ)-HCH ratios were used to determine the sources of OCPs. According to the α-HCH/γ-HCH ratios, the primary sources of OCPs in both countries were lindane. Similarly, according to β-/(α+γ)-HCH ratios, the HCHs have been historically used in Peru while they were recently utilized in Turkey. Finally, homologous group distributions were used to determine the sources of PCBs. Similar distributions of homologous groups were observed in the sampling sites in both countries. Also, the homologous group distributions obtained have been determined that industrial activities could be effective in the sampling areas in both countries. When the cancer risks that could occur via inhalation were evaluated, no significant cancer risk has been determined in both countries.

Occurrence and distribution of organophosphate esters in the air and soils of Ny-Ålesund and London Island, Svalbard, Arctic

The levels of eight organophosphate esters (OPEs) were analyzed in air and soil samples collected at Ny-Ålesund and London Island, Svalbard during the Chinese Scientific Research Expedition to the Arctic during 2014-2015. The concentrations of total OPEs (∑OPEs) ranged from 357 pg/m³ to 852 pg/m³ in the air and from 1.33 ng/g to 17.5 ng/g dry weight (dw) in the soils. Non-Cl OPEs accounted for 56 ± 13% and 62 ± 16% of ∑OPEs for the air and soil, respectively. Tris(2-chloroethyl) phosphate (TCEP) was the dominant compound in the air, with an average concentration of 180 ± 122 pg/m³. Triphenyl phosphate, tri(1-chloro-2-propyl) phosphate, and TCEP were the most abundant OPEs in the soils, with mean values of 1.77, 2.13, and 1.02 ng/g dw, respectively. Compared with the levels of polybrominated diphenyl ethers found in Arctic regions in previous studies, OPEs showed significantly higher concentrations, thereby indicating the large production and wide usage of OPEs globally. In addition, the fugacity fraction results indicated that net deposition from air to soil was dominated in the area. Overall, the occurrence and distribution of OPEs in the air and soils in the Arctic region indicated that OPEs can undergo long-range atmospheric transport and accumulate in remote regions.

Atmospheric legacy organochlorine pesticides and their recent exchange dynamics in the Northwest Pacific Ocean

The occurrence and air-sea gas exchange of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), and chlordanes were determined in the Northwest Pacific Ocean (NWP) in spring to elucidate their current pollution status and fate. ΣHCHs, ΣDDTs, and Σchlordanes in air (sum of gaseous and aerosol phase) ranged from 9.37 to 102, from 1.73 to 12.8, and from 0.24 to 14.9 pg/m³, respectively, with their dissolved levels being 30.7-518, 7.10-80.5, and 0.25-7.10 pg/L, respectively. HCHs, DDTs, and chlordanes cause substantial contamination of the air and seawater of the East China Sea (ECS), indicating significant OCP inputs from China. Isomer ratios of HCHs and DDTs provided a fingerprint of East Asian emissions of legacy OCPs, with the pollution profiles of HCHs and DDTs dominated by lindane and combined dicofol-type and weathered technical DDTs, respectively. The former result is consistent with the apparent decline in air α-HCH levels over the ECS. Different from still net deposition of gaseous α- and γ-HCH in the NWP, outgassing of trans-chlordane, cis-chlordane, and DDTs other than dicofol-sourced o,p'-DDT was indicated. This observation attributes to intensive historical usage of technical HCHs and the prevalence of lindane pollution in East Asia, and demonstrates the transitioning role of seawater as a source for residual OCPs in the East Asia-NWP region. Significant subcooled liquid vapor pressure-based relationships for legacy OCPs were identified mainly in marine air masses; these were different from land-sourced polybrominated diphenyl ethers, and suggested a heterogeneous role of ocean- and land-based sources in atmospheric partitioning of these pollutants.

Occurrence and sources of polycyclic aromatic hydrocarbons in atmosphere and soil from 2013 to 2019 in the Fildes Peninsula, Antarctica

Long-term monitoring is essential for revealing pollution trends, but relevant studies in the Antarctic remain limited. In this study, a seven-year continuous monitoring of polycyclic aromatic hydrocarbons (PAHs) in the atmosphere and soil was carried out at the Fildes Peninsula, Antarctica. Average concentrations of Σ₁₅PAHs were 7134.491 pg/m³ and 61.093 ng/g in air and soil, respectively. A declining trend was observed for Σ₁₅PAHs in air during the 2013-2019 summer, but this was not found in soil. Potential sources of PAHs in the Fildes Peninsula were identified by PMF modeling, correlation analysis, air mass back-trajectories and component analysis. The results showed that PAHs in the gas phase were more easily influenced by long-range atmospheric transport (LRAT) than in the particle phase. Moreover, temperature played a key role in the PAHs concentration in particle phase. Occurrence of Σ₁₅PAHs in soil was mainly attributed to local sources including fossil fuel combustion and spilling.

Adélie penguin colonies as indicators of brominated flame retardants (BFRs) in East Antarctica

While persistent organic pollutant (POP) contamination within Antarctica is largely caused by long-range atmospheric transport (LRAT), Antarctic research bases have been shown to be local sources of POPs such as brominated flame retardants (BFRs). This study compared concentrations of seven polybrominated diphenyl ethers (PBDE) congeners and five novel flame retardants (NBFRs) found in Adélie penguin (Pygoscelis adeliae) colony soils near the Australian research stations, Mawson and Davis, to assess the stations as local sources of these contaminants and provide a much needed baseline for contamination of BFRs in East Antarctica. Soil samples (n = 46) were collected from Adélie colonies at close proximity to the research stations as well as further afield during the 2016-17 austral summer. Samples were analysed using selective pressurised liquid extraction (S-PLE) and gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). PBDEs (BDE-28, -47, -99, -100, -153, -154 and -183) were detected in 45/46 samples with ∑₇PBDE concentrations ranging from <0.01 to 1.63 ng/g dry weight (dw) and NBFRs (2,3,4,5,6-pentabromotoluene (PBT), 2,3,4,5,6-pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis(2,4,6-tribromophenoxy) ethane (BTBPE)) detected in 20/46 samples, with a range of ∑₅NBFR from not detected (ND) to 0.16 ng/g dw. Soils taken from around the Davis and Mawson research stations were more highly contaminated (n = 10) than penguin colonies (n = 27) and control areas not affiliated with breeding seabirds (n = 8). The most common congener detected was BDE-99, reflecting inputs from LRAT. However, the congener profiles of station soils supported the hypothesis that research stations are a local source of PBDEs to the Antarctic environment. In addition, the NBFR pentabromoethylbenzene (PBEB) was quantified for the first time in Antarctic soils, providing essential information for baseline contamination within the region and highlighting the need for ongoing monitoring as global regulations for the use of BFRs continuously change.

Trends of production, consumption and environmental emissions of Decabromodiphenyl ether in mainland China

Decabromodiphenyl ether (DecaBDE) is a brominated flame retardant belonging to the group of polybrominated diphenyl ethers. DecaBDE has been widely used for various applications, such as plastics, textiles, and building and construction materials. Limited information on DecaBDE production and usage inventory has been elaborated, however. Therefore, this work aimed to produce a preliminary emissions inventory of DecaBDE in mainland China by estimating production and consumption amounts of DecaBDE, and characterizing its emission factors during production and usage, based on industrial investigation and theoretical prediction. It was indicated that the total production of DecaBDE reached 464.68 thousand metric tons (kt), of which 62.72 kt were exported, since the beginning of its production. Shandong and Jiangsu provinces dominate the production, with proportions of 77.95% and 18.45%, respectively. The production stage releases most of the DecaBDE to the atmosphere, with an emissions factor of 23 ± 1.9 kg/t, followed by 20 ± 0.9 kg/t DecaBDE to waste water and 16 ± 1.0 kg/t DecaBDE as solid residue. DecaBDE emissions in the consumption stage-namely the plastic production process-are 0.17 ± 0.06-0.23 ± 0.08 kg DecaBDE to the atmosphere and 1.72 ± 0.58-2.29 ± 0.77 kg DecaBDE to solid residue, for each metric ton of plastic produced. The total annual DecaBDE emissions to waste water are 93.98-1140.9 mg-negligible. The results showed that the sources of DecaBDE environmental pollution are its manufacturing and flame-retardant plastic modification plants, which are easily overlooked by both the government and the public. Yet DecaBDE emissions elimination and the environmentally sound management of the DecaBDE waste generated from these two processes are crucial for environmental protection.

Assessing microbial degradation degree and bioavailability of BDE-153 in natural wetland soils: Implication by compound-specific stable isotope analysis

Microbial degradation is an important pathway for the attenuation of polybrominated diphenyl ethers (PBDEs) in natural soils. In this study, the compound-specific stable isotope analysis (CSIA) was applied to characterize microbial degradation of BDE-153, one of the prevailing and toxic PBDE congeners, in natural wetland soils. During the 45-day incubation, the residual percentages of BDE-153 decreased to 67.9% and 73.6% in non-sterilized soils spiked with 1.0 and 5.0 μg/g, respectively, which were both much lower than those in sterilized soils (96.0% and 97.2%). This result indicated that microbial degradation could accelerate BDE-153 elimination in wetland soils. Meanwhile, the significant carbon isotope fractionation was observed in non-sterilized soils, with δ¹³C of BDE-153 shifting from -29.4‰ to -26.7‰ for 1.0 μg/g and to -27.2‰ for 5.0 μg/g, respectively, whilst not in sterilized soils. This phenomenon indicated microbial degradation could induce stable carbon isotope fractionation of BDE-153. The carbon isotope enrichment factor (ε_c) for BDE-153 microbial degradation was first determined as -7.58‰, which could be used to assess the microbial degradation and bioavailability of BDE-153 in wetland soils. Based on δ¹³C and ε_c, the new methods were developed to dynamically and quantitatively estimate degradation degree and bioavailability of BDE-153 during degradation process, respectively, which could exclude interference of physical processes. This work revealed that CSIA was a promising method to investigate in situ microbial degradation of PBDEs in field studies.