On the mechanism of mountain cold-trapping of organic chemicals

Chronological distribution and potential sources of persistent toxic substances in soils from the glacier foreland of Midtre Lovénbreen, Svalbard

Despite its reputation as one of the cleanest regions globally, recent studies have identified the presence of various persistent toxic substances (PTSs) in the environmental matrices collected from Svalbard. This study investigated the chronological distribution and potential sources of 81 PTSs in soils from the glacier foreland of Midtre Lovénbreen. Soil samples (n = 45) were categorized by age based on exposure to the atmosphere due to glacier retreat in July 2014 into five age groups: 80-100 years (n = 7), 60-80 years (n = 12), 40-60 years (n = 16), 20-40 years (n = 7), and <20 years (n = 3). Concentrations of polychlorinated biphenyls (PCBs, n = 32) in soils varied with age, ranging from 0.29 to 0.74 ng g-1 dw. In addition, the concentrations of polycyclic aromatic hydrocarbons (PAHs, n = 28), perylene, and alkyl-PAHs (n = 20) in soils ranged from 21 to 80 ng g-1 dw, 2.9-62 ng g-1 dw, and 73-420 ng g-1 dw, respectively. The concentrations of PTSs were observed to be greater in older soils. Principal component analysis revealed that PCBs in soils originated from various product sources. Positive matrix factorization modeling estimated the association of PAHs in soils with potential origins, such as diesel emissions, petroleum and coal combustion, and coal. Potential sources of PAHs were mainly coal in younger soils and diesel emissions and petroleum combustion in older soils. Alkyl-PAH compositions in the soil were similar to those of bituminous coal, with a noteworthy degree of weathering observed in older soils. The accumulation rate and flux of PTSs in soils exhibited compound-specific patterns, reflecting factors such as long-range transport, fate, origin, and recent inputs. These findings can serve as baseline data for protecting and preserving polar environments.

Soil's Hidden Power: The Stable Soil Organic Carbon Pool Controls the Burden of Persistent Organic Pollutants in Background Soils

Persistent organic pollutants (POPs) tend to accumulate in cold regions by cold condensation and global distillation. Soil organic matter is the main storage compartment for POPs in terrestrial ecosystems due to deposition and repeated air-surface exchange processes. Here, physicochemical properties and environmental factors were investigated for their role in influencing POPs accumulation in soils of the Tibetan Plateau and Antarctic and Arctic regions. The results showed that the soil burden of most POPs was closely coupled to stable mineral-associated organic carbon (MAOC). Combining the proportion of MAOC and physicochemical properties can explain much of the soil distribution characteristics of the POPs. The background levels of POPs were estimated in conjunction with the global soil database. It led to the proposition that the stable soil carbon pools are key controlling factors affecting the ultimate global distribution of POPs, so that the dynamic cycling of soil carbon acts to counteract the cold-trapping effects. In the future, soil carbon pool composition should be fully considered in a multimedia environmental model of POPs, and the risk of secondary release of POPs in soils under conditions such as climate change can be further assessed with soil organic carbon models.

Alps at risk: High-mountain lakes as reservoirs of persistent and emerging contaminants

Despite their remote locations, high-mountain lakes located in the Alps are vulnerable to chemical pollution. This discussion explores the important aspects of these lakes as repositories of Persistent Organic Pollutants (POPs) and Contaminants of Emerging Concern (CECs), elucidating their sources and implications for both the environment and human health. In terms of the presence of POPs in high-altitude lakes of the Alps, 14 studies have been identified examining the occurrence of polychlorinated biphenyls, dichlorodiphenyltrichloroethane an its metabolites, polybrominated diphenyl ethers, and polycyclic aromatic hydrocarbons. The bulk of research on POPs in high-mountain lakes is concentrated in the Italian Alps (63%), followed by Switzerland (22%), Austria (12%), and France (3%), respectively. Sediment is predominantly investigated (65%), followed by fish (33%) and water (2%). Similarly, in relation to the presence of CECs in high-mountain lakes of the Alps, six studies have been identified investigating the occurrence of musks, perfluorinated compounds, and microplastics. Investigations into CECs predominantly occur in Switzerland (42%), France (33%), and Italy (25%), with fish samples (muscle and liver) being the primary focus (46%), followed by sediment (17%) and water (17%). Other compartments like zooplankton, frog/tadpoles, and snow remain less explored. The discussion also shed light on various pathways through which pollutants reach these remote landscapes, including atmospheric transport, glacial meltwater, and human activities. Protecting these pristine peaks demands concerted efforts encompassing ongoing research, vigilant monitoring, and dedicated conservation initiatives.

The transport and distribution of novel brominated flame retardants (NBFRs) and organophosphate esters (OPEs) in soils and moss along mountain valleys in the Himalayas

Although the Himalayas act as a natural barrier, studies have demonstrated that certain traditional persistent organic pollutants (POPs) can be transported into the Tibetan Plateau (TP) through the mountain valleys. Herein, we selected five mountain valleys in the Himalayas to investigate novel flame retardants (NFRs), as representative novel POPs, their concentration, distribution, transport behavior, potential sources and ecological risk. The results revealed that total concentrations of 7 novel brominated flame retardants (NBFRs) ranged from 4.89 to 2853 pg/g dry weight (dw) in soil and from not detected (ND) to 4232 pg/g dw in moss. Additionally, total concentrations of 10 organophosphate esters (OPEs) ranged from ND to 84798 pg/g dw in soil. Among the NFRs, decabromodiphenylethane (DBDPE) and tri-phenyl phosphate (TPhP) were the predominant compounds. NBFRs and OPEs concentrations were slightly higher than those in the polar regions. The correlation between different compounds and altitude varies in different areas, indicating that the NFRs distribution in the mountain valleys result from a combination of long-range transport and local sources. The ecological risk assessment using risk quotient (RQs) revealed that TPhP and tris (2-chloroisopropyl) phosphate (TCIPP) exhibited medium or high risks at some sites. This study sheds light on the transport pathways and environmental behaviors of the NFRs in the valleys and highlights the need for increased attention to the ecological risks posed by OPEs in the TP.

Sampling efficiency of a polyurethane foam air sampler: Effect of temperature

Effective monitoring of atmospheric concentrations is vital for assessing the Stockholm Convention's effectiveness on persistent organic pollutants (POPs). This task, particularly challenging in polar regions due to low air concentrations and temperature fluctuations, requires robust sampling techniques. Furthermore, the influence of temperature on the sampling efficiency of polyurethane foam discs remains unclear. Here we employ a flow-through sampling (FTS) column coupled with an active pump to collect air samples at varying temperatures. We delved into breakthrough profiles of key pollutants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), and organochlorine pesticides (OCPs), and examined the temperature-dependent behaviors of the theoretical plate number (N) and breakthrough volume (VB) using frontal chromatography theory. Our findings reveal a significant relationship between temperature dependence coefficients (KTN, KTV) and compound volatility, with decreasing values as volatility increases. While distinct trends are noted for PAHs, PCBs, and OCPs in KTN, KTV values exhibit similar patterns across all chemicals. Moreover, we establish a binary linear correlation between log (VB/m3), 1/(T/K), and N, simplifying breakthrough level estimation by enabling easy conversion between N and VB. Finally, an empirical linear solvation energy relationship incorporating a temperature term is developed, yielding satisfactory results for N at various temperatures. This approach holds the potential to rectify temperature-related effects and loss rates in historical data from long-term monitoring networks, benefiting polar and remote regions.

Persistent organic pollutants in global surface soils: Distributions and fractionations

The distribution and fractionation of persistent organic pollutants (POPs) in different matrices refer to how these pollutants are dispersed and separated within various environmental compartments. This is a significant study area as it helps us understand the transport efficiencies and long-range transport potentials of POPs to enter remote areas, particularly polar regions. This study provides a comprehensive review of the progress in understanding the distribution and fractionation of POPs. We focus on the contributions of four intermedia processes (dry and wet depositions for gaseous and particulate POPs) and determine their transfer between air and soil. These processes are controlled by their partitioning between gaseous and particulate phases in the atmosphere. The distribution patterns and fractionations can be categorized into primary and secondary types. Equations are developed to quantificationally study the primary and secondary distributions and fractionations of POPs. The analysis results suggest that the transfer of low molecular weight (LMW) POPs from air to soil is mainly through gas diffusion and particle deposition, whereas high molecular weight (HMW) POPs are mainly via particle deposition. HMW-POPs tend to be trapped near the source, whereas LMW-POPs are more prone to undergo long-range atmospheric transport. This crucial distinction elucidates the primary reason behind their temperature-independent primary fractionation. However, the secondary distribution and fractionation can only be observed along a temperature gradient, such as latitudinal or altitudinal transects. An animation is produced by a one-dimensional transport model to simulate conceptively the transport of CB-28 and CB-180, revealing the similarities and differences between the primary and secondary distributions and fractionations. We suggest that the decreasing temperature trend along latitudes is not the major reason for POPs to be fractionated into the polar ecosystems, but drives the longer-term accumulation of POPs in cold climates or polar cold trapping.

The occurrence and sources of PAHs, oxygenated PAHs (OPAHs), and nitrated PAHs (NPAHs) in soil and vegetation from the Antarctic, Arctic, and Tibetan Plateau

Although the fate of PAHs in the three polar regions (Antarctic, Arctic, and Tibetan Plateau) has been investigated, the occurrence and contamination profiles of PAH derivatives such as oxygenated PAHs (OPAHs) and nitrated PAHs (NPAHs) remain unclear. Some of them are more toxic and can be transformed from PAHs in environment. This study explored and compared the concentrations composition profiles and potential sources of PAHs, OPAHs, and NPAHs in soil and vegetation samples from the three polar regions. The total PAH, OPAH, and NPAH concentrations were 3.55-519, n.d.-101, and n.d.-1.10 ng/g dry weight (dw), respectively. The compounds were dominated by three-ring PAHs, and the most abundant individual PAH and OPAH were phenanthrene (PHE) and 9-fluorenone (9-FO), respectively. The sources of PAHs and their derivatives were qualitatively analyzed by the diagnostic ratios and quantified using the positive matrix factorization (PMF) model. The ratios of PAH derivatives to parent PAHs (9-FO/fluorene and 9,10-anthraquinone/anthracene) were significantly higher in the Antarctic samples than in the Arctic and TP samples, implying a higher occurrence of secondary OPAH and NPAH formation in the Antarctic region. To our knowledge, this is the first comparative study that simultaneously investigated the contamination profiles of PAHs and their derivatives in the three polar regions. The findings of this study provide a scientific basis for the development of risk assessment and pollution control strategies in these fragile regions.

Integrating compound-specific stable isotope and enantiomer-specific analysis to characterize the isomeric and enantiomeric signatures of hexachlorocyclohexanes (HCHs) in paddy soils

Organic pollutants in paddy fields may undergo different processes from those in dryland due to the anaerobic environment. The integrated use of compound-specific stable isotope analysis (CSIA) and enantiomer-specific analysis is a promising technique for understanding the behavior and fate of organic pollutants in soils. In this study, soil samples were collected from paddy fields in three major rice cultivation regions of China, spanning a transect of 4000 km. The mean concentrations of ƩHCHs in paddy soils from the Taihu Plain were the highest (1.44 ng/g). The ratios of α-HCH/β-HCH (all below 11.8) and α-HCH/γ-HCH (92% below 4.64), as well as the enantiomeric fractions (EFs) of chiral α-HCH (mean of 0.81), reflected that the distribution of HCHs was affected by the use of both technical HCHs and lindane. The preferential depletion of (-)-α-HCH and pronounced carbon isotope fractionation of α-HCH (δ13C of -28.22 ± 0.92‰ -23.63 ± 1.89‰) demonstrated its effective transformation. Factors such as altitude, soil temperature, soil pH, soil conductivity and soil organic matter significantly influenced the fate and transformation of HCHs. The current study highlights the integrated application of CSIA and enantiomer-specific analysis to provide multiple lines of evidence for the transformation of HCHs in soils.

Heavy metal pollution in Mongolian-Manchurian grassland soil and effect of long-range dust transport by wind

Grasslands provide a range of valuable ecosystem services, but they are also particularly fragile ecosystems easily threatened by human activities, such as long-term open-pit mining and related industrial activities. In grassland area, dust containing heavy metal(loid)s generated by mines may further migrate to remote places, but few studies have focused on the long-range transport of contaminants as an important pollution source. In the present study, one of the largest and most intact grassland ecosystems, the Mongolian-Manchurian steppe, was selected to investigate its pollution status and track potential sources. A total of 150 soil samples were collected to explore reginal distribution of nine heavy metal(loid)s that has potential risk in grassland. We conducted a combined multi-variant analysis of positive matrix factorization (PMF) and machine learning, which foregrounded the source of long-range transport of contaminants and inspired the hypothesis of a novel stochastic model to describe contaminants distribution. Results showed four different sources accounting for 44.44% (parent material), 20.28% (atmospheric deposition), 20.39% (farming), and 14.89% (transportation) of the total concentration, respectively. Factor 2 indicated that coal surface mining lead to a significant enrichment of As and Se with their concentration far above the global average level, which was different from other reported grassland areas. Machine learning results further confirmed that atmospheric and topographic features were their contamination controlling factors. The model results proposed that As, Se and Cu released by surface mining will be transported over long distance under prevailing monsoon, until finally deposited in the windward slope of mountain due to terrain obstruction. The long-range transport by wind and deposition of contaminants may be a prevailing phenomenon in temperate grassland, making it a pollution source that cannot be ignored. Evidence from this study reveals the urgency of precautions for fragile grassland ecosystems around industrial areas and provides a basis for its management and risk control policies.

Analysis of the distribution characteristics of prostate cancer and its environmental factors in China

The high incidence and mortality and the increasing trend of prostate cancer has been one of the public health issues in many countries and regions. Meanwhile, the spatio-temporal heterogeneity of prostate cancer implies that lifestyle and ecological changes may be associated with prostate cancer, however, sufficient evidence is still lacking. This paper tried to reveal the spatial and temporal distribution characteristics of prostate cancer in China and explore the potential associations with related socioeconomic and natural condition factors. Data on prostate cancer incidence and mortality in 182 counties (districts) in mainland China from 2014-2016 were collected, and the distribution characteristics of prostate cancer were analyzed using spatiotemporal scan statistic. Spatial regression models and geodetector method were used to analyze the potential associations between meteorological conditions, socioeconomic development, and prostate cancer incidence and mortality. SaTScan, GeoDa, and GeoDetector were used for the above statistical analyses. The high-risk clusters for prostate cancer incidence and mortality were located in southeastern China, and the low-risk clusters were located in north-central China. Spatial regression models showed that the number of industrial enterprises/km² (incidence: β = 0.322, P < 0.001; mortality: β = 0.179, P < 0.001), GDP (incidence:β = 0.553, P < 0.001; mortality: β = 0.324, P < 0.001), number of beds in medical and health institutions/1000 persons (incidence: β = 0.111, P = 0.005; mortality: β = 0.068, P = 0.021), and urbanization rate (incidence: β = 0.156, P < 0.001; mortality: β = 0.100, P < 0.001) were positively associated with the incidence and mortality of prostate cancer. The urbanization rate (incidence: q = 0.185, P < 0.001; mortality: q = 0.182, P < 0.001) has the greatest explanatory power, and the interaction of all factors was bivariate enhanced or nonlinearly enhanced. The distribution of prostate cancer in China has obvious spatial heterogeneity. The incidence and mortality rate of prostate cancer are on the rise, and special plans should be formulated in each region according to local conditions.

An evaluation of the impact of traffic on the distribution of PAHs and oxygenated PAHs in the soils and moss of the southeast Tibetan Plateau

Contaminants in high-altitude mountains such as the Tibetan Plateau (TP) have attracted extensive attention due to their potential impact on fragile ecosystems. Rapid development of the economy and society has promoted pollution caused by local traffic emissions in the TP. Among the pollutants emitted by traffic, polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) are of particular concern due to their high toxicity. The TP provides an environment to explore the degree and range of contribution for traffic-induced PAHs and OPAHs. In this study, soils and moss were collected at different altitudes and distances from the G318 highway in the southeast TP. The total concentrations of PAHs (∑₁₆PAHs) and OPAHs (∑₆OPAHs) in soils were in the range of 3.29-119 ng/g dry weight (dw) and 0.54-9.65 ng/g dw, respectively. ∑₁₆PAH and ∑₆OPAH concentrations decreased logarithmically with increasing distance from traffic. A significantly positive correlation between ∑₁₆PAHs and altitude was found at sampling points closest to traffic. Dominant PAHs constituents in soil and moss included chrysene (CHR), benzo[g,h,i]perylene (BghiP), and benzo[b]fluoranthene (BbF); prevalent OPAH compounds were 9-fluorenone (9-FO) and 9,10-anthraquinone (ATQ). These compounds were related to characteristics of traffic emissions. The multiple diagnosis ratio and correlation analysis showed that exhaust emissions were the main source of the PAHs and OPAHs in the studied environment. PMF modeling quantification of the relative contribution of traffic emissions to PAHs in roadside soils was 45 % on average. The present study characterized the extent and range of traffic-induced PAH and OPAH emissions, providing valuable information for understanding the environmental behaviors and potential risks of traffic-related contaminants in high-altitude areas.

Development of structural equation models to unveil source-sink switches of mid-latitude soils for semi-volatile banned pesticides

A variety of semi-volatile banned pesticides (SVBPs) are ubiquitous in soils of mid-latitude regions. SVBPs undertake complicated soil-gas exchange processes in mid-latitude regions, challenging the understanding of source or sink roles of soils for the semi-volatile contaminants. Herein, we develop structural equation models (SEMs) to unveil source or sink roles of mid-latitude soils (Liaoning, China) in winter and summer for 12 SVBPs (7 organochlorine and 5 organophosphorus pesticides). The 12 SVBPs exhibit different distribution patterns in soils, dependent of sampling seasons, soil characteristics, topographic/climate conditions of soil sites and chemical properties of compounds. SEM Model I (winter) and Model II (summer) reveal the distribution patterns of SVBPs in soils over season changes, indicating sink-source switches of soils for SVBPS from winter to summer. In winter, soil is a sink of 12 SVBPs in the study area, associated with the inputs of SVBPs in soils by air-particulate partition and dry depositions. However, in summer, soil is mainly a source of the same contaminants, mainly through the volatilization and leaching of SVBPs in soils. The sink-source switches of soils for SVBPs are usually dependent of chemical properties of compounds to higher extents than soil characteristics and topographic/climate conditions of soil sites, though these parameters pose different influences in winter and summer. It has been revealed that soil acts as a sink of SVBPs in winter, associated with the inputs of SVBPs in soils by air-particulate partition and dry depositions, whereas soil acts as a source of SVBPs in summer, mainly through the volatilization and leaching of SVBPs in soils. This finding may provide new insights into the unique distribution patterns of SVBPs in soils in mid-latitude regions.

A Pilot Study on the Concentration, Distribution and Bioaccumulation of Polybrominated Diphenyl Ethers (PBDEs) in Tissues and Organs of Grassland Sheep

Polybrominated diphenyl ether (PBDE) concentrations in various tissues and organs of grassland sheep from Inner Mongolia, China, were determined. The abilities of PBDEs binding to ovine serum albumin (OSA) and Cytochrome P450 enzyme (CYP3A24) were assessed by fluorescence spectroscopy and molecular docking simulations. The PBDE concentrations in the sheep tissue and organ samples were 33.4-167 pg/g dw. The distribution of PBDEs in sheep organs and tissues is affected not only by the function of organs and tissues, but also by the characteristics of PBDEs. Adipose tissue tends to bioaccumulate more-brominated BDEs (BDE-154, -153, and -183), but muscle tissues and visceral organs mainly bioaccumulate less-brominated BDEs. The distribution of PBDEs in visceral organs is mainly affected by the transport of ovine serum albumin (OSA) and the metabolism of CYP3A24 enzyme. The distribution of PBDEs in adipose tissue and brain is mainly affected by their logK_OW.

Occurrence, Distribution and Health Risk of Short-Chain Chlorinated Paraffins (SCCPs) in China: A Critical Review

With being listed in the Stockholm Convention, the ban on short-chain chlorinated paraffins (SCCPs) has been put on the agenda in China. Based on the literature over the past decade, this study comprehensively analyzed the occurrence, distribution of and human exposure to SCCPs in China, aiming to provide a reference for the changes in SCCPs after the ban. SCCPs were ubiquitous in environmental matrices, and the levels were considerably higher than those in other countries. SCCPs from the emission region were 2–4 orders of magnitude higher than those in the background area. Environmental processes may play an important role in the SCCP profiles in the environment, and C10 and Cl6 were identified as potential factors distinguishing their spatial distribution. River input was the dominant source in the sea areas, and atmospheric transport was the main source in the remote inland areas. Ingestion and dermal absorption and food intake may pose potential risk to residents, especially for children and infants. More studies are needed on their temporal trend, source emission and environmental degradation. The enactment of the restriction order will have a great impact on China’s CP industry; nevertheless, it will play a positive role in the remediation of SCCP pollution in the environment.

Complex chemical cocktail, containing insecticides diazinon and permethrin, drives acute toxicity to crustaceans in mountain lakes

Mountain lakes have long been perceived as pristine environments. However, atmospheric deposition of persistent organic pollutants (POPs) have been shown to expose these sensitive ecosystems to chemical pollution. Little is known on how this pollution impacts aquatic ecosystems at high altitudes. We combined passive sampling with liquid and gas chromatography high resolution mass spectrometry (LC- and GC-HRMS) to screen the water of eight lakes in three different regions of the French Pyrenees. In total, we screened for 479 organic chemicals including POPs, polycyclic aromatic hydrocarbons (PAHs), legacy and current-use pesticides, biocides, and musk fragrances. We detected a complex cocktail of 151 individual chemicals and used their toxic unit summation (ΣTU) to assess toxicity for crustaceans and algae. While risks for algae never reached chronic risks, this was always the case for crustaceans. Acute toxic risk thresholds for crustaceans were even exceeded in several of our sites. At sites with acute toxic risk levels (> 0.1 ΣTU) crustaceans were completely absent or showed a low abundance. We conclude that crustaceans were at least partly impacted by the high toxic risks driven by the insecticides diazinon and permethrin. These drugs are widely used to protect livestock from blue tongue disease transmitted by sucking insects, suggesting free roaming livestock as local source. Our results provide important evidence on toxic chemical pollution in relatively remote mountain areas, with important consequences for aquatic mountain ecosystems.

Occurrence and distribution of polyhalogenated carbazoles in eastern Tibetan Plateau soils along the slope of Mt. Qionglai

Polyhalogenated carbazoles (PHCZs), are considered as potential persistent organic pollutants (POPs), which have been frequently detected in the environment. However, the altitudinal distribution characteristics and possible sources of PHCZs in high mountain soils are still unknown. The present study was the first to analyze PHCZs in soil samples collected along the eastern slope of Mt. Qionglai (MQ), the east edge of the Tibetan Plateau. The concentration of ΣPHCZs (based on dry weight) ranges from 14.4 to 107 ng/g (median value of 40.9), which was at high end of the range reported in soils and sediments to date in the literature. The composition profiles of PHCZs in the soils of MQ were dominated by 3,6-dichlorocarbazole (36-CCZ), 3-chlorocarbazole (3-CCZ), and 2-bromocarbazole (2-BCZ). The mean TOC-normalized concentrations of ΣPHCZs in soil samples from below-treeline (2092 ng/g TOC) were higher than those from alpine meadow (1124 ng/g TOC), probably due to the forest filter effect. The decreasing trend of the PHCZs TOC-normalized concentrations with altitude shows that accumulation of PHCZs from the alpine meadow samples was not affected by the mountain cold-trapping effect. Significantly positive correlations were observed between the concentrations of more than half of detected PHCZ congeners and TOC. In addition, PHCZs show the potential to represent a class of POPs with the frequent occurrence and wide distribution, as the abundance and environmental behavior of PHCZs are similar to some POPs in MQ.

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.

Three-dimensional spatial distribution of legacy and novel poly/perfluoroalkyl substances in the Tibetan Plateau soil: Implications for transport and sources

Driven by increasingly stringent regulations on the legacy poly/perfluoroalkyl (PFASs), a variety of fluorinated alternatives have emerged on the market. Tibetan Plateau (TP) plays an important role in accumulation of organic pollutants due to its high altitude and wet deposition. In this study, the occurrence, spatial distribution and sources of PFASs in the TP soils were investigated. The total concentrations of PFASs ranged from 0.814-4.51 ng/g in the TP soils, with the identification of a variety of novel PFASs, including fluorotelomer sulfonates (FTSs), chlorinated polyfluorinated ether sulfonic acid (Cl-PFESAs), and hexafluoropropylene oxide (HFPO) homologues. Generally, the PFAS concentrations exhibited an increase trend from the west to east, and gradually increased with the altitude increasing, suggesting the impacts of human activities and mountain cold-trapping. The PFASs decreased with the increase of soil depth, but at different extents, which were related to their occurrence time, interactions with organic matters, and microbial transformation in soil. Most of the PFASs were present as free fractions in soil, particularly for the short-chain perfluoroalkyl acids (PFAAs), implying that they were liable to be accumulated in organisms and transport to groundwater. Multiple source apportionment analyses indicated that PFASs in the soil of TP were not only derived from the local pollution, but also from the atmospheric migration influenced by Indian Monsoon and westerly winds.

The potential risks and exposure of Qinling giant pandas to polycyclic aromatic hydrocarbon (PAH) pollution

Rapid industrialization and urbanization have created a substantial urban-rural gradient for various pollutants. The Qinling Mountains are highly important in terms of biodiversity, providing habitat for giant pandas, which are endemic to China and are a widely recognized symbol for conservation. Whether polycyclic aromatic hydrocarbon (PAH) exposure risks regarding in situ animal conservation zones are affected by environmental pollution or even enhanced by the mountain-trapping effect requires further research. Our group carried out a large-scale investigation on the area ranging from Xi'an to Hanzhong across the giant panda habitat in the Qinling Mountains by collecting atmosphere, soil, bamboo, and fecal samples from different sites over a two-year period. The total toxicity of atmospheric PAHs and the frequencies of soil PAHs above effect range low (ERL) values showed a decreasing trend from urban areas to the central mountains, suggesting a distance effect from the city. The proportions of total 5- and 6-ring PAHs in the atmosphere were higher in the central mountainous areas than in the urban areas, while this difference was reversed in the soil. Health risk assessments showed that the incremental lifetime carcinogenic risks (ILCR) of PAH exposure by bamboo ingestion ranged from 2.16 × 10^-4 to 3.11 × 10^-4, above the critical level of 10^-4. Bamboo ingestion was the main driver of the PAH exposure risks. The concentration difference between bamboo and fecal samples provided a reference for the level of PAHs absorbed by the panda digestive system. Since the Qinling Mountains possess the highest density of giant pandas and provide habitats to many other endangered animal and plant species, we should not ignore the probability of health risks posed by PAHs. Monitoring the pollution level and reducing the atmospheric emissions of toxic pollutants are recommended actions. Further detailed research should also be implemented on pandas' health effects of contaminant exposure.

Novel brominated flame retardants (NBFRs) in soil and moss in Mt. Shergyla, southeast Tibetan Plateau: Occurrence, distribution and influencing factors

Research on the environmental fate and behavior of novel brominated flame retardants (NBFRs) remains limited, especially in the remote alpine regions. In this study, the concentrations and distributions of NBFRs were investigated in soils and mosses collected from two slopes of Shergyla in the southeast of the Tibetan Plateau (TP), to unravel the environmental behaviors of NBFRs in this background area. The total NBFR concentrations (∑₇NBFRs) ranged from 34.2 to 879 pg/g dw in soil and from 72.8 to 2505 pg/g dw in moss. ∑₇NBFRs in soil samples collected in 2019 were significantly higher than those in 2012 (p < 0.05). Decabromodiphenyl ethane (DBDPE) was the predominant NBFR, accounting for 90% of ∑₇NBFRs on average. The ratio of the concentrations in moss and soil showed significantly positive correlations with LogK_OA except for DBDPE (p < 0.05), indicating that the role of mosses as accumulators compared to soils are more pronounced for more volatile NBFRs. In addition, the concentrations of NBFRs generally decreased with increasing altitude on the south-facing slope, whereas on the north-facing slope some NBFRs exhibited different trends, suggesting concurrent local and long-range transport sources. Normalization based on total organic carbon/lipid concentrations strengthened the correlation with altitude, implying that the altitude gradient of the mountain slope and forest cover could jointly affect the distribution of NBFRs in the TP. Furthermore, principal components analysis (PCA) with multiple linear regression analysis (MLRA) showed that the average contribution of the mountain cold trapping effect (MCTE) accounted for the major (77%) contribution and forest filter effect (FFE) has only a modest contribution to the deposition of NBFRs in soil.

Occurrence, sources and potential risks of polycyclic aromatic hydrocarbons in a permafrost soil core, northeast China

Polycyclic aromatic hydrocarbons (PAHs) in an AMS ¹⁴C-dated permafrost soil core extracted from continuous permafrost zone were measured to reconstruct the pollution history from the early Holocene (ca. 15480 a BP) and its potential risks under climate changes were evaluated in northeast China. Total PAH concentrations varied from 209 to 2161 ng/g through the core, which were moderately contaminated in the surface but heavily contaminated historically. Factor analysis indicated that volcanic activity, diagenesis from biological precursors and palaeo forest fires were dominant PAH sources, while petroleum emission was identified in the active layer due to the construction of China-Russia oil pipeline. Significant increases in 5-ring, 6-ring and 7 carcinogenic PAHs (p < 0.05) were observed from surface to the interface of the active layer and ice-rich permafrost layer, showing a selective downward migration in the active layer which might be effected by the repetitive cycles of freezing and thawing. Results implied that PAHs in the ice-rich permafrost layer could lead to an unpredictably serious consequence under the further climate warming.

Accumulation of PBDEs and MeO-PBDEs in notothenioid fish from the South Shetland Islands, Antarctica: An interspecies comparative study

Concentrations of polybrominated diphenyl ethers (PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs); are reported in specimens of fish notothenioids Chaenocephalus aceratus (SSI), Trematomus bernacchii (ERN), and Nototheniops nudifrons (NOD) from the South Shetland Islands, Antarctica. Significant differences in the accumulation of 2'-MeO-BDE-68 and 6-MeO-BDE-47 were detected among the analysed species. MeO-BDEs were significantly higher in SSI (11.7, 8.6, and 14.1 ng g^-1 lw) than in NOD (1.63, 1.63, and 3.0 ng g^-1 lw) in muscle, liver, and gill, respectively. Feeding ecology traits explain the accumulation patterns of MeO-PBDEs. SSI has a higher feeding activity with a broader diet, followed by ERN, whereas NOD is a benthic/sedentary fish with a narrower diet. The accumulation of PBDEs was neither species-, nor tissue-specific. The current study expands the knowledge concerning the accumulation of PBDEs and MeO-PBDEs in Antarctic marine fish and supports the importance of species-specificity in the accumulation of MeO-PBDEs.

Polycyclic aromatic hydrocarbons in sedimentary cores of Tibetan Plateau: Influence of global warming on cold trapping

Cold condensation is an important pathway for polycyclic aromatic hydrocarbons (PAHs) depositing at remote alpine lakes after long-range atmospheric transportation. However, in the context of global warming, the obvious temperature rise in the Tibetan Plateau (TP) might have an impact on the air deposition of PAHs by controlling the extent of cold condensation. To investigate the influence of rising temperatures on the atmospheric deposition of PAHs, two dated sedimentary cores from Pumoyum Co Lake (PC) and Selin Co Lake (SC) were collected, respectively and concentrations of 16 individual PAHs were measured. In both PC and SC, the total concentration of 16 PAHs presented relatively lower levels in four historical periods of "hot anomaly" including 1973-1975, 1988-1989, 1998-1999, and 2006-2007. This indicated that the hot temperatures might restrict the atmospheric deposition of PAHs. Besides, the results of the principal component analysis did discriminate those "hot anomalies". As the temperature kept increasing in TP, for low molecular weight PAHs and high molecular weight PAHs, the influence of rising temperatures on the cold condensation was different. Therefore, it was identified that the effect of global warming on the environmental fate of POPs cannot be neglected, especially in alpine regions like TP.

Contrasting compositions and sources of organic aerosol markers in summertime PM2.5 from urban and mountainous regions in the North China Plain

Although the chemical compositions and sources of organic aerosols (OAs) have been extensively investigated at the summit of Mt. Tai in the North China Plain (NCP), their vertical distributions and characterizations in the Mt. Tai region is not well known. To better understand the vertical variations of OAs in the urban and mountainous atmosphere, PM_2.5 samples were collected simultaneously on a daytime/nighttime basis at two sites of different altitudes (Taian urban site: 20 m above ground; the summit of Mt. Tai: 1534 m a.s.l.) during the summer of 2016. The concentrations of all the determined chemical compounds (e.g., OC, EC, inorganic ions, saccharides, n-alkanes, PAHs and hopanes) except for biogenic secondary organic aerosol (BSOA) tracers decreased with the increase in sampling height, indicating the relatively larger contribution of anthropogenic pollutants to OAs at the lower heights. The relatively low concentration levels of biomass burning tracers (e.g., levoglucosan, galactosan and mannosan) and the insignificant correlations of levoglucosan with carbonaceous species demonstrated a negligible effect of biomass burning on the mountaintop atmosphere. The enhanced concentrations of BSOA tracers were observed with the increase of height, largely due to the more intensive secondary oxidation of volatile organic compounds (VOCs) under the stronger radiation conditions at the summit. The daytime concentrations of carbonaceous species, primary sugars, sugar alcohols, PAHs and low molecular weight n-alkanes were significantly higher than those in nighttime at Mt. Tai, suggesting that these chemical compounds at the summit of Mt.Tai aerosols were transported from the ground surface by valley breezes in daytime. There was no correlation between BSOA tracers and relative humidity (RH) or liquid water content (LWC) at both the sites, because both the high RH and LWC can suppress the acid-catalyzed formation of BSOA due to the dilution of the aerosol acidity.

Long-range atmospheric transport and alpine condensation of short-chain chlorinated paraffins on the southeastern Tibetan Plateau

Pristine alpine regions are ideal regions for investigating the long-range atmospheric transport and cold trapping effects of short chain chlorinated paraffins (SCCPs). The concentrations and alpine condensation of SCCPs were investigated in lichen samples collected from the southeastern Tibetan Plateau. The concentrations of SCCPs ranged from 3098 to 6999 ng/g lipid weight (lw) and appeared to have an increasing trend with altitude. For congeners, C₁₀ dominated among all the congener groups. The different environmental behavior for different congener groups was closely related to their octanol-air partition coefficient (K_oa). C₁₀ congeners showed an increasing trend with altitude, whereas C₁₃ congeners were negatively correlated with altitude. Volumetric bioconcentration factors (BCF) of SCCPs reached 8.71 in lichens, which were higher than other semivolatile organic compounds (SVOCs) such as organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and hexabromocyclododecane (HBCD). These results suggested that SCCPs were prone to accumulate in the lichen from the air and provided evidence for the role of lichens as a suitable atmospheric indicator in the Tibetan Plateau.

Distribution of the Soil PAHs and Health Risk Influenced by Coal Usage Processes in Taiyuan City, Northern China

The quality of urban soil is closely related to the safety of public places and the guarantee of food quality. This study investigated the level, distribution, source, and carcinogenic risk of 16 U.S. EPA (Environmental Protection Agency) priority polycyclic aromatic hydrocarbons (PAHs) in urban, agricultural, and montane soil in Taiyuan. The ∑16PAHs level varied from 104.78 to 6594.63 ng g^-1 with a mean of 922.93 ng g^-1, and 47.73% of the soil samples were severely contaminated, with a concentration higher than 600 ng g^-1. PAHs with higher molecular weight (≥4 rings) were dominant in PAHs profiles accounting for 80.92%. In the spatial distribution of PAHs, hotspots of ∑16 PAHs were observed near the industries, indicating pollutants emitted by the industries directly affect the surrounding soil quality. The sources identified by positive matrix factorization (PMF) indicated: coal combustion (40.77%), vehicle exhausts (32.94%), biomass combustion (14.89%), and coking source (11.40%). Coal-related sources (coal and coking sources) were the major contributors (52.17%) to PAHs and carcinogenic risk (46.48%) assessed by BaP toxic equivalent concentration in total soils. Therefore, the extensive usage of coal was the leading factor for PAH pollution and health risk in Taiyuan soil.

Short- and medium-chain chlorinated paraffins in multi-environmental matrices in the Tibetan Plateau environment of China: A regional scale study

Research on the environmental fate and behavior of short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively), especially in high-altitude remote mountain areas, has rarely been conducted. In this study, the distribution and profiles of SCCPs and MCCPs in soils, barks, needles, lichens, and mosses in the Tibetan Plateau area were investigated during the period from 2010 to 2016. The total CP concentrations in soils, barks, needles, lichens, and mosses increased with increasing altitude from 1983 to 5147 m a.s.l. (above sea level), covering a range of 1843.5 km × 370.6 km. Generally, the mean SCCP levels were higher than mean MCCP levels in different environmental matrices. Moreover, as-obtained linear relationships between CP concentrations in different environmental matrices and altitudes (p < 0.05) indicated that the mountain cold-trapping could affect the presence and congener patterns of both SCCPs and MCCPs in the Tibetan Plateau environment. C_10-11 and C₁₄ congener groups were found to be the dominant groups in SCCPs and MCCPs in the environmental samples, respectively. Finally, the back-trajectory model was employed to reveal the differences of the potential sources in different regions of the Tibetan Plateau.

Sources and spatio-temporal distribution of aerosol polycyclic aromatic hydrocarbons throughout the Tibetan Plateau

With the recent rapid development of urbanization, atmospheric pollutants such as polycyclic aromatic hydrocarbons (PAHs) have attracted wide attention, particularly in remote regions. The Tibetan Plateau (TP), known as the third pole is adjacent to areas with heavy atmospheric pollution, such as South and East Asia. However, the spatial distribution and sources of PAHs on the TP remain unclear. Thus, we investigated the sources and spatio-temporal distributions of PAHs on the TP by combining aerosol sample data from six sites, including Ngari (NG), Laohugou (LHG), Beiluhe (BLH), Nam Co (NMC), Everest (EV), and Yulong (YL), in 2014 and 2016. The average concentrations of 15 PAHs at the six sites ranged from 3.4 to 15.2 ng m^-3, with a decreasing trend from the marginal to inner areas of the plateau. The highest concentration was that in YL in the southeastern part of the TP, with an average of 15.2 ng m^-3. The PAH concentrations in NG, NMC, and YL were higher in autumn and winter and lower in summer. High molecular weight PAHs usually exists in the particulate phase whereas tricyclic PAHs can change from particulate to gaseous phase, therefore it can indicate long-range transport. Tricyclic PAHs were the dominant PAHs on the TP (44%-58%), indicating long-range atmospheric transport as the major source of PAHs. Principal component analysis (PCA) and diagnostic ratio analysis showed that biomass and coal combustion were the major sources of PAHs in inland areas of the TP; however, marginal plateau areas were affected by fossil fuel emissions. Compared with levels in Beijing and other urban sites, the toxic equivalent quantity (TEQ) was low (0.36-1.06 ng m^-3), suggesting a low risk to human and ecosystem health.

Age dependence accumulation of organochlorine pesticides and PAHs in needles with different forest types, southeast Tibetan Plateau

In this study, organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs) in needle leaves with different ages were measured in three prevalent coniferous forests including spruce, fir and pinus in southeast Tibetan Plateau (TP) to investigate accumulation behavior of persistent organic pollutants (POPs) during entire growth cycle of needles. The accumulation concentration of POPs was higher in pinus and fir needles than in spruce needles. Concentrations for most of OCPs significantly increased with needle ages, especially dichlorodiphenyltrichloroethane (DDT) and its metabolites showed more remarkable increasing trend than hexachlorocyclohexane isomers (HCHs) and hexachlorobenzene (HCB) in the three tree species. However, age dependence accumulation of PAHs was not observed in most cases, possibly due to its easier degradation property and the influence by dramatic change of ambient atmospheric concentration of PAHs. The lipid normalized concentrations in needles exhibited similar accumulation pattern with that of dry weight basis. The controlling factors for concentration variation in needles were identified using multiple linear regression. The suitability of these needle species acting as potential passive sampler for atmospheric POPs was evaluated. The different-age needles could reflect atmospheric OCP concentrations in the past long-term trend. Findings of this study provide guidance in use of needle as passive samples for the background monitoring of the atmospheric contamination at remote and poorly accessible locations such as the TP.

New classes of organic pollutants in the remote continental environment - Chlorinated and brominated polycyclic aromatic hydrocarbons on the Tibetan Plateau

Halogenated polycyclic aromatic hydrocarbons are carcinogenic and ubiquitous environmental organic pollutants. The abundance and sources of these compounds have not been studied in remote environments. We collected and analyzed air, soil, lichen, and moss samples from the Tibetan Plateau. Concentrations of chlorinated polycyclic aromatic hydrocarbons were 0.78-4.16 pg/m³ in air, 3.11-297 pg/g in soil, 260-741 pg/g in lichens, and 338-934 pg/g in mosses. Concentrations of brominated polycyclic aromatic hydrocarbons were 0.15-0.59 pg/m³ in air, 0.61-72.3 pg/g in soil, 33.5-64.9 pg/g in lichens, and 20.5-72.5 pg/g in mosses. The dominant congeners were 9- and 2-chlorophenanthrene, 1-chloropyrene, 3-chlorofluoranthene, and 1-bromopyrene. We found correlations between congener concentrations in lichens and in air, and lichens effectively predicted near-ground atmospheric concentrations of the pollutants. The enrichment of photochemically stable compounds in high-altitude environments is influenced by their physicochemical properties. Principal component analysis with multivariate linear regression of chlorinated polycyclic aromatic hydrocarbons measured in lichens provided an assessment of the relative source contributions, and suggested that in Medog County of Tibetan Plateau, 48% was likely from long-range combustion sources, 26% was from local burning sources, and 26% was from photochemical formation.

Polychlorinated Naphthalene Congener Profiles in Common Vegetation on the Tibetan Plateau as Biomonitors of Their Sources and Transportation

Polychlorinated naphthalenes (PCNs) are globally transported, carcinogenic, persistent organic pollutants (POPs) that were recently added to the Stockholm Convention with 184 parties. The Tibetan Plateau plays an important role in the global transportation and distribution of POPs. Knowledge of PCN sources and transportation on the Tibetan Plateau is important for their control globally. In this study, we quantified the congener-specific concentrations of PCNs in lichen, moss, soil, and air samples collected on the Tibetan plateau and found that common lichens were effective biomonitors for predicting atmospheric PCNs in this area. The physiochemical properties of the PCNs, the temperatures, and the lichen lipid contents were identified as important factors influencing PCN partitioning between lichens and air. Lichen-air partitioning equations were established and used to predict PCN concentrations in air in Southeast Tibet. The lichens could be used as PCN biomonitors to clarify their spatial variations, sources, and transportation in the southeast of the plateau. PCN concentrations in lichens increased with altitude, suggesting that high-mountain cold-trapping influenced the PCN transportation behavior. Principal component analysis and linear discriminant analysis showed that the major source of PCNs in this region was long-range atmospheric transportation via the Indian monsoon in summer and wind from Southwest Asia in winter. This study provides a novel method using PCN congener profiles as fingerprints and statistical models for studying the geochemical effects of conditions in high-mountain regions on the contamination behaviors of 75 congeners of the notorious PCNs.

Assessment of Cu, Zn, Mn, and Fe enrichment in Mt. Kenya soils: evidence for atmospheric deposition and contamination

Mountains are the preferred sites for studying long-range atmospheric transportation and deposition of heavy metals, due to their isolation and steep temperature decrease that favors cold trapping and condensation of particulate forms of heavy metals. Any enrichment of heavy metals in mountains is presumed to primarily occur through atmospheric deposition. In this particular study, we assessed the status of 27 subsurface soils collected along two elevation gradients of Mt. Kenya using enrichment factors (EFs) as the ecological risk assessments. The collected soils were analyzed for total organic carbon, zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu). The mean concentration of Mn, Fe, Zn, and Cu was 0.376 mg/kg, 47.6 mg/kg, 12.3 mg/kg, and 4.88 mg/kg in Chogoria and 0.560 mg/kg, 113 mg/kg, 12.7 mg/kg, and 2.70 mg/kg in Naro Moru respectively. These concentrations were below the US-EPA maximum permissible levels for soils, implying that the levels recorded had low toxicity. Meanwhile, the mean enrichment factors for Mn, Cu, and Zn were 0.447, 131, and 78.8 in Chogoria and 0.463, 38.9, and 53.0 in Naro Moru respectively. This implied that Zn and Cu in Chogoria sites were extremely enriched, while in Naro Moru, enrichment levels ranged from significant to extreme. However, Mn was found to have minimal enrichment in all the sites. Lower montane forest and bamboo zone recorded relatively high enrichment due to distance from source of pollution. Ericaceous zone also had high mean enrichment due to influence of wind which favors higher deposition at mid-elevations.

Characterization of atmospheric and soil polycyclic aromatic hydrocarbons and evaluation of air-soil relationship in the Southwest of Buenos Aires province (Argentina)

Sixteen polycyclic aromatic hydrocarbons (PAHs) proposed by the US EPA as priority were analyzed in air and soil samples in the Southwest of Buenos Aires, Argentina, in order to study the levels, distribution, sources and fugacity ratios of PAHs, evaluating the relationship between them. For this, 10 passive air samplers (XAD-2® resin) were deployed along the area and replaced three-monthly from January to December 2015. PAHs were analyzed through gas chromatography -mass spectrometry (GC-MS). Results obtained showed that total PAHs levels (∑16) ranged from 27.97 to 1052.99 ng m^-3 and from 52.40 to 2118.34 ng. g^-1 d.w. for air and soil samples, respectively. The highest air- PAHs levels were registered in Bahía Blanca city (1052.99 ng. m^-3, d.w.) an urban-industrial site, while the highest soil-PAHs levels were found in La Vitícola (2118.34 ng. g^-1, d.w.), a rural location closed to a high traffic national route. For all sites the highest levels were observed during the winter; however, both spatial and temporal variations were only statistically significant for certain specific PAHs. Diagnostic ratios + PCA, determined dominance of pyrolytic sources. Further, data showed that source of PAHs could be attributed to vehicular and industrial emissions (observed in all periods), biomass combustion (linked mainly to warm period) and domestic emissions (linked mainly to cold period). Finally, fugacity ratios resulted <1, indicating that soil and air samples were not in equilibrium for the majority of PAHs determining a net tendency of air PAHs towards deposition while soil acted principally as a sink.

Occurrence of organochlorine compounds in fish from freshwater environments of the central Andes, Argentina

The Central Andes region is considered an area of high environmental relevance in South America and it is rich in glaciers, which are the main fresh water sources and reservoirs of the region. The presence of organochlorine compounds (OCs) is an environmental threat due to their persistence and adverse effects on wildlife and humans. The levels of OCs, such as chlordane compounds (CHLs), dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs), were determined in muscle and liver tissues of fish and in sediments collected from different sites of the central Andes: the Mendoza River and the Yaucha River (rainbow trout: Oncorhynchus mykiss) and Carrizal Dam (silverside: Odontesthes bonariensis). Regardless of studied site and fish tissue, the general OC trend was: DDTs > PCBs > HCHs > CHLs > HCB. The results showed clear geographic distribution patterns for DDTs. Among the sampling sites, silverside fish showed the highest average load of DDTs (614 and 867 ng g^-1 lw in muscle and liver tissues, respectively). Based on the biota-sediment bioaccumulation factor (BSAF), both rainbow trout and silverside fish showed comparable capability to accumulate p,p'-DDT in their tissues. Intraspecific correlational analysis showed that CB-138 in muscle and p,p'-DDT in liver were clearly correlated with the lipid content in silverside specimens, which highlights the relevance of taking into account the fat content and the type of target tissues.

Forage system is the key driver of mountain milk specificity

The aims of this work were to determine the effect of upland origin on milk composition when comparing similar lowland and upland production system and to highlight the factors responsible for the added value of upland milk from commercial farms. Tanker milk from 55 groups of farms (264 farms in total) in France, Slovakia, and Slovenia was collected twice during the indoor season and 3 times during the outdoor season. The tanker rounds were selected in each country to be balanced according to their origin (lowland or upland) and within upland or lowland groups, according to the forage systems: corn-based or grass-based forage system. At each milk sampling, the production conditions were recorded through on-farm surveys. The milk was analyzed for gross composition, carotenoids, minerals, fatty acids, phenolic compound derivatives, volatile organic compound concentrations, and color. The milk from upland and lowland areas differed in their contents of a few constituents. Upland milk was richer in not identified (n.i.) retention time (Rt) 13,59, 4-methylpentylbenzene, 1-methyl-2-n-hexylbenzene, and β-caryophyllene than lowland milk. These differences could be most likely attributable to the utilization of highly diversified and extensively managed semi-natural grasslands. The higher forbs content of upland pastures could be related as well to the richness in C18:3n-3, CLA cis-9,trans-11, MUFA, and PUFA we observed in upland compared with lowland milk during the outdoor season. In contrast, grazing on lowland pastures rich in grasses gave a yellower milk that was richer in β-carotene. Out of the few compounds showing a significant effect of origin or its interaction, most of the milk constituents were unaffected by the origin at all. However, almost all milk constituents differed according to the forage system and the season, and the differences observed between seasons can be attributed to differences in the cow diet composition.

Accumulation and fate processes of organochlorine pesticides (OCPs) in soil profiles in Mt. Shergyla, Tibetan Plateau: A comparison on different forest types

Previous work documented that forest plays an important role in the deposition of persistent organic pollutants (POPs) in the southeast Tibetan Plateau (TP) due to the "forest filter effect". However, forest types in the southeast TP are entirely different and the influence on POPs fate and forest filter effect by different forests remains unclear. This study focused on the distribution and transfer of organochlorine pesticides (OCPs) in soil of different forest types (quercus, birch, fir, and spruce dominated forests) in Mt. Shergyla, southeast TP under similar environmental and meteorological conditions. Total levels of ∑HCHs, ∑DDTs and HCB in soils ranged from < LOD to 2.25 ng/g dry weight (dw), < LOD-10.2 ng/g dw, and < LOD-0.95 ng/g dw, respectively. Concentrations of OCPs in humus layers were significantly higher than those in mineral layers in the four forest types. Relatively higher ∑DDTs concentrations were found in soil profile of broadleaved birch forest, while higher concentrations of ∑HCHs and HCB were found in soil profile of coniferous fir forest, and the same trend was observed in fresh leaf samples. Air-to-ground fluxes and mobility of OCPs in the four forest types were also evaluated. Relatively higher fluxes were found in fir forests than in other forest types, suggesting that fir forest could be more effective to transfer OCPs from the air into soil in the southeast TP. The findings in this study would be helpful for improving model simulation of POPs fate in different forest ecosystem.

Bulk atmospheric deposition of persistent organic pollutants and polycyclic aromatic hydrocarbons in Central Europe

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are ubiquitous and toxic contaminants. Their atmospheric deposition fluxes on the regional scale were quantified based on simultaneous sampling during 1 to 5 years at 1 to 6 background/rural sites in the Czech Republic and Austria. The samples were extracted and analysed by means of gas chromatography coupled to mass spectrometry. For all seasons and sites, total deposition fluxes for Σ15PAHs ranged 23-1100 ng m-2 d-1, while those for Σ6PCBs and Σ12OCPs ranged 64-4400 and 410-7800 pg m-2 d-1, respectively. Fluoranthene and pyrene were the main contributors to the PAH deposition fluxes, accounting on average for 19% each, while deposition fluxes of PCBs and OCPs were dominated by PCB153 (26%) and γ-hexachlorobenzene (30%), respectively. The highest deposition flux of Σ15PAHs was generally found in spring, while no seasonality was found for PCB deposition. For deposition fluxes for Σ12OCPs, no clear spatial trend was found, confirming the perception of long-lived regional pollutants. Although most OCPs and PCBs hardly partition to the particulate phase in ambient air, on average, 42% of their deposition fluxes were found on filters, confirming the perception that particle deposition is more efficient than dry gaseous deposition. Due to methodological constraints, fluxes derived from bulk deposition samplers should be understood as lower estimates, in particular with regard to those substances which in ambient aerosols mostly partition to the particulate phase.

Altitude-dependent accumulation of short chain chlorinated paraffins in fish from alpine lakes and Lhasa river on the Tibetan Plateau

High mountain cold-trapping effects can play important roles in the global long-range transport of persistent organic pollutants (POPs). Short chain chlorinated paraffins (SCCPs) have recently been included into the Stockholm Convention as a new class of POPs. However, the long-range transport behavior and environmental fate of SCCPs still remain largely unknown in high-altitude mountain areas. In this study, a total of 51 fish samples were collected from five high-altitude mountain lakes and Lasha river across the Tibetan Plateau. SCCPs were positively detected in all fish samples, and the concentrations ranged from 3.9 to 107 ng g^-1 dry weight (dw) with an average of 26.6 ng g^-1 dw. Compared to aquatic organisms from the Artic and Antarctica, the SCCP levels found in alpine fish from the Tibetan Plateau were lower. A significant increasing trend in accumulation levels of SCCPs in alpine fish with the increasing altitude was found on the Tibetan Plateau (r = 0.98, p < 0.001). Shorter chain congener group C10 showed a significant increase in percentage contribution to total SCCPs with increasing altitude, but a contrary tendency was found for longer chain congener group C13. The widespread occurrence of SCCPs in Tibetan fish was mainly sourced from the long-range atmospheric transport, and the altitude-dependent distribution of SCCPs was due to the mountain cold-trapping effects and potential susceptibility to bioaccumulation. To our knowledge, this is the first report regarding the altitude-dependent accumulation of SCCPs in biota in the polar environment.

Trans-Himalayan Transport of Organochlorine Compounds: Three-Year Observations and Model-Based Flux Estimation

High mountains can trap semivolatile chemicals, such as persistent organic pollutants (POPs), and hinder their dispersion. However, both deep convection and mountain valleys can facilitate POPs' transport over mountains, which have not been investigated before. In this study, a three-year sampling campaign along a south-north altitudinal transect (100-5200m) across the central Himalayas, coupled with a multicompartment contaminant fate model, was conducted for describing the transport processes of POPs. The results show that POPs emitted in the lowlands of the Himalayas can be transported to high altitudes and further to the inner part of the Tibetan Plateau. Modeling suggests that more than 90% of POPs are trapped along the way due to gaseous deposition to soil/foliage and rainfall scavenging; while 2 × 10^-3 to 1 × 10^-1 Giga-grams/year of POPs are transported across the Himalayas. The transport flux along valleys is 2-3 times higher than that across the mountain ridge. However, due to the limited spatial coverage of mountain valleys, the amount of POPs transported through valleys only accounts for a small part of the total transport. This study shows that POPs can overcome the blocking effect of the Himalayas, and high altitude transport across the mountain ridge is the dominant transport pathway.

The sedimentary record of polycyclic aromatic hydrocarbons in Yamzho Yumco Lake: evolution of local sources and adsorption dynamic in the Tibetan Plateau

With the rapid increase in anthropogenic activities, the local emissions of polycyclic aromatic hydrocarbons (PAHs) in background regions, such as the Tibetan Plateau (TP), have attracted great attention. The deposition of PAHs in lake sediments provides a historical evolutionary record of such compounds in these regions. To investigate the evolution of PAHs in the TP, two sedimentary cores from Yamzho Yumco Lake were collected and dated at high resolution, and the concentrations of 16 PAHs and sediment properties were also analyzed. The total concentrations of the 16 PAHs ranged from 6.52 to 57.97 ng/g (dry weight) in YC1 and from 0.91 to 4.57 ng/g (dry weight) in YC2. According to the methods of principal component analysis (PCA) followed by multilinear regression analysis (MLRA), four sources of PAHs in the sediments were qualitatively and quantitatively identified, such as petroleum combustion, petrogenic, coal combustion, and biomass burning. Thus, the historical evolution of PAHs was summarized. In addition, the transported distance from local PAH emission sources was found to greatly affect the composition and concentration of PAHs in sites YC1 and YC2. Specifically, local sources contributed a greater proportion of heavy molecular weight (HMW) PAHs in YC1 and a higher proportion of light-molecular-weight (LMW) PAHs in YC2. Moreover, fine particles (size < 20 μm) were found to play a significant role in adsorbing PAHs in sediments. Furthermore, ∑₁₆PAHs in sediments were linearly correlated with the percentage of fine particles (size < 20 μm). This study provides a first example to investigate the historical evolution of PAH local emission in background regions by using lake sedimentary records, especially in the TP. Specifically, different local sources were identified using the methods of PCA followed by MLRA, and PAHs in TP sediments were predominantly adsorbed by fine particles rather than by total organic carbon (TOC) because the amount of TOC was limited.

Characteristics of polycyclic aromatic hydrocarbons (PAHs) in soil horizon from high-altitude mountains in Northeastern China

Previous studies have reported that soils from high altitude mountains act as primary reservoirs of polycyclic aromatic hydrocarbons (PAHs). This study aims to investigate the spatial distribution and illuminate the behaviors of PAHs in soil profiles from Mt. Wangtiane in Northeastern China. Soil samples were collected by different soil genetic horizon rather than by depths at 10 sites, with altitudes from 1000 m to 2022 m. Results showed significantly (p < 0.05) higher concentrations of total PAHs (16 PAHs) in O-horizons (371 ± 32 to 2224 ± 207 ng g^-1) than those in A- and B-horizons (362 ± 30 to 666 ± 58 ng^-1 and 289 ± 23 to 571 ± 50 ng g^-1, respectively). An increasing trend of PAH concentrations with altitude was observed from elevation ca. 1000 m to ca. 1800 m, but no correlation between PAH concentrations and altitude along transect was found. Total organic carbon (TOC) was strongly correlated (p < 0.05) with PAH concentrations in O-horizons but showed no relation with those in A- and B-horizons. Low molecular weight (LMW) PAHs were dominated in each soil horizon, and decreased percentage of high molecular weight (HMW) PAHs with depths in soils profiles was observed. Principle component analysis (PCA) separated O-horizons and A-/B-horizons based on PAH compositions, again suggesting different PAH compositions among soil horizons. These results reflect various processes of PAHs, including deposition, vertical motion, degradation and photolysis. This study suggests it is better to investigate characteristics of PAHs in soils by horizon rather than by depths.

Persistent organic pollutants in the polar regions and the Tibetan Plateau: A review of current knowledge and future prospects

Due to their low temperatures, the Arctic, Antarctic and Tibetan Plateau are known as the three polar regions of the Earth. As the most remote regions of the globe, the occurrence of persistent organic pollutants (POPs) in these polar regions arouses global concern. In this paper, we review the literatures on POPs involving these three polar regions. Overall, concentrations of POPs in the environment (air, water, soil and biota) have been extensively reported, with higher levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) detected on the Tibetan Plateau. The spatial distribution of POPs in air, water and soil in the three polar regions broadly reflects their distances away from source regions. Based on long-term data, decreasing trends have been observed for most "legacy POPs". Observations of transport processes of POPs among multiple media have also been carried out, including air-water gas exchange, air-soil gas exchange, emissions from melting glaciers, bioaccumulations along food chains, and exposure risks. The impact of climate change on these processes possibly enhances the re-emission processes of POPs out of water, soil and glaciers, and reduces the bioaccumulation of POPs in food chains. Global POPs transport model have shown the Arctic receives a relatively small fraction of POPs, but that climate change will likely increase the total mass of all compounds in this polar region. Considering the impact of climate change on POPs is still unclear, long-term monitoring data and global/regional models are required, especially in the Antarctic and on the Tibetan Plateau, and the fate of POPs in all three polar regions needs to be comprehensively studied and compared to yield a better understanding of the mechanisms involved in the global cycling of POPs.

Two-way long-range atmospheric transport of organochlorine pesticides (OCPs) between the Yellow River source and the Sichuan Basin, Western China

This study revealed a two-way long-range atmospheric transport of organochlorine pesticides (OCPs) rather than a single mode, in Western China. Soil and air samples were collected along a transect with length of ca. 1000 km between the Yellow River source in the Qinghai-Tibet Plateau and the Sichuan Basin. Concentrations of ΣOCPs in soils and air were detected to be 175-69,229 (median 567) pg/g dry weight and 33.6-271 (median 98.3) pg/m³, respectively. HCB, HCHs, DDTs, and SULPHs (sum of Endosulfan-I, Endosulfan-II and Endosulfan sulfate) were dominant. Isomeric ratios suggested dominant weathered technical HCH, technical DDT and chlordane profile, and confirmed the current-use of Endosulfan along the transect. Furthermore, local fresh input of Lindane and possible illegal use of technical DDT might occur in the basin area. Based on isomeric and metabolic ratios, fractionation and principal component analysis, a two-way transport system was determined. One flowed from the Sichuan Basin to the Qinghai-Tibet Plateau comprising HCB, HCHs, and DDTs, while the other flowed reversely from the Qinghai-Tibet Plateau to the Sichuan Basin dominating by SULPHs and CHLs (including Heptachlor, Heptachlor epoxide, trans-chlordane, and cis-chlordane). Multiple linear regression analysis demonstrated greater average contributions of the Sichuan Basin sources onto the soil ΣOCPs than that of the Qinghai-Tibet Plateau source. Distinct from the single long-range atmospheric transport, our results highlighted the different source-sink roles of the Qinghai-Tibet Plateau and the Sichuan Basin for different OCP compounds.

Congener-specific C10C13 and C14C17 chlorinated paraffins in Chinese agricultural soils: Spatio-vertical distribution, homologue pattern and environmental behavior

A comprehensive spatio-vertical survey of short-chain (SCCPs, C_10-13) and medium-chain (MCCPs, C_14-17) chlorinated paraffins (CPs) was performed in surface and core soils from Chinese nation-wide agricultural lands in 2016, and a total of 48 congener groups were measured. The shorter carbon chain C_10-11 in SCCP and C_14-15 in MCCP homologue groups, and the lower chlorinated congeners (Cl_5-7) for both CP groups were predominant. The ∑SCCP and ∑MCCP concentrations in surface soils ranged from 39 to 1609 ng/g and 127-1969 ng/g, dry weight (dw), respectively. The spatial distribution trend showed that SCCP congener groups with relatively low octanol-water partition coefficient (K_OW) and octanol-air partition coefficient (K_OA) are uniformly distributed across surface soils compared to MCCP congener groups. Significant relationships were observed between the spatial variation of SCCP concentrations and the driving factors responsible for dispersion and deposition. The distribution behavior of SCCPs and MCCPs in highland and plain surface soils showed an increasing trend of MCCP concentrations with elevation, indicating the "mountain cold-trapping effect". Vertical distribution profile revealed similar homologue group composition patterns of SCCP and MCCP congener groups as those of surface soils. Furthermore, the penetration potential ratios (r) of chlorine and carbon atoms of CPs demonstrated that the lower chlorinated (Cl_5-7) and the shorter carbon chain (C_10-13) congener groups are more prone to vertical movement into deeper soil layers compared to the longer carbon chain (C_14-17) and highly chlorinated (Cl_8-10) congener groups.

The atmospheric transport and pattern of Medium chain chlorinated paraffins at Shergyla Mountain on the Tibetan Plateau of China

Large amounts of short chain and medium chain chlorinated paraffins (SCCPs and MCCPs) are released into the environment during production and usage. However, compared to SCCPs, there is a significant lack of attention for MCCPs. In this work, 83 air samples, collected between 2012 and 2015 from the Tibetan Plateau, were analyzed to investigate the airborne levels and distributions of MCCPs, further to evaluate their potential long-range transport behavior on the alpine area. The total air MCCP concentrations at Shergyla Mountain and Lhasa were between 50 and 690 pg/m³ and 800-6700 pg/m³, respectively. At Shergyla Mountain, MCCP concentrations in the air appeared an increasing trend with altitude, which indicated that MCCPs could potentially possess the ability of "mountain cold trapping". C₁₄ and C₁₅ congener groups were the dominant homologue groups. The mountain contamination potential (MCP) of different congener groups is closely related to their equilibrium partitioning coefficients between octanol and air (K_OA), and water and air (K_WA). Increasing MCCPs levels might be a potential threat to the environment and human exposure.

Distribution and vertical migration of polycyclic aromatic hydrocarbons in forest soil pits of southeastern Tibet

PAHs could be transported to Tibetan Plateau in accompany with atmospheric circulation. The forest regions were found be an important sink for PAHs, while their distributions and migrations in forest are still uncertain. In this study, soil profile samples were collected in southeastern Tibet and the concentrations, distributions, and migration of PAHs in forest region were investigated. The PAHs levels in the forest soils were at the low end of remote sites, ranged from 27.4 to 120.3 ng g^-1 on a dry weight based. Due to low ambient temperature and high organic carbon content, enrichment of PAHs was found in higher altitude on north side. According to the soil profiles, the vertical distributions of PAHs in organic layers were mainly influenced by pedogenesis, while the vertical distributions in mineral layers were dominated by downward leaching effect. Enrich factor (EF) of PAHs was estimated, and the values in organic layers were positively correlated with the octanol-air partition coefficients (K _OA), but EFs in mineral layers decreased with the K _OA values. PAHs in the surface soils on the north side of forest were relatively stable, while the migration of PAHs on the south sides and other clearing sites was more active. The leaching rates of PAHs in clearing site ranged between 1.42 and 29.3%. The results from this study are valuable on the characterization of PAHs in Tibetan Plateau.

Polychlorinated Biphenyls in Surface Soil from North-East India: Implication for Sources Apportionment and Health-Risk Assessment

Although India never manufactured polychlorinated biphenyls (PCBs), evidence suggests the prevalence of PCBs in multi-environmental matrices. Despite the high level of PCBs that has been detailed in the major urban areas of India, little is known about the fate and sources of PCBs in Northeast India (NEI). This motivated us to investigate the contamination level and sources of PCBs in the surface soil. In this study, the environmental concentration and sources of 25 PCBs were investigated in surface soil (n = 60) from three states of NEI (lower Assam, Manipur, and Tripura). Additionally, the relationship between soil organic carbon (SOC) and PCBs was studied to investigate the role of SOC in the distribution of PCBs. Overall, the concentration of ∑₂₅PCBs ranged from 2950 to 16,700 pg/g dw (median 7080 pg/g dw), 3580-21,100 pg/g dw (median 11,500 pg/g dw), and 2040-11,000 pg/g dw (median 4270 pg/g dw) in Assam, Manipur, and Tripura, respectively. Low-chlorinated PCBs were more prevalent than highly chlorinated PCBs. PCB-49 was identified as the most abundant in soil, followed by PCB-52, and accounted for 13% and 12.9% of ∑₂₅PCBs, respectively. With respect to land use categories, high ∑₂₅PCBs were related to grassland areas and proximity to the roadside soil. The principal component analysis indicated emissions from technical PCB mixtures, combustion of municipal wastes/residential wood, incineration of hospital wastes, and e-waste recycling/disposal sites are the real sources of PCBs. Marginally, a moderate-to-weak correlation of SOC with ∑₂₅PCBs (R² = 0.144, p < 0.05) and their homologs (R² = 0.280-0.365, p < 0.05) indicated the little role of SOC in the dispersion of PCBs. The estimated toxic equivalency of dioxin-like PCBs suggested that PCB-126 is the most toxic contaminant to endanger the human population.

Altitudinal dependence of PCBs and PBDEs in soil along the two sides of Mt. Sygera, southeastern Tibetan Plateau

Surface soil samples were collected from Mt. Sygera in the southeast of Tibetan Plateau to investigate the altitudinal distribution of PCBs and PBDEs along the two sides of the mountain. The average concentrations of PCBs and PBDEs were 177 pg g-1 dw and 15 pg g-1 dw, respectively. The relationships between the log-transformed TOC-normalized concentrations and the altitudes showed different trends on the two sides. On the windward side, there was a positive correlation for the heavier PCBs; while on the leeward side, the concentrations increased and then decreased for PCBs and PBDEs at the altitude of 4100-4200 m, corresponding to the change in vegetation. The observed discrepancy on the two sides of the mountain demonstrated different key factors associated with precipitation and the forest canopy. Additionally, values of windward-leeward Enrichment Factors (W/L EFs) for the heavier PCB congeners (PCB-138, 153, and -180) were an order of magnitude higher in sites above 4200 m, which also suggested that vegetation played an important role in the altitudinal accumulation of POPs in soil. This is one of the very few studies that have revealed the differences in altitudinal accumulation of POPs along the two sides of a mountain.

Air-Seawater Gas Exchange and Dry Deposition of Chlorinated Paraffins in a Typical Inner Sea (Liaodong Bay), North China

As a group of new persistent organic pollutants, short-chain chlorinated paraffins (SCCPs) and medium-chain CP (MCCPs) have attracted extensive worldwide interest in recent years. However, the data regarding to the environmental behavior, especially in atmospheric transfer and air-seawater exchange, are still sparse. In this study, seasonal marine boundary layer air and seawater samples were collected from Chinese Bohai sea and a fugacity model was built to evaluate the air-seawater diffusion and deposition flux of CPs. Generally, the total CP levels in atmosphere and seawater samples in summer were higher than those in spring, and CPs existed mostly in the gaseous phase in air and the dissolved phase in seawater. For SCCPs, C₁₀ and C₁₁ components were the most abundant homologue groups. For MCCPs, the C₁₄ homologue dominated in the particle phase of atmosphere and particulate phase of seawater. The logarithmic fugacity ratios (log f_a/ f_w) of higher chlorinated congeners (Cl₈ to Cl₁₀: 0.71 to 1.32 in May and 1.38 to 2.29 in August) indicated that net deposition was the predominant process, whereas lower chlorinated congeners, especially Cl₅ homologue groups in August, showed a trend of net volitization (log  f_a/ f_w < -0.5). The results of diffusion and dry deposition fluxes indicated that air-seawater gas exchange of CPs was significantly higher than dry deposition in the sampling areas.