No anthropogenic pollutant is more widespread in the aquatic and terrestrial environment than microplastic; however, there are large knowledge gaps regarding its origin, fate, or temporal variations in the oceans. In this study, we analyzed sediment trap material from the deep subtropical Northeast Atlantic (2000 m) in a long-term record (2003–2015) to assess the role of the deep ocean as a potential sink of microplastics. Microplastic particles were identified in all 110 analyzed samples with flux rates of 1.13–3146.81 items d⁻¹ m⁻². Calculated microplastic mass fluxes ranged between 0.10 and 1977.96 μg d⁻¹ m⁻², representing up to 8% of the particle flux. Between years, the composition of the different polymers changed significantly, dominated by polyethylene, whose amount was correlated with the lithogenic input. The correlation between polyethylene and the lithogenic fraction was attributed to an air transport pathway from northeast Africa and surrounding regions. The second most abundant polymer detected in our study was polyvinyl chloride, which is not correlated with lithogenic or biogenic particle flux fractions. Instead, we observed seasonality for polyvinyl chloride with recurring high fluxes in winter before the plankton bloom and significantly lower amounts in summer. Other polymers identified were polypropylene, polyethylene terephthalate, and lower numbers of polystyrene and polymethyl methacrylate. The average microplastic particle size for all samples and polymers was 88.44 ± 113.46 μm, with polyethylene and polyvinyl chloride having the highest proportion of small particles (<100 μm). Our findings provide first insights into temporal variations of sinking microplastics, which are crucial for understanding the fate of plastic in the oceans.

The present study shows the occurrence of 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209) in microbial biofilms of Pyrenean and Tatra high mountain lakes despite its low vapor pressure and high hydrophobicity. Aerosol air transport is therefore a feasible mechanism for BDE-209 accumulation in sites up to 2688 m above sea level. This compound and other PBDEs exhibit altitudinally-dependent distribution involving higher concentrations with increasing mountain lake elevation. However, the apparently very high enthalpies of the concentration gradients observed, including BDE-209, suggest that bacterial anaerobic debromination also plays a significant role in the resulting altitudinal distributions. This microbial mechanism explains the relative abundances of PBDEs and their within lake differences between rocky and sediment microbial biofilms, thereby showing that the altitudinal pattern observed is not purely due to water temperature control on bacterial activity but also to changes in the availability of anaerobic microenvironments which increase with increasing lake productivity at lower altitudes.

Plastic materials are increasingly produced worldwide with a total estimated production of >8300 million tonnes to date, of which 60% was discarded. In the environment, plastics fragment into smaller particles, e.g. microplastics (size < 5 mm), and further weathering leads to the formation of functionally different contaminants – nanoplastics (size <1 μm). Nanoplastics are believed to have entirely different physical (e.g. transport), chemical (e.g. functional groups at the surface) and biological (passing the cell membrane, toxicity) properties compared to the micro- and macroplastics, yet, their measurement in the environmental samples is seldom available. Here, we present measurements of nanoplastics mass concentration and calculated the deposition at the pristine high-altitude Alpine Sonnblick observatory (3106 MASL), during the 1.5 month campaigh in late winter 2017. The average nanoplastics concentration was 46.5 ng/mL of melted surface snow. The main polymer types of nanoplastics observed for this site were polypropylene (PP) and polyethylene terephthalate (PET). We measured significantly higher concentrations in the dry sampling periods for PET (p < 0.002) but not for PP, which indicates that dry deposition may be the preferential pathway for PET leading to a gradual accumulation on the snow surfaces during dry periods. Air transport modelling indicates regional and long-range transport of nanoplastics, originating preferentially from European urban areas. The mean deposition rate was 42 (+32/-25) kg km⁻² year⁻¹. Thus more than 2 × 10¹¹ nanoplastics particles are deposited per square meter of surface snow each week of the observed period, even at this remote location, which raises significant toxicological concerns.

Surface soils were collected in Balang Mountain to explore the environmental process of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) during air transport. The average concentrations of ∑₂₅PCBs and ∑₁₃PBDEs in soils were 163 pg/g and 26 pg/g, respectively. The significant correlations between the concentrations of pollutants and total organic carbon (TOC) indicated the importance of TOC in accumulation potential of POPs. The slopes from fitted curves of PCBs were highly related with logKₒₐ, demonstrating that TOC dominates the soil-air exchange of PCBs. The TOC-normalized concentrations of contaminants in samples from below-treeline were higher than those from alpine meadow, probably due to the forest filter effect. The increasing trends of the concentrations with altitude from the alpine meadow samples, could be attributed to the mountain cold-trapping effect. And the weak cold-trapping effect of POPs might be due to the less precipitation in 2008 when comparing with those in 2006.

Polycyclic Aromatic Hydrocarbons (PAHs) are among the main persistent organic pollutants in the Arcticwhich enter the polar region from lower latitudes by air transport and ocean currents and accumulate in marine sediments. This work represents the first study in 25 years of the least studied and hard-to-reach areas of Siberian arctic seas. Sixteen priority PAHs as well as 1- and 2-methylnaphthalenes were analyzed by gas chromatography – tandem mass spectrometry in the twenty-four sediment samples taken from Kara, Laptev and East Siberian Seas in October 2020. The obtained sum concentrations ranged from 31 to 223 ng/ g with the greatest contribution of phenanthrene, benzo[b]fluoranthene, benzo[k]fluoranthene, as well as naphthalene and its methyl derivatives while the greatest PAH levels were observed in Laptev Sea. No correlations between sum PAH concentration, total organic carbon and black carbon contents were found. The toxic equivalent in benzo[a]pyrene units was from 2.2–18.2 ng/ g that shows the general safe environmental situation in the region. The overall PAH level is comparable with the data obtained in 1990s which indicates a long-term persistence of pollution despite an overall decline in global PAH emissions. The main sources of PAHs involve mainly coal/biomass and liquid fuel combustion with weaker contribution of petroleum sources.

Over the years, the world has been plagued by issues brought about by environmental degradation, climate change, and environmental health issues. Core to the environmental risk and security issues is the greenhouse gas emission which reflects carbon dioxide emissions effect on global climate. In order to better understand this stuff, the study explored the combined effect of increasing railway transport, air transport and urbanisation on the environment in emerging economies from 1995 to 2016. The study employed the Pesaran CD, average mean group (AMG), correlated effect mean group (CCEMG) and cointegration test approach. The study revealed that rail transport and urban population show good statistical strength to improve the environment. Findings from the study indicate that the proliferation of the emerging economies such as India, China, Brazil, Mexico, Indonesia, Turkey and Russia has greatly contributed to the growth of environmental sustainability. There is a lot of policy blueprint mentioned in this study, in which when adhere to could provide pertinent decision advocate in building quality environmental economies.

Recently, greenhouse gas (GHG) emissions become the hottest issue in the transportation sector. The air transport sector contributes approximately 2% of global greenhouse gas emissions. Reducing greenhouse gas emissions from aircraft is one of the issues taken seriously by the transportation sector. However, air transportation has implemented several ways to reduce carbon emissions, and one of them is by launching a carbon offset program. This study estimates the willingness among Malaysian airline passengers to pay for a carbon offset program to have a better environmental performance. Using a double-bounded dichotomous choice of contingent valuation method (CVM) estimates how much air passengers would be willing to pay to offset carbon emissions generated by their travel. The results obtained from this study suggest that the additional fee for airline tickets will be RM86.00 can be charged to have a better environmental performance.

To optimize the accessibility algorithm and quantify the potential relationship between human development index and traffic comprehensive accessibility system, this paper analyzed the spatial distribution pattern of urban accessibility and human development index of highway, railway, and aviation transportation systems using data on highway, railway, and aviation schedules based on GIS spatial analysis method. Furthermore, the coupling degree between human development index and accessibility and its influence mechanism on the city level in China were explored based on the super-efficiency data envelopment analysis model. Results showed as follows: (1) Spatial distribution of human development index from high to low was gradually changing from east to west. The spatial distribution of urban accessibility of the three traffic systems had an evident “Hu Huanyong Line” effect. (2) The coordination degree of urban accessibility and human development index spread in a ladder mode. High coordination of cities in North and East China and the central Yangtze River region forms the spatial distribution of urban development circles connecting an urban development belt. (3) Railway connectivity and control value were highly sensitive to human development index in cities where serious imbalance between accessibility and human development index. Highway connectivity and control value were highly sensitive to human development index in cities where high coordination between accessibility and human development index. The results would provide scientific references for spatial planning of transportation, economic, and social development of cities and coordinated development of urban agglomeration in China.

In environmental management, many studies have examined the energy consumption-emission nexus in detail. However, for the first time in the literature, this study considers how the Economic Complexity Index (ECI) and economic policy uncertainty (EPU) moderate the contribution of energy consumption to emissions for the four World Bank Income clusters. The system generalised methods of moments are applied to data for 109 countries from 1996 to 2016. Based on the main model (grouped clusters) estimations, the result revealed the existence of the environmental Kuznets curve (EKC) hypothesis. Also, an increase in air transport and consumption of energy releases more carbon emissions to the climate. Interestingly, ECI decreases carbon emission significantly while EPU does not have a significant impact. Moreover, the study revealed that ECI moderated the impact of other variables on emission, but EPU is not a significant moderator. Furthermore, a comparative analysis among the four incomes suggests that the EKC hypothesis holds only in the high-income clusters; ECI is a significant predictor of carbon emission in the four clusters, but it only decreases the emission in high-income clusters. This corroborates the debate on climate change and the productive capacity of high-income countries. Given the foregoing, several policy measures were recommended.

Global travel and tourism have enjoyed a significant boost due to the progress in air transport. However, the debate on air transport and the influx of foreign investments and global energy demand on economic development remains questionable. Therefore, this study is an attempt to contribute to the body of knowledge in the energy-tourism-led growth hypothesis literature. For this purpose, a novel approach to the effects of international tourism on economic growth is introduced for the Next-5 largest economies, namely (China, India, Indonesia, Turkey and the USA) between 1990 and 2018. Empirical results reveal a positive connection between foreign direct investment and income levels, electricity production and income levels, as well as between urbanization and economic growth. Moreover, the validation of the environmental Kuznets curve and the halo effect of foreign direct investment on the environmental degradation process provides a shred of more substantial evidence and fitting environmental instruments for policymakers. The empirical results encourage sustainable economic growth in these countries, mainly through the attraction of clean and high-technology foreign investment, the increase of the share of renewable energy sources in the energy mix and the regulation in the tourism industry. The novel contribution of this study to the empirical literature is the unification in the same research of the TLGH and the EKC for the Next-5 largest economies, establishing recommendations for tourism, energy efficiency and environmental correction process.