Pristine Regions Research Articles

Quantification of the Total and Extractable Content of Micro- and Trace Elements in Linden Blossom and Infusions—The Impact of Urban Pollution on Health Risk for Samples from Plovdiv, Bulgaria

Linden (Tilia) is one of the most frequently utilized plants for the preparation of infusions because of its salutary effects, including the reduction in inflammatory processes and pain, alleviation of stress, and lowering of blood pressure. As Linden is a common species in Bulgarian cities, it is frequently used for homemade infusions. The regular consumption of these tea beverages may contribute to the attainment of the recommended daily allowances of certain minerals, but it may also result in the accumulation of toxic elements within the human body. The present study compares the concentrations of essential and toxic elements in linden blossom collected from disparate locations in Plovdiv, Bulgaria, with those of samples gathered in ecologically pristine regions and commercially available products labeled “bio”. Both total element content and extractable forms in infusions were quantified by ICP-MS. The health risk due to consuming infusions was assessed by comparing the water, tea, drinks, and EFSA regulations. The applied cluster analysis divided the samples from the urban area into three groups related to traffic pollution. In spite of the short blooming period, the concentrations of Al, Fe, Pb, V, Cr, Co, Ni, and Cd in the samples from the most polluted areas are increased by a factor of two compared to those from the clean zones.

Evaluating the role of recalcitrant dissolved organic matter in bacterial community dynamics in urbanized freshwater ecosystems

Dissolved organic matter (DOM) and recalcitrant dissolved organic matter (RDOM) play distinct roles in shaping microbial communities. However, characterizing these roles is difficult, especially in ecosystems subjected to varying degrees of anthropogenic influence. This study investigated the molecular compositions and ecological impacts of DOM and RDOM in the Fen River, Shanxi Taiyuan, comparing pristine upstream regions with highly urbanized downstream areas. Using 16S rRNA gene sequencing and LC-MS-based metabolomics, we observed significant shifts in microbial community composition, diversity, and metabolic functions. Upstream communities, characterized by higher diversity, were dominated by Bacteroidota, Proteobacteria, and Cyanobacteria, while downstream communities, influenced by pollution, exhibited increased expression of genes related to amino acid metabolism. Fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed that upstream DOM contained higher proportions of complex, high molecular weight compounds, including significant proportions of carboxyl-rich alicyclic molecules (CRAM) and island of stability (IOS) compounds, which play key roles in long-term carbon storage and microbial carbon sequestration. In contrast, downstream DOM was characterized as having lower aromaticity and more saturated compounds, with reduced proportions of CRAM and IOS, reflecting the impact of anthropogenic activities. These findings underscored the critical roles of CRAM and IOS in regulating DOM stability and microbial communities, further highlighting the need for targeted pollution control strategies to preserve ecosystem function in urbanized water bodies.

Dual-decoding branch contrastive augmentation for image manipulation localization

With the rapid development of image editing techniques, forensic analysis to detect malicious image manipulation has become an important research topic. The current image manipulation detection and localization methods can accommodate diverse forms of tampering. However, their approach to handling various tampering detection types is limited to a uniform regression pathway. This approach fails to recognize the unique characteristics of copy-move tampering, which is significantly different from other tampering types. Employing a generic detection methodology indiscriminately poses the risk of confusing the training regression trajectory of the deep learning models. To mitigate this challenge, this paper introduces a novel framework featuring a dual-decoding branch structure specifically designed to augment features pertinent to copy-move tampering types. Moreover, it facilitates the detection of tampered regions, irrespective of the tampering type, within the main branch. To achieve this goal, we first introduce a contrastive augmentation module in the encoder, which maximizes the feature space distance between the manipulation regions and pristine regions. Next, we design a parallel attention module to extract more diverse multiscale features. Moreover, we introduce a constrained shifted-window dual attention module to extract tampering noise features. In the decoder, we design a dual-decoding branch to capture both the homologous and tampering features, and we employ contrastive learning to minimize the feature space distance of the homologous regions for copy-move manipulation detection. Finally, we design a category normalization loss function to balance the model’s attention across each category. Extensive experiments demonstrate that the proposed approach achieves state-of-the-art performance on various benchmark datasets.

Ultrafast water diffusion along the interface between oxidized and pristine regions in graphene oxide: Reactive molecular dynamics study

Graphene oxide (GO) is a promising membrane material due to its high water permeability. However, the exact physical mechanisms governing this process at the molecular level remain poorly understood, despite more than a decade of practical applications. In this article, we use classical molecular dynamics with the reactive potential ReaxFF to study the mobility of water molecules intercalated in GO and analyze the influence of its structure on diffusion processes. We highlight the previously unmentioned role of the interfacial area between oxidized and pristine graphene regions, which, according to our calculations, may be responsible for the ultrafast water transport observed in GO. This diffusion exhibits characteristics of a ballistic regime, suggesting another possible mechanism underlying GO’s high water permeability.

The impact of natural capital loss on blue-tourism economy: The Red Sea case study

Global tourism growth is threatening environmental health of several destinations. While negative impacts of tourism on environmental quality are being increasingly documented, the effects of degrading environmental quality on tourists’ choices have been largely neglected. Here we investigated the case study of Egyptian Red Sea, one of the world's most popular targets for blue tourism. We provide evidence that, in the North (Sharm El Sheikh), coral reefs experienced a progressive degradation (25–40 % from 1991 to 2023 in the most impacted touristic targets). We report multiple evidence that the loss of natural capital decreased the attractiveness of touristic areas: the shift of tourism flows towards the more pristine regions of the South (Marsa Alam) was unable to counterbalance the loss of Sharm El Sheikh. The significant decline in tourism flows (-23 %, 2009–2019) caused an estimated annual loss of ca. 1.77 billion USD (0.6 % of the Egyptian GDP in 2019). We conclude that, given the increasing demand of pristine environments as tourism target, an unsustainable ecosystem management can threaten local economies, particularly where nature integrity represents a key asset for destination choice. Policy makers should thus consider the convenience of protecting natural capital and/or carrying on ecosystem restoration interventions to recover their attractiveness and develop a sustainable blue-tourism economy.

Global Gridded Emission Inventory of Organophosphate Flame Retardants from 2010 to 2020.

As a substitute for brominated flame retardants, organophosphate flame retardants (OPFRs) have become a global concern due to their high toxicity and bioaccumulation. To paint an overall picture of OPFRs in the global environment, the present study develops a gridded global emission inventory of OPFRs on a spatial resolution of 1 × 1° from 2010 to 2020. Revealing a 3.31% average annual increase in emissions, totaling 21,324.42 tons. The production process is the primary source, accounting for 55.43% of emissions, with consumption processes making up the rest. Major sources are in Asia, North America, and Europe. The inventory is verified by implementing emission data into a global atmospheric transport model to predict OPFR concentrations in the global environment and comparing modeled concentrations with field sampled data. The results indicate that the inventory is reliable except for the pristine polar region, where the emission inventory and modeled concentrations underestimate OPFR levels in the atmosphere, likely resulting from ignorance of chemical reactions and the secondary derivative of parent OPFRs during their global long-distance atmospheric transport in the model. This comprehensive data set aids in formulating OPFR emission control policies and assessing health risks.

Relative multi-beneficial effect of MOs on plant health of chickpea (Cicer arietinum L. var. PG-186).

The phosphate solubilizing properties of Lysinibacillus macroides ST-30, Pseudomonas pelleroniana N-26, and Bacillus cereus ST-6 were tested for the chickpea crop of the Tarai region of Uttarakhand. These microbially inoculated plants have shown significant (p > 0.05) improvement in the plant health and crop health parameters, viz., root length, shoot length, fresh weight, dry weight, nodule number, nodule fresh weight, nodule dry weight, chlorophyll content, and nitrate reductase. The highest shoot length (46.10 cm) and chlorophyll content (0.57 mg g-1 fresh weight) were observed in ST-30 at 75 DAS with 20 kg P2O5/ha. Similarly, for plant P content, an increase of 90.12% over control was recorded in the same treatment. Treatments consisting of Lysinibacillus macroides ST-30 along with 20 kg/ha P2O5 were found to be most suitable as phosphatic fertilizer. Conclusively, sustainable agriculture practices in the Tarai as well as the field region may be developed based on a strategy of exploring microbial inoculants from the pristine region of the Western Himalayas. The presence and abundance of bacterial inoculants were confirmed through qRT-PCT. We conclude that the effective plant growth-promoting bacterium Lysinibacillus macroides ST-30 broadens the spectrum of phosphate solubilizers available for field applications and might be used together with 20 Kg/ha P2O5.

20th century climate warming and human disturbance triggered high aquatic production and strong water-column mixing in maar Lake Xiaolongwan, northeastern China

Lake ecosystems in northeastern (NE) China are sensitive to global environmental change, and are currently under threats of eutrophication and hypolimnetic anoxia. However, the lack of long-term records of lake production and anoxia in this region makes it difficult to discriminate the impacts of recent anthropogenic activity on lake ecosystems from natural ecosystem variability. This study investigates varved sediments from remote maar Lake Xiaolongwan, NE China and reconstructs high-resolution changes in lake primary production, anoxia, nutrient cycling and catchment processes over the past 1500 years using hyperspectral imaging inferred sedimentary total chlorophyll-a and bacteriopheophytin-a (Bphe-a), combined with sedimentary iron and phosphorus fractions data. Results show that, prior to discernible human impacts in this area from ∼600 CE to 1900 CE, lake primary production was higher during warm periods and reduced during cold periods. Bphe-a records show that hypolimnetic anoxia persisted regardless of temperature variability. Cluster analysis suggests that lake algal communities and biogeochemical conditions in the twentieth-century warm period are unprecedented and significantly different from any other time over the past 1500 years. This phenomenon mostly results from global warming and stronger local catchment disturbance in the early 1900s, combined with atmospheric pollution after the 1950s. Human-driven climate warming has caused stronger seasonal mixing (due to shortened ice-cover duration) and overall better oxygenation in the lake. This study demonstrates clear anthropogenic impacts to lake ecosytems in a relatively pristine region in NE China. We anticipate that our findings will have implications for understanding the status of aquatic ecosystems in NE China under future interacting stressors of anthropogenic climate warming and pollution.

Microscale is key to model current and future Maritime Antarctic vegetation

Despite being one of the most pristine regions in the world, Antarctica is currently also one of the most vulnerable to climate change. Antarctic vegetation comprises mostly lichens and bryophytes, complemented in some milder regions of Maritime Antarctica by two vascular plant species. Shifts in the spatial patterns of these three main vegetation groups have already been observed in response to climate change, highlighting the urgent need for the development of comprehensive large-scale ecological models of the effects of climate change.Besides climate, Antarctic terrestrial vegetation is also strongly influenced by non-climatic microscale conditions related to abiotic and biotic factors. Nevertheless, the quantification of their importance in determining vegetation patterns remains unclear. The objective of this work was to quantify the importance of abiotic and biotic microscale conditions in determining the spatial cover patterns of the major functional types, lichens, vascular plants and bryophytes, explicitly determining the likely confinement of each functional type to the microscale conditions, i.e., their ecological niche.Microscale explained >60 % of the spatial variation of lichens and bryophytes and 30 % of vascular plants, with the niche analysis suggesting that each of the three functional types may be likely confined to specific microscale conditions in the studied gradient. Models indicate that the main microscale ecological filters are abiotic but show the potential benefits of including biotic variables and point to the need for further clarification of vegetation biotic interactions' role in these ecosystems. Altogether, these results point to the need for the inclusion of microscale drivers in ecological models to track and forecast climate change effects, as they are crucial to explain present vegetation patterns in response to climate, and for the interpretation of ecological model results under a climate change perspective.

Quantum Simulations and Experimental Insights into Glyphosate Adsorption Using Graphene-Based Nanomaterials.

The increasing global demand for food and agrarian development brings to light a dual issue concerning the use of substances that are crucial for increasing productivity yet can be harmful to human health and the environment when misused. Herein, we combine insights from high-level quantum simulations and experimental findings to elucidate the fundamental physicochemical mechanisms behind developing graphene-based nanomaterials for the adsorption of emerging contaminants, with a specific focus on pesticide glyphosate (GLY). We conducted a comprehensive theoretical and experimental investigation of graphene-based supports as promising candidates for detecting, sensing, capturing, and removing GLY applications. By combining ab initio molecular dynamics and density functional theory calculations, we explored several chemical environments encountered by GLY during its interaction with graphene-based substrates, including pristine and punctual defect regions. Our results unveiled distinct interaction behaviors: physisorption in pristine and doped graphene regions, chemisorption leading to molecular dissociation in vacancy-type defect regions, and complex transformations involving the capture of N and O atoms from impurity-adsorbed graphene, resulting in the formation of new GLY-derived compounds. The theoretical findings were substantiated by FTIR and Raman spectroscopy, which proposed a mechanism explaining GLY adsorption in graphene-based nanomaterials. The comprehensive evaluation of adsorption energies and associated properties provides valuable insights into the intricate nature of these interactions, shedding light on potential applications and guiding future experimental investigations of graphene-based nanofilters for water decontamination.

Alder expansion stimulates nitrogen oxide (NOx) emissions from southern Eurasian permafrost peatlands

AbstractNitrogen oxides (NOx) play an important role for atmospheric chemistry and radiative forcing. However, NOx emissions from the vast northern circumpolar permafrost regions have not been studied in situ due to limitations of measurement techniques. Our goals were to validate the offline analytical technique, and based on this, to widely quantify in situ NOx emissions from peatlands in the southern Eurasian permafrost region. To this end, we conducted a comparison of online and offline flux measurements in 2018 and 2019 using the synthetic air flushing, steady‐state opaque chamber method. With differences in annual average and cumulative fluxes less than 0.1 μg N m−2 h−1 and 0.01 kg N ha−1 year−1, the online and offline fluxes were in good agreement, demonstrating the feasibility of conducting offline measurements in remote regions without power supply. The flux measurements over 2 years showed obvious NOx emissions of 0.05–0.14 and 0.13–0.30 kg N ha−1 year−1 in the hollow and hummock microtopography of permafrost peatlands, respectively. The rapid expansion of alder (Alnus sibirica) in the peatlands induced by permafrost degradation significantly increased soil mineral N contents and NOx emissions depending on the age of alder (0.64–1.74 and 1.44–2.20 kg N ha−1 year−1 from the alder forests with tree ages of 1–10 years and 11–20 years, respectively). Alder expansion also intensively altered the thermal state of permafrost including the sharp increases of soil temperatures during the non‐growing season from October to April and active layer thickness. This study provides the first in situ evidences of NOx emissions from the northern circumpolar permafrost regions and uncovers the well‐documented expansion of alders can substantially stimulate NOx emissions and thus, significantly affect air quality, radiative forcing, and ecosystem productivity in the pristine regions.

Semi-supervised image manipulation localization with residual enhancement

Images have become a significant medium for information transmission, while image forensics has garnered widespread attention from researchers. Due to the scarcity of finely annotated images in the field of image manipulation detection and localization, existing methods for locating manipulated images can only utilize a limited amount of data for model training. However, deep learning models typically require a large number of finely annotated images to fully leverage their powerful fitting capabilities. In this paper, we propose a semi-supervised image manipulation localization framework, employing semi-supervised learning to use unannotated images for deep learning model training. To achieve this goal, we first design a residual enhancement module that contains an encoding-decoding structure. The regression target of this branch is the pristine regions in the images to generate the reconstructed images. Next, we perform a residual operation between the reconstructed and original images to roughly locate the anomalous regions and refine the features extracted by the encoder. Secondly, we employ weakly-supervised learning by adding an image-level classification head to the final layer of the encoder. The classification head generates a class active map based on image-level classification results, which further guides the model’s feature augmentation. Finally, we formulate a specialized semi-supervised framework tailored for image manipulation detection, enabling the utilization of a large volume of unannotated data for model training. Extensive experimental results highlight the notable efficacy of the proposed approach, and outperforms state-of-the-art approaches.

Unveiling Microplastic Abundance and Distribution in an Oceanic Island: Offshore Depository or Local Pollution Indicator

Millions of tons of solid waste, mostly plastics, are annually dumped into the oceans, posing a major 21st-century environmental threat. Commercial shipping and ocean gyres exacerbate pollution on remote islands, resulting in the widespread presence of microplastics throughout the marine environment. Most of this pollution is plastics, and its fragmentation originates from microplastics (particles smaller than 5 mm). These debris are ubiquitous throughout the marine environment, dispersed among beaches, estuaries, on the water surface, and even on the seafloor. This study was carried out on São Miguel Island, Azores, where sediment samples were collected and analysed for microplastic (MP) abundance and dimension across eight areas covering the entire coastline of the island. Each area was divided into four sites along an inland–coastal gradient, from the stream to the ocean (upstream, downstream, coastal, and submerged marine sediments), following a nested design approach. In addition to this first method, 15 beaches, spread along the island’s shore, were also tested and compared. Fibres were the most common type of microplastic, with varying levels of abundance across different locations. Abundance generally increased closer to the coast, but there were occasional instances of high upstream concentrations due to heavy rains, which then accumulated near coastlines and beaches. This study revealed an important local MP source from an apparently pristine touristic region which, aligned with other recent findings, unveils an important and silent pollution issue potentially affecting oceanic islands that should be seriously addressed in future studies and raise concern for litter management and mitigation and environmental awareness actions.

Optical Properties and Possible Origins of Atmospheric Aerosols over LHAASO in the Eastern Margin of the Tibetan Plateau

The accuracy of cosmic ray observations by the Large High Altitude Air Shower Observatory Wide Field-of-View Cherenkov/Fluorescence Telescope Array (LHAASO-WFCTA) is influenced by variations in aerosols in the atmosphere. The solar photometer (CE318-T) is extensively utilized within the Aerosol Robotic Network as a highly precise and reliable instrument for aerosol measurements. With this CE318-T 23, 254 sets of valid data samples over 394 days from October 2020 to October 2022 at the LHAASO site were obtained. Data analysis revealed that the baseline Aerosol Optical Depth (AOD) and Ångström Exponent (AE) at 440–870 nm (AE440–870nm) of the aerosols were calculated to be 0.03 and 1.07, respectively, suggesting that the LHAASO site is among the most pristine regions on Earth. The seasonality of the mean AOD is in the order of spring > summer > autumn = winter. The monthly average maximum of AOD440nm occurred in April (0.11 ± 0.05) and the minimum was in December (0.03 ± 0.01). The monthly average of AE440–870nm exhibited slight variations. The seasonal characterization of aerosol types indicated that background aerosol predominated in autumn and winter, which is the optimal period for the absolute calibration of the WFCTA. Additionally, the diurnal daytime variations of AOD and AE across the four seasons are presented. Our analysis also indicates that the potential origins of aerosol over the LHAASO in four seasons were different and the atmospheric aerosols with higher AOD probably originate mainly from Northern Myanmar and Northeast India regions. These results are presented for the first time, providing a detailed analysis of aerosol seasonality and origins, which have not been thoroughly documented before in this region, also enriching the valuable materials on aerosol observation in the Hengduan Mountains and Tibetan Plateau.

Leveraging physics-based and explainable machine learning approaches to quantify the relative contributions of rain and air pollutants to wet deposition

A quantitative understanding of the roles of rainfall and pollutant concentrations in wet deposition is important because they critically influence terrestrial and aquatic ecosystems. However, their relative contributions to wet deposition, which vary across regions, have not yet been identified. We propose two methods that quantitatively separate the contributions of rain and pollutant concentrations to wet deposition: one is based on simplified equations describing the wet scavenging of pollutants and the other is based on random forest models employing SHapley Additive exPlanations. Three-dimensional long-term air quality simulations from 2003 to 2019 are used as inputs for both the physics-based and machine learning models. Remarkably, the results drawn from the explainable machine learning model are consistent with those from the physics-based approach: overall, rain is a more important limiting factor than pollutant concentrations and the relative contribution of rain is larger than that of pollutants by up to a factor of 3–4 in polluted regions. In polluted regions, pollutant concentrations can remain relatively high even in the presence of precipitation owing to continuous and intense emissions; therefore, wet deposition is limited by rainfall. The contribution of rainfall is larger by 1.5–2.5 than that of pollutant concentrations in regions even with low emissions and this considerably large role of rain suggests that regional or transboundary pollutant transport plays a key role in modulating wet deposition. However, in very remote regions, once the rainfall amount exceeds a certain value, rainfall no longer contributes to increasing wet deposition because atmospheric pollutants are readily removed by rain. So, the contributions of the two factors are comparable in pristine regions. Our results can serve as a basis for explaining interannual variations in wet deposition and for future projections of wet deposition under emission control plans and climate change scenarios across regions.

Assessment of atmospheric pollution by heavy metals using transplanted lichen Pseudevernia furfuracea (L.) Zopf in Niğde Province, Türkiye

Lichens have been demonstrated to be vulnerable to air pollution for more than 140 years, since pollutants have been shown to impact crucial metabolic processes in both algae and fungus. Lichens serve as bioindicators for air pollution levels in different places by collecting air pollutants in their thallus, including heavy metals, polycyclic aromatic hydrocarbons (PAHs), and sulfur dioxide (SO2). This study involved collecting samples of Pseudevernia furfuracea (L.) Zopf from a pristine forest region (Yapraklı-Çankırı) and transplanting them for two periods of three months each at six locations surrounding the polluted Niğde provincial center in Turkey. This research aimed to analyze the concentrations of Cu, Cd, Ni, Pb, Mn, and Zn by the use of Inductively Coupled Plasma Mass Spectrometry (ICP-MS). In addition, we computed the levels of chlorophyll a and b, and also determined the proportions of chlorophyll a+b, a/b, and b/a. Furthermore, a pollution map of the city was created. According to analysis results for P. furfuracea means of heavy metals; in first period 0.36μg g−1, 0,032μg g−1, 0,44μg g−1, 0,70μg g−1, 1,94μg g−1, 0,2 μg g−1; in second period 0,58μg g−1, 0,033μg g−1, 0,36μg g−1 ,0,92μg g−1 , 1,98μg g−1 , 0,65μg g−1 for Cu, Cd, Ni, Pb, Mn, Zn. Whereas means of control stations are 0,26 μg g−1, 0,028 μg g−1, 0,23μg g−1, 0,52μg g−1,1,90μg g−1, 0,16μg g−1, in 1st period; 0,36 μg g−1, 0,027μg g−1,0,29 μg g−1, 0,56μg g−1, 1,96μg g−1, 0,58 μg g−1 in 2nd period for for Cu, Cd, Ni, Pb, Mn, Zn. The factors that contribute to high heavy metal levels are as follows: (i) traffic density, (ii) industrial activities, (iii) urban heating activities. Despite the survey's short duration, P. furfuracea was proved to be an efficient bioaccumulator organism for further biomonitoring researches.

Chemical composition and trajectories of atmospheric particles at the Machu Picchu Peruvian Antarctic scientific station (62.09º S, 58.47º W)

Antarctica is a remote and relatively pristine region, but the regional transport of aerosols may be a source of pollution, especially in the Antarctic Peninsula. Few studies have characterized atmospheric aerosols and evaluated the contribution of their emission sources. The Peruvian Antarctic research station Machu Pichu (ECAMP, by its Spanish acronym) is located on King George Island in the Antarctic Peninsula. During February 2020, atmospheric particulate mass (PM10 and PM2.5) was sampled and analyzed to characterize its elemental composition and was supplemented by measurements of equivalent black carbon and aerosol size distributions. Chemical elements were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), multivariate techniques, and enrichment factors. The most abundant elements in PM10 and PM2.5 were Na, Fe, Mg, and Si, with the most important local sources being marine (Na, Mg, Mn, Ca) and crustal (Fe, Al, P). Sources of weathering (Ba and Si) from glacial thawing and sources of combustion linked to the use of oil (V) and emission of black carbon were recorded. Air mass back-trajectory analysis using the HYSPLIT model helped identify external sources of particulate matter in the air masses reaching the ECAMP site. Overall, this study supports the growing evidence of the anthropogenic impact of distant and local sources on the white continent.

Accumulation of absorbing aerosols over the Indian Sector of Southern Ocean during the austral summer: Role of thermal inversions

Optical properties of aerosols and their direct radiative effect were analyzed from columnar Aerosol Optical Depth (AOD) and ambient Black Carbon (BC) mass concentration (MB) estimated during Indian Southern Ocean Expeditions (SOEs), conducted in the austral summers of 2016–17 (SOE-IX) and 2017–18 (SOE-X). The aforementioned observations were supplemented with concurrent vertical soundings of the lower atmosphere. Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data aided in investigating the vertical distribution of aerosols up to 10 km altitude. The relative contribution of BC aerosols emanating from fossil fuel combustion and biomass burning showed the former to be predominant, as the latter is larger and preferentially scavenged during long-range transport to remote marine regions. The highest values of AOD at 500 nm (AOD500; 0.156 ± 0.026) and MB (90.78 ± 40.11 ng m−3) were encountered in the region between 50 and 60°S. Consequently, the atmospheric clear-sky Aerosol Direct Radiative Effect (ADRE; +3.10 ± 0.38 W m−2) and heating rate (HR; 0.087 ± 0.011 K day−1) were also observed to be the highest in the region. Multiple atmospheric inversions were detected between 40 and 69°S. Although a much lower AOD500 (0.070 ± 0.017) prevailed between 60 and 69°S, the average clear-sky ADRE (+1.56 ± 0.49 W m−2) and HR (0.044 ± 0.014 K day−1) were fairly high. The mean MB in the region was high (68.81 ± 28.40 ng m−3) for the pristine ice-covered region. Low-lying inversions prevented the vertical ventilation and dispersal of BC therein. Simulations of BC-induced atmospheric heating rates at three locations in the coastal Antarctic waters indicated a ≈ 3–5-fold increase, corresponding to an increase in ambient BC from 50 to 300 ng m−3.

Iodine oxoacids and their roles in sub-3 nm particle growth in polluted urban environments

Abstract. New particle formation contributes significantly to the number concentration of ultrafine particles (UFPs, d ≤ 100 nm) and has a great impact on human health and global climate. Iodine oxoacids (HIOx, including iodic acid, HIO3, and iodous acid, HIO2) have been observed in pristine regions and proved to dominate new particle formation (NPF) at some sites. However, the knowledge of HIOx in polluted urban areas is rather limited. Here, we conducted a long-term measurements of gaseous iodine oxoacids and sulfuric acid in Beijing from January 2019 to October 2021 and also in Nanjing from March 2019 to February 2020 and investigated the contribution of HIOx to UFP number concentration in both urban environments. HIO3 is highest in summer, up to 2.85 × 106 and 2.78 × 106 cm−3 in Beijing and Nanjing, respectively, and is lowest in winter by 96 % and 75 %, respectively. HIO3 exhibits more prominent variation than H2SO4 in both urban sites. HIO3 concentration shows a clear diurnal pattern at both sites with a daily maximum at around noontime, similar to the atmospheric temperature, solar radiation, and ozone (O3) levels. HIO2 concentration has the same diurnal and seasonal trend as HIO3 but is overall about an order of magnitude lower than HIO3 concentration. Back trajectory analysis suggests that the sources for inland iodine species could be a mix of marine and terrestrial origins, with both having peak iodine emission in warm seasons. While the contribution of HIO2 to particle growth is marginal in Beijing and Nanjing, our results demonstrate that HIO3 enhances the particle survival probability of sub-3 nm particles by about 40 % (median) and occasionally by more than 100 % in NPF events, suggesting HIOx are significant contributor to UFPs in polluted urban areas. As the growth contribution from HIO3 and H2SO4 is similar on a per-molecule basis, we propose that the sum of HIO3 and H2SO4 could be used to estimate sub-3 nm particle growth of inorganic acid origin in polluted atmospheres with a significant amount of HIOx.

Regional sources of NH3, SO2 and CO in the Third Pole

The Third Pole (TP) is a high mountain region in the world, and is well-known for its pristine environment, but recent development activities in the region have degraded its air quality. Here, we investigate the spatial and temporal changes of the air pollutants ammonia (NH₃), sulphur dioxide (SO₂) and carbon monoxide (CO) in TP, and reveal their sources using satellite measurements and emission inventory. We observe a clear seasonal cycle of NH3 in TP, with high values in summer and low values in winter. The intense agriculture activities in the southern TP are the cause of high NH₃ (6–8 × 1016 molec./cm2) there. Similarly, CO shows a distinct seasonal cycle with high values in spring in the southeast TP due to biomass burning. In addition, the eastern boundary of TP in the Sichuan and Qinghai provinces also show high values of CO (about 1.5 × 1018 mol/cm2), primarily owing to the industrial activities. There is no seasonal cycle found for SO₂ distribution in TP, but relatively high values (8–10 mg/m2) are observed in its eastern boundary. The high-altitude pristine regions of inner TP are also getting polluted because of increased human activities in and around TP, as we estimate positive trends in CO (0.5–1.5 × 1016 mol/cm2/yr) there. In addition, positive trends are also found in NH₃ (0.025 × 1016 molec./cm2/yr) during 2008–2020 in most regions of TP and SO₂ (about 0.25–0.75 mg/m2/yr) in the Sichuan and Qinghai region during 2000–2020. As revealed by the emission inventory, there are high anthropogenic emissions of NH3, SO2 and CO within TP. There are emissions of pollutants from energy sectors, oil and refinery, agriculture waste burning and manure management within TP. These anthropogenic activities accelerate the ongoing development in TP, but severely erode its environment.