Evidence for Fossil Fuel PM1 Accumulation in Marine Biota

Quantification of uncertainty in short-term tropospheric column density risks for a wide range of carbon monoxide

The short-term risks associated with atmospheric trace gases, particularly carbon monoxide (CO), are critical for ecological security and human health. Traditional statistical methods, which still dominate the assessment of these risks, limit the potential for enhanced accuracy and reliability. This study evaluates the performance of traditional models (ARIMA), machine learning models (LightGBM, ConvLSTM2D), and optimized machine learning solutions (Bayes residual optimization ConvLSTM2D LightGBM, Bayes_CL) in predicting Sentinel 5P columnar CO levels. This study findings demonstrate that machine learning models and their optimized versions significantly outperform traditional ARIMA models in cross-validation (CV), visualization, and overall prediction performance. Notably, machine learning model based on Bayes and residual optimization (Bayes_CL) achieved the highest CV score (Bayes_CL R2 = 0.8, LightGBM R2 = 0.79, ConvLSTM2D R2 = 0.75, ARIMA R2 = 0.61), along with superior visualization and other metrics. Using Bayes_CL, we effectively quantified a 2.4% increase in columnar CO levels in mainland China in the second half of 2023, following the complete lifting of COVID-19 lockdowns. This study confirms that machine learning models can effectively replace traditional methods for short-term risk assessment of Sentinel 5P columnar CO. This transition holds significant implications for policy formulation, greenhouse effect assessment, and population health risk evaluation, especially in uncertain situations where human activities are severely disrupted, thereby affecting environmental safety.

Temporal variations and chemical characteristics of marine PM2.5 at Dongsha Islands, South China Sea: Three-year measurement

The study of long-range transport effects on marine fine particles (PM2.5), particularly in remote sites such as the Dongsha Islands, is pivotal for advancing our understanding of air pollution dynamics on a regional scale and for formulating effective environmental policies. PM2.5 concentrations were examined over three consecutive years and grouped based on their transport routes. The backward trajectory simulation revealed that high PM2.5 concentrations were observed in the West Channel, originating from North and Central China, the Korean Peninsula, and the Japanese Islands, opposed to the East Channel. High PM2.5 concentrations, commonly observed in winter and spring, were mainly attributed to the Asian Northeastern Monsoons. Water-soluble inorganic ions constituted the major components, accounting for 37.8-48.7% of PM2.5, and followed by metal elements (15.5-20.0%), carbons (7.5-13.3%), levoglucosan (0.01-0.17%), and organic aerosols (0.2-2.2%). Secondary inorganic aerosols as the dominant source accounted for 8.3-24.7% of PM2.5, while sea salts were the secondary major contributor. High levoglucosan contribution (3.8-7.2%) in winter and spring was attributed to biomass burning, mainly from the Indochina Peninsula. Chemical mass balance receptor modeling resolved that major sources of PM2.5 were secondary sulfate, sea salts, fugitive dust, and industrial boilers. This study concluded that the long-range transport of PM2.5 gradually increased since fall, contributing 52.1-74.3%, highlighting its substantial impact on PM2.5 in all seasons except summer.

Atmospheric deposition as a direct source of particulate organic carbon in region coastal surface seawater: Evidence from stable carbon and nitrogen isotope analysis

To assess the source characteristics of coastal aerosols and evaluate the contribution of atmospheric deposition to particulate organic matter in surface seawater, total suspended particulates (TSP) were collected at a shore-based site on the south coast of North Yellow Sea from December 2019 through November 2020. The samples were analyzed for total organic carbon (TOC) and nitrogen (TN) as well as stable carbon and nitrogen isotope (δ13C and δ15N). The results showed that the annual mean concentrations of TOC and TN were 5.36 ± 4.74 and 5.12 ± 6.52 μg m-3, respectively. δ13C fluctuated between -25.1 ‰ and -19.2 ‰ with an annual mean of -24.0 ± 1.0 ‰ and a significant seasonal variation (P < 0.05) characterizing by the enrichment in winter (-23.4 ± 0.6 ‰) compared to other seasons, which was probably related to the massive coal combustion. Besides, δ15N ranged from 7.9 ‰ to 21.1 ‰ with an annual mean of 12.5 ± 2.9 ‰ and a less pronounced seasonal pattern (P = 0.23). The Bayesian isotope-mixing model showed that, annually, the most important source of TSP was biogenic and biomass source (55.5 ± 10.8 %), followed by fossil fuel combustion (31.9 ± 9.0 %), while the marine contribution was less (12.6 ± 2.3 %). For TOC and TN, the dominated sources were fossil fuel combustion (47.7 ± 3.4 %) and biogenic and biomass source (57.3 ± 11.7 %), respectively. Furthermore, the model results indicated that the contribution of atmospheric deposition to suspended particulate matter in surface seawater was 18.0 ± 11.0 %, 17.1 ± 6.7 % and 10.2 ± 2.0 % in autumn, spring and summer, respectively. For particulate organic carbon in surface seawater, the contribution of atmospheric deposition was 35.2 ± 3.5 % in spring, highlighting the huge impact of atmospheric deposition on particulate carbon cycling in coastal waters.

Inter-comparison of chemical fingerprint and source apportionment of marine fine particles at two islands through the west and east passages of the Taiwan Island

In this study, the concentrations of marine fine particles (PM_2.5) and their chemical fingerprints were inter-compared at two islands located aside from the west and east waters of Taiwan Island and the variability of west and east passages (i.e., Routes A1 and A2) were explored. Marine PM_2.5 was simultaneously sampled at the Green and Dongsha Islands and five chemical components (i.e., water-soluble ions, metallic elements, carbonaceous content, anhydrosugars, and organic acids) were further analyzed in PM_2.5 to characterize their chemical fingerprints. The highest concentrations of chemical composition and PM_2.5 were commonly observed during the Asian Northeastern Monsoons (ANMs) via long-range transport (LRT). Water-soluble ions (WSIs) were dominated by secondary inorganic aerosols (SIAs), and followed by oceanic spray. The major metallic content of PM_2.5 was crustal elements, while trace metals originated from anthropogenic sources with an enrichment factor (EF) > 10. In terms of carbonaceous content in PM_2.5, organic carbon (OC) was superior to elemental carbon (EC). High levoglucosan concentrations were also observed during the periods of ANMs. Secondary organic aerosols (SOAs) were formed by atmospheric chemical reactions during the LRT procedure. The PM_2.5 concentration of Route A1 was 37.51 % higher than that of Route A2, and trace metals (V, Mn, Ni, Pb, Cr, and Cu) increased significantly by 96.16-325.83 %. Positive matrix factorization (PMF) results revealed that the dominant factor of PM_2.5 for Route A1 was shipping emissions and vehicular exhausts (41.2 %), while that for Route A2 was oceanic spray (30.2 %). Route A1 was mainly attributed to highly industrialized regions, densely populated urbanized areas, and ship-intensive traffics in East Asia.

Detrimental impact of fine dust on zebrafish: Investigating a protective agent against ocular-damage using in vitro and in vivo models

Pollution caused by fine dust is becoming a global problem in the aquatic environment. Many studies have investigated the hazards that fine dust may pose to terrestrial organisms; however, information on the effects on aquatic environments remain limited. In this study, the physicochemical characteristics of the fine dust associated with the captured powder or liquid state were compared using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). Raw fine dust (RFD), in the captured powder state, was suspended in water (SFD), and the elemental composition, morphology, and size distribution of both were analyzed. Zebrafish were used as a model to study the effects of SFD-exposure on aquatic organisms. A fatal malformation was observed in the integuments of zebrafish exposed to SFD, specifically in the exterior and interior eye tissues. Furthermore, the exposure of SFD to Tg (flk; EGFP) zebrafish remarkably increased ocular vessel diameter expansion along with blood flow velocity. Regarding vessel diameter expansion, EA.hy926 cells exposed to SFD were adversely affected, with a significant increase in cell migration and capillary-like structure formation, which are angiogenic markers. The SFD-induced angiogenesis in vitro and in vivo was dramatically restored to normal via α/β-adenosine isolated from the anti-angiogenic brown algae Ishige okamurae extract. Taken together, the current study presents solid evidence of the altered physicochemical characteristics of SFD compared to RFD, and the detrimental impact of SFD in an aquatic in vivo zebrafish model. In addition, the protective effect of α/β-adenosine, a marine natural product, on SFD-induced angiogenesis suggests that it can be used as an agent to reduce the adverse effects of SFD on aquatic animals.

Transport route-based cluster analysis of chemical fingerprints and source origins of marine fine particles (PM2.5) in South China Sea

The fingerprints and source origins of marine PM_2.5 at two background islands in the South China Sea were clustered via trajectory analysis and positive matrix factorization. High PM_2.5 concentrations at the Dongsha Islands occurred for the north routes, while Nansha Islands had similar PM_2.5 concentrations amongst the transport routes. However, the chemical characteristics of PM_2.5 varied with the transport routes. Secondary inorganic aerosols (NO₃^-, SO₄^2-, and NH₄⁺) were abundant in water-soluble ions which dominated PM_2.5. Crustal metals were the abundant metals in PM_2.5, while trace metals were primarily originated from man-made sources. Organic carbon was superior to elemental carbon, and high concentrations of levoglucosan and organic acids were observed for the north routes. Overall, marine PM_2.5 at the Dongsha Islands was highly influenced by long-range transport of Asian continental outflows, while particulate air quality at the Nansha Islands was mainly governed by clean air parcels blown from the SCS.

Deposition of Aerosols onto Upper Ocean and Their Impacts on Marine Biota

Atmospheric aerosol deposition (wet and dry) is an important source of macro and micronutrients (N, P, C, Si, and Fe) to the oceans. Most of the mass flux of air particles is made of fine mineral particles emitted from arid or semi-arid areas (e.g., deserts) and transported over long distances until deposition to the oceans. However, this atmospheric deposition is affected by anthropogenic activities, which heavily impacts the content and composition of aerosol constituents, contributing to the presence of potentially toxic elements (e.g., Cu). Under this scenario, the deposition of natural and anthropogenic aerosols will impact the biogeochemical cycles of nutrients and toxic elements in the ocean, also affecting (positively or negatively) primary productivity and, ultimately, the marine biota. Given the importance of atmospheric aerosol deposition to the oceans, this paper reviews the existing knowledge on the impacts of aerosol deposition on the biogeochemistry of the upper ocean, and the different responses of marine biota to natural and anthropogenic aerosol input.

Black Carbon as a Source of Trace Elements and Nutrients in Ice Sheet of King George Island, Antarctica

Enormous deglaciation in the polar and mountainous regions of the Earth is associated not only with large-scale climatic changes but also with the global transfer of black carbon (BC) microparticles, which accumulate on the surface of glaciers and lead to changes in albedo and the rate of degradation of ice. BC is the product of an incomplete combustion of fossil fuels, volcanic eruptions, and wildfires. The accumulation of organogenic microparticles leads to the formation of cryoconites, which are dust made of a combination of small rock particles and the result of anthropogenic activities (fossil fuel combustion) that play a special role in deglaciation. Here, we describe the content of trace metals and nutrients in accumulation of the BC from glaciers of Fildes Peninsula, King George Island, Western Antarctica. The analysis of trace metals concentrations showed that most of the studied elements (Cr, Pb, Zn, Ni) have a volcanic origin; at the same time, Cd and Cu have been accumulated as a result of anthropogenic activity. The content of nutrients in BC are most similar with Technosols, which forms near the scientific station at King George Island. The particles of BC can be translocated into organisms, which could pose a significant risk for living organisms and humans.