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The Arctic is severely affected by climate change and various forms of environmental pollution. Enriched with nutrients and light-absorbing compounds, the wildfire plume has the potential to affect biological carbon fixation and sequestration within the Arctic Ocean. In this study, we utilized satellite-derived oceanic data (phytoplankton and sea ice) and atmospheric reanalysis products (black carbon, BC, indicative of wildfire impact) to evaluate the effect of the pronounced increase in wildfires from 2019 to 2021 on the East Siberian Sea. During these years, chlorophyll-a levels rose by ∼213 % compared to the previous decadal average, which had notably lower wildfire activities. This increase in chlorophyll-a is attributable to the deposition of nitrogen from the wildfire plume. Concurrently, the period required for sea ice concentration to decrease by 25 % was on average ∼ 10 days shorter than usual. This suggests that BC-induced acceleration of sea ice melting might extend the growing season for phytoplankton., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study investigated the carbonate system and air-sea CO 2 exchange in the inshore waters along South Korea's western coastline in 2020. Overlooking these waters might introduce significant errors in estimating air-sea CO 2 fluxes of the southeastern Yellow Sea, given their interaction with land, offshore regions, and sediments. During periods other than summer, seasonal variations in seawater CO 2 partial pressure (pCO 2 ) could be generally explained by thermal effects. Tidal mixing and shallow depths resulted in weaker stratification-induced carbon export compared to offshore regions. However, during summer, inshore waters exhibited high spatial variability in pCO 2 , ranging from approximately 185 to 1000 μatm. In contrast to offshore waters that modestly absorbed CO 2 , inshore waters shallower than 20 m emitted ∼100 Gg C yr -1 to the atmosphere. However, considering the high heterogeneity of the study area, additional observations with high spatial and temporal resolution are required to refine estimates of air-sea CO 2 exchange., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Atmospheric deposition of nitrogen is one of the most important external nutrient sources. We investigated the concentrations of NO 3 - and NH 4 + in airborne particles at both an offshore and an inshore site in the Yellow Sea. At the offshore site, devoid of local sources and located downwind from the highly developed areas of Korea and China, the concentrations of atmospheric particulate NO 3 - and NH 4 + were ∼88 ± 101 nmol m -3 and ∼102 ± 102 nmol m -3 , respectively, likely due to the transboundary long-range transport of pollutants. The inshore site showed a concentration ∼2 times higher than the offshore site. Considering not only dry inorganic nitrogen deposition but also wet and organic material deposition, the total atmospheric nitrogen deposition was estimated to contribute roughly 10 % to the new production in the Yellow Sea., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Accurately constraining the natural variability of the carbonate system is essential for evaluating long-term changes in coastal areas, which result from the absorption of anthropogenic CO 2 . This is particularly important given the significant variation in physical and biological processes in these regions. In this regard, the analysis of surface carbonate chemistry in the Yellow Sea was conducted using discrete seawater samples obtained from the Socheongcho Ocean Research Station (37.423°N, 124.738°E) between 2017 and 2022. Our bottle data and sensor pH measurements revealed considerable seasonal variations of aragonite saturation state (Ω AR ), typically ranging from 1.6 to 3.9. These variations are particularly pronounced during the summer and early winter. Our dataset serves as a baseline for understanding the long-term changes in ocean acidification in the Yellow Sea, the complex biogeochemical processes in coastal areas, and their impact on ocean acidification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Our understanding of the impact of atmospheric acid deposition on marine carbonate system remains limited, largely due to a lack of data regarding acidity present in atmospheric particles and precipitation. Previous research has relied on the electroneutrality-based ion balance method for indirect estimation of atmospheric acidity. In this study, atmospheric samples collected at a coastal site of South Korea were mixed with seawater to measure the change in seawater total alkalinity (ΔTA APL ) associated with atmospheric proton loading. For the precipitation samples, the measured ΔTA APL and electroneutrality-based estimates showed a significant correlation. However, we did not observe similar results for the atmospheric particle samples. Furthermore, the decrease in oceanic TA due to ΔTA APL was substantially smaller than that in dissolved inorganic carbon from concurrent nitrogen fertilization. Consequently, the adverse impact of acid deposition on ocean acidification or air-sea exchange of CO 2 appears to be insignificant on a short-term scale., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Surface carbonate chemistry in the Yellow Sea was investigated based on discrete seawater samples collected from 2017 to 2020 at the Socheongcho Ocean Research Station (S-ORS; 37.423°N, 124.738°E). Records of carbon parameters, including seawater CO 2 partial pressure (pCO 2 ), revealed considerable seasonal variations, with amplitudes comparable to those observed across the western part of the Yellow Sea. The study site acted as a modest sink (-0.13 mol C m -2  yr -1 ) for atmospheric CO 2 . Biological processes (primary production and respiration) and physical conditions (temperature and degree of stratification) determined seawater pCO 2 , which fluctuated on an intraseasonal timescale between oversaturated and undersaturated with respect to atmospheric pCO 2 . Variation in pCO 2 was significant in summer, depending on the biological carbon drawdown and tidal mixing-induced upwelling (increased pCO 2 up to ~1000 μatm). The intraseasonal variability in seawater pCO 2 may bias estimated air-sea CO 2 fluxes, if measurements with a coarser (seasonal) time resolution are used., (Copyright © 2022. Published by Elsevier Ltd.)

We evaluated the potential impacts of atmospheric deposition on marine productivity and inorganic carbon chemistry in the northwestern Pacific Ocean (8-39°N, 125-157°E). The nutrient concentration in atmospheric total suspended particles decreased exponentially with increasing distance from the closest land-mass (Asia), clearly revealing anthropogenic and terrestrial contributions. The predicted mean depositional fluxes of inorganic nitrogen were approximately 34 and 15 μmol m -2 d -1 to the west and east of 140°E, respectively, which were at least two orders of magnitude greater than the inorganic phosphorus flux. On average, atmospheric particulate deposition would support 3-4% of the net primary production along the surveyed tracks, which is equivalent to ~2% of the dissolved carbon increment caused by the penetration of anthropogenic CO 2 . Our observations generally fell within the ranges observed over the past 18 years, despite an increasing trend of atmospheric pollution in the source regions during the same period, which implies high temporal and spatial variabilities of atmospheric nutrient concentration in the study area. Continued atmospheric anthropogenic nitrogen deposition may alter the relative abundances of nitrogen and phosphorus., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)