Marine Atmosphere Research Articles

High heterogeneity and aging state of mineral particles in a slowly-moving dust plume on the southwestern coast of Japan

Aerosol particles in two size ranges, namely 0.18–1.4 μm (fine) and larger than 1.4 μm (coarse), were collected in the pre-dust, in-dust, and post-dust air during the passage of a slowly-moving dust event at a coastal site in southwestern Japan. We identified the composition and size of individual particles using a scanning electron microscope to investigate the variations during dust passage. The particles could be classified as mineral-seasalt mixtures, non-mixture minerals, sulfur-containing minerals, and seasalt particles, and the number fractions of these type particles in the two size ranges exhibited significant variation across the three periods. In the coarse size range, mixture particles accounted for 17.6 %, 26.8 %, and 37.8 % of the particles in the pre-dust, in-dust, and post-dust air, respectively. Non-mixture particles made up 36.8 %, 29.2 %, and 24.3 % in the same respective periods. In the in-dust air, the average relative ratio of sulfur content in sulfur-containing mineral particles in the coarse range was 5.5 %, whereas in the fine range, it was 17.2 %. The aging state of sea salt components, described by the Cl loss and reflecting the changes in particles due to chemical reactions, exhibited significant differences in the two size ranges. In the fine range, the aging of >90 % particles was predominantly influenced by sulfate formation in the in-dust air. In contrast, nitrate likely played a certain role in both the pre-dust and post-dust air. In the coarse range, the aging was independent of sulfate formation. These results indicate the close dependence of the aging of dust particles on their size and the notable variations of the aged states, underscoring the essentiality to treat dust particles properly according to time and space for a better understanding on their roles in the marine atmosphere.

Characterization of corrosion products formed on Q235 carbon steel and T2 copper in the Antarctic atmosphere

This study delves into the intricate corrosion behavior of ferrous and non-ferrous alloys in the challenging Antarctic marine atmosphere. Despite the harsh conditions and exceptionally low anthropogenic emissions in Antarctica, materials are still susceptible to severe corrosion. The investigation focuses on two materials: Q235 carbon steel and T2 copper. Both display distinct corrosion cases between their skyward and groundward sides due to the abrasive impact of persistent strong winds carrying ice particles and grit. Electrochemical reactions at the anode and cathode drive surface corrosion processes, involving Cl− and SO42−, ultimately leading to the formation of various corrosion products. The study highlights the role of sulfur-containing aerosols, Methanesulfonic acid (MSA) and non-sea-salt sulfate (nss-SO42-) in corrosion processes, as well as the interaction between Cl− and copper in forming corrosion products. The findings emphasize the complex interplay of environmental factors like wind, ice cover, and aerosols with materials, leading to diverse corrosion products and surface transformations. Further research is crucial to gain a comprehensive understanding of corrosion challenges in extreme environments like Antarctica and to develop effective mitigation strategies.

Probabilistic corrosion hazard maps for reinforced concrete infrastructure in coastal regions

The development of probabilistic corrosion hazard maps for reinforced concrete infrastructure exposed to airborne chlorides in coastal regions is addressed in the present work, with special attention to bridges. The methodology developed in this study consists of three steps. Initially, spatial distribution, construction year, and main features of the existing infrastructure are examined together with the general characteristics of the study area. The second step deals with the elaboration of relevant environmental data, including the direction and height of sea waves, sea salinity, temperature, relative humidity, rainfall, speed and direction of wind, and chloride deposition rates. Corrosion hazard maps are obtained next, wherein the corrosion current density is selected as an intensity measure. Particularly, they are elaborated for an assigned probability of exceedance given the exposure time window and concrete mixture. The presented methodology is applied to develop probabilistic corrosion hazard maps for reinforced concrete bridges exposed to the marine atmosphere at Oahu Island (Hawaii, United States). For this case-study, it is also discussed the correlation between the actual condition rating of the existing concrete bridges and the estimated corrosion hazard levels.

Long‐term atmospheric corrosion rates of Zn55Al‐coated steel

AbstractHot‐dip Zn55Al‐coated steel samples have been exposed for up to 6 years at 11 different weathering sites, including marine, marine‐industrial, acid‐rain and dry atmospheres. From the mass loss measurements, Zn55Al metallic coating showed globally long‐term good corrosion resistance in all weathering conditions compared with hot‐dip Zn‐0.2Al‐coated steel (Z). Yet, weaker performance was observed on Zn55Al in high SO2 polluted atmosphere, particularly when combined with seawater aerosols. This is explained by a more acidic surface condition linked to high SO2. Although the extent of corrosion in this phase was different at the different sites, the final corrosion products formed after 6 years were rather similar at all sites. This consists of hydrous aluminium sulphate or hydrous aluminium hydroxy sulphate and, probably also a smaller amount of sulphate‐containing zinc corrosion products or Al/Zn products.

Galvanic corrosion behavior of welded joint in marine atmosphere environment based on capillary microcell

The kinetical behavior and mechanism of micro-galvanic corrosion of Q690 bainitic weathering steel welded joint in marine atmosphere were investigated. The results showed that a micro-galvanic corrosion cell formed among different regions of the Q690 welded joint. The kinetical behavior of micro-galvanic corrosion could be divided into four stages: the initiation and development of micro-galvanic corrosion, the decreasing of galvanic corrosion rate, the polarity reversal of galvanic couple, and the disappearance of galvanic effect. The difference of corrosion rate between Q690 steel and its welded joint is closely related to the micro-galvanic corrosion kinetic behavior.

Analysis of concentrations of nitrate salts of PM2.5 in downwind marine atmospheres related to gas-particle partitioning and different sources in China

In order to explore the concentration characteristics and sources of major inorganic ions in marine atmospheric PM2.5, this study explores the concentration features of major inorganic ions in PM2.5 under the marine atmospheric observations of the offshore ~2000 km coastline of China in the downwind direction of the land-based sources. The observation results showed that the concentration of NO3- ranged from 0.03-10 μg m-3 with a variation of three orders of magnitude, and the main contributing species in PM2.5 was NO3- in the high concentration level observation period. The E-AIM results showed that NH3, HNO3 did not reach thermodynamic equilibrium with NH4+, NO3-, and ammonium nitrate was in volatile state, both during the day and at night. The results of the source analysis using PMF showed that there were three factors with identifiable contributions to NO3-, with Factor 1 considered to be a source of ship emissions, Factor 2 reflecting aerosols under low and medium pollution scenarios, and Factor 3 being aerosols under heavy pollution scenarios. Factor 3 was the main contributing source of NO3- concentration with a contribution of 84%, followed by Factor 2 (contribution of 15%) and the lowest contribution by Factor 1 (0.7%).

Temperature, humidity, and ionisation effect of iodine oxoacid nucleation.

Iodine oxoacids are recognised for their significant contribution to the formation of new particles in marine and polar atmospheres. Nevertheless, to incorporate the iodine oxoacid nucleation mechanism into global simulations, it is essential to comprehend how this mechanism varies under various atmospheric conditions. In this study, we combined measurements from the CLOUD (Cosmic Leaving OUtdoor Droplets) chamber at CERN and simulations with a kinetic model to investigate the impact of temperature, ionisation, and humidity on iodine oxoacid nucleation. Our findings reveal that ion-induced particle formation rates remain largely unaffected by changes in temperature. However, neutral particle formation rates experience a significant increase when the temperature drops from +10 °C to -10 °C. Running the kinetic model with varying ionisation rates demonstrates that the particle formation rate only increases with a higher ionisation rate when the iodic acid concentration exceeds 1.5 × 107 cm-3, a concentration rarely reached in pristine marine atmospheres. Consequently, our simulations suggest that, despite higher ionisation rates, the charged cluster nucleation pathway of iodic acid is unlikely to be enhanced in the upper troposphere by higher ionisation rates. Instead, the neutral nucleation channel is likely to be the dominant channel in that region. Notably, the iodine oxoacid nucleation mechanism remains unaffected by changes in relative humidity from 2% to 80%. However, under unrealistically dry conditions (below 0.008% RH at +10 °C), iodine oxides (I2O4 and I2O5) significantly enhance formation rates. Therefore, we conclude that iodine oxoacid nucleation is the dominant nucleation mechanism for iodine nucleation in the marine and polar boundary layer atmosphere.

A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere

To assess dynamic loads, large offshore wind turbines need detailed and reliable statistical information on the inflow turbulence. We present a model that includes low frequencies down to ∼1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim 1$$\\end{document} hr-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{-1}$$\\end{document} using the observed S(f)∝f-5/3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$S(f) \\propto f^{-5/3}$$\\end{document} in that range. The presented model contains a parameter representing the anisotropy of the two-dimensional, incompressible turbulence, and it assumes the low-frequency fluctuations to be homogeneous in the vertical direction. Combined with a three-dimensional model for the smaller scales, the model can predict correlations between different points. We have validated the model against two offshore wind data sets: a nacelle-mounted, forward-looking Doppler lidar with four beams at the Hywind Scotland offshore wind farm and sonic anemometer measurements at the FINO1 research platform in the North Sea. One-point auto spectra and two-point cross spectra were calculated after splitting the data into different atmospheric stability classes. The relative strength of the 2D low-frequency fluctuations to the 3D fluctuations was higher under stable conditions. The combined 2D+3D model was able to fit the measured spectra with good accuracy and could then predict the two-point cross spectra, co-coherences, and phase angles between wind fluctuations at different lateral and vertical separations. Good agreement was found between the measured and predicted values, albeit with exceptions. The model can generate stochastic wind fields for investigating wake meandering in wind farms or dynamic loads on floating wind turbines.

Propagation properties of one-dimensional array vortex beams in a marine atmosphere

Propagation properties of one-dimensional array vortex beams in a marine atmosphere

The vital role of sulfuric acid in iodine oxoacids nucleation: impacts of urban pollutants on marine atmosphere

The nucleation of iodic acid (HIO3) and iodous acid (HIO2) play a significant role in marine new particle formation (NPF) events. However, the inability to explain intensive NPF bursts in polluted coasts indicates the participation of potential precursors. Herein, we identified a novel nucleation mechanism of HIO3–HIO2 system enhanced by the urban pollutant sulfuric acid (H2SO4). We found that H2SO4 could largely enhance the cluster formation rates (J, cm−3 s−1) of HIO3–HIO2 system, especially in high [H2SO4] regions near H2SO4 emission sources. The enhanced J of HIO3–HIO2–H2SO4 system performs better match than that of HIO3–HIO2 system with the observational rates of polluted coasts and polar regions, such as Zhejiang and Marambio. Moreover, the H2SO4-involved cluster formation is realized without Gibbs free energy barrier and dominate broadly in marine regions with rich H2SO4 and scarce iodine concentrations. These findings may help to explain some missing fluxes of marine new particles and emphasize the impact of urban components on marine nucleation processes.

Bubble-mediated generation of airborne nanoplastic particles.

Micro- and nanoplastic particles have been detected in most environmental compartments. The presence of microplastics in the remote marine atmosphere and close to large lakes suggests bubble mediated water-air transfer as a source of airborne microplastics, however, quantitative estimates of plastic emission from surface waters remain uncertain. In this work, we elucidate the emission of submicron polystyrene nanospheres by bubble bursting in a laboratory setting from low salinity waters (salinity 0-1.0 g kg-1), polystyrene particle diameter (103, 147 and 269 nm), aqueous particle number concentrations in the range 4 × 107-2 × 109 cm-3, and bubble formation rate (0.88-3.35 L min-1 of air). Production of polystyrene aerosols was demonstrated using a scanning mobility particle sizer and confirmed by analysis of filter samples using pyrolysis gas chromatography coupled to mass spectrometry. We show that production of polystyrene aerosol particles scales linearly with the number concentration of plastic particles in the water. Our results suggest that small amounts (0.01 g kg-1) of salt increase polystyrene particle production. To the best of our knowledge this is the first study of bubble mediated water-air transfer of plastic particles as small as 100 nm.

(Invited) The Internal Oxidation Mechanism of Ti60 Alloy in NaCl-coated Environment at 600o C

When serving in the marine environment, the blades of aircraft engines will suffer serious high-temperature corrosion and their service life will be shortened. This is because the water vapour and salt particles (mainly NaCl) in the marine atmosphere will inevitably be involved in the engine, resulting in severe corrosion of materials. Previous studies on the degradation of titanium alloy under NaCl mainly focused on the active oxidation mechanism, while the mechanism of internal oxidation, which can significantly damage the mechanical properties of the titanium, is not clear. In addition, internal oxidation appears microstructure sensitivity, indicating that microstructure design may be an important way to improve high-temperature corrosion resistance in the marine environment.Consequently, for further understanding the internal oxidation mechanism and the influence of microstructure on corrosion, the composition and morphology of the internal oxidized layer of the Ti60 samples, which corroded with NaCl precoated at 600 oC in moist O2 flow for 100 h, have been studied.According to the results, Ti2O formed within the internal oxidized layer. With the thermodynamic calculation results, this observation proves that internal oxides do not result from the oxidation of metal chlorides. As it is known that titanium has a high affinity to oxygen, the internal matrix turns into titanium oxides with different valence states directly, while TiCl4(g) formed from active oxidation further transports outward and is oxidized at the position with high P(O2).The α secondary phase, located inside the β phase, is more sensitive to NaCl-induced corrosion than the α lamellar outside the β phase. This is because β phase and phase boundaries provide more high-energy channels for corrosive media transport to the α secondary phase, which results in severe loss of metallic elements and oxidation. The design of the α secondary phase may be one essential point for developing titanium alloys with a good combination of mechanical properties and corrosion resistance in marine environments. Figure 1

HIO3-HIO2-Driven Three-Component Nucleation: Screening Model and Cluster Formation Mechanism.

Iodine oxoacids (HIO3 and HIO2)-driven nucleation has been suggested to efficiently contribute to new particle formation (NPF) in marine atmospheres. Abundant atmospheric nucleation precursors may further enhance HIO3-HIO2-driven nucleation through various multicomponent nucleation mechanisms. However, the specific enhancing potential (EP) of different precursors remains largely unknown. Herein, the EP-based screening model of precursors and enhancing mechanism of the precursor with the highest EP on HIO3-HIO2 nucleation were investigated. The formation free energies (ΔG), as critical parameters for evaluating EP, were calculated for the dimers of 63 selected precursors with HIO2. Based on the ΔG values, (1) a quantitative structure-activity relationship model was developed for evaluating ΔG of other precursors and (2) atmospheric concentrations of 63 (precursor)1(HIO2)1 dimer clusters were assessed to identify the precursors with the highest EP for HIO3-HIO2-driven nucleation by combining with earlier results for the nucleation with HIO3 as the partner. Methanesulfonic acid (MSA) was found to be one of the precursors with the highest EP. Finally, we found that MSA can effectively enhance HIO3-HIO2 nucleation at atmospheric conditions by studying larger MSA-HIO3-HIO2 clusters. These results augment our current understanding of HIO3-HIO2 and MSA-driven nucleation and may suggest a larger impact of HIO2 in atmospheric aerosol nucleation.

Observational Evidence of Unknown NOx Source and Its Perturbation of Oxidative Capacity in Bermuda's Marine Boundary Layer

AbstractNitrogen oxides (NOx) are key intermediates in the atmospheric cycling of reactive nitrogen, the spatiotemporal distribution of which modulates ozone (O3) production. Field campaigns were conducted at the Tudor Hill Marine Atmospheric Observatory, Bermuda, in the spring and summer of 2019 to explore atmospheric cycling of NOx and its modulation of photochemical O3 production in the marine boundary layer. In aged, clean marine air, an atypical NO2 diel profile with a solar noon peak of 69 ± 5 pptv was recorded, challenging the classic U‐shaped diel profile with a solar noon valley characterized by fast photolysis and oxidation consumption in the daytime. This result indicated an unknown daytime NOx source excluded from the current near‐explicit chemical model, which underestimated the solar noon NOx level by 20–56 pptv and source rate by 9.7–33.5 pptv hr−1, considering the upper and lower limits of total OH reactivity and halogen photochemistry in the marine boundary layer. The observed HONO level accounted for ∼56% of the unknown NOx source, implying an unknown NOx regeneration pathway with HONO as an intermediate. The photochemical nature of the unknown NOx source maximized perturbation of photochemical OH and O3 production. The O3 abundance and production rate were underestimated by 2–4 ppbv and 28%–80%, respectively, and the OH abundance and source rate were 7%–55% and 21%–57% lower than the estimated levels with the constraint of NOx, respectively. The unknown NOx source requires urgent revision of the current understanding of reactive nitrogen cycling and the oxidative capacity of the clean marine atmosphere.

Logan Medallist 8. Trace Elements in Iron Formation as a Window into Biogeochemical Evolution Accompanying the Oxygenation of Earth’s Atmosphere

Iron formations exemplify a type of sedimentary rock found in numerous Archean and Proterozoic supracrustal successions. They serve as a valuable chemical record of Precambrian seawater chemistry and post-depositional iron cycling. These formations accumulated on the seafloor for over two billion years during the early history of our planet, offering a unique opportunity to study environmental changes that occurred during Earth's evolution. Among these changes, one of the most significant events was the shift from an anoxic planet to one where oxygen (O2) became consistently present in both the marine water column and atmosphere. This progression towards global oxygenation was closely linked to the emergence of aerobic microbial metabolisms, which profoundly impacted continental weathering processes, nutrient supply to the oceans, and ultimately, the diversification of the biosphere and complex life forms. In this review, we synthesize two decades of research into the temporal fluctuations of trace element concentrations in iron formations. Our aim is to shed light on the complex mechanisms that contributed to the oxygenation of Earth's surface environments.

Elucidating the effect of titanium alloying on the pitting corrosion of ferritic stainless steel

Ferritic stainless steels have been utilized in marine atmosphere and are found to be susceptible to pitting corrosion in our field investigation. Alloying is an important to modify the passive film on the surface and improve the pitting corrosion resistance. Nevertheless, how the addition of titanium modifies the passive film and affects the pitting corrosion resistance of ferritic stainless steels remain controversial. This study has elucidated these topics through microstructure analysis and corrosion properties analysis. The results demonstrate that titanium addition increases the pitting potential almost linearly. Titanium forms TiO2 in the passive film and reduces defect density of the passive film. Moreover, titanium addition induces the precipitation of the Laves phase, which promotes micro-galvanic corrosion. For the titanium-alloyed ferritic stainless steels, pitting corrosion predominantly occurs in the ferrite phase adjacent to the Laves phase. The influence mechanism of titanium on the pitting corrosion of the ferritic stainless steel has been established, which takes micro-galvanic corrosion induced by titanium addition into account.

Root cause of corrosion failure of tin coating on wire clamp in marine atmosphere

Root cause of corrosion failure of tin coating on wire clamp in marine atmosphere

Corrosion failure analysis of engineering structural steels in tropical marine atmospheres: A comparative study of ordinary and new weathering steels

Reliable applications for weathering steels face challenges in harsh tropical marine atmospheric environments. The development of new weather steel suitable for tropical marine atmospheric environments is of great significance. In the paper, the corrosion failure behavior of ordinary and newly designed weathering steels exposed to tropical marine environments for two years was studied by employing various analytical methods. The results indicate that the extensive formation of akaganeite and lepidocrocite occurs deep inside the abnormally thick corrosion products of ordinary weathering steel with the accumulation of Cl−, which is laborious to be affected by the rinsing effect of rainfall. Based on the study of the composition, phase, and structure of abnormally thick corrosion products, a chain evolution mechanism of corrosion failure is proposed. By optimizing the content of Cu, Mo, and Ni, the newly designed weathering steel can effectively suppress the chain failure process and increase the corrosion resistance by approximately doubling. On the whole, the newly designed weathering steel can be well applied to tropical marine atmospheric environments.

Evidence of nitrate-based nighttime atmospheric nucleation driven by marine microorganisms in the South Pacific.

Our understanding of ocean-cloud interactions and their effect on climate lacks insight into a key pathway: do biogenic marine emissions form new particles in the open ocean atmosphere? Using measurements collected in ship-borne air-sea interface tanks deployed in the Southwestern Pacific Ocean, we identified new particle formation (NPF) during nighttime that was related to plankton community composition. We show that nitrate ions are the only species for which abundance could support NPF rates in our semicontrolled experiments. Nitrate ions also prevailed in the natural pristine marine atmosphere and were elevated under higher sub-10 nm particle concentrations. We hypothesize that these nucleation events were fueled by complex, short-term biogeochemical cycling involving the microbial loop. These findings suggest a new perspective with a previously unidentified role of nitrate of marine biogeochemical origin in aerosol nucleation.

Effect of La on the Corrosion Behavior and Mechanism of 3Ni Weathering Steel in a Simulated Marine Atmospheric Environment

Effect of La on the Corrosion Behavior and Mechanism of 3Ni Weathering Steel in a Simulated Marine Atmospheric Environment