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This study aims to investigate the seasonal variation and source identification of fluorescent aerosol particles at the monitoring site of the University of Salento in Lecce, southeastern Italy. Utilizing a wideband integrated bioaerosol sensor (WIBS), this research work analyzes data from two specific monitoring days: one in winter (10 January 2024), marked by significant transport of anthropogenic particles from Eastern Europe, and another in early spring (6 March 2024), characterized by marine aerosol sources and occasional desert dust. This study focuses on the seven WIBS particle categories (A, B, C, AB, AC, BC, ABC), which exhibited distinct characteristics between the two days, indicating different aerosol compositions. Winter measurements revealed a predominance of fine-mode particles, particularly soot and bacteria. In contrast, spring measurements showed larger particles, including fungal spores, pollen fragments, and mineral dust. Fluorescence intensity data further emphasized an increase in biological and organic airborne material in early spring. These results highlight the dynamic nature of fluorescent aerosol sources in the Mediterranean region and the necessity of continuous monitoring for air quality assessments. By integrating WIBS measurements with air mass back-trajectories, this study effectively identifies fluorescent aerosol sources and their seasonal impacts, offering valuable insights into the environmental and health implications of aerosol variability in the investigated Mediterranean area. [ABSTRACT FROM AUTHOR]

Marine aerosol particles can act as cloud condensation nuclei and influence the atmospheric boundary layer by scattering solar radiation. The interaction of ocean waves and coral reefs may affect the distribution and size of marine aerosol particles. Measuring this effect has proven challenging. Here, we tested the hypothesis that the distribution and size of marine aerosol particles would vary over three distinct zones (i.e., coral lagoon, surf break, and open water) near One Tree Island in the Great Barrier Reef, which is approximately 85 km off the east coast of Australia. We used a modified DJI Agras T30 drone fitted with a miniaturised scanning electrical mobility sizer and advanced mixing condensation particle counter to collect data on aerosol size distribution between 30 and 300 nm at 20 m above the water surface. We conducted 30 flights over ten days during the Austral summer/autumn of 2023. The fitted bimodal lognormal curves indicate that the number concentrations for aerosols below 85 nm diameter are more than 16% higher over the lagoon than over open water. The average mean mode diameters remained constant across the different zones, indicating no significant influence of breaking waves on the detected aerosol size modes. The most influential explanatory variable for aerosol size distribution was the difference between air temperature and the underlying sea surface, explaining around 40% of the variability. Salinity also exhibited a significant influence, explaining around 12% of the measured variability in the number concentration of aerosols throughout the campaign. A calculated wind stress magnitude did not reveal significant variation in the measured marine aerosol concentrations. Overall, our drone-based aerosol measurements near the water surface effectively characterise the dynamics of background marine aerosols around One Tree Island Reef, illustrating the value of drone-based systems for providing size-dependent aerosol information in difficult-to-access and environmentally sensitive areas.

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. [ABSTRACT FROM AUTHOR]

Atmospheric particles from different sources can impact cloud formation and play a critical role in regulating cloud properties. However, particle characteristics at single particle level and their abilities to serve as ice nucleating particles (INPs) over different marine atmosphere are poorly understood. Here, we present characterizations and ice nucleation properties of particles collected during a northern and southern hemisphere cruise from South Korea to Antarctica. Micro-spectroscopic analysis was used to obtain composition of individual particles and mixing state of particle populations. Major particle classes were identified and have different contributions over the Western Pacific and the Southern Ocean, including fresh and aged sea salt, sea salt mixed with sulfate, carbonaceous, sulfur-containing, and dust particles. Increasing contribution of fresh sea salt particles, the dominate particle class in the samples, tended toward an increasing mixing state index indicating the population becoming more internally mixed. Aging processes and new particle sources introduce particles with new compositions resulting in external mixtures. We found that the investigated particles demonstrated a variety of ice nucleation abilities at cirrus conditions. The identified INPs are all major particle classes present in the population, and the sea salt mixed sulfate particle is enriched in INPs. Aging processes affected both particle mixing state and their ice nucleation abilities. We tested different ice nucleation parameterizations of marine atmospheric particles for their applicability. Finally, we discuss how the mixing state of particle populations impacts ice nucleation in the atmosphere. [ABSTRACT FROM AUTHOR]

Dimethyl sulfide (DMS), emitted from the oceans, is the most abundant biological source of sulfur to the marine atmosphere. Atmospheric DMS is oxidized to condensable products that form secondary aerosols that affect Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report the atmospheric discovery of a previously unquantified DMS oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), identified through global-scale airborne observations that demonstrate it to be a major reservoir of marine sulfur. Observationally constrained model results show that more than 30% of oceanic DMS emitted to the atmosphere forms HPMTF. Coincident particle measurements suggest a strong link between HPMTF concentration and new particle formation and growth. Analyses of these observations show that HPMTF chemistry must be included in atmospheric models to improve representation of key linkages between the biogeochemistry of the ocean, marine aerosol formation and growth, and their combined effects on climate.

This work addresses the chemical characterization of atmospheric aerosols and precipitation in the period from May to November 2019 at Monte Fenton (53.16° S, 71.05° W, 612 m.a.s.l.), 9 km west of Punta Arenas, to study the contribution and distribution of emission sources and chemical enrichment. The main ions (Ca2+, Cl−, K+, Mg2+, Na+, NH4+, NO3− and SO42−) were studied using ion chromatography, and trace elements (Al, Br, Ca, Cl, Cr, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Se, Si, Ti, V and Zn) using energy dispersive X-ray fluorescence. Ions concentration ranged from 5.0 × 10−1 to 2.9 × 104 mg/m3 for Ca2+ and Cl−, respectively; whilst the concentration of elements varied between 8.8 × 10−11 and 2.1 × 10−2 mg/m3, for crZn (crustal Zn) and Fe, respectively. The electrical conductivity (EC, mean = 32.5 µS/cm) and the pH (mean = 6.8), showed the atmosphere of the study site was relatively neutral compared to the standard pH for rain (or snow) without contamination (pH = 5.6), and presented relatively low levels of conductivity compared to the EC standards for distilled water (0.5 to 3 µS/cm) and seawater (30,000 to 60,000 µS/cm). The main contribution to aerosols in the atmosphere of Monte Fenton came from marine and lithospheric sources, followed by local anthropogenic sources such as burning firewood and/or urban waste for heating production, etc., that led to the enrichment of aerosols with high Fe, K, Mn and V content. The results of this study contribute to filling a gap in knowledge of the chemistry of atmospheric aerosols in Southern Patagonia. [ABSTRACT FROM AUTHOR]

The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is an interdisciplinary investigation to improve understanding of Earth's ocean ecosystem-aerosol-cloud system. Specific overarching science objectives for NAAMES are to (1) characterize plankton ecosystem properties during primary phases of the annual cycle and their dependence on environmental forcings, (2) determine how these phases interact to recreate each year the conditions for an annual plankton bloom, and (3) resolve how remote marine aerosols and boundary layer clouds are influenced by plankton ecosystems. Four NAAMES field campaigns were conducted in the western subarctic Atlantic between November 2015 and April 2018, with each campaign targeting specific seasonal events in the annual plankton cycle. A broad diversity of measurements were collected during each campaign, including ship, aircraft, autonomous float and drifter, and satellite observations. Here, we present an overview of NAAMES science motives, experimental design, and measurements. We then briefly describe conditions and accomplishments during each of the four field campaigns and provide information on how to access NAAMES data. The intent of this manuscript is to familiarize the broad scientific community with NAAMES and to provide a common reference overview of the project for upcoming publications.

In order to determine the nature of the high salinisation rate of the waters of Lake Sidi Boughaba, which has been listed in the Ramsar list since 1980, 23 samples that were taken during four sampling operations were subjected to physicochemical analyses. The obtained results were processed using a combination of bi-varied methods (correlation tests) and multivariate statistical methods (principal component analysis - PCA). The physicochemical analyses reveal that they are alkaline waters with a pH ranging between 8.38 and 9.03, an electrical conductivity (EC) of the order of 12.4 to 17.4 mS⋅cm-1, and high levels of Na+ and Cl-, up to 3700 and 6630 mg⋅dm-3 respectively, indicating a marine origin of these waters. In addition, the statistical treatment revealed that the mineralisation of the waters of this ecosystem is controlled by four main mechanisms of the salinisation; the main mechanism underlying this strong mineralisation is due to the impact of the marine spray. The second-order processes are about the phenomenon of the ion exchange, the dissolution/precipitation of evaporitic and carbonate formations, the oxidation-reduction processes, notably the reduction of sulphates as well as biochemical phenomena due to the selective absorption of certain ions by fauna and flora. [ABSTRACT FROM AUTHOR]

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using "dry" geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.

Aerosols play an important role in the Earth–atmosphere system. Their impacts on the weather and climate are highly dependent on spatiotemporal distributions as well as physical-optical properties. Physical-optical properties of the aerosols over the Asian continent have been widely investigated, but there are relatively few observations in maritime locations, especially the South China Sea (SCS). Here, with the combination of in situ ship-based observations from June and July 2019 as well as long-term MERRA-2 reanalysis datasets from January 2012 to December 2021, the physical and optical properties of marine aerosols in the SCS are explored. The impacts of meteorological factors, particularly frontal systems, on the aerosol properties are further analyzed based on detailed observations. The observed results show that aerosols are vertically concentrated below 3 km and the extinction coefficient reaches the maximum value of 0.055 km−1 near 480 m. Moreover, the particles are composed of an accumulation and a coarse particle mode, and they conform to the lognormal distribution. The synoptic-scale case study demonstrates that both the cold front and stationary front lead to an increase in aerosol optical thickness (AOD), which is due to the enhanced wind speed and the hygroscopic growth of fine particles, respectively. The long-term analysis indicates that AOD decreases from northwest to southeast with the increasing distance away from the continent, and it reflects higher values in spring and winter than in summer and autumn. Sulfate and sea salt dominate AOD in this region when compared with other components. The overall AOD shows a significant negative trend of −0.0027 year−1. This work will help us further understand the physical and optical properties of marine aerosols over the SCS and then contribute to quantifying the aerosol radiative forcing in the future. [ABSTRACT FROM AUTHOR]

Marine aerosols play an important role in the Earth's climate, but their effects remain highly uncertain due to a poor understanding of their sources, properties, and atmospheric processing, partly due to limited measurements. The Coastal Fog study investigated the processes controlling the formation and properties of fog in the North Atlantic Ocean. As part of this study, aerosol-particle-size distributions and chemical composition were measured off the shore of the north-eastern United States and Atlantic Canada, and used to investigate the sources and processes affecting the observed aerosols. Processed marine air during the study was characterized by single and bimodal aerosol size distributions. Aerosols in the port city of St. John's, Newfoundland likely reflected local emissions built up due to poor ventilation, whereas aerosols observed in Halifax, Nova Scotia were likely affected by transport, cloud processing and precipitation. Finally, two particle-growth events were observed. The first event captured the appearance of 10-nm particles that grew to 30 nm over 4 h. These aerosols appeared to be newly formed in the upper portion of the boundary layer with influence from the free troposphere before subsiding to the surface. In the second event, 45-nm particles grew to 70 nm over 8 h. Our observations provide important insight into the processes affecting marine aerosols and highlight the crucial role of boundary-layer meteorology. [ABSTRACT FROM AUTHOR]

Iodine affects the radiative budget and the oxidative capacity of the atmosphere and is consequently involved in important climate feedbacks. A fraction of the iodine emitted by oceans ends up in aerosols, where complex halogen chemistry regulates the recycling of iodine to the gas-phase where it effectively destroys ozone. The iodine speciation and major ion composition of aerosol samples collected during four cruises in the East and West Pacific and Indian Oceans was studied to understand the influences on iodine’s gas-aerosol phase recycling. A significant inverse relationship exists between iodide (I–) and iodate (IO3–) proportions in both fine and coarse mode aerosols, with a relatively constant soluble organic iodine (SOI) fraction of 19.8% (median) for fine and coarse mode samples of all cruises combined. Consistent with previous work on the Atlantic Ocean, this work further provides observational support that IO3– reduction is attributed to aerosol acidity, which is associated to smaller aerosol particles and air masses that have been influenced by anthropogenic emissions. Significant correlations are found between SOI and I–, which supports hypotheses that SOI may be a source for I–. This data contributes to a growing observational dataset on aerosol iodine speciation and provides evidence for relatively constant proportions of iodine species in unpolluted marine aerosols. Future development in our understanding of iodine speciation depends on aerosol pH measurements and unravelling the complex composition of SOI in aerosols.

Study region: Ireland Study focus: Multiple studies have established that catchment geology and weathering regime strongly influence surface water chemistry, and that geochemical cycling can vary due to seasonal climatic conditions. However, fewer studies have focused on the influence these controls in a holistic manner. We relate the water chemistry of a country-wide Irish river survey to atmospheric input, underlying geology, and the influence of bogs. Climatic conditions were defined by an atypically wet winter and an unusually dry summer, providing the opportunity to investigate river chemistry variation across hydrologic conditions. Sampling included 21 of Ireland’s 22 largest rivers ranked by discharge, first-order and second-order streams draining bog lands, a second-order stream draining a limestone catchment, and downstream transects along the River Shannon. All samples were analyzed for major elements, selected trace elements, and nutrients, and a subset was analyzed for δ34SSO4. New hydrological insights: Most catchments were dominated by carbonate weathering with little contribution from the weathering of aluminosilicates. River water composition also varied geographically along the prevailing wind direction due to inputs from marine aerosols, with additional weathering components important in some systems. Seasonal influences could be seen in the chemistry of the headwaters of the River Shannon, while the lower reaches of the river exhibited less variable behavior throughout seasonal changes, likely due to the influence of lakes in the River Shannon system.

Natural aerosols in pristine regions form the baseline used to evaluate the impact of anthropogenic aerosols on climate. Sea spray aerosol (SSA) is a major component of natural aerosols. Despite its importance, the abundance of SSA is poorly constrained. It is generally accepted that wind-driven wave breaking is the principle governing SSA production. This mechanism alone, however, is insufficient to explain the variability of SSA concentration at given wind speed. The role of other parameters, such as sea surface temperature (SST), remains controversial. Here, we show that higher SST promotes SSA mass generation at a wide range of wind speed levels over the remote Pacific and Atlantic Oceans, in addition to demonstrating the wind-driven SSA production mechanism. The results are from a global scale dataset of airborne SSA measurements at 150 to 200 m above the ocean surface during the NASA Atmospheric Tomography Mission. Statistical analysis suggests that accounting for SST greatly enhances the predictability of the observed SSA concentration compared to using wind speed alone. Our results support implementing SST into SSA source functions in global models to better understand the atmospheric burdens of SSA. [ABSTRACT FROM AUTHOR]

Dimethyl sulfide (DMS), emitted from the oceans, is the most abundant biological source of sulfur to the marine atmosphere. Atmospheric DMS is oxidized to condensable products that form secondary aerosols that affect Earth's radiative balance by scattering solar radiation and serving as cloud condensation nuclei. We report the atmospheric discovery of a previously unquantified DMS oxidation product, hydroperoxymethyl thioformate (HPMTF, HOOCH2SCHO), identified through global-scale airborne observations that demonstrate it to be a major reservoir of marine sulfur. Observationally constrained model results show that more than 30% of oceanic DMS emitted to the atmosphere forms HPMTF. Coincident particle measurements suggest a strong link between HPMTF concentration and new particle formation and growth. Analyses of these observations show that HPMTF chemistry must be included in atmospheric models to improve representation of key linkages between the biogeochemistry of the ocean, marine aerosol formation and growth, and their combined effects on climate. [ABSTRACT FROM AUTHOR]

We report the first simultaneous eddy covariance flux measurements of CO2 and dimethylsulfide (DMS) over the open ocean for two North Atlantic cruises. After normalization for Schmidt number, the two gases give essentially identical gas transfer coefficients and wind speed dependences for the wind speed range 2–10 ms−1. The data indicate a linear relationship between the gas transfer coefficient and mean wind speed, with measured gas transfer coefficients slightly above the Wanninkhof (1992) parameterization, particularly at low wind speeds.

This study examines atmospheric reactive chlorine chemistry at the Cape Verde Atmospheric Observatory in the eastern tropical Atlantic. During May–June, 2007, Cl2 levels ranged from below detection (∼2 ppt) to 30 ppt. Elevated Cl2 was associated with high HNO3 (40 to 120 ppt) in polluted continental outflow transported in the marine boundary layer (MBL) to the site. Lower Cl2 was observed in recently subsided air masses with multiday free tropospheric oceanic trajectories and in air containing Saharan dust. Model simulations show that the observations of elevated Cl2 in polluted marine air are consistent with initiation of Cl chemistry by OH + HCl and subsequent heterogeneous, autocatalytic Cl cycling involving marine aerosols. Model estimates suggest that Cl atom reactions significantly impact the fates of methane and dimethylsulfide at Cape Verde and are moderately important for ozone cycling.

A flame emission aerosol sodium detector (ASD) has been developed to study the distribution of seasalt in individual marine aerosol droplets. The instrument detects sodium via D-line emission in a fuel-rich, laminar, hydrogen/oxygen/nitrogen flame. Laboratory studies with synthetic monodisperse aerosols were carried out in order to characterize the sensitivity, precision, and linearity of the technique. Experiments were also carried out with aerosols generated from mixed salt solutions and seawater in order to determine whether ionic or other matrix effects lead to interference. The ASD has a linear response function for NaCl aerosol particles from 100 nm to 2.0μm in diameter. The precision of sodium mass measurements is on the order of ±3% standard error on replicate measurements, with a quantitative response to the sodium content of a single aerosol particle that is independent of the chemical composition of the particle, i.e. anions, cations, seawater. No interferences were found with major ions in seawater and common atmospheric aerosols. These experiments demonstrate a detection limit equivalent to a 100 nm diameter dry 100% NaCl aerosol. Copyright © 2001 Elsevier Science Ltd.

The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) is an interdisciplinary investigation to improve understanding of Earth's ocean ecosystem-aerosol-cloud system. Specific overarching science objectives for NAAMES are to (1) characterize plankton ecosystem properties during primary phases of the annual cycle and their dependence on environmental forcings, (2) determine how these phases interact to recreate each year the conditions for an annual plankton bloom, and (3) resolve how remote marine aerosols and boundary layer clouds are influenced by plankton ecosystems. Four NAAMES field campaigns were conducted in the western subarctic Atlantic between November 2015 and April 2018, with each campaign targeting specific seasonal events in the annual plankton cycle. A broad diversity of measurements were collected during each campaign, including ship, aircraft, autonomous float and drifter, and satellite observations. Here, we present an overview of NAAMES science motives, experimental design, and measurements. We then briefly describe conditions and accomplishments during each of the four field campaigns and provide information on how to access NAAMES data. The intent of this manuscript is to familiarize the broad scientific community with NAAMES and to provide a common reference overview of the project for upcoming publications.

A scientific campaign was undertaken along the Western sector of the Mediterranean Sea in the summer 2015 (26th Jun to 13th Jul), with the goal of gathering information about organic contaminants affecting marine aerosol over the Italian seas and with a special focus on changes in composition due to sources. 24 PM 10 atmospheric samples in total were chemically characterized, including polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (n -alkanes) and phthalate esters. Contemporarily, regulated gaseous toxicants (i.e. ozone, nitrogen oxides and sulfur dioxide) and meteorological parameters were recorded. Samplings were carried out inshore in front of harbors (N = 7) and along the cruise, both during the vessel shipping (N = 11, transects) and at its stops offshore (N = 6). Total PAH concentrations ranged from 0.03 to 1.94 ng/m3 and raised close to harbors and coastal sites, confirming that continental sources were responsible for the strong increase of pollution levels there compared to offshore. The percent composition and diagnostic ratio rates of PAHs were different for harbors, while transects were in agreement with offshore stops, possibly due to the different impact of pollution sources. n -Alkanes (C 21 C 38) and the corresponding carbon preference index rates (CPI) were assessed; their values ranged 8.7–90 ng/m3 and 1.1–2.9 respectively, which suggested that fossil fuel combustion was the dominant source, though biogenic emission could contribute. Alkyl phthalates revealed wide variability in concentrations among aerosol samples. Moreover, long-range atmospheric transport and particle ageing effect induced by photo-oxidants were important factors controlling the composition of organic aerosols in the Mediterranean Sea air. Image 1 • PAHs, n -alkanes and gaseous contaminants were valued in the air over Mediterranean Sea. • Relevant differences were observed in the marine air among the three site types. • Vehicles exhausts seemed to be one of the principal PAH sources near harbors. • This study underlined the role of both anthropogenic and biogenic sources. • The impact of natural events like volcanic ashes was detected in the Aeolian Islands area. The patterns of PAH s, n -alkanes and phthalate esters of atmospheric samples along Western sector of Mediterranean Sea were investigated in the frame of an oceanographic campaign. [ABSTRACT FROM AUTHOR]

To understand the influences of continental emissions on marine aerosols from East Asia, the total suspended particle (TSP) samples were collected from the Yellow Sea (YS) and Bohai Sea (BS) of China through a cruise campaign during the spring of 2018. >100 individual organic compounds were identified and determined in the samples, and they were classified into 6 major groups according to the functionality and sources. The mass concentrations of total quantified organic compounds in BS (307.6 ± 268.3 ng m−3) was approximately 3 times those of YS (111.0 ± 97.3 ng m−3). Organic compounds from biomass burning (23.2 ± 34.2 ng m−3), marine/microbial source (23.1 ± 6.2 ng m−3) and fossil fuel combustion (21.4 ± 11.3 ng m−3) were the most abundant in the YS samples, whereas primary biological origins (90.0 ± 107.1 ng m−3), biomass burning (52.1 ± 39.1 ng m−3) and fossil fuel combustion (41.9 ± 20.1 ng m−3) were the most important organic species in BS marine aerosols. The concentrations of total biogenic secondary organic aerosol (BSOA) tracers including six isoprene SOA (SOA I), three monoterpene SOA (SOA M), and one β -caryophyllene SOA (SOA C) were 2.4 ± 1.5 ng m−3 and 7.3 ± 4.4 ng m−3 in the YS and BS samples, respectively. A strong correlation between BSOA tracers and levoglucosan was shown in the marine aerosol samples, indicating that biomass burning emissions could also promote BSOA formations. The spatial distribution of chemical and source characteristics suggests a relatively large impacts of continental emissions to the BS aerosols. Based on the tracer-based method, the biomass burning (YS: 4.9 ± 6.8%; BS: 8.8 ± 8.0%) was the largest contributor to OC, followed by primary biogenic OC (YS: 0.59 ± 0.44%; BS: 2.9 ± 3.0%) and biogenic secondary OC (YS: 0.45 ± 0.23%; BS: 1.0 ± 0.59%). This study suggests important contributions of biomass burning emissions to organic aerosols in the YS and BS marine atmosphere, although marine source, fossil fuel combustion and secondary formation was also substantial. [Display omitted] • Chemical and source characteristics of marine organic aerosols over the Bohai Sea and Yellow Sea were studied. • Biomass burning is a major contributor of marine organic aerosols over the Bohai Sea and Yellow Sea. • Biogenic primary emission contribution to organic carbon is higher than biogenic-derived secondary formation. • The Bohai Sea is more receptive to the input of continental emissions than the Yellow Sea. [ABSTRACT FROM AUTHOR]

Abstract The atmospheric deposition of water-soluble organic carbon (WSOC) contributes to the open ocean dissolved organic carbon (DOC) reservoir similarly to riverine discharge. However, information on the sources and composition of water-soluble organic matter (WSOM) in marine aerosols remains scarce, particularly at the molecular level. By using ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), we identified approximately ten thousand molecular formulas in marine aerosols collected over the China coastal seas and the northwestern Pacific Ocean (NWPO). Even though their molecular compositions were highly variable (Bray-Curtis distance: 0.12–0.74), four distinctive origins, namely, marine biogenic sources, secondary organic aerosols (including CHO, CHON formulas derived from biogenic volatile organic compounds (VOCs) and organosulfate derived from both biogenic and anthropogenic VOCs), soil-derived organic matter (OM) and biomass and fossil fuel burning-derived polycyclic aromatics (including highly condensed organosulfur compounds) and unsaturated compounds, were discovered. Moreover, the different types of aerosols, including aerosols from the NWPO (marine-influenced), NWPO (dust) and China coastal seas, contained various proportions of organics from different sources. The NWPO (marine-influenced) aerosols were enriched with sea spray-derived OM, which was widely distributed and was likely related to marine biological activity. The NWPO (dust) aerosols exhibited a higher fraction of soil-derived OM, while the China coastal sea aerosols exhibited a much higher fraction of organosulfate than the other aerosols. Our investigation provided detailed molecular compositional and source information for marine aerosols over the northwestern Pacific Ocean, which can be utilized to understand the composition of WSOM deposited on the sea surface. Highlights • Approximately ten thousand of molecular formulas were identified in marine aerosols. • Anthropogenic organic matter can be transported to the open ocean. • Sea spray compounds were widely observed but were enriched in the open ocean aerosols. • China coastal seas aerosols contained higher fraction of organosulfate compounds. • Dust aerosols exhibited a higher fraction of soil-derived organic matter. [ABSTRACT FROM AUTHOR]

Investigating the nature of PM 10 is crucial to differentiate sources and their relative contributions. In this study we compared the levels, and the chemical and mineralogical properties of PM 10 particles sampled in different seasons at monitoring stations representative of urban background, urban traffic and suburban traffic areas of Naples city. The aims were to relate the PM 10 load and characteristics to the location of the monitoring stations, to investigate the different sources contributing to PM 10 and to highlight PM 10 seasonal variability. Bulk analyses of chemical species in the PM 10 fraction included total carbon and nitrogen, δ 13 C and other 20 elements. Both natural and anthropogenic sources were found to contribute to the exceedances of the EU PM 10 limit values. The natural contribution was mainly related to marine aerosols and soil dust, as highlighted by X-ray diffractometry and SEM-EDS microscopy. The percentage of total carbon suggested a higher contribution of biogenic components to PM 10 in spring. However, this result was not supported by the δ 13 C values which were seasonally homogeneous and not sufficient to extract single emission sources. No significant differences, in terms of PM 10 load and chemistry, were observed between monitoring stations with different locations, suggesting a homogeneous distribution of PM 10 on the studied area in all seasons. The anthropogenic contribution to PM 10 seemed to dominate in all sites and seasons with vehicular traffic acting as a main source mostly by generation of non-exhaust emissions Our findings reinforce the need to focus more on the analysis of PM 10 in terms of quality than of load, to reconsider the criteria for the classification and the spatial distribution of the monitoring stations within urban and suburban areas, with a special attention to the background location, and to emphasize all the policies promoting sustainable mobility and reduction of both exhaust and not-exhaust traffic-related emissions. [ABSTRACT FROM AUTHOR]

Fine particles (PM 2.5 ) samples, collected at Weizhou Island over the Gulf of Tonkin on a daytime and nighttime basis in the spring of 2015, were analyzed for primary and secondary organic tracers, together with organic carbon (OC), elemental carbon (EC), and stable carbon isotopic composition (δ 13 C) of total carbon (TC). Five organic compound classes, including saccharides, lignin/resin products, fatty acids, biogenic SOA tracers and phthalic acids, were quantified by gas chromatography/mass spectrometry (GC/MS). Levoglucosan was the most abundant organic species, indicating that the sampling site was under strong influence of biomass burning. Based on the tracer-based methods, the biomass-burning-derived fraction was estimated to be the dominant contributor to aerosol OC, accounting for 15.7% ± 11.1% and 22.2% ± 17.4% of OC in daytime and nighttime samples, respectively. In two episodes E1 and E2, organic aerosols characterized by elevated concentrations of levoglucosan as well as its isomers, sugar compounds, lignin products, high molecular weight (HMW) fatty acids and β -caryophyllinic acid, were attributed to the influence of intensive biomass burning in the northern Southeast Asia (SEA). However, the discrepancies in the ratios of levoglucosan to mannosan (L/M) and OC (L/OC) as well as the δ 13 C values suggest the type of biomass burning and the sources of organic aerosols in E1 and E2 were different. Hardwood and/or C 4 plants were the major burning materials in E1, while burning of softwood and/or C 3 plants played important role in E2. Furthermore, more complex sources and enhanced secondary contribution were found to play a part in organic aerosols in E2. This study highlights the significant influence of springtime biomass burning in the northern SEA to the organic molecular compositions of marine aerosols over the Gulf of Tonkin. [ABSTRACT FROM AUTHOR]

Marine sulfate aerosols in the Southern Ocean are critical to the global radiation balance, yet the sources of sulfate and their seasonal variations are unclear. We separately sampled marine and ambient aerosols at Baring Head, New Zealand for 1 year using two collectors and evaluated the sources of sulfate in coarse (1–10 μm) and fine (0.05–1 μm) aerosols using sulfur isotopes (δ34S). In both collectors, sea‐salt sulfate (SO42−SS) mainly existed in coarse aerosols and nonsea‐salt sulfate (SO42−NSS) dominated the sulfate in fine aerosols, although some summer SO42−NSS appeared in coarse particles due to aerosol coagulation. SO42−NSS in the marine aerosols was mainly (88–100%) from marine biogenic dimethylsulfide (DMS) emission, while the SO42−NSS in the ambient aerosols was a combination of DMS (73–79%) and SO2 emissions from shipping activities (~21–27%). The seasonal variations of SO42−NSS concentrations inferred from the δ34S values in both collectors were mainly controlled by the DMS flux. [ABSTRACT FROM AUTHOR]

The traditional voltammetric method at the mercury electrode, and an acidification step developed for the determination of reduced sulfur species (RSS) in natural waters, was for the first time used for the quantification of RSS in the water-soluble fraction of fine marine aerosols collected at the Middle Adriatic location (Rogoznica Lake). The evidence of two types of non-volatile RSS that have different interaction with the Hg electrode was confirmed: mercapto-type which complexes Hg as RS−Hg and sulfide/S0-like compounds which deposits HgS. The analytical protocol that was used for RSS determination in aerosol samples is based on separate voltammetric studies of a methyl 3-mercaptopropionate (3-MPA) as a representative of mercapto-type compounds and sulfide as a representative of inorganic RSS. Our preliminary study indicates the presence of mainly RS−Hg compounds in spring samples, ranging from 2.60−15.40 ng m−3, while both, the mercapto-type (0.48−2.23 ng m−3) and sulfide and/or S0-like compounds (0.02−0.26 ng m−3) were detected in early autumn samples. More expressed and defined RS−Hg peaks recorded in the spring potentially indicate their association with biological activity in the area. Those samples were also characterized by a higher water-soluble organic carbon content and a more abundant surface-active fraction, pointing to enhanced solubility and stabilization of RSS in the aqueous atmospheric phase.

The size distribution of atmospheric aerosols together with their composition, sources and sinks, is a key element in understanding aerosol effects on the Earth's climate. Aerosol particle size distribution and chemical composition were measured over the Southern Ocean and at Antarctic region during December 2009-March 2010. Aerosol samples were collected using multi-stage low volume Air Sampler, and an aerosol size spectrometer was employed to monitor PM mass concentration continuously. The mean mass concentrations for PM, PM and PM were 1.5, 1.0 and 0.6 μg/m, respectively at the Bharati station and were almost 2.5 times higher at the Maitri station. The mass size distribution of the aerosols measured by using a low volume air sampler exhibited a bimodal feature with a peak each in the size range of 0.4 to 0.7 μm and 3 to 5 μm. The difference in concentrations between the two locations for fine particles was comparatively lower than that for simultaneously measured coarse particles. Aerosol samples were analyzed for various water-soluble ionic constituents e.g. Na, K, Ca, Mg, NH , Cl, SO and NO . Sea-salt aerosols contributed to 86% of the measured mass over the Southern Ocean, 80% over Bharati and 76% at Maitri. The Southern Ocean being the most significant source of the particles during summer time, controls the aerosols at Bharati and Maitri sites. The present study will be helpful in simulating atmospheric processes responsible for aerosol characterization over coastal Antarctica and understanding its environmental implications related to radiation budget and climate over this region. [ABSTRACT FROM AUTHOR]

We verified an algorithm using multi-wavelength Mie-Raman lidar (MMRL) observations to retrieve four aerosol components (black carbon (BC), sea salt (SS), air pollution (AP), and mineral dust (DS)) with in-situ aerosol measurements, and determined the seasonal variation of aerosol components in Fukuoka, in the western region of Japan. PM2.5, PM10, and mass concentrations of BC and SS components are derived from in-situ measurements. MMRL provides the aerosol extinction coefficient (α), particle linear depolarization ratio (δ), backscatter coefficient (β), and lidar ratio (S) at 355 and 532 nm, and the attenuated backscatter coefficient (βatt) at 1064 nm. We retrieved vertical distributions of extinction coefficients at 532 nm for four aerosol components (BC, SS, AP, and DS) using 1α532 + 1β532 + 1βatt,1064 + 1δ532 data of MMRL. The retrieved extinction coefficients of the four aerosol components at 532 nm were converted to mass concentrations using the theoretical computed conversion factor assuming the prescribed size distribution, particle shape, and refractive index for each aerosol component. MMRL and in-situ measurements confirmed that seasonal variation of aerosol optical properties was affected by internal/external mixing of various aerosol components, in addition to hygroscopic growth of water-soluble aerosols. MMRL overestimates BC mass concentration compared to in-situ observation using the pure BC model. This overestimation was reduced drastically by introducing the internal mixture model of BC and water-soluble substances (Core-Gray Shell (CGS) model). This result suggests that considering the internal mixture of BC and water-soluble substances is essential for evaluating BC mass concentration in this area. Systematic overestimation of BC mass concentration was found during summer, even when we applied the CGS model. The observational facts based on in-situ and MMRL measurements suggested that misclassification of AP as CGS particles was due to underestimation of relative humidity (RH) by the numerical model in lidar analysis, as well as mismatching of the optical models of AP and CGS assumed in the retrieval with aerosol properties in the actual atmosphere. The time variation of lidar-derived SS was generally consistent with in-situ measurement; however, we found some overestimation of SS during dust events. The cause of this SS overestimation is mainly due to misclassifying internally mixing DS as SS, implying that to consider internal mixing between DS and water-soluble substances leads to better estimation. The time-variations of PM2.5 and PM10 generally showed good agreement with in-situ measurement although lidar-derived PM2.5 and PM10 overestimated in dust events.

Oceans dominate emissions of dimethyl sulfide (DMS), the major natural sulfur source. DMS is important for the formation of non-sea salt sulfate (nss-SO4 2-) aerosols and secondary particulate matter over oceans and thus, significantly influence global climate. The mechanism of DMS oxidation has accordingly been investigated in several different model studies in the past. However, these studies had restricted oxidation mechanisms that mostly underrepresented important aqueous-phase chemical processes. These neglected but highly effective processes strongly impact direct product yields of DMS oxidation, thereby affecting the climatic influence of aerosols. To address these shortfalls, an extensive multiphase DMS chemistry mechanism, the Chemical Aqueous Phase Radical Mechanism DMS Module 1.0, was developed and used in detailed model investigations of multiphase DMS chemistry in the marine boundary layer. The performed model studies confirmed the importance of aqueousphase chemistry for the fate of DMS and its oxidation products. Aqueous-phase processes significantly reduce the yield of sulfur dioxide and increase that of methyl sulfonic acid (MSA),which is needed to close the gap between modeled and measured MSA concentrations. Finally, the simulations imply that multiphase DMS oxidation produces equal amounts of MSA and sulfate, a result that has significant implications for nss-SO4 2- aerosol formation, cloud condensation nuclei concentration, and cloud albedo over oceans. Our findings show the deficiencies of parameterizations currently used in higher-scale models, which only treat gas-phase chemistry. Overall, this study shows that treatment of DMS chemistry in both gas and aqueous phases is essential to improve the accuracy of model predictions. [ABSTRACT FROM AUTHOR]

The effect of highly concentrated salt solutions of marine-relevant cations (Na + , K + , Mg 2+ , and Ca 2+ ) on Langmuir monolayers of dipalmitoylphosphatidylcholine (DPPC) was investigated by means of surface pressure-area isotherms, Brewster angle microscopy (BAM), and infrared reflection-absorption spectroscopy (IRRAS). It was found that monovalent cations and Mg 2+ have similar phase behavior, causing DPPC monolayers to expand, while Ca 2+ induces condensation. All cations disrupted the surface morphology at high cation concentration, resulting in decreased reflectivity from the monolayer. Monolayer refractive index was calculated from BAM image intensity in the liquid condensed phase and decreased with increasing cation concentration, which suggests that orientation of the alkyl chains change. Monovalent ions increase ordering of the alkyl chains, more than divalents, yet have little interaction with the DPPC headgroup. Mg 2+ induces gauche defects in the alkyl chain and increases headgroup hydration at low lipid coverage but increases chain ordering and dehydrates the headgroup at high lipid coverage. Ca 2+ orders alkyl chains and dehydrates the phosphate moiety, independent of lipid phase. At the highest salt concentration investigated, significant narrowing of the asymmetric PO 2 − vibrational mode occurs and is attributed to considerable dehydration of the DPPC headgroup. [ABSTRACT FROM AUTHOR]

In order to evaluate environmental controls on the soiling formation and decay of building stones a set of mapping and physical and chemical analyses were carried out on granite from a historical church in the polluted centre of Rio de Janeiro. These techniques highlight the increasing of threatening damage on generally perceived as a durable building material, caused by granular disaggregation and contour scaling in areas close to ground level. Mapping also indicated the formation of black crusts over entire building façades, concentrated on areas sheltered from rain-wash. Analyses demonstrated the influence of marine aerosols, rock and mortar composition and mostly of the atmospheric pollutants on the decay and soiling of the granite. Much of the decay is associated specifically with the presence of halite (NaCl) and gypsum (CaS04.2H2O). The fact that black, gypsum crusts are able to develop over entire façades in a humid subtropical environment is testimony to the high levels of local pollution, especially particulate deposition. Reduced rainwash, in sheltered micro-environments of narrow, canyon-like streets, overcomes the gypsum tendency to bewashed away from buildings façades. These observations further highlight that decay processes are primarily controlled by microclimatic conditions.Com o objetivo de se avaliar os controles ambientais na formação de crostas e deterioração de rochas ornamentais em fachadas de prédios históricos, uma série de mapeamentos e análises fisicas e químicas foram realizados em granitos da fachada de uma igreja histórica numa área poluída no centro da cidade do Rio de Janeiro. Estas técnicas destacam a ameaça crescente dos danos causados pela desagregação granular e esfoliação da rocha que é fortemente percebido por se tratar de um material de alta durabilidade usado na fachada do prédio em áreaslocalizadas ao nível do chão. O exercício de mapeamento possibilitou a demarcação e observação das áreas afetadas pela formação de crosta negra sobre toda a fachada do prédio, principalmente concentradas em áreas abrigadas da ação da chuva. As análises demonstraram a influência de aerosóis marinhos, composição das rochas e argamassas e dos poluentes atmosféricos na deterioração e formação de crostas no granito. Muito da deterioração é associado especificamente a presença de sais, tais como halita (NaCl) e gipsita (CaS0(4).2H2O). O fato da crosta negra de gipsita ser capaz de se desenvolver sobre toda a fachada do prédio, em um ambiente sub-tropical úmido é testemunha da eficácia dos altos níveis de poluição local, especialmente da deposição de particulados, e da reduzida lavagem pela chuva em um micro-ambiente protegido,em ruas estreitas, que funcionam como corredores de poluição, impedindo a tendência da gipsita ser lavada das fachadas dos prédios históricos. Essa observação destaca que os processos de intemperismo operante, são principalmente controlados por condições microclimáticas.

Organic aerosols (OA) are universally regarded as an important component of the atmosphere that have far-ranging impacts on climate forcing and human health. Many of these impacts are related to OA molecular characteristics. Despite the acknowledged importance, current uncertainties related to the source apportionment of molecular properties and environmental impacts make it difficult to confidently predict the net impacts of OA. Here we evaluate the specific molecular compounds as well as bulk structural properties of total suspended particulates in ambient OA collected from key emission sources (marine, biomass burning, and urban) using ultrahigh resolution mass spectrometry (UHR-MS) and proton nuclear magnetic resonance spectroscopy (¹H NMR). UHR-MS and ¹H NMR show that OA within each source is structurally diverse, and the molecular characteristics are described in detail. Principal component analysis (PCA) revealed that (1) aromatic nitrogen species are distinguishing components for these biomass burning aerosols; (2) these urban aerosols are distinguished by having formulas with high O/C ratios and lesser aromatic and condensed aromatic formulas; and (3) these marine aerosols are distinguished by lipid-like compounds of likely marine biological origin. This study provides a unique qualitative approach for enhancing the chemical characterization of OA necessary for molecular source apportionment. [ABSTRACT FROM AUTHOR]

Humic-like substances (HULIS) are organic macromolecular compounds (water-soluble brown carbon) that have an important effect on climate change due to their strong light absorption. However, the molecular composition of HULIS in atmospheric particles in the offshore Eastern China Sea (OECS) has scarcely been investigated. In this study, solid-phase extraction (SPE) was performed to collect HULIS from water extracts. The molecular compositions of samples were characterized by negative-ion electrospray ionization (ESI) Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). A total of 1197–1828 molecular formulas of HULIS were identified in collected samples, and three of them with higher intensities near Shanghai city, Zhejiang province, and Fujian province were discussed in detail. The identified molecular formulas were classified into four major subgroups, including CHO, CHNO, CHOS, and CHNOS compounds. S-containing formulas (CHOS and CHNOS) represented the dominant components (21.0–76.7% relative abundance), followed by CHO (16.5–64.3%), while CHNO compounds constituted 6.1–18.1% of the identified formulas. High fractions of CHO formulas were found in the list of α-pinene ozonolysis yields and S-containing formulas with olefinic structures were abundant in atmospheric particles, suggesting enhanced SOA formation. The samples had a relative abundance-weighted average O/C of 0.25–0.67 and a double bond equivalent of 3.49–4.96. Most identified formulas (>89%) were assigned to aliphatic and olefinic species. The CHNO and S-containing formulas identified in the samples were primarily contributed by –ONO 2 functional groups and organosulfates. Biogenic volatile organic compounds (α-pinene or monoterpene) were the dominant precursors of HULIS in the samples. Lignin-like species (41–46%) and protein/amino sugars (28–30%) were the major species among substance classes. The results provide an improved understanding of the molecular composition of HULIS in the Eastern China Sea. • The molecular composition of humic-like substances (HULIS) was investigated in OECS. • Most identified compounds were assigned to aliphatic and olefinic species. • HULIS in marine aerosols were mainly derived from biogenic sources rather than anthropogenic sources. [ABSTRACT FROM AUTHOR]

To better understand the long-range atmospheric transport of microbial aerosols from Asia to the western North Pacific, marine aerosols were collected from Chichijima Island (27°04′N; 142°13′E) on a biweekly basis during 1990–1993. These samples were investigated for β– and ω–hydroxy fatty acids (FAs) as terrestrial biomarkers of Gram-negative bacteria (GNB) and higher plants, respectively. The average concentrations of β–hydroxy (C 8 –C 31 ) and ω–hydroxy (C 11 –C 28 ) FAs show pronounced seasonal variability with maxima in spring (300 ± 70 pg m −3 ) and winter (650 ± 330 pg m −3 ), respectively. Airmass back trajectories clearly indicate the continental outflow from Asia during winter to spring, whereas maritime airmasses dominate in summer to autumn over Chichijima. It is noteworthy that atmospheric abundances of β–hydroxy FAs and, thus, the estimated mass concentration of GNB have not been significantly varied between polluted (continental) and pristine (oceanic) airmasses during the study period. However, the relative source strength observed from cluster analysis of β–hydroxy FAs in the polluted continental airmassess vary significantly among seasons (winter: 98%, spring: 63%, summer; 11%, autumn: 26%). In addition, there were distinguishable differences between polluted continental and pristine maritime airmasses with regard to C-number predominance. The even C-number predominance of β– and ω–hydroxy FAs (∼80 and 98% of total mass concentration, respectively) in marine aerosols could be due to their significant contribution from GNB, terrestrial plants and soil microorganisms. These results have implications towards assessing the atmospheric transport of bacterial and plant lipids in the continental outflow over the open ocean. [ABSTRACT FROM AUTHOR]

Nutrient inputs and dynamics of the fynbos ecosystem, particularly after a fire, are poorly understood. This article provides chemical analyses of macronutrients (Cl, Na, SO 4 , Mg, Ca and K) in rainwater, stream water, soil and bedrock over a period of one year following a fire event in a coastal mountain sandstone fynbos ecosystem. Rainwater, stream water, soil and bedrock samples were taken from a mountain fynbos area underlain by homogeneous Peninsula Formation sandstone bedrock for a one-year period. Rainwater, stream water and soil saturated paste extracts were analysed for macronutrients using a Dionex DX-120 Ion Chromatograph. Crushed soil and bedrock samples were analysed for major element oxide and S content. Above-ground biomass recovery after one year was modest (5–10% of the 19-year-old pre-fire biomass) with marine aerosols supplying Cl and Na ions to the ecosystem and a significant amount of Mg, SO 4 , Ca and K. Additional Mg, SO 4 , Ca and K are supplied by deposition of local and regional fire ash and dust (mineral aerosols) transported from inland sources mostly by northwesterly winter winds. Nutrient loss diminishes rapidly with the return of pre-fire stream values within 9 months after fire, with nutrients gradually replaced through atmospheric deposition rather than the slow weathering bedrock. Macronutrients supplied to the study area reflect seasonal differences with atmospheric processes being the primary source of nutrients to the ecosystem. [ABSTRACT FROM AUTHOR]

In this study, Hg isotopes, backward trajectory, and emission inventory were utilized to explore the effects of possible emission sources and photochemical pathways on fine-particle bound mercury during two single haze events in February 2017 and January 2018 at Gucheng (38.31°N, 115.25°E). Results showed that (a) the large variations of odd-mass mass-independent fractionation values in fine-particle bound mercury showed the joint contributions of different source regions during haze evolution; (b) biomass burning significantly contributed to fine-particle bound mercury during winter haze in northern China; (c) fine-particle bound mercury during haze evolution at Gucheng (an inland site in China) was impacted by marine aerosols; (d) photoreduction had a significant impact on fine-particle bound mercury during haze evolution and a relatively more intense solar radiation may be conducive to photoreduction during haze. These findings provide a theoretical basis for developing methods and strategies to control fine-particle bound mercury pollution. • Biomass burning significantly contributed to PM 2.5 -Hg during winter haze in northern China. • PM 2.5 -Hg during haze evolution in Gucheng was impacted by marine aerosols. • Photoreduction had an important impact on PM 2.5 -Hg during haze evolution. • A relatively more intense solar radiation may be conducive to photoreduction during haze. [ABSTRACT FROM AUTHOR]

Atmospheric concentrations of non-sea-salt sulfate (nss-SO 4 2− ) and methanesulfonic acid (MSA) were measured over the Pacific Ocean between 48°N and 55°S during the KH-08-2 and MR08-06 cruises in summers of 2008 and 2009, in order to investigate spatial distributions of each species and MSA/nss-SO 4 2− ratio. In the subarctic western North Pacific, mean concentrations of nss-SO 4 2− and MSA in bulk (fine + coarse) aerosols were 1.1 μg m −3 and 0.061 μg m −3 , whereas those in the South Pacific were 0.25 μg m −3 and 0.043 μg m −3 , respectively. In the subtropical western North Pacific, it was observed that nss-SO 4 2− concentration sharply increased from 0.45 μg m −3 up to 4.2 μg m −3 under the dominant influence of the Kilauea volcano, while that of MSA remained low. Mean MSA/nss-SO 4 2− ratio observed in the South Pacific was approximately 3.7 times higher than that in the subarctic western North Pacific, although the mean MSA concentration in the subarctic western North Pacific was a factor of 1.4 higher than that in the South Pacific. The distributions of nss-SO 4 2− , MSA, and MSA/nss-SO 4 2− ratio suggested that aerosol nss-SO 4 2− plays a key role in the latitudinal variation in MSA/nss-SO 4 2− ratio over the North and South Pacific during summer periods, and that high MSA concentrations in the subarctic western North Pacific and the South Pacific were related to high biological productivity and low air temperature. During the cruises, an inverse relationship ( r = −0.72, p < 0.01) was observed between satellite-derived chlorophyll a concentration and air temperature, showing that high biological productivity occurred at high latitudes, where air temperature were relatively low, in both hemispheres during the summer periods. Although both MSA concentration and MSA/nss-SO 4 2− ratio showed inverse and positive relationships with air temperature and chlorophyll a concentration, respectively, the correlations between these variables were weak, suggesting that the distributions of MSA concentration and MSA/nss-SO 4 2− ratio over the North and South Pacific during the summer periods were influenced by more complex factors. Estimates using the MSA/nss-SO 4 2− ratios measured in different latitude regions in the Pacific Ocean indicated that the contributions from biogenic sources accounted for 9.6–58% of the total nss-SO 4 2− in aerosols collected in the subarctic western North Pacific, 15–85% in the subtropical western North Pacific, 10–70% in the central North Pacific, and 12–97% in the South Pacific, showing strong influence of anthropogenic nss-SO 4 2− in the subarctic western North Pacific despite the higher mean concentration of MSA in the subarctic western North Pacific than in the South Pacific. [ABSTRACT FROM AUTHOR]

Particulates and/or aerosols are harmful pollutants to cladding rocks. They are a mixture of very small particles dispersed in the atmosphere in the form of liquid or solid and may be product from the nebulization of liquid or solid substances or condensation from the gaseous phase (burning fossil fuels, etc). Fluxes of heat and vapor between the atmosphere and the rock favor or impede the deposit on the surface of particles and gases, they enter the interior of rocks, which facilitate migration of salts, formation of efflorescence, microfractures, loss of gloss, stains and development of organisms. The preservation of brightness and susceptibility to weathering of the marbles Bege Bahia depend on the mineralogical composition. The calcite is the dominant mineral: the vulnerability manifests in the physical domain, due to the low hardness (3) and in the chemical, where the reactivity with acid products (including rain itself) results in loss of reflectance and dissolution. Daily changes in relative humidity, in Recife, around 80%, favor the crystallization and dissolution of salts, being ideal conditions for change processes in claddings such as stains lithic detachments, efflorescence and disaggregation. Marbles, mainly sedimentary limestones, present early changeability and arenization, sometimes, under 5 years of application, if not resined. [ABSTRACT FROM AUTHOR]

This paper uses artificial neural networks (ANN), combined with k-means clustering, to understand the complex time series of PM10 and PM2.5 concentrations at a coastal location of New Zealand based on data from a single site. Out of available meteorological parameters from the network (wind speed, wind direction, solar radiation, temperature, relative humidity), key factors governing the pattern of the time series concentrations were identified through input sensitivity analysis performed on the trained neural network model. The transport pathways of particulate matter under these key meteorological parameters were further analysed through bivariate concentration polar plots and k-means clustering techniques. The analysis shows that the external sources such as marine aerosols and local sources such as traffic and biomass burning contribute equally to the particulate matter concentrations at the study site. These results are in agreement with the results of receptor modelling by the Auckland Council based on Positive Matrix Factorization (PMF). Our findings also show that contrasting concentration-wind speed relationships exist between marine aerosols and local traffic sources resulting in very noisy and seemingly large random PM10 concentrations. The inclusion of cluster rankings as an input parameter to the ANN model showed a statistically significant (p < 0.005) improvement in the performance of the ANN time series model and also showed better performance in picking up high concentrations. For the presented case study, the correlation coefficient between observed and predicted concentrations improved from 0.77 to 0.79 for PM2.5 and from 0.63 to 0.69 for PM10 and reduced the root mean squared error (RMSE) from 5.00 to 4.74 for PM2.5 and from 6.77 to 6.34 for PM10. The techniques presented here enable the user to obtain an understanding of potential sources and their transport characteristics prior to the implementation of costly chemical analysis techniques or advanced air dispersion models. [ABSTRACT FROM AUTHOR]

Abstract: The number concentrations of bacteria, viruses, and insoluble submicrometer particles in seawater were simultaneously measured to investigate the effects of biological activity and anthropogenic sources on the number of submicrometer particles in seawater sampled at various coastal locations during different seasons and at varying tidal levels. It was found that when an anthropogenic source was located near a sampling site, there was an increase in the number concentration of insoluble submicrometer particles, as well as enhancements of anthropogenic elements. The concentration of insoluble submicrometer particles was the highest at the Taean site, which had the strongest biological activity. The particle concentration was two to three times higher in spring than in summer or winter, which aligns with the observation that spring had the highest biological activity, which may be caused by the increase in solar radiation and nutrients. During spring tide, when there is maximum tidal variation, strong mixing and the suspension of accumulated sediments can occur. At this time, there were significant increases in the number concentrations of insoluble particles and viruses in seawater. Data suggest that the location, season, and tidal level have great impacts on the biological materials in seawater, which affects the number of insoluble submicrometer particles, and contributes to primary marine aerosols produced by the bubble bursting process. [Copyright &y& Elsevier]