Fresh Sea Salt Research Articles

Source apportionment of fine carbonaceous particles by positive matrix factorization at Gosan background site in East Asia

Fine particle (aerodynamic diameter < 2.5 µm) samples were collected during six intensive measurement periods from November 2001 to August 2003 at Gosan, Jeju Island, Korea, which is one of the representative background sites in East Asia. Chemical composition of these aerosol samples including major ion components, trace elements, organic and elemental carbon (OC and EC), and particulate polycyclic aromatic hydrocarbons (PAHs) were analyzed to study the impact of long-range transport of anthropogenic aerosol. Aerosol chemical composition data were then analyzed using the positive matrix factorization (PMF) technique in order to identify the possible sources and estimate their contribution to particulate matter mass. Fourteen sources were then resolved including soil dust, fresh sea salt, transformed natural source, ammonium sulfate, ammonium nitrate, secondary organic carbon, diesel vehicle, gasoline vehicle, fuel oil combustion, biomass burning, coal combustion, municipal incineration, metallurgical emission source, and volcanic emission. The PMF analysis results of source contributions showed that the natural sources including soil dust, fresh and aged sea salt, and volcanic emission contributed to about 20% of the measured PM 2.5 mass. Other primary anthropogenic sources such as diesel and gasoline vehicle, coal and fuel oil combustion, biomass burning, municipal incineration, metallurgical source contributed about 34% of PM 2.5 mass. Especially, the secondary aerosol mainly involved with sulfate, nitrate, ammonium, and organic carbon contributed to about 39% of the PM 2.5 mass.

Chemical markers for sea salt in IMPROVE aerosol data

The Interagency Monitoring of PROtected Visual Environments (IMPROVE) network monitors chemically speciated fine-particle concentrations at about 170 rural or remote sites in the United States, including several in coastal settings. Sea salt is a major component of marine aerosols, and can have significant optical effects on both global and local scales. Sodium is the most commonly employed chemical marker for sea salt, but the ion is not a target of IMPROVE's routine chromatography and the element is poorly detected by IMPROVE's routine X-ray fluorescence analysis. This paper examines data from six coastal sites where sea salt is abundant, to identify more reliable signatures of fresh sea salt in routine IMPROVE data. The chloride ion measurement, by ion chromatography on a Nylon filter sampling behind a carbonate denuder, appears to represent the total concentration of this reactive species at the selected sites. It is shown to be a good predictor of conserved sea salt markers such as non-crustal strontium, calcium and potassium, as well as the portion of gravimetric mass not explained by terrestrial fractions. These conclusions may not extend to other locations where sea salt is a smaller and more aged fraction of the aerosol mix.

Estimation of source apportionment and potential source locations of PM 2.5 at a west coastal IMPROVE site

Particle composition data for PM 2.5 samples collected at Kalmiopsis Interagency Monitoring of Protected Visual Environments (IMPROVE) site in southwestern Oregon from March 2000 to May 2004 were analyzed to provide source identification and apportionment. A total of 493 samples were collected and 32 species were analyzed by particle induced X-ray emission, proton elastic scattering analysis, photon-induced X-ray fluorescence, ion chromatography, and thermal optical reflectance methods. Positive matrix factorization (PMF) was used to estimate the source profiles and their mass contributions. The PMF modeling identified nine sources. In the Kalmiopsis site, the average mass was apportioned to wood/field burning (38.4%), secondary sulfate (26.9%), airborne soil including Asian dust (8.6 %), secondary nitrate (7.6%), fresh sea salt (5.8%), OP-rich sulfate (4.9%), aged sea salt (4.5 %), gasoline vehicle (1.9%), and diesel emission (1.4%). The potential source contribution function (PSCF) was then used to help identify likely locations of the regional sources of pollution. The PSCF map for wood/field burning indicates there is a major potential source area in the Siskiyou County and eastern Oregon. The potential source locations for secondary sulfate are found in western Washington, northwestern Oregon, and the near shore Pacific Ocean where there are extensive shipping lanes. It was not possible to extract a profile directly attributable to ship emissions, but indications of their influence are seen in the secondary sulfate and aged sea salt compositions.

Comparison of Source Apportionments of Fine Particulate Matter at Two San Jose Speciation Trends Network Sites

In this study, the chemical composition of fine particulate matter samples collected at U.S. Environmental Protection Agency Speciation Trends Network sites in San Jose, CA, from February 2000 to February 2005 were analyzed. A San Jose site was initially established at 4th Street and then subsequently moved to Jackson Street in mid-2002. These sites are approximately 1 km apart. There were no known major changes in the nature of the sources in the area over this period. The study used positive matrix factorization model to extract the source profiles and their mass contributions and to compare the results for the congruence of the source apportionments between these two nearby sites. In the case of the 4th Street site, the average mass was apportioned to wood combustion (32.1 +/- 2.5%), secondary nitrate (22.3 +/- 2%), secondary sulfate (10.7 +/- 0.6%), fresh sea salt (7.7 +/- 0.9%), gasoline vehicles (7.3 +/- 0.5%), aged sea salt (6.8 +/- 0.4%), road dust (6.7 +/- 0.7%), diesel emissions (3.9 +/- 0.3%), and a Ni-related industrial source (2.5 +/- 0.4%). At the Jackson Street site, the average mass was apportioned to wood combustion (33.6 +/- 2.6%), secondary nitrate (20.3 +/- 1.9%), secondary sulfate (13.9 +/- 0.9%), aged sea salt (12.4 +/- 0.7%), gasoline vehicle (8.3 +/- 0.6%), fresh sea salt (5.3 +/- 0.5%), diesel emission (3.2 +/- 0.3%), road dust (1.9 +/- 0.1%), and Ni-related industrial source (1.3 +/- 0.1%). Conditional probability function analysis was used to help identify local sources. These results suggested that moving the sampling site a short distance had little effect on the nature of the resolved source types although some differences in their quantitative impacts were obtained in the positive matrix factorization analyses.

Importance of the surface reaction OH + Cl&amp;lt;sup&amp;gt;−&amp;lt;/sup&amp;gt; on sea salt aerosol for the chemistry of the marine boundary layer – a model study

Abstract. The reaction of the hydroxyl radical with chloride on the surface of sea salt aerosol producing gas phase Cl2 and particulate OH− and its implications for the chemistry of the marine boundary layer under coastal, remote, and very remote conditions have been investigated with a numerical model. This reaction had been suggested by Laskin et al. (2003) to play a major role in the sulfur cycle in the marine boundary layer by increasing the sulfate production in sea salt by O3 oxidation due to the additional production of alkalinity in the particle. Based on literature data a new "best estimate" for the rate coefficient of the reaction was deduced and applied, showing that the additional initial sulfate production by this reaction is less than 1%, therefore having only a minor impact on sulfate production. Even though the gas phase concentration of Cl2 increased strongly in the model, the concentration of Cl radicals increased by less than 5% for the "best guess" case. Additional feedbacks between the cycles of chlorine and sulfur in the marine boundary layer are discussed as well as a two-stage acidification of large fresh sea salt aerosol.

Continental impact on marine boundary layer coarse particles over the Atlantic Ocean between Europe and Antarctica

Aerosol samples were collected in the Atlantic marine boundary layer between the English Channel and Antarctica during November–December 1999. The composition of coarse (aerodynamic diameter ∼1–3 μm) individual aerosol particles was studied using the SEM/EDX method. The major particle types observed were fresh sea salt, sea-salt particles reacted partly or totally with sulphuric acid or nitric acid, Mg-sulphate, Ca-sulphate, mixed aluminosilicates and sea salt, aluminosilicates, Ca-rich particles and Fe-rich particles. The relative fractions of sea-salt particles with moderate or strong Cl depletion were high near the coasts of Europe (65–74%) and Northern Africa (44–87%), low far from the coast of Western Africa (10–20%) and very low in remote sea areas between Africa and Antarctica (∼1%). The Cl depletion was strongest when air masses arrived from the direction of anthropogenic pollution sources. The fractions of Mg-sulphate particles were high (18–25%) in 2 samples near Europe. The Mg-sulphate particles were probably formed as a result of fractional recrystallization of sea-salt particles in which Cl was substituted by sulphate. It remained unclear whether these particles were formed in the atmosphere or during and after sampling. The relative fractions of particles from continental sources were quite low (10–15%) near Europe, very high (25–78%) near the coast of Northwestern Africa and very low in the remote sea areas (0–2%). Most of the continental particles were aluminosilicates and some of them were internally mixed with sea salt. Near the coast of Northwestern Africa, the main source of aluminosilicates was Saharan dust, and near the Gulf of Guinea, emissions from biomass burning were also mixed with aluminosilicates and sea salt.

Model study of multiphase DMS oxidation with a focus on halogens

Abstract. We studied the oxidation of dimethylsulfide (DMS) in the marine boundary layer (MBL) with a one-dimensional numerical model and focused on the influence of halogens. Our model runs show that there is still significant uncertainty about the end products of the DMS addition pathway, which is especially caused by uncertainty in the product yield of the reaction of the intermediate product methyl sulfinic acid (MSIA) with OH. BrO strongly increases the importance of the addition branch in the oxidation of DMS even when present at mixing ratios smaller than 0.5pmol mol-1. The inclusion of halogen chemistry leads to higher DMS oxidation rates and smaller DMS to SO2 conversion efficiencies. The DMS to SO2 conversion efficiency is also drastically reduced under cloudy conditions. In cloud-free model runs between 5 and 15% of the oxidized DMS reacts further to particulate sulfur, in cloudy runs this fraction is almost 100%. Sulfate production by HOClaq and HOBraq is important in cloud droplets even for small Br- deficits and related small gas phase halogen concentrations. In general, more particulate sulfur is formed when halogen chemistry is included. A possible enrichment of HCO3- in fresh sea salt aerosol would increase pH values enough to make the reaction of S(IV)* (=SO2,aq+HSO3-+SO32-) with O3 dominant for sulfate production. It leads to a shift from methyl sulfonic acid (MSA) to non-sea salt sulfate (nss-SO42-) production but increases the total nss-SO42- only somewhat because almost all available sulfur is already oxidized to particulate sulfur in the base scenario. We discuss how realistic this is for the MBL. We found the reaction MSAaq+OH to contribute about 10% to the production of nss-SO42- in clouds. It is unimportant for cloud-free model runs. Overall we find that the presence of halogens leads to processes that decrease the albedo of stratiform clouds in the MBL.

Active chlorine release from marine aerosols: Roles for reactive iodine and nitrogen species

Recent laboratory measurements of the uptake of gaseous hypoiodous acid (HOI) on NaCl, NaBr, and sea‐salt surfaces have been used to aid calculation of the expected liberation of chlorine atoms from sea‐salt aerosol resulting from marine boundary layer (MBL) iodine chemistry. An existing model has been extended to include reactive chlorine chemistry resulting from two activation mechanisms. Measurements of the iodine monoxide (IO) and nitrate (NO3) radicals from three recent field experiments have been used to constrain numerical simulations, investigating the relative importance of the iodine‐and nitrogen‐mediated mechanisms. These calculations show that the reactive uptake of both HOI and N2O5 in the MBL can liberate Cl atoms from sea‐salt aerosol at a significant rate. A characteristic pulse of Cl production leading to several thousand molecules per cubic centimeter after sunrise may prove to be a useful diagnostic for the iodine‐mediated mechanism. Steady daytime production is predicted, leading to steady state [Cl] of several hundred to a few thousand molecules per cubic centimeter, perhaps over wide areas of the oceans. In addition, under certain conditions reactive bromine chemistry due to IBr release from fresh sea salt by reaction of HOI may dominate ICl production.

Aerosol penetration in bulk filter samples of coastal maritime aerosols

Aerosol composition was monitored at two coastal locations in Australia. One was in a temperature environment at Victor Harbor, South Australia where in the period 1978–1979 55 samples were collected. The second site was in a tropical environment at Cowley Beach, North Queensland with 90 samples collected at this site from 1980 to 1981. The quantitative atomic compositions of the soluble inorganic fraction of these aerosols were determined using indirect analyses of high volume filter samples employing the X-ray fluorescence technique (XRF), where all elements with atomic number greater than 10 could be analyzed. Evidence is presented of a sampling artifact where the depth distribution through the sampling filter paper for the maritime aerosol takes on a U-shape which may arise from the process of fractionation of the fresh sea salt nuclei. Such distribution could not be attributed to sampling in high humidities as they did not generally apply. Direct XRF analysis of the aerosol sample in the filter paper was also undertaken to provide a semi-quantitative estimate of the insoluble aerosol component concentration.

Significance of fresh water molluscs for correlation of continental and marine Pleistocene of Ponto Caspian

Correlation of continental and marine deposits of Ponto Caspian is based by the author on the joint findings or on the interlaid deposits of fresh water and sea (salt water) molluscs. These locations were observed in the sediments of limans, deltas and fresh water parts of the sea at river mouths as well as in the sediments of bays and straits of the northern part of the Ponto Caspian Basin. They were studied in the liman, deltaic and sublitoral deposits of the Danube Bay, the northeastern and southern coasts of the Sea of Azov, the Kerch and Manich straits and the northern Pricaspian. Paleogeographical conditions in these regions favoured the migration of fresh water molluscs and stipulated the identity of their composition and evolution in the river systems of the south and southeastern part of the Russian Plain.