Μm In Summer Research Articles

Associations between Indoor and Outdoor Size-Resolved Particulate Matter in Urban Beijing: Chemical Compositions, Sources, and Health Risks

Ventilation may lead to a deterioration in indoor air quality in urban environments located close to roads. Understanding the differences in the chemical compositions of size-resolved particulate matter (PM) in indoor air and outdoor air could aid in assessing the health impacts of air in these settings and establishing relevant regulation policies. In this study, indoor and outdoor size-resolved PM was collected from an office in Beijing in summer (between 5 and 25 July 2020) and winter (between 5 and 31 January 2021). Its chemical components, including sulfate, nitrate, ammonium, chlorine, organic matter (OM), elemental carbon (EC), crustal materials (CM), and heavy metals (HM), were analyzed. The mean levels of indoor and outdoor PM2.1 and PM9 were found to be much higher than those in the guidelines for PM2.5 and PM10 outlined by the National Ambient Air Quality Standard. Moreover, the levels of PM2.1 and PM2.1–9 mass were higher outdoors than they were indoors. The size distributions of mass concentrations were shown to be bimodal, peaking at 0.43–0.65 μm and 4.7–5.8 μm, respectively. The most abundant chemicals were OM, nitrate, and sulfate for PM2.1 and OM, CM, and nitrate for PM2.1–9. We found higher percentages of sulfate, nitrate, ammonium, EC, and HM in smaller-size fractions of PM. Additionally, positive matrix factorization showed that biomass burning, secondary inorganic aerosol, coal combustion, dust, traffic, and industrial pollution were the main sources of PM during the study period. The greatest non-carcinogenic and carcinogenic hazards were found at 0.43–0.65 μm in summer and 2.1–3.3 μm in winter. Our results indicate that size-resolved PM of ambient origin may infiltrate buildings near roads to varying degrees, resulting in negative health effects.

Spatial and temporal variability of dissolved methane concentrations and diffusive emissions in the Three Gorges Reservoir

Methane (CH4) emissions from freshwater aquatic systems such as rivers and reservoirs are an important component of the global methane budget. However, the estimation can be largely affected by the spatial and temporal resolutions of measurements. Especially, the lack of high-resolution studies in the Three Gorges Reservoir (TGR), one of the largest reservoirs in the world, has led to a longstanding debate on its CH4 emissions. In this study, the spatial distribution and seasonal variations of dissolved CH4 concentrations were measured using a fast-response automated gas equilibrator in the TGR. We observed large spatiotemporal variations of dissolved CH4 (mean ± SD: 0.26 ± 0.19 μM in summer and 0.24 ± 0.17 μM in winter). Higher concentrations with stronger variations were found in the upstream than in the section close to the Three Gorges Dam. The dissolved CH4 concentration in the TGR was mainly influenced by sewage discharge, sedimentation, topographical conditions, tributaries, and spatial and seasonal variations in hydrodynamics. Regression analyses suggest that the concentration can be characterized by sewage discharge, water depth, and electrical conductivity to a certain extent. Mean diffusive CH4 fluxes from the TGR in summer and winter were 16.2 mg m−2 d−1 and 3.1 mg m−2 d−1, respectively. Downsampling simulations show that scaling dissolved CH4 in the TGR from one site likely involves large errors, and at least ∼38 sites and ∼52–58 sites are needed to achieve an accurate estimate in summer and winter, respectively. Due to the large spatial and temporal heterogeneity, high-resolution measurements are key to improving the reliability of CH4 estimates and assessing the contribution of the TGR to regional and global CH4 budgets.

Size distributions and dry deposition fluxes of water-soluble inorganic nitrogen in atmospheric aerosols in Xiamen Bay, China.

Size-segregated aerosol particles were collected using a high volume MOUDI sampler at a coastal urban site in Xiamen Bay, China, from March 2018 to June 2020 to examine the seasonal characteristics of aerosol and water-soluble inorganic ions (WSIIs) and the dry deposition of nitrogen species. During the study period, the annual average concentrations of PM1, PM2.5, PM10, and TSP were 14.8 ± 5.6, 21.1 ± 9.0, 35.4 ± 14.2 μg m−3, and 45.2 ± 21.3 μg m−3, respectively. The seasonal variations of aerosol concentrations were impacted by the monsoon with the lowest value in summer and the higher values in other seasons. For WSIIs, the annual average concentrations were 6.3 ± 3.3, 2.1 ± 1.2, 3.3 ± 1.5, and 1.6 ± 0.8 μg m−3 in PM1, PM1-2.5, PM2.5–10, and PM>10, respectively. In addition, pronounced seasonal variations of WSIIs in PM1 and PM1-2.5 were observed, with the highest concentration in spring-winter and the lowest in summer. The size distribution showed that SO42−, NH4+ and K+ were consistently present in the submicron particles while Ca2+, Mg2+, Na+ and Cl− mainly accumulated in the size range of 2.5–10 μm, reflecting their different dominant sources. In spring, fall and winter, a bimodal distribution of NO3− was observed with one peak at 2.5–10 μm and another peak at 0.44–1 μm. In summer, however, the fine mode peak disappeared, likely due to the unfavorable conditions for the formation of NH4NO3. For NH4+ and SO42−, their dominant peak at 0.25–0.44 μm in summer and fall shifted to 0.44–1 μm in spring and winter. Although the concentration of NO3–N was lower than NH4–N, the dry deposition flux of NO3–N (35.77 ± 24.49 μmol N m−2 d−1) was much higher than that of NH4–N (10.95 ± 11.89 μmol N m−2 d−1), mainly due to the larger deposition velocities of NO3–N. The contribution of sea-salt particles to the total particulate inorganic N deposition was estimated to be 23.9—52.8%. Dry deposition of particulate inorganic N accounted for 0.95% of other terrestrial N influxes. The annual total N deposition can create a new productivity of 3.55 mgC m−2 d−1, accounting for 1.3–4.7% of the primary productivity in Xiamen Bay. In light of these results, atmospheric N deposition could have a significant influence on biogeochemistry cycle of nutrients with respect to projected increase of anthropogenic emissions from mobile sources in coastal region.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10874-021-09427-8.

Spatio-temporal distribution and source identification of heavy metals in particle size fractions of road dust from a typical industrial district.

Seasonally distribution and source apportionment of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in the road dust (RD) with the four size fraction sizes (<45μm, 45-63μm, 63-150μm and all sizes) in a typical industrial district were investigated using a combination of Moran index, Principal component analysis (PCA), and Positive matrix factorization (PMF). Results showed that from winter to summer, the proportion of the <45μm fraction dust in the total RD mass increased from 6.72% to 15.92% and that of 63-150μm dust particles decreased from 31.13% to 21.76%. The proportion of the enrichment factors (EF) at moderate pollution level in winter was higher than that in summer, especially for Cu, Cd and Pb. Further, the heavy metals were relatively enriched in particles 63-150μm in summer, while in particles <45μm in winter. Spatially, the distribution of heavy metal concentrations was more concentrated in the winter and showed low levels of regional diffusion. Based on the pollution mapping and PCA-PMF, the integrated source appointment showed that the industrial sources are the main sources of Zn, Cd and Pb, and their contributions are higher at a particle below 45μm in winter. The construction source significantly influenced Cr, Mn and Cu in summer with little diversity among particle size ranges. Therefore, the <45μm particles from industrial emission in winter is suggested to be under priority control. And the industrial transformation demonstration area in the Qingshan district should upgrade heavy pollution industry lines and strengthen the monitoring of soot emissions. Further, emissions from coal-fired enterprises should be restricted in winter. Besides, the attention should be paid to avoid urban traffic jams around construction projects and increase enclosed construction ratio.

Effect of Phytoplankton Community Composition and Size Structure on Light Absorption Properties

In the fields of phytoplankton ecology, water optics, and water color remote sensing, phytoplankton absorption properties represent the light absorption capacity of phytoplankton, which affects photosynthesis efficiency and carbon fixation. Here, the biomass, community composition, and the absorption properties of phytoplankton were measured alongside other bio-optical parameters in Lake Tianmu are examined using data collected between January and November 2013 (except February). Based on the relationships between phytoplankton biomass, community composition, and absorption, the effects of abundance, biomass, and equivalent sphere diameter on phytoplankton absorption and specific absorption were revealed. The highest biomass and abundance of phytoplankton were recorded in the autumn and the lowest in the winter. Cryptomonas, Synedra, and Cyclotella were the dominant genera throughout the year. The dominant genera structure type was Bacillariophyta-Cryptophyta in the winter and spring, Bacillariophyta-Chlorophyta-Pyrroptata in the summer, and Cryptophyta-Bacillariophyta-Chlorophyta in the autumn. Phytoplankton diameter was ranked in the order summer>autumn>winter>spring, with mean values of 64.83 μm in summer and 29.54 μm in spring. Phytoplankton absorption coefficients of were ranked in the order autumn > spring > winter > summer, with mean values at 440 nm and 675 nm of (0.66±0.18) m-1 and (0.33±0.10) m-1 in autumn and (0.17±0.02) m-1 and (0.08±0.01) m-1 in summer, respectively. The specific absorption coefficients of the phytoplankton were ranked in the order spring > winter > autumn > summer, with mean values at 440 nm and 675 nm of (0.07±0.02) m2·mg-1 and (0.04±0.01) m2·mg-1 in spring and (0.03±0.004) m2·mg-1 and (0.01±0.002) m2·mg-1 in summer, respectively. Significant linear correlations were found between phytoplankton biomass, abundance, and absorption coefficients. Variations of Bacillariophyta and Cyanophyta biomass caused by temperature explained the seasonal variation in absorption coefficients. The specific absorption coefficient decreased with an increase in equivalent sphere diameter, and variations in phytoplankton community composition explained seasonal changes in the specific absorption coefficient.

Comparation of aerosol optical properties and associated radiative effects of air pollution events between summer and winter: A case study in January and July 2014 over Wuhan, Central China

Differences in aerosol optical properties and associated radiative effects at ultraviolet (UV), visible (VIS), near-infrared (NIR), and shortwave (SW) spectra during haze periods between winter and summer of 2014 in Wuhan were compared in this study. With the development of haze, the average aerosol optical depth increased from 0.371 to 0.769 in winter and from 0.602 to 1.163 in summer. A positive correlation was found between absorbing aerosol optical depth and black carbon, only in winter. The mean fine mode effective radius of aerosols increased from 0.128 μm to 0.166 μm in winter and from 0.179 μm to 0.229 μm in summer, due to hygroscopic growth under high humidity conditions during haze periods. The fine mode particles were more dominant in summer than in winter. The single scattering albedo (SSA) increased significantly in both seasons as a result of the emergence of numerous non-absorbent aerosols when haze occurred. The aerosol radiative effect (ARE) increased from −73.46 W/m2 to −115.38 W/m2 (−96.01 W/m2 to −135.67 W/m2) at the earth's surface, and from −15.09 W/m2 to −32.91 W/m2 (−20.49 W/m2 to −49.13 W/m2) at the top of the atmosphere because of the change from clear air conditions to haze periods in winter (summer). Unusual increases in aerosol radiative effect efficiency (AREE) from −40.78 W/m2 to −43.57 W/m2 and AREE fraction of UV in SW spectrum from 1.9% to 3.3% were found at the top of atmosphere in winter. This exception was probably due to dust aerosols with iron components, which had a strong UV absorption ability. The AREE dependence showed a high dependence on particle size in winter but a greater dependence on the SSA in summer. Back trajectory analysis with active fire areas from Moderate Resolution Imaging Spectroradiometer indicated that the black carbon originated from the North in summer, while active fires in winter were rare.

Supercooled liquid fogs over the central Greenland Ice Sheet

Abstract. Radiation fogs at Summit Station, Greenland (72.58∘ N, 38.48∘ W; 3210 m a.s.l.), are frequently reported by observers. The fogs are often accompanied by fogbows, indicating the particles are composed of liquid; and because of the low temperatures at Summit, this liquid is supercooled. Here we analyze the formation of these fogs as well as their physical and radiative properties. In situ observations of particle size and droplet number concentration were made using scattering spectrometers near 2 and 10 m height from 2012 to 2014. These data are complemented by colocated observations of meteorology, turbulent and radiative fluxes, and remote sensing. We find that liquid fogs occur in all seasons with the highest frequency in September and a minimum in April. Due to the characteristics of the boundary-layer meteorology, the fogs are elevated, forming between 2 and 10 m, and the particles then fall toward the surface. The diameter of mature particles is typically 20–25 µm in summer. Number concentrations are higher at warmer temperatures and, thus, higher in summer compared to winter. The fogs form at temperatures as warm as −5 ∘C, while the coldest form at temperatures approaching −40 ∘C. Facilitated by the elevated condensation, in winter two-thirds of fogs occurred within a relatively warm layer above the surface when the near-surface air was below −40 ∘C, as cold as −57 ∘C, which is too cold to support liquid water. This implies that fog particles settling through this layer of cold air freeze in the air column before contacting the surface, thereby accumulating at the surface as ice without riming. Liquid fogs observed under otherwise clear skies annually imparted 1.5 W m−2 of cloud radiative forcing (CRF). While this is a small contribution to the surface radiation climatology, individual events are influential. The mean CRF during liquid fog events was 26 W m−2, and was sometimes much higher. An extreme case study was observed to radiatively force 5 ∘C of surface warming during the coldest part of the day, effectively damping the diurnal cycle. At lower elevations of the ice sheet where melting is more common, such damping could signal a role for fogs in preconditioning the surface for melting later in the day.

Spatial and Seasonal Variations of PM Concentration and Size Distribution in Manure-Belt Poultry Layer Houses

Abstract. Poultry layer houses are a significant source of particulate matter (PM) emissions, which potentially affect worker and animal health. Particulate matter characteristics, such as concentration and size distribution inside layer houses, are critical information for assessment of the potential health risks and development of effective PM mitigation technologies. However, this information and its spatial and seasonal variations are lacking for typical layer facilities. In this study, two TSI DustTrak monitors (DRX 8533) and an Aerodynamic Particle Sizer (APS 3321) were used to measure PM mass concentrations and number-weighted particle size distributions in two typical manure-belt poultry layer houses in Ohio in three seasons: summer, autumn, and winter. Bimodal particle size distributions were consistently observed. The average count median diameters (mean ±SD) were 1.68 ±0.25, 2.16 ±0.31, and 1.87 ±0.07 µm in summer, autumn, and winter, respectively. The average geometric standard deviations of particle size were 2.16 ±0.23, 2.16 ±0.18, and 1.74 ±0.17 in the three seasons, respectively. The average mass concentrations were 67.4 ±54.9, 289.9 ±216.2, and 428.1 ±269.9 µg m-3 for PM2.5; 73.6 ±59.5, 314.6 ±228.9, and 480.8 ±306.5 µg m-3 for PM4; and 118.8 ±99.6, 532.5 ±353.0, and 686.2 ±417.7 µg m-3 for PM10 in the three seasons, respectively. Both statistically significant (p &amp;lt; 0.05) and practically significant (difference of means &amp;gt;20% of smaller value) seasonal variations were observed. Spatial variations were only practically significant for autumn mass concentrations, likely due to external dust infiltration from nearby agricultural activities. The OSHA-mandated permissible exposure limit for respirable PM was not exceeded in any season. Keywords: Air quality, Particulate matter, Poultry housing, Seasonal variation, Spatial variation.

Assessment of chitin variation in seston of a temperate estuary (Bahía Blanca, Argentina)

Chitin was quantified in seston samples to determine its seasonal and spatial distribution in the estuary of Bahia Blanca. Sampling was conducted at three sites: Puerto Cuatreros, Maldonado, and Canal Vieja in autumn, winter, spring, and summer (2012–2013). Chitin concentrations were 3.79 ± 0.75 and 0.61 ± 0.36 chitin mg L−1 in autumn and winter, respectively. The proportion of chitin in the suspended particular matter (SPM) reached a maximum of 4% in autumn. There were statistical differences in chitin between seasons but not between sampling points. The particulate organic carbon (POC) ranged from 337.25 ± 30.52 µM in winter to 54.93 ± 26.10 µM in summer. The SPM varied from a maximum of 1172.17 ± 17.53 mg L−1 in spring to a minimum 71.42 ± 5.59 mg L−1 in autumn. In both cases, statistical differences were found between seasons but not between sampling points. The results indicated that the concentration of chitin as well as SPM and POC had a strong seasonal trend. The principal component analysis and the canonical analysis on the principal coordinates of environmental variables also highlighted the seasonal variation. The micro-detritus and planktonic organisms (fungi, diatoms, and copepods) in SPM and POC represent a chitinaceous substrate with a great importance for the study of the incorporation of compounds of nitrogen and carbon to the Bahia Blanca system.

Physiological Functions and Metabolism of Endogenous Ethanol and Acetaldehyde in the Reindeer

This study addresses for the first time the seasonal (winter–summer) dynamics of endogenous ethanol (EE) and acetaldehyde (EA) blood levels as well as of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities and catalytic properties in the liver of the reindeer. EE blood level was 1.89 ± 0.11 mM in summer and 1.41 ± 0.10 mM (i.e. 1.34 times lower) in winter (p< 0.05). Seasonal dynamics of EA blood levels was opposite: 3.06 ± 0.28 μM in summer and 12.62 ± 0.76 μM (i.e. 4.12 times higher) in winter (p< 0.05). In winter, there was a decrease in activities of ADHII in the acetaldehyde reduction reaction (4.0 times) and ALDH (3.3 times) in the liver (p< 0.05). This led to an increased winter blood level of EA in cold-adapted animals. Our results suggest that EE and EA, as interrelated metabolites, make up one of the systems that regulate the metabolic rate and eventually reduce the intensity of energy metabolism in the reindeer. This consi derably extends the possibilities for northern species to exist under extreme environmental conditions of cold regions. Apparently, a major ph ysiological function of the system that includes EE, EA and relevant enzymes is to increase cold tolerance of an organism due to the inhibitory effect of EA on mitochondrial terminal oxidation which reduces the intensity of aerobic processes.

Seasonal variations in physical characteristics of aerosol particles at the King Sejong Station, Antarctic Peninsula

Abstract. Seasonal variability in the physical characteristics of aerosol particles sampled from the King Sejong Station in the Antarctic Peninsula was investigated over the period between March 2009 and February 2015. Clear seasonal cycles for the total particle concentration (CN) were observed. The mean monthly concentration of particles larger than 2.5 nm (CN2.5) was highest during the austral summer, with an average value of 1080.39 ± 595.05 cm−3, and lowest during the austral winter, with a mean value of 197.26 ± 71.71 cm−3. The seasonal patterns in the concentrations of cloud condensation nuclei (CCN) and CN coincide, with both concentrations being at a minimum in winter and maximum in summer. The measured CCN spectra were approximated by fitting a power-law function relating the number of CCN for a given supersaturation (SS) to each SS value, with fitting coefficients C and kT. The values for C varied from 6.35 to 837.24 cm−3, with a mean of 171.48 ± 62.00 cm−3. The values for kT ranged from 0.07 to 2.19, with a mean of 0.41 ± 0.10. In particular, the kT values during the austral summer were higher than those during the winter, indicating that aerosol particles are more sensitive to SS changes during summer. Furthermore, the annual mean hygroscopicity parameter, κ, was estimated as 0.15 ± 0.05, for a SS of 0.4 %. The effects of the origin and pathway travelled by the air mass on the physical characteristics of the aerosol particles were also determined. The modal diameter of aerosol particles originating in the South Pacific Ocean showed a seasonal variation varying from 0.023 µm in winter to 0.034 µm in summer for the Aitken mode, and from 0.086 µm in winter to 0.109 µm in summer for the accumulation mode.

Impact of environmental factors on milk β-hydroxybutyric acid and acetone levels in Holstein cattle associated with production traits

The objective of this study was to estimate the environmental factors affecting milk β-hydroxybutyric acid (BHBA) and acetone (Ac) concentrations in Holstein cattle. A total of 264,221 test-day records collected from the Korea Animal Improvement Association (KAIA) during the period of 2012 to 2014 were used in this study. Analysis of variance (ANOVA) was performed to determine the factors significantly affecting ketone body concentrations. Parameters considered in the model were season of test, season of calving, parity, lactation stage, and milk collecting time (AM and PM). According to the ANOVA, the R² for milk BHBA and Ac were 0.5226 and 0.4961, respectively. ‘Season of test’ showed a considerable influence on ketone body concentration. Least square (LS) means for milk BHBA concentrations was the lowest (39.04 μM) in winter while it increased up to 62.91 μM in summer. But Ac concentration did not significantly change along with ‘season of test’. The means of milk BHBA and Ac concentrations were high at first lactation stage, low around second lactation stage, and then gradually increased. Cows milked in the morning had lower mean BHBA and Ac concentrations (48.49 μM and 121.69 μM, respectively) in comparison to those milked in the evening (53.46 μM and 130.42 μM, respectively). The LS means of BHBA and Ac slightly increased over parities. These results suggest that proper maintenance of milk collection, herd management programs, and evaluation of ketone body levels in milk should be considered for the efficient management of resistance to ketosis.

Concentrations and Size Distributions of Water-soluble Inorganic Ions in Aerosol Particles in Taiyuan, Shanxi

Size-resolved filter samples were collected in Taiyuan every other week from June 2012 to May 2014. The mass concentrations of water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3- and SO42-) were measured by ion chromatography. The results showed that the total concentrations of measured water-soluble ions were (15.39±9.91), (21.10±15.49) and (36.34±18.51) μg·m-3 in PM1.1, PM2.1 and PM9, respectively. In PM1.1 and PM2.1, secondary water-soluble ions (SO42-, NO3- and NH4+) comprised 87.59% and 86.30% of all water-soluble ions, respectively, while in PM9, SO42- and Ca2+ comprised 32.78% and 28.54% of all water-soluble ions, respectively. SO42- and NH4+ had higher concentrations in winter and summer, and lower in spring and autumn. NO3-, K+and Cl- presented similar seasonal variation with a descending order of winter >autumn >spring >summer, and Ca2+ and Mg2+ followed the sequence of spring >winter >autumn >summer. SO42- and NH4+ showed a unimodal size distribution and the peak in the fine mode shifted from 0.43-0.65 μm in spring and autumn to 0.65-1.1 μm in summer. NO3- showed a bimodal size distribution. NO3- and NH4+ were dominated by the fine mode peaking at 0.43-2.1 μm in winter, and NO3- was dominated by the coarse mode peaking at 4.7-5.8 μm in summer. K+, Na+and Cl- also showed a bimodal size distribution with the fine mode at 0.43-1.1 μm and the coarse mode at 4.7-5.8 μm. Ca2+, Mg2+ and F- were unimodal with the peak in the coarse mode of 4.7-5.8 μm. On heavily polluted days, the mass concentrations of secondary water-soluble ions and Cl- accumulated, and secondary water-soluble ions were unimodal with the peak in the fine mode of 1.1-2.1 μm. However, on clear days, secondary water-soluble ions showed a bimodal size distribution with the fine mode at 0.43-0.65 μm and the coarse mode at 4.7-5.8 μm. The peak of secondary water-soluble ions in the fine mode shifted. PCA analysis showed that the sources of water-soluble ions were dominated by the secondary formation, coal combustion, industrial emission, biomass burning, and soil particles or falling dust.

Distribution Characteristics of Water-soluble Ions in Size-segregated Particulate Matters in Taiyuan

The distributions of size-segregated particles (PM10) and water-soluble ions (WSIs) in Taiyuan were studied from July 2014 to April 2015 by TE-235 aerosol sampling and ion chromatography analyzing. As the results shown, the daily PM10 level was 173.7 μg·m^-3, which exceeded the Grade Ⅱ limitation value in the Ambient Air Quality Standard (150 μg·m^-3, GB 3095-2012). PM10 levels varied seasonally, and its were 199.1 and 194.2 μg·m^-3 in winter and spring, respectively, which were much higher than those in summer. The PM10 size-segregated was bimodal distribution for the range of 0-0.95 and 3.0-7.2 μm. The concentration of WSIs was the highest in winter, followed by summer and spring. SO4^2-, NO3^- and NH4⁺ were the main water soluble ions and accounted for 66% to 80% of the total WSIs. SO4^2-, K⁺, NH4⁺ and Cl^- showed a unimodal distribution at <0.95 μm in all samples, while Ca²⁺ and Mg²⁺ showed a bimodal distribution at <0.95 μm and 3.0-7.2 μm. NO3^- showed a unimodal size distribution at <0.95 μm in winter and spring, compared with a bimodal distribution at <0.95 μm and 3.0-7.2 μm in summer. By the correlation analysis, PM10 and WSIs decreased with the increase of wind speed in summer and winter other than in spring for the road-dust re-suspension by strong wind. Based on the ratio analysis of NO3^-/SO4^2- and Mg²⁺/Ca²⁺, coal combustion was the main source of NO3^- and SO4^2-, while Mg²⁺ and Ca²⁺ were mainly from the dust and coal combustion.

Seasonal Variation of Aerosol Optical Properties in an Urban Site of the Yangtze Delta Region of China

ABSTRACTThe characteristics of aerosol optical properties during 2012 at Hangzhou (30°14′N, 120°10′E), an urban site in the Yangtze Delta Region of China, were analyzed, including aerosol scattering and absorption coefficients, aerosol optical depth (AOD), Angstrom exponent (α), single scattering albedo (SSA), and aerosol size distribution. Both aerosol absorption and scattering coefficients were lowest in summer; the highest absorption coefficient was observed in autumn; while the scattering was highest in winter. There were no significant differences in the seasonal average of AOD, with values of approximately 1.0 in spring, autumn and winter, and 0.72 in summer. The averaged Angstrom exponent was found to be relatively high throughout the year, with a minimum value of 1.14 in spring and a maximum of 1.35 in autumn. The fine modes of the aerosol volume size distributions showed the highest peak around radius 0.15 µm in spring, autumn and winter, and radius 0.25 µm in summer, while the coarse modes showed maximum peaks at radius 2.9 µm in all seasons. The volume concentrations of coarse mode aerosols over Hangzhou were highest in spring compared with other seasons. The mean total SSA values were 0.89, 0.93, 0.89 and 0.88 at 440 nm for spring, summer, autumn and winter, respectively, indicating that the aerosols were mainly composed of scattering particles in Hangzhou. Furthermore, it was found continuous pollution events appeared in East China as a result of biomass burning during June 10–13 in 2012. The main causes of extremely severe air pollution and poor visibility in Hangzhou were related to the long-distance transport of pollutants, local pollution emission and stagnant weather conditions. Aerosol optical properties exhibited high value in absorption AOD and high aerosol volumes, low SSA in coarse mode after biomass burning.

The contribution of outdoor particulate matter (PM1, PM2.5, PM10) to school indoor environment

The contributions of outdoor and indoor sources to the indoor concentrations of particulate matter (PM1, PM2.5, and PM10) were investigated in a secondary school in Wroclaw, Poland. PM measurements were performed one week per month from December 2009 to October 2010. The sizes of the aerosols generated form indoor sources were in the range of 1–2.5 µm in winter and 2.5–10 µm in summer. It was found that the indoor PM1 concentrations in the school were mostly due to infiltration, with an infiltration factor of 0.65 in winter and 0.68 in summer. These findings, complemented with single particle analyses (using electron probe X-ray microanalysis) revealed that the finest particles, mostly infiltrated from outdoor air, were dominated by organic carbon, sulphates and that organic carbon particles were associated with fly ash or soil dust. Organic carbon was also associated with larger particles of fly ash or soil dust. As part of mineral dust calcium carbonate, salt particles and aluminosilicates were identified. Thus, it is necessary to evaluate the health risks posed to school children associated with the high exposure to indoor PM containing potentially toxic materials in this and probably other schools.

Variations in aerosol microphysical parameters of the surface air layer in the “ocean-continent” transitional zone

This article provides the study results of variations in microphysical parameters of atmospheric aerosol in the surface layer of the “ocean-continent” transitional zone. The analyzed data were obtained during the period from August 1, 2010, to December 31, 2012, at the lidar station of the Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences (IACP FEB RAS), Vladivostok. Mass concentrations of fine aerosol and black carbon and particle size distribution functions typical for the region under study were obtained. In winter, with strong north winds and low relative humidity (50 ± 20)%, dry continental aerosol predominates, and values of the aerosol number density Na are increased, with maxima in the range from 100 and 120 cm−3. In summer, when south winds prevail and the relative humidity attains 98%, sea aerosol predominates and Na took values from (5 ± 5) cm−3 in June, 2011, to (44 ± 20) cm−3 in July, 2011. Periodicity of diurnal variations in the mass and number density of atmospheric aerosol and black carbon are pronounced the best in winter. The modal radius of fine aerosol particles is from 0.275 μm in summer to 0.375 μm in winter, and of coarse aerosol particles, from 1.05 to 2.5 μm, respectively. Seasonal and diurnal variations in the mass concentration of black carbon MBC are the most stable; its values vary from (0.5 ± 0.5) μg/m3 in the early summer to (3.0 ± 2.0) μg/m3 in January–February. It has been ascertained that diurnal variations in MBC in Siberia (Tomsk) and in the “ocean-continent” transitional zone (Vladivostok) are similar in shape, but the amplitude of variations is higher in the latter case and is maximal in winter.

Chemical characteristics of size-resolved PM 2.5 at a roadside environment in Beijing, China

Size-resolved particulate matter in the three size ranges (0.2–0.5 μm, 0.5–1.0 μm, and 1.0–2.5 μm) were collected at a roadside site in Beijing during and after the 2008 Olympic Games. The concentrations of PM mass, 14 elements, 3 major inorganic ions, and carbonaceous species were determined. The main contributors to PM 2.5 were crustal sources, vehicle emissions, secondary aerosol formation along with coal combustion, biomass from burning, and industrial processes, with vehicle emissions contributing more to roadside PM 2.5 than in the urban areas. The peaks at 0.5–1.0 μm in summer for PM mass and inorganic ions were most likely due to secondary aerosol formation, whereas the peaks at 0.2–0.5 μm in winter for PM mass and some elements were probably attributed to combustion from heating sources. The temporary control measures applied during the Olympics showed different effects on various emission sources and chemical species.

Seasonal variation of columnar aerosol optical properties in Yangtze River Delta in China

In order to understand the seasonal variation of aerosol optical properties in the Yangtze River Delta, 5 years of measurements were conducted during September 2005 to December 2009 at Taihu, China. The monthly averages of aerosol optical depth were commonly >0.6; the maximum seasonal average (0.93) occurred in summer. The magnitude of the Angstrom exponent was found to be high throughout the year; the highest values occurred in autumn (1.33) and were the lowest in spring (1.08). The fine modes of volume size distribution showed the maxima (peaks) at a radius of ∼0.15 µm in spring, autumn, and winter; at a radius of ∼0.22 µm in summer. The coarse modes showed the maxima (peaks) at a radius of 2.9 µm in spring, summer, and autumn and at a radius of 3.8 µm in winter. The averages of single-scattering albedo were 0.92 (spring), 0.92 (summer), 0.91 (autumn), and 0.88 (winter). The averages of asymmetry factor were found to be larger in summer than during other seasons; they were taken as 0.66 at 440–1020 nm over Taihu. The real part of the refractive index showed a weak seasonal variation, with averages of 1.48 (spring), 1.43 (summer), 1.45 (autumn), and 1.48 (winter). The imaginary parts of the refractive index were higher in winter (0.013) than in spring (0.0076), summer (0.0092), and autumn (0.0091), indicating that the atmosphere in the winter had higher absorbtivity.

Reproductive cycle of the sea cucumber Psolus patagonicus Ekman 1925, off Mar del Plata, Buenos Aires, Argentina

The reproductive cycle of Psolus patagonicus Ekman 1925 was studied. The species exhibits an annual reproductive cycle with one reproductive period in austral summer (February–March). During spring and summer, females showed the highest gonad-index (GI) values, while the GI values of males did not vary significantly throughout the year. Males had higher GI values than females. Maximum oocyte diameters ranged from less than 300 µm in spring to 900 µm in summer. In February, there is an increase in phytoplankton bloom for the bottom community in which P. patagonicus inhabits. The annual range in water temperature is small (6–7°C). Spawning coincided with increase in available food rather than the increase in water temperature.