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In order to explore the impact of returning corn straw to the field on soil organic carbon composition and yield in semi-arid areas, the long-term positioning experimental field of straw at Qiqihar Branch of Heilongjiang Academy of Agricultural Sciences was used as the research object to analyze the content of soil particulate organic carbon, water-soluble organic carbon and corn yield under three treatments: CK (conventional planting), FM (straw burying and returning) and FG (straw covering and returning). The results showed that clay particles (< 0.053 µm) had the highest organic carbon content in each soil layer under different treatments. The average organic carbon content of sand particles (>0.250 µm) and clay particles (<0.053 µm) in the four soil layers treated with FM by 21.78% and 20.51%, and FG increased by 25.87% and 13.52%, respectively. FM treatment had the highest content of water-soluble organic carbon in each soil layer, with FM>FG>CK in the order of 0-10 and 10-20 cm soil layers.FM treatment increased by 22.73% and 2.48% compared to CK, while FG treatment increased by 38.25% and 26.32% compared to CK, respectively. In the soil layers of 20-30 cm and 30-40 cm, the content of water-soluble organic carbon in the soil was in the order of FM>CK>FG, with FG decreasing by 14.55% and 9.41%, while FM treatment increased by 10.68% and 17.85%. There was no significant difference in spike length, spike diameter and spike row number among different treatments. The order of grain number per spike was FM>FG>CK, and the order of grain water content was FG>CK>FM. The yield order was FM>FG>CK, with FM and FG treatments increasing production by 5.20% and 3.20%, respectively, compared to CK. [ABSTRACT FROM AUTHOR]

This study characterized the water-soluble organic carbon (WSOC) and ionic components of PM2.5 (particles less than 2.5 μm in diameter) from April to June 2016, at Baengnyeong Island The study utilized a particle-into-liquid sampler (PILS) coupled with a total organic carbon (TOC) analyzer and ion chromatography (PILS-TOC-IC). The PM2.5 mean concentration in this study was 23.8±16.7 μg m-3, and the mean of WSOC concentration was 1.6±1.5 μg m-3. Ionic compounds increased by 3.8% in the period in which the air quality standard of PM2.5 (35 μg m-3) was exceeded because the concentration of ionic components increased due to generation by chemical reactions and emissions from a primary source in a nearby urban area. The wind direction and speed were mostly in the northwest and southwest directions and the higher concentration of PM2.5 was also shown in the same directions. In comparison with the previous study, the WSOC/OC ratio was 0.5±0.3 in Baengnyeong Island, which was higher than that at roadside and urban sites and lower than at the background site (Sweden, Aspvreten). It was considered that insoluble OC constituted a major proportion of primary OC that was emitted in urban areas, and the higher WSOC/OC ratios of rural and background sites were affected by inflow. The ratio of nitrate and sulfate in Baengnyeong Island was lower than urban areas in China in other studies, because of emitted aerosols from coal combustion or vehicle emission. The results indicate that Baengnyeong Island was affected by formation of secondary aerosols by chemical reactions and inflow from China as well as domestic emissions. The slope of H+Aersol/SO42- in Baengnyeong Island was 0.079, which was a result of neutralized particle acidity in ambient air. The molar ratio of nitrate and ammonium with sulfate in Baengnyeong Island showed ammonium-rich conditions because ammonium nitrate was increased to homogeneous reaction of ammonia and nitric acid in the gas-phase.

The study represents the seasonal characteristics (carbonaceous aerosols and elements) and the contribution of prominent sources of PM2.5 and PM10 in the high altitude of the eastern Himalaya (Darjeeling) during August 2018–July 2019. Carbonaceous aerosols [organic carbon (OC), elemental carbon (EC), and water soluble organic carbon (WSOC)] and elements (Al, Fe, Ti, Cu, Zn, Mn, Cr, Ni, Mo, Cl, P, S, K, Zr, Pb, Na, Mg, Ca, and B) in PM2.5 and PM10 were analyzed to estimate their possible sources. The annual concentrations of PM2.5 and PM10 were computed as 37±12 μg m−3 and 58±18 μg m−3, respectively. In the present case, total carbonaceous species in PM2.5 and PM10 were accounted for 20.6% of PM2.5 and 18.6% of PM10, respectively, whereas trace elements in PM2.5 and PM10 were estimated to be 15% of PM2.5 and 12% of PM10, respectively. Monthly and seasonal variations in mass concentrations of carbonaceous aerosols and elements in PM2.5 and PM10 were also observed during the observational period. In PM2.5, the annual concentrations of POC and SOC were 2.35 ± 1.06 μg m−3 (66% of OC) and 1.19±0.57 μg m−3 (34% of OC), respectively, whereas annual average POC and SOC concentrations in PM10 were 3.18 ± 1.13 μg m−3 (63% of OC) and 2.05±0.98 μg m−3 (37% of OC), respectively. The seasonal contribution of POC and SOC were ranging from 55 to 77% and 33 to 45% of OC in PM2.5, respectively, whereas in PM10, the seasonal contributions of POC and SOC were ranging from 51 to 73% and 37 to 49% of OC, respectively. The positive relationship between OC & EC and OC & WSOC of PM2.5 and PM10 during all the seasons (except monsoon in case of PM10) indicates their common sources. The enrichment factors (EFs) and significant positive correlation of Al with othe crustal elements (Fe, Ca, Mg, and Ti) of fine and coarse mode aerosols indicate the influence of mineral dust at Darjeeling. Principal component analysis (PCA) resolved the four common sources (biomass burning + fossil fuel combustion (BB + FFC), crustal/soil dust, vehicular emissions (VE), and industrial emissions (IE)) of PM2.5 and PM10 in Darjeeling. [ABSTRACT FROM AUTHOR]

The Picea sp.-Abies sp.-Pinus koraiensis forests(PAP) and Quercus mongolica-Pinus koraiensis forests(QP) in the Heilongjiang Fenglin National Nature Reserve were selected as the research objects, the contents of soil microbial biomass carbon(MBC) and soil water soluble organic carbon(WSOC) were measured to discuss the effects of different forest vegetation on the content of soil labile organic carbon. The results showed: the content of two types of soil labile organic carbon under the two forest types decreased with soil depth deepening. There is no significant difference between PAP and QP in MBC and WSOC(P>0.05). The ratio of MBC to soil organic carbon(SOC) and the ratio of WSOC to SOC in QP were higher than that of PAP. The soil organic carbon density(SOCD) in PAP was significantly higher than that of QP(P<0.05). For the PAP and QP which were composed of specific tree species in Northeast temperate forest, the results showed that there was no significant difference in the content of soil labile organic carbon, but the ratio of soil labile organic carbon to total organic carbon in QP was higher than that of PAP, that meant the stability of soil carbon pool and soil carbon sequestration of PAP was better than that of QP. [ABSTRACT FROM AUTHOR]

Water‐soluble organic carbon (WSOC) makes up a large fraction of organic carbon, which has attracted considerable attention due to its light absorption properties and effects on human health. However, the poorly constrained sources and light absorption properties of WSOC give rise to large uncertainties in its effects on climate and health, especially in regions with high pollutant loading. Here, we investigated the sources and light absorption properties of WSOC in 10 cities across China by dual carbon isotope analysis and UV−visible spectrophotometry, respectively. Despite a dominant contribution of nonfossil sources, the fossil source contribution to WSOC was higher in China than in other regions of the world. The average mass absorption efficiency of WSOC at 365 nm (MAE365) the fossil source contribution of WSOC were 1.13 ± 0.37 m2/gC and 39.9 ± 9.4%, respectively; both values were higher in northern than southern China. The nonfossil source contribution and δ13C of WSOC exhibited significant seasonal variations, with higher values in cold seasons, likely in association with enhanced corn residue burning. In addition, higher MAE365 in the cold seasons (fall and winter) was strongly related to enhanced biomass burning emissions. However, the fossil source contribution of WSOC showed a positive relationship with MAE365 in the cold seasons. This may be because the primary fossil WSOC emitted directly by coal combustion and the secondary fossil WSOC generated under the high NOx conditions in the cold seasons would enhance the color of the entire WSOC. To limit the impacts of WSOC on regional climate and human health, it is suggested that mitigation strategies should consider spatiotemporal variation in WSOC sources, its light absorption properties, and the various formation pathways. Key Points: The fossil fuel contribution and corresponding MAE365 value of water‐soluble organic carbon (WSOC) were higher in northern than southern ChinaHigher 14C and 13C of WSOC in cold seasons may be related to corn residue burningPrimary coal combustion emissions and secondary fossil WSOC generated under high NOX conditions increase MAE365 of WSOC in cold seasons [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Total carbon content of the atmospheric suspended particulate matters consisted of as high as 89-93% organic carbon (OC) in Ulaanbaatar aerosol without showing seasonal variation. However, limited aerosol measurements have been conducted on these OC rich aerosols particularly for high molecular weight constituents. In order to address the gap above, abundance of high molecular weight humic-like substances (HULIS) in total suspended particulates (TSP) from Ulaanbaatar atmospheric aerosol were determined for the first time. HULIS molecular structure was characterised for different seasons using carbon content and UV absorbance measurements coupled with solid phase extraction methods. Although, HULIS contributions to water soluble organic fraction of the winter and summer aerosols were similar HULIS carbon concentration was higher in winter samples (9-37 mg·L-1) than in summer (2-6 mg·L-1). Consequently quantity of aromatic moieties and degree of aromaticity varied between seasons.

Afforestation, as a tool to mitigate carbon emission is constrained by available land areain several countries, but Iran has the potential of plantation. In doing so, differences in soilstocks between tree species could give an indication of the effects of future managementchanges. Hence, a better understanding of tree species traits on soil properties is required topredict how changes in ecosystems occur with tree species composition. This studyinvestigated the effect of selected tree species on soil properties, carbon sequestrationpotential of tree species across soil profiles (0-200 cm) and evaluated the tree specieseffects on labile soil organic carbon pools to introduce a unique soil quality indicator. Thestudy site was Shalman Research Station in the Hyrcanian forests, northern Iran. Our resultsshowed significant alterations in soil properties by tree species with the greatest changes inthe top soil layer. The greatest cation exchange capacity (CEC) difference (Δ 4.17) wasfound between A. glutinosa and J. polycarpos in 0-20 cm. The greatest differences (Δ 2.58)in mean weight diameter (MWD) of soil layers were found in the top soil layer between A.glutinosa and T. distichum. All species produced also a higher N and organic carbonconcentration in the top soil layer (0-20 cm) in the following order: A. glutinosa > Q.castaneifolia > P. caspica > J. polycarpos > T. distichum > P. taeda. The varied amount oftotal soil organic carbon stocks was greater under Alder (A. glutinosa) and Oak (Q.castaneifolia) than other tree species with 206.24 and 195.26 (Mg.ha-1), respectively; and P.taeda had the lowest amount (136.94 Mg ha-1) across the soil profile. For all labile pools,A. glutinosa and T. distichum had the highest and the lowest percent of labile organiccarbon, respectively. Consequently, the Cmin in the range of 10.11-14.04% and microbialbiomass carbon in the range of 1.05-1.66% shared the highest and lowest proportion of soilorganic carbon across 0-200 cm depth, respectively. We concluded that broadleaf trees hadgreat potential for carbon sequestration across soil depth and among them; alder had higheffect on soil properties and soil organic matter.

This study characterized the water-soluble organic carbon (WSOC) and ionic components of PM2.5 (particles less than 2.5 µm in diameter) from April to June 2016, at Baengnyeong Island The study utilized a particle-into-liquid sampler (PILS) coupled with a total organic carbon (TOC) analyzer and ion chromatography (PILS-TOC-IC). The PM2.5 mean concentration in this study was 23.8±16.7 µg m-3, and the mean of WSOC concentration was 1.6±1.5 µg m-3. Ionic compounds increased by 3.8% in the period in which the air quality standard of PM2.5 (35 µg m-3) was exceeded because the concentration of ionic components increased due to generation by chemical reactions and emissions from a primary source in a nearby urban area. The wind direction and speed were mostly in the northwest and southwest directions and the higher concentration of PM2.5 was also shown in the same directions. In comparison with the previous study, the WSOC/OC ratio was 0.5±0.3 in Baengnyeong Island, which was higher than that at roadside and urban sites and lower than at the background site (Sweden, Aspvreten). It was considered that insoluble OC constituted a major proportion of primary OC that was emitted in urban areas, and the higher WSOC/OC ratios of rural and background sites were affected by inflow. The ratio of nitrate and sulfate in Baengnyeong Island was lower than urban areas in China in other studies, because of emitted aerosols from coal combustion or vehicle emission. The results indicate that Baengnyeong Island was affected by formation of secondary aerosols by chemical reactions and inflow from China as well as domestic emissions. The slope of H+Aersol/SO42- in Baengnyeong Island was 0.079, which was a result of neutralized particle acidity in ambient air. The molar ratio of nitrate and ammonium with sulfate in Baengnyeong Island showed ammoniumrich conditions because ammonium nitrate was increased to homogeneous reaction of ammonia and nitric acid in the gas-phase. [ABSTRACT FROM AUTHOR]

In this study, the ionic and carbonaceous compounds in PM2.5 were analysed in the small residential city of Chuncheon, Korea. To identify the local sources that substantially influence PM2.5 concentrations, the samples were divided into two groups: samples with PM2.5 concentrations higher than those in the upwind metropolitan area (Seoul) and samples with lower PM2.5 concentrations. During the sampling period (December 2016–August 2018), the average PM2.5 was 23.2 μg m−3, which exceeds the annual national ambient air quality standard (15 μg m−3). When the PM2.5 concentrations were higher in Chuncheon than in Seoul, the organic carbon (OC) and elemental carbon (EC) concentrations increased the most among all the PM2.5 components measured in this study. This is attributable to secondary formation and biomass burning, because secondary OC was enhanced and water soluble OC was strongly correlated with K+, EC, and OC. A principal component analysis identified four factors contributing to PM2.5: fossil-fuel combustion, secondary inorganic and organic reactions in biomass burning plumes, crustal dust, and secondary NH4+ formation.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Water soluble organic carbon (WSOC) can significantly influence the aerosol optical properties and the aqueous phase chemistry in cloudwater, fogwater and aerosol liquid water. Here, we examine how the changing pH (in acidic range) affects the absorption spectra of aqueous extracts from field biomass burning aerosols, under dark conditions and in presence of simulated sunlight illumination. The observation under dark conditions indicates that pH variation from 2 to 5 induces significantly enhanced light absorbance in the wavelength ranges of 235–270 nm and 300–550 nm, whereas the light absorbance decreased in the range of 270–300 nm, which might be partially ascribed to the deprotonation of carboxylic acids and phenols. During the extract photolysis, light absorption exhibits photo-bleaching below 380 nm and photo-enhancement above 380 nm, indicating that at acidic levels (pH = 2–5), the particle extracts could undergo a significant composition evolution leading to a modification of absorptive properties. Meanwhile, after 12 h-photolysis, the acidity ([H + ]) normalized by WSOC concentration in aqueous extracts ([WSOC ae ]) increased with a variation of Δ[H + ]/[WSOC ae ]=(3.7 ± 0.7) × 10 −7  mol mgC −1 (mean ± standard deviation), suggesting the formation of new acidic substances. Although these findings were acquired in aqueous solutions more relevant to cloud and fog water, the similar evolution likely occurs in wetted aerosols. This calls more attention to the effect of acidity on the wetted aerosols in order to better estimate the aerosol radiative forcing. [ABSTRACT FROM AUTHOR]

This study investigated the optical properties of aerosols involved in different meteorological events, including smog and Asian dust days. Carbonaceous components and inorganic species were measured in Seoul, Korea between 25 and 31 March 2012. Based on the measurements, the optical properties of aerosols were calculated by considering composition, size distribution, and mixing state of aerosols. To represent polydisperse size distributions of aerosols, a lognormal size distribution with a wide range of geometric mean diameters and geometric standard deviations was used. For the optical property calculations, the Mie theory was used to compute single-scattering properties of aerosol particles with varying size and composition. Analysis of the sampled data showed that the watersoluble components of organic matter increased on smog days, whereas crustal elements increased on dust days. The water content significantly influenced the optical properties of aerosols during the smog days as a result of high relative humidity and an increase in the water-soluble component. The absorption coefficients depended on the aerosol mixture type and the aerosol size distributions. Therefore, to improve our knowledge on radiative impacts of aerosols, especially the regional impacts of aerosols in East Asia, accurate measurements of aerosols, such as size distribution, composition, and mixture type, under different meteorological conditions are required. [ABSTRACT FROM AUTHOR]

Total carbon content of the atmospheric suspended particulate matters consisted of as high as 89-93% organic carbon (OC) in Ulaanbaatar aerosol without showing seasonal variation. However, limited aerosol measurements have been conducted on these OC rich aerosols particularly for high molecular weight constituents. In order to address the gap above, abundance of high molecular weight humic-like substances (HULIS) in total suspended particulates (TSP) from Ulaanbaatar atmospheric aerosol were determined for the first time. HULIS molecular structure was characterised for different seasons using carbon content and UV absorbance measurements coupled with solid phase extraction methods. Although, HULIS contributions to water soluble organic fraction of the winter and summer aerosols were similar HULIS carbon concentration was higher in winter samples (9-37 mg·L-1) than in summer (2-6 mg·L-1). Consequently quantity of aromatic moieties and degree of aromaticity varied between seasons. [ABSTRACT FROM AUTHOR]

Characteristics and emission budget of carbonaceous species from two distinct post-harvest agricultural-waste (paddy- and wheat-residue) burning emissions have been studied from a source region (Patiala: 30.2°N, 76.3°E; 250 m amsl) in the Indo-Gangetic Plain (IGP), Northern India. The PM2.5 mass concentration varies from 60 to 390 µg m−3 during paddy-residue burning (October–November) with dominant contribution from organic carbon (OC≈33%), whereas contribution from elemental carbon (EC) centres at ~4%. Water-soluble organic carbon (WSOC) accounts for about 50% of OC. In contrast, mass concentration of PM2.5 during the period of wheat-residue burning (April–May) is significantly lower, varies from 18 to 123 µg m−3 and mass fractions of EC and OC are 7 and 26%, respectively. The diagnostic ratios of OC/EC (11±2), WSOC/OC (0.52±0.02), nss-K+/OC (0.06±0.00) and ΣPAHs/EC (4.3±0.7 mg/g) from paddy-residue burning emissions are significantly different than those from wheat-residue burning (OC/EC: 3.0±0.4; WSOC/OC: 0.60±0.03; nss-K+/OC: 0.14±0.01 and ΣPAHs/EC: 1.3±0.2 mg/g). The emission budget of OC, EC and ΣPAHs from post-harvest agricultural-waste burning in the IGP are estimated to be 505±68 Gg/y, 59±2 Gg/y and 182±32 Mg/y, respectively. From a global perspective, crop-residue burning in Northern India contributes nearly 20% of both OC and EC to the total emission budget from the agricultural-waste burning.

Filter samples collected during winter of 2015–16 from two polluted urban locations (Allahabad and Kanpur) residing within Indo-Gangetic plain (IGP) showed high levels of water-soluble organic aerosols (WSOA). Total organic aerosols (OA) in submicron fraction, measured at Kanpur in real time via Aerosol Mass Spectrometer also showed substantially high concentration levels. WSOA to OA contribution in Kanpur was found to be very high (around 55%) indicating significant contributions from secondary OA (SOA). On average, WSOA oxidation ratio (O/C) was found to be higher (15–20%) in Kanpur than at Allahabad. WSOA from Allahabad was found to be following a much shallower slope (− 0.38) in Van Krevelen diagram (H/C vs O/C plot) than Kanpur (− 0.58). These differences suggest different composition and chemistry of WSOA at these two different locations. O/C ratios of WSOA were found to be much higher (~ 40%) than that of OA and independent of WSOA loading. Higher OA loadings were found to be associated with less oxidized primary OAs (POA) and culminated into lower WSOA/OA ratios. The presence of organo sulfate in filter samples from both locations indicate a significant amount of aqueous processing of organics. Concentrations and characteristics of water insoluble OA (WIOA) in Kanpur revealed that although they are present in significant quantity, their oxidation levels are much (almost 3 times) lower than that of WSOA. This finding indicates that less oxidized OAs are less soluble in line with the conventional wisdom. This study provides the first insight into oxidation levels and evolution of WSOA from India and also explores the interplay between WSOA and OA characteristics based on AMS measurements. [ABSTRACT FROM AUTHOR]

Changes in the content of (polycyclic aromatic hydrocarbons) PAHs and transformation of humic substances during composting of maize straw with sewage sludge and biochar amendment were investigated. Biochar was applied as an agent for improving physical and chemical properties of the composting mix. The composting process has lasted 140 d and was carried out in laboratory conditions. The total content of organic carbon, its soluble forms in hot and cold water, as well as fractional composition of humic substances, and the group of 16 PAHs were investigated during the study. The major changes in the content of individual PAHs were noticed in the first 20 d when the temperature of composting mixtures reached 60°C. Biochar is the source of PAHs, but in the biochar-enriched combination the greatest reduction of the content of those compounds was noticed. The lowest decrease of PAHs concentration was detected in the case of maize straw compost characterized by the smallest volume of mesopores. The content of organic carbon soluble in hot water in the composted materials ranged from 15.1% to 20.2%, whereas in cold water extracts varied from 3.6% to 4.8%, as compared with the total Corg concentration. The humic acid:fulvic acid ratio (Cha:Cfa) indicating the organic matter decomposition was highest in the combination where the greatest reduction of PAHs was observed. The biochar-enriched compost was characterized by the largest population of fungi and presumably this group of microorganisms was responsible for effective PAH degradation. [ABSTRACT FROM AUTHOR]

In this study we observed the role of ammonium ion (NH 4 + ) and transition metals (Fe, Mn, Cr, and Cu) present in ambient submicron particles in stabilizing and enhancing the yield of water soluble organic carbon (WSOC). A good correlation of WSOC with transition metals and NH 4 + was found ( R 2 = 0.87 and 0.71), respectively within foggy episode collected ambient PM 1 (particles having aerodynamic diameter ≤1.0 μm) suggesting plausibleness of alternate oxidation (primarily various carbonyls into their respective organic acids, esters and other derivatives.) and aging mechanisms. Molar concentration of ammonium ion was observed to be exceeded over and above to require in neutralizing the sulphate and nitrate which further hints its role in the neutralization, stabilization and enhancement of subset of WSOC such as water soluble organic acids. Transition metals were further apportioned using enrichment factor analysis. The source of Fe, Mn, and Cr was found to be crustal and Cu was tagged to anthropogenic origin. This study also described the plausible role of significant predictors (Fe and Cu) in the secondary organic aerosol (SOA) formation through effect of Fenton chemistry. Mass-to-charge ratio of identified oxalic acid from our published recent field study (carried out from same sampling location) was used for understanding the possible metallo-organic complex with Fe supports the substantial role of Fe in SOA formation in the deliquescent submicron particles facilitated by aqueous-phase chemistry. [ABSTRACT FROM AUTHOR]

Glomalin related soil protein (GRSP) is a hydrophobic glycoprotein that is significant for soil organic carbon (SOC) persistence and sequestration, owing to its large contribution to SOC pool and long turnover time. However, the contribution of GRSP to dissolve OC (DOC) leach from soil is not yet comprehensively explored, though it could have implication in understanding SOC dynamics. We, therefore, aim to measure the contribution of GRSP to DOC, in a range of land uses and climatic seasons in the dry tropical ecosystem. Our results demonstrated that a significant proportion of GRSP (water soluble GRSP; WS-GRSP) leached with DOC (7.9–21.9 mg kg -1 ), which accounts for 0.2–0.23% of soils total GRSP (T-GRSP). Forest exhibited significantly higher WS-GRSP and DOC leaching than fallow and agriculture. WS-GRSP and DOC accumulations were higher in the dry season (summer and winter) than in rainy. The extent of seasonal variations was higher in forest than in other two land uses, indicating the role of vegetation and biological activity in soil dissolve organic matter (DOM) dynamics. The regression analysis among WS-GRSP, T-GRSP, DOC and SOC prove that the accumulations and leaching of GRSP and other soil OM (SOM) depend on similar factors. The ratio of WS-GRSP-C to DOC was higher in agriculture soil than in forest and fallow, likely a consequence of altered soil chemistry, and organic matter quantity and quality due to soil management practices. Multivariate analysis reflects a strong linkage among GRSP and SOC storage and leaching, soil nutrients (nitrogen and phosphorus) and other important soil properties (pH and bulk density), suggesting that improving GRSP and other SOM status is an urgent need for the both SOC sequestration and soil health in dry tropical agro-ecosystems. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the potential of water soluble organic carbon (WSOC) in CCN activation under restricted anthropogenic emissions over a high altitude station, Darjeeling (27.01° N and 88.15° E,∼2200 amsl and covered with huge coniferous forests) in the eastern parts of Himalaya in India. We measured CN, CCN, and ultrafine WSOC (WSOC 0.1) during April–May 2020 (COVID-19 lockdown) and compared with the normal period (April–May 2019) to investigate the relative dominance of biogenic over anthropogenic emissions to the aerosol-CCN activation. Though an expected significant decline (53%) in CN concentration was observed, CCN exhibited ∼17% increase during the lockdown period. The activation ratio (AR: CCN/CN) jumped from 0.30 during normal to 0.72 during the lockdown period. The aerosol solubility was also found to be increased during the lockdown period (∼27% decrease in the k- parameter (k)). Lockdown-WSOC was higher (1.62 μg m−3) than the normal-WSOC (1.13 μg m−3) and exhibited better regression with CCN in absence of anthropogenic emissions (Lockdown: R2 = 0.83, p < 0.05; Normal: R2 = 0.40, p < 0.05). Here we hypothesize that under restricted fossil fuel emissions during lockdown (57% decline in NO x), surface ozone was increased by 31%, that in turn favored the photochemical oxidation of biogenic VOCs emitted only from coniferous forest cover to produce huge amount of SOC. The ultrafine "biogenic-only" WSOC (under restricted anthropogenic WSOC during lockdown) participated in CCN activation actively and with higher proficiency compared to the normal period. The study bears immense importance of the role of biogenic emissions in cloud droplet formation over this part of the Himalaya under restricted anthropogenic emissions. The present hypothesis could open a new route of aerosol formation and their CCN activation under high deficiency of anthropogenic emissions. • High increase in CCN in restricted anthropogenic emissions • High WSOC formation from biogenic emissions was recorded • Biogenic WSOC enhanced CCN activation [ABSTRACT FROM AUTHOR]

Light absorption characteristics of carbonaceous aerosols are key considerations in climate forcing research. However, in situ measurement data are limited, especially on the Tibetan Plateau (TP) – the Third Pole of the world. In this study, the mass absorption cross section (MAC) of elemental carbon (EC) and water soluble organic carbon (WSOC) of total suspended particles at two high-altitude stations (Lulang station and Everest station) in the Tibetan Plateau (TP) were investigated. The mean MAC EC values at 632 nm were 6.85 ± 1.39 m 2 g −1 and 6.49 ± 2.81 m 2 g −1 at these two stations, both of which showed little seasonal variations and were slightly higher than those of EC of uncoated particles, indicating that the enhancement of MAC EC by factors such as coating with organic aerosols was not significant. The mean MAC WSOC values at 365 nm were 0.84 ± 0.40 m 2 g −1 and 1.18 ± 0.64 m 2 g −1 at the two stations. Obvious seasonal variations of high and low MAC WSOC values appeared in winter and summer, respectively, mainly reflecting photobleaching of light absorption components of WSOC caused by fluctuations in sunlight intensity. Therefore, this phenomenon might also exists in other remote areas of the world. The relative contributions of radiative forcing of WSOC to EC were 6.03 ± 3.62% and 11.41 ± 7.08% at these two stations, with a higher ratio in winter. As a result, both the contribution of WSOC to radiative forcing of carbonaceous aerosols and its seasonal variation need to be considered in radiative forcing related study. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To better understand the sources and atmospheric processing of organic aerosols in the remote marine atmosphere, aerosol (TSP) samples were collected over the North Pacific (13°14′N-53°37′N and 140°46′E-179°54′W) in May–July, 2010 during a cruise of T/V Oshoro Maru , and studied for dicarboxylic acids (C 2 –C 11 ), ω-oxoacids, pyruvic acid and α-dicarbonyls as well as organic and elemental carbon, water-soluble organic carbon and total nitrogen. Over the North Pacific, diacids are most abundant followed by ω-oxoacids and α-dicarbonyls. Although the molecular compositions of diacids are generally characterized by the predominance of oxalic (C 2 ) acid, we found a predominance of succinic (C 4 ) acid in four samples, which were collected in the central northern North Pacific. We consider that photochemical degradation of unsaturated fatty acids emitted from the ocean surface is the main source of C 4 over the central northern North Pacific, where Chlorophyll-a maximized during the cruise. Moreover, seven samples collected in the central northern North and western North Pacific shows predominance of malonic (C 3 ) acid over C 4 , suggesting the photochemical degradation of C 4 to C 3 . Spatial distributions of diacids, ω-oxoacids and α-dicarbonyls together with total carbon and water soluble total nitrogen contents showed higher abundances in the coastal western North Pacific followed by the central northern North and subtropical Pacific, signifying that continental aerosols are transported long distances to the remote marine atmosphere. [ABSTRACT FROM AUTHOR]

CO2, N2OH4 and CH4 are important greenhouse gases, and soils in forest ecosystems are their important sources. Carya cathayensis is a unique tree species with seeds used for high-grade dry fruit and oil production. Understory vegetation management plays an important role in soil greenhouse gases emission of Carya cathayensis stands. A one-year in situ experiment was conducted to study the effects of understory removal on soil CO2, N2O and CH4 emissions in C. cathayensis plantation by closed static chamber technique and gas chromatography method. Soil CO2 flux had a similar seasonal trend in the understory removal and preservation treatments, which was high in summer and autumn, and low in winter and spring. N2O emission occurred mainly in summer, while CH4 emission showed no seasonal trend. Understory removal significantly decreased soil CO2 emission, increased N2O emission and CH4 uptake, but had no significant effect on soil water soluble organic carbon and microbial biomass carbon. The global warming potential of soil greenhouse gases emitted in the understory removal treatment was 15.12 t CO2-e • hm-2 • a-1, which was significantly lower than that in understory preservation treatment ( 17.04 t CO2-e • hm-2 • a-1). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The change characteristics of soil organic carbon and microbial function diversity in Chinese hickory Carya cathayensis stands with different intensive-management durations (5, 10, 15 and 20 years) were studied. The results showed that soil total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) decreased significantly, while the stability of soil C pool increased significantly after the conversion from evergreen and deciduous broadleaf forest to intensively-managed forest (IMF). TOC, MBC and WSOC in the hickory forest soil decreased by 28.4%, 34.1% and 53.3% with 5-year intensive management, and by 38.6%, 48.9% and 64.1% with 20-year intensive management, respectively. The proportions of carboxyl C, phenolic C and aromatic C in the hickory forest soil all increased significantly, and the aromaticity of soil organic C increased by 23.0%. Soil microbial functional diversity decreased greatly after intensive management of Chinese hickory forest. Significant differences in average well color development (AWCD) were found between the 0- and 5-year treatments and the 10-, 15- and 20- year treatments. The microbial diversity indexes (H) and evenness indexes (E) in the 0- and 5-year treatments were much greater than in the 10- and 20-year treatments. Correlation analysis showed that there were significant correlations among soil TOC, WSOC, MBC, AWCD, H and E. [ABSTRACT FROM AUTHOR]

The knowledge deficit of organic aerosol (OA) composition has been identified as the most important factor limiting our understanding of the atmospheric fate and implications of aerosol. The efforts to chemically characterize OA include the increasing utilization of nuclear magnetic resonance spectroscopy (NMR). Since 1998, the functional composition of different types, sizes and fractions of OA has been studied with one-dimensional, two-dimensional and solid state proton and carbon-13 NMR. This led to the use of functional group ratios to reconcile the most important sources of OA, including secondary organic aerosol and initial source apportionment using positive matrix factorization. Future research efforts may be directed towards the optimization of experimental parameters, detailed NMR experiments and analysis by pattern recognition methods to identify the chemical components, determination of the NMR fingerprints of OA sources and solid state NMR to study the content of OA as a whole. [Copyright &y& Elsevier]

Characteristics and emission budget of carbonaceous species from two distinct post-harvest agricultural-waste (paddy- and wheat-residue) burning emissions have been studied from a source region (Patiala: 30.2°N, 76.3°E; 250 m amsl) in the Indo-Gangetic Plain (IGP), Northern India. The PM2.5 mass concentration varies from 60 to 390 µg m-3 during paddy-residue burning (October-November) with dominant contribution from organic carbon (OC33%), whereas contribution from elemental carbon (EC) centres at ~4%. Water-soluble organic carbon (WSOC) accounts for about 50% of OC. In contrast, mass concentration of PM2.5 during the period of wheat-residue burning (April-May) is significantly lower, varies from 18 to 123 µg m-3 and mass fractions of EC and OC are 7 and 26%, respectively. The diagnostic ratios of OC/EC (11±2), WSOC/OC (0.52±0.02), nss-K+/OC (0.06±0.00) and SPAHs/EC (4.3±0.7 mg/g) from paddy-residue burning emissions are significantly different than those from wheat-residue burning (OC/EC: 3.0±0.4; WSOC/OC: 0.60±0.03; nss-K+/OC: 0.14±0.01 and SPAHs/EC: 1.3±0.2 mg/g). The emission budget of OC, EC and SPAHs from post-harvest agricultural-waste burning in the IGP are estimated to be 505±68 Gg/y, 59±2 Gg/y and 182±32 Mg/y, respectively. From a global perspective, crop-residue burning in Northern India contributes nearly 20% of both OC and EC to the total emission budget from the agricultural-waste burning. [ABSTRACT FROM AUTHOR]

By the method of taking space instead of time, an incubation test was conducted to study the characteristics of soil microbial biomass carbon and water soluble organic carbon in the process of natural restoration of Karst forest in Maolan Nature Reserve, Guizhou Province of Southwest China. The soil microbial biomass carbon content and soil basal respiration decreased with increasing soil depth but increased with the process of the natural restoration, soil microbial quotient increased with increasing soil depth and with the process of restoration, and soil water soluble organic carbon content decreased with increasing soil depth. In the process of the natural restoration, surface soil water soluble organic carbon content increased, while sublayer soil water soluble organic carbon content decreased after an initial increase. The ratio of soil water soluble organic carbon to total soil organic carbon increased with increasing soil depth but decreased with the process of restoration. Soil quality increased with the process of restoration. Also, the quality and quantity of soil organic carbon increased with the process of restoration, in which, soil microbial biomass carbon content had the greatest change, while soil water soluble organic carbon content had less change. [ABSTRACT FROM AUTHOR]

Abstract: Desorption kinetics and sources (fossil vs. contemporary) of the water soluble organic carbon (WSOC) component of aerosol particles were examined at two sites on the east coast of the United States. Experiments revealed that WSOC is released either rapidly as one homogeneous pool or via biphasic kinetics with one rapidly and one slowly desorbing pool. The majority (>85%) of WSOC was desorbed within the first 15min of immersion in water, suggesting that this material can be rapidly incorporated into rainwater pre-depositionally or surface waters post-depositionally and transported through watersheds. Radiocarbon (14C) measurements showed that on average 12±4% and 14±2% of WSOC from sites in New York and Virginia, respectively, was derived from fossil sources. By contrast, mass balance calculations revealed water-insoluble organic carbon to have significantly greater fossil contributions. These findings suggest that contemporary biogenic aerosol OC is preferentially incorporated into the aqueous phase and may be transported relatively rapidly through watersheds and aquatic systems. In contrast, the more highly aged and fossil aerosol component remains in particulate form and is more likely to be retained on particles or in soils or aquatic sediments. [ABSTRACT FROM AUTHOR]

Abstract: Earthworms inhabiting arsenic contaminated soils may accelerate the leaching of As into surface and ground waters. We carried out three experiments to determine the impact of passage of As contaminated soil (1150mgAskg−1) through the gut of the earthworm Lumbricus terrestris on the mobility and speciation of As and the effects of earthworm mucus on As mobility. The concentration of water soluble As in soil increased (from 1.6 to 18mgkg−1) after passage through the earthworm gut. Casts that were aged for 56 days still contained more than nine times greater water soluble As than bulk earthworm inhabited soil. Changes were due to increases in As(V) mobility, with no change in As(III). Dilute mucus extracts reduced As mobility through the formation of As–amino acid–iron oxide ternary complexes. More concentrated mucus extracts increased As mobility. These changes, together with those due to the passage through the gut, were due to increases in pH, phosphate and soluble organic carbon. The mobilisation of As from contaminated soils in the environment by cast production and mucus secretion may allow for accelerated leaching or uptake into biota which is underestimated when bulk soil samples are analysed and the influence of soil biota ignored. [Copyright &y& Elsevier]

Bulk aerosols sampled on a weekly basis at two Cairo (Egypt) urban sites from January 2003 to May 2006 were analysed for their chemical composition of major aerosol species (elemental carbon, water soluble/insoluble organic carbon, nitrate, sulphate, ammonium, chloride, sodium and calcium). Data subsequently obtained constitute one of the longest and more detailed dataset related to Cairo aerosols, and offer the opportunity to investigate seasonal trends. Dust aerosols (derived from calcium measurements) displayed maximum concentrations in spring and winter, due to frequent dust storms, but also high background concentration levels (∼50μgm−3) all year long. Within these particles, about 40% on average of Ca2+ was found to be associated with SO4 2−, NO3 − and/or Cl−, pointing out “dust anthropization” processes and their subsequent climatic impact on a regional scale. Seasonal variations of non-dust aerosols, equally distributed between carbonaceous aerosols and ions, were also observed, with concentrations of the order of 100μgm−3 in autumn and winter, and of 60μgm−3 in spring and summer. High concentration levels of non-sea-salt chloride (up to 15μgm−3 on a monthly basis), likely of industrial origin, were observed in autumn and winter. During the autumn “Black Cloud” event, biomass burning aerosols originating from rice straw burning in the Nile Delta have shown to account for 12%, 35% and 50% of Cairo EC, WIOC and WSOC mass concentrations, respectively. Finally, relatively low WSOC/OC ratios (∼1/3) were obtained all the year long, calling for more investigation on the water-solubility of organic aerosols originating from the burning of agricultural waste, and on that of secondary organic aerosols formed in dry urban atmospheres. [Copyright &y& Elsevier]

Aerosol samples were collected at Catania (Italy), from 16 March to 13 June 2005. The sampling was performed using a low pressure five-stage Berner cascade impactor. The samples were analysed for total aerosol mass, Water Soluble Organic Carbon (WSOC), Total Carbon (TC) and main inorganic ionic species. The Water-Insoluble Carbon (WINC) was derived by the difference: TC-WSOC. The samples share some common features: ammonium sulphate and carbon-containing species (both soluble and insoluble) are the largest contributors of fine particle mass, while coarse particles essentially consist of sea-salt, sodium nitrate and unaccounted PM (probably crustal material). The WINC/WSOC ratio decreases from the smallest size range to the large accumulation mode range (0.42–1.2 μm), while the $${\text{nssSO}}^{ = }_{4} $$ and $$ {\text{NH}}^{ + }_{4} $$ contribution rises. The water-insoluble carbonaceous matter is the dominant component in the smallest particles (0.05–0.14 μm). We identified four different aerosol types, corresponding to different sources, contributing to the total particles load of the investigated urban environment: vehicular traffic, producing primary carbonaceous insoluble particles, secondary aerosols, dominating the composition of accumulation mode particles, and marine particles and mineral dust (both important components of the coarse aerosol fraction). [ABSTRACT FROM AUTHOR]

Abstract: Solvent extractable organic compounds (SEOC), organic carbon, elemental carbon and water soluble organic carbon (WSOC) in PM2.5 samples collected in Shanghai, China in 2002 and 2003 were measured to determine the composition and sources of the organic matter in atmospheric aerosols. Distinct seasonal variations were detected with higher concentrations of organic matter in winter. The concentration of total carbon of about 20μgm−3 in winter was about three times the summer value. About 30% of the total carbon was water soluble. Unresolved complex mixture (UCM) and fatty acids were the most abundant components quantified in SEOC, similar to other Chinese cities previously studied. High ratio of UCM to n-alkanes (U:R) and the composition of triterpanes indicated that engine exhaust was a major source of the airborne organic matter. Emissions from coal burning had more impact in the rural areas, according to the U:R value and PAHs composition. Chemical mass balance (CMB) modeling shows that about half of the organic carbon was from engine exhaust and about 15% was from coal burning. No clear spatial variation in the concentration of the organic matter was found between urban and rural areas. Our results showed that due to the rapid urbanization and relocation of industrial plants from urban areas to rural areas in the past 20 years, air pollution in rural areas is becoming a serious problem in Shanghai and the Yangtze River delta. [Copyright &y& Elsevier]

Fluorescein diacetate hydrolyzing activity (FDHA) of soils, both in field moist and air dried, of different agro-ecosystems in alluvial soil was studied. Field moist soils recorded higher values than in air-dried soils, but they showed significant positive correlation (0.93**). FDHA in both soil pretreatments showed positive correlation with organic matter (0.98** for field moist soil and 0.92** for air-dried soil) and clay content (0.85** for field moist soil and 0.82* for air-dried soil) of the soils. Multiple regression analysis showed that the stabilization of FDHA in the studied soils was due to organic matter-enzyme complex. Among the organic matter fractions, humus C plays dominating role to control the FDHA of the soils. [ABSTRACT FROM AUTHOR]

Fluorescence excitation and average molecular weight of 46 water soluble organic matter (WSOC) samples extracted from 20 soil types in eastern China were determined. It was found all samples shared similar spectroscopy. A good linear relationship existed between total organic carbon and excitation in the range of 350 to 450 nm though the content of organic carbon and pH of the samples vary in a wide range. No significant correlation between relative excitation intensity and average molecular weight of WSOC and FA was found, but the partial correlation became significant with pH as the controlling factor for WSOC samples. The relative excitation intensity showed a general trend of increasing from south to north in the study area. The pH value might play an important role in regulating the fluorescent spatial variation of WSOC. [ABSTRACT FROM AUTHOR]

In this study, the ionic and carbonaceous compounds in PM2.5 were analysed in the small residential city of Chuncheon, Korea. To identify the local sources that substantially influence PM2.5 concentrations, the samples were divided into two groups: samples with PM2.5 concentrations higher than those in the upwind metropolitan area (Seoul) and samples with lower PM2.5 concentrations. During the sampling period (December 2016–August 2018), the average PM2.5 was 23.2 μg m−3, which exceeds the annual national ambient air quality standard (15 μg m−3). When the PM2.5 concentrations were higher in Chuncheon than in Seoul, the organic carbon (OC) and elemental carbon (EC) concentrations increased the most among all the PM2.5 components measured in this study. This is attributable to secondary formation and biomass burning, because secondary OC was enhanced and water soluble OC was strongly correlated with K+, EC, and OC. A principal component analysis identified four factors contributing to PM2.5: fossil-fuel combustion, secondary inorganic and organic reactions in biomass burning plumes, crustal dust, and secondary NH4+ formation. [ABSTRACT FROM AUTHOR]