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The widespread presence of organic aerosols (OA) in the atmosphere and their dominant role in climate forcing are increasingly recognized. Measurements from the high‐altitude region provide insights into the natural processes and long‐range transport of aerosols. We studied water‐soluble organic compounds in PM1.1 during January‐March 2020 and February‐April 2021 at Ponmudi (8.8°N and 77.1°E), a tropical hill station (960 m a.s.l.) located on the Western Ghats of India. The 5‐day backward trajectories of air masses presented that continental and marine sources impacted the site during the campaign, and thus we classified samples as mixed and marine air masses. Their molecular fingerprints revealed the prevalence of oxalic acid (C2), followed by terephthalic acid in mixed air mass and malonic (C3) or succinic (C4) acid in maritime air mass aerosol samples. This feature and the phthalic to azelaic acid ratio, as well as the C3 to C4 and fumaric to maleic acid ratios, evidenced that water‐soluble OA were of anthropogenic origin and less photochemically aged in mixed air mass samples, whereas they derived from biogenic sources and more photochemical aging in marine air mass samples. However, we found their comparable contributions in water‐soluble organic carbon under mixed and marine air masses. Linear correlations between C2 relative abundance and its ratios with the precursor compounds implied that the oxidation of precursors to oxalic acid occurs during atmospheric transport. The results revealed that the input of anthropogenic and biogenic precursors followed by atmospheric processing controlled the burden of water‐soluble OA across the Western Ghats. Plain Language Summary: Dicarboxylic acids (DCAs), oxocarboxylic acids and dicarbonyls are ubiquitous water‐soluble components of organic aerosol (OA) that can serve as cloud condensation nuclei and affect the climate of the Earth. We reveal for the first time the molecular fingerprints and sources as well as formation processes of water‐soluble OA in PM1.1 at a tropical hill station in Western Ghats of India. Significant differences in the molecular fingerprints and atmospheric processes of water‐soluble OA were found due to the influence of different air masses. DCAs and related compounds in mixed air mass aerosols originated from anthropogenic sources and produced in the atmosphere by photooxidation during long‐range transport whereas they were of biogenic origin followed by intense photochemical aging of biogenic volatile organic compounds such as isoprene and unsaturated fatty acids during atmospheric transport in marine air mass aerosols. The results revealed that DCAs substantially contribute to water‐soluble OA not only in mixed air mass aerosols but also in marine air mass aerosols at the tropical hill station in the Western Ghats. These findings have implications for assessing climate‐forcing feedback of secondary OA over the Western Ghats that is driven by anthropogenic and biogenic sources followed by photochemical processes. Key Points: Mixed and marine air masses drive the molecular fingerprints of atmospheric water‐soluble organic compounds over the Western GhatsAerosols of mixed air masses comprised dicarboxylic acids (DCAs) of anthropogenic origin and less photochemically processedDCAs were produced from biogenic sources followed by intense photochemical aging in marine air mass aerosols [ABSTRACT FROM AUTHOR]

Abstract The widespread presence of organic aerosols (OA) in the atmosphere and their dominant role in climate forcing are increasingly recognized. Measurements from the high‐altitude region provide insights into the natural processes and long‐range transport of aerosols. We studied water‐soluble organic compounds in PM1.1 during January‐March 2020 and February‐April 2021 at Ponmudi (8.8°N and 77.1°E), a tropical hill station (960 m a.s.l.) located on the Western Ghats of India. The 5‐day backward trajectories of air masses presented that continental and marine sources impacted the site during the campaign, and thus we classified samples as mixed and marine air masses. Their molecular fingerprints revealed the prevalence of oxalic acid (C2), followed by terephthalic acid in mixed air mass and malonic (C3) or succinic (C4) acid in maritime air mass aerosol samples. This feature and the phthalic to azelaic acid ratio, as well as the C3 to C4 and fumaric to maleic acid ratios, evidenced that water‐soluble OA were of anthropogenic origin and less photochemically aged in mixed air mass samples, whereas they derived from biogenic sources and more photochemical aging in marine air mass samples. However, we found their comparable contributions in water‐soluble organic carbon under mixed and marine air masses. Linear correlations between C2 relative abundance and its ratios with the precursor compounds implied that the oxidation of precursors to oxalic acid occurs during atmospheric transport. The results revealed that the input of anthropogenic and biogenic precursors followed by atmospheric processing controlled the burden of water‐soluble OA across the Western Ghats.

Seven cloud water samples were collected from May to October 2018 at the Puy de Dôme station (PUY) in France and analyzed by positive‐ion atmospheric pressure photoionization [(+)APPI] Fourier transform ion cyclotron resonance mass spectrometry. The assigned formulas (ranging from 3,865 to 6,380) were attributed using the multidimensional stoichiometric constraint classification of Rivas‐Ubach et al. (2018, https://doi.org.10.1021/acs.analchem.8b00529) to six main categories (RUCs): LipidC, ProteinC, Amino‐sugarC, CarbohydrateC, NucleotideC, and OxyaromaticC. Back trajectories were calculated by the computing atmospheric trajectory tool (CAT) model to obtain information on the air mass history. Partial least square regressions were performed using chemical data, CAT back‐trajectory calculations and FT‐ICR MS data to analyze the environmental variability of the organic sample composition. ProteinC is correlated with the continental surface for air masses transported within the boundary layer, and Amino‐sugarC is strongly correlated with acetate, NO3− and NH4+, suggesting Anthropogenic sources for amino sugars and proteins. LipidC is correlated with the sea surface for air masses transported within the free troposphere, confirming the long‐range transport of marine biogenic sources. Concerning Oxy‐aromaticC, given the correlations with oxidants and pollutants, as well as anti‐correlations with local influence, we proposed a mechanism of oxidation from remote anthropogenic sources. Plain Language Summary: Clouds were sampled on top of the Puy de Dôme mountain in France to study their chemical composition. Cloud droplets were collected by impaction with samplers specifically designed for that. The seven samples, collected from May to October 2018, were characterized by a high‐resolution mass spectrometry method, revealing thousands of organic compounds carrying carbon, hydrogen, nitrogen, sulfur, and phosphorus atoms, belonging to both natural and anthropogenic sources. Using a recently developed classification method, organic compounds were shared into classes based on their respective numbers of elements to lipids, proteins, amino sugars, carbohydrates, and aromatic compounds. To better understand the variability of the molecular fingerprints of each collected sample, we applied statistical analysis which enabled us to link the history of the air‐masses calculated with a three‐dimensional kinematic trajectory code and the chemical composition of the clouds. For example, proteins were related to the time spent by the air mass above continental surfaces at low altitude (in the boundary layer). Amino sugars and aromatic compounds were strongly correlated with anthropogenic sources. Finally, lipids were correlated with the time spent over the ocean in the free troposphere, confirming potential long‐range transport from marine source. Key Points: Analyzing cloud water by high resolution‐mass spectrometry shows the presence of non‐polar, semi‐polar and phosphorus‐containing compoundsA multidimensional stoichiometric constraint classification was applied to assign molecular formulas according to six main categoriesA statistical study highlights correlations between these categories and air mass history, such as proteins with continental boundary layer [ABSTRACT FROM AUTHOR]

The presence of water-soluble dicarboxylic acids in atmospheric aerosols has a significant influence on the regional radiative forcing through direct aerosol effect and cloud formation process. Fine aerosol (PM 2.5 ) samples collected in central Alaska (Fairbanks: 64.51°N and 147.51°W) during summer of 2009 were measured for water-soluble diacids (C 2 –C 12 ), oxoacids (C 2 –C 9 ) and α-dicarbonyls (C 2 –C 3 ) as well as elemental carbon (EC), organic carbon (OC) and water-soluble OC (WSOC) to assess their sources and formation processes. We found the predominance of oxalic acid (C 2 ) followed by malonic (C 3 ) and succinic acid (C 4 ) in Alaskan aerosols. Higher C 3 /C 4 diacid ratios (ave. 1.2) in Alaskan aerosols than those reported for fresh aerosols emitted from fossil fuel combustion (ave. 0.35) and biomass burning (0.51–0.66) suggest that organic aerosols in central Alaska were photochemically processed. The relatively high correlations of major diacids and related compounds with levoglucosan ( r = 0.80–0.99) than those with 2-methylglyceric acid ( r = 0.59–0.98) suggest that they were significantly produced from biomass burning emission. Strong correlations of C 2 with normal-chain saturated diacids (C 3 -C 9 : r = 0.80–0.98), glyoxylic acid (ωC 2 : r = 0.95) and methylglyoxal (MeGly: r = 0.88), together with strong correlations of solar radiation with ratio of C 2 to C 2 –C 12 diacids ( r = 0.83), ωC 2 ( r = 0.80) and MeGly ( r = 0.82) suggest that oxalic acid in PM 2.5 aerosol was produced by the photooxidation of higher homologous diacids, glyoxylic acid and methylglyoxal in the atmosphere of central Alaska. These results reveal that photochemical processing of organic precursors mainly produced from biomass burning control the water-soluble organic chemical composition of fine aerosols in central Alaska. [ABSTRACT FROM AUTHOR]

Long-lived and short-lived halocarbons have long been known for their adverse effects on atmospheric chemistry, especially ozone depletion that may be directly or indirectly influenced by global climate change. Marine organisms including phytoplankton contribute shorter-lived halocarbon compounds to the atmosphere. Oceans cover more than 70% of the Earth's surface making the marine phytoplankton a significant presence. Changes in the environment will inevitably affect this widely distributed group of organisms. Various predictions have been made about how phytoplankton will respond to climate change, but as yet little is known about the interactions between phytoplankton, climate change and halocarbon emissions. We provide a summary of studies on halocarbon emissions by marine phytoplankton isolated from different climatic zones that includes data from our recent studies on tropical marine phytoplankton. It is important to determine and characterize the contribution of the phytoplankton to the halocarbon load in the atmosphere to allow their interaction with the changing global climate to be understood. Using these data, we compare the range of halocarbons emitted by phytoplankton with halocarbon emission data for seaweeds, a well-known biogenic contributor of short-lived halocarbons. Sørensen's coefficient of similarity of 0.50 was calculated, which suggests that half of the detected halocarbon species present in seaweeds are also present in phytoplankton. [ABSTRACT FROM AUTHOR]

This study aimed to quantify the variability in life cycle greenhouse gas emissions, also called carbon footprint (CF), of open-field tomato production in Iran. Three main emission sources, i.e. material and energy use, biogenic sources, and fertilizer application were evaluated. To this end, data on tomato cultivation from 204 open-field tomato farms in two provinces of Alborz and East Azerbaijan in Iran were obtained using face-to-face questionnaires with tomato farmers. The average CF was 0.2 kg CO 2-eq per kg tomatoes produced, ranging from 0.1 to 0.4 kg CO 2-eq (kg tomato) −1 (5–95 percentile range). Material and energy use contributed most to the total emissions (on average 60%), mainly as a result of fertilizer production and energy required for irrigation. The variability in the tomato yield exerted the largest influence on the variation of CF (47%), followed by variability in fertilizer application (22%) and differences in biogenic emissions between the two provinces (21%). Farms in the Alborz region showed systematically smaller CFs than farms in the East-Azerbaijan region due to the use of modern irrigation systems, less fertilizer use and higher yields. The application of modern irrigation systems and provision of training programs on chemical fertilizer use (soil analysis for farmland N content, crop rotation, and crop rotation with legumes) for open-field tomato farms can help to reduce the CF of tomato production in Iran. [ABSTRACT FROM AUTHOR]

Current advancements in green synthesis of materials especially nanoparticles have led to conservation of natural and non-renewable resources along with reduction in environmental pollution. Development of cost-effective, simple and eco-friendly routes for the synthesis of nanoparticles is very important. All over the world, a wide variety of biogenic sources have been put to trial as a source of green agents to facilitate synthesis process. In addition to this, environmentally benign solvents are also being used these days in order to promote green synthesis. In this review, an attempt has been made to familiarise the readers with the different green routes for the synthesis of nanoparticles. [ABSTRACT FROM PUBLISHER]

The extractable organic matter of sediment samples from six sampling sites in Lake Perdana, Kuala Lumpur, was analyzed to characterize the source inputs. The analysis of aliphatic homologous series indicated that terrestrial higher plant waxes can be assigned as the major sources of the identified aliphatic components in the lake sediments. The presence of an unresolved complex mixture of branched and cyclic compounds and a series of hopanes ranging from C to C reflected the contamination by petroleum residues from urban vehicular emissions brought in by runoff and fallout. The steroids present included stenols and stanols and showed an input of organic matter from higher plants. The detected pentacyclic triterpenoids comprised oleanane, ursane, lupane and friedelane skeletons including unsaturated oxygenated, mono-, di- and triaromatic counterparts. They are recognized as biomarkers for angiosperms. The presence of des-A-triterpenoids and their aromatized derivatives as the major diagenetic products of triterpenoids reflected the degradation of natural organic matter in the sediments occurring under mainly anoxic conditions. In addition, the presence of tetrahymanol and ββ-bishomohopan-32-ol indicated a minor algal/plankton and bacterial input to the sediments. [ABSTRACT FROM AUTHOR]

The measurements of a monoterpene (α -pinene) were performed by the PTR-TOF-MS instrument at an urban site of India from mid-January to March 2014. The daytime concentration increased from 0.15 ppb in the second-half of January to 0.40 ppb in the second-half of March. Both the nighttime and daytime ratios of α -pinene/benzene in the second-half of March were 2–3 times higher their respective values from mid-January to first-half of February. The ratios of α -pinene/benzene increased from ∼0.27 ppb ppb−1 at lower temperatures to ∼0.51 ppb ppb−1 at higher temperatures indicating the increase of biogenic emissions in March. The concentration of α -pinene exhibited exponential decline with wind speed, but the rate of decrease in February was about twice that for March. The nighttime ratios of α -pinene/isoprene were greater than those measured in the daytime, suggesting temperature-dependent biogenic emissions of α -pinene. From mid-January to March, the increase of ∼53% in the biogenic contributions of α -pinene were associated with the change in meteorological conditions. Our analysis suggests that the combined effect of the northwest wind flow and higher air temperatures in March favored the emissions of BVOCs from local vegetation. The exceptionally high concentrations of α -pinene up to 6 ppb were measured during the Holi bonfire festival. This is the first study reporting the change in α -pinene during winter-summer transition over India. In the urban regions of developing countries, high emissions of BVOCs from vegetation and of NOx from anthropogenic sources can act as a source of ozone. Diurnal pattern of α -pinene/benzene ratio indicating dependence of biogenic emissions to solar radiation flux and atmospheric temperature during the transition from winter to summer conditions at a semi-arid urban site of India. Image 1 • High mass- and time-resolved measurements of α -pinene using a sensitive PTR-TOF-MS. • Strong dependence of α -pinene concentration on wind parameters and temperature. • Large increase in biogenic emission associated with transition from winter to summer. [ABSTRACT FROM AUTHOR]