Water-soluble species constitute a significant fraction (up to 60–70%) of the total aerosol loading in the marine atmospheric boundary layer (MABL). The “indirect” effects, that is, climate forcing due to modification of cloud properties depend on the water-soluble composition of aerosols. Thus, the characterization of aerosols over the MABL is of greater relevance. Here, we present 1-year long aerosol chemical composition data of PM10 and PM2.5 at a costal location in the northeastern Arabian Sea (Goa; 15.45°N, 73.20°E, 56 m above the sea level). Average water-soluble ionic concentration (sum of anion and cation) is highest (25.5 ± 6.9 and 19.6 ± 5.8 μg·m−3 for PM10 and PM2.5, respectively) during winter season and lowest during post-monsoon (17.3 ± 9.1 and 14.4 ± 8.1 μg·m−3 for PM10 and PM2.5, respectively). Among water-soluble ionic spices, SO42- ion was found to be dominant species in anions and NH4+ is dominant in cations, for both PM10 and PM2.5 during all the seasons. These observations clearly hint to the contribution from anthropogenic emission and significant secondary inorganic species formation. Sea-salt (calculated based on Na+ and Cl−) concentration shows significant temporal variability with highest contribution during summer seasons in both fractions. Sea-salt corrected Ca2+, an indicator of mineral dust is found mostly during summer months, particularly in PM10 samples, indicates contribution from mineral dust emissions from arid/semiarid regions located in the north/northwestern India and southwest Asia. These observations are corroborated with back-trajectory analyses, wherein air parcels were found to derive from the desert area in summer and Indo-Gangetic Plains (a hot spot for anthropogenic emissions) during winter. In addition, we also observe the presence of nss-K+ (sea-salt corrected), for PM2.5, particularly during winter months, indicating influence of biomass burning emissions. The impact on aerosol chemistry is further assessed based on chloride depletion. Chloride depletion is observed very significant during post-monsoon months (October and November), wherein more than 80 up to 100% depletion is found, mediated by excess sulfates highlighting the role of secondary species in atmospheric chemistry. Regional scale characterization of atmospheric aerosols is important for their better parameterization in chemical transport model and estimation of radiative forcing.
The present study utilized Aspergillus spp. for the synthesis of silver nanoparticles (AgNPs); the developed AgNPs were categorized using analytical techniques, that is, ultraviolet–visible (UV–vis) spectrophotometer, Zeta‐potential, dynamic light scattering (DLS), and transmission electron microscopy (TEM). A sharp peak of 463 nm highlighted the synthesis of AgNPs; further Zeta‐potential of −16 mV indicates stability of synthesized AgNPs. The TEM micrograph showed spherical and hexagonal shapes of synthesized AgNPs of 6–25 nm. The photocatalytic activity of fungal‐mediated AgNPs was evaluated for degradation of reactive yellow dye in the concentration range of 20–100 mg L−1. The results showed efficient degradation of dye using AgNPs in short span of time. For antibacterial activity, synthesized AgNPs, antibiotic, and AgNPs + antibiotic were tested. As per results, the zone of inhibition (ZOI) of AgNPs showed the values of 13 and 10 mm for Escherichia coli and Staphylococcus aureus, respectively. Further, the ZOI of penicillin highlighted the values of 18 and 17 mm for E. coli and S. aureus, respectively. When AgNPs and penicillin were used in combination, a clear synergistic effect was observed; the ZOI showed 0.49‐ and 0.36‐fold increase in area against E. coli and S. aureus, respectively, in comparison with penicillin or AgNPs alone. Further, the leftover biomass (retentate biomass) was used to decolorize the reactive yellow dye at different initial concentration ranging from 20 to 100 mg L−1. It was observed that 1 g L−1 retentate biomass (BR) can effectively remove 82%–100% dye at 20 and 100 mg L−1 initial dye concentration. Results also indicated that with increase in initial reactive dye concentration from 20 to 100 mg L−1, the decolorization capacity of retentate biomass (BR) (at 0.2 g L−1) decreased from 79.2% to 32.3%. However, the use of AgNPs synthesized leftover fungal biomass can be a good option for up taking the additional dyes/contaminants, and also as leftover biomass can be utilized effectively, it can prove to be an excellent approach for environment safety. As the literature studies did not mentioned the further use of retentate biomass, the present study provides an excellent approach for further research on this aspect. Practitioner points Synthesis of AgNPs from Aspergillus spp. and characterized with the help of a U.V‐vis spectrophotometer, a zeta potential, DLS and TEM. The developed AgNPs were used for antibacterial and dye degradation activity. The left over (retentate) fungal biomass was used further for additional dye degradation activity
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