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Air-sea deposition of phosphorus is an important external source of this macronutrient for ocean primary productivity. Although global budgets have shown that atmospheric input of phosphorus is comparable to its riverine supply, studies on regional scale are rather limited. The present article summarizes sources and atmospheric pathway of phosphorus to the ocean surface as a case study of the Northern Indian Ocean. Water-soluble aerosol phosphorus (PInorg) concentrations are significantly high over the Bay of Bengal (BoB) compared to those over the Arabian Sea (ARS). Relative increase in the supply of aerosol-P over BoB is attributed to acid-processing of mineral dust during long-range atmospheric transport in addition to its supply from anthropogenic sources. Our estimate of P-deposition to the Northern Indian Ocean (~1.2 Gmol-P year-1) is comparable to its atmospheric deposition in other oceanic regions such as the North Atlantic and is also consistent with the model-based projections for the Northern Indian Ocean. These results highlight the importance of atmospheric source in influencing the biogeochemical cycle of phosphorus in the Northern Indian Ocean. [ABSTRACT FROM AUTHOR]

The regional air quality, atmospheric chemistry and climate change are largely influenced by the chemical composition of ambient aerosols and more importantly, by their residence time on a spatial and temporal scale. The environmental radionuclide 210Pb (t1/2 = 22.3 years), injected into the atmosphere by in situ decay of its parent nuclide 222Rn (t1/2 = 3.8 days) from ground sources, is highly particle reactive and thus serves as an ideal tracer to assess the residence time of anthropogenic and natural aerosols from ground-based sources. We report on the temporal variability in residence time of ambient aerosols studied from an urban site (Ahmedabad) and a high altitude site (Mt Abu) in western India. The residence time of aerosols, ranging from ~2 to 8 days, is predominantly controlled by regional meteorology and high dust abundance (shorter removal time) in semiarid regions. These observations raise the issue of uncertainty in tracing the source region of atmospheric pollutants based on air-mass back trajectory analyses without knowing their actual residence time for a given time-period over a study region. [ABSTRACT FROM AUTHOR]

Ambient aerosols collected from the marine atmospheric boundary layer of the Bay of Bengal and the Arabian Sea have been studied to assess the fractional solubility of aerosol iron, defined as Fe (%) = Fe/Fe × 100; where Fe is total aerosol iron and Fe is water soluble iron. The mass concentration of Fe over the two oceanic regions is not significantly different. However, the fractional solubility is 1-2 orders of magnitude higher over the Bay of Bengal (1.4-24%) compared to that over the Arabian Sea (0.02-0.4%). The spatio-temporal variability in Fe (%) is attributed to differences in the nature of the mineral dust over the two oceanic regions. The Arabian Sea receives coarse dust from desert regions; whereas transport of alluvial dust from the Indo-Gangetic Plain is a dominant source to the Bay of Bengal. The poor fractional solubility (<1%) of Fe from mineral dust, hitherto overestimated in the literature, is documented for the Arabian Sea. A significant linear relationship ( P-value < 0.001) between Fe (%), Fe and nss-SO over the Bay of Bengal provides evidence for the chemical processing of mineral dust. Furthermore, the role of anthropogenic sources (biomass burning and fossil-fuel combustion) in enhancing the Fe (%) is discernible from the chemical composition of fine mode (PM) aerosols over the Bay of Bengal. The potential impact of these Fe-dust depositions on phytoplankton carbon fixation and surface ocean biogeochemistry is discussed. [ABSTRACT FROM AUTHOR]

The first simultaneous measurements and analytical data on atmospheric concentrations of PM2.5, PM10, inorganic constituents, carbonaceous species, and their optical properties (aerosol optical depth, AOD; absorption coefficient, babs; mass absorption efficiency, σabs; and single scattering albedo, SSA) from an urban site (Kanpur) in the Indo-Gangetic Plain are reported here. Significantly high aerosol mass concentration (>100 μg m-3) and AOD (> 0.3) are seen as a characteristic feature throughout the sampling period, from October 2008 to April 2009. The temporal variability in the mass fractions of carbonaceous species (EC, OC, and WSOC) is pronounced during October-January when emissions from biomass burning are dominant and OC is a major constituent (30%) of PM2.5 mass. The WSOC/OC ratio varies from 0.21 to 0.65, suggesting significant contribution from secondary organic aerosols (SOAs). The mass fraction of SO42- in PM2.5 (Av: 12.5%) exceeds that of NO3- and NH4+. Aerosol absorption coefficient (@ 678 nm) decreases from 90 Mm-1 (in December) to 20 Mm-1 (in April), and a linear regression analysis of the data for babs and EC (n = 54) provides a measure of the mass absorption efficiency of EC (9.6 m² g-1). In contrast, scattering coefficient (@ 678 nm) increases from 98 Mm-1 (in January) to 1056 Mm-1 (in April) and an average mass scattering efficiency of 3.0 ± 0.9 m² g-1 is obtained for PM10 samples. The highest bscat was associated with the dust storm event (April 17, 2009) over northern Iraq, eastern Syria, and southern Turkey; thus, resulting in high SSA (0.93 ± 0.02) during March-April compared to 0.82 ± 0.04 in October-February. These results have implications to large temporal variability in the atmospheric radiative forcing due to aerosols over northern India. [ABSTRACT FROM AUTHOR]

The continental outflow from the Indo-Gangetic Plain and Southeast Asia, during the late NE monsoon (January-March), dominates the transport of chemical constituents to the marine atmospheric boundary layer (MABL) of the Bay of Bengal (BoB). During the rest of the year, prevailing wind regimes and meteorological conditions do not favour the atmospheric transport of continental products. Here we report on the spatiotemporal variability of inorganic phosphorous (PInorg=PO43-) in the MABL and its dry-deposition flux to the surface BoB. On the basis of the abundance of PInorg in PM2.5 (0.1-0.8 nmol m-3) and PM10 (0.3-2.8 nmolm-3), we document its dominant occurrence in the coarse mode (Da ≥ 2.5 μm). The analytical data also provide evidence for the chemical processing of mineral dust by acidic species and mobilisation of PInorg during the long-range atmospheric transport. However, significantly high PInorg/non-sea-salt Ca2+ ratios over the BoB suggest dominant contribution from anthropogenic sources (fertilisers and biomass burning emissions). PInorg concentration over the Arabian Sea is about 4 to 5 times lower and is primarily associated with the mineral dust from desert regions. The dry-deposition flux of PInorg to the BoB varies by one order of magnitude (0.5-5.0 mmol Pm-2 d-1; Av: 0.02 Tg P yr-1). These results have implications to the air-sea deposition of phosphorous over oceanic regions downwind of the pollution sources and impact on the biogeochemistry of surface waters. [ABSTRACT FROM AUTHOR]

A systematic 1-yr chemical data for the fine mode (PM2.5) air-borne particulate matter, collected from a high-altitude site (Mt. Abu, 22.7°N, 74.6°E, 1680 m asl) in a semi-arid region of western India, reveal characteristic temporal variability in the abundance of mineral dust and fractional solubility of aerosol Fe (referred as water-soluble Fe). A notable feature of the data is seen from an inverse relationship between aerosol Fe (range: 50–915 ng m−3) and fractional Fe solubility (range: 0.06–16.1%). A significant increase in the solubility of iron, during wintertime, is also marked by a uniform decrease in the mass fraction of mineral dust. These observations suggest that the advective transport of pollutants and Fe derived from combustion sources is one of the possible causes for the enhanced solubility of iron over a semi-arid region in western India. The relative dominance of anthropogenic sources, during wintertime, is also supported by a two to threefold increase in NH4+ and SO42− as well as enrichment of heavy metals in PM2.5 (ascertained from Pb/Al and Cd/Al ratios). [ABSTRACT FROM AUTHOR]

Temporal and spatial variability in the absorption coefficient (babs, Mm-1) and mass absorption efficiency (MAE, σabs, m²g-1) of elemental carbon (EC) in atmospheric aerosols studied from urban, rural, and high-altitude sites is reported here. Ambient aerosols, collected on tissuquartz filters, are analyzed for EC mass concentration using thermo-optical EC-OC analyzer, wherein simultaneously measured optical-attenuation (ATN, equivalent to initial transmittance) of 678 nm laser source has been used for the determination of MAE and absorption coefficient. At high-altitude sites, measured ATN and surface EC loading (ECs,μg cm-2) on the filters exhibit linear positive relationship (R² = 0.86-0.96), suggesting EC as a principal absorbing component. However, relatively large scatter in regression analyses for the data from urban sites suggests contribution from other species. The representative MAE of EC, during wintertime (Dec 2004), at a rural site (Jaduguda) is 6.1 ± 2.0 m²g-1. In contrast, MAE at the two high-altitude sites is 14.5 ± 1.1 (Manora Peak) and 10.4 ± 1.4 (Mt Abu); and that at urban sites is 11.1 ± 2.6 (Allahabad) and 11.3 ± 2.2 m²g-1 (Hisar). The long-term average MAE at Manora Peak (February 2005 to June 2007) is 12.8 ± 2.9 m²g-1 (range: 6.1-19.1 m²g-1). These results are unlike the constant conversion factor used for MAE in optical instruments for the determination of BC mass concentration. The absorption coefficient also shows large spatiotemporal variability, the lower values are typical of the high-altitude sites and higher values for the urban and rural atmosphere. Such large variability documented for the absorption parameters suggests the need for their suitable parametrization in the assessment of direct aerosol radiative forcing on a regional scale. [ABSTRACT FROM AUTHOR]

The precipitation events (n = 91), collected for 3 years (2000–2002) during the period of SW-monsoon (Jun–Aug) from an urban site (Ahmedabad, 23.0°N, 72.6°E) of a semi-arid region in western India, are found to exhibit characteristic differences in terms of their solute contents. The low solute (<700 μeq L−1) events are either marked by heavy precipitation amount or successive events collected during an extended rain spell; whereas light precipitation events occurring after antecedent dry period are characterized by high solutes (>700 μeq L−1). The ionic composition of low solute events show large variability due to varying contribution of anthropogenic species ( $${\text{NH}}^{ + }_{4} $$ : 1%–74%; $${\text{NO}}^{ - }_{3} $$ : 1%–25%; and $${\text{SO}}^{{2 - }}_{4} $$ : 8%–68%) to the respective ion balance. In high solute events, ionic abundances are dominated by mineral dust (Ca2+ and $${\text{HCO}}^{ - }_{3} $$ ) and sea-salts (Na+ and Cl−). These differences are also reflected in the pH of low solute events (range: 5.2–7.4, VWM: 6.4) and high solute events (range: 6.6–8.2, VWM: 7.3). The comparison of Ca2+/Na+ and nss- $${{\text{nss}} - {\text{SO}}^{{2 - }}_{4} } \mathord{\left/ {\vphantom {{{\text{nss}} - {\text{SO}}^{{2 - }}_{4} } {{\text{Ca}}^{{2 + }} }}} \right. \kern-\nulldelimiterspace} {{\text{Ca}}^{{2 + }} }$$ ratios (on equivalent basis) in rain and aerosols suggests that the ionic composition of high solute events is influenced by below-cloud scavenging; whereas evidence for in-cloud scavenging is significantly reflected in low solute events. The annual wet-deposition fluxes of $${\text{NH}}^{ + }_{4} $$ and $${\text{NO}}^{ - }_{3} $$ are 330 and 480 mg m−2 y−1, respectively, in contrast to their corresponding dry-deposition fluxes (14 and 160 mg m−2 y−1); whereas wet and dry removal of Ca2+, Mg2+ and $${\text{SO}}^{{2 - }}_{4} $$ are comparable. [ABSTRACT FROM AUTHOR]

Presents information on a study that measured the distribution of polonium-210 and lead-210 in the dissolved and total phase of sea water samples in the upper 500 meters at four stations along a western transect in the South-equitorial Atlantic. Sampling and analytical methods; Results and discussion; Conclusion of the study.

The chemical composition of aerosols in the Marine Atmospheric Boundary Layer (MABL) of Bay of Bengal (BoB) and Arabian Sea (AS) has been studied during the spring and inter-monsoon (March-May 2006) based on the analysis of water soluble constituents (Na+, NH+ 4, K+, Mg2+, Ca2+, Cl-, NO-3 and SO2- 4 ), crustal elements (Al, Fe, and Ca) and carbonaceous species (EC, OC). The total suspended particulates (TSP) ranged from 5.2 to 46.6 μg m-3 and 8.2 to 46.9 μg m-3 during the sampling transects in the BoB and AS respectively. The water-soluble species, on average, accounted for 44% and 33% of TSP over BoB and AS respectively, with dominant contribution of SO2-4 over both the oceanic regions. However, distinct differences with respect to elevated abundances of NH+ 4 in the MABL of BoB and that of Na+ and Ca2+ in AS are clearly evident. The non-sea-salt component of SO2- 4 ranging from 82 to 98% over BoB and 35 to 98% over AS; together with nss-Ca2+/nss-SO2- 4 equivalent ratios 0.12 to 0.5 and 0.2 to 1.16, respectively, provide evidence for the predominance of anthropogenic constituents and chemical transformation processes occurring within MABL. The concentrations of OC and EC average around 1.9 and 0.4 μg m-3 in BoB and exhibit a decreasing trend from north to south; however, abundance of these carbonaceous species are not significantly pronounced over AS. The abundance of Al, used as a proxy for mineral aerosols, varied from 0.2 to 1.9 μg m-3 over BoB and AS, with a distinctly different spatial pattern - decreasing north to south in BoB in contrast to an increasing pattern in the Arabian Sea. [ABSTRACT FROM AUTHOR]

The problem of growth rate and life span of Nummulites foraminifers, attaining giant sizes during the Eocene, has been addressed by analysing their Sr/Ca ratio across the Eocene/Oligocene Boundary (EOB) of Kutch, western India. The Eocene ratio ( 1) rapidly decreases during the Oligocene ( 0.5) and is coincident with the extinction of most of the Eocene Nummulites species, a rapid enrichment of δ18O and decrease in both test size and species diversity across the boundary. The high Sr/Ca ratio in Eocene foraminifers can be explained by their rapid growth under a favourable climatic condition. The climatic deterioration (e.g. δ18O cooling) across the boundary and during the early Oligocene possibly forced the Nummulites to adopt a slower growth rate (and stunted growth). The rapid growth of the Eocene Nummulites indicates that the giant sizes of these protists need not necessarily involve a large life span. [ABSTRACT FROM AUTHOR]

The article offers information on the primary characteristics of aerosols. It notes that direct sources of aerosols include world oceans, arid and semi-arid regions, terrestrial biota and smoke from forest fires. However, researchers suggests to note that EC warms the atmosphere while OC cools and their radiative effects depend on the emission source.

We compare the mass concentrations of black carbon (BC) and elemental carbon (EC) from different emissions in the Indo-Gangetic Plain (IGP), using optical (Aethalometer; 880 nm) and thermooptical technique (EC-OC analyzer; 678 nm), respectively. The fractional contribution of BC mass concentration measured at two different channels (370 and 880 nm), OC/EC ratio, and non-sea-salt K+/EC ratios have been systematically monitored for representing the source characteristics of BC and EC in this study. The mass concentrations of BC varied from 8.5 to 19.6,2.4 to 18.2, and 2.2 to 9.4 μg m-3 during October-November (paddy-residue burning emission), December-March (emission from bio- and fossil-fuel combustion) and April-May (wheat-residue burning emission), respectively. In contrast, the mass concentrations of EC varied from 3.8 to 17.5, 2.3 to 8.9, and 2.0 to 8.8 μg m-3 during these emissions, respectively. The BC/EC ratios conspicuously greater than 1.0 have been observed during paddy-residue burning emissions associated with high mass concentrations of EC, OC, and OC/EC ratio. The ¿Angström exponent (α) derived from Aethalometer data is approximately 1.5 for the postharvest agricultural-waste burning emissions, hitherto unknown for the IGP. The mass absorption efficiency (MAE) of BC and EC centers at ~1-4 m² g-1 and 2-3 m² g-1 during the entire study period in the IGP. [ABSTRACT FROM AUTHOR]

A 38-year-old female presented with hyperpigmented velvety plaques on the nape and the sides of the neck with diffuse pigmentation of the face and flexures suggestive of acanthosis nigricans. The dorsa of both the hands showed increased rugosity, hyperpigmentation and hyperkeratosis of the palms, suggestive of tripe palms. Investigations revealed multiple secondaries in the liver. Histopathology showed the secondaries to be from adenocarcinoma of the gastrointestinal tract. [ABSTRACT FROM AUTHOR]