Triple Water Vapour–Isotopologues Record from Chhota Shigri, Western Himalaya, India: A Unified Interpretation based on δ17O, δ18O, δD and Comparison to Meteorological Parameters

The objective of this study is to investigate and understand the source and transportation of water vapour in the western Himalayan region—that is still missing—using water vapour stable isotopologues and air mass trajectory diagnostics. We report the first-time triple oxygen isotopic compositions of water vapour from high altitude western Himalaya (Chhota Shigri, India) and compare them with meteorological conditions at the site of investigation as well as tracked backwards through the Lagrangian air mass trajectory diagnostics. A total of 21 water vapour samples were collected using a quantitative cryogenic method. δ17O and δ18O values show a significant correlation coefficient of 0.999 (p <0.01). The temporal variations of δ17O, δ18O, δD, D-excess and 17O-excess are 1.2, 2.3, 17.3, 11.6 and 39‰ permeg, respectively. δ17O and δ18O exhibit significant (p < 0.05) diurnal variations along with meteorological parameters. Chhota Shigri vapour isotopic results show a clear difference in the 17O-excess value compared to near the south Indian Ocean and the Southern Ocean regions, reflecting the influence of local moisture recycling at the continental site. NCEP/NCAR reanalyses show lower Specific Humidity during the sampling period (September, ending month of the Indian summer monsoon) favouring evaporative conditions which are further corroborated through the Lagrangian moisture diagnostics suggesting frequent moisture uptake and moisture loss in specific regions.

Cultivable, halotolerant ice nucleating bacteria and fungi in coastal precipitation

Ice nucleating particles (INPs) are a rare subset of aerosol particles that initiate cloud droplet freezing at temperatures above the homogenous freezing point of water (−38 °C). Considering that the ocean covers 70 % of the earth's surface and represent a large potential source of INPs, it is imperative that the uncertainties in the identities and emissions of ocean INP become better understood. However, the specific underlying drivers of marine INP emissions and their identities remain largely unknown due to limited observations and the challenge involved in isolating exceptionally rare IN forming particles. By generating nascent sea spray aerosol (SSA) over a range of biological conditions, mesocosm studies show that microbes can contribute to marine INPs. Here, we identify 14 (30 %) cultivable halotolerant ice nucleating microbes and fungi among 47 total isolates recovered from precipitation and aerosol samples collected in coastal air in Southern California. IN isolates collected in coastal air were found to nucleate ice from extremely warm to moderate freezing temperatures (−2.3 to −18 °C). Air mass trajectory analyses, and cultivability in marine growth media indicate marine origins of these isolates. Further phylogenetic analysis confirmed that at least two of the 14 IN isolates were of marine origin. Moreover, results from cell washing experiments demonstrate that most IN isolates maintained freezing activity in the absence of nutrients and cell growth media. This study provides confirmation of previous studies' findings that implicated microbes as a potential source of marine INPs and additionally demonstrates links between precipitation, marine aerosol and IN microbes.

Advective Transport Modeling for Spatial Analysis of Atmospheric Aerosols over Lagos Area of South Western Nigeria

In this study atmospheric aerosols distribution over Lagos area of southwestern part of Nigeria was analyzed using backward air mass trajectory model. GPS information of the study region was used to simulate meteorological variables and aerosol data that have been stored by satellite imagery from the National Oceanography and Atmospheric Administration (NOAA) and Air Resource Laboratory (ARL). Hybrid Single-Particle Lagrangian Integrated Trajectories HYSPLIT was used to determine the wind-field information and also to obtain the backward air mass trajectory for atmospheric aerosols transport pattern at heights 0, 1000m and 2000m above ground level. The result showed that aerosols of sea-salt origin evolved from Atlantic ocean and spread over Lagos during the period under consideration. The average wind speed observed within the period ranged between 4 and 7m/s in south westerly direction which is attributed to the influence Atlantic Ocean. The results also showed that aerosol traversing Lagos area are mainly sea salts

The Relationship between Air-Mass Trajectories and the Abundance of Dust-Borne Prokaryotes at the SE Mediterranean Sea

Airborne prokaryotes are transported along with dust/aerosols, yet very little attention is given to their temporal variability above the oceans and the factors that govern their abundance. We analyzed the abundance of autotrophic (cyanobacteria) and heterotopic airborne microbes in 34 sampling events between 2015–2018 at a coastal site in the SE Mediterranean Sea. We show that airborne autotrophic (0.2–7.6 cells × 103 m−3) and heterotrophic (0.2–30.6 cells × 103 m−3) abundances were affected by the origin and air mass trajectory, and the concentration of dust/aerosols in the air, while seasonality was not coherent. The averaged ratio between heterotrophic and autotrophic prokaryotes in marine-dominated trajectories was ~1.7 ± 0.6, significantly lower than for terrestrial routes (6.8 ± 6.1). Airborne prokaryotic abundances were linearly and positively correlated to the concentrations of total aerosol, while negatively correlated with the aerosol’s anthropogenic fraction (using Pb/Al or Cu/Al ratios as proxies). While aerosols may play a major role in dispersing terrestrial and marine airborne microbes in the SE Mediterranean Sea, the mechanisms involved in the dispersal and diversity of airborne microorganisms remain to be studied and should include standardization in collection and analysis protocols.

Burning-derived vanillic acid in an Arctic ice core from Tunu, Northeastern Greenland

In this study, vanillic acid was measured in the Tunu ice core from northeastern Greenland in samples covering the past 1700 years. Vanillic acid is an aerosol-borne aromatic methoxy acid, produced by the combustion of lignin during biomass burning. Air mass trajectory analysis indicates that North American boreal forests are likely the major source region for biomass burning aerosols deposited to the ice core site. Vanillic acid levels in the Tunu ice core range from

THE CHARACTERISTICS AND POTENTIAL SOURCE AREA ANALYSIS OF PM_2.5 CONCENTRATION FOR ZHENGZHOU DURING 2016

This study used the HYSPLIT-4 model combined with cluster analysis, potential source pollution contribution functions and other methods to analyse the ground air pollution monitoring data and meteorological data in Zhengzhou during 2016. The results showed that: 1) the level of PM_2.5 reached the low value in summer. The PM_2.5 concentration reached the highest level in December and reached the lowest level in August. The daily variation characteristics of PM_2.5 concentration in different seasons were roughly the same, and it had an obviously "double-peak" structure. 2) The annual PM_2.5 concentration was positively correlated with atmospheric pressure and relative humidity. The annual PM_2.5 concentration was negatively correlated with temperature, visibility, precipitation, and wind speed. 3) In winter, the air mass trajectory that through the northern Sichuan – Gansu – Shaanxi – Hubei was polluted seriously, and the level of PM_2.5 was the highest which reached to 202.13 μg/m³. In summer, the air mass trajectory that came from Hubei was the lowest level with the value is 40.17 μg/m³. 4) The potential source areas located in northwest of Zhengzhou, Gansu, Hubei and Beijing-Tianjin-Hebei region in spring. The surrounding of Zhengzhou contributed to the pollution of Zhengzhou. The potential source areas appeared in Shaanxi, Sichuan, and Qinghai, the border between Ningxia and Inner Mongolia in autumn. In winter the potential source areas located in Jiangsu, Hubei, Henan, eastern of Shanxi, southern of Shanxi, Ningxia and the area of Yellow Sea, etc.