Seasonal variations in characteristics, sources and diurnal patterns of carbonaceous and water-soluble constituents in urban aerosols from the east coast of tropical India

2021 ◽  
Author(s):  
Suresh K. R. Boreddy ◽  
Prashant Hegde ◽  
A. R. Aswini ◽  
M. Ashok Williams ◽  
R. Elavarasi ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
East Coast ◽  
Water Soluble ◽  
Urban Aerosols ◽  
Diurnal Patterns

Seasonal variations of elemental carbon in urban aerosols as measured by two common thermal-optical carbon methods

2009 ◽  
Vol 407 (18) ◽  
pp. 5176-5183 ◽  
Author(s):  
Min-Suk Bae ◽  
James J. Schauer ◽  
Jay R. Turner ◽  
Philip K. Hopke
Keyword(s):  
Seasonal Variations ◽  
Elemental Carbon ◽  
Urban Aerosols

scholarly journals Current Understanding of the Driving Mechanisms for Spatiotemporal Variations of Atmospheric Speciated Mercury: A Critical Review

2016 ◽  
Author(s):  
Huiting Mao ◽  
Irene Cheng ◽  
Leiming Zhang
Keyword(s):  
Boundary Layer ◽  
Northern Hemisphere ◽  
Seasonal Variations ◽  
Seasonal Pattern ◽  
High Elevation ◽  
Future Research ◽  
Free Troposphere ◽  
Spatiotemporal Variations ◽  
Driving Mechanisms ◽  
Diurnal Patterns

Abstract. Understanding of spatial and temporal variations of atmospheric speciated mercury can advance our knowledge of mercury cycling in various environments. This review summarized spatiotemporal variations of total gaseous mercury or gaseous elemental mercury (TGM/GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM) in various environments including oceans, continents, high elevation, the free troposphere, and low to high latitudes. In the marine boundary layer (MBL), the oxidation of GEM was generally thought to drive the diurnal and seasonal variations of TGM/GEM and GOM in most oceanic regions, leading to lower GEM and higher GOM from noon to afternoon and higher GEM during winter and higher GOM during spring-summer. At continental sites, the driving mechanisms of TGM/GEM diurnal patterns included surface and local emissions, boundary layer dynamics, GEM oxidation, and mountain-valley winds at high elevation sites. Oxidation of GEM and entrainment of GOM from the free troposphere influenced the diurnal patterns of GOM at continental sites. No pronounced diurnal variation was found for Tekran measured PBM at MBL and continental sites. Seasonal variations in TGM/GEM at continental sites were attributed to increased winter combustion, increased surface emissions during summer, and monsoons in Asia. GEM oxidation, free tropospheric transport, anthropogenic emissions, and wet deposition appeared to affect the seasonal pattern of GOM at continental sites. Since measurements were predominantly in the northern hemisphere (NH), increased PBM at continental sites during winter was primarily due to local/regional coal combustion and wood burning emissions. Long-term TGM measurements from the MBL and continental sites indicated an overall declining trend consistent with those of anthropogenic and natural emissions and potentially redox chemistry. The latitudinal gradient in TGM/GEM showed an increase from the southern to northern hemisphere due largely to the vast majority of Hg emissions in the NH. This gradient was insignificant during summer probably as a result of weaker meridional mixing. Aircraft measurements indicated no significant GEM gradient with altitude over the field campaign regions; however depletion of GEM was observed in air masses under stratospheric influence. Remaining questions and issues related to factors potentially contributing to the observed spatiotemporal variations were identified, and recommendations for future research needs were provided.

Seasonal variations in UV-B absorbing capacity and allelopathic potential of Dittrichia viscosa leaf rinsates

1997 ◽  
Vol 75 (8) ◽  
pp. 1371-1374 ◽  
Author(s):  
M. Stephanou ◽  
Y. Manetas
Keyword(s):  
Seed Germination ◽  
Competitive Advantage ◽  
Key Words ◽  
Seasonal Variations ◽  
Water Soluble ◽  
Seasonal Fluctuations ◽  
Allelopathic Potential ◽  
Dittrichia Viscosa ◽  
The Mediterranean ◽  
Allelopathic Interference

The seasonal variations in the amount and the allelopathic potential of the water-soluble, leaf epicuticular exudates in the Mediterranean ruderal Dittrichia viscosa were investigated. Both parameters peaked during the dry, hot, and sunny summer, confirming the prediction that the seasonal fluctuations should be commensurate with the ascribed antitranspirant and phytotoxic functions. In particular, the drainage of the material to the soil with the heavy autumn rains provides excellent timing for exerting its strong allelopathic interference on seed germination, affording D. viscosa a considerable competitive advantage. Key words: allelopathy, Dittrichia viscosa, leaf rinsates, seasonal variations.

scholarly journals Diurnal Changes in Water Soluble Carbohydrate Components in Leaves and Sucrose Associated TaSUT1 Gene Expression during Grain Development in Wheat

2020 ◽  
Vol 21 (21) ◽  
pp. 8276
Author(s):  
Sarah Al-Sheikh Ahmed ◽  
Jingjuan Zhang ◽  
Hussein Farhan ◽  
Yingquan Zhang ◽  
Zitong Yu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Developmental Stages ◽  
Grain Filling ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Diurnal Changes ◽  
Flag Leaves ◽  
Diurnal Patterns ◽  
Carbohydrate Components ◽  
Water Soluble Carbohydrate

In plant tissues, sugar levels are determined by the balance between sugar import, export, and sugar synthesis. So far, water soluble carbohydrate (WSC) dynamics have not been investigated in a diurnal context in wheat stems as compared to the dynamics in flag leaves during the terminal phases of grain filling. Here, we filled this research gap and tested the hypothesis that WSC dynamics interlink with gene expression of TaSUT1. The main stems and flag leaves of two genotypes, Westonia and Kauz, were sampled at four hourly intervals over a 24 h period at six developmental stages from heading to 28 DAA (days after anthesis). The total levels of WSC and WSC components were measured, and TaSUT1 gene expression was quantified at 21 DAA. On average, the total WSC and fructan levels in the stems were double those in the flag leaves. In both cultivars, diurnal patterns in the total WSC and sucrose were detected in leaves across all developmental stages, but not for the fructans 6-kestose and bifurcose. However, in stems, diurnal patterns of the total WSC and fructan were only found at anthesis in Kauz. The different levels of WSC and WSC components between Westonia and Kauz are likely associated with leaf chlorophyll levels and fructan degradation, especially 6-kestose degradation. High correlation between levels of TaSUT1 expression and sucrose in leaves indicated that TaSUT1 expression is likely to be influenced by the level of sucrose in leaves, and the combination of high levels of TaSUT1 expression and sucrose in Kauz may contribute to its high grain yield under well-watered conditions.

scholarly journals Chemical characterisation of water-soluble ions in atmospheric particulate matter on the east coast of Peninsular Malaysia

2019 ◽  
Vol 19 (3) ◽  
pp. 1537-1553 ◽  
Author(s):  
Naomi J. Farren ◽  
Rachel E. Dunmore ◽  
Mohammed Iqbal Mead ◽  
Mohd Shahrul Mohd Nadzir ◽  
Azizan Abu Samah ◽  
...  
Keyword(s):  
South China Sea ◽  
East Asia ◽  
East Coast ◽  
Peninsular Malaysia ◽  
Water Soluble ◽  
Time Resolved ◽  
Air Masses ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Marine Air

Abstract. Air quality on the east coast of Peninsular Malaysia is influenced by local anthropogenic and biogenic emissions as well as marine air masses from the South China Sea and aged emissions transported from highly polluted East Asian regions during the winter monsoon season. An atmospheric observation tower has been constructed on this coastline at the Bachok Marine Research Station. Daily PM2.5 samples were collected from the top of the observation tower over a 3-week period, and ion chromatography was used to make time-resolved measurements of major atmospheric ions present in aerosol. SO42- was found to be the most dominant ion present and on average made up 66 % of the total ion content. Predictions of aerosol pH were made using the ISORROPIA II thermodynamic model, and it was estimated that the aerosol was highly acidic, with pH values ranging from −0.97 to 1.12. A clear difference in aerosol composition was found between continental air masses originating from industrialised regions of East Asia and marine air masses predominantly influenced by the South China Sea. For example, elevated SO42- concentrations and increased Cl− depletion were observed when continental air masses that had passed over highly industrialised regions of East Asia arrived at the measurement site. Correlation analyses of the ionic species and assessment of ratios between different ions provided an insight into common sources and formation pathways of key atmospheric ions, such as SO42-, NH4+ and C2O42-. To our knowledge, time-resolved measurements of water-soluble ions in PM2.5 are virtually non-existent in rural locations on the east coast of Peninsular Malaysia. Overall this dataset contributes towards a better understanding of atmospheric composition in the Maritime Continent, a region of the tropics that is vulnerable to the effects of poor air quality, largely as a result of rapid industrialisation in East Asia.

scholarly journals Chemical Characterisation of Water-soluble Ions in Atmospheric Particulate Matter on the East Coast of Peninsular Malaysia

2018 ◽  
Author(s):  
Naomi J. Farren ◽  
Rachel E. Dunmore ◽  
Mohammed Iqbal Mead ◽  
Mohd Shahrul Mohd Nadzir ◽  
Azizan Abu Samah ◽  
...  
Keyword(s):  
South China Sea ◽  
East Asia ◽  
East Coast ◽  
Peninsular Malaysia ◽  
Water Soluble ◽  
Time Resolved ◽  
Air Masses ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Marine Air

Abstract. Air quality on the east coast of Peninsular Malaysia is influenced by local anthropogenic and biogenic emissions, as well as marine air masses from the South China Sea and aged emissions transported from highly polluted East Asian regions during the winter monsoon season. An atmospheric observation tower has been constructed on this coastline at the Bachok Marine and Atmospheric Research Station. Daily PM2.5 samples were collected from the top of the observation tower over a 3-week period, and ion chromatography was used to make time-resolved measurements of major atmospheric ions present in aerosol. SO42− was found to be the most dominant ion present, and on average made up 66 % of the total ion content. Predictions of aerosol pH were made using the ISOROPPIA-II thermodynamic model and it was estimated that the aerosol was highly acidic, with pH values ranging from −0.97 to 1.12. A clear difference in aerosol composition was found between continental air masses originating from industrialised regions of East Asia and marine air masses predominantly influenced by the South China Sea. For example, elevated SO42− concentrations and increased Cl− depletion was observed when continental air masses that had passed over highly industrialised regions of East Asia arrived at the measurement site. Correlation analyses of the ionic species and assessment of ratios between different ions provided an insight into common sources and formation pathways of key atmospheric ions, such as SO42−, NH4+ and C2O42−. To our knowledge, time-resolved measurements of water-soluble ions in PM2.5 are virtually non-existent in rural locations on the east coast of Peninsular Malaysia; overall this dataset contributes towards a better understanding of atmospheric composition in the Maritime Continent, a region of the tropics that is vulnerable to the effects of poor air quality, largely as a result of rapid industrialisation in East Asia.

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