Ambient air characteristics of biogenic volatile organic compounds at a tropical evergreen forest site in Central Western Ghats of India

2021 ◽  
Author(s):  
Nidhi Tripathi ◽  
L. K. Sahu ◽  
Kashyap Patel ◽  
Ashwini Kumar ◽  
Ravi Yadav
Keyword(s):  
Organic Compounds ◽  
Western Ghats ◽  
Ambient Air ◽  
Evergreen Forest ◽  
Forest Site ◽  
Biogenic Volatile Organic Compounds ◽  
Tropical Evergreen Forest ◽  
Western Ghats Of India ◽  
Volatile Organic ◽  
Central Western Ghats

scholarly journals Diel and seasonal changes of biogenic volatile organic compounds within and above an Amazonian rainforest

2015 ◽  
Vol 15 (6) ◽  
pp. 3359-3378 ◽  
Author(s):  
A. M. Yáñez-Serrano ◽  
A. C. Nölscher ◽  
J. Williams ◽  
S. Wolff ◽  
E. Alves ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ambient Air ◽  
Dry Season ◽  
Solar Irradiation ◽  
Biogenic Volatile Organic Compounds ◽  
Wet Season ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Amazonian Rainforest

Abstract. The Amazonian rainforest is a large tropical ecosystem, which is one of the last pristine continental terrains. This ecosystem is ideally located for the study of diel and seasonal behaviour of biogenic volatile organic compounds (BVOCs) in the absence of local human interference. In this study, we report the first atmospheric BVOC measurements at the Amazonian Tall Tower Observatory (ATTO) site, located in central Amazonia. A quadrupole proton-transfer-reaction mass spectrometer (PTR-MS), with seven ambient air inlets, positioned from near ground to about 80 m (0.05, 0.5, 4, 24, 38, 53 and 79 m above the forest floor), was deployed for BVOC monitoring. We report diel and seasonal (February–March 2013 as wet season and September 2013 as dry season) ambient mixing ratios for isoprene, monoterpenes, isoprene oxidation products, acetaldehyde, acetone, methyl ethyl ketone (MEK), methanol and acetonitrile. Clear diel and seasonal patterns were observed for all compounds. In general, lower mixing ratios were observed during night, while maximum mixing ratios were observed during the wet season (February–March 2013), with the peak in solar irradiation at 12:00 LT (local time) and during the dry season (September 2013) with the peak in temperature at 16:00 LT. Isoprene and monoterpene mixing ratios were the highest within the canopy with a median of 7.6 and 1 ppb, respectively (interquartile range (IQR) of 6.1 and 0.38 ppb) during the dry season (at 24 m, from 12:00 to 15:00 LT). The increased contribution of oxygenated volatile organic compounds (OVOCs) above the canopy indicated a transition from dominating forest emissions during the wet season (when mixing ratios were higher than within the canopy), to a blend of biogenic emission, photochemical production and advection during the dry season when mixing ratios were higher above the canopy. Our observations suggest strong seasonal interactions between environmental (insolation, temperature) and biological (phenology) drivers of leaf BVOC emissions and atmospheric chemistry. Considerable differences in the magnitude of BVOC mixing ratios, as compared to other reports of Amazonian BVOC, demonstrate the need for long-term observations at different sites and more standardized measurement procedures, in order to better characterize the natural exchange of BVOCs between the Amazonian rainforest and the atmosphere.

scholarly journals OH reactivity and concentrations of Biogenic Volatile Organic Compounds in a Mediterranean forest of downy oak trees

2015 ◽  
Vol 15 (16) ◽  
pp. 22047-22095 ◽  
Author(s):  
N. Zannoni ◽  
V. Gros ◽  
M. Lanza ◽  
R. Sarda ◽  
B. Bonsang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Degradation Products ◽  
Ambient Air ◽  
Oxidation Products ◽  
Deciduous Tree ◽  
Forest Site ◽  
Mediterranean Forests ◽  
Oak Trees ◽  
Volatile Organic

Abstract. Understanding the processes between the biosphere and the atmosphere is challenged by the difficulty to determine with enough accuracy the composition of the atmosphere. Total OH reactivity, which is defined as the total loss of the hydroxyl radical in the atmosphere, has proved to be an excellent tool to identify indirectly the important reactive species in ambient air. High levels of unknown reactivity were found in several forests worldwide and were often higher than at urban sites. Such results demonstrated the importance of OH reactivity for characterizing two of the major unknowns currently present associated to forests: the set of primary emissions from the canopy to the atmosphere and biogenic compounds oxidation pathways. Previous studies also highlighted the need to quantify OH reactivity and missing OH reactivity at more forested sites. Our study presents results of a field experiment conducted during late spring 2014 at the forest site at the Observatoire de Haute Provence, OHP, France. The forest is mainly composed of downy oak trees, a deciduous tree species characteristic of the Mediterranean region. We deployed the Comparative Reactivity Method and a set of state-of-the-art techniques such as Proton Transfer Reaction-Mass Spectrometry and Gas Chromatography to measure the total OH reactivity, the concentration of volatile organic compounds and main atmospheric constituents at the site. We sampled the air masses at two heights: 2 m, i.e. inside the canopy, and 10 m, i.e. above the canopy, where the mean canopy height is 5 m. We found that the OH reactivity at the site mainly depended on the main primary biogenic species emitted by the forest, which was isoprene and to a lesser extent by its degradation products and long lived atmospheric compounds (up to 26 % during daytime). We determined that the daytime total measured reactivity equaled the calculated reactivity obtained from the concentrations of the compounds measured at the site. Hence, no significant missing reactivity is reported in this specific site, neither inside, nor above the canopy. However, during two nights we reported a missing fraction of OH reactivity up to 50 %, possibly due to unmeasured oxidation products. Our results confirm the weak intra canopy oxidation, already suggested in a previous study focused on isoprene fluxes. They also demonstrate how helpful can be the OH reactivity as a tool to clearly characterize the suite of species present in the atmosphere. We show that our result of reactivity is among the highest reported in forests worldwide and stress the importance to quantify OH reactivity at more and diverse Mediterranean forests.

Structure and floristic composition of a tropical evergreen forest in south-west India

1996 ◽  
Vol 12 (2) ◽  
pp. 191-214 ◽  
Author(s):  
Jean-Pierre Pascal ◽  
Raphael Pelissier
Keyword(s):  
Western Ghats ◽  
Basal Area ◽  
Floristic Composition ◽  
Evergreen Forest ◽  
Systematic Sampling ◽  
Importance Value Index ◽  
Importance Value ◽  
Tropical Evergreen Forest ◽  
Western Ghats Of India ◽  
The Western Ghats

ABSTRACTA permanent plot of 28 ha was established in a dense wet evergreen forest in the Western Ghats of India to study the functioning of the ecosystem. Since April 1990, 1981 trees of ≥30 cm gbh have been enumerated in a systematic sampling of five strips totalling 3.12 ha. This paper describes the main structural and floristic characteristics of the plot.The density (635 trees ≥30 cm gbh per hectare) and basal area (39.7 m2 ha−1) are high. Despite the high diversity (Simpson's D = 0.92 and Shannon's H' = 4.56), four species are distinctly, dominant in terms of an importance value index (relative density + relative basal area). Each of these four species occupies a different layer in the ecosystem: Humboldtia brunonis Wall. (Fabaceae) dominates the undergrowth, Myristica dactyloïdes Gaertn. (Myristicaceae) the intermediate strata, Valeria indica L. (Dipterocarpaceae) the higher canopy level and Dipterocarpus indicus Bedd. (Dipterocarpaceae) the emergents. This pronounced species hierarchy is one of the most important characteristics of the evergreen forests of the Western Ghats. The two dipterocarps account for 20.1% of the total number of trees and contribute 40.9% to the total basal area. This formation can, therefore, be considered as the westernmost lowland dipterocarp forest of Asia.Analysis of the spatial variations in the floristic composition and in the structure of the main species populations shows that two kinds of mature phases can be identified: where the topography is raised and gently sloping, the vertical structure of the stand is discontinuous, with Dipterocarpus indicus and Vateria indica forming an emergent layer above a dense undergrowth; on slopes, the stand is lower, vertically continuous and saturated with Valeria indica and Myristica dactyloïdes. The link between the structure of the stand and dynamic processes is discussed.

scholarly journals Diel and seasonal changes of Biogenic Volatile Organic Compounds within and above an Amazonian rainforest site

2014 ◽  
Vol 14 (21) ◽  
pp. 29159-29208 ◽  
Author(s):  
A. M. Yañez-Serrano ◽  
A. C. Nölscher ◽  
J. Williams ◽  
S. Wolff ◽  
E. Alves ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ambient Air ◽  
Dry Season ◽  
Solar Irradiation ◽  
Biogenic Volatile Organic Compounds ◽  
Wet Season ◽  
Mixing Ratios ◽  
Volatile Organic ◽  
Amazonian Rainforest

Abstract. The Amazonian rainforest is a large tropical ecosystem, and is one of the last pristine continental terrains. This ecosystem is ideally located for the study of diel and seasonal behaviour of Biogenic Volatile Organic Compounds (BVOC) in the absence of local human interference. In this study, we report the first atmospheric BVOC measurements at the Amazonian Tall Tower Observatory (ATTO) site, located in Central Amazonia. A quadrupole Proton Transfer Reaction Mass Spectrometer (PTR-MS) with 7 ambient air inlets, positioned from near the ground to about 80 m (0.05, 0.5, 4, 24, 38, 53 and 79 m above the forest floor), was deployed for BVOC monitoring. We report diel and seasonal (February/March 2013 and September 2013) ambient mixing ratios for isoprene, monoterpenes, methyl vinyl ketone (MVK) + methacrolein (MACR), acetaldehyde, acetone, methyl ethyl ketone (MEK), methanol and acetonitrile. Clear diel and seasonal patterns were observed for all compounds during the study. In general, lower mixing ratios were observed during night, while maximum mixing ratios were observed with the peak in solar irradiation at 12:00 LT during the wet season (February/March 2013), and with the peak in temperature at 16:00 LT during the dry season (September 2013). Isoprene mixing ratios were highest within the canopy with a median of 7.6 ppb and interquartile range (IQR) of 6.1 ppb (dry season at 24 m, from 12:00–15:00). Monoterpene mixing ratios were higher than previously reported for any Amazonian rainforest ecosystem (median 1 ppb, IQR 0.38 ppb during the dry season at 24 m from 15:00–18:00). Oxygenated Volatile Organic Compound (OVOC) patterns indicated a transition from dominating forest emissions during the wet season to a blend of biogenic emission, photochemical production, and advection during the dry season. This was inferred from the high mixing ratios found within the canopy, and those obtained above the canopy for the wet and dry season, respectively. Our observations reveal strong seasonal BVOC patterns and oxidation capacity, reflected in the different vertical profiles obtained between the dry and wet season, most likely driven by insolation, temperature and phenology. In addition, significant differences to other reports of Amazonian BVOC demonstrate the need for long-term observations and more standardized measurement procedures in order to better understand the natural exchange of BVOC between the Amazonian rainforest and the atmosphere.

scholarly journals Tethered balloon measurements of biogenic volatile organic compounds at a Boreal forest site

2003 ◽  
Vol 3 (5) ◽  
pp. 5357-5397
Author(s):  
C. Spirig ◽  
A. Guenther ◽  
J. P. Greenberg ◽  
P. Calanca ◽  
V. Tarvainen
Keyword(s):  
Volatile Organic Compounds ◽  
Boreal Forest ◽  
Organic Compounds ◽  
Mixed Layer ◽  
Particle Formation ◽  
Surface Fluxes ◽  
Forest Site ◽  
Emission Model ◽  
Biogenic Volatile Organic Compounds ◽  
Volatile Organic

Abstract. Measurements of biogenic volatile organic compounds (VOCs) were performed at Hyytiälä, a Boreal forest site in Southern Finland as part of the project OSOA (origin and formation of secondary organic aerosol) in August 2001. At this site, frequent formation of new particles has been observed and the role of biogenic VOCs in this process is still unclear. Tethered balloons served as platforms to collect VOC samples within the planetary boundary layer at heights up to 1.2 km above ground during daytime. Mean mixed layer concentrations of total monoterpenes varied between 10 and 170 pptv, with α-pinene, limonene and Δ3-carene as major compounds, isoprene was detected at levels of 2–35 pptv. A mixed layer gradient technique and a budget approach are applied to derive surface fluxes representative for areas of tens to hundreds of square kilometres. Effects of spatial heterogeneity in surface emissions are examined with a footprint analysis. Depending on the source area considered, mean afternoon emissions of the sum of terpenes range between 180 and 300 μg m−2 h−1 for the period of 2 to 12 August 2001. Surface fluxes close to Hyytiälä were higher than the regional average, and agree well with mean emissions predicted by a biogenic VOC emission model. Total rates of monoterpene oxidation were calculated with a photochemical model. The rates did not correlate with the occurrence of new particle formation, but the ozone pathway was of more importance on days with particle formation. Condensable vapour production from the oxidation of monoterpenes throughout the mixed layer can only account for a fraction of the increase in aerosol mass observed at the surface.

scholarly journals Tethered balloon measurements of biogenic volatile organic compounds at a Boreal forest site

2004 ◽  
Vol 4 (1) ◽  
pp. 215-229 ◽  
Author(s):  
C. Spirig ◽  
A. Guenther ◽  
J. P. Greenberg ◽  
P. Calanca ◽  
V. Tarvainen
Keyword(s):  
Volatile Organic Compounds ◽  
Boreal Forest ◽  
Organic Compounds ◽  
Mixed Layer ◽  
Particle Formation ◽  
Surface Fluxes ◽  
Forest Site ◽  
Emission Model ◽  
Biogenic Volatile Organic Compounds ◽  
Volatile Organic

Abstract. Measurements of biogenic volatile organic compounds (VOCs) were performed at Hyytiälä, a Boreal forest site in Southern Finland as part of the OSOA (origin and formation of secondary organic aerosol) project in August 2001. At this site, frequent formation of new particles has been observed and the role of biogenic VOCs in this process is still unclear. Tethered balloons served as platforms to collect VOC samples within the planetary boundary layer at heights up to 1.2 km above ground during daytime. Mean mixed layer concentrations of total monoterpenes varied between 10 and 170 pptv, with a-pinene, limonene and D3-carene as major compounds, isoprene was detected at levels of 2-35 pptv. A mixed layer gradient technique and a budget approach are applied to derive surface fluxes representative for areas of tens to hundreds of square kilometres. Effects of spatial heterogeneity in surface emissions are examined with a footprint analysis. Depending on the source area considered, mean afternoon emissions of the sum of terpenes range between 180 and 300 mg m-2 h-1 for the period of 2-12 August 2001. Surface fluxes close to Hyytiälä were higher than the regional average, and agree well with mean emissions predicted by a biogenic VOC emission model. Total rates of monoterpene oxidation were calculated with a photochemical model. The rates did not correlate with the occurrence of new particle formation, but the ozone pathway was of more importance on days with particle formation. Condensable vapour production from the oxidation of monoterpenes throughout the mixed layer can only account for a fraction of the increase in aerosol mass observed at the surface.

Sign in / Sign up

Export Citation Format

Share Document