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VOC Emissions (voc + emission)

Distribution by Scientific Domains

Life Sciences	55%

Selected Abstracts

Physico-Mechanical Properties, Odor and VOC Emission of Bio-Flour-Filled Poly(propylene) Bio-Composites with Different Volcanic Pozzolan Contents

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006
Hee-Soo Kim
Abstract Summary: This study investigated the physico-mechanical properties, odor and VOC emission of bio-flour filled PP bio-composites with different pozzolan contents. On increasing the pozzolan content, the tensile and flexural strengths of the bio-composites were not significantly changed, whereas the impact strength and water absorption increased slightly and the odor intensity decreased due to the absorption of thermal degradation gases of PP and bio-flour at the pore surface of the pozzolan. The VOC emission of the bio-composites, analyzed by GC-MSD, was mainly due to PP oxidation and the thermal degradation of bio-flour during the extrusion process at high manufacturing temperatures. With increased pozzolan content, other organic compounds of the bio-composites were not significantly changed, but the toluene emission of the bio-composites was decreased. SEM and SEM/EDX mapping techniques were employed to investigate the porous form and the pozzolan distribution in the bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was an effective method for reducing their odor and VOC emission without any reduction in mechanical properties. SEM micrograph of pozzolan (10,000×). [source]

Effect of arbuscular mycorrhizal (AM) colonization on terpene emission and content of Artemisia annua L.

PLANT BIOLOGY, Issue 1 2008
F. Rapparini
Abstract Plant roots interact with a wide variety of rhizospheric microorganisms, including bacteria and the symbiontic arbuscular mycorrhizal (AM) fungi. The mycorrhizal symbiosis represents a series of complex feedbacks between plant and fungus regulated by their physiology and nutrition. Despite the widespread distribution and ecological significance of AM symbiosis, little is known about the potential of AM fungi to affect plant VOC metabolism. The purpose of this study was to investigate whether colonization of plant roots by AM fungi and associated soil microorganisms affects VOC emission and content of Artemisia annua L. plants (Asteraceae). Two inoculum types were evaluated: one consisted of only an arbuscular mycorrhizal (AM) fungus species (Glomus spp.), and the other was a mixture of different Glomus species and associated soil bacteria. Inoculated plants were compared with non-inoculated plants and with plants supplemented with extra phosphorus (P) to obtain plants of the same size as mycorrhizal plants, thus excluding potentially-confounding mycorrhizal effects on shoot growth. VOC emissions of Artemisia annua plants were analyzed by leaf cuvette sampling followed by off-line measurements with pre-concentration and gas chromatography mass spectrometry (GC-MS). Measurements of CO2 and H2O exchanges were conducted simultaneously. Several volatile monoterpenes were identified and characterized from leaf emissions of Artemisia annua L. by GC-MS analysis. The main components identified belong to different monoterpene structures: ,-pinene, ,-pinene, camphor, 1,8-cineole, limonene, and artemisia ketone. A good correlation between monoterpene leaf concentration and leaf emission was found. Leaf extracts included also several sesquiterpenes. Total terpene content and emission was not affected by AM inoculation with or without bacteria, while emission of limonene and artemisia ketone was stimulated by this treatment. No differences were found among treatments for single monoterpene content, while accumulation of specific sesquiterpenes in leaves was altered in mycorrhizal plants compared to control plants. Growth conditions seemed to have mainly contributed to the outcome of the symbiosis and influenced the magnitude of the plant response. These results highlight the importance of considering the below-ground interaction between plant and soil for estimating VOC emission rates and their ecological role at multitrophic levels. [source]

Priming by airborne signals boosts direct and indirect resistance in maize

THE PLANT JOURNAL, Issue 1 2007
Jurriaan Ton
Summary Plants counteract attack by herbivorous insects using a variety of inducible defence mechanisms. The production of toxic proteins and metabolites that instantly affect the herbivore's development are examples of direct induced defence. In addition, plants may release mixtures of volatile organic compounds (VOCs) that indirectly protect the plant by attracting natural enemies of the herbivore. Recent studies suggest that these VOCs can also prime nearby plants for enhanced induction of defence upon future insect attack. However, evidence that this defence priming causes reduced vulnerability to insects is sparse. Here we present molecular, chemical and behavioural evidence that VOC-induced priming leads to improved direct and indirect resistance in maize. A differential hybridization screen for inducible genes upon attack by Spodoptera littoralis caterpillars identified 10 defence-related genes that are responsive to wounding, jasmonic acid (JA), or caterpillar regurgitant. Exposure to VOCs from caterpillar-infested plants did not activate these genes directly, but primed a subset of them for earlier and/or stronger induction upon subsequent defence elicitation. This priming for defence-related gene expression correlated with reduced caterpillar feeding and development. Furthermore, exposure to caterpillar-induced VOCs primed for enhanced emissions of aromatic and terpenoid compounds. At the peak of this VOC emission, primed plants were significantly more attractive to parasitic Cotesia marginiventris waSPS. This study shows that VOC-induced priming targets a specific subset of JA-inducible genes, and links these responses at the molecular level to enhanced levels of direct and indirect resistance against insect attack. [source]

Air pollution impedes plant-to-plant communication by volatiles

ECOLOGY LETTERS, Issue 9 2010
James D. Blande
Ecology Letters (2010) 13: 1172,1181 Abstract Volatile organic compounds (VOCs) emitted by damaged plants convey information to undamaged neighbouring plants, and previous research has shown that these signals are effective over short distances in nature. Many herbivore-induced VOCs react with ozone, which is the most important tropospheric air pollutant in rural areas. We used extrafloral nectar (EFN) secretion as a phenotypic indicator of between-plant communication in Phaseolus lunatus L. (Lima bean) and show that an ozone-rich (80 ppb) atmosphere reduces the distance over which signalling occurs. We found that ozone degrades several herbivore-induced VOCs, a likely mechanism reducing communication distances. Direct exposure to 80-ppb ozone did not affect the VOC emissions from P. lunatus. In addition, we demonstrated that high ozone concentrations, 120 and 160 ppb, induced EFN secretion in exposed plants, whereas more moderate concentrations, 80 and 100 ppb, did not. This suggests that ozone can play a complex role in the indirect defence of P. lunatus. [source]

Cryogenic condensation: A cost-effective technology for controlling VOC emissions

ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2002
Robert J. Davis
Cryogenic condensation is an extremely cost-effective technology for controlling emissions of Volatile Organic Compounds (VOCs) from chemical processing facilities under certain conditions. This paper describes the technology and provides the case history of an application in the pharmaceutical industry, in which its cost effectiveness was compared with a range of alternative technologies, including thermal oxidation, catalytic oxidation, flaring, carbon adsorption, and scrubbing. Because the facility already used significant quantities of liquid and gaseous nitrogen for inerting, blanketing, and purging, a very convenient cold source for cryogenic condensation was already present. On a lifetime cost basis, cryogenic condensation was significantly less costly than all other technologies evaluated. [source]

Monoterpene emissions from rubber trees (Hevea brasiliensis) in a changing landscape and climate: chemical speciation and environmental control

GLOBAL CHANGE BIOLOGY, Issue 11 2007
YONG-FENG WANG
Abstract Emissions of biogenic volatile organic compounds (VOCs) have important roles in ecophysiology and atmospheric chemistry at a wide range of spatial and temporal scales. Tropical regions are a major global source of VOC emissions and magnitude and chemical speciation of VOC emissions are highly plant-species specific. Therefore it is important to study emissions from dominant species in tropical regions undergoing large-scale land-use change, for example, rubber plantations in South East Asia. Rubber trees (Hevea brasiliensis) are strong emitters of light-dependent monoterpenes. Measurements of emissions from leaves were made in the dry season in February 2003 and at the beginning of the wet season in May 2005. Major emitted compounds were sabinene, , -pinene and , -pinene, but , -ocimene and linalool also contributed significantly at low temperature and light. Cis -ocimene was emitted with a circadian course independent of photosynthetic active radiation (PAR) and temperature changes with a maximum in the middle of the day. Total isoprenoid VOC emission potential at the beginning of the wet season (94 ,g gdw,1 h,1) was almost two orders of magnitude higher than measured in the dry season (2 ,g g dw,1 h,1). Composition of total emissions changed with increasing temperature or PAR ramps imposed throughout a day. As well as light and temperature, there was evidence that assimilation rate was also a factor contributing to seasonal regulating emission potential of monoterpenes from rubber trees. Results presented here contribute to a better understanding of an important source of biogenic VOC associated with land-use change in tropical South East Asia. [source]

Comparison of volatile emissions and structural changes of melt reprocessed polypropylene resins

ADVANCES IN POLYMER TECHNOLOGY, Issue 4 2002
Q. Xiang
Abstract Polypropylene (PP), as a commodity recyclable thermoplastic, was studied in this research to evaluate the potential environmental impact resulting from volatile organic compounds (VOCs) emitted during multiple melt reprocessing. Unstabilized PP (U-PP) and stabilized PP (S-PP) resins, simulating recycled materials prone to degradation, were evaluated for total VOC emissions generated during multiple melt reprocessing by injection molding and extrusion, respectively. Results show that the maximum amount of total VOCs from each cycle (up to six cycles for extrusion and up to ten for injection molding) did not significantly change, while the cumulative VOCs increased with increasing processing cycle for both materials. A good correlation between cumulative VOC increases and melt flow index increase for the U-PP and weight-average molecular weight Mw decrease for the S-PP were obtained. Reprocessing in all cases was accompanied by decreases in Mw and melt viscosity as a result of thermooxidative degradation. FTIR data considering increases in carbonyl content and degree of unsaturation suggest that at equivalent cycle numbers, degradation appears to be more severe for the extruded material in spite of the longer oxidative induction time of the "as received" pellets used in extrusion. The onset and type of structural changes are shown to depend on cycle number and reprocessing method. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 235,242, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10027 [source]