Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component ...of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.
A new non-invasive and potentially inexpensive frontier in the diagnosis of cancer relies on the detection of volatile organic compounds (VOCs) in exhaled breath samples. Breath can be sampled and ...analyzed in real-time, leading to fascinating and cost-effective clinical diagnostic procedures. Nevertheless, breath analysis is a very young field of research and faces challenges, mainly because the biochemical mechanisms behind the cancer-related VOCs are largely unknown. In this review, we present a list of 115 validated cancer-related VOCs published in the literature during the past decade, and classify them with respect to their "fat-to-blood" and "blood-to-air" partition coefficients. These partition coefficients provide an estimation of the relative concentrations of VOCs in alveolar breath, in blood and in the fat compartments of the human body. Additionally, we try to clarify controversial issues concerning possible experimental malpractice in the field, and propose ways to translate the basic science results as well as the mechanistic understanding to tools (sensors) that could serve as point-of-care diagnostics of cancer. We end this review with a conclusion and a future perspective.
Breath tests cover the fraction of nitric oxide in expired gas (
), volatile organic compounds (VOCs), variables in exhaled breath condensate (EBC) and other measurements. For EBC and for
, official ...recommendations for standardised procedures are more than 10 years old and there is none for exhaled VOCs and particles. The aim of this document is to provide technical standards and recommendations for sample collection and analytic approaches and to highlight future research priorities in the field. For EBC and
, new developments and advances in technology have been evaluated in the current document. This report is not intended to provide clinical guidance on disease diagnosis and management.Clinicians and researchers with expertise in exhaled biomarkers were invited to participate. Published studies regarding methodology of breath tests were selected, discussed and evaluated in a consensus-based manner by the Task Force members.Recommendations for standardisation of sampling, analysing and reporting of data and suggestions for research to cover gaps in the evidence have been created and summarised.Application of breath biomarker measurement in a standardised manner will provide comparable results, thereby facilitating the potential use of these biomarkers in clinical practice.
Plants synthesize an amazing diversity of volatile organic compounds (VOCs) that facilitate interactions with their environment, from attracting pollinators and seed dispersers to protecting ...themselves from pathogens, parasites and herbivores. Recent progress in -omics technologies resulted in the isolation of genes encoding enzymes responsible for the biosynthesis of many volatiles and contributed to our understanding of regulatory mechanisms involved in VOC formation. In this review, we largely focus on the biosynthesis and regulation of plant volatiles, the involvement of floral volatiles in plant reproduction as well as their contribution to plant biodiversity and applications in agriculture via crop–pollinator interactions. In addition, metabolic engineering approaches for both the improvement of plant defense and pollinator attraction are discussed in light of methodological constraints and ecological complications that limit the transition of crops with modified volatile profiles from research laboratories to real-world implementation.
Decades of air quality improvements have substantially reduced the motor vehicle emissions of volatile organic compounds (VOCs). Today, volatile chemical products (VCPs) are responsible for half of ...the petrochemical VOCs emitted in major urban areas. We show that VCP emissions are ubiquitous in US and European cities and scale with population density. We report significant VCP emissions for New York City (NYC), including a monoterpene flux of 14.7 to 24.4 kg ⋅ d−1 ⋅ km−2 from fragranced VCPs and other anthropogenic sources, which is comparable to that of a summertime forest. Photochemical modeling of an extreme heat event, with ozone well in excess of US standards, illustrates the significant impact of VCPs on air quality. In the most populated regions of NYC, ozone was sensitive to anthropogenic VOCs (AVOCs), even in the presence of biogenic sources. Within this VOC-sensitive regime, AVOCs contributed upwards of ∼20 ppb to maximum 8-h average ozone. VCPs accounted for more than 50% of this total AVOC contribution. Emissions from fragranced VCPs, including personal care and cleaning products, account for at least 50% of the ozone attributed to VCPs. We show that model simulations of ozone depend foremost on the magnitude of VCP emissions and that the addition of oxygenated VCP chemistry impacts simulations of key atmospheric oxidation products. NYC is a case study for developed megacities, and the impacts of VCPs on local ozone are likely similar for other major urban regions across North America or Europe.
Tropospheric ozone (O3) is among the most damaging air pollutant to plants. Plants alter the atmospheric O3 concentration in two distinct ways: (i) by the emission of volatile organic compounds ...(VOCs) that are precursors of O3; and (ii) by dry deposition, which includes diffusion of O3 into vegetation through stomata and destruction by nonstomatal pathways. Isoprene, monoterpenes, and higher terpenoids are emitted by plants in quantities that alter tropospheric O3. Deposition of O3 into vegetation is related to stomatal conductance, leaf structural traits, and the detoxification capacity of the apoplast. The biochemical fate of O3 once it enters leaves and reacts with aqueous surfaces is largely unknown, but new techniques for the tracking and identification of initial products have the potential to open the black box.
Tropospheric ozone (O3) is one of the most widespread air pollutants and an important greenhouse gas that is detrimental to both human and plant health.Plant volatiles, such as isoprene, can increase O3 pollution in the troposphere through the formation of peroxy radicals, which react with nitric oxide to form O3.Other plant volatiles, such as monoterpenes, sesquiterpenes, and diterpenes, are stored in trichomes and once released can decrease O3 in the boundary layer and therefore reduce O3 flux into leaves.O3 can induce rapid stomatal closure to prevent the entry of O3 into the leaf and cause sluggish stomatal responses resulting in further O3 uptake and greater water loss.Better characterization of the radicals formed in leaves after O3 exposure would enable more accurate modeling of O3 deposition and improved strategies for O3 tolerance.
Volatile organic compounds (VOCs) emitted to the environment highly probably result in ecological and health risks. Many biotechnologies for waste gases containing hydrophobic VOCs have been ...developed in recent years. However, these biological processes usually exhibit poor removal performances for hydrophobic VOCs due to the low bioavailability. This review presents an overview of enhanced removal of hydrophobic VOCs in biofilters. Mechanisms and problems relevant to the biological removal of hydrophobic VOCs are reviewed, and then solutions including the addition of surfactants, application of fungal biocatalysts, biofiltration with pretreatment, innovative bioreactors and utilization of hydrophilic compounds are discussed in detail. Future research needs are also proposed. This review provides new insights into hydrophobic VOC removal by biofiltration.
Volatile terpenes – mediators of plant‐to‐plant communication Rosenkranz, Maaria; Chen, Yuanyuan; Zhu, Peiyuan ...
The Plant journal : for cell and molecular biology,
November 2021, 2021-11-00, 20211101, Letnik:
108, Številka:
3
Journal Article
Recenzirano
Odprti dostop
SUMMARY
Plants interact with other organisms employing volatile organic compounds (VOCs). The largest group of plant‐released VOCs are terpenes, comprised of isoprene, monoterpenes, and ...sesquiterpenes. Mono‐ and sesquiterpenes are well‐known communication compounds in plant–insect interactions, whereas the smallest, most commonly emitted terpene, isoprene, is rather assigned a function in combating abiotic stresses. Recently, it has become evident that different volatile terpenes also act as plant‐to‐plant signaling cues. Upon being perceived, specific volatile terpenes can sensitize distinct signaling pathways in receiver plant cells, which in turn trigger plant innate immune responses. This vastly extends the range of action of volatile terpenes, which not only protect plants from various biotic and abiotic stresses, but also convey information about environmental constraints within and between plants. As a result, plant–insect and plant–pathogen interactions, which are believed to influence each other through phytohormone crosstalk, are likely equally sensitive to reciprocal regulation via volatile terpene cues. Here, we review the current knowledge of terpenes as volatile semiochemicals and discuss why and how volatile terpenes make good signaling cues. We discuss how volatile terpenes may be perceived by plants, what are possible downstream signaling events in receiver plants, and how responses to different terpene cues might interact to orchestrate the net plant response to multiple stresses. Finally, we discuss how the signal can be further transmitted to the community level leading to a mutually beneficial community‐scale response or distinct signaling with near kin.
Significance Statement
Plants release a high diversity of various volatile terpene compounds that can function as intra‐ and interspecific chemical signals. In this review we discuss the current knowledge of different terpenes as plant‐to‐plant signaling cues, how the different cues may be perceived by plants, and how they may sensitize distinct signaling pathways in plant cells leading to improved immunity and fitness of plants and plant communities.
Volatile organic compounds (VOCs) are significant atmospheric pollutants that cause environmental and health risks. Waste gases polluted with multiple VOCs often need to be purified simultaneously in ...biofilters, which may lead to antagonistic, neutral, or synergistic effects on removal performance. Antagonism limits the application of biofilters to simultaneous treatment of multiple VOCs, while synergism has not yet been fully exploited. We review the interactions among multiple target pollutants and the changes in the bioavailability and biodegradability of substrates that are responsible for substrate interactions. Potential strategies for enhancing biofilter performance are then discussed. Finally, we propose further efforts to alleviate antagonism by enhancing bioavailability and biodegradability, and discuss possible challenges to take advantage of synergism.
The structure of microbial populations plays an important role in the interactions between hydrophobic and hydrophilic VOCs, and the application of specific single species or mixed microorganisms may alter substrate interactions and consequently enhance removal performance.
Enhancing the bioavailability of reluctant VOCs can better offset the negative interactions exerted by the cosubstrates.
Strategies to alleviate the negative interactions among multiple VOCs will make it possible to employ biofilters for full-scale removal of multiple VOCs.
Biofilter performance for hydrophobic VOCs can be enhanced by exploiting the synergistic interactions of hydrophilic substrates. Regulating operational parameters, such as changing the feeding loading rate for every component and alternating the use of some hydrophilic compounds, may be promising strategies.
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