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Compound specific isotope analysis in aerosol, paleo climatological and ecological research

English title Compound specific isotope analysis in aerosol, paleo climatological and ecological research
Applicant Siegwolf Rolf Theodor Walter
Number 128761
Funding scheme R'EQUIP
Research institution Labor für Atmosphärenchemie Paul Scherrer Institut
Institution of higher education Paul Scherrer Institute - PSI
Main discipline Climatology. Atmospherical Chemistry, Aeronomy
Start/End 01.03.2010 - 28.02.2011
Approved amount 400'000.00
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All Disciplines (2)

Discipline
Climatology. Atmospherical Chemistry, Aeronomy
Other disciplines of Environmental Sciences

Keywords (17)

compound specific isotope analysis; aerosols; paleo climatology; plant ecology; elevated CO2; secondary organic aerosols; process understanding; stable isotopes; stable C, O, N and H isotopes; Compound Specific Isotope Analysis (CSIA); Plants; Tree rings; Biogeochemistry; Ecosystem; Atmosphere; Environmental Science; Metabolism

Lay Summary (English)

Lead
Lay summary
Lead: The use of stable carbon, oxygen, hydrogen, and nitrogen isotopes has proven to be a highly versatile and powerful tool in environmental sciences. Depending on the physical chemical processes we find specific isotopic fingerprints, which help to understand the development of e.g. aerosols or the environmental impacts on various plant components. It also has the potential of source identification of various pollutants.Background: During the synthesis of various chemical compounds in the soil or atmosphere or during the formation of biological materials the heavier isotopes diffuse and react more slowly and form slightly stronger chemical bonds, which either leads to an enrichment (leaf water H218O) or depletion (13C during photosynthesis) of the heavier isotopes in the final product. Thus each of the different compounds show a very specific isotopic ratio between the heavier and lighter element, which is the result of chemical transformation processes. Usually whole leaves, aerosols or soil material is analyzed, which was mostly sufficient.Today, an increasing number of new results and an improved understanding of the biogeochemical and atmospheric processes demand for a more thorough explanation on a molecular level. Thus the next logical step is the compound specific isotope analysis (CSIA), allowing the separation, identification and the determination of its isotopic ratio. Therefore the isotope ratio in such specific compounds is key for identifying specific processes. This is instrumental for tracing the molecular flows and further a deepened understanding of the physical, chemical and biological mechanisms.Goal: The identification of such specific processes will help to understand the development of certain products (e.g. the formation of secondary organic aerosols) or changes in metabolic processes due to climatic impacts on the vegetation, which results in specific isotopic variations (e.g. in plant material like leaves or tree rings, the latter an important indicator for climate variations). This provides the basis for an improved understanding of the interactions between vegetation and atmosphere, like the exchange or formation of trace gases as a result of various metabolic processes.Significance: Analytical advances in the measurement of stable isotope ratios on individual organic compounds provide a new set of tools for ecology, ecosystem and atmospheric sciences where the molecular specificity and the isotopic signature of compounds can be explored concomitantly. The scope of applications is large and will provide new levels of process understanding for new mechanistic research directions in atmosphere and ecosystem sciences.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Associated projects

Number Title Start Funding scheme
111914 Swiss canopy crane (SCC): CO2-enrichment 01.04.2006 Project funding (Div. I-III)

Abstract

Summary With this proposal we request the matching funds to purchase the instrumentation for Compound Specific stable Isotope Analysis (CSIA). The CSIA allows the identification of processes and mechanisms, occur-ring in the formation of aerosols or atmospheric chemical reactions and in the interactions between vege-tation and atmosphere, like the exchange or formation of trace gases as a result of various metabolic processes. It also has the potential for source apportionment of various emissions, emitted into the at-mosphere and deposited into the vegetation. The use of stable isotopes has proven to be a highly versa-tile and powerful tool in the field of environmental sciences, focusing on the light elements like carbon (13C/12C), oxygen (18O/16O), hydrogen (2H/1H), and nitrogen (15N/14N) with their specific isotopic finger-prints in organic and inorganic material. The heavier isotopes diffuse and react more slowly during chemi-cal and biochemical transformations, which either lead to enrichment (leaf water H218O) or depletion (13C during photosynthesis) of chemical or biological products. Thus the ratio between the heavier and lighter isotopes can be related to fractionations occurring during specific processes, which helps to identify phys-icochemical or biochemical mechanisms. Usually bulk material (whole leaves, aerosols or soil material) is analyzed, which was in most cases sufficient. Today, however, an increasing number of new results and an improved understanding of the mechanisms of the biogeochemical and atmospheric chemical proc-esses demands for a more thorough explanation on the molecular level. The next logical step is the use of compound specific isotope analysis (CSIA). Analytical advances in the measurement of stable isotope ratios on individual organic compounds provide a new set of tools for ecology, ecosystem and atmos-pheric sciences where the molecular specificity and the isotopic signature of compounds can be explored concomitantly. The scope of applications is large and will provide new levels of process understanding for new mechanistic research directions in atmosphere and ecosystem sciences. With the proposed installation of a CSIA facility the following first objectives shall be addressed:1)Investigate the secondary organic aerosols (SOA) yield of small volatile compounds by the isotope labeling method, for different kind of compound classes like alkanes, alkenes, alcohols, which are emitted from traffic or as solvents. In a further step compound specific analysis will be used to deter-mine their oxidation products, which contribute to SOA. 2)It will be investigated to what extent small highly oxidized species (e.g. formaldehyde, glyoxal, meth-ylglyoxal, etc.) oligomerize forming low volatile species. 3)Investigate the isotopic signature of particle emissions from a diesel car and wood combustion and the fate of the primary particle emissions as they photochemically age. The goal is to use CSIA-IRMS as a tool for source apportionment of aerosols.4)Identify the carbohydrates, which are involved in respiration processes, and analyze the causes for a change in the isotopic ratio of the respiratory CO2; is it only a change in substrate consumption? To what degree is this change in d13C invoked by environmental parameters? The answer to these ques-tions will allow the modeling of the respiratory d13C variation, essential for understanding the net car-bon ecosystem exchange.5)There is evidence that elevated CO2 alters the composition of organic matter. This can lead to changes in the mineralization processes impacting the nutrient supply for the vegetation, with conse-quences for ecosystem productivity. With CSIA we will analyze the ratio of the photosynthates and their isotopic signature within plants, litter and soil. This information will help to estimate the degree of plant responses to environmental changes with respect to their specific compounds.6)Using CSIA will improve the climatic and environmental information extractable from tree-rings by analyzing other constituents of wood apart from cellulose, such as carbohydrates, lignin and its frag-ments. This will improve the reconstruction of past climate variability and environmental changes and help to disentangle anthropogenic impacts on forests for the last 150 years.The total costs for the CSIA instrumentation are 1’020 kFr. With this proposal we request 50% of these costs from the SNF R’Equip program, while the other 50% were requested from the PSI-reserves.
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