Atmospheric vs Biological sources of polycyclic aromatic hydrocarbons ( PAHs) in a tropical rain for...
Download
1 / 20

Author: Krauss et. Al Presentation : Prasesh Sharma - PowerPoint PPT Presentation


  • 108 Views
  • Uploaded on

Atmospheric vs Biological sources of polycyclic aromatic hydrocarbons ( PAHs) in a tropical rain forest. Author: Krauss et. Al Presentation : Prasesh Sharma. PAH (polyaromatic hydrocarbons). Larger systems of benzene ring structure fused together is called PAH

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Author: Krauss et. Al Presentation : Prasesh Sharma' - jake


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Atmospheric vs Biological sources of polycyclic aromatic hydrocarbons ( PAHs) in a tropical rain forest

Author: Krauss et. Al

Presentation : Prasesh Sharma


Pah polyaromatic hydrocarbons
PAH (polyaromatic hydrocarbons) hydrocarbons ( PAHs) in a tropical rain forest

Larger systems of benzene ring structure fused together is called PAH

Chemistry of the structures is the same but usually more reactive then benzene

Benzene

Anthracene

Naphthalene

Phenanthrene

Perylene


Sources of pahs
Sources of PAHs hydrocarbons ( PAHs) in a tropical rain forest

  • PAHs mainly arise from combustion-related or oil-related man-made sources.

    • burning of coal, oil, gas, wood, tobacco, rubbish, and other organic substances.

    • also present in coal tars, crude oil, and petroleum products such as asphalt.

  • ubiquitous environmental contaminants

  • natural sources : forest fires and volcanoes,


Effects of pah
Effects of PAH hydrocarbons ( PAHs) in a tropical rain forest

  • Short-term : irritation, nausea,

  • Long term : Carcinogenic

  • Reproductive failures

  • Kidney, liver damage, jaundice

  • Bioaccumulates rapidly in aquatic life


Introduction
Introduction hydrocarbons ( PAHs) in a tropical rain forest

  • PAH burden in temperate env– mostly pyrogenic

    • Burning of fossil fuels, coal, oil refining etc

  • Essential to understand and predict the global

    dynamics and trends of these compounds

  • Tropical rain forest : limited knowledge of its distribution

  • Recently, biological sources of PAHs have been known.


  • GENERAL INFORMATION hydrocarbons ( PAHs) in a tropical rain forest

    • Evidence of NAPH derived from its presence in Magnolia

    • NAPH produced by a muscodor vitigenus

      (endophytic fungus)

    • High concentration in termite nests- forms a part of the termite defensive system.

    • Comparision of 13C between termite nests and fossil fuel derived PERY : bio. production occurs in termite nests

    • Look for natural sources or PAHs production


    Objective
    Objective hydrocarbons ( PAHs) in a tropical rain forest

    • To monitor PAH concentration in different compartments of a tropical rain forest

    • Assess sources of PAHs ( atm.Vs bio.)

      by examining their distribution and relating PAHs concentrations in air to those in external plant parts.


    Study site
    Study site hydrocarbons ( PAHs) in a tropical rain forest

    • 30km north or Manaus, Brazil.

    • Lowland, tropical rain forest region mixed with fallow land, agricultural land and secondary forests.


    Sampling and analyses
    Sampling and analyses hydrocarbons ( PAHs) in a tropical rain forest

    • SAMPLING

      • Particulate and gaseous PAHs in air by membrane pump

      • Plant samples : stem, twigs, bark, leaves

      • Termite nests sampled : inner wall, outer wall, nursery and gallery

      • Soil samples, Litter layers : oil, dead leaves, dead plants, and other organisms collected on the ground

      • Samples were also taken in urban areas for comparision.

    • Plant samples from 1 primary and 3 secondary forests.

    • Analysis

      • PAHs extracted by Gas Chromatography and quantified with Mass Spectrometry


    Gas chromatography
    Gas Chromatography hydrocarbons ( PAHs) in a tropical rain forest

    For separation of volatile organic compounds


    Mass spectrometry
    Mass Spectrometry hydrocarbons ( PAHs) in a tropical rain forest


    Calculations
    Calculations hydrocarbons ( PAHs) in a tropical rain forest

    • Sum of all concentrations : ∑21 PAHs

    • 18 pyrogenic + 3 possibly biogenic (NAPH, PERY, PHEN)

    • Sum of 18 pyrogenic concn: ∑18 PAHs


    Results plants
    Results : Plants hydrocarbons ( PAHs) in a tropical rain forest

    • Highest concentration of PAHs in the following order

      • Leaves >bark > twigs > stem

  • ∑18PAHs follow same trend as ∑21PAHs, except NAPH

  • Biological production of PAHs assessed !

  • In case of PHEN : remarkably high concentrations in bark and twigs - > via biogenesis.


  • Results plant air distribution
    Results: Plant-air distribution hydrocarbons ( PAHs) in a tropical rain forest

    Octanol-air coef. = [K]octanol/[K]air

    Log KOA : octanol-air coefficient

    Log KLA : avge. concentration in air

    The octanol-air partition coefficient is a measure of chemical partitioning between the atmosphere and the organic matter in the environment.


    Results plant air distribution1
    Results: Plant-air distribution hydrocarbons ( PAHs) in a tropical rain forest

    • All PAHs plotted show plant-air distribution that fits well into the perception of PAH uptake by plants from air

    • Proof that source of most PAHs is the atmosphere.

    • However, NAPH behaves differently

    • NAPH – very high concentrations in plant tissue to that in air !!!

    • To reach those concentration levels by equilibrium partitioning => concentration of NAPH in air must be 50 times higher.


    Results mineral topsoil
    Results : Mineral Topsoil hydrocarbons ( PAHs) in a tropical rain forest

    • Fate of PAHs during organic matter transformation from litter to mineral soil acsessed

    • Enrichment factor of >1 in the topsoil compared to the litter layer.

    • PERY about 4 times than other compounds: microbial synthesis of PERY in soil !


    Results termite nests
    Results : Termite nests hydrocarbons ( PAHs) in a tropical rain forest

    Log KOWA ( outer wall-air ) vs Log KOA

    Regression line only for log KA < 7.5

    Similarity to earlier log plots


    Results termite nests1
    Results : Termite nests hydrocarbons ( PAHs) in a tropical rain forest

    • Nest is made up of : digested dead or living wood.

    • Concentration of 18PAHs higher in the outer wall and the gallery => pyrogenic deposition

    • Higher concentrations of NAPH than expected in outer wall and gallery … same case as in plant air distribution

    • Higher concentration of NAPH and PERY in central part of the termite nests.


    Conclusions
    Conclusions hydrocarbons ( PAHs) in a tropical rain forest

    • Naphthalene by far the most abundant PAH in the whole ecosystem

    • Most PAHs derived from biomass or fossil fuel combustion and is distributed in the atmosphere.

    • Numerous local biological sources of PAHs are present, more research is needed in the area !!!

    • Similarity in patterns to temperate regions


    References
    References hydrocarbons ( PAHs) in a tropical rain forest

    • Wilcke et.al 2003 , PAHs patterns in climatically different ecological zones of Brazil

    • http://www.atl.ec.gc.ca/epb/envfacts/pah.html

    • http://www.separationsnow.com/basehtml/SepH/1,,1-5-7-0-51405-ezine-0-2,00.html

    • http://oz.plymouth.edu/~chrisc/FishResBAFFM.htm

    • http://emsi.osu.edu/emsi_kids/PAH.htm


    ad