Abstract
Chloromethane (CH3Cl) is the most abundant halocarbon in the atmosphere. Although largely of natural origin it is responsible for
around 17% of chlorine-catalysed ozone destruction. Sources identified
to date include biomass burning, oceanic emissions, wood-rotting fungi,
higher plants and most recently tropical ferns. Current estimates
reveal a shortfall of around 2 million ty-(1) in sources versus sinks
for the halocarbon. It is possible that emissions from green plants
have been substantially underestimated. A potentially valuable tool for
validating emission flux estimates is comparison of the delta(13)C
value of atmospheric CH3Cl with those of CH3Cl from the various
sources. Here we report delta(13)C values for CH3Cl released by two
species of tropical ferns and show that the isotopic signature of CH3Cl
from pteridophytes like that of CH3Cl from higher plants is quite
different from that of CH3Cl produced by biomass burning, fungi and
industry. VC values for CH3Cl produced by Cyathea smithii and
Angiopteris evecta were respectively -72.7parts per thousand and
-69.3parts per thousand representing depletions relative to plant
biomass of 42.3parts per thousand and 43.4parts per thousand. The
characteristic isotopic signature of CH3Cl released by green plants
should help constrain their contribution to the atmospheric burden when
reliable delta(13)C values for all other major sources of CH3Cl are
obtained and a globally averaged delta(13)C value for atmospheric CH3Cl
is available. (C) 2003 Published by Elsevier Science Ltd.
| Original language | English |
|---|---|
| Pages (from-to) | 433-436 |
| Number of pages | 4 |
| Journal | Chemosphere |
| Volume | 52 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Jul 2003 |
Keywords
- tropical fern
- cyathea smithii
- angiopteris evecta
- carbon isotope ratio
- methyl chloride
- isotopic signature