Biogeochemistry of light hydrocarbons in south Florida wetlands

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5581977

Barber, T R

Light hydrocarbons are ubiquitous in south Florida wetlands. Natural processes of enrichment or depletion of dissolved light hydrocarbons include: air/water exchange, seepage and diffusion across the sediment/water interface, advective transport, microbial consumption during migration, and in situ biological and photochemical production. Anthropogenic inputs result from offshore and onshore oil and natural gas production, manufacturing, and transportation operations. The mean diffusive flux of light hydrocarbons from 5 freshwater lakes was 12.4 g CH[sub 4]/m[sup 2]/yr. The mean diffusive flux for an urbanized, sub-tropical estuary (Tampa Bay) was 0.96 g CH[sub 4]/m[sup 2]/yr. The diffusive methane flux from the Everglades sawgrass marsh system ranged from 2.89 g CH[sub 4]/m[sup 2]/yr for densely vegetated regions to 32.3 g CH[sub 4]/m[sup 2]/yr for sparsely vegetated, carbonate-mud areas. A strong methane flux (30.0 g CH[sub 4]/m[sup 2]/yr) was estimated for an organic-rich brackish pond, near Florida Bay. The diffusive flux accounted for 15 to 35% of the total methane flux from these environments. The biogenic flux of ethane from several south Florida wetlands varied from 4.6 mg C[sub 2]H[sub 6]/m[sup 2]/yr from densely vegetated sawgrass marshes to 110 mg C[sub 2]H[sub 6]/m[sup 2]/yr from Tampa Bay. Ethane flux from estuarine environments was significantly larger than from freshwater sites. The annual biogenic ethane flux was estimated at 0.02 Tg (Tg = 10[sup 12] g). The contribution of natural wetlands to the global budget is relatively insignificant. Stable isotope data and the CH[sub 4]/C[sub 2]H[sub 6] ratio were used to evaluate the importance of methane oxidation in south Florida wetlands. Microbial oxidation reduces the diffusive methane flux from the Florida Everglades greater than 95%.

• Research Organization: University of South Florida, Tampa, FL (United States)
• OSTI ID: 5581977
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540220* -- Environment
Terrestrial-- Chemicals Monitoring & Transport-- (1990-)
560300 -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKANES
AQUATIC ECOSYSTEMS
BIODEGRADATION
BIOGEOCHEMISTRY
CHEMICAL REACTIONS
CHEMISTRY
CONTAMINATION
DECOMPOSITION
DEVELOPED COUNTRIES
DIFFUSION
ECOLOGICAL CONCENTRATION
ECOSYSTEMS
ENVIRONMENTAL TRANSPORT
FLORIDA
GEOCHEMISTRY
HYDROCARBONS
INDUSTRY
LAKES
MARSHES
MASS TRANSFER
METHANE
MIGRATION
NATURAL GAS INDUSTRY
NORTH AMERICA
ORGANIC COMPOUNDS
OXIDATION
PETROLEUM INDUSTRY
SURFACE WATERS
USA
WETLANDS