Marine biogeochemistry of mercury

Thesis/Dissertation · Wed Jan 01 00:00:00 EST 1986

OSTI ID:6621611

Gill, G A

Noncontaminating sample collection and handling procedures and accurate and sensitive analysis methods were developed to measure sub-picomolar Hg concentrations in seawater. Reliable and diagnostic oceanographic Hg distributions were obtained, permitting major processes governing the marine biogeochemistry of Hg to be identified. Mercury concentrations in the northwest Atlantic, central Pacific, southeast Pacific, and Tasman Sea ranged from 0.5 to 12 pM. Vertical Hg distributions often exhibited a maximum within or near the main thermocline. At similar depths, Hg concentrations in the northwest Atlantic Ocean were elevated compared to the N. Pacific Ocean. This pattern appears to result from a combination of enhanced supply of Hg to the northwest Atlantic by rainfall and scavenging removal along deep water circulation pathways. These observations are supported by geochemical steady-state box modelling which predicts a relatively short mean residence time for Hg in the oceans; demonstrating the reactive nature of Hg in seawater and precluding significant involvement in nutrient-type recyclic. Evidence for the rapid removal of Hg from seawater was obtained at two locations. Surface seawater Hg measurements along 160/sup 0/ W (20/sup 0/N to 20/sup 0/S) showed a depression in the equatorial upwelling area which correlated well with the transect region exhibiting low /sup 234/Th//sup 238/U activity ratios. This relationship implies that Hg will be scavenged and removed from surface seawater in biologically productive oceanic zones. Further, a broad minimum in the vertical distribution of Hg was observed to coincide with the intense oxygen minimum zone in the water column in coastal waters off Peru.

• Research Organization: Connecticut Univ., Storrs (USA)
• OSTI ID: 6621611
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
MERCURY COMPOUNDS
BIOGEOCHEMISTRY
SEAWATER
ISOTOPE RATIO
AQUATIC ECOSYSTEMS
ATLANTIC OCEAN
PACIFIC OCEAN
SPATIAL DISTRIBUTION
THORIUM 234
URANIUM 238
WATER CHEMISTRY
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
ECOSYSTEMS
EVEN-EVEN NUCLEI
GEOCHEMISTRY
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
SEAS
SURFACE WATERS
THORIUM ISOTOPES
URANIUM ISOTOPES
WATER
YEARS LIVING RADIOISOTOPES
520101* - Environment
Aquatic- Basic Studies- Radiometric Techniques- (-1989)