Sources and sinks of [sup 210]Pb in Concepcion Bay, Chile

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7285651

The sources and sinks of [sup 210]Pb to Concepcion Bay waters were evaluated to discern the relative importance of the main removal and supply mechanisms of this radionuclide to the waters of Concepcion Bay. The main inputs of [sup 210]Pb are the atmospheric supply and the advection of offshore upwelling waters. The atmospheric input was measured in precipitation using a collector and inventories of excess [sup 210]Pb in Rocuant and Raqui marsh sediments. The average atmospheric supply of [sup 210]Pb for Concepcion area is about 0.3 dpm cm[sup [minus]2] yr[sup [minus]1]. The advective input from upwelling varies from 0.6 [+-] 1.3 to 2.1 [+-] 2.0 dpm cm[sup [minus]2] yr[sup [minus]1]. [sup 210]Pb is removed efficiently from the water column as shelf water with high [sup 210]Pb content crosses the continental shelf off Concepcion Bay, with [sup 210]Pb/[sup 226]Ra activity ratios decreasing by a factor of 3 to 4 before reaching the interior of the bay. This is coincident with an increase of suspended matter concentration towards inside the bay. The main removal of [sup 210]Pb from Concepcion Bay waters is deposition in sediments. There is an increase of the [sup 210]Pb inventories toward the bay entrance excess (by a factor of 2) and outside the bay sediments (by a factor of 7). This pattern can be explained by an increase of mixing of sediments by the benthic infauna and enhanced removal of [sup 210]Pb from the water column by particles near the bay mouth. Mass balance calculations are included. The residence time of [sup 210]Pb with respect to removal from water column is estimated to be 17 to 43 days. The results of this research indicate that [sup 210]Pb and probably other similar particle-reactive contaminants (such as heavy metals) are retained and redistributed inside the bay by circulation, resuspension and biological mixing.

• Research Organization: State Univ. of New York, Stony Brook, NY (United States)
• OSTI ID: 7285651
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540330* -- Environment
Aquatic-- Radioactive Materials Monitoring & Transport-- (1990-)
AIR POLLUTION
ALPHA DECAY RADIOISOTOPES
BAYS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHILE
COASTAL WATERS
DEPOSITION
DEVELOPING COUNTRIES
ECOLOGICAL CONCENTRATION
EVEN-EVEN NUCLEI
HEAVY NUCLEI
ISOTOPES
LATIN AMERICA
LEAD 210
LEAD ISOTOPES
NUCLEI
POLLUTION
RADIOISOTOPES
SOUTH AMERICA
SURFACE WATERS
YEARS LIVING RADIOISOTOPES