
TY  - JOUR
A1  - Cochran, JK 
A1  - Frignani, M 
A1  - Hirschberg, DJ 
A1  - Barnes, C 
T1  - Thorium isotopes as indicators of scavenging rates in the Venice Lagoon
JF  - Marine and Freshwater Research
JO  - Mar. Freshwater Res.
Y1  - 1995
VL  - 46
IS  - 1
SP  - 215
EP  - 221
KW  - 
UR  - https://doi.org/10.1071/MF9950215 
N2  - The naturally occurring thorium isotopes 228Th and 234Th, produced in sea water from decay of 228Ra and 238U, respectively, were used to estimate the rate of scavenging onto particle surfaces and the rate of removal of particles from the water column of the Venice Lagoon. Large water samples (1000-2000 L) were collected at three sites in the shallow (<1 m) waters of the lagoon. Samples were pumped through two 0.5-&#956;m wound filter cartridges to remove particles and then through two MnO2-impregnated cartridges to extract dissolved Th. Activities of particulate 234Th ranged from 510 to 1335 &#956;Bq L-1 and dissolved 234Th was <350 &#956;Bq L-1. Relative to calculated 238U activities in the lagoon, the 234Th data yielded mean residence times as short as 2 h for the scavenging of dissolved 234Th onto particles and 12 h for the removal of particulate 234Th. Resuspension rates of 0.6 to 8 mg cm-2 day-1 were estimated from the data on dissolved and particulate 234Th, these values being comparable to those determined by sediment traps (1.8-9.5 mg cm-2 day-1) at the same sites. These results suggest that Th and other similarly reactive trace metals are removed rapidly from the waters of the Venice Lagoon to the sediments. 
ER  -

