234Th:238U disequilibrium as an indicator of sediment resuspension in Thermaikos Gulf, northwestern Aegean Sea

Muir, G.K.P. , Pates, J.M., Karageorgis, A.P. and Kaberi, H. (2005) 234Th:238U disequilibrium as an indicator of sediment resuspension in Thermaikos Gulf, northwestern Aegean Sea. Continental Shelf Research, 25(19-20), pp. 2476-2490. (doi: 10.1016/j.csr.2005.08.009)

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Abstract

<sup>234</sup>Th:<sup>238</sup>U disequilibria have been used extensively as tracers of particle dynamics in marine environments. <sup>234</sup>Th (t1/2=24.1 days) can be used as “proxy” for particle reactive pollutants, due to their similar rapid rate of scavenging onto particles and subsequent removal from the water column, to the sediments. Radioactive disequilibrium can be exploited to determine the rates and time-scales of processes occurring over days to months; in this instance the residence times of dissolved and particulate species with the benthic nepheloid layer (BNL). Three sampling cruises were undertaken in Thermaikos Gulf (NW Aegean Sea) during contrasting periods, to examine the impact of natural and anthropogenic activity on sediment resuspension. September and October 2001 represented background and trawling periods, respectively; January 2002 represented a mixed period, of trawling and storms. Dissolved <sup>234</sup>Th is scavenged actively at the BNL, in the presence of suspended particulate material (SPM), with a mean residence time of 16 days. There is a weak inverse correlation between dissolved <sup>234</sup>Th residence time and SPM concentration in the BNL, with the shortest residence times occurring during October 2001. No relationship was observed between particulate <sup>234</sup>Th activities and SPM concentrations, indicating that particles are rapidly removed from the system, either by sinking or advection. The mean particulate <sup>234</sup>Th residence time is 5 days.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Muir, Dr Graham
Authors: Muir, G.K.P., Pates, J.M., Karageorgis, A.P., and Kaberi, H.
Subjects:G Geography. Anthropology. Recreation > GE Environmental Sciences
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Continental Shelf Research
ISSN:0278-4343
Published Online:03 October 2005

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