Dissolved and particulate thorium 234 concentrations at time series station DYFAMED

DOI

234Th was used to quantify sinking fluxes and residence times of particles in surface waters of the north-western Mediterranean Sea. Measurements of dissolved and particulate 234Th were made at the DYFAMED station (43°25'N-7°51'E, JGOFS-France program). Sampling covered 1 year on four cruises in 1994 (February 9, April 29, June 3, October 1) and focused on a transition period in mid-spring with six repeated profiles collected during May 1995. 234Th was nearly in equilibrium with its parent 238U most of the year, except in spring. The intensive sampling in May shows a rapid evolution throughout the month from a moderate 234Th deficit to near-equilibrium values. The time-series of 234Th were treated with steady-state and non-steady-state models. 234Th particulate fluxes clearly indicate large variability in export, with the highest values observed in spring. Particle residence times in the upper 40 m range from 250 days, and could increase by a factor of 10 within 2 weeks. POC fluxes from the upper 40 m and export ratios (ThE: ratio of 234Th-derived POC export to primary production), derived from the 234Th/238U disequilibrium in the water column and POC/234Th ratio on trapped material, decrease from about 9.5 mmol C m-2 d-1 and >22% in early May to less than 5 mmol C m-2 d-1 and 15% after mid-May. The 234Th-derived information is in agreement with the annual variations in Mediterranean Sea productivity.

Supplement to: Schmidt, Sabine; Andersen, Valérie; Belviso, Sauveur; Marty, Jean-Claude (2002): Strong seasonality in particle dynamics of north-western Mediterranean surface waters as revealed by 234Th/238U. Deep Sea Research Part I: Oceanographic Research Papers, 49(8), 1507-1518

Identifier
DOI https://doi.org/10.1594/PANGAEA.737924
Related Identifier https://doi.org/10.1016/S0967-0637(02)00039-0
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.737924
Provenance
Creator Schmidt, Sabine ORCID logo; Andersen, Valérie; Belviso, Sauveur; Marty, Jean-Claude
Publisher PANGAEA
Publication Year 2002
Funding Reference European Commission https://doi.org/10.13039/501100000780 Crossref Funder ID ERBIC20-CT98-0103 Mediterranean Data Archaeology and Rescue; European Commission https://doi.org/10.13039/501100000780 Crossref Funder ID MAS3-CT98-0174 Mediterranean Data Archaeology and Rescue
Rights Creative Commons Attribution 3.0 Unported; https://creativecommons.org/licenses/by/3.0/
OpenAccess true
Representation
Language English
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 7 datasets
Discipline Ancient Cultures; Archaeology; Humanities
Spatial Coverage (7.252 LON, 43.428 LAT)
Temporal Coverage Begin 1995-05-03T00:00:00Z
Temporal Coverage End 1995-05-29T00:00:00Z