Spatialvariabilityandthefateofcesiumincoastal….pdfVIP

Biogeosciences, 11, 5123–5137, 2014 /11/5123/2014/ doi:10.5194/bg-11-5123-2014 © Author(s) 2014. CC Attribution 3.0 License. Spatial variability and the fate of cesium in coastal sediments near Fukushima, Japan E. E. Black and K. O. Buesseler Woods Hole Oceanographic Institution, 266 Woods Hole Road, Mail Stop #25, Woods Hole, MA 02543-1050, USA Correspondence to: E. E. Black (eblack@) and K. O. Buesseler (kbuesseler@) Received: 12 February 2014 – Published in Biogeosciences Discuss.: 20 May 2014 Revised: 8 August 2014 – Accepted: 21 August 2014 – Published: 23 September 2014 Abstract. Quantifying the amount of cesium incorporated (Aoyama et al., 2012). While later reports indicate additional into marine sediments as a result of the Fukushima Dai-ichi releases to the ocean (TEPCO, 2014; Kanda, 2013), the ini- Nuclear Power Plant (FDNPP) accident has proven challeng- tial 137Cs activities measured in the FDNPP discharge chan- ing due to the limited multi-core sampling from within the nel from March to May of 2011 represent the most significant 30 km zone around the facility; the inherent spatial hetero- oceanic contribution to date, peaking at 68 million Bq m−3 geneities in ocean sediments; and the potential for inventory on 6 April 2011 (Buesseler et al., 2011). 137Cs emerged as fluctuations due to physical, biological, and chemical pro- the major oceanic contaminant, warranting long-term study cesses. Using 210Pb, 234 Th, 137Cs, and 134Cs profiles from 20 due to its ∼ 30 yr half-life and large release, generally esti- sediment cores, coastal sediment inventories were reevalu- mated to be around 15–30 PBq (Buesseler, 2014; Charette et ated. A 137Cs sediment inventory of 100 ± 50 TBq was found al., 2013; Povinec et al., 2013; Chino et al., 2011; Stohl et al., for an area of 55 000 km2 using cores from this study and 2011). 137C