Detection of Fukushima Daiichi nuclear power plant accident radioactive traces in Monaco

Daily air monitoring of radionuclides in the Principality of Monaco (43 degrees 73'N, 7 degrees 43'E) after the Fukushima Daiichi nuclear power plant accident showed that only Iodine-131 (I-131) and Caesium isotopes (Cs-134 and Cs-137) were detected. The peak of I-131 varied and reached its maximum between March 29th and April 5th, meanwhile both peaks of Cs-134 and Cs-137 arrived later and attained a maximum between April 1st and 4th. Their maximum activity concentrations in air were 354, 30, and 37 mu Bq m(-3) respectively. The Cs-134 to Cs-137 activity ratio was close to 1, which is different from that one observed after the Chernobyl accident (around 0.54). Up to 95% of caesium isotopes were washed out by wet scavenging during 27-28th of March, where the maximum deposition rates of Cs-134 and Cs-137 (13.7 and 19.1 mBq m(-2) day(-1), respectively) were observed. The significant input of Cs-134 and Cs-137 into the Mediterranean seawater column (30 m depth) was detected later, on the 24th of May. Radioisotopes of caesium and iodine were found far above the applied detection limits, but still with no concern for harmful radiation exposure and public health. The contamination gradually decreased in air and activity concentrations returned to background values after one or two months. (C) 2012 Elsevier Ltd. All rights reserved.