First retrieval of hourly atmospheric radionuclides just after the Fukushima accident by analyzing filter-tapes of operational air pollution monitoring stations

Abstract

No observed data have been found in the Fukushima Prefecture (FP) for the time-series of atmospheric radionuclides concentrations just after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident. Accordingly, current estimates of internal radiation doses from inhalation, and atmospheric radionuclide concentrations by atmospheric transport models are highly uncertain. Here, we present a new method for retrieving the hourly atmospheric 137Cs concentrations by measuring the radioactivity of suspended particulate matter (SPM) collected on filter tapes in SPM monitors which were operated even after the accident. This new dataset focused on the period of March 12–23, 2011 just after the accident, when massive radioactive materials were released from the FD1NPP to the atmosphere. Overall, 40 sites of the more than 400 sites in the air quality monitoring stations in eastern Japan were studied. For the first time, we show the spatio-temporal variation of atmospheric 137Cs concentrations in the FP and the Tokyo Metropolitan Area (TMA) located more than 170 km southwest of the FD1NPP. The comprehensive dataset revealed how the polluted air masses were transported to the FP and TMA, and can be used to re-evaluate internal exposure, time-series radionuclides release rates, and atmospheric transport models.

Long-term assessment of airborne radiocesium after the Fukushima nuclear accident: re-suspension from bare soil and forest ecosystems

“…Since then, a number of studies have been conducted, particularly during the months that followed the accident. These assessments include primary emission estimations (Chino et al, 2011;Danielache et al, 2012;Stohl et al, 2012;Terada et al, 2012;Katata et al, 2012aKatata et al, , b, 2015Winiarek et al, 2012Winiarek et al, , 2014Hirao et al, 2013;Saunier et al, 2013;Yumimoto et al, 2016;Danielache et al, 2016), field observations (ground aerosol sampling: Masson et al, 2011Masson et al, , 2013Kaneyasu et al, 2012;Adachi et al, 2013;Tsuruta et al, 2014;Igarashi et al, 2015;Oura et al, 2015;aircraft measurements: NRA, 2012; and measurements carried out on foot: Hososhima and Kaneyasu, 2015), and numerical simulations of transport and depositions (deterministic simulation: Chino et al, 2011;Morino et al, 2011;Yasunari et al, 2011;Stohl et al, 2012;Terada et al, 2012;Katata et al, 2012a, b;Winiarek et al, 2012Winiarek et al, , 2014Hirao et al, 2013;Saunier et al, 2013;Katata et al, 2015;Yumimoto et al, 2016;Danielache et al, 2016; deterministic simulation with sensitivity runs: Morino et al, 2013;Adachi et al, 2013;Groëll et al, 2014;Saito et al, 2015;…”

The Impact of Surface Wind Data Assimilation on the Predictability of Near-Surface Plume Advection in the Case of the Fukushima Nuclear Accident

“…Furthermore, wet deposition in the model was turned off to avoid a plume disappearance caused by the erroneous precipitation in the model. The modeled plume arrival times were validated by comparing them with the hourly averaged radioactive cesium concentrations measured by Tsuruta et al (2014) and Oura et al (2015). Tsuruta et al (2014) developed a method to retrieve the hourly averaged concentrations of radioactive cesium in the lower atmosphere using suspended particulate matter (SPM) sampling tapes with a detection limit of less than 0.6 Bq m −3 during the Fukushima nuclear accident.…”

“…The modeled plume arrival times were validated by comparing them with the hourly averaged radioactive cesium concentrations measured by Tsuruta et al (2014) and Oura et al (2015). Tsuruta et al (2014) developed a method to retrieve the hourly averaged concentrations of radioactive cesium in the lower atmosphere using suspended particulate matter (SPM) sampling tapes with a detection limit of less than 0.6 Bq m −3 during the Fukushima nuclear accident. The SPM tapes were collected from the air pollution monitoring network managed by the national government and maintained by prefectural governments.…”

“…The SPM tapes were collected from the air pollution monitoring network managed by the national government and maintained by prefectural governments. Tsuruta et al (2014) and Oura et al (2015) reported the concentration data at 99 SPM-tape sampling stations. However, we screened these stations to clearly detect the radioactive plume arrival, which is discussed in the next section.…”

“…The radioactive cesium plume was dispersed from a single source (the Fukushima Daiichi Nuclear Power Plant). The surface concentration of the plume was measured at many locations at a high frequency and with high accuracy (Tsuruta et al 2014;Oura et al 2015). This point source plume is advantageous due to its simple tracer isolation and validation without cross-dispersion.…”