Dispersion of radiocesium-contaminated bottom sediment caused by heavy rainfall in Joso City, Japan - Fig 3

<p><b>Correlation between count rates inside and outside the car (<i>p</i> = 0.781) (a). Correlation between dose rates in air and count rates outside the car (<i>p</i> = 0.215) (b).</b> The absorbed dose rates in air were calculated using software that implemented the 22 × 22 response matrix method [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171788#pone.0171788.ref009" target="_blank">9</a>]. The slopes of these regression lines were used as the shielding factor and the dose conversion factor, respectively.</p

The survey routes for measuring the absorbed dose rates in Joso City before (a) and after (b) the heavy rainfall disaster.

<p>Car-borne surveys were carried out using a 3-in × 3-in NaI(Tl) scintillation spectrometer in August and October 2015. Total distances traveled were 59.3 km and 88.0 km, respectively. The fixed-point observations outside the car were also done for 10 min at 11 locations. These route maps were drawn using the Generic Mapping Tools (GMT) created by Wessel and Smith [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171788#pone.0171788.ref003" target="_blank">3</a>].</p

Activity concentrations of ¹³⁴Cs and ¹³⁷Cs in soil samples after the heavy rainfall disaster.

<p>Activity concentrations of ¹³⁴Cs and ¹³⁷Cs in soil samples after the heavy rainfall disaster.</p

The distribution maps of absorbed dose rate in air in Joso City before (a) and after (b) the heavy rainfall disaster.

<p>The map for August 2015 (a) was drawn using 169 data and that for October 2015 (b) was drawn using 623 data.</p

Absorbed dose rate in air from natural and artificial radionuclides before and after the 2015 heavy rainfall disaster.

<p>Absorbed dose rate in air from natural and artificial radionuclides before and after the 2015 heavy rainfall disaster.</p

Transition of representative absorbed dose rate in air between October 2012 and April 2014 at Akebono-cho, Kashiwa City (Fig 1B).

<p>This figure was drawn using data published by the Kashiwa City Office [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171100#pone.0171100.ref029" target="_blank">29</a>]. These data were measured by the car-borne survey technique using a CsI(Tl) scintillation spectrometer.</p

The distribution map of absorbed dose rate in air for the Tokatsu area.

<p>A minimum curvature algorithm was used for the data interpolation using the Generic Mapping Tools of Wessel and Smith [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171100#pone.0171100.ref014" target="_blank">14</a>]. This map was drawn using 2,165 data.</p

Correlation between count rates inside and outside the car (A) and between absorbed dose rate in air and count rates outside the car (B).

<p>The slopes of these regression lines were used as the shielding factor (1.42) and the dose conversion factor (0.14). The standard errors of regressions were shown as error bars.</p

Survey routes for measuring the absorbed dose rates in air.

<p>A car-borne survey was carried out using a NaI(Tl) scintillation spectrometer in June 2015. Total distance traveled was 669 km. The fixed-point measurements outside the car were also carried out for 10 min at 43 locations.</p

The location of Chiba Prefecture relative to the Fukushima Daiichi Nuclear Power Plant (A) and the detailed location of the Tokatsu area in the northwestern part of Chiba Prefecture (B) which includes six cities: 1, Noda City; 2, Nagareyama City; 3, Kashiwa City; 4, Abiko City; 5, Matsudo City; and 6, Kamagaya City.

<p>The location of Chiba Prefecture relative to the Fukushima Daiichi Nuclear Power Plant (A) and the detailed location of the Tokatsu area in the northwestern part of Chiba Prefecture (B) which includes six cities: 1, Noda City; 2, Nagareyama City; 3, Kashiwa City; 4, Abiko City; 5, Matsudo City; and 6, Kamagaya City.</p