In the table below the plots, we are providing two numbers for each
of the isotopes. The first is a standard concentration unit of
Becquerel per liter (Bq/L) which describes the number of particles
decaying over the period of one second. For the general public, we have
converted this number to an exposure dose per liter consumed. The
number in parentheses is the number of liters of water that one would
need to consume to equal the radiation exposure of a single round trip
flight from San Francisco to Washington D.C. (0.05 mSv). For more
information on how this equivalent dose is calculated, the details are
here: How Effective Dose is Calculated
For example, in the rain water we collected in 18 hours between March
17 and March 18 we observe an activity of the isotope of I-131
(Iodine-131) of 4.26 Bq/l. At this level, you would need to drink 632
liters of this rain water to obtain the same radiation effects you
obtain on a round-trip flight between San Francisco and Washington D.C.
Therefore, the increase in radiation levels in the rain water due to the
events in Japan remain extremely small.
We will continue to monitor radiation levels in air and water in the
foreseeable future and will provide the measured radiation levels here.
As of 3/23/11 14:00, these numbers have been revised to account for
the half-lives of the various isotopes measured. This leads to a slight
increase in the previously reported numbers. Details can be found at
this link: Description of Activity Correction for Isotope Half-life.
Now the Minimum Detectable Activity (MDA) is plotted as a blue line
on these plots. The MDA represents the lowest level of measurement
where we can confidently report results. To find out more about how the
MDA is calculated, please visit How we calculate MDA.
|
|
Water Vol. (L) |
I131 |
I132 |
Cs134 |
Cs137 |
Te132 |
Be7* |
Data |
| Start |
End |
Liters |
Bq/L (liters**) |
Bq/L (liters**) |
Bq/L (liters**) |
Bq/L (liters**) |
Bq/L (liters**) |
Bq/L (liters**) |
|
| 3/17 18:00 |
3/18 12:00 |
4.425 |
4.65
(581) |
0.62 (432803) |
0.21 (11555) |
0.26 (10467) |
0.62 (39106) |
1.12 (1.45E6) |
data |
| 3/18 13:00 |
3/18 20:30 |
5 |
5.87
(460) |
0.46 (581296) |
0.12 (20318) |
0.13 (20379) |
0.38 (63386) |
1.42 (1.14E6) |
data |
| 3/18 20:40 |
3/19 10:00 |
5 |
4.02
(672) |
0.37 (739254) |
0.09 (27109) |
0.14 (19864) |
0.25 (95854) |
1.65 (9.85E5) |
data |
| 3/19 10:15 |
3/19 21:45 |
5 |
6.12
(441) |
0.26 (1.04E6) |
0.24 (10194) |
0.26 (10322) |
0.34 (71545) |
0.91 (1.78E6) |
data |
| 3/19 21:45 |
3/20 11:30 |
5 |
7.98
(339) |
0.59 (455150) |
0.27 (8880) |
0.20 (13413) |
0.54 (44696) |
0.83 (1.95E6) |
data |
| 3/20 11:30 |
3/20 18:45 |
2.826 |
4.49
(602) |
0.29 (933729) |
0.20 (12332) |
0.20 (13598) |
0.27 (91482) |
2.77 (5.84E5) |
data |
| 3/21 19:00 |
3/22 07:45 |
1.916 |
8.35
(324) |
0.17 (1.58E6) |
0.12 (19528) |
0.10 (25767) |
0.28 (85352) |
2.69 (6.0E5) |
data |
| 3/22 17:00 |
3/23 09:06 |
4 |
4.65
(580) |
0.15 (1.85E6) |
0.06 (37410) |
0.088 (30567) |
0.15 (164879) |
1.91 (8.47E5) |
data |
| 3/23 09:06 |
3/23 18:00 |
3 |
20.1
(134) |
0.94 (287410) |
0.39 (6166) |
0.49 (5554) |
0.49 (49728) |
3.11 (5.2E5) |
data |
| 3/23 18:00 |
3/24 11:02 |
3.5 |
7.63
(354) |
0.51 (525614) |
0.56 (4330) |
0.59 (4571) |
0.47 (51498) |
0.82 (1.95E6) |
data |
| 3/24 11:02 |
3/24 18:10 |
5 |
3.23
(836) |
0.17 (1.6E6) |
0.31 (7753) |
0.22 (12105) |
0.19 (125865) |
1.44 (1.1E6) |
data |
| 3/24 18:10 |
3/25 11:23 |
5 |
3.12
(863) |
0.32 (847764) |
0.51 (4736) |
0.52 (5159) |
0.27 (91391) |
1.42 (1.1E6) |
data |
| 3/25 11:23 |
3/26 10:15 |
5 |
1.52
(1782) |
0.10 (2.58E6) |
0.14 (17283) |
0.16 (17163) |
0.27 (91391) |
0.07 (2.26E7) |
data |
| 3/26 10:15 |
3/27 8:51 |
2 |
3.71
(728) |
0.15 (1.85E6) |
0.24 (10066) |
0.26 (10218) |
0.38 (64707) |
1.71 (947984) |
data |
| 3/27 8:51 |
3/28 14:10 |
2 |
1.56
(1734) |
0.10 (2.60E6) |
0.36 (6800) |
0.46 (4847) |
0.08 (300651) |
1.73 (935179) |
data |
* Be-7 is observed normally due to it being cosmogenically produced in the atmosphere
** The number in parentheses is the number of liters
of water that one would need to consume to equal the radiation exposure
of a single round trip flight from San Francisco to Washington D.C.
(0.05 mSv). To see how we calculate these numbers, please visit our explanation of the equivalent dose calculation.
The raw data in the last column can be compared to the background spectrum of deionized water.
The following are results for rain water samples taken on the roof of
Etcheverry Hall on UC Berkeley campus beginning on 3/17/2011.
