CARST Radon Conference - Congrés Radon ACSTRMontreal, QuebecApril 24-26, 2016
COLLECTION AND ANALYSIS OFRADON IN WATER
M ichael Kitto, PhD
Research ScientistLaboratory of Inorganic and Nuclear Chemistry
W adsworth Center, New York State Department of Health, Albany
Email: michael.kitto@ health.ny.govTelephone: (518) 486-1476Website: www.nyradon.org
Why is radon a problem in drinking water?
Radon is soluble in water and dissolves into water as it passes through soil.
Exposures:
Inhaling radon gas
Radon is released from water into air when water is agitated or heated.Inhalation of radon increases your risk of developing lung cancer.
200 Bq = 12,000 dpm = 95,250,000 radioactive atoms (3.5 x 10-14 g)
Drinking the water
The cells in your stomach could be exposed to increased radiation.
1500 Bq/L in water over lifetime = <10 additional colon cancers
Radon adds <20 stomach cancers/year to the 26,000 cases/yr that occur in U.S.
Is my drinking water at risk?
1) Your drinking water is from a private groundwater supply,
the water contains some measurable level of radon (4 - 40,000 Bq/L).
(may be seasonal variation)
2) Your source is a municipal supply or from surface water (river or lake),
the water likely contains LOW levels (<4 Bq/L) of radon.
Read the annual report provided by the supplier.
Radon levels in water decrease when
1) water is agitated as it goes through the distribution system
2) when stored for some time, in a tank or reservoir.
Existing and planned max. limits for radon in water
RecommendedState MCL (Bq/L)Massachusetts 370 Connecticut 185 Vermont 185Maine 148 Rhode Island 148 New Hampshire 74 New Jersey 30
1991 US EPA proposes radon in water MCL of 11 Bq/L1999 US EPA allows up to 148 Bq/L (MMM approach)
Factors affecting contribution from water to air
1. Solubility of radon in water
2. Type of water-use activity
3. Amount of water used in building
4. Volume of building
5. Ventilation rate of building
General 1-to-10,000 rule of thumb
@1/10000 transfer coefficient,
150 Bq/L in water 15 Bq/m3 in air (outdoor level)
15-O
ct
16-O
ct
17-O
ct
18-O
ct
19-O
ct-
20-O
ct
21-O
ct
22-O
ct
23-O
ct
24-O
ct
0
10
20
30
40
Air
rado
n co
ncen
traio
n (B
q/m
3)CRM148 Bq/m39PM bath9AM bath
3900 Bq/m3
370
740
1110
1480
04/13 04/14 04/15 04/16 04/17 04/18 04/19 04/20 04/21
0
10
20
30
40In
door
rado
n co
nc. (
pCi/L
)
radon laundry
11,300 pCi/L well water
Surficial radon levels are NOT related to groundwater radon
370
740
1110
1480B
q/m
3
420 Bq/L
Recommendations for sampling of radon in water
Collect sample as near to well head as possible (prior to treatment, storage, etc.)This may be accomplished by sampling from an outside tap
Purge sufficiently long to get fresh sample.
Consider the following :
• length of water line• depth of well• diameter of water line• water flow rate• presence and size of pressure tank
Typical home water flow from an outside spigotis ~15 L/min
Minimum volume of water (V; liters) that must be flushed
V = pi r2 L
where r = the radius of the piping (m),L = the length of the piping (m), andpi = 3.14
Example: For a “fresh” water sample
• 2.5 cm diameter piping • well pump at 76 meter depth• 14 meters of piping through home
For this case, dispose of at least 50 liters of water
Reservoir/ holding tank present ? Expel twice the volume of tank
SAMPLE COLLECTION - Syringe method
Prior to use, calibrate the syringe volume to a known volume.
Remove any faucet aerator.
Supplies needed : • Funnel• Clear tubing with standard faucet fitting or slip-on faucet adapter• 10-15 ml syringe (preferably not needle type)• Glass scintillation vials with 10 ml scintillation fluid
SAMPLE COLLECTION - Bottle method
If using collection bottle, supplies needed include :
• glass bottles only• Teflon or aluminum lined cap (retards radon release)• taller rather than wider bottles (less surface area)
Insert syringe into bottom of funnel
Pinch hose to removeALL air pockets
Water slowlyoverflowsfunnel
US EPA recommended collection method
Analytical methods for measurement of radon in water
Liquid scintillation (EPA recommended)
Electret
Rad-7 and Pylon flow through
Lucas cell (EPA recommended)
Isotopic gamma
NOTE : Radon level in water sample does NOT equate to Ra-226 level.
Rn-222 and Ra-226 not in equilibrium in water sample.
To obtain Ra-226 concentration, wait 40 days and measure radon.
Past participants:Federal lab 1State lab 4County lab 1Private company 12Private individual co. 2University 3
Location of participants:15 states and 1 international
CA NCCO NHCT NJFL NYIA PALA SCMA WIMD non-US
RADON IN WATER INTERCOMPARISON
Current study
Bulgaria 1Canada 1Finland 1Estonia 1France 2Germany 1Italy 10Moldova 1Montenegro 1Poland 1Portugal 2Serbia 1Spain 1Sweden 1U.S. 13
12
33
45
67
78
910
1112
1314
1516
1718
1920
21
Participant
185
370
555
740
925R
adon
-in-w
ater
con
cent
ratio
n (B
q/L)
Liquid scint.
Electret
Gamma-ray spec.
CRM
Known
+/- 25% of known
Known = 693 Bq/L
SOURCES OF ERROR
Collection (radon loss) Do duplicates, andreport highest concentration
Transfer (radon loss) Accounted for during standardization
Measurement
Calculation (equation, volume, decay, etc)
Remediation of radon in water
If Rn-222 concentration is < 5000 pCi/L may use GAC
If Rn-222 concentration is > 5000 pCi/L use aerationinclude UV or chlorination ?
Whole house or not ? Unlikely for GACSeparate treatment for shower?
Point Of Use (POU) : GAC(under the sink) Reverse Osmosis
for example: Pur or Brita type devices (GAC + mole sieve)
Methods for remediation of radon in water• Storage Tanks
• Blending (good water with the bad)
• Reverse Osmosis
• Activated Charcoal
• Aeration Units
Scaling
REMEDIATION OF RADON IN WATER
Methods are capable of over 95 per cent reduction.
Aeration
• Utilizes natural tendency of radon to diffuse out of water into the air.• Air-stripping increases surface area of air-to-water contact• Radon released in off-gas• Many smaller bubbles in water releases more radon
Adequate ventilation is required to remove the radon.
Granular Activated Carbon Absorption
Water passes through granular activated carbon which absorbs the radon.
This system has the disadvantage that radioactivity can build up in the unit, which may require specialist disposal.