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)

Typical use :

284 liters per person per day

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

Fish culture station (hatchery) Water = 81 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

Fill syringe from center of bowl of water

Open bottle underwater

Fill syringe from bottom of funnel

Slide bottle under faucet

Submerged faucet – Kitto preferred 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.

Liquid scintillation counter can measure a series of radon cocktails.

5 cpm / dpm

Transfer ofradon intoa Lucas cell

Transfer ofradon intoa Lucas cell

Computer controlled Lucas cell counters

Electrets

Rad-7 radon in water Pylon radon water test

Gamma counting

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

Known = 139 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.

Water softener can be source of high radon in water (and air?)

MOVIE

Transfer of water from collection bottle to LSC vial

Questions ?

Note Teflon septum