COLLECTION AND ANALYSIS OF RADON IN WATER

Transcription

1 CARST Radon Conference - Congrés Radon ACSTR Montreal, Quebec April 24-26, 2016 COLLECTION AND ANALYSIS OF RADON IN WATER Michael Kitto, PhD Research Scientist Laboratory of Inorganic and Nuclear Chemistry Wadsworth Center, New York State Department of Health, Albany michael.kitto@health.ny.gov Telephone: (518) Website:

2 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 g) Drinking the water The cells in your stomach could be exposed to increased radiation 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.

3 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.

4 Existing and planned max. limits for radon in water Recommended State MCL (Bq/L) Massachusetts 370 Connecticut 185 Vermont 185 Maine 148 Rhode Island 148 New Hampshire 74 New Jersey US EPA proposes radon in water MCL of 11 Bq/L 1999 US EPA allows up to 148 Bq/L (MMM approach)

5 General 1-to-10,000 rule of transfer coefficient, 150 Bq/L in water 15 Bq/m3 in air (outdoor level) 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

6 Typical use : 284 liters per person per day

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8 15-Oct 16-Oct 17-Oct 18-Oct 19-Oct- 20-Oct 21-Oct 22-Oct 23-Oct 24-Oct CRM 148 Bq/m3 9PM bath 9AM bath 3900 Bq/m3 Air radon concentraion (Bq/m3)

9 Indoor radon conc. (pci/l) Bq/m Surficial radon levels are NOT related to groundwater radon radon laundry 11, Bq/L pci/l well water 0 04/13 04/14 04/15 04/16 04/17 04/18 04/19 04/20 04/21

10 Fish culture station (hatchery) Water = 81 Bq/L

11 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 spigot is ~15 L/min

12 Minimum volume of water (V; liters) that must be flushed V = pi r 2 L where r = the radius of the piping (m), L = the length of the piping (m), and pi = 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

13 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 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)

14 US EPA recommended collection method Insert syringe into bottom of funnel Water slowly overflows funnel Pinch hose to remove ALL air pockets

15 Fill syringe from center of bowl of water

16 Open bottle underwater

17 Fill syringe from bottom of funnel

18 Slide bottle under faucet

19 Submerged faucet Kitto preferred method

20 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.

21 Liquid scintillation counter can measure a series of radon cocktails. 5 cpm / dpm

22 Transfer of radon into a Lucas cell

23 Transfer of radon into a Lucas cell

24 Computer controlled Lucas cell counters

25 Electrets

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27 Rad-7 radon in water Pylon radon water test Gamma counting

28 RADON IN WATER INTERCOMPARISON Past participants: Federal lab 1 State lab 4 County lab 1 Private company 12 Private individual co. 2 University 3 Location of participants: 15 states and 1 international CA CO CT FL IA LA MA MD NC NH NJ NY PA SC WI non-us Current study Bulgaria 1 Canada 1 Finland 1 Estonia 1 France 2 Germany 1 Italy 10 Moldova 1 Montenegro 1 Poland 1 Portugal 2 Serbia 1 Spain 1 Sweden 1 U.S. 13

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30 925 Radon-in-water concentration (Bq/L) Liquid scint. Electret Gamma-ray spec. CRM Known +/- 25% of known Known = 693 Bq/L Participant

31 Known = 139 Bq/L

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33 SOURCES OF ERROR Collection (radon loss) Do duplicates, and report highest concentration Transfer (radon loss) Accounted for during standardization Measurement Calculation (equation, volume, decay, etc)

34 Remediation of radon in water If Rn-222 concentration is < 5000 pci/l If Rn-222 concentration is > 5000 pci/l may use GAC use aeration include UV or chlorination? Whole house or not? Unlikely for GAC Separate treatment for shower? Point Of Use (POU) : (under the sink) GAC Reverse Osmosis for example: Pur or Brita type devices (GAC + mole sieve)

35 Methods for remediation of radon in water Storage Tanks Blending (good water with the bad) Reverse Osmosis Activated Charcoal Aeration Units Scaling

36 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.

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

38 MOVIE Transfer of water from collection bottle to LSC vial

39 Note Teflon septum Questions?