Date: Thu, 8 Apr 1999 16:14:16 -0600 To: chiefs.97, chiefs.91, chiefs.94 From: Dennis Helsel Subject: TE News v.5 Radium Cc: nst, test, traces, nlt, wqspecs, wlapham, lshelton, rhirsch, zszabo Radium in Ground Water Trace Element Synthesis News v.5 Previous TE news blurbs: v.1 Trace Element Synthesis Staffing and plans 2/10/99 v.2 Changes to TE lab methods for bed sediments 2/19/99 v.3 Well Selection for Subunit Surveys 2/26/99 v.4 Mercury in Streambed Sediments 3/04/99 Radium in Ground Water NAWQA subunit surveys randomly select wells from aquifers used for supply, and so generally represent the quality of the used resource within large portions of a Study Unit. Domestic wells are most commonly sampled, and provide about the only data available on homeowner wells nationwide. In addition, results compare to those for small public-supply systems tapping the same part of the aquifer. The 1997 study units are doing most of their subunit survey data collection in FY99. Trace elements currently analyzed by schedule 2703 include many metals. However, radon-222 is the only radiochemical currently analysed. USEPA is presently revising its radiochemical MCLs based on risks for incurring cancer, and finds few ambient data on which to base its decisions. Current regulation for rads is in three parts: limiting combined radium 226/228 to 5 PCi/L; a combined standard of 4 mrems for beta emitters; and a gross alpha standard for all alphas of 15 pCi/L, not including radon and uranium. (see: http://www.epa.gov/OGWDW/standard/pp/radnucpp.html ). The gross alpha and beta standards give little information on what species might be causing the violation, but radium, lead-210 and polonium-210 are the chief suspects. A decision on whether to revise the radium 226/8 limit will come by December 2000. The radium species are important contaminants of emerging concern. In a District coop study, Zoltan Szabo (NJ District) found that radium-226 and 228 exceeded MCLs in 33% of wells in a drinking water aquifer in the coastal plain of New Jersey (Fact Sheet -062-98). Concentrations were highest under ag areas, attributed to changing pH from agchemical applications. Low pH and anoxic waters define the conditions where radium is most likely to be high. Domestic wells had higher concentrations than did public supply wells. Then, considerable radium-224 concentrations were found in coastal plain wells when samples were quickly analyzed. Radium-224 has been an unrecognized problem affecting consumers, because standard holding times prior to sample analysis have been on the order of several weeks, while the half-life of radium-224 is only 3.6 days (long enough to be consumed). Concentrations of 224 alone were sufficient to cause exceedances of the alpha-particle standard in many cases. The state of NJ, DEP has done much more work as a result, and the State of Maryland has looked for and found similar results in its coastal plain. Then in FY98 USEPA funded a small USGS effort to collect information on radiochemicals in source waters across the United States. Raw water samples were collected by water utility personnel at 100 plants. Zoltan Szabo was again the project chief, and Ann Mullin (NWQL) set up the contract laboratory pipeline, which involved very quick turnarounds for 224 analysis. Samples were shipped to the contract lab AND analyzed within 48 hours of collection. Rates of detection for polonium-210 and lead-210 were infrequent. However, the radium species were frequently detected. Radium-224 exceeded a concentration of 7 ug/L (which is the current "concentration concern level" for Ra-224) in about 11% of wells. Radium-226 and 228 were also present at or above their standard in 17 to 25 percent of samples. The current data set of 100 wells in 27 states is not sufficient to correlate concentrations with geologic conditions, source type, or other ancillary variables. Little in the way of ancillary information was available for water drawn by these utilities. I have been working to obtain funding from USEPA to begin sampling nationwide for radium in subunit survey wells. Some funding appears to be available. NAWQA subunit surveys provide the only opportunity to date to measure radiochemicals in drinking water wells which have reliable ancillary information across the Nation. USGS could begin to provide information on the frequency of occurrence of radium species as a function of land use, geology/geochemistry, and water quality conditions. The answers to "where" and "why", not just straight percentages. The results will have a significant impact on the information base of what may be the highest cancer health risk in groundwater. It would provide information essential to determining which types of wells are most likely to have recurring exceedances for radioactivity under the upcoming revised EPA regulations. Stay tuned. -------------------------------------------------------------- Dennis R. Helsel Ph: (303) 236-2101 x227 Trace Element National Synthesis Fax: (303) 236-4912 U.S. Geological Survey PO Box 25046, MS-415 dhelsel@usgs.gov Denver, CO 80225