11. Conclusion and RecommendationsOur analyte data showed levels well within expected concentrations, and below EPA MCLs, i.e., action levels. Some uranium and the low but positive reading for some of the trace metals is also expected, due to all the mineral deposits in the region.
Our data corroborates the results of Nye County, illustrating a wide variation in groundwater chemistry and radiation activity. We think this is significant in understanding the environmental baseline, which could also vary substantially within the region. To fully understand factors influencing residents in the region downgradient of the NTS and potential Yucca Mountain Repository, HþME believes that existing water sampling should be expanded to encompass the spectrum of water chemistry that influences public health.
Another possible consequence of the wide variation in gross alpha and beta readings is that the profile of radioactive elements in the groundwater could vary, without triggering action for a more detailed analysis. HþME envisions the possibility of contamination from either the NTS or Yucca Mountain repository moving off-site and into the water supply, without activating the warning system. Residents could then be ingesting contaminants at low levels, but nonetheless possibly concentrating them in their bodies over time, well before it is known that these contaminants are in the water.
HþME also sees a need to determine the source of the radioactive variation within our analysis, and to a greater extent, within Nye County’s data. Is the variation due to localized pockets of mineral deposits, or does the geochemistry influence the existing radioactivity that is dissolved in the water? In other words, is there a non-uniform binding mechanism in play with the naturally occurring radioisotopes, like uranium, radium, thorium, etc? If these mechanisms exist, then they could affect the appearance and movement of contaminants coming from the NTS or Yucca Mountain Repository.
The significance of the small U-238/U-234 ratios, relative to natural isotopic abundances seen in the area, is not clear to us at this time. It does not seem to be of much concern to Nye County, as we have not received a response to our queries. Again, this may point to our perception that the Early Warning Drilling Program is not focused on an environmental baseline.
While the Nye County and Nevada Test Site early warning systems may effectively intercept elevated radionuclide contamination, neither seems to track the breakdown of various radioactive isotopes in sufficient detail to reconstruct the overall radiation count in the groundwater, or, therefore, the intake profiles of the residents in the area. HþME understands that it is crucial to establish an environmental baseline and connect health patterns to environmental factors. One such process is radiation dose reconstruction, which is near to impossible without this detailed baseline.
HþME, through this study, hopes to encourage water monitoring agencies to conduct a thorough and complete program of water monitoring and ongoing analysis well into the future. Research must also continue to address the uncertainties in the understanding of groundwater movement and contamination, and the possible “gaps” in the existing monitoring network. This must include key analytes to protect health and habitat, both now and in the future.
|