Vulnerability of a public supply well in a karstic aquifer to contamination.

To assess the vulnerability of ground water to contamination in the karstic Upper Floridan aquifer (UFA), age-dating tracers and selected anthropogenic and naturally occurring compounds were analyzed in multiple water samples from a public supply well (PSW) near Tampa, Florida. Samples also were collected from 28 monitoring wells in the UFA and the overlying surficial aquifer system (SAS) and intermediate confining unit located within the contributing recharge area to the PSW. Age tracer and geochemical data from the earlier stage of the study (2003 through 2005) were combined with new data (2006) on concentrations of sulfur hexafluoride (SF(6)), tritium ((3)H), and helium-3, which were consistent with binary mixtures of water for the PSW dominated by young water (less than 7 years). Water samples from the SAS also indicated mostly young water (less than 7 years); however, most water samples from monitoring wells in the UFA had lower SF(6) and (3)H concentrations than the PSW and SAS, indicating mixtures containing high proportions of older water (more than 60 years). Vulnerability of the PSW to contamination was indicated by predominantly young water and elevated nitrate-N and volatile organic compound concentrations that were similar to those in the SAS. Elevated arsenic (As) concentrations (3 to 19 microg/L) and higher As(V)/As(III) ratios in the PSW than in water from UFA monitoring wells indicate that oxic water from the SAS likely mobilizes As from pyrite in the UFA matrix. Young water found in the PSW also was present in UFA monitoring wells that tap a highly transmissive zone (43- to 53-m depth) in the UFA.

Methods for screening for hearing loss in older adults.

Two common screening tools for detecting hearing loss, the Hearing Handicap Inventory for the Elderly-Screening Version (HHIE-S) and Audioscope, are compared. One hundred eighty-five consecutive patients over age 60 at a primary care clinic received both screening tests followed by pure tone audiometry. Three criteria for hearing loss was considered: Speech Frequency Pure Tone Average > or = 25 dB; High Frequency Pure Tone Average > or = 25 dB; and Ventry and Weinstein's criteria of a 40 dB loss at 1.0 or 2.0 kHz. Ranges of respective operating characteristics for the Audioscope versus the HHIE-S were: sensitivities 0.64 to 0.96 versus 0.29 to 0.63; specificities 0.80 to 0.91 versus 0.75 to 0.93; and positive likelihood ratios 4.86 to 7.52 versus 2.42 to 4.27. Most patients preferred screening with the Audioscope (60%) over the HHIE-S (13%). The Audioscope is preferred by patients, and outperforms the HHIE-S using a variety of reference standard definitions.