Paper No. 18
Presentation Time: 1:15 PM
HANDHELD X-RAY FLUORESCENCE (XRF) AS A RAPID AND RELIABLE TOOL FOR ENVIRONMENTAL MONITORING OF SOLIDS
X-ray fluorescence (XRF) works by finding the spectral signature of elements in solid phase samples. XRF technique is non-destructive and useful because it can be used to preliminarily detect elements that are potentially hazardous, at no additional cost. Some undesirable elements found in the environment are As, Cd, Pb and radioisotopes. Hand-held XRF devices return results more quickly than other methods used to detect elements in soil and other materials such as acid digestion. Within seconds, soil composition can be examined and quantified. Due to portability of XRF, one can obtain a large number of readings in situ. Initial results acquired via XRF can serve to determine if further, more accurate testing is merited. Increasing the XRF integration time of the sample will detect more elements and enhance the quantification of the data. In situ analysis of the solids will measure lower concentrations than laboratory samples enhanced by sieving, tight packing, and suitable thickness. In one of the experiments, Cr, Va, and Ba, the measurement will be lower by 20-30 % (Thermo Niton NDT XL2 Web XL2 Resource Guide). The standards that were used in this experiment were SiO2 (99.95%), CCRMP Till-4, Nist 2709a, Nist 2780 and RCRA (As, Ba, Cd, Cr, Pb, Se, & Ag). The standards were used to examine the consistency of elements when the time was increased under the XRF evaluation. During the SiO2 analysis for 90 seconds, the results were 2% Cd. However, with the 180 seconds scan, there was 7%. Most of the results were within 5% of std. Tests were done with different materials to check the consistency with the standards. Polyethylene sample cups were used (31 to 40 mm in diameter with collar) as well as red plastic caps and bottle caps. All samples were sealed with X-ray Mylar window film of 2.5um. In Jamaica Bay, New York, radioactive Thorium was detected in sediment samples by XRF. Even though the quantity is low, it represents that this element may be present and should be further investigated by more accurate methods. The preliminary results give direction for future investigation. By using XRF technology, we can acquire results rapidly and protect the environment from being adversely affected. Further testing of sediment samples collected from Baisley Pond, Meadow Lake, and Oakland Lake (Queens County, New York City) is continuing.