Concentrations of trace and major elements in Mission-Progresso (Texas) soils

Neutron Activation Analysis (NAA) was applied to determine trace and major elements in Mission-Progresso (Texas) soils. The Rio Grande river runs along the USA-Mexico border. The soil samples were collected at Mission and Progresso areas of the Rio Grande riverbank in the USA side. Soils were analyzed for the presence of toxic effluents due to human activities that might affect agricultural products and health because one of the possible paths of intoxication is the agricultural product consumption. Dried, sieved, and blended soil samples (∼1.5 g) were irradiated at the UT Austin TRIGA reactor at a thermal neutron flux of 1 x 1012 n cm-2s-1 and epithermal neutron flux of 1 x 1011 n cm-2s-1. Different irradiations, decay, and counting times were combined to determine concentration and detection limits of 21 elements which represent four areas in Mission-Progresso (Texas) with the aim to achieve a consistent characterization. NIST certified reference materials were used in relative analysis and also to determine the accuracy and reproducibility values. The neutron flux was monitored using sulfur flux monitor wires. Normal and Compton suppression gamma ray spectrometers were used to detect different gamma ray energy peaks and this Compton system greatly reduces the background. Concentrations are evaluated in per cent and parts per million and errors are within acceptable levels and these values are compared with values reported in literatures from other countries. The results do not show significant contaminations neither from the Rio Grande river nor from nearby industries. (author)