A combination of neutron and photon activation techniques have been developed and applied for detecting traces of heavy metals from water pollution sources. Air-dried portions of sediments from several regions of the lower Great Lakes, organic cultivated soils, and selected edible vegetation from a heavily-irrigated and fertilized marsh crop-growing area were subjected either to neutron irradiation for 25 to 50 h or to 15 to 44 MeV bremsstrahlung from the University of Toronto electron linear accelerator for 1 to 4 h. Many of the neutron activation determinations at low concentrations required post-activation chemical separations, whereas an advantage of the photonuclear technique for use with such environmental samples was that multielement determinations could be done completely by an instrumental method.

Elements of environmental interest determined in the activated samples included: arsenic, antimony, cadmium, chromium, lead, mercury, molybdenum, selenium, thallium, zinc, and several others. The concentration ranges involved were from 0.1 to 500 ppm, and the typical analytical accuracy achieved varied from 5 to 15 percent as verified by comparison with other techniques and with standard reference materials. These studies have helped to identify some heavy metal water pollution sources and to elucidate the fate of such metals in sediment, soil-water-vegetation ecosystems.