Environmental influences on the accumulation of lead, cadmium, mercury, antimony, arsenic, selenium, bromine and tin in unicellular algae cultivated in Thailand and in Germany

The authors discuss the role of atmospheric dust emissions, rainfall, water quality, and fertilizers in the contamination of agricultural products by heavy metals. In order to study such contamination, the unicellular alga Scenedesmus obliquus was cultured under natural climatic conditions at a rural site in Thailand and an industrialized, heavily-polluted site in West Germany. Algae were harvested at regular intervals, and heavy metals were determined by neutron activation, except for lead and cadmium which were determined by atomic absorption spectrometry. The results, which are presented graphically, show the difference between the agricultural and industrial areas. Contamination in the latter was principally due to Pb and to a lesser extent antimony, cadmium, and selenium, while in the agricultural area superphosphate fertilizers are shown to be involved in contamination by arsenic, bromine, cadmium, and selenium.