COMPARING DIFFERENT METHODS FOR QUANTIFYING LEAD IN SOILS AND VEGETABLES

Environmental issues associated with mining activities are found all over the globe and are well documented throughout literature. One of these problems is heavy metal contamination of soils, water and plants. This study focuses on lead contamination in soils and plants. Lead contamination is a serious environmental problem affecting many people living in mining towns or former lead mining areas. In places such as Kabwe, Zambia, Pb levels of over 25, 000 mg/kg have been reported in the environment, especially in sediments near old lead and cadmium mines. Dangerously high levels of lead have also been reported in blood samples of residents, especially children who play directly in the soils. This paper is part of a broader study investigating the extent of lead contamination in Kabwe, and the effectiveness of various plants and vegetables to remove lead from contaminated soils. The paper presents laboratory measurements of Pb uptake by plants and the various methods used to quantify concentrations in soils and plants. It compares colorimeters, spectrophotometers, spectrometer, ion-selective probe technology, XRF and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The significance of comparing different methods is to help determine the most cost effective and efficient method for quantifying lead in environmental samples. Preliminary results showed extremely high levels in plants and soils from a field site, near local homes. Very preliminary results also showed similar results from the colorimeter and ICP-MS. The study also showed that despite being the most cost effective, the ion-selective probes required the most time to calibrate and prepare for use.