Bioavailability of Soil‐Extractable Metals to Tea Plant by BCR Sequential Extraction Procedure

Abstract

This study principally describes the distribution of the heavy metals such as Cu, Pb, Cd, Co, Cr, Fe, Mn, Ni, and Zn in different soil fractions and different parts of tea plant, and plant availability with single correlation. For this purpose, soil and corresponding plant samples were collected from the three tea gardens in Rize, Turkey. Tea plant (Camellia sinensis), which were segmented into leaf, stem, and root, and also treated black tea samples, were dissolved with both wet and dry ashing procedures. The BCR sequential extraction method was used for extracting the metals bound to target phases in soil samples. The method was performed to extract the metals present in exchangeable and acid soluble (i.e., bound to carbonates), reducible (bound to Fe/Mn oxides), and oxidisable forms (bound to organic matter and sulphides) in the soil samples. The determination of heavy metals in tea and soil samples was performed by FAAS. The results obtained from the sample analysis were compared with their typical soil and plant contents. For determining accuracy of the methods used, recovery studies were done and the results were found to be satisfactory (between 76% and 102%). In order to understand the uptake of metal from soil to tea plant, correlation analysis was performed between the different physicochemical forms of soil metals and their concentrations in tea plant tissues. Correlation analysis results indicated that pseudototal content of the heavy metals in soils and their sum extracted with the sequential extraction procedure were poor indicators for heavy metal uptake by plants. For Cd and Mn elements, significant positive correlations (r = 0.923–0.996) were found between the metal contents in fraction 1 of the sequential extraction procedure for soils and their concentrations in roots, stems, and leaves of the tea plant.