ASSESSING HEAVY METAL CONTAMINATION IN TEA AND TOPSOIL DUE TO APPLICATION OF HERBICIDES: DAMBETENNA TEA ESTATES, SRI LANKA

Abstract

Excessive accumulation of heavy metals in tea plantations may not only result in environmental contamination but also affect the quality and safety of tea production in Sri Lanka. Thus, the prime aim of this study is to assess the levels of Potassium (K), Magnesium (Mg), Copper (Cu), Zinc (Zn), Iron (Fe), Manganese (Mn), Lead (Pb), and Cadmium (Cd) in fresh tea leaves (green), processed (black) tea samples and soil of herbicides applied and non-applied tea plantation plots in Dambetenna tea estates, Sri Lanka. Soil and tea leave samples were collected using simple random sampling technique representing both the herbicide applied (treated) and the non-applied (controlled) tea plantation plots within six months period of time (n=36). The Microwave digestion system and Atomic Absorption Spectrometer (AAS) were used to analyse the levels of metal concentrations and the data were statistically analysed using the student’s t-test (95% confidence interval) in order to compare two plots in terms of heavy metal concentrations. Results revealed that in herbicides applied plots, the concentrations of heavy metals viz. Zn, Fe, and Pb are significantly higher (p<0.05) in soil and the levels of Pb are slightly higher (p<0.05) in green tea leaves and black tea samples. Overall, the present study gives insights into the heavy metal contamination levels in tea estate soil, green tea leaves, and black/processed tea samples under chemical weeding systems in Sri Lanka.