Mh. Wong et al., TRACE-METAL CONTENTS (AL, CU AND ZN) OF TEA - TEA AND SOIL FROM 2 TEAPLANTATIONS, AND TEA PRODUCTS FROM DIFFERENT PROVINCES OF CHINA, Environmental geochemistry and health, 20(2), 1998, pp. 87-94
The present project aims to investigate the possible contamination of
teas with the trace metals: Al, Cu and Zn. Tea bushes sampled from two
tea plantations in the northern part of Guangdong Province accumulate
d higher concentrations of Cu and Zn in young leaves, and of Al in old
leaves. The analysis of the three metals in tea produced in different
provinces indicated higher Al levels in those obtained from Guangdong
and Yunnan Provinces, which may be due to the lower soil pH in these
areas. Green tea had the lowest Al concentration among the four types
of tea studied, as only the bud and two young leaves are used, whereas
older leaves are used for other types of tea (black, Oolong and Puerh
tea). The transfer of Al, Cu and Zn from soil to different parts of t
ea bushes was low in general, except for Zn at Lechang tea plantation
which next to a Pb/ Zn mine, where a higher transfer was observed from
young leaves to tea products, indicating possible metal contamination
during tea processing. However, low concentrations of Cu and Zn (less
than 0.07 mg Cu L-1 and 0.17 mg Zn L-1), and moderate amounts of Al (
2.1-2.5 mg L-1) were obtained in the tea liquor (1% hot water extracts
).