Isotope tracers for lead and strontium sources in the Tieguanyin tea garden soils and tea leaves.

The concentrations of Pb & Sr in Tieguanyin tea leaves and soils from 15 tea gardens of Anxi, China, were determined and the sources of Pb & Sr in soil and leaf samples were analysed using isotope tracing technology. The results showed pH in soils had significant correlations to both acid-extractable Pb & Sr in soils and new leaves. The Pb concentration in leaves was significantly lower than that in soils, especially the acid-extractable Pb in soils. The low Bio-concentration Factor (BCF) indicated the bioavailable Pb in soils could not easily be transferred to leaves. The contribution rates of parent material were 61%-100% and 45%-100% for total Pb isotope and acid-extractable Pb isotope in soils, respectively, indicating a low impact of human activity. A sizeable influence of parent material for leaves was also observed, suggesting that Pb may be present in the dust-fall. Although Sr concentrations in leaves were not high, they exceeded that in soils. The high BCF also indicated that tea has a high capacity to accumulate Sr, with the coincidence that Sr87/Sr86 in the acid-extractable isotope in soils were similar to new leaves. A Pb-Sr joint tracer indicated that Sr in old and new leaves may be influenced by parent material and anthropogenic sources, respectively.

Potential exposure to metals and health risks of metal intake from Tieguanyin tea production in Anxi, China.

The metal content of Tieguanyin tea from Anxi, Southeast China, was studied. Leaching experiments were designed based on the local tea-drinking habits, and tea infusions were prepared using three types of water and two methods of soaking tea. Twelve metals (Cd, As, Cr, Pb, Se, Sb, Ag, Tl, Cu, Zn, Be, and Ba) were measured by inductively coupled plasma mass spectrometry (ICP-MS), and a human health risk assessment was performed. The results showed that the quality of water used for steeping tea has a direct effect on the leaching concentrations of metals in the tea infusion and this effect can be reduced by using pure water or commercially available drinking water. Further, the two tea-soaking methods used by local residents can reduce the metal intake. The health risk assessment determined that the carcinogenic risk values of Cr, As, and Pb (Cr > Pb > As) were within an acceptable range (10-7-10-4); therefore, the concentrations of these metals in tea infusions do not pose substantial carcinogenic risk to tea drinkers. The results also indicate that the high concentrations of Tl in the tea infusions pose a substantial noncarcinogenic risk and may result from the dissolution characteristics of Tl and the water quality.