Abstract

Background: Camellia sinensis is an important cash crop in southwest China. Guizhou Province is especially known for its high-quality zinc–selenium (Zn–Se)-enriched tea. Trace elements in the soil influence tea plant growth and tea quality. However, past studies have mainly focused on geochemical features, not on how these elements are distributed in tea plantations or how they affect tea quality. The way trace minerals move from soil to tea plants remains unclear. This study examines how trace elements are distributed in the rock–soil–tea system across Guizhou’s major tea-growing areas, assesses their impact on tea quality, and identifies key factors influencing soil element levels. These results support the expansion of high-quality Zn–Se tea production and promote sustainable regional economic development.
Methods: Thirty-six representative tea gardens from 12 tea-producing areas in Guizhou Province were selected for field investigation. Soil profiles samples (0-20 cm, 20-40 cm, 40-60 cm) and tea leaves were collected and analyzed to study the spatial variability of major minerals (Al, Fe, Ca, Mg, P, K, S) and trace elements (Mn, Cu, Zn, Mo, Ge, Se, Sr). The bio-accumulation of trace elements and their relationship with tea quality were also assessed. Soil and rock samples were digested with aqua regia, and tea samples with concentrated HNO₃. Elemental concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS) .
Results: The contents of trace elements (Mn, Cu, Zn, Mo, Ge, Se, Sr) exhibited significant spatial heterogeneity. Cu and Se showed the highest variability, followed by Zn and Sr, then Mn and Mo, while Ge was the least variable. In surface soils (0-20 cm), Se and Zn concentrations ranged from 0.23 to 0.50 mg·Kg -1 and 33.0 to 105.6 mg·Kg -1 , respectively. About 50% of the tea gardens met the standard for Zn-Se-enriched soil. Significant positive correlations were observed between the contents of Mn, Cu, Zn, Mo, Se, and Sr in soils and those in parent rocks, particularly for Se and Cu. Geological age and parent rock type were identified as dominant factors influencing Zn and Se levels. Synergistic effects among elements further promoted the enrichment of Zn and Se in soils.
Trace element concentrations in tea leaves varied significantly (P < 0.01) across the 12 regions, with Se exhibiting the greatest variation, followed by Zn and Sr. The order of biological accumulation coefficients was: Mn > Zn > Cu > Se > Sr > Ge > Mo. Significant correlations were found between Zn and Se in tea leaves and their corresponding soil concentrations (P< 0.01), especially for Se. The Se and Zn contents in tea leaves ranged from 0.05 to 0.54 mg·Kg -1 and 4.4 to 97.2 mg·Kg -1 , respectively. The distribution of Zn-Se-enriched tea gardens showed strong regional characteristics, closely linked to soil Zn and Se levels.