Distribution characteristics of trace mineral elements in tea garden soils of Guizhou region and their biological accumulation and response to tea quality

Background Camellia sinensis , a vital cash crop in southwest China, makes Guizhou Province renowned for its premium zinc-selenium (Zn-Se)-enriched tea. While soil trace elements influence tea plant growth and quality, previous studies have predominantly focused on geochemical features, leaving gaps in understanding their distribution in tea plantations, transfer to tea plants, and specific impacts on tea quality. This study investigates trace element distribution in the rock-soil-tea system across Guizhou’s major tea-growing regions, assesses their effects on tea quality, and identifies key factors regulating soil element levels, aiming to underpin the expansion of high-quality Zn-Se tea production and sustainable regional economic development. Methods Drawing on a prior survey of 146 surface soil (0 ∼ 20 cm) samples from Guizhou tea gardens, 36 representative tea gardens spanning 12 local tea-producing areas were chosen for field research. Soil profile samples (0 ∼ 20 cm, 20 ∼ 40 cm, 40 ∼ 60 cm) and tea leaves were collected to analyze the spatial variability of major minerals (aluminum (Al), iron (Fe), calcium (Ca), magnesium (Mg), phosphorus (P), potassium (K), sulfur (S)) and trace elements (manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), germanium (Ge), selenium (Se), strontium (Sr)), as well as trace element bio-accumulation and their correlations with tea quality. Soil and rock samples were digested with aqua regia, tea samples with concentrated HNO 3 , and elemental concentrations were quantified using inductively coupled plasma mass spectrometry (ICP-MS). Results Results revealed significant spatial heterogeneity in soil trace elements (Mn, Cu, Zn, Mo, Ge, Se, Sr), with Cu and Se showing the highest variability, followed by Zn and Sr, then Mn and Mo, while Ge exhibited the least variation. In surface soils, Se concentrations ranged from 0.23 to 1.50 mg kg −1 and Zn from 33.0 to 105.6 mg kg −1 ; 69.4% of surface soils met Se-enriched standards, but only 33.3% reached Zn-Se-enriched levels. Strong positive correlations were detected between soil and parent rock contents of Mn, Cu, Zn, Mo, Se, and Sr, particularly for Se and Cu. Geological age and parent rock type were identified as dominant factors shaping soil Zn and Se levels, with synergistic interactions among elements further promoting their enrichment in soils. Trace element levels in tea leaves varied markedly across regions ( P < 0.01), with Se showing the highest variability, followed by Zn and Sr. Biological accumulation coefficients ranked as Mn > Zn > Cu > Se > Sr > Ge > Mo. Zn and Se contents in leaves were strongly correlated with corresponding soil concentrations ( P < 0.01), especially for Se. Leaf Se ranged from 0.05 to 0.54 mg kg −1 , and Zn from 24.4 to 97.2 mg kg −1 . Among samples, 25.0% met the threshold for Se-enriched tea and 22.2% for Zn–Se co-enriched tea, with the latter showing clear geographic clustering consistent with soil Zn and Se distribution.