茶叶与产地环境中稳定同位素和矿物元素特征及其相关性研究

为探究茶叶与茶园土壤、灌溉水源等产地环境中稳定同位素和矿物元素特征及其相关性,采用元素分析同位素质谱联用仪(EA-IRMS)和电感耦合等离子体质谱仪(ICP-MS)对山东日照和崂山的茶叶、栽培土壤及灌溉水源中4种稳定同位素比率(δ¹³C、δ¹⁵N、δD和δ¹⁸O)和23种矿物元素含量(Na、Mg、Al、K、Ca和Sr等)进行测定。结果显示,两地区中稳定同位素和矿物元素具有区域性特征,通过对茶叶中4种稳定同位素与栽培土壤(δ¹³C和δ¹⁵N)、灌溉水源(δD和δ¹⁸O)分别进行线性相关分析,结果表明,茶叶与栽培土壤中的δ¹⁵N相关性最大,R²为0.450 7,其次分别为栽培土壤中的δ¹³C(R²=0.289 5)、灌溉水源中的δ¹⁸O(R²=0.156 2)和δD(R²=0.021 4);同时,利用热图技术对茶叶与栽培土壤、灌溉水源中稳定同位素和矿物元素进行差异性及多重相关性分析,结果表明,茶叶与栽培土壤中δ¹³C呈较强负相关,而与灌溉水源中δ¹⁸O则无明显相关性。同时茶叶与栽培土壤中矿物元素也存在一定差异性,而茶叶中Cd、Li、Co、Sr、Mo与栽培土壤中相应矿物元素相关性较大。本研究初步揭示了稳定同位素在茶叶与栽培土壤、灌溉水源间的分馏情况以及与矿物元素的相关性,对研究农产品与环境因素间同位素分馏和元素累积规律具有一定的参考价值。

Feature of Stable Isotope and Mineral Element Composition From Tea and Its Environment With Correlation Analysis

To explore the correlation of stable isotopes and mineral element compositions of tea with its cultivated soil and water source, 4 stable isotope ratios (i.e. δ¹³C, δ¹⁵N, δ²H, δ¹⁸O) and 23 mineral elements contents (Na, Mg, Al, K, Ca, Sr, etc.) from tea, soil and water samples collected in pairs from Rizhao and Laoshan districts, Shandong province, were analyzed by isotope ratio mass spectrometers (IRMS) and inductively coupled plasma mass spectrometers (ICP-MS), respectively. The results showed that δ¹³C, δ¹⁵N, δ²H, δ¹⁸O values and mineral elements signatures of tea from Rizhao district and Laoshan district were significantly different. The correlations of stable isotope signatures of tea with that of soil (δ¹³C, δ¹⁵N) and water source (δD, δ¹⁸O) were comprehensively investigated by linear regression analysis, respectively. δ¹⁵N values of tea and cultivated soil were considerably correlated (R²=0.450 7), while δ¹³C values was not highly correlated (R²=0.289 5). Moreover, the correlations of both δ¹⁸O and δD values in tea with water source were very low, R² was just 0.156 2 and 0.021 4. Furthermore, the correlations of stable isotopes and mineral elements were presented using multi-variable heat map, which demonstrated the significant negative correlation of δ¹³C values between tea and soil, and no significant correlation of δ¹⁸O between tea and water source. Meanwhile, the correlations between mineral elements in tea and soil were also different, which indicates that mineral elements of tea including Cd, Li, Co, Sr and Mo were considerably correlated with that of soil. This study reveals the fractionation of stable isotopes and the correlation of stable isotopes with different elements between tea, soil and water sources, which can be reference for the future study on the isotope fractionation and element accumulation for agricultural products and environmental factors.