Water residence time and temperature drive the dynamics of dissolved organic matter in Alpine lakes in the Tibetan Plateau

This dataset contains data from an investigation into the drivers on the spatial distribution of dissolved organic matter in alpine lakes in the Tibetan Plateau described in the paper: "Du Y., Chen F., Xiao K., Song C., He H., Zhang Q., Zhou Y., Jang K.-S., Zhang Y., Xing P., Liu Z., Zhang Y. and Lu Y. 2021. Water Residence Time and Temperature Drive the Dynamics of Dissolved Organic Matter in Alpine Lakes in the Tibetan Plateau, Global Biogeochemical Cycles 35(11), e2020GB006908". The primary objectives of the study were to: (i) evaluate the spatial variability of the amount, source, and composition of DOM from alpine lakes on the Tibetan Plateau, and (ii) determine the primary environmental controls and mechanisms responsible for the spatial variability. At first, we collected 35 water samples from 25 lakes distributed in the northwestern (33.1–33.6 °N, 78.9–80.4°E), central (30.5–31.9°N, 88.3–89.4°E) and southeastern (28.6–29.1 °N, 90.4–90.8°E) regions of the plateau. We characterized water chemistry and DOM composition in these lakes by measuring dissolved organic carbon (DOC) and DOM optical properties (i.e., absorbance and fluorescence spectroscopy). DOM compositions of three lakes of different water residence times (WRTs) were further analyzed using ultrahigh-resolution molecular techniques (i.e., electrospray ionization-assisted Fourier transform-ion cyclotron resonance mass spectrometry, ESI FT-ICR MS). Secondly, we collected the indices of climatic characteristics (i.e., mean annual temperature, mean annual precipitation, and mean annual irradiation period) and lake hydrology (i.e., catchment area, lake area, mean depth and water residence time) of the sampling lakes. Thirdly, we performed statistical analysis to determine the primary environmental control and predictors of the spatial variability in lacustrine DOM on the Tibetan Plateau. The statistical analyses included non-parametric Kruskal-Wallis with Dunn post hoc test, spearman's bivariate correlations, redundancy analysis, and linear regression models. Main results of this work are that (1) DOM in Tibetan alpine lakes is mediated more by in-lake production and transformations than by catchment inputs; (2) water residence time (WRT) of lakes and mean annual temperature (MAT) accounted for 30–59% of the spatial variance of the abundance of chromophoric DOM (CDOM) and fluorescent DOM (FDOM); (3) Alpine lakes on the Tibetan Plateau would play a more active and prominent role in regional and global carbon cycles in the face of climate change.

本数据集来源于论文《Du Y.、Chen F.、Xiao K.、Song C.、He H.、Zhang Q.、Zhou Y.、Jang K.-S.、Zhang Y.、Xing P.、Liu Z.、Zhang Y. 与 Lu Y.，2021，水停留时间与温度驱动青藏高原高山湖泊溶解有机质动态，Global Biogeochemical Cycles，35(11)，e2020GB006908》中所描述的研究，该研究聚焦青藏高原高山湖泊溶解有机质（dissolved organic matter, DOM）空间分布的驱动因子。

本研究的核心目标有二：其一，评估青藏高原高山湖泊溶解有机质的含量、来源与组成的空间异质性；其二，明确驱动该空间异质性的主要环境调控因子与作用机制。

首先，本研究从青藏高原西北部（33.1°N~33.6°N，78.9°E~80.4°E）、中部（30.5°N~31.9°N，88.3°E~89.4°E）与东南部（28.6°N~29.1°N，90.4°E~90.8°E）的25个湖泊中采集了35份水样。通过测定溶解有机碳（dissolved organic carbon, DOC）以及DOM的光学特性（即吸光度与荧光光谱），对这些湖泊的水化学特征与DOM组成进行了表征。针对3个不同水停留时间（water residence time, WRT）的湖泊，进一步采用超高分辨分子技术——即电喷雾电离辅助傅里叶变换离子回旋共振质谱（electrospray ionization-assisted Fourier transform-ion cyclotron resonance mass spectrometry, ESI FT-ICR MS）——分析其DOM组成。

其次，本研究收集了采样湖泊的气候特征指标——包括年平均气温（mean annual temperature, MAT）、年平均降水量与年平均日照时长——以及湖泊水文指标——包括集水区面积、湖泊面积、平均水深与水停留时间。

其三，本研究开展了统计分析，以明确驱动青藏高原湖泊DOM空间异质性的主要环境调控因子与预测因子。本次统计分析涵盖非参数Kruskal-Wallis检验结合Dunn事后检验、斯皮尔曼双变量相关性分析、冗余分析以及线性回归模型。

本研究的主要结论如下：(1) 青藏高原高山湖泊的DOM主要由湖内生产与转化过程调控，而非流域输入；(2) 湖泊水停留时间（WRT）与年平均气温（MAT）可解释有色溶解有机质（chromophoric DOM, CDOM）和荧光溶解有机质（fluorescent DOM, FDOM）含量30%~59%的空间变异；(3) 在气候变化背景下，青藏高原高山湖泊将在区域与全球碳循环中发挥更为活跃且关键的作用。