Zheng Xiaodi, Han Guilin, Liang Bin, Zhu Guangyou
Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China.
Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China.
Sci Total Environ. 2023 Apr 20;870:161945. doi: 10.1016/j.scitotenv.2023.161945. Epub 2023 Feb 3.
Understanding Zn biogeochemical cycling is necessary for monitoring Zn supply for plants and life during land use conversion, which is critical for environmentally sustainable development. But little is known about how the conversion of paddy soil to abandoned land affects the Zn isotope signature. A comparative field observation was conducted in northeast Thailand to investigate the Zn isotope footprint of paddy soils and abandoned paddy soils (PL and NPL). Our results show that Zn (τ : 0.04) slightly retains on PL, but is lost from NPL (τ from - 0.81 to - 0.24) to the river during weathering. Compared to PL (ΔZn: -0.29 ‰), more Zn isotopes might enter the river when rice cultivation ceases in NPL (ΔZn from -0.26 ‰ to -0.47 ‰). Rice harvest and then root decay might result in heavy Zn isotopes accumulating at the topmost soil in PL (δZn: 0.14 ‰) and short-term abandonment (1-2 years) in paddy soils (NPL1 δZn: 0.18 ‰). The release of assimilated Zn, and then the high adsorption of Zn in the Fe-SOM-metal(loid)s ternary system positively contribute to the high [Zn] in PL, while this was not observed in NPL. Our findings provide a comprehensive insight into the Zn isotope signature in response to the conversion of land-use types, which is beneficial for understanding the terrestrial Zn geochemical cycle.
了解锌的生物地球化学循环对于监测土地利用转换过程中植物和生命的锌供应至关重要，这对环境可持续发展至关重要。但对于稻田土壤向荒地的转化如何影响锌同位素特征却知之甚少。在泰国东北部进行了一项对比实地观察，以研究稻田土壤和废弃稻田土壤（PL和NPL）的锌同位素足迹。我们的结果表明，锌（τ：0.04）在PL上略有保留，但在风化过程中从NPL（τ从-0.81至-0.24）流失到河流中。与PL（ΔZn：-0.29‰）相比，当NPL停止水稻种植时（ΔZn从-0.26‰至-0.47‰），更多的锌同位素可能进入河流。水稻收获然后根系腐烂可能导致重锌同位素在PL的最上层土壤中积累（δZn：0.14‰）以及稻田土壤短期弃耕（1 - 2年）（NPL1 δZn：0.18‰）。同化锌的释放，然后锌在铁 - 土壤有机质 - 金属（类金属）三元体系中的高吸附对PL中高含量的[Zn]有积极贡献，而在NPL中未观察到这种情况。我们的研究结果全面深入地了解了土地利用类型转换对锌同位素特征的影响，这有助于理解陆地锌地球化学循环。
