早期成土过程中土壤有机磷的演化及关键机制——基于31-P和13-C核磁共振技术

Clarifying soil organic phosphorus (P) forms and transformations is a key to understand P biogeochemical cycles during the initial stage of pedogenesis. And it is difficult to quantify the effects of soil metal oxides and organic matters on the soil organic P. In this proposed project, both of solution 31-P NMR (Nuclear Magnetic Resonance) and solid 13-C NMR spectroscopy with a Hydrofluoric acid pretreatment, will be used to characterize changes of soil organic phosphorus forms and soil organic matters with soil age on a 120 year-old glacier chronosequence, Gongga Mt., Southwest of China. The forms and amounts of soil organic P, which are adsorbed by metal oxides and organic complex or incorporated within organic matters, will be evaluated quantitatively. And the coupled evolution of soil organic matters and organic P will be studied during the initial pedogenic processes. The results are useful to reveal the nutrients biogeochemical cycles and their relationship with plant succession on the ‘young’ glacier retreat areas, which emerge increasingly in alpine and high latitude areas because of global warming. It also benefits vegetation restoration and management in disturbed areas.

阐明土壤有机磷的形态及其转化机制是理解早期成土过程中磷生物地球化学循环的基础；而定量评估金属氧化物和有机质对有机磷的影响是阐明有机磷形态转化的难点。本研究拟针对贡嘎山冰川退缩迹地土壤时间序列（120年），在前期无机磷形态研究的基础上，采用液相31-P和固相13-C核磁共振技术（含氢氟酸预处理步骤）准确获取土壤有机磷和有机质的化学形态，定量评估被金属氧化物和有机质吸附或包含的有机磷的形态和数量，阐明土壤有机磷形态在早期成土过程中的演化特征，探讨有机磷与有机质形态随成土过程的耦合演化关系，揭示控制有机磷形态演化的关键机制。成果有助于理解因气候变暖引起的、越来越多的、年轻冰川退缩迹地上营养元素生物地球化学循环及其与植被演替之间的关系，可为扰动发生后植被的恢复和维护提供理论依据。

阐明土壤有机磷的形态及其转化机制是理解成土早期磷生物地球化学循环的基础。本研究选取贡嘎山冰川退缩迹地土壤时间序列（120年），采用化学浸提技术，定量研究了成土早期有机磷的积累过程和速率，冰川退缩120年后，土壤有机磷积累量达26.8 g m-2，平均积累速率为0.22 g m-2 yr-1，发现快速发育的植被为有机磷提供了充足的来源，而相对冷、湿的环境促进了有机磷的大量积累；采用核磁共振和湿化学分级技术，获取了不同成土阶段有机磷的化学形态，发现磷酸单酯随土壤年龄逐渐增加，而生物有效性较高的磷酸双酯的含量未呈现时间变化趋势；磷酸单酯占有机磷的38-58%，以肌醇磷酸盐为主，与金属化合物和有机质形成较稳定磷-金属-有机质复合体；磷酸双酯约占有机磷的2.0-3.3%，以DNA为主，主要来自土壤微生物。快速降低的土壤pH导致的酸性环境，以及快速风化作用而形成的铁和铝化合物的保护作用，是海螺沟冰川退缩区土壤中磷酸单酯，尤其是肌醇磷酸盐不断积累的关键机制。本研究的结果有助于阐明早期成土过程中磷的生物地球化学循环及其与环境和生物因素之间的关系。