Global distribution of deltaD values in C-bonded hydrogen of soil organic matter

土壤中H（D）、C、N、S等元素的稳定同位素比值与土壤有机质（OM）的来源和周转有关，因为不完全（生物）化学反应会破坏稳定同位素。在全球范围内，降水中的D值与水汽在前往两极、穿越山脉或前往内陆的途中由于蒸发/冷凝相关的同位素分馏而经历的降雨事件的数量有关。由于植物生物合成依赖于反映降水中D值全球分布的当地水源，土壤有机质中C-键合H可能在全球范围内表现出地理有序的D值分布。然而，土壤有机质中的C-键合（D）值可能会局部修改有机质周转。我们的目标是：1）建立一种分析方法，（D值的C键H在土壤中，2）确定之间的关系，（全球范围内降水和土壤有机质C-键合H中的D值，3）量化分解对碳键的影响通过实验室培养和评估不同气候条件下土壤有机质C-键合H中D值的垂直分布，垃圾堆至底土）。拟议的项目增加了一个新的定量工具，在自然地理，以提高我们的理解，在全球范围内的碳封存和营业额。

Stable isotope ratios of various elements including H ((D), C, N, and S have been related to origin and turnover of soil organic matter (OM), because incomplete (bio)chemical reactions fractionate stable isotopes. On a global scale, the (D values in precipitation are related to the number of rain events that water vapor undergoes on its way to the poles, across mountains or towards inland because of evaporation/condensation-related isotope fractionation. As plants rely on local water sources that reflect the global distribution of (D values in precipitation for biosynthesis, C-bonded H in soil OM might show a geographically ordered distribution of (D values on a global scale. However, C-bonded (D values in soil OM might locally be modified by organic matter turnover. Our objectives are to 1) establish a method for the analysis of (D values of C-bonded H in soil, 2) determine the relationship between (D values in precipitation and in C-bonded H of soil OM on a global scale, 3) quantify the effect of decomposition on C-bonded (D values in soil OM with laboratory incubations and by assessing the vertical distribution of (D values in C-bonded H of soil OM in different climates (litter to subsoil). The proposed project adds a novel quantitative tool in Physical Geography to improve our understanding of C sequestration and turnover at the global scale.