Pedogenic carbonates: Forms and formation processes
Pedogenic carbonates: Forms and formation processes
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DOI：
10.1016/j.earscirev.2016.03.003
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发表时间：
2016-06
影响因子：
12.1
通讯作者：
Kazem Zamanian;K. Pustovoytov;Y. Kuzyakov
中科院分区：
文献类型：
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作者：
Kazem Zamanian;K. Pustovoytov;Y. Kuzyakov
土壤是最大的陆生碳(C)库，包含有机碳和无机碳。土壤无机碳（SIC）经常被忽视，因为(1)它部分来自土壤母质遗产，(2)它经历缓慢的形成过程，(3)与大气CO2的交换非常缓慢。然而，碳化硅的全球重要性反映在碳化硅将长期的地质碳循环与快速的生物碳循环联系起来，并且这种联系正在土壤中进行。此外，碳化硅的重要性至少与土壤有机碳（SOC）一样高，特别是在半干旱和干旱气候中，碳化硅构成了最大的碳库。根据碳酸盐的来源、形成过程和形态，将土壤中的碳酸盐分为三大类：地成因碳酸盐（GC）、生物成因碳酸盐（BC）和成土碳酸盐（PC）。本文综述了目前有关PC形态和形成过程的资料和理论，并将其与环境因素联系起来。在描述了PC的一般形成原理之后，我们提出了PC特征的具体形式和形成过程，以及利用它们来重建土壤形成因素和过程的可能性。详细描述了以下PC：蚯蚓生物球石、根石和钙化根、下包覆层、结节、碎屑包覆层、钙化层和层状帽。第二部分综述了PC的同位素组成：δ13C， Δ14C和δ18O，以及13c和18o的块状同位素Δ47。PC同位素特征有助于重建其形成环境：主要植被（δ13C）、温度（δ18O和Δ47）和PC形成年龄（Δ14C）。讨论了地层后PC再结晶在重建和定年研究中的不确定性，并总结了考虑再结晶的简单方法。在此基础上，提出了施肥和土壤管理对土壤磷肥影响的研究方向。综上所述，PC是SIC的重要组成部分，反映了土壤的时间、阶段和形成过程。对PC形成机制的理解是预测陆地碳储量和全球碳循环变化，并将长期地质碳循环与短期生物碳循环联系起来的先决条件。
Soils comprise the largest terrestrial carbon (C) pool, containing both organic and inorganic C. Soil inorganic carbon (SIC) was frequently disregarded because (1) it is partly heritage from soil parent material, (2) it undergoes slow formation processes and (3) has very slow exchange with atmospheric CO2. The global importance of SIC, however, is reflected by the fact that SIC links the long-term geological C cycle with the fast biotic C cycle, and this linkage is ongoing in soils. Furthermore, the importance of SIC is at least as high as that of soil organic carbon (SOC) especially in semiarid and arid climates, where SIC comprises the largest C pool. Considering the origin, formation processes and morphology, carbonates in soils are categorized into three groups: geogenic carbonates (GC), biogenic carbonates (BC) and pedogenic carbonates (PC). In this review we summarize the available data and theories on forms and formation processes of PC and relate them to environmental factors. After describing the general formation principles of PC, we present the specific forms and formation processes for PC features and the possibilities to use them to reconstruct soil-forming factors and processes. The following PC are described in detail: earthworm biospheroliths, rhizoliths and calcified roots, hypocoatings, nodules, clast coatings, calcretes and laminar caps.The second part of the review focuses on the isotopic composition of PC: δ13C, Δ14C and δ18O, as well as clumped13C and18O isotopes known as Δ47. The isotopic signature of PC enables reconstructing the formation environment: the dominating vegetation (δ13C), temperature (δ18O and Δ47), and the age of PC formation (Δ14C). The uncertainties in reconstructional and dating studies due to PC recrystallization after formation are discussed and simple approaches to consider recrystallization are summarized.Finally, we suggest the most important future research directions on PC, including the anthropogenic effects of fertilization and soil management. In conclusion, PC are an important part of SIC that reflect the time, periods and formation processes in soils. A mechanistic understanding of PC formation is a prerequisite to predict terrestrial C stocks and changes in the global C cycle, and to link the long-term geological with short-term biological C cycles.