Divergent effect of silicon on greenhouse gas production from reduced and oxidized peat organic matter
Divergent effect of silicon on greenhouse gas production from reduced and oxidized peat organic matter
复制标题
DOI：
10.1016/j.geoderma.2020.114916
复制
发表时间：
2021-01-09
期刊：
影响因子：
6.1
通讯作者：
Schaller, Joerg
中科院分区：
文献类型：
--
作者：
Hoemberg, Annkathrin;Broder, Tanja;Schaller, Joerg
泥炭地储存了全球土壤碳（C）储量的30%。在这些系统中，泥炭C的分解取决于环境参数，例如地下水位和微生物呼吸的电子受体的相应可用性。由于后者，潜在的泥炭分解也取决于材料是否最初被氧化或还原之前分解experiments.Recent研究揭示了硅（Si）的泥炭分解的重要性。大量的生物硅被发现在泥炭地，特别是在minerotrophic沼泽，硅的重要性禾本科和分解各自的凋落物已被广泛讨论。此外，据报道，Si的可用性影响磷（P）与铁（Fe）的结合，从而影响分解进行的条件。然而，在不同的初始氧化还原条件下，硅对泥炭温室气体产生的影响在很大程度上是未知的。因此，我们打算测试不同的初始电子受体微生物呼吸的可用性，如铁Fe。我们进行了两个培养实验与初始氧化和还原泥炭有机质（OM）的温室气体产生的影响。我们假设Si可以从Fe矿物中动员P，从而增加微生物活性，并导致更高的二氧化碳（CO2）和甲烷（CH4）生产率。使用这两种不同的材料，我们研究了初始氧化还原条件如何改变Si的效果。作为铁的主要形式，无论是铁的氢氧化物或亚铁矿物（硫化物、碳酸盐）对于与Si的相互作用是重要的，我们进一步假设，与仅含亚铁的初始还原泥炭相比，在含亚铁的初始氧化泥炭中，Si的影响应该更强。对于使用先前氧化的材料的孵育实验，Si的添加增加了孔隙水中的P浓度，产生了更多的二氧化碳。甲烷的发病是强得多，比没有添加硅，表明更快的呼吸速率的电子受体消耗更快。我们解释这是由更多的P刺激微生物活性，也由硅对微生物活性和甲烷生成的直接影响。以前减少OM的孵化没有表现出任何影响的呼吸过程中，可能是由于没有铁Fe phase.In结论，有一个明显的差异，除了在分解的影响，以前氧化相比，长期减少OM，只有氧化泥炭OM或泥炭与铁Fe相呈现明显的Si效果。因此，氧化还原条件和铁Fe的有效性是Si对OM分解和养分有效性影响的主要控制因素。在永久还原条件下，在没有铁Fe相的情况下，可以预期Si的影响很小。
Peatlands store about 30% of the global soil carbon (C) stock. The decomposition of peat C in these systems depends on environmental parameters - such as water table levels and corresponding availability of electron acceptors for microbial respiration. Due to the latter, potential peat decomposition depends also on whether the material is initially oxidized or reduced prior to decomposition experiments.Recent studies revealed the importance of silicon (Si) for peat decomposition. High amounts of biogenic Si were found in peatlands, in particular in minerotrophic fens, and the importance of Si for graminoids and decomposability of respective litter has been widely discussed. Furthermore, the availability of Si was reported to influence the binding of phosphorus (P) to iron (Fe) and thereby the conditions under which decomposition proceeds. Yet the influence of Si on greenhouse gas production in peat under different initial redox conditions is largely unknown. Therefore, we intended to test the effect of Si on greenhouse gas production under different initial electron acceptor availabilities for microbial respiration, such as the availability of ferric Fe.We conducted two incubation experiments with initially oxidized and reduced peat organic matter (OM). We hypothesized that Si can mobilize P from Fe minerals, which increases microbial activity, and leads to higher production rates of carbon dioxide (CO2) and methane (CH4). Using the two different materials, we studied how initial redox conditions would modify effects of Si. As the predominant form of Fe as either ferric Fe-(oxy)hydroxides or as ferrous Fe minerals (sulfides, carbonates) is important for interaction with Si, we further hypothesized that Si effects should be stronger in initially oxidized peat in presence of ferric Fe, compared to initially reduced peat with ferrous Fe only.For incubation experiments using formerly oxidized material the Si addition increased P concentrations in the pore water, and more CO2 was produced. The onset of methanogenesis was much stronger with than without addition of Si, indicating a more rapid depletion of electron acceptors by faster rates of respiration. We explain this by more P being available stimulating microbial activity, and also by a direct effect of Si on microbial activity and methanogenesis. The incubation of formerly reduced OM did not show any effects of Si on respiration processes, presumably due to the absence of ferric Fe phases.In conclusion, there was a clear difference in the effect of Si addition on decomposition of formerly oxidized compared to long term reduced OM, with only oxidized peat OM or peat with ferric Fe phases present showing clear Si effects. Consequently, redox conditions and availability of ferric Fe are a main control for Si effects on OM decomposition and nutrient availability. Little effects of Si can be expected under permanently reducing conditions and in absence of ferric Fe phases.