Peat decomposition records in three pristine ombrotrophic bogs in southern Patagonia
Peat decomposition records in three pristine ombrotrophic bogs in southern Patagonia
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DOI：
10.5194/bg-9-1479-2012
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发表时间：
2012-01-01
期刊：
影响因子：
4.9
通讯作者：
Knorr, K. H.
中科院分区：
文献类型：
--
作者：
Broder, T.;Blodau, C.;Knorr, K. H.
在古气候和地球化学研究方面，对巴塔哥尼亚南部的营养型沼泽进行了研究，但对这些沼泽中有机质分解的认识有限。因此，我们通过傅里叶变换红外（FTIR）测量固体泥炭，C/N比，δ C-13和δ N-15同位素测量三个沼泽地点的泥炭腐殖化程度。泥炭分解总体上随深度增加而增加，但存在明显的小尺度变化，反映了控制分解因素的波动。C/N变化范围在40 ~ 120之间，与ftir衍生的腐殖化指数呈极显著相关（R-2 > 0.55, p < 0.01）。在目前以泥炭藓为主的立地，腐解程度最低。泥炭在最干燥的地点分解最强烈，目前形成泥炭的植被产生的难降解有机物质较少，可能是由于高海雾沉降的施肥作用。在火山灰层附近，泥炭的分解也超前，表明火山灰沉积促进了分解。δ C-13在泥炭中的值为26.5 +/- 2 /千，与分解指数部分相关，而δ N-15在泥炭中的值在零附近变化，与任何分解指数没有一致的关系。DOM浓度部分与碳氮比相关，部分与FTIR衍生指数相关。它们与泥炭的分解程度没有决定性的联系。相对于固相，DOM在C-13和N-15中富集，这可能是由于这些贫氮环境中的多次微生物修饰和N的再循环。综上所述，C/N比、δ C-13值和FTIR光谱的深度剖面似乎反映了影响分解的环境条件的变化，如沼泽湿度，但主要受场地特定因素的影响，并进一步受到灰沉降和可能的海喷输入的影响。
Ombrotrophic bogs in southern Patagonia have been examined with regard to paleoclimatic and geochemical research questions but knowledge about organic matter decomposition in these bogs is limited. Therefore, we examined peat humification with depth by Fourier Transformed Infrared (FTIR) measurements of solid peat, C/N ratio, and delta C-13 and delta N-15 isotope measurements in three bog sites. Peat decomposition generally increased with depth but distinct small scale variation occurred, reflecting fluctuations in factors controlling decomposition. C/N ratios varied mostly between 40 and 120 and were significantly correlated (R-2 > 0.55, p < 0.01) with FTIR-derived humification indices. The degree of decomposition was lowest at a site presently dominated by Sphagnum mosses. The peat was most strongly decomposed at the driest site, where currently peat-forming vegetation produced less refractory organic material, possibly due to fertilizing effects of high sea spray deposition. Decomposition of peat was also advanced near ash layers, suggesting a stimulation of decomposition by ash deposition. Values of delta C-13 were 26.5 +/- 2 parts per thousand in the peat and partly related to decomposition indices, while delta N-15 in the peat varied around zero and did not consistently relate to any decomposition index. Concentrations of DOM partly related to C/N ratios, partly to FTIR derived indices. They were not conclusively linked to the decomposition degree of the peat. DOM was enriched in C-13 and in N-15 relative to the solid phase probably due to multiple microbial modifications and recycling of N in these N-poor environments. In summary, the depth profiles of C/N ratios, delta C-13 values, and FTIR spectra seemed to reflect changes in environmental conditions affecting decomposition, such as bog wetness, but were dominated by site specific factors, and are further influenced by ash deposition and possibly by sea spray input.