Data for: The distribution of long-chain n-alkan-2-ones in peat can be used to infer past changes in pH

Long-chain n-alkan-2-ones are biomarkers ubiquitous in peat deposits, however, their paleoenvironmental significance lacks constraints. Here we evaluate the influence pH exerts on the occurrence of long-chain n-alkan-2-ones in peat. A comparison of the distribution in a collection (n= 65) of modern peat samples with different pH (pH values 4.4-8.6) from China demonstrates that their distribution is significantly different between acid and alkaline peat. This difference can be explained by the pH control on the conversion of n-alkan-2-one precursor compounds (n-alkanes and fatty acids). Transfer functions between pH and n-alkan-2-one ratios were established using linear and logarithmic regression models. We then applied these proxies to reconstruct variations of paleo-pH in the Dajiuhu peat sequence to identify the history of peatland acidification over the last 13 kyr. We find significant changes in paleo-pH during the deglaciation/early Holocene and related these to times of dry climate in the region. The drought-induced peat acidification is supported by observations from modern drying events in the peatland. We propose that long-chain n-alkan-2-ones in peats have potential to trace paleo-pH changes across the deglaciation and Holocene, although further research from different peatlands and time periods is still needed.

长链n-烷基-2-酮在泥炭沉积物中普遍存在，然而，其古环境意义尚无明确限制。本研究评估了pH对泥炭中长链n-烷基-2-酮出现的影响。通过将来自中国不同pH值（pH值范围为4.4-8.6）的65个现代泥炭样本的分布进行比较，发现其分布在不同酸性泥炭和碱性泥炭之间存在显著差异。这种差异可归因于pH对n-烷基-2-酮前体化合物（n-烷烃和脂肪酸）转化的控制作用。利用线性和对数回归模型建立了pH与n-烷基-2-酮比值之间的转换函数。随后，我们应用这些代理变量重建了大九湖泥炭序列的古pH变化，以识别过去13千年来泥炭地酸化的历史。我们发现，在冰后期/早期全新世期间古pH值发生了显著变化，并将其与该区域干燥气候的时期联系起来。泥炭地干旱引起的酸化得到了现代干旱事件的观测结果的支持。我们提出，泥炭中的长链n-烷基-2-酮具有追踪冰后期和全新世古pH变化的历史潜力，尽管仍需进一步研究不同泥炭地和时间段的相关内容。