Soil Science, Univ. of Rostock, Justus-von-Liebig-Weg 6, 18051, Rostock, Germany.
Canadian Light Source Inc., Saskatoon, Saskatchewan, S7N 5A8, Canada.
J Environ Qual. 2021 Nov;50(6):1364-1380. doi: 10.1002/jeq2.20284. Epub 2021 Sep 25.
About 91,300 ha of peatlands has been rewetted in western Europe since the mid-1990s. Still, it is unknown how long-term rewetting alters the dissolved organic matter (DOM) concentration, molecular composition, and functional groups. We examined these DOM characteristics in three peatland types subjected to 47- to 231-yr drainage and 18- to 24-yr rewetting to address this knowledge gap. Cold water-extractable DOM was characterized by pyrolysis field ionization mass spectrometry (Py-FIMS) and X-ray absorption near-edge structure (XANES) spectroscopy. The dissolved organic carbon (DOC) concentration in the rewetted forest peatland was 2.7 times higher than in the drained forest peatland. However, rewetting decreased the DOC concentrations by 1.5 and 4 times in the coastal peatland and percolation mire, respectively, compared with their respective drained peatlands at the topsoil horizons. The Py-FIMS analysis revealed that all nine DOM compound classes' relative abundances differed between the rewetted and drained forest peatland with the lower relative abundances of the labile DOM compound classes in the rewetted forest peatlands. However, most DOM compound classes' relative abundances were similar between the rewetted and drained coastal peatlands and percolation mires. The XANES also revealed nine carbon and seven nitrogen functional groups with no apparent differences between the two contrasting management practices. The influence of drainage and rewetting on DOC concentration and molecular composition depends on peatland type, drainage period, rewetting intensity, and peat degradation status that should be considered in future research for understanding DOM transformation and transportation from degraded and restored peatland ecosystems.
自 20 世纪 90 年代中期以来，西欧已有约 91300 公顷的泥炭地得到了再湿润。然而，长期再湿润如何改变溶解有机物质（DOM）的浓度、分子组成和官能团仍不得而知。为了填补这一知识空白，我们研究了三种泥炭地类型，这些泥炭地经历了 47 至 231 年的排水和 18 至 24 年的再湿润。采用热解场离子化质谱（Py-FIMS）和 X 射线吸收近边结构（XANES）光谱法对冷水可提取 DOM 进行了特征分析。再湿润森林泥炭地的溶解性有机碳（DOC）浓度是排水森林泥炭地的 2.7 倍。然而，与排水泥炭地相比，再湿润分别使沿海泥炭地和渗流泥沼的表层土壤的 DOC 浓度降低了 1.5 倍和 4 倍。Py-FIMS 分析表明，与排水森林泥炭地相比，再湿润和排水森林泥炭地之间所有 9 种 DOM 化合物类别的相对丰度均有所不同，再湿润森林泥炭地中不稳定 DOM 化合物类别的相对丰度较低。然而，再湿润和排水沿海泥炭地以及渗流泥沼之间大多数 DOM 化合物类别的相对丰度相似。XANES 还揭示了 9 种碳和 7 种氮官能团，这两种对比管理实践之间没有明显差异。排水和再湿润对 DOC 浓度和分子组成的影响取决于泥炭地类型、排水期、再湿润强度和泥炭退化状况，这应在未来的研究中加以考虑，以了解退化和恢复的泥炭地生态系统中 DOM 的转化和运输。
