Thuile Bistarelli Lukas, Poyntner Caroline, Santín Cristina, Doerr Stefan Helmut, Talluto Matthew V, Singer Gabriel, Sigmund Gabriel
Institute of Ecology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
Institute of Microbiology, University of Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
ACS ES T Water. 2021 Jul 9;1(7):1648-1656. doi: 10.1021/acsestwater.1c00185. Epub 2021 Jun 25.
Wildfires produce large amounts of pyrogenic carbon (PyC), including charcoal, known for its chemical recalcitrance and sorption affinity for organic molecules. Wildfire-derived PyC can be transported to fluvial networks. Here it may alter the dissolved organic matter (DOM) concentration and composition as well as microbial biofilm functioning. Effects of PyC on carbon cycling in freshwater ecosystems remain poorly investigated. Employing in-stream flumes with a control versus treatment design (PyC pulse addition), we present evidence that field-aged PyC inputs to rivers can increase the dissolved organic carbon (DOC) concentration and alter the DOM composition. DOM fluorescence components were not affected by PyC. The in-stream DOM composition was altered due to leaching of pyrogenic DOM from PyC and possibly concurrent sorption of riverine DOM to PyC. Decreased DOM aromaticity indicated by a lower SUVA (-0.31 unit) and a higher pH (0.25 unit) was associated with changes in enzymatic activities in benthic biofilms, including a lower recalcitrance index (β-glucosidase/phenol oxidase), suggesting preferential usage of recalcitrant over readily available DOM by biofilms. The deposition of particulate PyC onto biofilms may further modulate the impacts of PyC due to direct contact with the biofilm matrix. This study highlights the importance of PyC for in-stream biogeochemical organic matter cycling in fire-affected watersheds.
野火会产生大量的热解碳（PyC），包括木炭，其以对有机分子的化学难降解性和吸附亲和力而闻名。源自野火的热解碳可以被输送到河流网络中。在那里，它可能会改变溶解有机物质（DOM）的浓度和组成，以及微生物生物膜的功能。热解碳对淡水生态系统中碳循环的影响仍未得到充分研究。通过采用具有对照与处理设计（热解碳脉冲添加）的河流水槽，我们提供了证据表明，向河流中输入经过野外老化的热解碳会增加溶解有机碳（DOC）的浓度并改变DOM的组成。DOM荧光成分不受热解碳的影响。河流中的DOM组成因热解碳中热解性DOM的淋溶以及河流DOM可能同时吸附到热解碳上而发生改变。较低的SUVA（-0.31单位）和较高的pH值（0.25单位）表明DOM芳香性降低，这与底栖生物膜中酶活性的变化有关，包括较低的难降解指数（β-葡萄糖苷酶/酚氧化酶），这表明生物膜优先利用难降解的DOM而非易利用的DOM。颗粒状热解碳在生物膜上的沉积可能会由于与生物膜基质的直接接触而进一步调节热解碳的影响。这项研究强调了热解碳对受火灾影响流域中河流生物地球化学有机物质循环的重要性。
