Dissolved organic matter (DOM) is a heterogeneous mixture of organic compounds that is produced through both microbial degradation and abiotic leaching of solid phase organic matter, and by a wide range of metabolic processes in algae and higher plants. DOM is ubiquitous throughout the hydrologic cycle and plays an important role in watershed management for drinking water supply as well as many aspects of aquatic ecology and geochemistry. Due to its wide-ranging effects in natural waters and analytical challenges, the focal research questions regarding DOM have varied since the 1920s. A standard catchment-scale model has emerged to describe the environmental controls on DOM concentrations. Modest concentrations of DOM are found in atmospheric deposition, large increases occur in throughfall and shallow soil flow paths, and variable concentrations in surface waters occur largely as a result of the extent to which hydrologic flow paths encounter deeper mineral soils, wetlands or shallow organic-rich riparian soils. Both production and consumption of DOM occur in surface waters but appear to frequently balance, resulting in relatively constant concentrations with distance downstream in most streams and rivers. Across biomes the concentration and composition of DOM in flowing waters is driven largely by soil processes or direct inputs to channels, but high levels can be found in streams and rivers from the tropics to the poles. Seven central challenges and opportunities in the study of DOM should frame ongoing research. These include maintaining or establishing long-term records of changes in concentrations and fluxes over time, capitalizing on the use of sensors to describe short-term DOM dynamics in aquatic systems, integrating the full carbon cycle into understanding of watershed and aquatic DOM dynamics, understanding the role of DOM in evasion of greenhouse gases from inland waters, unraveling the enigma of dissolved organic nitrogen, documenting gross versus net DOM fluxes, and moving beyond an emphasis on functional ecological significance to understanding the evolutionary significance of DOM in a wide range of environments.

溶解有机物 (DOM) 是有机化合物的异质混合物，通过微生物降解和固相有机物的非生物浸出，以及藻类和高等植物中的广泛代谢过程产生。DOM 在整个水文循环中无处不在，在饮用水供应的流域管理以及水生生态和地球化学的许多方面都发挥着重要作用。由于 DOM 在天然水体中的广泛影响和分析挑战，自 1920 年代以来，关于 DOM 的重点研究问题发生了变化。已经出现了一个标准的流域规模模型来描述对 DOM 浓度的环境控制。在大气沉降中发现 DOM 浓度适中，通过落差和浅层土壤流动路径大幅增加，地表水中的浓度变化主要是由于水文流动路径遇到更深的矿质土壤、湿地或浅层富含有机物的河岸土壤。DOM 的生产和消耗都发生在地表水中，但似乎经常平衡，导致在大多数溪流和河流的下游距离上相对恒定的浓度。在整个生物群系中，流动水中 DOM 的浓度和组成主要由土壤过程或直接输入渠道驱动，但在从热带到极地的溪流和河流中可以发现高水平。DOM 研究中的七个主要挑战和机遇应该构成正在进行的研究。这些包括维护或建立浓度和通量随时间变化的长期记录，