J Environ Qual. 2019 Mar;48(2):233-235. doi: 10.2134/jeq2019.02.0002c.
Natural organic matter (NOM) is ubiquitous on the Earth surface and influences every biogeochemical reaction wherever it is present, and its impact on reactions varies with its abundance, structure, and chemistry. Because of decades of field and laboratory studies conducted on NOM in different environments, we are moving away from treating it as a black box to developing molecular structure-based approaches in investigations of soil, sediment, and aquatic systems and are beginning to make major advances in the detailed understanding of the molecular and structural characteristics of NOM, which in turn are helping in deciphering the biochemical processes involved in its evolution in the environment. Yet, many questions remain: How does NOM exist in different soil and aquatic environments? How should we obtain NOM from a sample, and does the isolated NOM represent the NOM in a sample? Do the geochemical reactions explored with extracted NOM represent the reality? How can we study NOM in situ? Here I present a synopsis of critical perspectives on the state of NOM research and a commentary on the reviews and debate presented in this special section on the NOM nomenclature, extraction procedures, and studies involving NOM in different environmental processes.
天然有机物（NOM）在地球表面无处不在，影响着它存在的每一个生物地球化学反应，其对反应的影响因丰度、结构和化学性质而异。由于几十年来在不同环境中对 NOM 进行的野外和实验室研究，我们正在摆脱将其视为黑箱的做法，转而采用基于分子结构的方法来研究土壤、沉积物和水生系统，并开始在详细了解 NOM 的分子和结构特征方面取得重大进展，这反过来又有助于破译其在环境中演化所涉及的生化过程。然而，仍有许多问题悬而未决：NOM 在不同的土壤和水生环境中是如何存在的？我们应该如何从样品中获取 NOM，分离出的 NOM 是否代表样品中的 NOM？用提取的 NOM 进行的地球化学反应是否代表实际情况？我们如何在现场研究 NOM？在这里，我对 NOM 研究现状提出了一些关键观点的概述，并对本专题中关于 NOM 命名、提取程序以及不同环境过程中涉及 NOM 的研究的评论和辩论进行了评论。
