School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK; School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK.
School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK.
Sci Total Environ. 2022 Jun 25;827:154105. doi: 10.1016/j.scitotenv.2022.154105. Epub 2022 Feb 24.
Recent research has highlighted the importance of dissolved organic matter (DOM) for ecosystem function and because of this paradigm shift, it has become crucial to not only quantify its contribution to river nutrient loads but also to characterise its composition. There has been a significant research effort utilising optical methods, such as fluorescence and UV-Vis spectrophotometry, in order to start exploring DOM character. However, these methods still lack the granularity to understand the chemical composition at the molecular level, which is vital to properly understanding its functional role in freshwater ecosystems. As a direct result, there has been a shift towards including molecular-scale analyses to investigate the in-stream processing of the material. Alongside this, recent methodological advancements, particularly in mass spectrometry are opening new opportunities for probing one of the most complex environmental mixtures. However, in order to fully exploit these opportunities, it is key that the way that samples are collected, processed and stored is considered carefully such that sample integrity is maintained. There are additional challenges when collecting water samples for analysis at molecular scale, for example the ultra-low concentrations of individual compounds within DOM means that the samples are sensitive to contamination. This paper discusses current sample collection, processing and storage protocols for this C, N and P quantification and characterisation in freshwaters, and proposes a new standardised protocol suitable for both nutrient fraction quantification and molecular scale analyses, based on method development and testing undertaken in our UK Natural Environment Research Council large grant programme, characterising the nature, origins and ecological significance of Dissolved Organic Matter IN freshwater Ecosystems (DOMAINE).
最近的研究强调了溶解有机质（DOM）对生态系统功能的重要性，由于这种范式转变，不仅要量化其对河流养分负荷的贡献，还要对其组成进行特征描述，这一点变得至关重要。已经有大量研究利用荧光和紫外-可见分光光度法等光学方法来开始探索 DOM 的特征。然而，这些方法仍然缺乏理解分子水平化学组成的粒度，这对于正确理解其在淡水生态系统中的功能作用至关重要。因此，已经转向包括分子尺度分析，以研究物质在河流中的处理过程。与此同时，最近的方法学进展，特别是在质谱方面，为研究物质的流内处理提供了新的机会。然而，为了充分利用这些机会，关键是要仔细考虑样品的采集、处理和储存方式，以保持样品的完整性。在分子尺度上采集水样进行分析时还存在其他挑战，例如 DOM 中单个化合物的超低浓度意味着样品容易受到污染。本文讨论了当前用于淡水 C、N 和 P 定量和特征描述的水样采集、处理和储存方案，并根据在我们英国自然环境研究理事会大型资助计划中进行的方法开发和测试，提出了一种新的标准化方案，该方案既适合养分分定量，也适合分子尺度分析，用于描述淡水生态系统中溶解有机物质的性质、来源和生态意义（DOMAINE）。
