INRAE, UR RiverLy, 5 rue de la Doua, CS 20244, 69625, Villeurbanne Cedex, France.
INRAE, UR RiverLy, 5 rue de la Doua, CS 20244, 69625, Villeurbanne Cedex, France.
J Environ Manage. 2021 Aug 15;292:112775. doi: 10.1016/j.jenvman.2021.112775. Epub 2021 May 21.
Fluvial suspended particulate matter (SPM) fluxes transport large amounts of contaminants that can affect water quality and river ecosystems. To better manage these inputs in river systems, it is essential to identify SPM and sediment sources. Many studies have applied a fingerprinting method based on using metals integrated into a numerical mixing model to estimate source contributions in a watershed. Most fingerprinting studies use contemporary SPM to trace historical inputs, whereas their metal concentrations were modified over time due to anthropogenic inputs. Moreover, total concentrations of these properties are subject to change due to diagenetic processes occurring in stored sediments. The aim of this study was to assess the relevance of using the non-reactive fraction of metals (i.e. metals and metalloids) in fingerprinting studies to estimate the historical contributions of SPM tributary inputs in a sediment core. To assess metal concentrations in the 'conservative' (i.e. non-reactive) fraction, SPM (samples of sources) and sediment core layers (targeted sediments) were subjected to total mineralization and soft extraction, and the non-reactive fraction was obtained by calculating the difference between the two extractions. This approach was applied on a sediment core from the Upper Rhône River (France), using geochemical signature in contemporary SPM of three major tributaries. We showed that the non-reactive fraction retains a higher number of metals in the range test for the deepest layers, which are characterized by significant anthropogenic inputs. Through apportionment modelling using Monte Carlo simulation, we demonstrated that the tributary contributions computed using the non-reactive fraction are more consistent with historical flood and water flow data and have lower uncertainties than with the total fraction. Working with the non-reactive fraction made it possible to decipher historical inputs of SPM using contemporary SPM samples. This approach enables robust identification of sub-catchment areas liable to provide large quantities of SPM. The non-reactive fraction can be used in a variety of environmental conditions and at various spatial and temporal scales to provide a robust quantification of sediment sources.
河流悬浮颗粒物 (SPM) 通量输送大量污染物，这些污染物可能影响水质和河流生态系统。为了更好地管理河流系统中的这些输入，识别 SPM 和沉积物来源至关重要。许多研究应用了一种基于将金属整合到数值混合模型中的示踪方法，以估计流域内的源贡献。大多数示踪研究使用现代 SPM 来追踪历史输入，而它们的金属浓度随着时间的推移由于人为输入而发生变化。此外，由于存储沉积物中发生的成岩作用，这些特性的总浓度可能会发生变化。本研究的目的是评估在示踪研究中使用金属的非反应部分（即金属和类金属）来估计 SPM 支流输入的历史贡献的相关性。为了评估“保守”（即非反应性）部分的金属浓度（即金属和类金属），对 SPM（来源样品）和沉积物芯层（目标沉积物）进行了总矿化和软提取，通过计算两种提取之间的差异获得非反应性部分。该方法应用于法国上罗纳河（Upper Rhône River）的一个沉积物芯，使用三个主要支流的现代 SPM 的地球化学特征。我们表明，在范围测试中，非反应性部分在最深层保留了更多的金属，这些层的特征是存在大量人为输入。通过使用蒙特卡罗模拟进行分配建模，我们证明，使用非反应性部分计算的支流贡献与历史洪水和水流数据更一致，并且不确定性比总分数更低。使用非反应性部分进行研究使得使用现代 SPM 样本解析 SPM 的历史输入成为可能。这种方法能够可靠地识别可能提供大量 SPM 的子流域。非反应性部分可用于各种环境条件以及不同的空间和时间尺度，以提供对沉积物来源的稳健量化。
