Properties of fluorescent dissolved organic matter in the Gironde Estuary
Properties of fluorescent dissolved organic matter in the Gironde Estuary
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DOI：
10.1016/j.orggeochem.2009.03.002
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发表时间：
2009-06-01
影响因子：
3
通讯作者：
Parlanti, E.
中科院分区：
文献类型：
--
作者：
Huguet, A.;Vacher, L.;Parlanti, E.
由于天然水中有机物质的异质性、复杂性和低浓度，水生溶解有机物（DOM）特性的分离、表征和研究仍然是一个挑战。基于其与污染物相互作用的能力，从而改变污染物的运输和生物利用度，DOM 在环境方面引起了人们的关注。这项工作的目的是更好地描述吉伦特河口（法国西南部）的 DOM。河口是大陆和大西洋之间的交换区，决定着有机和无机物质从大陆环境向海洋环境的转移。在 2002 年和 2006 年的三次航行中，沿河口采集了多个样本。使用激发发射矩阵 (EEM) 光谱法（一种允许直接分析水样的敏感技术）对这些样本进行了分析。荧光 DOM 和溶解有机碳 (DOC) 在该河口系统中的表现并不保守，即有机物质没有经历从河口上游到下游的简单稀释。指出了 DOC 含量的季节性变化，而 DOM 荧光的季节性变化很少。通过确定两个荧光指数——腐殖化指数（HIX）和近期本地贡献指数（BIX），进一步评估了河口的 DOM 来源和加工过程。通过应用这些指数，可以评估腐殖化的相对程度（HIX）和自养生产力（BIX）。根据荧光和DOC结果，根据盐度（S）将河口分为三个区域，并以特定的DOM为特征：（i）低盐度（S < 5）和高悬浮颗粒物浓度的浑浊区域，其中α'和α荧光团的强度增加，这是类腐殖质化合物的特征。 (ii) 河口中部区域 (5 < S < 25)，其特征是自养生产力低，含有严重降解的有机物质，如 BIX 值低和 HIX 值高所示。 (iii) 盐度较高的区域 (S > 25)，其特征是自养生产力增加和显着的海洋影响，并分别与 BIX 和 HIX 的高值和低值相关。 HIX 和 BIX 指数被证明是轻松定义和分类河口水域 DOM 特征的有用工具。 (C) 2009 Elsevier Ltd. 保留所有权利。
The isolation, characterization and study of the properties of aquatic dissolved organic matter (DOM) still represent a challenge because of the heterogeneity, complexity and low concentration of organic material in natural waters. Based on its ability to interact with contaminants and thus to modify their transport and bioavailability, DOM is of interest for environmental purposes. The objective of this work was to better characterize DOM in the Gironde Estuary (southwestern France). The estuary represents an exchange zone between the continent and the Atlantic Ocean and conditions the transfer of organic and inorganic substances from the continental to the oceanic environment. Several samples were collected along the estuary during three cruises in 2002 and 2006. They were analysed using excitation-emission matrix (EEM) spectroscopy, a sensitive technique that allows direct analysis of water samples. Fluorescent DOM and dissolved organic carbon (DOC) did not behave conservatively in this estuarine system, i.e. the organic material did not undergo simple dilution from the upstream to the downstream part of the estuary. A seasonal variability in DOC content was pointed out, whereas few seasonal variations in DOM fluorescence were observed. DOM sources and processing in the estuary were further evaluated by determining two fluorescence indices - the humification index (HIX) and the index of recent autochthonous contribution (BIX). By applying these indices, the relative degree of humification (HIX) and autotrophic productivity (BIX) could be assessed. Based on the fluorescence and DOC results, the estuary was divided into three zones depending on salinity (S) and characterized by specific DOM: (i) A turbid zone of low salinity (S < 5) and high suspended particulate matter concentration with increase in the intensities of the alpha' and alpha fluorophores, characteristic of humic-like compounds. (ii) A mid-estuarine zone (5 < S < 25) characterized by low autortrophic productivity and containing strongly degraded organic material, as shown by the low values of BIX and high values of HIX. (iii) A higher salinity area (S > 25) characterized by increased autortrophic productivity and a marked marine influence, and associated with high and low values of BIX and HIX, respectively. The HIX and BIX indices were shown as useful tools for readily defining and classifying DOM characteristics in estuarine waters. (C) 2009 Elsevier Ltd. All rights reserved.