Influence of different redox conditions and dissolved organic matter on pesticide biodegradation in simulated groundwater systems

AbstractThe molecular signature of dissolved organic matter (DOM) in groundwaters can be used as a tool when investigating the palaeohydrological response of groundwater systems in relation to changes in recharge environment, and also for examining groundwater compartmentalisation, mixing and transport at underground repositories for radioactive waste. The DOM in groundwaters from two compartmentalised bodies of groundwater of distinctly different origin within the Äspö Underground Research Laboratory (URL), Sweden and in Baltic seawater has been isolated using tangential flow ultrafiltration (TUF) and diafiltration. Recoveries of DOM ranged from 34.7 to 0.1 mg/L with substantial differences in the concentrations of the groundwaters collected only 120 m apart. Analysis by infrared spectroscopy (IR) and pyrolysisgas chromatography-mass spectrometry (Py-GC-MS) of the isolated DOM revealed that the groundwaters contained abundant alkylphenols which may represent heavily decomposed proteins or lignins originating from biopolymers contained within soils. The difference in the distribution and relative abundance of major pyrolysis products groups such as alkyphenols confirmed that the groundwater and Baltic seawater DOM samples were chemically distinct indicating minimal infiltration of marine groundwater derived by recharge from the Baltic or earlier Littorina Sea within the two compartmentalised groundwater bodies.

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Impacts of redox conditions on dissolved organic matter (DOM) quality in marine sediments off the River Rhône, Western Mediterranean Sea

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2020.02.001 ◽

2020 ◽

Vol 276 ◽

pp. 151-169 ◽

Cited By ~ 3

Author(s):

Shuchai Gan ◽

Frauke Schmidt ◽

Verena B. Heuer ◽

Tobias Goldhammer ◽

Matthias Witt ◽

...

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Mediterranean Sea ◽

Marine Sediments ◽

Western Mediterranean ◽

Redox Conditions ◽

Western Mediterranean Sea

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Soil Colloid Release Affected by Dissolved Organic Matter and Redox Conditions

Vadose Zone Journal ◽

10.2136/vzj2015.02.0026 ◽

2016 ◽

Vol 15 (3) ◽

pp. vzj2015.02.0026 ◽

Cited By ~ 21

Author(s):

Jing Yan ◽

Volha Lazouskaya ◽

Yan Jin

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Redox Conditions ◽

Soil Colloid

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Waterlogging and soil reduction affect the amount and apparent molecular weight distribution of dissolved organic matter in wetland soil: a laboratory study

Soil Research ◽

10.1071/sr16308 ◽

2018 ◽

Vol 56 (1) ◽

pp. 28 ◽

Cited By ~ 5

Author(s):

Asmaa Rouwane ◽

Malgorzata Grybos ◽

Isabelle Bourven ◽

Marion Rabiet ◽

Gilles Guibaud

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Humic Substances ◽

Apparent Molecular Weight ◽

Redox Condition ◽

Redox Conditions ◽

Wetland Soil ◽

Soil Redox ◽

Reducing Conditions

The release of dissolved organic matter (DOM) from wetland soils is an important pathway for the input of organic compounds into adjacent aquatic environments. In the present study we investigated, under controlled laboratory conditions, the quantity and quality of DOM released from a wetland soil subject to waterlogging and reducing conditions. Three soil redox conditions (oxic, moderately reducing and advanced reducing) were distinguished based on nitrate, ferrous ions and sulfate concentrations in soil solution. Under each redox condition, the quantity (dissolved organic carbon (DOC), humic substances and peptides plus proteins (P-PN) and quality (aromaticity; specific ultraviolet absorbance at 254 nm (SUVA254nm)) and apparent molecular weight (aMW) distribution) of DOM were investigated. The results showed that soil redox condition affects the amount and properties of mobilised DOM. The rate of DOM release and SUVA254 values were highest during the transition from oxic to moderately reducing conditions, whereas both stabilised during progression to advanced reducing conditions. In addition, the mobilised DOM is expected to be more reactive because of an increase in polar substituents in aromatic structures between oxic and moderately reducing conditions. During the development of moderately reducing conditions, dissolved humic substances increased significantly, whereas their aMW distribution (between 500 and 6000 ) remained constant for each of the three different redox conditions. In contrast, the quantity of dissolved P-PN remained low and steady under the three redox conditions, whereas the aMW distribution of protein-like and microbial by-product-like compounds decreased during the development of reducing conditions (aMW of compounds between 100 and >100 000).

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Analysis of the Three-Dimensional Fluorescence Spectroscopy Characteristics of Dissolved Organic Matter in Groundwater from a Subtropical Cave in Dry Season—Daxiao Cave in South China Karst

Water ◽

10.3390/w13243574 ◽

2021 ◽

Vol 13 (24) ◽

pp. 3574

Author(s):

Renkai Zhang ◽

Ziqi Liu ◽

Kangning Xiong ◽

Xiaoxi Lyu ◽

Chenpeng Hu ◽

...

Keyword(s):

Organic Matter ◽

Fluorescence Spectroscopy ◽

Dissolved Organic Matter ◽

Spectral Characteristics ◽

Three Dimensional ◽

Water System ◽

Dry Season ◽

Drip Water ◽

Groundwater Systems ◽

The Relationship

Groups in dissolved organic matter (DOM) emit fluorescence information at characteristic wavelengths when irradiated by excitation waves, which can reveal the geochemical behavior of dissolved organic matter in the environment and its sources, but there are few relevant studies in cave groundwater systems. In order to investigate the relationship between drip hydrochemistry characteristics and DOM in cave systems after subsurface leakage, in this study, from the perspective of dissolved organic matter in the karst cave water system, the groundwater in the dry season of Daxiao Cave was selected as the research object. Five drip points and one water pool (DX-1, DX-2, DX-3, DX-4, DX-5, and DX-C) in Daxiao Cave were monitored and consecutively sampled for four months. The parallel factor analysis method (PARAFAC), three-dimensional (3D) fluorescence parameters, and excitation-emission matrix fluorescence spectroscopy (EEM), combined with the hydrochemistry characteristics of the drip water and correlation analysis, were used to analyze the 3D fluorescence spectral characteristics of the DOM of the drip water of Daxiao Cave and their influencing factors. The results show that (1) the hydrochemistry type of the drip water in Daxiao Cave was within the Ca–Mg–HCO3 type, and Ca2+, Mg2+, and HCO3- were the dominant ions in Daxiao Cave; (2) the fluorescence fractions of drip water in dry season caves were dominated by C1 (humus-like), C2 (tryptophan-like), and C3 (tyrosine-like), and the fluorescence fractions of drip water DOM were controlled by protein fluorophores; (3) the DOM in the drip water of Daxiao Cave in the dry season was controlled in part by subsurface leakage and was largely the result of microbial degradation; and (4) the DOM of the drip water may be influenced by the chemical composition of the water, but the exact process is not clear.

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