Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream
Photochemical processing is an important way to transform terrestrial dissolved organic matter (DOM) but was rarely investigated by ultra-high resolution mass spectrometry. We performed an irradiation experiment with water from a shaded forest stream flowing into a lit reservoir. Bacterial activity...
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doaj-c544eac3b24042838ef2ee494b6f44572020-11-25T01:32:47ZengMDPI AGWater2073-44412020-01-0112233110.3390/w12020331w12020331Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested StreamChristin Wilske0Peter Herzsprung1Oliver J. Lechtenfeld2Norbert Kamjunke3Wolf von Tümpling4Department of River Ecology, Helmholtz Centre for Environmental Research—UFZ, Brückstraße 3a, 39114 Magdeburg, GermanyDepartment of Lake Research, Helmholtz Centre for Environmental Research—UFZ, Brückstraße 3a, 39114 Magdeburg, GermanyDepartment of Analytical Chemistry, Helmholtz Centre for Environmental Research—UFZ, Research Group BioGeoOmics, Permoserstr. 15, 04318 Leipzig, GermanyDepartment of River Ecology, Helmholtz Centre for Environmental Research—UFZ, Brückstraße 3a, 39114 Magdeburg, GermanyDepartment of River Ecology, Helmholtz Centre for Environmental Research—UFZ, Brückstraße 3a, 39114 Magdeburg, GermanyPhotochemical processing is an important way to transform terrestrial dissolved organic matter (DOM) but was rarely investigated by ultra-high resolution mass spectrometry. We performed an irradiation experiment with water from a shaded forest stream flowing into a lit reservoir. Bacterial activity explained only 1% of dissolved organic carbon (DOC) decline in a combined bacterial and photodegradation approach. Photodegradation decreased the DOC concentration by 30%, the specific ultraviolet (UV) absorption by 40%−50%, and fluorescence intensity by 80% during six days. The humification index (HIX) decreased whereas the fluorescence index (FI) did not change. Two humic-like components identified by parallel factor analysis (PARAFAC) of excitation−emission matrices followed the decrease of fluorescent DOM. Changes of relative peak intensities of Fourier transform-ion cyclotron resonance mass spectroscopy (FT-ICR MS) elemental formula components as a function of cumulated radiation were evaluated both by Spearman’s rank correlation and linear regression. The FT-ICR MS intensity changes indicate that high aromatic material was photochemically converted into smaller non-fluorescent molecules or degraded by the release of CO<sub>2</sub>. This study shows the molecular change of terrestrial DOM before the preparation of drinking water from reservoirs.https://www.mdpi.com/2073-4441/12/2/331photodegradationdocsuva<sub>254</sub>2d fluorescencehixft-icr msparafaclight-dark |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Christin Wilske Peter Herzsprung Oliver J. Lechtenfeld Norbert Kamjunke Wolf von Tümpling |
spellingShingle |
Christin Wilske Peter Herzsprung Oliver J. Lechtenfeld Norbert Kamjunke Wolf von Tümpling Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream Water photodegradation doc suva<sub>254</sub> 2d fluorescence hix ft-icr ms parafac light-dark |
author_facet |
Christin Wilske Peter Herzsprung Oliver J. Lechtenfeld Norbert Kamjunke Wolf von Tümpling |
author_sort |
Christin Wilske |
title |
Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream |
title_short |
Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream |
title_full |
Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream |
title_fullStr |
Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream |
title_full_unstemmed |
Photochemically Induced Changes of Dissolved Organic Matter in a Humic-Rich and Forested Stream |
title_sort |
photochemically induced changes of dissolved organic matter in a humic-rich and forested stream |
publisher |
MDPI AG |
series |
Water |
issn |
2073-4441 |
publishDate |
2020-01-01 |
description |
Photochemical processing is an important way to transform terrestrial dissolved organic matter (DOM) but was rarely investigated by ultra-high resolution mass spectrometry. We performed an irradiation experiment with water from a shaded forest stream flowing into a lit reservoir. Bacterial activity explained only 1% of dissolved organic carbon (DOC) decline in a combined bacterial and photodegradation approach. Photodegradation decreased the DOC concentration by 30%, the specific ultraviolet (UV) absorption by 40%−50%, and fluorescence intensity by 80% during six days. The humification index (HIX) decreased whereas the fluorescence index (FI) did not change. Two humic-like components identified by parallel factor analysis (PARAFAC) of excitation−emission matrices followed the decrease of fluorescent DOM. Changes of relative peak intensities of Fourier transform-ion cyclotron resonance mass spectroscopy (FT-ICR MS) elemental formula components as a function of cumulated radiation were evaluated both by Spearman’s rank correlation and linear regression. The FT-ICR MS intensity changes indicate that high aromatic material was photochemically converted into smaller non-fluorescent molecules or degraded by the release of CO<sub>2</sub>. This study shows the molecular change of terrestrial DOM before the preparation of drinking water from reservoirs. |
topic |
photodegradation doc suva<sub>254</sub> 2d fluorescence hix ft-icr ms parafac light-dark |
url |
https://www.mdpi.com/2073-4441/12/2/331 |
work_keys_str_mv |
AT christinwilske photochemicallyinducedchangesofdissolvedorganicmatterinahumicrichandforestedstream AT peterherzsprung photochemicallyinducedchangesofdissolvedorganicmatterinahumicrichandforestedstream AT oliverjlechtenfeld photochemicallyinducedchangesofdissolvedorganicmatterinahumicrichandforestedstream AT norbertkamjunke photochemicallyinducedchangesofdissolvedorganicmatterinahumicrichandforestedstream AT wolfvontumpling photochemicallyinducedchangesofdissolvedorganicmatterinahumicrichandforestedstream |
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