Limited effects of land use on soil dissolved organic matter chemistry as assessed by excitation-emission fluorescence spectroscopy and molecular weight fractionation

Abstract. Dissolved organic matter (DOM) is an important resource for microbes, thus affecting the whole stream metabolism. The factors influencing its chemical composition and thereby also its bio-availability are complex and not thoroughly understood. We hypothesized that the whole stream metabolism itself can affect the DOM composition and that the coupling of both is influenced by seasonality and different land use forms. We tested this hypothesis in a comparative study on two pristine forestry streams and on two non-forestry streams. The investigated streams were located in the Harz Mountains (Central Europe, Germany). The whole stream metabolism was measured with a classical two station oxygen change technique and the variability of DOM with fluorescence spectroscopy. We take also into account the geochemical and geophysical characteristic of each stream. All streams were clearly net heterotrophic, whereby the non-forestry streams showed a higher primary production in general, which was correlated with irradiance and with the total phosphorus concentration. The whole stream metabolism but also the chromophoric DOM (CDOM) showed distinct seasonal patterns. We detected three CDOM component groups (C1, C2, C3) by the use of the parallel-factor-analysis (PARAFAC) and found temporarily variable, typical component fingerprints (C1:C2, C1:C3, C3:C2) for CDOM originated from forestry streams and from non-forestry streams. Based on comparative literature studies and correlation analysis with different indices, we demonstrate that two of the components are clearly from terrigenous sources (C1, C3) and one is rather autochthonously (C2) derived. The whole CDOM matrix was dominated by humic like, high molecular-weight substances, followed by humic like, fulfic acids, low molecular-weight substances, and with minor amounts of amino-acids and proteins. We showed for the first time a correlation between the gross primary production (GPP) and the autochthonously derived, low molecular weight DOM. The amount of autochthonously produced DOM increased overall with increasing GPP, as indicated by a tight, positive correlation between the fluorescence index (FI, R2 = 0.84) or C2 (R2= 0.48) and the ratio of GPP and the daily community respiration (CR24). This study showed for the first time the linkage between whole stream metabolism and DOM composition, based on a new integrated approach. We demonstrated that this relationship is influenced by seasonality and different land use forms. These complex mechanisms lead to typical DOM fingerprints for streams pass through the different land use forms.

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Molecular-Weight-Fractionation Characteristics and Coagulation Behaviors of Biorecalcitrant Dissolved Organic Matter and Colorants in Cassava Distillery Wastewater

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.8b00287 ◽

2018 ◽

Vol 57 (12) ◽

pp. 4442-4451 ◽

Cited By ~ 3

Author(s):

Yu Chen ◽

Ming Zhang ◽

Li Xie ◽

Zhou Wang ◽

Qi Zhou

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Distillery Wastewater ◽

Molecular Weight Fractionation

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Effects of land use and nutrients on the characteristics of dissolved organic matter in the Nanchong Section of Jialing River, China in December 2019

Water Science & Technology Water Supply ◽

10.2166/ws.2021.307 ◽

2021 ◽

Author(s):

Liuqing Zhang ◽

Xiaohua Zhu ◽

Xing Huang ◽

Chaorong Liu ◽

Yan Yang

Keyword(s):

Land Use ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Absorption Coefficient ◽

Aquatic Ecosystems ◽

Direct Evidence ◽

Chromophoric Dissolved Organic Matter ◽

Jialing River ◽

Parallel Factor ◽

Effects Of Land Use

Abstract Chromophoric dissolved organic matter (CDOM) in aquatic ecosystems can reflect the impacts of human activities on the carbon-cycling process. However, direct evidence of the combined effect of land use and anthropogenic nutrients on CDOM characteristics in river ecosystems is limited. Herein, we collected water samples from 18 sites in the Nanchong section of Jialing River in December 2019 to elucidate how the land use and nutrients affect the source and composition of CDOM through parallel factor (PARAFAC) analysis of excitation–emission matrices (EEMs). First, the absorption coefficient a254 (r2=0.29, p<0.01) and three fluorescence components (humic-like C1 and C2 and protein-like C3) (r2=0.31–0.37, p<0.01) significantly increased with increased urban area, and the four parameters were higher in the urban than in the suburb (p<0.05). The correlation between small CDOM molecule and cropland land was positive (p<0.01). Second, the increase in nutrient levels increased the a254 (r2=0.84 and 0.33, p<0.01) and three fluorescence components (r2=0.30–0.84, p<0.01 or p<0.05). Third, allochthonous CDOM were prevalent in the Nanchong Section of Jialing River, and the proportions of C1 and C2 were 42 and 41%, respectively. Our findings indicated that the variability of source and composition of CDOM significantly depended on urbanization and increased nutrients in the Nanchong Section of Jialing River.

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Bioavailability of riverine dissolved organic matter in three Baltic Sea estuaries and the effect of catchment land use

Biogeosciences ◽

10.5194/bg-10-6969-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 6969-6986 ◽

Cited By ~ 82

Author(s):

E. Asmala ◽

R. Autio ◽

H. Kaartokallio ◽

L. Pitkänen ◽

C. A. Stedmon ◽

...

Keyword(s):

Molecular Weight ◽

Land Use ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Agricultural Land ◽

Natural Forest ◽

Bacterial Growth Efficiency ◽

Co2 Fluxes ◽

Natural Forests ◽

Degradation Rates

Abstract. The microbial degradation of dissolved organic carbon and nitrogen (DOC, DON) was studied in three Finnish boreal estuaries with contrasting land use patterns (Kiiminkijoki – natural forest and peatland; Kyrönjoki – agricultural; Karjaanjoki – mixed/urban). Bioassays of 12–18 d long durations were used in 3 seasons at in situ temperatures. Besides the bulk parameters, a suite of dissolved organic matter (DOM) quality parameters were also investigated, including colored DOM (CDOM), fluorescent DOM and the molecular weight of DOM. Bioavailable DOC and DON pools varied significantly between the estuaries, from 7.9 to 10.6% and from 5.5 to 21.9%, respectively. DOM originating from the catchment dominated by natural forests and peatlands (Kiiminkijoki) had the lowest DOC and DON degradation rates, as well as the lowest proportions of biodegradable DOC and DON. A greater proportion of agricultural land in the catchment increased the bioavailability of DON, but not the bioavailability of DOC (Kyrönjoki). Additionally, DOM quality varied significantly between the estuaries, and DOM originating from the agricultural Kyrönjoki catchment sustained higher DOC and DON degradation rates and higher bacterial growth efficiency (BGE) compared to those of the natural forest and peat dominated Kiiminkijoki catchment. The quality of DOM, indicated by differences in CDOM, fluorescent DOM and molecular weight, varied between estuaries with differing land use and was concluded to be major driver of BGE of these systems and thereafter to the microbial CO2 fluxes from the estuaries. The differences in BGE resulted in a 5-fold difference in the calculated daily bacterial CO2 emissions between the study's estuaries due to bacterial activity, ranging from 40 kg C d−1 in the Karjaanjoki estuary to 200 kg C d−1 in the Kyrönjoki estuary. Lower DOC:DON ratios, smaller molecular weight and higher CDOM absorption spectral slope values of DOM resulted in higher proportion of the initial DOC and DON being transferred to microbial growth and therefore to the pelagic food web. The pristine, peatland and forest-dominated Kiiminkijoki catchment had the lowest BGE, and therefore proportionally highest CO2 fluxes.

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Effects of Land Use on the Degradability of Dissolved Organic Matter in Three Watersheds of the Plum Island Sound Estuary

Biological Bulletin ◽

10.1086/bblv189n2p256 ◽

1995 ◽

Vol 189 (2) ◽

pp. 256-257 ◽

Cited By ~ 4

Author(s):

A. G. Uhlenhopp ◽

J. E. Hobbie ◽

J. J. Vallino

Keyword(s):

Land Use ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Effects Of Land Use ◽

Island Sound

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Bioavailability of riverine dissolved organic matter in three Baltic Sea estuaries and the effect of catchment land-use

Biogeosciences Discussions ◽

10.5194/bgd-10-9819-2013 ◽

2013 ◽

Vol 10 (6) ◽

pp. 9819-9865 ◽

Cited By ~ 2

Author(s):

E. Asmala ◽

R. Autio ◽

H. Kaartokallio ◽

L. Pitkänen ◽

C. A. Stedmon ◽

...

Keyword(s):

Molecular Weight ◽

Land Use ◽

Organic Matter ◽

Dissolved Organic Matter ◽

Agricultural Land ◽

Natural Forest ◽

Bacterial Growth Efficiency ◽

Co2 Fluxes ◽

Natural Forests ◽

Degradation Rates

Abstract. The microbial degradation of dissolved organic carbon and nitrogen (DOC, DON) was studied in three boreal estuaries with contrasting land use patterns (Kiiminkijoki – natural forest and peatland; Kyrönjoki – agricultural; Karjaanjoki – mixed/urban). Bioassays conducted for 12–18 days were used in 3 seasons at in situ temperatures. Besides the bulk parameters, a suite of dissolved organic matter (DOM) quality parameters were investigated, including colored DOM (CDOM), fluorescent DOM and the molecular weight of DOM. Bioavailable DOC and DON pools varied significantly between the estuaries, from 7.9% in Kiiminkijoki to 10.6% in Karjaanjoki and from 5.5% in Kiiminkijoki to 21.9% in Kyrönjoki, respectively. DOM originating from catchment dominated by natural forests and peatlands had the lowest DOC and DON degradation rates, as well as the lowest proportions of biodegradable DOC and DON. A greater proportion of agricultural land in the catchment increased the bioavailability of DON, but not the bioavailability of DOC. Also DOM quality varied significantly between the estuaries, and DOM originating from the agricultural Kyrönjoki catchment sustained higher DOC and DON degradation rates and higher bacterial growth efficiency (BGE) compared to those of the natural forest and peat dominated Kiiminkijoki catchment. The quality of DOM, indicated by differences in CDOM, fluorescent DOM and molecular weight, varied between estuaries with differing land use and was concluded to be major driver of BGE of these systems and thereafter to the microbial CO2 fluxes from the estuaries. The differences in BGE resulted in a 5-fold differences in the calculated daily bacterial CO2-emissions between the study estuaries due to bacterial activity, ranging from 40 kg C d–1 in Karjaanjoki estuary to 200 kg C d–1 in Kyrönjoki estuary. Two of the study systems (Karjaanjoki, mixed land use; Kyrönjoki, intensive agriculture) in which the DOM pool had lower DOC : DON ratio, smaller molecular weight and higher CDOM absorption spectral slope values resulted in higher proportion of the initial DOC and DON being transferred to microbial growth and therefore to the pelagic food web. The pristine, peatland and forest-dominated Kiiminkijoki catchment had the lowest BGE, and therefore proportionally highest CO2 fluxes. The slope coefficient S275–295 was a good proxy of molecular weight across estuaries and seasons, and also for different diagenetic stages of DOM during biological degradation.

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