Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento–San Joaquin River Basin, California

Sickman, James O.; DiGiorgio, Carol; Davisson, M. Lee; Lucero, D. M.; Bergamaschi, Brian A.

doi:10.1007/s10533-009-9391-z

Cited by 65 publications

(61 citation statements)

References 44 publications

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“…In Australia, the reconversion of coastal wetlands for agricultural and urban purposes was without effects on stream DOM, the latter being characterized by a chemical composition typical of former wetland ecosystems (Petrone et al 2011). On considering that mobilization of older DOM with increasing human disturbance is a globally consistent pattern (Evans et al 2007;Sickman et al 2010;Butman et al 2015), the contrasting observations reported above suggest that the net effect on DOM chemical structure can vary widely across catchments due to the interplay of several processes. Indeed, OM cycling in soils is highly complex and depends on numerous parameters such as soil chemical and structural properties, soil fauna, environmental conditions (climate, hydrology) or vegetation cover, and similar management practices can have contrasting effects on OM depending on local conditions as several of soil properties are modified at the same time (Chantigny 2003;Ogle et al 2005).…”

Section: Discussionmentioning

confidence: 96%

“…Indeed, OM cycling in soils is highly complex and depends on numerous parameters such as soil chemical and structural properties, soil fauna, environmental conditions (climate, hydrology) or vegetation cover, and similar management practices can have contrasting effects on OM depending on local conditions as several of soil properties are modified at the same time (Chantigny 2003;Ogle et al 2005). In addition to soil/SOM properties and agricultural practices, land use history, native vegetation and timing of SOM stabilization after land reconversion are additional drivers that will contribute to determine stream DOM composition in agricultural landscapes (Sickman et al 2010;Petrone et al 2011;Yamashita et al 2011).…”

Section: Discussionmentioning

confidence: 99%

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Effects of human land use on the terrestrial and aquatic sources of fluvial organic matter in a temperate river basin (The Meuse River, Belgium)

et al. 2017

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The impact of human activities on the concentrations and composition of dissolved organic matter (DOM) and particulate organic matter (POM) was investigated in the Walloon Region of the Meuse River basin (Belgium). Water samples were collected at different hydrological periods along a gradient of human disturbance (50 sampling sites ranging from 8.0 to 20,407 km 2 ) and during a 1.5 year monitoring of the Meuse River at the city of Liège. This dataset was completed by the characterization of the DOM pool in groundwaters. The composition of DOM and POM was investigated through elemental (C:N ratios), isotopic (d 13 C) and optical measurements including excitation emission matrix fluorescence with parallel factor analysis (EEM-PARAFAC). Land use was a major driver on fluvial OM composition at the regional scale of the Meuse Basin, the composition of both fluvial DOM and POM pools showing a shift toward a more microbial/algal and less plant/soil-derived character as human disturbance increased. The comparison of DOM composition between surface and groundwaters demonstrated that this pattern can be attributed in part to the transformation of terrestrial sources by agricultural practices that promote the decomposition of soil organic matter in agricultural lands and subsequent microbial inputs in terrestrial sources. In parallel, human land had contrasting effects on the autochthonous production of DOM and POM. While the in-stream generation of fresh DOM through biological activity was promoted in urban areas, summer autochthonous POM production was not influenced by land use. Finally, soil erosion by agricultural management practices favored the transfer of terrestrial organic matter via the particulate phase. Stable isotope data suggest that the hydrological transfer of terrestrial DOM and POM in humanimpacted catchment are not subject to the same controls, and that physical exchange between these two pools of organic matter is limited.

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Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

Effects of human land use on the terrestrial and aquatic sources of fluvial organic matter in a temperate river basin (The Meuse River, Belgium)

et al. 2017

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“…The production and leaching of DOC in terrestrial ecosystems affects the concentration, composition and age of DOC in aquatic systems (Raymond and Bauer 2001;Sickman et al 2010;Tipping et al 2010). The origin and quality of DOC as well as the dynamics of DOC concentrations in terrestrial ecosystems have therefore an impact on DOC concentrations in rivers and lakes (Evans et al 2007;Roulet and Moore 2006).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of dissolved organic 14C in throughfall and soil solution of a Norway spruce forest

2010

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Dissolved organic carbon (DOC) is an important component of the C cycle in forest ecosystems, but dynamics and origin of DOC in throughfall and soil solution are yet poorly understood. In a 2-year study, we analyzed the radiocarbon signature of DOC in throughfall and soil solution beneath the Oa horizon and at 90 cm depth in a Norway spruce forest on a Podzol soil. A two-pool mixing model revealed that throughfall DOC comprised mainly biogenic C, i.e. recently fixed C, from canopy leaching and possibly other sources. The contribution of fossil DOC from atmospheric deposition to throughfall DOC was on average 6% with maxima of 8-11% during the dormant season. In soil solution from the Oa horizon, DO 14 C signature was highly dynamic (range from -8% to ?103%), but not correlated with DOC concentration. Radiocarbon signatures suggest that DOC beneath the Oa horizon originated mainly from occluded and mineral associated organic matter fractions of the Oa horizon rather than from the Oi or Oe horizon. Relatively old C was released in the rewetting phase following a drought period in the late summer of 2006. In contrast, the DO 14 C signature indicated the release of younger C throughout the humid year 2007. In soil solutions from 90 cm depth, DO 14 C signatures were also highly dynamic (-127% to ?3%) despite constantly low DOC concentrations. Similar to the Oa horizon, the lowest DO 14 C signature at 90 cm depth was found after the rewetting phase in the late summer of 2006. Because of the variation in the DO 14 C signatures at this depth, we conclude that DOC was not equilibrated with the surrounding soil, but also originated from overlaying soil horizons. The dynamics of DO 14 C in throughfall and soil solution suggest that the sources of DOC are highly variable in time. Extended drought periods likely have a strong influence on release and translocation of DOC from relatively old and possibly stabilized soil organic matter fractions. Temporal variations as well as the input of fossil DOC needs to be considered when calibrating DOC models based on DO 14 C signatures.

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“…Soil tillage breaks up soil organic matter (SOM) aggregates and can result in strong microbial processing of SOM within these aggregates (Ewing et al, 2006). This may result in release of aged DOM previously bound to such SOM to freshwater ecosystems and, in fact, a high age of fluvial DOC was found in a study of US agricultural catchments (Sickman et al, 2010). Furthermore, nitrogen and phosphorus fertilizer addition to soils in intensive farming may promote higher microbial activity and result in higher release of DOM from SOM.…”

Section: Effects Of Farming Intensity On Fluvial Dom Qualitymentioning

confidence: 99%

“…These different effects could be a result of differences in catchment size, climate, land use history, sampling strategy and agricultural management (Stanley et al, 2012). We propose that in small catchments, intensive agriculture results in increased DOC concentrations and loads in the draining freshwater systems, since increased microbial activity and anthropogenic soil disturbance by tilling can release previously inert DOC from the soil matrix (Balesdent et al, 2000;Sickman et al, 2010;Ewing et al, 2006). However, most studies to date were undertaken in larger catchments or in catchments with a mix of catchment sizes, where this effect may be obscured by in-stream processing of agricultural DOC (Graeber et al, 2012b).…”

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confidence: 99%

Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments

Graeber

Goyenola

Meerhoff

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Dissolved organic matter (DOM) is an important factor in aquatic ecosystems, which is involved in a large variety of biogeochemical and ecological processes, and recent literature suggests that it could be strongly affected by agriculture in different climates. Based on novel monitoring techniques, we investigated the interaction of climate and agriculture effects on DOM quantity and quality. To examine this, we took water samples over 2 years in two paired intensive and extensive farming catchments in each of Denmark (temperate climate) and Uruguay (subtropical climate). We measured dissolved organic carbon (DOC) and nitrogen (DON) concentrations and DOC and DON molecular fractions with size-exclusion chromatography. Moreover, we characterized DOM quality with absorbance and fluorescence measurements, as well as parallel factor analysis (PARAFAC). We also calculated the DOC and DON loads based on daily discharge measurements, as well as measured precipitation and air temperature. The fluvial DOM in the catchments in Uruguay was characterized by higher temporal variability of DOC and DON loads which were clearly to a higher temporal variability of precipitation and a DOM composition with rather plant-like character relative to the Danish catchments. Moreover, we found a consistently higher temporal variability of DOC and DON loads in the intensive farming catchments than in the extensive farming catchments, with highest temporal variability in the Uruguayan intensive farming catchment. Furthermore, the composition of DOM exported from the intensive farming catchments was consistently complex and always related to microbial processing in both Denmark and Uruguay. This was indicated by low C : N ratios, several spectroscopic DOM composition indices and PARAFAC fluorescence components. We propose that the consistent effect of intensive farming on DOM composition and the temporal variability of DOC and DON loads is related to similarities in the management of agriculture, which may have widescale implications for fluvial DOM composition, as well as related ecological processes and biogeochemical cycles.

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Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento–San Joaquin River Basin, California

Cited by 65 publications

References 44 publications

Effects of human land use on the terrestrial and aquatic sources of fluvial organic matter in a temperate river basin (The Meuse River, Belgium)

Effects of human land use on the terrestrial and aquatic sources of fluvial organic matter in a temperate river basin (The Meuse River, Belgium)

Dynamics of dissolved organic 14C in throughfall and soil solution of a Norway spruce forest

Interacting effects of climate and agriculture on fluvial DOM in temperate and subtropical catchments

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