Flow and Reactivity Effects on Dissolved Organic Matter Transport in Soil Columns

Weigand, Harald; Totsche, Kai Uwe

doi:10.2136/sssaj1998.03615995006200050017x

Cited by 81 publications

(67 citation statements)

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“…DOC retention in the soil profile seems to be mostly abiotic sorption and depends on the specific mineral surface area, thus, soil texture and mineralogy (McDowell and Wood 1984;Yano et al 2005). Additionally, DOC sorption on mineral surfaces is kinetically limited, leading to lower sorption rates under high pore water velocity (Weigand and Totsche 1998). High soil water velocity is typical for sandy soils and has been shown by instantly increasing subsoil water content in the Arenosol (Kaltenborn) after rain events but not in the Vertisol (Mehrstedt, Fig.…”

Section: Soil Disturbance and Doc Leachingmentioning

confidence: 99%

Controls on fluxes and export of dissolved organic carbon in grasslands with contrasting soil types

2008

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Export of dissolved organic carbon (DOC) from grassland ecosystems can be an important C flux which directly affects ecosystem C balance since DOC is leached from the soil to the groundwater. DOC fluxes and their controlling factors were investigated on two grassland sites with similar climatic conditions but different soil types (Vertisol vs. Arenosol) for a 2.5-year period. Parts of both grasslands were disturbed by deep ploughing during afforestation. Contrary to what was expected, ploughing did not increase DOC export but surface soil DOC concentrations decreased by 28% (Vertisol) and 14% (Arenosol). DOC flux from the soil profile was negatively influences by the clay content of the soil with seven times larger DOC export in the clay-poor Arenosol (55 kg C ha -1 a -1 ) than in the clay-rich Vertisol (8 kg C ha -1 a -1 ). At the Arenosol site, highest DOC concentrations were measured in late summer, whereas in the Vertisol there was a time lag of several months between surface and subsoil DOC with highest subsoil DOC concentrations during winter season. DOC export was not correlated with soil organic carbon stocks. Large differences in 14 C concentrations of 22-40 pMC between soil organic carbon and DOC in the subsoil indicated that both C pools are largely decoupled. We conclude that DOC export at both sites is not controlled by the vegetation but by physicochemical parameters such as the adsorption capacity of soil minerals and the water balance of the ecosystem. Only in the acidic sandy Arenosol DOC export was a significant C flux of about 8% of net ecosystem production.

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Section: Soil Disturbance and Doc Leachingmentioning

confidence: 99%

Controls on fluxes and export of dissolved organic carbon in grasslands with contrasting soil types

2008

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“…Within soils, factors such as hydraulic conductivity and bypass flow capacity affect the concentration and flux of inorganic elements in a solution (Prendergast, 1995), and it is likely that DOC behaves in a similar manner (Radulivich et al, 1992). Weigand and Totsche (1998) have provided strong evidence that water flow rates through soil layers affect the fate of DOC. A recent analysis of stream discharge and DOM measurements from 30 forested watersheds in the eastern United States revealed the importance of hydrologic events in regulating the transport of DOC to downstream ecosystems (Raymond and Saiers, 2010).…”

Section: Doc Sorption/desorption Submodelmentioning

confidence: 99%

“…These parameters were established from Forest-DNDC (Li et al, 2000). The equation scales with clay content because the rate of sorption does not appear to be affected by hydrologic flux rates in sandy soils (Weigand and Totsche, 1998). In contrast to sorption flux, desorption flux appears to be driven by concentration gradients that increase with solution flow (Weigand and Tosche, 1998).…”

Section: Doc Sorption/desorption Submodelmentioning

confidence: 99%

Modeling dissolved organic carbon in temperate forest soils: TRIPLEX-DOC model development and validation

Peng

Moore

et al. 2014

Geosci. Model Dev.

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Abstract. Even though dissolved organic carbon (DOC) is the most active carbon (C) cycling in soil organic carbon (SOC) pools, it receives little attention from the global C budget. DOC fluxes are critical to aquatic ecosystem inputs and contribute to the C balance of terrestrial ecosystems, but few ecosystem models have attempted to integrate DOC dynamics into terrestrial C cycling. This study introduces a new process-based model, TRIPLEX-DOC, that is capable of estimating DOC dynamics in forest soils by incorporating both ecological drivers and biogeochemical processes. TRIPLEX-DOC was developed from Forest-DNDC, a biogeochemical model simulating C and nitrogen (N) dynamics, coupled with a new DOC process module that predicts metabolic transformations, sorption/desorption, and DOC leaching in forest soils. The model was validated against field observations of DOC concentrations and fluxes at white pine forest stands located in southern Ontario, Canada. The model was able to simulate seasonal dynamics of DOC concentrations and the magnitudes observed within different soil layers, as well as DOC leaching in the age sequence of these forests. Additionally, TRIPLEX-DOC estimated the effect of forest harvesting on DOC leaching, with a significant increase following harvesting, illustrating that land use change is of critical importance in regulating DOC leaching in temperate forests as an important source of C input to aquatic ecosystems.

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“…There is also evidence that water flow rate through soils affects the physical reactivity of DOC. In a laboratory experiment using goethitecoated sands, a 50% increase in pore water velocity led to an 18% decrease in the slope of the adsorption isotherm and an 83% increase in the desorption coefficient (Weigand and Totsche 1998).…”

Section: (Sorption Affinity) B (Desorption Parameter) Rsp (Reactimentioning

confidence: 99%

“…The equation scales with clay content because the rate of sorption does not appear to be affected by hydrologic flux rates in sandy soils (Weigand and Totsche 1998). In contrast to the sorption flux, the desorption flux is driven by concentration gradients and increases with solution flow (Weigand and Totsche 1998)…”

Section: (Sorption Affinity) B (Desorption Parameter) Rsp (Reactimentioning

confidence: 99%

Dissolved Organic Carbon in Terrestrial Ecosystems: Synthesis and a Model

2001

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The movement of dissolved organic carbon (DOC) through soils is an important process for the transport of carbon within ecosystems and the formation of soil organic matter. In some cases, DOC fluxes may also contribute to the carbon balance of terrestrial ecosystems; in most ecosystems, they are an important source of energy, carbon, and nutrient transfers from terrestrial to aquatic ecosystems. Despite their importance for terrestrial and aquatic biogeochemistry, these fluxes are rarely represented in conceptual or numerical models of terrestrial biogeochemistry. In part, this is due to the lack of a comprehensive understanding of the suite of processes that control DOC dynamics in soils. In this article, we synthesize information on the geochemical and biological factors that control DOC fluxes through soils. We focus on conceptual issues and quantitative evaluations of key process rates to present a general numerical model of DOC dynamics. We then test the sensitivity of the model to variation in the controlling parameters to highlight both the significance of DOC fluxes to terrestrial carbon processes and the key uncertainties that require additional experiments and data. Simulation model results indicate the importance of representing both root carbon inputs and soluble carbon fluxes to predict the quantity and distribution of soil carbon in soil layers. For a test case in a temperate forest, DOC contributed 25% of the total soil profile carbon, whereas roots provided the remainder. The analysis also shows that physical factors-most notably, sorption dynamics and hydrology-play the dominant role in regulating DOC losses from terrestrial ecosystems but that interactions between hydrology and microbial-DOC relationships are important in regulating the fluxes of DOC in the litter and surface soil horizons. The model also indicates that DOC fluxes to deeper soil layers can support a large fraction (up to 30%) of microbial activity below 40 cm.

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Flow and Reactivity Effects on Dissolved Organic Matter Transport in Soil Columns

Cited by 81 publications

References 0 publications

Controls on fluxes and export of dissolved organic carbon in grasslands with contrasting soil types

Controls on fluxes and export of dissolved organic carbon in grasslands with contrasting soil types

Modeling dissolved organic carbon in temperate forest soils: TRIPLEX-DOC model development and validation

Dissolved Organic Carbon in Terrestrial Ecosystems: Synthesis and a Model

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