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Controls on the soil solution partit...

Kothawala, Dolly N.

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Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils./
Author:	Kothawala, Dolly N.
Description:	202 p.
Notes:	Source: Dissertation Abstracts International, Volume: 71-12, Section: B, page: 7308.
Contained By:	Dissertation Abstracts International71-12B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NR66617
ISBN:	9780494666173

Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils.
Kothawala, Dolly N.

Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils. - 202 p.

Source: Dissertation Abstracts International, Volume: 71-12, Section: B, page: 7308.

Thesis (Ph.D.)--McGill University (Canada), 2009.

The soil-solution partitioning of dissolved organic carbon (DOC) within mineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is an estimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC).

ISBN: 9780494666173Subjects--Topical Terms:

545717
Biogeochemistry.

Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils.
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245 1 0 $a Controls on the soil solution partitioning of dissolved organic carbon and nitrogen in the mineral horizons of forested soils.
300 $a 202 p.
500 $a Source: Dissertation Abstracts International, Volume: 71-12, Section: B, page: 7308.
502 $a Thesis (Ph.D.)--McGill University (Canada), 2009.
520 $a The soil-solution partitioning of dissolved organic carbon (DOC) within mineral soil horizons is primarily controlled by processes of adsorption and desorption. These abiotic processes largely occur within a short equilibration time of seconds to minutes, which generally occur faster than microbial processes. To characterise the adsorption of DOC to mineral soils, I used the Langmuir adsorption isotherm, which holds several advantages to the commonly used linear initial mass (IM) isotherm. One advantage to using the Langmuir isotherm is an estimation of the maximum DOC adsorption capacity (Qmax). The Qmax estimates the number of remaining DOC binding sites available on the mineral soil particle surfaces. I modified the traditional Langmuir isotherm in order to estimate the DOC desorption potential of native soil organic matter (SOC).
520 $a Sorption characteristics were derived for a broad range of52 mineral soils collected from 17 soil profiles spanning across Canada from British Columbia to Quebec. Mineral horizons with the greatest Qmax included the Fe-enriched B horizons of acidic Podzols and Volcanic soils, followed by B horizons not enriched in Fe, followed by A and C horizons. Podzol B horizons were distinct from all other horizons due to significantly higher desorption potential. Soil properties predicting the adsorption characteristics of DOC also predicted the adsorption characteristics of dissolved organic nitrogen (DON). Adsorption of DOC and DON was tightly coupled (R 2 = 0.86), however the ratio of DOC:DON in the final equilibrium solution lowered for 48 out of 52 minerals horizons. These results suggest that DON may be slightly more mobile than DOC.
520 $a A short-term (32 day) incubation was perform to establish the fate of indigenous soil C, relative to newly adsorbed soil C to four mineral soils with different adsorption characteristics. Soil columns were leached periodically and sampled for DOC and CO2 production. Two Fe-enriched mineral horizons with high adsorption capacity released low amounts of old SOC, yet released almost all of the newly adsorbed SOC. In contrast, two B horizons without Fe-enrichment released greater amounts of old SOC, and retained a greater fraction of the newly adsorbed SOC than the Fe-enriched horizons. These results identify a contrast between the fate of indigenous and newly adsorbed SOC on mineral soils with differing Qmax.
520 $a The final component of this study examined changes to the molecular structure of DOC after equilibration with mineral soils. Multiple techniques were used to assess changes in the molecular composition of DOC, including the analysis of aromatic content by specific UV absorbance (SUVA) and fluorescence spectroscopy, analysis of molecular weight distribution (MWD) with high performance size exclusion chromatography (HPSEC) and functional group analysis with Fourier transform infra-red spectroscopy (FTIR). The solution phase DOC generally showed a reduced aromatic content, along with the removal of organic compounds with carboxyl groups. The MWD of DOC was reduced after equilibration to mineral soils, and the reduction in average molecular weight was related to the Qmax of mineral soils.
520 $a The various components of this thesis have contributed to the overall understanding of controls on the adsorption of DOC and DON species to mineral soils of the Canadian temperate and boreal forest.
590 $a School code: 0781.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Agriculture, Soil Science. $3 1017824
650 4 $a Environmental Sciences. $3 676987
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710 2 $a McGill University (Canada). $3 1018122
773 0 $t Dissertation Abstracts International $g 71-12B.
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791 $a Ph.D.
792 $a 2009
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NR66617