TY - JOUR

T1 - Elevated air carbon dioxide concentrations increase dissolved carbon leaching from a cropland soil

AU - Siemens, Jan

AU - Pacholski, A.

AU - Heiduk, Katia

AU - Giesemann, Anette

AU - Schulte, Ulrike

AU - Dechow, Rene

AU - Kaupenjohann, Martin

AU - Weigel, Hans-Joachim

PY - 2012/4/1

Y1 - 2012/4/1

N2 - Increasing leaching losses of carbon from soils due to accelerated weathering and increasing concentrations of dissolved carbon as a result of intensified soil respiration are suspected to provide a negative feedback on rising atmospheric CO 2 concentrations. We tested this hypothesis by studying concentrations of dissolved carbon and groundwater recharge at the Braunschweig free air carbon dioxide enrichment (FACE) experiment under winter wheat and winter barley. Dissolved carbon concentrations under elevated atmospheric CO 2 and ambient conditions were rather similar and not consistently higher under FACE. An analysis of δ 13C signatures suggested that dissolved organic and inorganic carbon contained 9-29% (DOC) and 26-49% (DIC) of "new" carbon originating from CO 2 added to the FACE rings. Dissolved inorganic carbon additionally contained 15-42% of carbonate-derived C. A 15% reduction in evapotranspiration under elevated CO 2 increased groundwater recharge by 60 mm or 55%, which was the main driver for an observed 81% increase in dissolved carbon leaching from 2.7 to 4.9 g C m -2 year -1 at 90 cm depth. Our results suggest that future changes of dissolved carbon leaching losses will be mainly governed by changes in climate and groundwater recharge and to a lesser extent by increasing dissolved carbon concentrations.

AB - Increasing leaching losses of carbon from soils due to accelerated weathering and increasing concentrations of dissolved carbon as a result of intensified soil respiration are suspected to provide a negative feedback on rising atmospheric CO 2 concentrations. We tested this hypothesis by studying concentrations of dissolved carbon and groundwater recharge at the Braunschweig free air carbon dioxide enrichment (FACE) experiment under winter wheat and winter barley. Dissolved carbon concentrations under elevated atmospheric CO 2 and ambient conditions were rather similar and not consistently higher under FACE. An analysis of δ 13C signatures suggested that dissolved organic and inorganic carbon contained 9-29% (DOC) and 26-49% (DIC) of "new" carbon originating from CO 2 added to the FACE rings. Dissolved inorganic carbon additionally contained 15-42% of carbonate-derived C. A 15% reduction in evapotranspiration under elevated CO 2 increased groundwater recharge by 60 mm or 55%, which was the main driver for an observed 81% increase in dissolved carbon leaching from 2.7 to 4.9 g C m -2 year -1 at 90 cm depth. Our results suggest that future changes of dissolved carbon leaching losses will be mainly governed by changes in climate and groundwater recharge and to a lesser extent by increasing dissolved carbon concentrations.

KW - Sustainability Science

KW - Ecosystems Research

KW - Carbon sequestration

KW - Dissolved inorganic carbon

KW - Dissolved organic carbon

KW - Free air carbon dioxide enrichment

KW - Net biome productivity

KW - Net ecosystem carbon balance

UR - http://www.scopus.com/inward/record.url?scp=84857638261&partnerID=8YFLogxK

U2 - 10.1007/s10533-011-9584-0

DO - 10.1007/s10533-011-9584-0

M3 - Journal articles

AN - SCOPUS:84857638261

VL - 108

SP - 135

EP - 148

JO - Biogeochemistry

JF - Biogeochemistry

SN - 1939-1234

IS - 1-3

ER -