compound-specific stable-isotope-analysis (d13C); terrestrial biogeochemistry; soil fractionation; land-use; aquatic biogeochemistry; plant biomarker; soil organic matter; microbial biomarker
Upadhayay H.R., Smith H.G., Griepentrog M., Bodé S., Bajracharya R.M., Blake W., Cornelis W., Boeckx P. (2018), Community managed forests dominate the catchment sediment cascade in the mid-hills of Nepal: A compound-specific stable isotope analysis, in Science of the Total Environment
, 637-638, 306-317.
Upadhayay H.R., Bodé S., Griepentrog M., Bajracharya R.M., Blake W., Cornelis W., Boeckx P. (2018), Isotope mixing models require individual isotopic tracer content for correct quantification of sediment source contributions, in Hydrological Processes
, 32, 981-989.
Upadhayay H.R., Bodé S., Griepentrog M., Huygens D., Bajracharya R.M., Blake W.H., Dercon G., Mabit L., Gibbs M., Semmens B.X., Stock B.C., Cornelis W., Boeckx P. (2017), Methodological perspectives on the application of compound-specific stable isotope fingerprinting for sediment source apportionment, in Journal of Soils and Sediments
, 17, 1537-1553.
Soils have a profound importance for human life, as they are essential to sustain food security and provide fundamental ecosystem functions. Humans are globally changing the environment with widespread changes in land-use, but it is however not clear how organic matter (OM) in soils reacts to the current change in environmental conditions. There is growing evidence that the stabilization of soil OM is not mainly controlled by its molecular structure, as previously thought, but by the environmental conditions. Furthermore recent evidence shows that soil OM is largely derived from microbial OM and does not mainly consist of plant-derived OM. These paradigm shifts in soil OM research also affect interpretations of aquatic biogeochemistry and there is a strong demand to transcend the boundaries of terrestrial and aquatic research communities. The sole application of plant biomarkers to quantify the transport of terrestrial OM into aquatic ecosystems is questioned by the fact that soil OM consists in large parts of microbial OM. However, microbial biomarkers have been rarely characterized in aquatic ecosystems and the transport of terrestrial OM in aquatic ecosystems might be greatly underestimated due to the over-reliance on plant-derived biomarkers as proxies for terrestrial OM inputs. The proposed project aims (1) to study the biogeochemical origin (plant versus microbial) of OM in terrestrial and aquatic ecosystems and (2) to investigate how different types of land-use relatively contribute to the transport of OM from terrestrial to aquatic ecosystems. Therefore, particle-size fractions of soils and river sediments from various land-use types will be analyzed for plant (n-alkanes) and microbial (amino sugars) biomarkers using state-of-the-art molecular and stable isotope (d13C) analysis of specific biomarkers. The combined isotope analysis of plant- and microbial-derived biomarkers in both soils and river sediments offers a unique tool to study the biogeochemical origin and composition of OM that gets transported from terrestrial to aquatic ecosystems. Furthermore, physical fractionation of soils and sediments will localize OM within the soil matrix and emphasize OM fractions that are most relevant for erosion and sedimentation processes. The proposed project will generate a comprehensive budget of plant and microbial biomarkers in the terrestrial and aquatic ecosystems of a watershed with different types of land-use. It will constrain the sources of soil OM eroded from different land-use types and provide novel information on the mechanisms that control the stabilization and destabilization of OM in eroding landscapes. It will furthermore help to clarify the relative contribution of microbial-derived OM to the transport of terrestrial OM into aquatic ecosystems. The proposed project links terrestrial and aquatic biogeochemistry and therefore helps to bridge knowledge across the boundaries of research communities.