Research Questions and General Approach
Despite the undisputed importance of soils for the quality of ground- and surface water, we are still lacking the mechanistic understanding of the interacting biogeochemical processes that control the persistence of pesticides in soil. Project P6 therefore identifies and quantifies chemical, physical, and biological processes controlling pesticide turnover in soil to address three central research questions:
- Why do intrinsically biodegradable compounds (here pesticides) persist in soils under field conditions?
- Which physicochemical and microbial factors control sorption, biodegradation and leaching of pesticides (and their metabolites) and how are they interrelated?
- Which microbial and small-scale control mechanisms of pesticide turnover need to be considered in mechanistic and predictive pesticide fate models and what are the limits of model simplifications in terms of uncertainties?
In project P6, we combine field monitoring with targeted laboratory experiments and mechanistic modeling:
- to characterize the inventory of pesticides, other organic compounds as well as dissolved organic carbon and nitrogen species
- to quantify the biodegradation potential of the CAMPOS target compounds 2- methyl-4-chlorophenoxy acetic acid (MCPA), glyphosate and atrazine
- to identify physicochemical factors controlling the mobility and bioavailability of these target compounds
- to quantify concentration thresholds of pesticides triggering functional gene expression/ energy-limited growth of pesticide-degrading microorganisms
- to investigate how physiological responses of microorganisms (sensitivity to moisture and temperature, drought stress) affect biodegradation and leaching
- to assess how small-scale dynamics affect persistence and release of pesticides in soil
- to develop up-scaled expressions of pesticide turnover that integrate small-scale control mechanisms for implementation in vertical soil-crop models (Expert-N) in project P7
We have installed tension-controlled suction plate lysimeters at three representative soil monitoring stations in the Ammer catchment for intensive monitoring of pesticide leaching and stimulated field experiments. For detailed insights into control mechanisms of biodegradation, we have developed a gene-informed modeling approach and established qPCR protocols for quantifying gene transcripts of microbial degraders involved in the degradation of MCPA, glyphosate and atrazine.
Equifinality and sloppiness of biogeochemical models
Chavez Rodriguez L, Ingalls BP, Schwarz E., Streck T, Uksa M., Pagel H. (submitted): Gene-centric model approaches for accurate prediction of pesticide biodegradation in soils. ES&T
Martin P. R., Buchner D., Jochmann M. A., Haderlein S. B. (2020): Stable carbon isotope analysis of polyphosphonate complexing agents by anion chromatography coupled to isotope ratio mass spectrometry: method development and application. Anal Bioanal Chem 412: 4827–4835, doi: https://doi.org/10.1007/s00216-019-02251-w.
Nowak K.M., Miltner A., Poll C., Kandeler E., Streck T., Pagel H. (2020): Plant litter enhances degradation of the herbicide MCPA and increases formation of biogenic non-extractable residues in soil. Environ Int 142: 105867, doi: https://doi.org/10.1016/j.envint.2020.105867.
Pagel H., Kriesche B., Uksa M., Poll C., Kandeler E., Schmidt V., Streck T. (2020): Spatial Control of Carbon Dynamics in Soil by Microbial Decomposer Communities. Front Environ Sci doi: 10.3389/fenvs.2020.00002, doi: https://doi.org/10.3389/fenvs.2020.00002.
Subdiaga E., Harir M., Orsetti S., Hertkorn N., Schmitt-Kopplin P., Haderlein S. B. (2020): Preferential Sorption of Tannins at Aluminum Oxide Affects the Electron Exchange Capacities of Dissolved and Sorbed Humic Acid Fractions. Environ Sci Technol 54(3): 1837-1847, doi: https://doi.org/10.1021/acs.est.9b04733.
Wimmer B., Pattky M., Gulu Zada L., Meixner M., Haderlein S.B., Zimmermann H.-P., Huhn C. (2020): Capillary electrophoresis-mass spectrometry for the direct analysis of glyphosate: method development and application to beer beverages and environmental studies. Anal Bioanal Chem 2020 doi: https://doi.org/10.1007/s00216-020-02751-0.
Marschmann G.L., Pagel H., Kügler P., Streck T. (2019): Equifinality, sloppiness, and emergent structures of mechanistic soil biogeochemical models. Environ Model Softw 104518, doi: 10.1016/j.envsoft.2019.104518.
Gauglitz G., Wimmer B., Melzer T., Huhn C. (2018): Glyphosate analysis using sensors and electromigration separation techniques as alternatives to gas or liquid chromatography. Anal Bioanal Chem 410(3): 725–746, doi: https://doi.org/10.1007/s00216-017-0679-x.
Huhn C. (2018): More and enhanced glyphosate analysis is needed. Anal Bioanal Chem 410(13): 3041–3045, doi: https://doi.org/10.1007/s00216-018-1000-3.
Pinheiro M., Pagel H., Poll C., Ditterich F., Garnier P., Streck T., Kandeler E., Vieublé Gonod L. (2018): Water flow drives small scale biogeography of pesticides and bacterial pesticide degraders - A microcosm study using 2,4-D as a model compound. Soil Biol Biochem 127: 137–147, doi: https://doi.org/10.1016/j.soilbio.2018.09.024.
Wirsching J, Pagel H, Ditterich F, Uksa M., Werneburg M., Zwiener C., Berner D., Kandeler E., Poll C. (2020): Biodegradation of pesticides at the limit: kinetics and microbial substrate use at low concentrations. Front Microbiol 11: 2107, doi: https://doi.org/10.3389/fmicb.2020.0210
Khaliun Sukhbaatar (2018): Reaktion von Bodenmikroorganismen auf die Zugabe des Pestizids MCPA bei unterschiedlichen Bodenfeuchten
Erik Schwarz (2020): Elucidating the spatial control of microbial pesticide degradation in soil by model-based scenario analysis