Groundwater controls on colloidal transport in forest stream waters

N Gottselig; J Sohrt; D Uhlig; V Nischwitz; M Weiler; W Amelung

doi:10.1016/j.scitotenv.2019.134638

Groundwater controls on colloidal transport in forest stream waters

Sci Total Environ. 2020 May 15:717:134638. doi: 10.1016/j.scitotenv.2019.134638. Epub 2019 Dec 5.

Authors

N Gottselig¹, J Sohrt², D Uhlig³, V Nischwitz⁴, M Weiler², W Amelung⁵

Affiliations

¹ Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, University of Bonn, Nussallee 13, 53115 Bonn, Germany. Electronic address: ngottsel@uni-bonn.de.
² Chair of Hydrology, Albert-Ludwigs-Universität Freiburg, Friedrichstraße 39, 79098 Freiburg, Germany.
³ GFZ German Research Centre for Geosciences, Section Earth Surface Geochemistry, Telegrafenberg, 14473 Potsdam, Germany; Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, IBG-3: Agrosphere, 52425 Jülich, Germany.
⁴ Forschungszentrum Jülich GmbH, Central Institute for Engineering, Electronics and Analytics (ZEA-3), 52425 Jülich, Germany.
⁵ Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, University of Bonn, Nussallee 13, 53115 Bonn, Germany; Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences, IBG-3: Agrosphere, 52425 Jülich, Germany.

PMID: 31837854
DOI: 10.1016/j.scitotenv.2019.134638

Abstract

Biogeochemical changes of whole catchments may, at least in part, be deduced from changes in stream water composition. We hypothesized that there are seasonal variations of natural nanoparticles (NNP; 1-100 nm) and fine colloids (<300 nm) in stream water, which differ in origin depending on catchment inflow parameters. To test this hypothesis, we assessed the annual dynamics of the elemental composition of NNP and fine colloids in multiple water compartments, namely in stream water, above and below canopy precipitation, groundwater and lateral subsurface flow from the Conventwald catchment, Germany. In doing so, we monitored meteorological and hydrological parameters, total element loads, and analyzed element concentrations of org C, Al, Si, P, Ca, Mn and Fe by Asymmetric Flow Field Flow Fractionation (AF⁴). The results showed that colloid element concentrations were < 5 µmol/L. Up to an average of 55% (Fe) of total element concentrations were not truly dissolved but bound to NNP and fine colloids. The colloid patterns showed seasonal variability with highest loads in winter. The presence of groundwater-derived colloidal Ca in stream water showed that groundwater mainly fed the streams throughout the whole year. Overall, the results showed that different water compartments vary in the NNP and fine colloidal composition making them a suitable tool to identify the streams NNP and fine colloid sources. Given the completeness of the dataset with respect to NNP and fine colloids in multiple water compartments of a single forest watershed this study adds to the hitherto underexplored role of NNP and fine colloids in natural forest watersheds.

Keywords: Field flow fractionation; Nanoparticles; Phosphorus; Rainfall; Soil leachate.