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Anthropogenic influences on a small catchment as shown by dissolved fertilizers, chloride and carbonates: The Bucher Landgraben (Northern Bavaria)

Anne Batz1, Simone Hintze1, Robert van Geldern1, Johannes Barth1
1 Lehrstuhl angewandte Geologie, Geozentrum Nordbayern

P 6.1 in Groundwater, soil and surface water interactions

The aim of this study was to investigate effects of land use in a small agricultural catchment, the “Bucher Landgraben” north of Nuremberg (Bavaria). Preliminary results highlighted influences of human inputs by agriculture and roads. Further influences by industry and an airport in the catchment area were not investigated in this study. For this purpose two sampling campaigns were carried out, the first in February 2013 and the second in March 2013. During each campaign 11 to 14 sampling points were visited and the following in situ parameters were measured: temperature, pH, conductivity, alkalinity, redox potential and oxygen concentration. Major ions (Li+, Na+, K+, Ca2+, Mg2+, NH4+, F-, Cl-, NO3-, NO2-, SO42- and PO43-), oxygen and hydrogen stable isotope composition of water (δ18O, δ2H), stable carbon isotope ratio of dissolved inorganic (δ13CDIC), dissolved organic carbon (, δ13CDOC), and particulate organic carbon (δ13CPOC) were analysed in the laboratory.

One of the key findings of this study was how fertilizers influence the carbon cycle and weathering. For instance nitrate concentrations ranged from 4.8 to 310.0 mg/L. The latter value occurred at the transition from a forested- to an agriculturally used area and most likely reflects influences by fertilizers. Chloride concentrations showed an opposite trend and were influenced by road salt in the source area with values up to 379 mg/L. Much lower values around 60 mg/L were found in the agriculturally used sections of the stream. Nitrate values correlated with calcium and magnesium contents. This corresponds to findings by Gandois et al. (2011), Perrin et al. (2008) and Semhi et al. (2000).



 

Gandois L., Perrin A. S., Propst A. (2011): Impact of nitrogenous fertiliser-induced proton release on cultivated soils with contrasting carbonate contents: A column experiment. Geochimica et Cosmochimica Acta 75 (1185-1198)

Perrin A. S., Probst A., Probst J. L. (2008): Impact of nitrogenous fertilizers on carbonate dissolution in small agricultural catchments: Implications for weathering CO2 uptake at regional and global scales. Geochimica et Cosmochimica Acta 72 (3105-3123)

Semhi K., Amiotte Suchet P., Clauer N., Probst J. L. (2000): Impact of nitrogen fertilizers on the natural weathering-erosion processes and fluvial transport in the Garonne basin. Applied Geochemistry 15 (865-878)

last modified 2014-05-13