Rivers of North Rhine Westphalia revisited.

• Published in: Applied Geochemistry
• Main Authors: Stögbauer, A., Strauss, H., Arndt, J., Marek, V., Einsiedl, F., Geldern, R.V.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon Press 2008
• Subjects: river; North Rhine Westphalia; revisitation; tracing changes; river chemistry; Carbonic acid
• Online Access: https://push-zb.helmholtz-muenchen.de/frontdoor.php?source_opus=2351; https://doi.org/10.1016/j.apgeochem.2008.06.030

Three rivers in North-Rhine Westphalia, Germany, were investigated for their hydrochemical properties including their stable isotopic composition of water (d2H, d18O) and dissolved river compounds (d13CDIC, d34SSO4 and d18OSO4, and d15NNO3 and d18ONO3). The study focused on two objectives: an assessment of potential sources for river solutes (anthropogenic vs. natural sources), and the quantification of changes in river chemistry over the past 15 a (for the rivers Lippe and Ruhr). Decreasing concentrations were found for most of those river constituents that are commonly linked to anthropogenic activities, such as , [Cl-], [K+], and [Na+]. An observed increase in for the river Lippe reflects most likely varying discharges from mining activities. Variations in the isotopic composition of water display the influence of ocean water (river Ems) or of evaporation that occurred either in channels (river Ems), in reservoirs (river Ruhr) or due to the use of river water for cooling purposes (river Lippe). d13CDIC values around -11‰ point to carbonate dissolution by carbonic acid as the major source for dissolved inorganic C. Modifications of this average d13CDIC resulted from enhanced agricultural use, sewage inputs, and gas exchange with the atmosphere in reservoirs and channels. The isotopic composition of dissolved reveals atmospheric deposition and sulphide oxidation as its major sources. Sulphate from sulphide oxidation in parts reflects the local geology (river Ruhr); in the Kreidebecken leaching of sulphide seems to be linked to agriculture and drainage (rivers Lippe and Ems). However, introduced from mining activities into the Lippe and the Ems does not alter the isotopic composition of riverine , despite rather high discharges. Nitrogen and O isotopes reveal that manure and sewage are major sources of NO3 in most parts of the river Ruhr. Only a single value from the headwaters displays the signature of soil NO3. Downstream increasing d15NNO3 and d18ONO3 values (both by 2‰ on average) point to denitrification ...