ANATOMY OF POLLUTION - RIVERS OF NORTH-RHINE-WESTPHALIA, GERMANY

North Rhine-Westphalia, the most industrialized and densely populated state of Germany, is drained by six major tributaries of the Rhine: th e Sieg, Wupper, Ruhr, Erft, Emscher, and Lippe. The first four drain p redominantly catchments with Phanerozoic siliciclastic rocks, while th e latter two dewater Cretaceous carbonate basins. Together, the rivers account for similar to 11 percent of the Rhine water, and they reflec t various stages of pollution, from a moderately polluted Sieg and Ruh r to the heavily damaged Emscher. The delta(18)O(H2O) of -8.5 +/- 1.5 permil SMOW suggests that summer recharge into local aquifers is the m ain source of water in these rivers. Down-stream, the water becomes en riched in O-18, by similar to 2 permil, due to low altitude precipitat ion and because of evaporation, particularly in artificial lakes. Howe ver thermal fractionation, when water is utilized for cooling in power stations and smelters, also contributes to this trend. State-wide, an d down-stream within rivers, the increasing pollution levels are chara cterized by rising salt concentrations (from normal riverine values up to a third of seawater), by up to two orders of magnitude CO2 overpre ssures, oxygen depletion, and enhanced nutrient concentrations. The de lta(13)C(DIC) demonstrate that microbial respiration of C-org in soil/ groundwater systems accounts for about 50 to 100 percent of the entire DIG, with the higher values typical of more polluted ecosystems. Evas ion of gaseous CO2 into the atmosphere and microbial nitrification are the most important processes for the riverine aquatic cycles of carbo n and nitrogen, resulting in more advanced dissipation of CO2 and NH4 in the less polluted ecosystems. Denitrification may fuel generation of some ''excess'' CO2 only in the highly polluted ecosystems, such as the Emscher.