Rivers, Lakes, Reservoirs, and Inland Seas
Pp. 107-119 (13)
Intensified agriculture, input of sewage and waste, as well as deforestation in
the 20th century in Europe caused a decline of river water quality and an increase in its
turbidity, and rapid terrestrialisation of lakes. The situation was improved by sewerages
and water purification plants, which, however, cannot retain all pollutants and toxins.
Among the problems are elevated nitrate concentrations, Hg, microplastics and waste
heat from power plants. Generally, immissions from mines, industry, and urban areas
have impaired hydrochemistry of rivers and lakes. Examples: Potassium mining
salinised the river Werra; unconventional oil development at Athabasca impaired
ambient catchments with toxic aerosols. Ecological and hydrological degradation of
very large lakes occurred due to the introduction of xenospecies to foster industrial fish
catch, input of acid mine drainage, poor sewage treatment, nearby overgrazing and
deforestation, and excess water abstraction from affluents. Washout of agricultural
nutrients and inappropriate disposal of sewage effected vertical shoaling of the world's
largest anoxic, sulphidic water body in the Black Sea. The global trend of lakes
towards CO2 supersaturation results from enhanced input of dissolved organic carbon
(DOC), promoting microbial respiration. In remote glacial lakes, climate warming has
caused reduction of ice coverage and of permafrost, and effected substantial alteration
of lacustrine hydrochemistries. A generalisation of effects of anthropogenic activities to
the flow variability of large rivers is not possible. However, engineering, freshwater
withdrawal, and extraction of sand and gravel fostered river bed erosion and caused
delta starvation, subsidence, and coastal erosion. Hydrochemical studies recognised
severe pollution of parts of surface waters in China. Radioactive contamination of
surface waters occurred near nuclear plants and repositories.
Anoxia, Contamination, Desiccation, Ecosystem change, Erosion,
Eutrophication, Immissions, Irrigation, Reactive nitrogen, River engineering,
Surface water, Terrestrialisation, Warming, Water abstraction, Water balance,
Water demand, Water pollution, Water protection, Water quality, Xenospecies.
Environmental Geology, Munich, Germany.