2.9 Salinisation of inland waters (Heike Zimmermann-Timm)
Salinisation of inland waters: Salinisation is caused by natural factors (e.g. the soil types of catchment areas, atmospheric deposition and climate) and by anthropogenic activities (e.g. agriculture and mining). Some of the consequences are an increase of salt content, and the enrichment of single toxic ions in soils and waters. Aquatic organisms of single species are adapted to freshwater, marine and brackish environments; they use different energy-consuming mechanisms to regulate the ion concentrations. With an increase in salinisation the number of organisms increases but there is a decrease in diversity. Extremely saline environments are dominated by micro-organisms; this is the reason why we find relatively short food chains, low turnover rates and differences in matter flux in these environments. Nutrient-rich environments with low oxygen concentrations result. Investigations of artificially salted rivers showed that desalinisation is possible if the causes of the salinisation are halted – this means in many cases the implementation of technical developments (e.g. site adapted irrigation measures in agriculture; leaching procedures in mining).