Lost in translation: the German literature on freshwater salinization

Abstract

Human activities have globally increased and altered the ion concentration of freshwater ecosystems. The proliferation of potash mines in Germany (especially intense in the early 1900s) constitutes a good example of it. The effluents and runoff coming from potash mines led to extreme salt concentrations (e.g. 72 g l^-1 of total salt content, approx. 149 mS cm^-1) in surrounding rivers and streams, causing ecosystem degradation (e.g. massive algal blooms and fish kills). This promoted scientific research that was mostly published in German, thereby being neglected by the wide scientific community. Here, the findings of the German literature on freshwater salinization are discussed in the light of current knowledge. German studies revealed that at similar ion concentrations potassium (K⁺) can be the most toxic ion to freshwater organisms, whereas calcium (Ca²⁺) could have a toxicity ameliorating effect. Also, they showed that salinization could lead to biodiversity loss, major shifts in the composition of aquatic communities (e.g. dominance of salt-tolerant algae, proliferation of invasive species) and alter organic matter processing. The biological degradation caused by freshwater salinization related to potash mining has important management implications, e.g. it could prevent many European rivers and streams from reaching the good ecological status demanded by the Water Framework Directive. Within this context, German publications show several examples of salinity thresholds and biological indices that could be useful to monitor and regulate salinization (i.e. developing legally enforced salinity and ion-specific standards). They also provide potential management techniques (i.e. brine collection and disposal) and some estimates of the economic costs of freshwater salinization. Overall, the German literature on freshwater salinization provides internationally relevant information that has rarely been cited by the English literature. We suggest that the global editorial and scientific community should take action to make important findings published in non-English literature more widely available.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Keywords: biological indicators; freshwater biodiversity; major ions; potash mining; salinity; water management.

Figure 1.

The mine named ‘Güntershall’ situated at Wipper River below the city of Sondershausen (Thuringia, Middle Germany). This mine was one of the many potassium mines that were founded in the early 1900s in this region. Its brines were discharged into the Wipper River, causing a strong salinization here [2,3]. Albrecht [25] reported that an accident had happened at one of these factories around 1930. A surveyor, P. Schiemenz, was instructed to investigate whether this incident had damaged the fauna of Wipper River. In the report about his investigations he wrote that he had found many ‘small green chironomids' in the surroundings of one of these potash mines. This is the first known report about damage of the aquatic fauna by salinization [25]. Although industrial activities in this mining area have been terminated since the 1990s, salinization owing to the introduction of drainage brines from the residue stockpiles still continues [26]. Picture by an unknown photographer, kindly provided by Mr Hans-Jürgen Schmidt. (Online version in colour.)