A large number of lakes and rivers in the Northern hemisphere are suffering from the effects of acid rain. Additionally, if the ground is of poor quality (consisting of limestone or rocks which are not easily liable to deterioration), this acidification of the water may lead to the disappearance of all aquatic, animal and plant life.

Based on an invention patented by Solvay, the sodium ions may be locked into the sediment in a lake using sodium carbonate added to the lake and acting as a ionic exchanger. Several Swedish lakes have been treated very successfully and this process is now under development