Acidification of Freshwater Resources

Abstract

All freshwater resources, groundwaters, lakes, and rivers, can be acidified. Inland waters receive acid inputs via the atmospheric path and by direct inflows from surface runoff and from groundwaters. Sources of acids are smoke from burning of fossil combustibles and from volcanoes, acidic wastewater from industrial plants, geogenic acids from weathering of sulfidic deposits at their natural sites, or from oxidation of sulfides with/after mining ores, hard coal, and lignite. Accordingly, the acid inputs into ground‐ and surface waters are either distributed by acid rain over long ranges and large areas, or they are restricted to local impacts by draining of mines, dumps, or sulfidic natural deposits. Both pathways are found in active volcanoes regionally releasing volatile acids into the atmosphere and being direct, local sources of highly mineralized acidic brines. Last but not least, freshwaters can be directly acidified by inflows of industrial wastewater. The effect of acidic inputs is larger in soft water because of the low content of ions and low buffering capacity.

Microbial Alkalinity Production to Prevent Reacidification of Neutralized Mining Lakes

“…The mining lakes can be divided into two types based on the lignite extraction process: small shallow littoral lakes with a mean depth of less than 5 m and very large lakes with a mean depth of more than 20 m (Nixdorf and Kapfer 1998). Almost two-thirds of these mining lakes have a pH of 2.0 to 3.5 and high concentrations of acidity, iron, and sulfate (Geller 2005;Klapper and Schultze 1995). There is intense public interest in neutralizing these lakes, converting the former mining area to a recreation and tourist zone, and protecting the ground water resources.…”