Fresh water is the freely available (i.e. without the water bound in minerals and living beings) in which no or only very small amounts of salts ( salinity of less than 0.1 percent) are dissolved, regardless of its physical state . The proportion of fresh water in the earth's water balance is very low, at 2.6 to 3.5%, depending on the estimate; A significant proportion of the global freshwater resources is bound in ice in the form of glaciers and the ice of the polar caps or is available as fossil groundwater . The salt water of the oceans dominates.
By UNESCO in 2003 as " Year of Freshwater proclaimed".
The vast majority of global freshwater resources are bound in the ice of the glaciers in both polar regions and in some high mountains . In addition, fresh water is found, in particular, in the form of surface water from streams , rivers and lakes as well as in groundwater and aquifers formed in particular by seepage water from water-permeable rock .
So far, submarine springs in which seeped fresh water reappears in the salt water of the seas cannot be used.
Fresh water is the habitat of many living things, its ecology is examined by limnology .
The rise in the CO 2 concentration in the Earth's atmosphere in the Anthropocene leads not only to acidification of the world's oceans but also to acidification of freshwater lakes.
Due to the global warming , the greenhouse gas emissions of the northern freshwater lakes could rise times 2.7 to 1.5 to as the vegetation cover in forests of northern latitudes and increases thereby dadeshalb more organic molecules get into the water, which microbes in the lake sediments be dismantled. During this degradation process, carbon dioxide and methane are released as by-products.
- Helmut Lehn, Oliver Parodi: Water - elementary and strategic resource of the 21st century. I. An inventory. Environmental sciences and pollutant research 21 (3), pp. 272–281 (2009), ISSN 0934-3504
- ↑ deutschlandfunk.de , Forschungs aktuell , April 25, 2017, Lucian Haas: New dirt in old water - fossil groundwater contains impurities ( ondemand-mp3.dradio.de ( Memento of the original from April 27, 2017 in the Internet Archive ) Info: Der Archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this note. , April 26, 2017)
- ↑ CO2 in air and water - acidification also affects freshwater animals . In: Deutschlandfunk . ( deutschlandfunk.de [accessed on February 4, 2018]).
- ↑ Andrew J. Tanentzap, Amelia Fitch et al. a .: Chemical and microbial diversity covary in fresh water to influence ecosystem functioning. In: Proceedings of the National Academy of Sciences. , S. 201904896, doi : 10.1073 / pnas.1904896116 .
- ↑ Climate change could double greenhouse gas emissions from freshwater ecosystems. In: cam.ac.uk . November 18, 2019, accessed November 21, 2019 .
- ↑ Climate change could double greenhouse gas emissions from freshwater ecosystems. In: solarify.eu. November 20, 2019, accessed November 21, 2019 .