Ferskvand

Ferskvand is the Danish term for freshwater, the water that contains low concentrations of dissolved salts. Freshwater is typically defined by a salinity of under about 0.5 parts per thousand, in contrast to seawater which is around 35 ppt. It includes rivers, lakes, groundwater, and most wetlands, and it is essential for drinking water, irrigation, and the health of most terrestrial ecosystems.

Most of the Earth's freshwater is not readily accessible. A large portion is stored in glaciers and ice caps, and a substantial part exists as groundwater deep underground. Only a relatively small share is present as rivers, lakes, and other bodies from which humans can extract water for everyday use without extensive treatment.

Freshwater is replenished primarily through precipitation and snowmelt and moves through the landscape in the hydrological cycle. It circulates between the atmosphere, land, and underground, and is lost again by evaporation and plant transpiration. Local availability depends on climate, geology, and land cover, which together influence recharge rates and storage.

Human use of ferskvand typically requires treatment to meet drinking-water standards. It supports agriculture, industry, and domestic needs, but freshwater resources can be stressed by over-use, pollution, and climate-change impacts such as altered rainfall patterns and reduced snowmelt. Common quality issues include nutrient pollution causing eutrophication, chemical contaminants, salinization from irrigation, and saltwater intrusion in coastal aquifers.

Management of freshwater resources involves protecting watersheds, reducing pollution, improving water-use efficiency, and expanding supply through recycling and, where appropriate, desalination. Climate change poses ongoing risks by shifting precipitation, diminishing glaciers, and increasing the frequency and severity of droughts, highlighting the importance of sustainable freshwater governance.