As much as a quarter of the world's population is supplied by water derived from karstic aquifers.

Karst regions are host to many mineral deposits (including significant lead, zinc and placer tin deposits, and form important hydrocarbon reservoirs.

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Most dissolution occurs when rainwater picks up carbon dioxide from the air, and decaying organic matter in the soil, becoming more acidic and then percolates through cracks dissolving the rock.

Karst in carbonate rocks is formed by their dissolution by acidic water.

Though most abundant in humid regions, karst can also be found in arid terrains, either as relict karst formed during former wetter periods, or where H2S in groundwater rising from reducing zones at depth oxidizes to produce sulphuric acid.

Such processes can produce large caves, such as the Carlsbad Caverns of New Mexico.

Diagnostic features such as sinkholes (dolines), sinking streams, caves and large springs are the result of the dissolutional action of circulating groundwater, which may exit to entrenched effluent streams.

The varied interactions among chemical, physical and biological processes have a broad range of geological effects including dissolution, precipitation, sedimentation and ground subsidence.

Instability of karst surfaces leads annually to millions of dollars of damage to roads, buildings and other structures in North America alone [see surface subsidence].

Radon levels in karst groundwater tend to be high in some regions, and underground dissolution conduits can distribute radon unevenly throughout a particular area.

Karst hazards include sinkhole flooding, sudden cover collapse, leakage around dams, collapse of lagoons resulting in waste spills, irregular rockhead and radon infiltration into homes.