VOLCANISM

Hydrothermal Solutions

Heat

Heat can be transfered to aquifers, increasing the temperature of the water.

Gases

Magma tends to degas as it ascends. These gases can dissolve into the water. When these elements and compounds reach certain concentrations they may be dangerous. Contaminent conditions may subside after the onset of the eruption.

Ash

Suspended Ash

Suspended ash affects the quality of the water supply not only with potable water, but it also inhibits intake features at water treatment facilities. Turbidity can hinder proper disinfecting processes (Jonhston, 1994).

Photo: Michael Dolan

Falling Ash

Falling ash can inhibit the motors and gears of pumping stations, disrupting the distribution of water supplies. It contaminates open water sources (ie. lakes, rivers, streams and reserviors).

Leachates

Leachates from ash particles release cations and anions into the water. High concentrations of Cl, SO4, Na, Ca, K, Mg and F are common with lesser amounts of Mn, Zn, Ba, Se, Br, B, Al, Si, Cd, Pb, As, Cu and Fe. When these elem ents and compounds reach certain concentrations they may be dangerous. The chemical changes often decrease the pH level of the water to harmful levels if consumed by humans or amimals. pH levels have on occasion been measured as low as 5, 7 being neutral, in water supplies. The extent of contaimination is dependent upon the ash to water ratio.

Fluorine (F-) is a more common volcanic contaminent of volcanic ash. In high concentrations it inhibits important enzymes in the body from performing their function. Excess F has been associated with the deaths of livestock.

Debris Flows

Debris flows, particularly lahars, are capable of introducing large quantities of fragmented rock material into water supplies. For more information on debris flows click HERE

Photo: Michael Dolan

Lahars

A lahar can be described as a fast moving slurry of rock fragments and water, triggered by heavy rainfall. They often travel within natural waterways, rivers and streams, which sometimes lead to reservoirs. The thick mud and rock fragments can contaminate water supplies by mixing with the water. Contaminents are introduced by leaching which can add harmful concentratons of some chemicals into the water. Water intake facilities can be damaged by the mud and rock fragments(Johnston, 1994). To find out more about lahars click HERE

Earthquakes

The jolting of the earth by earthquakes can break water supply lines, cutting off water for use. Aquifers can be contaminated if gas, oil or other such pipes are broken. Aquifers can even be redirected due to te movement.To learn more about earthquakes clickHERE

References

Johnston, David M., 1994. Contamination of Potable Water Supplies by Volcanic Ash, Water & Wastes in New Zealand, p 18.

hlshocke@mtu.edu