Nuetralizing an acid lake.

.Image from http://www.irishlime.com

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Formation of Volcanic Lake

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Click here to whatch a movie of an acid waterfall and a fumarole in Poas Volcano, Costa Rica

Volcanic and Acid Rain Induced Acid Lakes

Introduction

There are two main divisions to acid lakes, those that are created by acid rain and those that are created in creators of active volcanoes. This web page will attempt to explain the process behind these lakes and their similarities. I hope that through this website I will be able to clarify some of the misconceptions that have arisen about acid lakes thanks to the inaccuracies of some Hollywood movies and shows.

Facts about pH and Lakes:
*pH ranges from 0-14, anything below 7 is an acid and above a 7 is a basic. pH that is around 7 is considered a neutral
*Acid rain is produced by emissions of N and S (Marine Biological Laboratory)
*The pH for most lakes and streams tends to be between 6-8 (EPA).
*Lakes can be naturally acidic (EPA)
*The turnover rate in a lake will affect the acidity of the water (Marine Biology Laboratory)
*The pH can be affected by the geology of the area (such as by having limestone in the watershed) (Marine Biology Laboratory)
*One of the lowest pHs in a lake is in Little Echo pond located in New York, which has a pH level of 4.2 (EPA)
*In the province of Quebec in 1980, the were 29,000 lakes with waters acidic enough to affect the living organisms (Pratte)

Acid Lakes and Acid Rain

Acid rain is the result of pollutants in the air bonding with precipitation, caused by the different sources such as factories and cars. Acid rain is an acidic disposition, which is divided into two different categories: wet and dry. Acid rain comes in the form of rain, fog, sleet or snow and thus is a wet disposition. The effects of acid rain on lakes have been studied and it has been found that different factors contribute to the acidity of the lakes. The acidity as we shall soon see, is not entirely dependant on the acidity of the rain although they are correlated.

Buffering

One of the main element that determines the acidity of a lake is the buffering capacity. Buffering is the term used to describe if the soil can get rid of the acid neutrons. To do this, the soil has to neutralize the acid compounds (EPA). Therefore, if the lake has good buffering you can expect a higher pH levels, versus the areas that have a lower buffering capacity although they may both receive the same amount of acid rain.

Stability of H20 amounts

Other factors that may affect the pH of a lake are also based on the amount of water entering and leaving the lake. If the amount of water that is in the lake does not change with a certain amount of frequency, the acidity with not be flushed out (Marine Biology Laboratory). The “vulnerability” that a lake has to acid rain also depends on the “depth of the soil and the path that the water follows as it drains through a watershed” (Peterson, 332). If the acids in the water do not have time to process themselves through the sands, they will not be able to go through the amount of weathering that they need, and thus, the water will go into the lake with a low pH, affecting the lake.

Scientist studying sediments at bottom of a lake

Image from http://www.mbl.edu/publications/LABNOTES/1.1/acid.html

The kind of vegetation may also have an effect on the pH of the water going to the lakes form the watershed. It was observed by Nicholas L. Clesceri of Polytechnic Institute, that Coniferous trees may increase acidity of water while Deciduous trees seem to lower the acidity (Peterson 333).

Impacts:

· There is a largel number of different living organisms which must have a strict pH level in the water to survive. Tampering with the pH of water may kill the different organism in the water.

PH levels needed for certain organisms to survive.

Image from http://www.epa.gov/airmarkets/acidrain/effects/surfacewater.html

· Lose of natural resource which in turn impacts the economy

· Lose of the places for humane enjoyment (the nitrogen in the water may cause algae to grow to such dimensions that we would be swimming in green slime for example) (EPA).

Volcanic Lakes

Image from http://lawr.ucdavis.edu/faculty/gpast/lakes.html

Volcanic lakes are formed in the area where water can collected near gases from a volcano; this may mean that the lake can be inside the actual creator of the volcano! It is estimated that 12% of the worlds Holocene volcanoes have a lake, although not all of them have to be acidic (McDonough).

The gases that are responsible for the low acidity of the water (which can go down to a pH of one) are caused by fumaroles. The fumaroles are notorious for sending off gases such as CO2 and SO2 (Rowland). A fumaroles can also emit gases and steam at temperatures of 100 to 1,000 Celsius (Sutherland). It was recorded that in 1919, that 1.3 million tons of HCI, 0.2 tons of HF and 0.3 million tons of H2S were released by fumaroles (McBirney, 322)! It is not a wonder that with these kinds of geologic creations fueling these lake’s acidity, they would form such marvelous and unique lakes.

There must be a balance when it comes to heat, there must be a non-pore like substances to sustain the water, and there must be rain fall so that these lakes may sustain themselves otherwise they will dry up (McDough).

The lakes are set into five distinct categories, which are determined by the activity at the bottom of the lake. They are:

Peak Activity Volcanic Lakes: these lakes are unable to keep the balance needed to have a lake and thus, they disappear. (ex. Poas Volcano)

Poas Volcano.

Image from http://www.rocinantestravels.com

High Activity Volcanic Lakes: The acid content is high as well as the salt content yet they have equilibrium and do not disappear (ex. El Chichon, Mexico).

El Chichon

Image from www.geo.mtu.edu/~raman/ Elchichon.html

Medium Activity Volcanic Lakes: pH between one and three (ex. Keli Mutu)!

Keli Mutu

Image from http://www.sea-world-club.com/Kelimutu.jpg

Low-Activity Volcanic Lakes: Usually have more water content the rest of the lakes. Have large amounts of Carbon dioxide (ex. Lake Nyos, Cameroon).

Lake Nyos

Image from http://www.mala.bc.ca/~earles/nyos-view.jpg

No-Activity-Volcanic Lakes: there is hydrothermal spring water present, yet there is no barely any volcanic activity there (ex. Creator Lake). (McDonough)

Creator Lake

Image from http://www.mindspring.com/~dsheppard/photos/chile/020401i.jpg

Poas, in Costa Rica is one of the largest acid lakes, which basin was formed after an eruption in 1953 (Scripps). It’s acidity ranges around one, and it’s temperature is about 85 Celsius. In 1989 the stability of the lake (remember that it is a Peak Activity Volcanic Lake!) was not good enough, thus it resulted in the water draining away. The liquid sulfur in the water was left behind and was two meters deep! It was the first time that liquid sulfur was seen on the Earth (Rowland)!

Impacts:

· Tourism: Because of the uniqueness and beauty of these lakes, many want to see them!
· We cannot forget that these lakes are volcanic. Therefore, the areas around these lakes are susceptible to the same kinds of dangers that come along with having an active volcano around (McDonough).
· The lakes themselves may have carbon dioxide, which if it emerges, may kill the people around the area (such as from Low-Activity Volcanic Lakes). Such an example was lake Nyos in Camaroon (McDonough)
· The water of the lakes may go into the local watersheds (there still needs to be more research done on this topic) (Paternack and Varekamp)

Literature Cited

Marine Biological Laboratory "Acid Rain and the Fate of a Lake." vol. 1 Number 1. 1998. 04/17/04. <http://www.mbl.edu/publications/LABNOTES/1.1/acid.html>

McBirney, William Volcanology. San Francisco: Freeman, 1979

McDonough, Tom. "Other Crater Lakes." Volume XXXI. 2000. 04/14/04 <http://www.nps.gov/crla/notes/vol31.htm>

Peterson, Ivars. Acid Lakes and Thin Soils. "Science News" Vo. 123 Issue 21, pages 332- 333. 04/14/04 EBSCO Host

Pasternack, Greg. "The Science of Volcanic Lakes." 1996. 04/10/04 <http://lawr.ucdavis.edu/faculty/gpast/lakes.html

Paternack, G.B, Varekamp, J.C. Volcanic Lake Systematics I. Physical Constraints. 1997. (<http://lawr.ucdavis.edu/faculty/gpast/lakes.html>) To access the page with the link to this .PDF format paper click here!

Poas, Costa Rica. <http://volcano.und.nodak.edu/vwdocs/volc_images/north_america/costa_rica/news_poas.htm>

Pratte, Andre. "Global Warming Slows Down the Elimination of Acid From our Lakes." The Connected Classroom (La Press). 04/16/04

Rowland, Scott. "What causes an acid lake? Do they take a long time to form or can a regular lake become one?" University of Hawaii. 04/17/04. <http://volcano.und.edu/vwdocs/frequent_questions/grp4/question235.html>

Scripps Instituition of Oceonagraphy. "Volcano Expedition from the field in Costa Rica." 04/17/04. <http://www.sio.ucsd.edu/volcano>

Sitherland, Lin The Volcanic Earth.Sydney: UNSW, 1995

United States Enironmental Protection Agency. "Effects of Acid Rain: Lakes and Streams." 04/17/04 <http://www.epa.gov.aimarkets/acidrain/effects/surfacewater.html>

Author: Melissa Segovia
Creation/revision date: April 19, 2004

Link to other Student Webpages for 2004 Earlham Physical Geology

Copyright © 2004 Earlham College. Revised April 18, 2004 . Send corrections or comments to parkero@earlham.edu