Featured Research

from universities, journals, and other organizations

Researchers Probe How Microbes Speed Up Acid Production At Mining Sites

Date:
December 15, 2003
Source:
Stanford University
Summary:
Microbes are everywhere, but when they are in mined soils, they react with the mineral pyrite to speed up acidification of mine run-off water. Scientists have been trying to understand the chemistry behind this process that eventually leads to widespread acidification of water bodies and deposition of heavy metals.

Microbes are everywhere, but when they are in mined soils, they react with the mineral pyrite to speed up acidification of mine run-off water. Scientists have been trying to understand the chemistry behind this process that eventually leads to widespread acidification of water bodies and deposition of heavy metals. What a new study has found seems to defy the laws of chemistry: microbes react with the pyrite surface, coating it with chemicals that would be expected to hinder further reactions. Despite the formation of such coatings, however, microbe-mediated reactions occur tens of thousands of times faster than when no microbes are present.

Related Articles


''That's a puzzle,'' said Alfred Spormann, a co-principal investigator on the study. ''This changed surface chemistry should slow down the microbial oxidation but it doesn't.''

The collaborative study was led by co-principal investigators Scott Fendorf, Gordon Brown and Spormann at Stanford. Dartmouth Assistant Professor Benjamin Bostick, Fendorf's former doctoral student who coordinated the research effort, will present the group's findings Thursday, Dec. 11 at this year's San Francisco meeting of the American Geophysical Union (AGU). The AGU is an international scientific society with more than 35,000 members dedicated to advancing the understanding of Earth and its environment.

In mines, oxygen from the air initiates chemical reactions with pyrite, also known as fool's gold. Microbes subsequently react with the pyrite in cyclic processes that result in the rapid production of large amounts of sulfuric acid. The research team wanted to understand how the activity of the microorganisms controls the chemistry on mineral surfaces, and how that chemistry, in turn, controls the activity of the microorganisms. Specifically, they wanted to find out what kinds of iron species and precipitates can be found on microbe-treated pyrite surfaces.

The researchers grew the bacteria Thiobacillus ferrooxidans and Thiobacillus thiooxidans, forcing them to ''eat'' iron or sulfur, the elements that make up pyrite. They examined the products of metabolism using surface-sensitive photoelectron spectroscopy and X-ray absorption spectroscopy. The results give a molecular view of how microbes change the form of the mineral. The bacteria produced surface coatings made up of iron sulfate and the iron oxide goethite. Also, different metabolism products formed when both types of bacteria were studied together compared to when only one type was used. The amount of oxidation produced by the mixed species was not additive compared to oxidation by individual species, however. ''The projects show that there is a fundamental difference between how one organism carries out a process and how a group does so,'' said Bostick.

This study is a continuation of a pioneering molecular-level study by the same team, looking at how heavy metal contaminants partition between a biofilm and a metal surface. The researchers found then that surface type and metal concentration affect the distribution of the metal and the types of products formed.

The researchers will continue to experimentally reproduce and study the complex natural system of microbes and minerals, starting with simple systems and building complexity by sequentially adding more and different microorganisms.

The results may provide insight into other problems, such as tooth decay and metal-pipe corrosion, that arise from the interaction between microbes and the surfaces on which they reside.


Story Source:

The above story is based on materials provided by Stanford University. Note: Materials may be edited for content and length.


Cite This Page:

Stanford University. "Researchers Probe How Microbes Speed Up Acid Production At Mining Sites." ScienceDaily. ScienceDaily, 15 December 2003. <www.sciencedaily.com/releases/2003/12/031212075307.htm>.
Stanford University. (2003, December 15). Researchers Probe How Microbes Speed Up Acid Production At Mining Sites. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2003/12/031212075307.htm
Stanford University. "Researchers Probe How Microbes Speed Up Acid Production At Mining Sites." ScienceDaily. www.sciencedaily.com/releases/2003/12/031212075307.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins