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.

''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 April 23, 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 April 23, 2014).

Share This



More Plants & Animals News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Leopard Bites Man in India

Raw: Leopard Bites Man in India

AP (Apr. 22, 2014) A leopard caused panic in the city of Chandrapur on Monday when it sprung from the roof of a house and charged at rescue workers. (April 22) Video provided by AP
Powered by NewsLook.com
Iowa College Finds Beauty in Bulldogs

Iowa College Finds Beauty in Bulldogs

AP (Apr. 22, 2014) Drake University hosts 35th annual Beautiful Bulldog Contest. (April 21) Video provided by AP
Powered by NewsLook.com
805-Pound Shark Caught Off The Coast Of Florida

805-Pound Shark Caught Off The Coast Of Florida

Newsy (Apr. 22, 2014) One Florida fisherman caught a 805-pound shark off the coast of Florida earlier this month. Video provided by Newsy
Powered by NewsLook.com
Breakfast Foods Are Getting Pricier

Breakfast Foods Are Getting Pricier

AP (Apr. 21, 2014) Breakfast is now being served with a side of sticker shock. The cost of morning staples like bacon, coffee and orange juice is on the rise because of global supply problems. (April 21) Video provided by AP
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:
from the past week

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