by Josh Palumbo, Forest Management Coordinator
I welcome you to The Nature Foundation at Wintergreen’s attempt to bring some nature and knowledge into your home. The Nine Minute Naturalist borrows from NPR’s lovely 90-Second Naturalist podcast. Since we all have a bit more time on our hands, the goal is to take something that is happening out in our environment and stimulate your brain for roughly nine minutes. Don’t let something as “minor” as a quarantine to keep you from learning. I hope you enjoy!
The Shamokin Springs Nature Preserve (SSNP) is an idyllic high elevation wetland designed to highlight the diverse flora and beautiful babbling streams. Oddly enough, this pristine ecosystem is often the source of numerous complaints of water pollution each year. The cause of these complaints is the orange tinted water in the slow moving stretches of the stream. This edition of the Nine Minute Naturalist will explain the phenomenon of iron-oxidizing bacteria common in springs laden with iron-rich groundwater.
The SSNP is currently experiencing a bloom of iron-oxidizing bacteria in multiple places throughout the braided stream. These blooms occur most often after heavy rains when excessive iron is leaching to the surface. When the water, air and iron meet, bacteria is in heaven. An orange oily sheen appears on the surface and fuzzy slime will grow on the rocks amongst the bacteria bloom. The iron bacteria undergo an oxidation process in order to fulfill its energy requirements. The process changes ferrous iron (Fe2+) into ferric iron (Fe3+) producing the rusty colored slime deposits in the stream water. A byproduct is the oily sheen on the surface. To test if the oily sheen you see in stream water is iron-oxidation or pollution, attempt to disturb the slick. If the oily sheen breaks apart, it is the byproduct of the bacteria bloom. If the sheen flows back into place, it is oil.
The main concern expressed by any passerby of an orange laden bacteria bloom is what is this gross anomaly doing to its environment. While quite unsightly, there is no evidence this bloom poses any threat to the aquatic life in the surrounding area. According to the EPA, this type of bacteria is not listed as a contaminant. This type of reaction has been occurring forever and has not seemed to have any impact on the water quality in the SSNP or anywhere else this reaction is witnessed.
The time is right to be getting out into the woods and watching the leaves change colors before our very eyes. A walk along the SSNP offers wonderful colors in the trees and in the stream. Use this bit of environmental knowledge to impress your hiking partner about the wonderful world of bacteria.