Is it Oil, or Is It Iron?

The Pennsylvania Department of  Environmental Protection would like to remind you all that not all scum is pollution. Oil Sheens - All That Glitters ... Isn't Necessarily Pollution

One of the most visible and obvious signs of water pollution is an oil sheen. Seeing a shiny, translucent reflection on a pond or lake just looks wrong - but did you know that not all sheens are the result of pollution? Here is what you should know about sheens, how to tell the difference between naturally occurring sheens and those that are the result of pollution, and what you should do if you discover a sheen caused by pollution.

A sheen is "an iridescent appearance on the surface of the water." The iridescent, lustrous appearance could be caused by a petroleum spill finding its way into the water - or the sheen could be a naturally occurring result of iron bacteria. Iron bacteria are small living organisms which naturally occur in soil, shallow groundwater, and surface waters and are harmless to the environment. Petroleum sheens on the other hand are harmful to the environment and should be reported to the Pennsylvania Department of Environmental Protection (DEP). But how can you tell the difference between the two and what should you do if you discover a sheen caused by pollution?

A very simple, yet very effective method to tell if an oil sheen is organic or the result of pollution, is to throw a rock into the sheen, or to break it apart with a stick. A bacterial sheen will typically break into small platelets when disturbed while a petroleum sheen will quickly reform. Another way to tell them apart is by smell. Natural sheens don't smell like petroleum.
. . .
Please remember, the next time that you see an oily sheen on surface water, do the rock test to determine if the sheen is organic or the result of pollution and report all pollution sheens to DEP. 

I take from this that Pennsylvania has a substantial number of false reports of oil pollution caused by iron bacteria. The effect can be exacerbated by mines, like, say coal mines that Pennsylvania has in abundance, that can bleed acid mine waste loaded with the reduced iron that iron bacteria grow on, and cause the film, thus being a sign of pollution, albeit a different type of pollution than oil.

Several different pieces of ironstone on the beach today

However, the process is, in fact natural in many places, and if it goes on long enough can produce a well known form of iron ore, bog iron, which Vikings exploited as iron ore.

The process is quite common around here, usually in drainage ditches. Moreover, we have lots of evidence for the process from the past, in the form of ironstone, a form of sandstone commonly found in the ground, and washed up on our beaches.

Taiwanese Scientists Cast Doubt on "Iron Hypothesis"

John H. Martin

“Give me a half tanker of iron,
and I will give you an ice age.”

Said John H. Martin, one of the great oceanographers of my age. His hypothesis was that in areas of the ocean with "high" nutrient concentrations and low chlorophyll (HNLC areas), like much of the Pacific, iron was the limiting nutrient, and that adding iron could stimulate oceanic primary. In another link, stimulating primary production would increase the rate of sedimentation of the fixed carbon produced by the phytoplankton, and remove some carbon dioxide from the atmosphere, offsetting or even reducing atmospheric CO2 and offset or even reverse global warming. He didn't really propose to set off a new ice age.

A lot of experiments were carried out to test "the iron hypothesis." It worked sometimes, and it didn't work sometimes. Biology is like that. It's not as straightforward as rocket science. New studies by Taiwanese researchers also find that iron fertilization was not always effective:

Taiwanese Researchers Dismiss Iron Fertilisation Carbon Capture

Taiwanese researchers have poured cold water on the possibility of capturing carbon with artificial algae blooms, created by fertilising the oceans with iron. The problem appears to be that the artificial algae bloom depletes other essential ocean nutrients, causing a reduction in algae growth elsewhere in the ocean.

To alleviate the impact of global warming, scientists have proposed a hypothesis of “iron fertilization,” assuming that adding iron into the ocean can boost the growth of algae to absorb the carbon dioxide in the air.

However, researchers in Taiwan have found flaws in this hypothesis.

Working with Columbia University, a NTU research group led by Haojia Abby Ren, associate professor of Geosciences at National Taiwan University (NTU), has poured iron into 12 waters around the globe to perform experiments on the “iron fertilization” hypothesis. It turned out algae only thrives in one-third of the areas tested.
The growth of algae requires nutrients other than iron, such as nitrate and phosphate. With the growing amount of algae, consumption of these nutrients also increases in the area. But when currents carry the algae to other waters, the nutrients become relatively scare elements, making algae hard to grow.

Read more: http://international.thenewslens.com/post/312664/

This claim is backed by an earlier study, which suggests that increased iron outflows into the ocean during the last ice age, caused by glaciers scraping iron rich minerals into the sea, did not increase algae growth in equatorial regions, because increased algae growth in subantarctic zones depleted other ocean nutrients.

One third of the ocean is a lot of ocean . . .