What’s Going on in our Aquifers?

By: Jessica Robertson

Most of us rely daily on ground water stored in aquifers, whether it provides our drinking water or our morning shower or whether it irrigates the crops that we consume. We don’t often think about the goings on that occur deep underground before we see any of that water, but the aquifers are an important habitat for complex microbial life. This interesting ecosystem may hold a promising answer for removing harmful carbon dioxide from our atmosphere.

Deep underwater in the aquifers, oxygen content is very low, if present at all. Microbes must rely on other substances, namely minerals like iron and sulfur, to produce energy. The byproducts of the microbes’ “breathing” these solid minerals are reactive ions that will readily interact with other chemical compounds present in the aquifer. These reactions can dramatically shape the environmental state of the nearby water, soil, or rock, and, importantly, the crops watered by groundwater.

When samples of some deep aquifer microbes were studied, it was determined that even though iron is a better source of energy, many organisms were using iron and sulfur, an unusual combination. With the pH of many aquifers being more alkaline than surface waters, reconsideration of microbial energy calculations showed that sulfur is more important to deep aquifer dwelling microbes than previously known. With interactions occurring between different species of microbes and their dependence on each others’ reactions, even without measureable levels of a given byproduct, the amount of energy cycling through the aquifer could be very high.

What this new understanding means is significant. Carbon sequestration has become difficult in light of new findings suggesting that soil is a less efficient carbon capturer than previously assumed. With the high levels of reactive ions residing in the deep aquifers thanks to the symbiotic relationships between mineral-fueled microbes, it may be possible to inject harmful carbon dioxide from the atmosphere into the aquifers; it will react with ions there, forming stable and solid compounds and sinking to the bottom of the aquifers, never to seep to the surface again.

Finding this new information regarding these deep-water microbes has been an illuminating piece of the puzzle that is carbon sequestration. Now knowing more details of the dependent relationship of iron- and sulfur- reducing microbes, it may be possible to clean up our atmosphere. 

New Prospect for Clean Up of Contaminated Soil

By: Jessica Robertson

It is no secret that the high level of pollution of our planet, from sources like car engines or even cigarettes, is harmful. One particularly common contaminant, polycyclic aromatic hydrocarbons (PAHs), is a toxic tar substance that is believed to be a cause of cancer. These contaminants, and others, are often trapped in soil; PAHs, particularly, were thought to be mostly immobile in soil, binding to soil particles and being unable to dissolve in water. These qualities made clean up of contaminated soil quite a challenge.

A new study shows, however, a way to deal with these pesky contaminants. Some tiny microorganisms that do have the ability to move, like the unicellular slipper-shaped ciliate Tetrahymena pyriformis, have the surprising ability to take up the substance into the lipid layer of their cell membrane and act as a shuttle to the PAHs. This method means a much faster transport of the PAHs than the method of simple diffusion; furthermore, the ciliates are still able to transport the PAHs when there is no fluid flow, a situation where diffusion would be impossible.

Increasing the mobility of the PAHs by ciliate transport can increase the exposure of the PAHs to bacteria that can degrade them or to plant roots that can absorb them. These being the two main methods of biological treatment of PAH-contaminated soil, introducing such micro-organisms to contaminated soil can speed up what used to be a lengthy bioremediation process. 

BPA Holds True Danger

By: Jessica Robertson

It’s in manufactured products everywhere, from the lining of metal food containers to dental composites, but suspicion continues to grow about the safety of biphenyl a, better known as BPA. Canada has already deemed it a toxic chemical, but the United States is taking its sweet time to address the dangerous compound. Some researchers attribute the dangerous characteristics of BPA to its chemical similarity to biological hormones, especially estrogen, androgen, and thyroid hormones. Since studies on rodents have already shown BPA to be linked to abnormalities like cancer and immune, reproductive, and brain function problems, the United States has extended the studies to include primates. In previous studies, BPA was shown to alter fetal development when rodent mothers were exposed daily to very low doses of BPA, which is cause for alarm and for further research.

Funded by the National Institutes of Health, a recent study on rhesus monkeys was considered to be a very similar model to what likely happens within the human system when a pregnant mother is exposed to BPA. Though the rhesus monkeys in the study were exposed to a level considered to be far less than the levels humans are daily exposed to, tissue samples showed damage to the mammary glands, the ovaries, the brain, the uterus, the lungs, and the heart in rhesus monkey fetuses whose mothers were exposed to BPA. It is likely that, often, actual human exposure to BPA is underestimated in both measured levels and in estimated danger. Not only does the study provide evidence that BPA does pass from mother to fetus, but it also provides evidence that BPA causes serious dangers for developing fetuses.

Hopefully the dramatic findings of this study encourage stronger regulations against such a ubiquitous but harmful chemical.