Are woodchip barriers adding to mercury pollution in our estuaries?

Ecology
Open Access
$2,135
Raised of $6,000 Goal
36%
Ended on 9/13/13
Campaign Ended
  • $2,135
    pledged
  • 36%
    funded
  • Finished
    on 9/13/13

About This Project

We know that woodchip barriers can be used to prevent algal blooms, but we don't know if this method is producing toxic methylmercury at a high rate. Funds for my mesocosms will help us understand the risks and benefits of woodchip barriers as a method of stopping algal blooms.

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What is the context of this research?

Over the past few decades, eutrophication has become a serious issue around the globe. Eutrophication occurs when excess nutrients (usually nitrogen and/or phosphorus) enter coastal waters and stimulate the growth of algae. This leads to problems such as harmful algal blooms, loss of oxygen, fish kills, and drops in biodiversity. A potential solution to this problem is a permeable reactive barrier, or a PRB. This is a fancy term for a bunch of woodchips that have been buried underground so that groundwater must flow through the chips before it goes into coastal waters. The woodchips are made of carbon and provide an energy source for denitrifying bacteria. These microbes are capable of removing the excess nitrogen from the groundwater that flows through the PRB before it reaches coastal waters, thereby reducing the harmful effects of eutrophication. This carbon source is so plentiful that the barrier is also home to other types of bacteria.

In the past, I have measured large fluxes of hydrogen sulfide coming from the barrier. This indicates the presence of sulfate-reducing bacteria. These bacteria also have the ability to methylate mercury that is in the groundwater. Bascially, mercury in its elemental or ionic form can be quite common in some groundwater systems, especially those near urban or industrialized areas. Sulfate reducing bacteria can take this mercury and alter it through their metabolism to methylmercury, which is the toxic form that is found in fish. If ingested, this can lead to brain damage and other serious health effects.

My goal is therefore to determine whether these barriers are solving one problem (eutrophication) only to create another (toxic methylmercury production). To answer this question, I need to build miniature versions of the barrier (called mesocosms) and add some mercury to see whether methylmercury gets produced as a result. I hypothesize that due to a large presence of sulfate-reducing bacteria, there will be more methylmercury coming out of barrier mesocosms as opposed to control ones (barriers that have no woodchips). We will publish these works in quality, peer reviewed journals and keep our backers fully informed of our progress over the course of the research.

What is the significance of this project?

Most areas that are highly eutrophic are also contaminated with mercury, since both are derived from human sources. Before the barrier can be implemented on a larger scale, I need to determine whether they are safe to use in urban areas with high mercury concentrations. I have measured nutrient concentrations at the barrier in the past, and they are very effective at removing nitrate from groundwater. In fact, if you go in the summer to where the barrier is, you can see that the ground above it is bare of algae, while the rest of the beach is covered! However, if it is producing toxic methylmercury at a high rate, it might not be worth these benefits.

What are the goals of the project?

In order to do my mesocosm experiments, I will need money to build miniature versions of the PRBs and get water flowing through them. The tubing and fittings for each mesocosm would cost $600, and I would need around six replicates. This comes to $3,600. The rest will be spent on a pump, sample containers, and analyses. Right now, there is very little mercury in the groundwater at my study site, which is a good thing, but it means that we still do not know how the PRB will function in water full of mercury. Will it create more toxic methylmercury? The mesocosms will allow me to test this hypothesis by adding groundwater spiked with mercury. These funds would go to answering these questions. If I find that the PRB bacterial community appears to be “healthy” and isn’t producing too much methylmercury, this might be an excellent way to help clean up polluted coastal waters.

Budget

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$3,600 will be spent on purchasing chromatography columns and fittings to make the mesocosms. Another $600 will cover the purchase of a multichannel pump to move water through the mesocosms, and another $200 will go to a reservoir to hold water to pump through the mesocosms. The remaining money will be spent on analyses (measuring mercury and nutrients like nitrate to see if the barrier is functioning properly). We can also do one round of sequencing on the sulfate reducing bacterial population to see which bacteria are actually doing the methylation.

Meet the Team

Kenly Hiller
Kenly Hiller

Affiliates

Secondary School-Tabor Academy, GED earned 2007

Undergraduate-Connecticut College, Bachelor of Arts earned 2011

Graduate-University of Massachusetts Boston, Ph.D in Environmental Biology expected 2017
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Team Bio

When I was a kid, I wanted to be a paleontologist and dig up dinosaurs. As I got older, I realized that although that is an awesome job, I really wanted to do something that looked toward the future. In light of global change and the destruction of ecosystems due to human interference, I wanted to work on applied environmental science to try to reverse some of the damage.

I started off by attending the Semester in Environmental Science at the Marine Biological Lab in Woods Hole, MA, during my junior year of undergraduate studies. It was there that I started my work on the barriers. Back then, I studied the geochemistry of the barriers (how much nitrate they removed and what other substances were being created inside it), and whether they affected the abundance of animals that lived nearby. I continued this research for my senior honors thesis during the next summer and during my senior year at Connecticut.

My advisor at Connecticut College got me interested in the microbial side of things, since they are the ones that power biogeochemistry (the cycling of elements by living things) in the barriers. Bacteria are the ones that actually do the nitrate removal, after all. I worked with her on her research that looked into ammonia-oxidizing archaea living in Sippiwissett Marsh, not far from Woods Hole. These microbes had recently been discovered to play a role in nitrogen cycling in salt marshes.

Following this path naturally led me to come work in Dr. Jennifer Bowen's laboratory at UMass. She specializes in bacteria and the nitrogen cycle. In my first year of graduate study, I became interested in not only the bacteria in the barrier involved in nitrogen cycling, but also those involved in other processes as well. My interest in methylmercury in groundwater and how bacteria can affect how much is produced was born.

In addition to bacteria, I also enjoy ice hockey, sailing, and British television : )

Kenly Hiller

When I was a kid, I wanted to be a paleontologist and dig up dinosaurs. As I got older, I realized that although that is an awesome job, I really wanted to do something that looked toward the future. In light of global change and the destruction of ecosystems due to human interference, I wanted to work on applied environmental science to try to reverse some of the damage.

I started off by attending the Semester in Environmental Science at the Marine Biological Lab in Woods Hole, MA, during my junior year of undergraduate studies. It was there that I started my work on the barriers. Back then, I studied the geochemistry of the barriers (how much nitrate they removed and what other substances were being created inside it), and whether they affected the abundance of animals that lived nearby. I continued this research for my senior honors thesis during the next summer and during my senior year at Connecticut.

My advisor at Connecticut College got me interested in the microbial side of things, since they are the ones that power biogeochemistry (the cycling of elements by living things) in the barriers. Bacteria are the ones that actually do the nitrate removal, after all. I worked with her on her research that looked into ammonia-oxidizing archaea living in Sippiwissett Marsh, not far from Woods Hole. These microbes had recently been discovered to play a role in nitrogen cycling in salt marshes.

Following this path naturally led me to come work in Dr. Jennifer Bowen's laboratory at UMass. She specializes in bacteria and the nitrogen cycle. In my first year of graduate study, I became interested in not only the bacteria in the barrier involved in nitrogen cycling, but also those involved in other processes as well. My interest in methylmercury in groundwater and how bacteria can affect how much is produced was born.

In addition to bacteria, I also enjoy ice hockey, sailing, and British television : )

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Project Backers

  • 18Backers
  • 36%Funded
  • $2,135Total Donations
  • $118.61Average Donation
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