Avainsana-arkisto: research

The first Finnish field trial of on-site sediment cleanup with activated carbon

Part 1: the method and preceding lab work

What you might think of when hearing about sediment clean-up (remediation) is the conventional method of dredging the contaminated material and depositing it somewhere else (off-site methods). But did you ever try grabbing a fistful of mud from under your feet when you’re standing in the water? Not so easy! You usually manage to get some to the surface, but what about all that slurry that stays suspended in the water? In sediment remediation, this can easily cause even more trouble, since it leads to increased dispersal of contaminated material over the water body, as well as increased exposure to everything that has to swim through the water-sediment suspension. Besides that, an excavator vessel is not the cheapest thing to rent either.

Activated carbon -based “on-site” remediation has been proposed as an alternative method. The basic idea is to add the activated carbon as a sorbent straight to a contaminated site, where it binds the contaminant so strongly, that it becomes unavailable for organisms to assimilate and accumulate. So while the pollutant is still in the sediment, it is rendered mostly harmless. It works pretty much the same way as medical activated carbon: The poison that you accidentally ate is bound and thus prevented from entering your bloodstream, from where it could cause havoc. The only difference in sediment remediation is that this sequestration of contaminants happens already before they are taken up by an organism. A more detailed description of the method and its mode of action you can find here.

Testing activated carbon for sediment remediation in the lab.
Testing activated carbon for sediment remediation in the lab.

In our current research we are focusing on the use of activated carbon to clean up sediments polluted with PCBs.  This group of chemicals that is found in the environment of most parts of the world. Listing all the uses and potential dangers of these PCBs in the environment would probably fill another blog post. In brief: it was seen as harmful enough for a worldwide (!) ban of production and use in 2001. One of the biggest problems with PCBs in the environment is their persistency and the fact that they accumulate easily in organisms that are exposed to it.

This is where activated carbon enters the stage: many researchers, including our own group, found that already small doses of activated carbon suffice to prevent almost any of this accumulation of PCBs. So you might say: “Great! It sounds like a great alternative to the messy and laborious dredging operations”. But as Bernard Shaw once said “Science never solved a problem without creating ten more” – we also found that activated carbon itself might have negative side effects to certain organisms. Our job is now to find out if the new problems we create are actually worse than the original one, or if they are a minor trade-off. Our lab studies showed a relatively “balanced” situation, showing both high remediation efficiency accompanied by strong adverse effects. However, lab studies are always limited in their meaningfulness, because we are bound to exclude a lot of parameters that make up a natural environment.

Working with activated carbon powder in the lab can be pretty messy.
Working with activated carbon powder in the lab can be pretty messy.

Therefore the next logical step was to bring the tests of activated carbon based sediment remediation to the field. So in August 2015 our research group has set up the first ever field trial in Finland aimed at investigating the potential and the risks of this method. How this looked like and worked in detail, you can find out in the second part of this blog post.

Text by Sebastian Abel, photos by Sebastian Abel, Jarkko Akkanen and Inna Nybom

Nice handwork and beautiful lab ware – building up the experiment and the first sampling

In my previous post, I told about preparations before an experiment can be started. Some more preparations  were still needed while the worms were creating new heads. Exposure sediments should be prepared – spiked, as we call it. Necessary amount of fullerenes to be added to the sediment was calculated after determining concentration of the fullerene suspension; concentration measurements are pretty beautiful, because of the purple color of fullerenes in the measuring solution.  Spiking is done by “a home-made spiking machine”, which means a metal blade stirred by a drill: it provides forceful mixing of chemical to sediment. Also, artificial freshwater for exposure jars was prepared.

Spiking the sediment with fullerene nanoparticles.
Preparing everything for the experiment. In the middle, spiking the sediment with fullerene nanoparticles.

Everything was finally ready for building up the experiment: spiked sediment, size-synchronized worms and artificial freshwater. The next step was building up the exposure jars with an aeration system. At first, the sediment was placed on the bottom and then artificial freshwater was carefully poured above the sediment. No matter how you pour the water, you always have a blended mix which has to let settle for one or two days before aeration can be started and the worms added. The next step is to let the exposure go on and maintain pH and oxygen content at suitable level for the worms.

Microcosmos with Lumbriculus variegatus, the tubes are for aeriation.
Microcosmos with Lumbriculus variegatus, the tubes are for aeriation. On the right, the worms are in their typical feeding position.

After 7 days it was time to collect the first worm samples, which means whole-day handwork. And how to carry that out? The exposure sediment was poured to a sieve and then carefully seek and pick up every worm using a dentist tool.

In the end, you must find your worms. Sieving is a handy method for that.
In the end, you must find your worms. Sieving is a handy method for that.

The worms are put to clean water to empty their guts before they are ready to be weighed in hand-made –how else 😉 – tiny foil cups. After recording wet weights, the worms are either dried or transferred to a freezer waiting for fullerene analysis.

Our laboratorian trainee Risto Pöhö weighing the worms at the end of the experiment. Note the handy tool for making weighing cups.
Our laboratorian trainee Risto Pöhö weighing the worms at the end of the experiment. Note the handy tool for making weighing cups.

Text by Kukka Pakarinen

Pictures by Kaisa Figueiredo, Risto Pöhö, and Kukka Pakarinen

New opportunities for research co-operation at IIES workshop

The University of Eastern Finland is one of the 17 international university partners taking part in the International Institute of Environmental Sciences (IIES), initiated in 2015 at Trent University, Canada, where the 1st Annual IIES Scientific Workshop was held. The vision of the institute is to become a global leader in the development of research and policy for the management of environmental issues having international dimensions, and it brings together world class research scientists and policy analysts from institutions from around the globe to work collaboratively, sharing expertise, facilities and research programs. The 2nd annual scientific workshop of IIES was held at the University of Eastern Finland, in Kuopio, August 21-24. Altogether 74 scientists from seven different countries took part on this workshop, each one presenting scientific work, new methods or ideas to the international audience of environmental scientists.

Participants of 2nd IIES workshop in Kuopio.
Participants of the 2nd IIES workshop in Kuopio.

Our research group of aquatic ecotoxicology attended the workshop with four top-quality researchers and three oral presentations about relevant ongoing research questions and projects: effects of metal mining on fresh water ecosystems, bioaccumulation of PCBs in fresh water mussels and fish, and sediment amendments and remediation of aquatic systems. The actual workshop days consisted of oral presentations in an auditorium, and poster presentations during the coffee and lunch breaks. Altogether 32 oral presentations were heard, added with 14 poster presentations at the poster corner.

Dr. Jarkko Akkanen presenting the use of sediment amendments in remediation of aquatic systems.
Dr. Jarkko Akkanen presenting the use of sediment amendments in remediation of aquatic systems.

Scientific meetings, conferences and workshops are not only about pure research, but also include lots of networking, different cultural and social activities where students meet senior scientists, European meets Asian and American, and academia meets policy makers. The days in scientific meetings can sometimes be very long, no matter how interesting they are. Social activities and get-togethers make an important part of every scientific meeting, and this workshop was not an exception to this. Before the first actual workshop day, the participants of the workshop got together in a dinner hall of the hotel to get to know each other and share ideas and experiences. Some had been in Finland several times before, but many were here for the first time in their life. Some had travelled for a whole day and night from a distant country, while the others came from a city nearby taking just a-2-hour-long bus ride to arrive. On the second evening of the workshop the city of Kuopio arranged a reception at the city hall for the workshop audience – good food, quality wine and good company, what else can you except from a night like this? The third day’s evening culminated in a 3-course dinner at the Puijo Tower Restaurant, where we could see the beautiful sunset over the Finnish lake scenery and the city of Kuopio at the other side. We also got to visit the Puijo Tower FMI/UEF/ICOS measurement station at the top floor of the tower.

It is easy to smile, when your presentation is over! Kaisa Figueiredo in Puijo Tower
It is easy to smile, when your presentation is over! Kaisa Figueiredo in Puijo Tower

The 4th day was for the last presentations and general discussion about the future plans for IIES. During the meeting we also had a possibility to visit UEF/ILMARI aerosol physics, chemistry and toxicology research unit and UEF/Savonia University of applied sciences water laboratory at Kuopio Science Park. Long days, hard work, but also fruitful discussions and new contacts for future research.

Those who are interested can read more about IIES here:

http://www.uef.fi/en/web/iies-workshop-kuopio/iies

http://trentu.ca/iies/

The 3rd Annual IIES Scientific Workshop will be held in China in August 2017, hopefully with a growing number of participants and research topics on environmental sciences.

 

Text by: Kaisa Figueiredo

Photos by: Yu Zhang/Timo Kumlin, Kaisa Figueiredo, Kristiina Väänänen