Aihearkisto: Research

Sediment field clean-up trial, Part 2: setting up and monitoring the actual field trial

In Part 1 of this Blog post we took a look at the on-site sediment remediation with activated carbon. Now we will gain a small insight to the first field trial of the method in Finland, which was started by our group in August 2015.

The test site lies in Lake Kernaalanjärvi, which was contaminated with PCBs between 1956 and 1984. There was a steady, unnoticed discharge of the chemicals from a paper mill upstream one of the lake’s feeding rivers (Tervajoki). Since no one noticed that leak for so long, quite an amount was released to the river and ended up in the lake eventually. The fact that this is still a problem nowadays, even though the leak was shut down over 30 years ago, gives you a hint on the persistency of PCBs in the environment.

Lake Kernaalanjärvi, the site of the field test in winter (Plot marked). The feeding Tervajoki River – the source of the pollutants (PCBs) in the lake – is nicely visible.
Lake Kernaalanjärvi, the site of the field test in winter (Plot marked). The feeding Tervajoki River – the source of the pollutants (PCBs) in the lake – is nicely visible.

Since the lab trials had not only shown the high efficiency of activated carbon, but also potential risks of the sorbent particles themselves, we applied it only to a small plot of 300 m2 within the lake. This way we don’t mess up a whole lake, if the side effects are bad, but we also don’t waste too much money, if the clean-up potential is not as good as seen in the lab. The plot lies in the south end of the lake – the most contaminated area. This is right where the contaminated feeding river enters into the lake (see satellite image). With it come the PCBs, usually attached to suspended particles that settle as sediment once the water flow speed gets low enough.

For the remediation works, we ordered about 1000 kg of pressed pellets consisting of activated carbon and clay (Sedimite™). The latter increases the density of the pellets, making them sink faster to the bottom of the lake. This fast-sinking property makes handling and applying the activated carbon really easy. You can basically just shovel them out of a boat onto the water surface and they sink straight down onto the sediment. With pure activated carbon – usually a powder – that would be unthinkable. In part 1 of this post you could see a picture of the mess we can easily create already in the lab when we handle activated carbon powder. Add a bit of wind or rain (which we rarely see in the lab) to that and you might not have the greatest work day of your life. Even if the powder finally reaches the water, most of it would just get suspended in the water column and settle after days at wherever the water flow brought it.

The boat is loaded with activated carbon pellets (Sedimite™) – we’re ready to get going!
The boat is loaded with activated carbon pellets (Sedimite™) – we’re ready to get going!

For the application of activated carbon we had to first of all change our “lab rat” attitude to field-trial-mode: In the lab, we usually work with precisely measured doses, carefully applied in controlled environments. In the field, we had to take more of a “rough estimate” approach. We started by measuring a 10 x 30 m field on the lake, marking it with buoys and ropes. For better orientation and to achieve a more even layer of activated carbon, we diverted the plot into 5 x 5 m intersections, which were handled one at a time. After we had applied (read: shoveled) all of the pellets onto the test site, we took some sediment core samples of the freshly covered site. Luckily we could see that the pellets had actually worked as intended and we achieved a quite good layer of activated carbon on top of the sediment.

Applying the pellets to the marked plot on an average Finnish summer day.
Applying the pellets to the marked plot on an average Finnish summer day.

Now – about one year later – we checked in to see how the field looks like. We took core samples on the same spots again and unsurprisingly, the field looks a lot different. Wind and waves have affected the plot heavily:  a lot the sorbent has been swept away. In addition, a thick layer of new sediment has covered what was left on site.

Sediment core samples showing the applied layer of activated carbon one day after the plot setup and 10 months later.
Sediment core samples showing the applied layer of activated carbon one day after the plot setup and 10 months later.

How this is affecting the remediation potential and the adverse effects of activated carbon, we plan to find out in the near future. We have scheduled a lot of monitoring works, such as surveys on the condition of the local sediment fauna and changes in the PCB uptake by the organisms living on our plot.

Important part of every exhausting field trip: Beer and Sauna.
Important part of every exhausting field trip: Beer and Sauna.

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

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

Here we go again – Many steps to an experiment on black worms

After a year as a teacher I came back to research in aquatic ecotoxicology. I’ll test a method to analyze fullerene nanoparticles in separated tissue fractions of black worms. Simply, I’ll expose the worms to fullerenes, collect organisms, fractionate their tissues, and then measure fullerene concentrations in each tissue fraction. But starting a new experiment requires a plenty of preparations in the lab before actual test can be started. Here I tell what is going on during the first two weeks.

I would need a test sediment treated with fullerenes. For the test sediment, I would need fullerenes suspended to water to be added to a natural sediment from Lake Höytiäinen. Luckily, we already had the sediment in our lab… if we didn’t have, I would have to wait for winter to go to the field and collect it through ice… I would also need my test species, black worms, synchronized to similar physiological condition.

Sediment sampling. Pictures by Kristiina Väänänen and Jarkko Akkanen
Sediment sampling during winter time.

As a very first job, I prepared artificial freshwater, which means a lab-made model of fresh water corresponding “average Finnish freshwater” with its hardness. Then, I used that water to suspend fullerenes. Making fullerene suspension takes time: fullerene powder must be vigorously mixed with water for two weeks before it can be used in the experiment. This mixing process must be done because fullerenes are not soluble in water, but they turn to water-stabile form via water flows and mixing. And when thinking about fullerenes’ fate in natural waters, they can enter to the environment e.g. in waste waters. Thus, water suspension is their first step to bottom sediments. Read more about fullerenes’ environmental fate here: http://onlinelibrary.wiley.com/doi/10.1002/etc.2175/full

Fullerene suspension, picture by Kukka Pakarinen
Fullerene suspension.

Black worms are sediment-dwelling benthic worms. They have important ecological roles in aquatic ecosystems as a food source for fish and as decomposers of sediment material. They can be exposed to fullerenes via wasted sediments. In this experiment I’ll need size-synchronized worms, as some other researchers in our group. That’s why we organized “a worm cutting day” to synchronize more than thousand worms. It means that four of us sat a day in the culture room picking worms from their aquariums to petri dishes, and then separating their head parts and tail parts by a surgeon knife: the head parts grow new tails and tail parts grow new heads. How to identify which part is which? Color of the head is a bit black and thicker whereas the tail is red and thinner. Then, we’ll wait for couple of weeks to let the worms create these new parts. Finally, we’ll get test worms with same size and condition. Dividing to heads and tails is also a normal way to reproduce for the black worms. Read more about fullerene-exposed black worms here: http://www.sciencedirect.com/science/article/pii/S0269749111003848

Worm cutting day
Worm cutting day
Head part, tail part and cutting
Head part, tail part and cutting

While fullerene suspension and the worms are underway, I can do some other preparations. Sediment dry weight must be known to adjust volume of fullerene suspension. Preparations for the dry weight could be favorite job for kids: wet sediment is homogenized with a perforated piston before samples are placed to weighing jars and dried.

Mixing and weighing the sediments
Mixing and weighing the sediments

Next week it’s time to measure fullerene concentration in the suspension, add fullerenes to sediment and let them stay to equilibrate before the experiment.

Text by Kukka Pakarinen

Pictures by Jarkko Akkanen, Kristiina Väänänen, Kukka Pakarinen, and Risto Pöhö

Hands-on research with Chironomus riparius

Sitting in the lab in front of a sewing machine was not exactly what I imagined of doing when I started my PhD in the group of aquatic ecotoxicology. However, sewing two hundred miniature mosquito nets was required before I finished my thesis.

Inna and Greta sewing mosquito nets. Photo by Inna Nybom
Inna and Greta sewing mosquito nets. Photo by Inna Nybom

My PhD relates to activated carbon, porous carbon material, which has been studied as a new remediation method for contaminated water ecosystems. Due to its wide surface area, activated carbon can bind numerous contaminants efficiently and lock them in the bottom sediments in a way that they are now longer available for organisms living in the area. Reduced bioavailability of the contaminants for benthic organisms reduces also their transport in the food chain and in time this can reduce the contaminant load to humans from fish consumption. However, both old and new remediation methods, where something is removed or added to the natural ecosystem, can disturb the balance in the field, at least temporarily. Therefore, in this study also direct adverse effects of activated carbon to the benthic organisms were followed.

In our resent work the effects of activated carbon were studied on midge Chironomus riparius. Chironomus riparius is a nonbiting midge, with a four-stage life cycle: egg, larva, pupa and adult midge. Larvae is living in the sediment, and they were grown in activated carbon containing contaminated sediment. After few weeks the larvae develops to flying adult stage, and this is where the mosquito nets come in handy. In order to follow the effects of different exposures to the adult stages, 180 small beakers were sorted on the table and covered with individual mosquito nets, food was provided three times a week and all beakers were monitored daily. All the effort payed off when we finally got the results! We observed that adding activated carbon to the sediment reduces the contamination level not only in the larvae stages but also in the flying adult stages exposed during the larvae stage. We know that the aquatic insects going through metamorphosis can transport the contaminants buried in the bottom sediments to the terrestrial food webs, and our result indicates that adding activated carbon to the sediment may reduce this transport of contaminants! Amongst this we discovered many other cool things, which are published in details in Environmental Science and Technology (2016, 50[10] 5252–5260, DOI: 10.1021/acs.est.6b00991). Check it out, if you are interested in finding out more!

A life cycle of Chironomus riparius
A life cycle of Chironomus riparius. Photo by Inna Nybom

I had a great time working in the croup of aquatic ecotoxicology, but now new adventures are ahead. My PhD project came to an end on December last year when I defended my thesis. The most I am going to miss all the great people I got to work with. A great group of excellent scientist with a catching enthusiasm, innovative to come up with the ideas of 200 miniature mosquito nets, and crazy enough to actually sew them with you!

JUFO = Journal, an unidentified flying object

Julkaisufoorumin etusivulla lukee näin: ”Julkaisufoorumi on suomalaisen tiedeyhteisön toteuttama, tutkimuksen laadunarviointia tukeva julkaisukanavien tasoluokitus”. Harvoin on tiedeyhteisön toteuttama asia onnistunut aiheuttamaan omassa tiedeyhteisössäni ja muissa kollegoissani yhtä paljon nurinaa, hammastenkiristelyä, vitsailua sekä naureskelua kuin tässä tapauksessa. Luettuani viimeisimmän Acatiimi-lehden huomasin, että hämmästely ei ole rajoittunut pelkästään meidän tieteenalallemme. Sinänsä ymmärrän kyllä tarkoitusperät, koska JUFO-luokitus toimii ohjaavana tekijänä, kun yliopistot ja niiden yksiköt saavat rahoitusta tieteellisistä julkaisuista. Enää rahoitus ei siis riipu pelkästään julkaisujen määrästä vaan myös laadusta.

Julkaisufoorumin on siis luokitellut suuren määrän tieteellisiä julkaisusarjoja. Luokassa 3 ovat jokaisen tieteenalan huippusarjat, luokassa 2 on johtavat, luokassa 1 perustasoiset (tähän kuuluu kansallisiakin sarjoja) ja sitten on vielä ym. sarjat. Ilmeisen monessa tapauksessa on kuitenkin menty pieleen, sen verran luokitus on keskustelua aiheuttanut. Olin myös luullut, että järjestelmä vähentäisi tieteenalojen välisiä eroja julkaisujen tasoa arvioitaessa….no, eihän sitä voi käyttää tieteenalojen väliseen vertailuun. Ymmärrän sen, kun tieteenalan sisälläkään julkaisusarjoja saada sellaiseen järjestykseen, että se vaikuttaisi kansainvälisen tiedeyhteisön mielestä järkevältä.

Esimerkkinä voin kertoa erään tapauksen omasta tutkimusryhmästä. Olimme tarjonneet erästä tutkimusryhmämme kansainvälisenä yhteistyönä kirjoitettua artikkelia oman alamme johtavaan lehteen (JUFO-2). Ei kelvannut sinne, joten mietimme seuraavaa siirtoa. Ehdotimme kansainvälisille yhteiskumppaneille erästä toista julkaisusarjaa. Se ei kuitenkaan aiheuttanut suuria intohimoja, totesivat vain, että ihan hyvä, mutta entäpä tämä ja tämä. No, minä sitten selitin, että sarjat tämä ja tämä ovat JUFO-1 luokassa ja se meidän ehdottamani on JUFO-3. vastauksena viesti, jossa kirjoitettiin ”ha ha ha, onko UEF:n rehtori kyseisen sarjan editori?”. Kerroin luokituksen olevan valtakunnallisen ja toki luokituksen taustat sekä myös miten se liittyy meidän saamaan rahoitukseen. Tällöin tyytyivät valintaamme. Teimme itse asiassa jo kerran samoin viime vuonna. Yritimme JUFO-2 sarjaan, ei kelvannut sinne, mutta lopputulemana julkaisu JUFO-3 sarjassa. Tätä kirjoittaessa ei ole vielä tiedossa, kelpaako tämän kertainen käsikirjoitus siihen JUFO-3 luokituksen saaneeseen sarjaan. Toisena esimerkkinä voi toimia tällä hetkellä ulkomailla työskentelevä suomalainen kollega, joka totesi yhteisjulkaisuumme sopivaa sarja mietittäessä, että hänen on mietittävä ihan jotain muuta kuin JUFO-luokituta. Ymmärrän hyvin, koska meidän JUFO-luokituksemme ei liene kansainvälisesti kovin tunnettu.

Julkaisufoorumillehan voi esittää tason muutoksia, jos siltä tuntuu. Ei välttämättä tunnu, jos kerran sinne JUFO-3 lehteen jutut menevät helpommin läpi. Sitä paitsi eiköhän tämäkin korjaannu ja kaikki meidän tieteenalan lehdet valu sinne 1-luokkaan kun tasoja tarkistetaan tulevaisuudessa. Saavatpahan kansainväliset yhteistyökumppanit lisää naureskeltavaa, kun seuraavan kerran taas valitaan sarjoja, joissa yhteistyönä tehtyjä käsikirjoituksia yritetään saada julkaistuksi. No, voi olla turhaa nurinaa ja kateellisten panettelua. Pitää kai vain nostaa oman tutkimuksen tasoa luokituksen muuttuessa, mutta kuten tiedämme, (J)UFOt osaavat olla arvaamattomia. Eivätkä kaikki ole edes sitä mieltä, että niitä on olemassa.

A time with microplastic, Daphnia and winter in Finland

My name is Meaw. I come from Thailand, the small tropical country in Asia. I got scholarship from Erasmus Mundus action 2 (SWAP and Transfer project) to do the research about microplastic in freshwater ecosystem for 6 months. I’m interested in microplastic because it’s a pollutant with emerging concern and there are many gaps in research about microplastic. I have done many surveys on microplastic in Thai coastal area, but in here I focus on microplastic testing with aquatic animal in laboratory.

Microplastic and Daphnia

I lived in Finland from Dec 2015-May 2016. During that time, I tried to feed daphnia with fiber microplastic and observe the uptake and depuration behavior of daphnia. In our lab, it is very easy to do the test with daphnia, because the facility is well preparation. So that it is very convenient to do the thing as I plan, even if I did not have an experience with daphnia before.

I also have an opportunity to work together with Spectromics research group in UEF, because we try to develop the technique for observation microplastic inside daphnia. I am very happy to have chance to discuss and share the ideas with the other researchers in our lab group and Spectromics research group. That’s very challenging for me.

Daphnia magna and microplastics
Daphnia magna and microplastics

Winter in Finland

By the way, because I arrived Finland in winter, I had been asked a lot that “why I come to Finland in winter time?” Actually I did not think about it before I came. Anyway, after one week past I just realized that why everyone asked me. Snow and ice is such normal things in Finland winter and rarely sunshine at that time. It’s very exciting experience for people from tropical country like me. The winter in Finland is longer and colder than in my imagination. That’s why I always ask everyone in the lab “Is it normal weather in Finland?” and now I know that’s normal, after I passed through nearly 4 months of Finnish winter. Even whether in winter make some difficulty of life, but I think that’s worth to get experience like that. I think if I did not stay in Finland at the winter time, I may not see and understand the real Finland. So if someone ask me what the best period to visit Finland, I will recommend winter. Do you agree with me?

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13 June 2016, Meaw