Past Environment - Field work

Research topic, questions, hypothesis, methods need to be concretely defined before field work to make sure you get the most out of it

Pre-field work

Consider urban factors like heat islands in cities, local microclimates, try to reduce noise in your dataset
Patajärvi in Karelia drains sometimes, this would affect the data of course
In high flood events river channels can flow overland - if you're measuring river depth you need to make sure you're measuring from a good place

Planning a schedule and time table
Storage of the samples
- If you keep them in a warm bottle some biological activity might happen, changing chemical composition
- They need to be in good shape when you return to the lab
Pre-filling a notebook (make the tables before hand) is a really good idea. Physical notes are also good. Especially if it's very cold out.
- Make notes of things like the sample being tilted a bit, anything unusual about the sample so you can remember years later when you analyze it.
- Also write down where the samples are stored

This depends on your research question
Minimizing errors is very important - wash the equipment properly, test the equipment beforehand, service it

Rigorous planning and execution of your plan is essential - you are collecting data that you will be using for years after this
Be aware of your own resources and try to cooperate/collaborate with others
- Nowadays there are less new research ideas that nobody else has tried
- Important to look around in journals and databases to make sure nobody else has does it
- Palaeoecology symposium has a form for where you can share your field work plans and collaborate with others
  - You could send someone a bit of money in exchange for another sample from somewhere they are already going for more efficient use of resources

Take extensive photos of your study site also. Write down a visual description of the sites, write about the quality of the sample
Make sure your data is stored somewhere other than US-based cloud services which we could somehow lose access to

In the picture there are water moss stems which have contaminated the bottom of the sample. These likely got picked up at the top and mixed in.
- You can tell because they are on an angle through the strata - if they were old they would lay along the strata and it's outside along the edge of the sample.
- If it's green you can definitely throw it out

Avoid exposing samples to conditions that affect their quality
- Plastic bottles
- Light
- Temperature
- Moisture
- Drying out
Try to move it into a safe storage facility quickly
- Storage depends on the research question, but it could be freeze-drying, freezing, keeping in a +4deg dark room
- Chemical and bio-indicators can be done with freeze-dried samples
If you are using a box-corer with an open sampler in the spring or summertime, new pollen will contaminate your whole sample. WIntertime is the best for this type of sample

There are bands called "girdle bands" which should not be counted when identifying diatoms. One time a student mistakenly counted these, resulting in very different results
Quality control is very important, use reference material and internet mailing lists to reach out to international colleagues if you have a problem (diatom listserv)
Use regression (Linear models) and gradient analysis to interpret and simplify large datasets (Principal Component Analysis)

No analysis is better than the original sample

Depending on what you are studying you might need different classifications of devices

Piston corers (15m)
- first you drop the point onto the lake bottom then use a weight that you drop to push the barreol around the core, with the piston forming a gasket around it.
  !field_work, p.29
Russian peat corer
- A bit simpler and lighter
- Don't do it like in the video he showed where you pull the tube straight up since it can break off
- Rod can bend if you push a lot of weight on it and the water is deep, only good for 3 to 8-10 m maximum.
- A sudden transition between organic and inorganic sediment in the core like this is an indication of something strange happening:
  !field_work, p.35
Mackereth Corer
- For use in deep lakes - uses compressed air to drive a tube into the sediment that can be several years long
- Can be dangerous, safety is important
Uwitec corer
- same idea a bit, but it has this ball that seals the bottom over so you don't need to put your hand in the water.
- It also has a sampling device that allows you to take slices out of the core for sampling

Freeze corer
- in cold temperatures, it drives water in the edges and freezes it? Not sure exactly how it works
- Gives a seasonal variation in the output
Gravity corer - one common from Canada, another Swedish one (HTH-Kajak), they both work similarly to the piston corer (it seems to me)
- Rarely goes deeper than 30cm since it's hard to add enough weight. Also hard to lift this much sediment with just a rope
Sediment-Limnos - Finnish invention
- Surface sediment sampler
- A bit clumsy to use for subsampling
- Usually 0.5m long, some are 1m long. For short samples. You need a lot of weight on them to get deeper. You can also kind of "hammer" on the sediment by picking up and dropping the rope on the surface. Also doesn't work in deep lakes since the rope can get tangled on the way down

On Wednesday, we will use the Russian peat corer and HTH-Kajak. If we have room we might try the ice corer and Limnos