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Thursday, 10 April 2014

My Second Fieldwork in University - Pond

Just came back from a three-day escape from university (but this does not mean that we ran away successfully from all the reports, boohoo) and found that I left out this post for quite some time. So before I write the following posts about this three-day escape, I decided that I better quickly finish this one first.

Scenery in front of our faculty.
The Faculty of Environmental Studies actually covers quite a large area with a few distant buildings unlike most of the other faculties where all the blocks cluster together. This fieldwork was carried out at the pond in front of our building for Environmental Forensic which we rarely went there now as first year students. This time we went there to do know more about the photosynthesis of aquatic system by the green algae.

Firstly we measured the light penetration of sunlight through the pond surface using secci disc, a black and white plate which we place into water to determine light penetration through its visibility. It should be done twice in two ways: slowly lower it down the water from the surface and slowly lifting it up in the water from the depth where you can't see the disc. Then get the average value of the depths. That will be the depth where light can reach. Beyond the depth there will be no light penetration and photosynthesis rate would be minimum.

The floating platform that we used for the fieldwork instead of using boat.
Next we measured the photosynthesis rate of the green algae in the pond by collecting water samples at three different depths: 0.1m, 0.5m and 1.0m. From each depth we collected three bottles of samples, one for in situ measurement of dissolved oxygen, the other one in transparent glass bottle and in amber bottle which is dark in colour. Both of the bottles were tied onto a pole at the position of its original depth marked on the pole. Since there were three depths, in total there were six bottles being tied to a pole. The pole was placed into the pond where the bottles would be at their original depths and it was fixed on the floating platform. Oh about how to collect water at specific depth, we used pump, hehe. We should fully utilise the technology we have, or else we would have to dive into the water. Hahaha.

In situ measurement of dissolved oxygen (DO).
Actually we should pull a string across the pond to the other side and set up poles along the string so that the data obtained can represent the data of the whole pond instead of just one corner of the pond. Besides that, we had done some careless mistakes which caused us to have inaccurate results. We were unaware of the movement of the sun position. As we had to leave the bottles in the pond for two hours, after fixing the poles onto the floating platform all of us left and stayed at shady places under the trees. After awhile the shadow of the platform somehow covered the poles from sunlight, which means all of the bottles will receive no sunlight. So the depths and clear or dark bottles would not be the manipulated variables since the condition was the same for all the bottles. Moreover, as soon as all the students left the platform, the weight exerted on the platform was removed. So the platform raised back to its initial position, so did all the poles.

So this experiment could be considered as a total failure. Planning should be done before doing any fieldwork to save time and energy so that no redo has to be done. Anyway, this was a nice experience too to prepare us and give us lessons so that we can improve next time when facing bigger challenges. Up next, the largest fieldwork of our first year study! Stay tuned!

Me and my crazy coursemate.

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