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Thursday, 17 April 2014

Tasik Chini Fieldwork - Environmental Forensic (part two)

Assoc. Prof. Dr. Ahmad Zaharin whom we first met although we have heard of him from seniors. He is unexpectedly young, hahaha. 
Everyone was nervous when going for this session. We were greeted with good luck and 'be creative' by the time we proceeded to this session by the previous group. How could we be not nervous? Haha. When we reached the floating platform at the middle of the lake (that was the place where we boarded speedboat for other sessions), we were given no instruction and were straight away asked to demonstrate the ways to collect samples according to a case given. We had a lecture and a practical about water sampling before we came to this fieldtrip but obviously we forgot almost everything (feeling regretted that I did not write down notes during the practical). Marks will be deducted for each mistake we made (and guess what, at the end we lost 80 marks, as expected, haha).

As we were struggling with the sampling, Dr. Zaharin told us how important Environmental Forensic is. Environmental Forensic is similar to forensic science which is about collecting and analysing the data related to crime etc. but it is more about the environment especially pollutions. The samples which are also the evidences are collected so that accusation can be made against the party who has polluted the environment. However we seldom hear about cases related to the environment pollution or destruction in Malaysia. I had taken an online course named 'Introduction to Environmental Law' last semester break and found that the United States has a lot of case laws and information regarding the environmental issues which we can refer to (how I wish I could learn more about cases in Malaysia).

So back to the topic. What we did in this session was about water sampling. It sounds easy, but it made us lose 80 marks within that one hour. Basically we use three types of bottles for water sampling: Firstly, the glass bottle with blue cap (the colour carries meaning but I am not sure, there is a variety of colours for caps of glass bottle). It is mainly used to collect water sample for the analysis of microorganisms. To make sure that no other microorganisms other than the one from the sample enters the bottle, the mouth of the bottle should we heated using Bunsen burner to kill any possible microorganism from the air (we heat only the mouth of the bottle as the inside of the bottle should be clean and dry before any sampling process, only the mouth might be in contact with the air). Secondly, the amber bottle which is dark brown in colour with a glass stopper. It is mainly used to store water sample for the analysis of the nutrient contents or any oxygen related analysis (dissolved oxygen, biochemical oxygen demand etc.) and to stop the photosynthesis process of algae. The bottle should be held by two fingers at the neck (thumb and ring finger) while the cap should be held by the other two fingers (index finger and middle finger) of the same hand (and you know glass bottle is heavy)! We avoid having skin contact with the body of the bottle so that our body heat will not affect the quality of the sample. Thirdly, the polyethylene bottle (plastic bottle which is very expensive, similar to the one which keeps medicine given by the clinics). It is mainly used to carry water sample for metal ion analysis.

The Ven Dorn Sampler.
There are so so much standard rules that we have to follow when collecting samples or else the samples can be considered as invalid. Here are some of the rules:

  • The sample bottles are stored in ice at 4 degree Celsius to slow down any biological or chemical reaction.
  • We use a 0.45 micrometer filter to remove microorganisms from the sample under certain conditions.
  • Some samples have to be acidify to kill microorganisms or to maintain the stable state of metal ions.
  • Some chemicals might need to be added into the sample to maintain its original quality (we did not learn much about this so far).
  • The sampling process should not be carried out under the sun as the sunlight might affect the samples.
  • There should not be air bubbles in the bottle (or air gap between the sample and the cap) to avoid the escape of gas particles from the sample into the air space.
  • The sample should be collected using the sample bottle straight away if possible. If we transfer the sample from the collecting device (such as the Van Dorn sampler) to the sample bottle, we must make sure that the sample bottle is fully filled as we cannot transfer the sample for the second time into the bottle which already contains some amount of the sample to avoid contamination.
  • If we are going to test the pH value of the sample, the sample should be shot at the inner wall of the sample bottle so that it will flow down the wall and eventually filling up the bottle to avoid any addition of gas into the water.
  • The sample bottle should not be rinsed using the sample before collecting the sample as it should be clean and free from any contaminant before sampling process.
  • When collecting water sample of a river, we should do so at different distances from the source of the pollution by carefully submerging the bottle at least 10cm below the surface. The mouth of the bottle should be pointing at the direction of the river flow.
  • When collecting water sample of a pond, we should do so at moving water instead of stagnant one so that the sample can represent the overall condition of the pond. The samples are collected at different depths.
  • When collecting water sample from a water tap, the tap water should be allowed to run for a few minutes to remove stagnant water in the plumbing network.
  • When collecting water sample of groundwater, the pump should be operated for some time (according to the depth and diameter of the pipework) to flush out stagnant water from the pipe. Sample should not be collected from newly drilled or rarely used well.
  • We must avoid any disturbance (scraping or stirring) to the water bodies when sampling so that the quality of the sample collected is as original as at the sampling site.
  • Labelling is very important before the sample bottle is used to ensure that we do not confused over the content in the sample bottles.
After lowering the sampler into the water, a messenger (a small heavy cylindrical object) will be send towards the sampler down the rope and hit the switch so that both of the openings of the sampler will close. Cool, right?
There are a lot more that we have to keep in mind when sampling the water according to the guidelines. Mistake should not be done (at all) during water sampling as evidence in Environmental Forensic. Precision is essential for accurate analysis of the situation of the sampling site. It is something we really have to take seriously.

P/S: I have to do the part two first as I need to revise about the water sampling techniques. My coursemates will understand what I mean. Hehe...

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