Thursday, February 25, 2010

Water quality monitoring (WQM) projects on the rise?

It is heartening to see more schools (secondary and pre-U) getting into water quality monitoring (WQM), based on the queries coming in from teaching staff and students. This is especially encouraging given the lack of publicity and media coverage on WQM.

I will truly be happy when I see the same trend in research and innovation funds going into WQM. On the positive side, there is already an observable rise in interest in environmental issues, the most obvious star being climate change with all its implications.

Much money has also been poured into water - not WQM of course but on water and wastewater treatment. In the context of Singapore, this is understandable as water has always been an issue of national security. Wastewater treatment may seem to to be a poor cousin of water supply but it is NOT. Without it, Singapore will likely be infested with filthy waterways and crippled by rampant waterborne diseases. (I suddenly remember this analogous joke about our bottom orifice being the boss among all the other body parts. When it refused to work and shut down (literally), the brain, heart, stomach etc. went into panic and finally acknowledged it as the boss.)

Hopefully, we will start to recognise the role WQM plays in our water supply. Water does not only come from rain dropping into the reservoir directly. It comes from the watershed serving the reservoir. In Singapore's case, the watershed can extend to quite a large area serviced by a network of canals running into the reservoir. Oh well, perhaps one step at a time.

I have copied an excerpt of a recent query below together with my reply. Perhaps some of you may find it useful. (I have of course omitted names of persons and schools in my excerpt.)

We are a group of 3 students from (omitted) currently preparing to embark on a water quality project by assessing the macroinvertebrates in water body. The two main water bodies we are looking at are WELL stream and a canal in Hort Park.

After looking at your blog, we discovered a lot of useful information that can help us with our project. There are a few problems we hope you can clarify for us.

Firstly, we are unsure about the period needed to monitor the macroinvertebrates in order for the results to be accurate.

Also, we are not very sure about the suitable methodology to monitor the macroinvertebrates as we are strongly discouraged to remove macroinvertebrate from the water bodies. Currently we are thinking about scooping the macroinvertebrates out of the water body to observe, before putting them back since the canal and stream are relatively shallow and the kick-seine method is not practical. The problem with this is that the stream may flow too fast for us to count the macroinvertebrates correctly.

We really want a guidesheet and would like to enquire if you have a guidesheet for identifying macroinvertebrates. Due to short dateline, we would only pick on one species to observe, which we would only decide after going to the actual sites.


Good to see that you are interested in the bugs in our waters.

A few points from me:

What is your objective of assessing the bugs in your chosen water bodies? Do you have a hypothesis to prove or disprove?

Monitoring period
This depends on your answer to point 1.

E.g. if you are trying to find out the effects of day/night on the bug community, then you probably have sample in the morning, afternoon, evening, after midnight.

Or are you trying to correlate some other parameter to the bug community?

This will be tricky if you do not want to remove any bugs from the environment. Sorting and counting will be impossible without bringing the bugs out of the water though I believe it is possible to sort/count on site as your suggested (the bugs will still have to be removed from the water environment).

However, the method you suggested (scoping out and putting back) may not work too well if you do not stir up the bottom sediments. Most bugs are found in the sediment.

Being not familiar with the locations you mentioned, I am not sure why you said that the kick seine method is not practical as it can still be used in shallow waters. Other methods include the Surber sampler, colonisation samplers (leaving something in the water for bugs to colonise) and drift sampler. Colonisation sampling and drift sampling do not require kicking and have a good chance of yielding a signicant number of bugs.

I suggest that you restrict yourself to Order level for identification rather than species level as it is difficult to even go to Family level in the field. A good guidesheet is the Aquatic key sold at Nature Niche. It is designed for Thailand's bugs though it should still work well here. Check if they have stock. If not, you may borrow from me.

Thursday, February 04, 2010

Going, going, gone - the end of Ngee Ann Stream (almost)

In preparation of a coming course on water quality, I went back to my favourite stream for a recce yesterday.

First time I ever saw an excavator clearing debris and aquatic plants from the stream though this should not be surprising. The stream often is muddy and overgrown with Hydrilla. Someone has to maintain and clear the channel for storm water collected in the Bukit Timah area to flow all the way to Pandan Reservoir.

The riparian zone next to the stream in the secondary forest has been completely cleared.

This was taken in 2008, showing the same patch of land (then forested)beyond the railway track.

The riffles are now under a wooden bridge for trucks. Both sides of the stream are not spared.

The riffles as they were in 2009.

Remainder of the secondary forest... waiting to be cleared

Even the belukar was turned into a nice field.

The beluka as it was in 2009.

A large patch of land was already cleared when this satellite photo was taken but even the small sliver of secondary forest (in red outline) bordering the stream is now gone.

I guess the property hunters will soon have another condominium to fight over.

As given in the URA Master Plan 2008, this area is planned for residential purpose.

As for me, I will continue using Ngee Ann Stream as my living classroom though I will have to alter my teaching route and miss out the wonderful shade and undulating terrain of the secondary forest.

Tuesday, February 02, 2010

Is acidity a problem in streams of Bukit Timah Nature Reserve (BTNR)?

This is in response to the Straits Times article "Native species in Singapore may be wiped out by acid rain" (14 Sep 09) (I must have somehow missed it last year :-), the reply from Nparks and a recent comment.

BTNR has always held deep memories for me in water quality monitoring as this was where it all started in 2006.

These past few years, the pH of the 3 streams I monitored have indeed been acidic, fluctuating around 3 to 5, with a few instances of 2+ and one instance of 1+ in 2007. Though some websites mentioned that the pH used to be higher in the 1990s, I could find no documentation about this.

The big question is: is this bad for the water inhabitants e.g. crabs, fish? Hard to say. Most literature will insist that such low pH is unthinkable for aquatic lifeforms to thrive or even survive. However, many reports have surfaced about discovering rare and endemic species living in acidic waters with a pH as low as 3. You just need to give living things time to adapt (and evolve?) and they should fit in eventually.

Then the question becomes: has the acidity in BTNR always been like this? We are now back to historical records which are hard to come by.

Nevertheless, here are some possible explanations to the low pH in BTNR (regardless of whether it harms the wildlife there).
  1. Acid rain
    From reports, acid rain generally does not lower the water pH below 4. An accomplice maybe but hardly the main perpetrator.
  2. Decomposing vegetation
    Ah... this sounds like a more likely culprit. Decomposing vegetation can give rise to humic and tannic acids. These dark brown substances produce the well known black waters in the Amazon and the acidic peat swamps in Sumatra and Borneo. Still, they do not generally cause the pH to go below 3.
  3. Acid mine drainageThis can be a real killer. Sulphur or sulphide bearing ore from underground deposits are somehow brought to the surface and oxidised into sulphuric acid. This CAN really depress the pH to deadly levels.
  4. GeologySimilar to acid mine drainage, certain volcanic streams and lakes (probably having the same origins of sulphur or sulphide in the geology) can push the pH down below 1.
  5. PollutionAnd yes, if you dump acids right into the stream, you can get very high acidity.
1 and 2 appear unlikely in view of the low pH in BTNR. I suppose 5 is out too unless some lunatic is dumping acids at the peak of BTNR.

If BTNR has sulphur or sulphide underground, this certainly is interesting. Has anyone done any geological analysis there?

Then I have a new question if it turns out that the pH used to be higher in the last decade: what has happened that causes the sulphur/sulphide to oxidise into sulphuric acid in this decade?

Till the guys at Nparks and NUS finish their investigation, I guess we just wait and see for the results.

Jungle Fall Path stream

Seraya Loop stream

Rock Path stream