Monday, October 25, 2010

Outdoor Education Conference (27 Oct 2010)

For those of you heading to this conference (walk-in registration is still available), you may be interested to know that I am presenting 2 sessions on 27 Oct 2010 (Wed).

Details for the concurrent sessions are as follows.


Water Quality Monitoring as a Tool for Environmental Education27 Oct09:00am-11:00amMr Kwok Chen Ko Singapore Polytechnic, SingaporeB08-09

Water Quality Monitoring as a Tool for Environmental Education27 Oct11:30am-12:30pmMr Kwok Chen Ko Singapore Polytechnic, SingaporeB08-09

1. Appreciate the importance of water quality to the health of the environment

2. Understand how several fundamental water quality parameters interact with aquatic life
3. Recognise the potential and challenges to water quality monitoring in Singapore

Target audience
Teachers/ Practitioners/ Coordinators of outdoor education programmes

Brief Description of SessionBesides the usual classroom talk on water quality monitoring, we will go through some of the instruments used in the field via a demonstration.
1. What is water quality
2. The basic water quality parameters
3. Measuring these parameters in the field
4. Challenges to water quality monitoring in Singapore
5. Resources for water quality monitoring

Sunday, October 10, 2010

Is Pasir Ris water really unsafe?

As a follow-up to the news update on the fecal bacteria laden water of Pasir Ris, this news may throw more questions (instead of light) on the issue of poor water quality at Pasir Ris.

First, a quick summary. A press release from NEA (Sep 2010) stated that the water at Pasir Ris Beach is unsafe due to the off-specs level of Enterococcus (a bacteria) in the water. Enterococcus is supposed to indicate the level of fecal contamination. More Enterococcus of course means more fecal contamination, implying a higher possibility of the presence of human pathogens.

Why don't we analyse the water directly for the pathogens? There are simply too many pathogens to test for so going down this route will easily lead to a logistical nightmare. Therefore, we stick to an indicator organism, something that is strongly linked to humans. Since Enterococcus (supposedly) comes from the human gut, its presence is (supposedly) sufficient to prove the contamination of the water by humans.

Going back a bit backwards in the history of water quality testing, the title of indicator organism for fecal contamination used by held by a group of bacteria known as coliforms. Not surprisingly, coliforms are also found in the human gut and its presence used to conclude the presence of human contamination. Unfortunately, coliforms are also found in other animals and soil. Some years back, Enterococcus has taken over this position as it was found to produce a better correlation to many human pathogens found in sewage. (Opps, the summary seems a bit longer than I initially thought.)

Ok, enough of summarising. Check these out:
1. Evaluation of Chemical, Molecular, and Traditional Markers of Fecal Contamination in an Effluent Dominated Urban Stream

2. How To Define "Safe" Water? Water Pollution: Southern California study highlights the limits of bacteria used as fecal indicators

The study basically argues that even Enterococcus is not a good enough indicator for fecal contamination in water. Why? Because it can also be found naturally in the river bed (in the study). In fact, it can actually grow in the river bed under favourable conditions i.e. good nutrient availability. Therefore, a bacterial count using Enterococcus tends to be overestimated with regards to the actual fecal contamination. (Granted, the study took place in fresh water and not seawater. But being such a versatile creature, Enterococcus can tolerate a wide range of conditions - pH, temperature, salinity, presence/absence of oxygen so it will not be surprising to find it thriving nicely in seawater.)

Is the water at Pasir Ris safe then? Your guess is as good as mine.

However, the study did recommend a substitutre for Enterococcus - something known as human-specific HF183 Bacteroides. This bacteria is supposedly (?) found only in the human gut. Testing for the presence of its genetic material will provide an accurate (?) picture of the amount of fecal contamination in water.

Will it really work?

Me? I will wait for the next piece of study to throw a spanner into this theory :-)

Friday, October 08, 2010

Digging around at Pandan Reservoir

I managed to steal some rare spare time to tag along with a NUS team and JH for a biodiversity survey of the floating wetlands at Pandan Reservoir.
What floating wetlands?!? If you have been observant enough, Pandan Reservoir and Lower Seletar Reservoirs have several bunches of plants floating right in the water. No, they are not aquatic weeds that suddenly grow up from the reservoir bed. They were deliberately placed there as an experiment(?) to improve the water quality. (Check out my previous post on how plants can clean up water.)

Figure: One of the floating wetlands at Pandan Reservoir. Notice that the plants on the wetland are different from those on the shore.

These floating wetlands are actually made of a floating plastic matrix above which a layer of coconut husks is embedded. The plants are allowed to extend their roots through these 2 layers.

Will they float away? No. Short of an extreme weather event, each wetland is anchored to the bed by rocks.

These floating wetlands dotted the northern shore of Pandan Reservoir. Are they effective in improving the water quality? My opinion is there are probably too few of such wetlands to make a difference to the reservoir as a whole. (Did I say that this was just an experiment?) Any change in water quality is probably localised and restricted to the immediate vicinity of the wetland. You will likely need a series of these wetlands to ring the entire reservoir. Maybe add another ring or two.

Figure: By the way, we had the luxury of sitting in a PUB motorboat as we passed by several floating wetlands

Next question - do bugs (macroinvertebrates) live under these wetlands? If so, what kind of bugs? These are interesting questions as my usual bug surveys were performed in running water (e.g. stream) or stationary water (e.g. pond). In the substrate of a floating wetland?!? No one knows...

Figure: Digging and scrapping and sweeping through the underside of a floating wetland

Figure: Voila! You can see a Marble Goby (top left) and a shrimp (bottom right) clearly here.

No so clear in the figure include: backswimmers (many!), unknown zooplankton (?) (many!), copepods, chironomids (your wriggling blood worms), a few damsel flies, dragonfly nymph exoskeletons (surprisingly, no live nymphs though we can see adult dragonflies happily scuttling through the air), chironomid eggs and pupa cases, mayflies (!). Looks like the biodiversity in these floating wetlands ain't so bad.

Figure: No, this is not part of the wetland survey. Actually, this is the primary task of the NUS team - deploying sampling traps in the reservoir to find out what kind of bugs can be lured into them.

Figure: On the way back, we stopped by this odd looking contraption floating in the middle of the reservoir. (Actually, it a buoy housing sensors though no one in the team knows what kind of sensors.) Of course, data from the sensors are transmitted telemetrically to some receiver on shore. Everything is this package is powered by solar energy as evident by the solar panels. See a previous post on descriptions of a similar setup. Oh, we didn't stop here just to admire this blue box. The NUS team actually wanted to catch some spider specimens here as a healthy population of spiders seems to be thriving on this buoy in the middle of nowhere.