Overseas community service (OCS)/ Youth expedition project (YEP) part 3: Are there still more things to check if my water is safe?

This post follows from 2 previous posts.

1. Overseas community service (OCS)/ Youth expedition project (YEP) part 1: Is that water safe?
2. Overseas community service (OCS)/ Youth expedition project (YEP) part 2: How do I know if that water is safe?

So you have checked out your watershed and everything looks ok. No industries, agriculture or villages around. Are we home and dry?

NO! We have not checked out the history or to be more exact, the geographical history of the watershed! Find out what the area used to be...

2. Historical geography

Example 1: Mining
Mining (granite, coal, metals etc.) can especially be nasty to health and environment even after closing down for years. Digging deep into the earth can release toxic substances (lead, radiological compounds, heavy metals etc.) found underground into water once the mine fills up with water after closure. Not surprisingly, mining can also impact groundwater quality so those looking at using well water do take note as well.


Or sometimes, the mining operation itself left hazardous waste which remains uncleared after closure.

Google "toxic legacy of mining" and you can find tonnes of examples. Here are a couple.

1. http://www.abc.net.au/rural/news/content/201102/s3142796.htm
   Australia - copper and gold mining can create a leachate with hazardous levels of copper, manganese and zinc.
2. http://keeptheban.org/?p=678
   France - uranium mining - "accumulation of radioactive metals in sediments and plants of rivers, ponds, and lakes by contamination around former mine sites has also been found to have high enough contamination to be considered “radioactive waste”"

And a common example is acid mine drainage in which sulfide ore from underground turns into sulfuric acid upon reaching the ground surface (chemistry is involved). This can be quite serious as it can turn water very acidic - pH of 1 or less.

Example 2: Agriculture
Depending on the type of agriculture, you can find different pollutants in the soil or sediment. And these pollutants may subsequently leach into the adjacent water bodies. If the pollutant load in the soil/sediment is heavy, the leaching can occur over a long period of years. Short of dredging the entire load of sediment or bulldozing the whole lot of earth, the problem can only be treated symptomatically without eradicating it source. (See a potential case study in a previous post - How to get rid of your seemingly unstoppable pond algae at Sungei Buloh.)

If we are talking about crop land or plantations, there is a likelihood of pesticides and fertiliser residues in the soil/sediment. On the other hand, animal farms will likely introduce animal waste (which is also a source of nutrients) into the soil/sediment. Nutrients/fertilisers are especially good at promoting eutrophication in water bodies while pesticides can be toxic to the ecology and us.

Most of you probably knows that Sungei Buloh used to be house prawn and fish farms in its mangroves before being converted into the wetland reserve we know together. However, do you know that it used to house pig farms too? (Wetland forest of Sungei Buloh mangroves) Has all the pig waste been cleared from the area? If not, can this be a source of nutrients leaching from the soil/sediment into the current mangrove area and causing eutrophication?



Example 3: Estuaries
In simple terms, an estuary is the intersection between a river and the sea. It can be in the form of a swamp, bay, delta etc. Not only does it accumulate (depending on the tidal and hydrological conditions) stuff from the river (think about oil, pesticides, heavy metals), it can also receive pollutants from shipping (ballast, waste, cargo overboard), especially along a busy shipping channel or near a port.

The port and upstream factories may not be there anymore but the pollants remaint in the sediment, possibly for a long time of decades and slowly releasing its toxic load of heavy metals and persistent organics (including dioxins, PCBs (polychlorinated biphenyls), -cides (pesticides, insecticides, herbicides)). BUT if someone decides to dredge the sediment (perhaps to keep the channel deep for shipping), you may see the serious problem of a massive dosing of pollutants into the water. Morale of the story: don't disturb the sediment unless you intend to remove the whole chunk as a long term solution.

Incidentally, heavy metals or persistent organics can show up in bottom feeders such as shellfish (mussels, clams etc.). They accumulate the substances as they wade through the sediments for food. Of course, what this means is they are potential bioindicators - indicating the health of the environment without doing a chemical analysis first.

The other more serious implication is if the locals feed on these bottom feeders, they may very well be intoxicating themselves.

Figure: 1969 topo map of the area around Ngee Ann Stream. Notice that the old railway track splits into 2 lines near the Bukit Timah station. Old maps are a good source of information on the geographical history of the area. Another source is old aerial photographs.

Figure: Google Earth view of the same Ngee Ann Stream (imagery data 2009, 2010). Some roads and waterways remain after all these years.

Figure: Photograph from The Straits Times, depicting the floods in 1978 and men rescuing their pigs. More importantly, it tells you that Woodlands, Braddell Road, Potong Pasir to Changi used to be a "farm belt". Such old news are another source of information.

Figure: Quarry lake on Pulau Ubin. Disused after the granite quarry has closed. How does such a mining activity affect the water quality?

Water quality monitoring workshop for CUGE

I had the opportunity to conduct an inaugural water quality monitoring (WQM) workshop for CUGE (Centre for urban greenery and ecology). The participants were mostly Nparks staff. Before this, I had only worked with MOE teachers and students in my WQM courses.


It was indeed an eye opener. With their outdoor experience, my field trip became a non-issue. No complaints about the mozzies, the mud or the weather.

In fact, I dare say this field trip to Ngee Ann Stream was my most challenging. A huge tree has fallen over the path I normally took my participants. There was no clear path through it or around it. Fortunately, a hardy participant (L) came forward to blaze a trail through the fallen tree while I was wondering whether the rest were able to handle such bashing through. Reminding myself these were Nparks staff, everyone came through without a scratch despite the big ants scrambling all over the branches in protest of our intrusion. A few other “garang” types helped to clear the trail as L and I took the lead in our trailblazing.

Because of the wet weather earlier in the day, the canal was flooded. Usually a convenient way to cover ground, the canal became out of bounds. Since these guys and ladies were as good as I thought they were, I decided to do another round of bashing through a patch of tall grasses. Since these were only grasses (not trees or shrubs), I used my handy walking stick to sweep the blockage aside. Problem solved.

Though most of the participants have no chemistry background, they were thrilled with trying out the water testing kits back in our classroom. Designed for field work and hence simple to operate, most participants took an instant familiarity with the kits’ usage. In fact, they were more than enthusiastic to stay after 5p.m. to finish their water testing with the kits. It is always a pleasure to observe students with a passion to learn and experiment.

Figure: My favourite monitoring station along Ngee Ann Stream. A good shady spot for the participants to rest after the "gruelling" hike through tall grasses and steep slopes. Notice the tall grasses in middle - we had to bash through those after this station.

Figure: This canal is normally dry with only a small flow in the centre. On this day, an earlier rain has made the canal impassable. Even the participant has to collect a water sample on the steps. Not for school students.

Figure: Using water testing kits back in the classroom

Figure: Participants putting up their water quality data for all to see and compare.

Figure: Bug hunting and identification at Chinese Garden

Figure: We had the rare chance of checking out what Chinese Garden has implemented its admirable efforts to go green. This is a phytoremediation project to treat and reuse grey water from a toilet's sinks.


Update: Here is the link for a write-up of the workshop on CUGE' website
http://www.cuge.com.sg/October-2011 > 04 Oct 2011 - A Fun and Enriching Hands-on Experience Sampling and Testing Water

Outdoors classroom - Ngee Ann Stream

It is good to be back at Ngee Ann Stream where my water quality monitoring (WQM) workshop first started. Since then, I have brought groups on field trips to many other locales but none as charming as Ngee Ann Stream - so close to civilisation yet retaining the rustic and rural character of a lost world unknown to most Singaporeans. Despite losing some of its charm to development, I have never found another field location quite like it - a combination of different freshwater habitats, chest high Buffalo Grass to bash through, water seeping in through your shoes from the soggy soils, balancing yourself on narrow ledges, climbing down algae infested steps which are really part of a drain... the list goes on. (In KCK's list, Binjai Stream is in a close fight with Ngee Ann Stream for the most interesting waterway in Singapore but Binjai is more back to nature whereas Ngee Ann is more back to kampung so their charms are rather dichotomous.)

This time round, I have the pleasure of bringing students from River Valley High to my favourite outdoors classroom. The highlight of the trip must be the sudden heavy downpour near the end, accompanied by thunderous light show, courtesy of Mother Nature. Before this, many days have passed without rain - not a good sign as this means rain and thunderstorms become more probable with each passing day. (I know, this sounds like pseudoscience but it really works!)

Being in a canal when a big storm comes is a downright lousy place to be in - open terrain with no safe shelter and subject to flash floods which is such a trendy topic in Singapore nowadays. Being young (in age, if not, at heart) and energetic, we scurried back to the safe and dry confines of our transport in one piece. In case anyone thinks that such weather makes field trips a big no-no, nothing could be more wrong. We are living in Singapore, a country in the tropics - heavy rainfall is normal, thunderstorms are normal while shivering in an air-conditioned room all day is NOT normal nor healthy. We should not be baby-proofing nature (phrase is taken from Ice Age 3) for our youth. Given our current rate of development, I hope I won't ever see Singapore entombed in a climate controlled (aka air-conditioned) dome with nature only found in manicured parks and the only waterways are covered or canalised ones.

Ok, rant mode off... here are some pics for sharing.

Figure: Our field trip itinerary includes crossing the currently operational railway track. I always wonder what would happen to this beautiful patch of railway land when it is returned to Singapore. Will Ngee Ann Stream be further developed?

Figure: WQM in the canal. Most people don't get to climb into these canals throughout their lives.

Figure: In my opinion, the best photo of the day. Heavy downpour, wet staff and students, umbrellas out if available, a sense of urgency to scramble out from the canal - something real-life, capturing the moment and not posed

Figure: Posed photo - using a colour comparator to measure the ammonia content in the water back in the indoors classroom



A quick update for the past months

I would like to convince myself (and you) that my packed work schedule has prevented me from posting anything since the end of May. I know it is a shame but I am also sure that inertia has played a large part - not having posted for so long propagates the said behaviour :-)

In part to prove that I am really "busy" and to update you on the past activities, here is a summary of my "work".

June - July
Conducted "Freshwater quality and biodiversity" course for Crescent Girls, Henderson Sec Sch, Clementi Woods SS, Queensway SS. It was back to a tributary (sort of a naturalised drain) of Sg Ulu Pandan for more water quality testing and bug hunting.

Figure: The group hunt (for bugs)

Figure: Don't forget the water quality parameters

Figure: Sorting out the spoils of the hunt

Figure: A rare find - freshwater eel - too small for unagi though

Figure: The common Dragonfly nymphs though perhaps not so commonly seen by the students

Conducted a round of 6-day intensive AEM (advanced elective module) "Water quality and pollution".

Figure: On first sight, nothing wrong with the scene. But if you look closely enough, lots of people are looking down on their pants and shoes. This is what happens when you venture out in the wilderness in the rain and through knee high vegetation. All manner of creepy-crawlies are out their homes, latching on to the hapless passer-by (i.e. us).

Figure: Part of Ngee Ann Stream. Looks like another canal except that this used to be a natural stream with thick secondary forest on both edges. See next figure.

Figure: The same part of Ngee Ann Stream as the figure above but a year back. Note the vegetation stretching right to the edge of the secondary forest stream

Figure: An unusual find - a catfish struggling against the current in the "canalised" Ngee Ann Stream. Why was it doing so? I have no idea. Perhaps it should have just flowed along with the tide of change as what the rest of the stream did when it gave way to "development".

Figure: Due to the earlier heavy rain (what else is new in Singapore?), the whole canal was flooded, preventing the students from sampling the water (too dangerous).

Figure: The same part of the canal as the figure above but in drier times and more than a year back.

Figure: I simply can't resist putting in this routine group photo. Must show that the participants are in good spirits, right?

Singapore International Water Festival (27 Jun 2010)

Once again, I was roped in to organise the event "Amazing Greenviron Challenge" - an environmental quiz of sorts with indoor and outdoor components at the Marina Barrage. Weather was terrible in the morning so the outdoor part has to be moved indoors. (Right, rain was indeed heavy in June, giving rise to the shocking floods in downtown Singapore.)

Figure: Only 1 photo to show you here - the super group photo with organisers, student helpers and participants.

(Are we not done with the summary yet??? Afraid not... Did I mention that I had a tight schedule then?)

Water Quality Monitoring (WQM) (19 Jun 2010)

Amidst the tight schedule, I managed to sneak in a round of WQM with Team Seagrass at Chek Jawa.

Figure: On this rare sunny June morning, my students prepared their equipment for WQM.

To top it off, I attended the 4-day Wilderness Medical First Responder (WMFR) Course by OBS (Outward Bound Singapore) on Pulau Ubin. More on this in a later post.

Figure: WMFR participants and our dummies

WQM at Pasir Ris

Ah yes, the problematic kid on the block with regards to water quality - Pasir Ris Beach. (The latest advisory on its "fair" water quality is found here.) We checked out this notorious locale on this rainy July morning. Perhaps unknown to most people, this stretch of sand hosts 2 significant patches of seagrasses even though they are not monitored by Team Seagrass. (Some of the Team's members do however check out the seagrasses here in their own capacity.) And since there are seagrasses here, my team will of course be interested in the WQ.

Figure: 1 patch of seagrasses near Sg Loyang

Figure: The 2nd patch of seagrasses near Sg Tampines. I was told that there is a smaller patch further west near the end of Pasir Ris Park. We did not check this one out though.

Back to Ngee Ann Stream with Fairfield Methodist School (15 Mar 10)

This particular field trip for my advanced elective module (AEM), water quality and pollution, was reported in the Straits Times (25 Mar 10).

I have decided to post some exclusive footage not captured in the news article. (Actually, these are just routine photos I take every time I head to the field.) In addition, I have included a Google Earth file compiling all the water quality data gathered by the students on that hot and sunny morning. The students were given hands-on practice on the use of Google Earth as a means of documenting water quality data.

Figure: The 4 sampling stations displayed in Google Earth. Notice the ugly patch of cleared land. More land has since been cleared as Google Earth satellite photos are back dated. See previous post.

Aside to FMSS students in selected groups: Please use the compiled data in the Google Earth file to prepare for your case study presentation.

Figure: Group work at sampling station 2.

• The humble umbrella is immensely useful for field work as it can shield one from the rain and sun. (Try recording your data on a rain soaked piece of paper and you will know what I mean.)
• The other point to note is the highly turbid (muddy) water caused by sediments being washed down the canal from the nearby construction site. In fact, the turbidity exceeds 1000NTU which is the measurement limit of our turbidimeter (you may check the data here). This has never been observed before in this stretch of water.

Figure: Construction site - clearing of the secondary forest in progress. Note the open ground of easily eroded soil

Figure: Moving on from station 2. The canal floor was still wet from the drizzle earlier in the morning.

Figure: The customary group photo at "Graffiti Bridge" (sampling station 3). Many happy faces despite the "bedraggled" appearance

Water quality in Bukit Timah Nature Reserve (BTNR) - part 2

Here is an update to my water quality monitoring (WQM) work in BTNR under page 12 of Nature News (Mar - Apr issue).

Figure: Map of BTNR with the locations of the 3 sampling stations - streams cutting across Jungle Fall Path, Seraya Loop, Rock Path

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.

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

Singapore Bug List

In response to queries from some readers regarding the types of bugs (macroinvertebrates) found in Singapore's fresh waters, I have compiled a quick list of the bugs I have encountered.

I have broadly classified our fresh water bodies into 3 types:

1. Ponds

Figure: A very stagnant pond next to Sungei Ulu Pandan

Figure: Turbid pond in the forest near Dover MRT station. (Sorry folks, if you intend to visit this one, forget it as the whole area is now under construction.)






Bugs present:

1. Leeches! And big ones too! These are whoppers compared to the tiny terrestrial ones commonly encountered in Malaysian jungles. I was told that they are Buffalo Leeches (unverified).
   
   There are also tiny ones (fingernail sized).
2. Dragonfly
3. Damselfly
4. Water stick insect
5. Mayfly
6. Pond skater
7. Chironomid ("Bloodworm")
8. Sludge worm
9. Beetle

NO Caddisfly!

Unsurprisingly, when the dissolved oxygen (DO) level drops low (say below 2-3mg/L), the ponds become infested with leeches which crowd out the friendly bugs e.g. Mayflies.

2. Streams

Figure: Ngee Ann Stream riffles surrounded by secondary forest then. If you want to visit this wonderful stream, do it soon because the adjacent land is cleared and under construction (yawn, what else is new?). Who knows when the stream will be paved over to make way for yet another condominium?

Figure: Binjai Stream. A good old clear stream PROVIDED rains do not wash sediments into it.

Figure: Tributary into Sungei Pandan. This is a good example of a canal that looks like a natural stream.

Bugs present:

1. Snail (lots of them in the tributary leading to Sg Pandan)
2. Collembola
3. Dragonfly
4. Damselfly
5. Eel
6. Shrimp
7. Crab (Binjai Stream. Yes, this stream is clean and natural enough to find crabs.)

NO Mayfly! NO Caddisfly!

3. Freshwater reservoir

Figure: MacRitchie Reservoir. Fully exposed to the sky.

Bugs present:

1. 
   
   Mayfly
2. 
   
   Dragonfly
3. 
   
   Damselfly
4. 
   
   Chironomid
5. 
   
   Shrimp
6. 
   
   Snail
7. 
   
   Lentil Shrimp
8. 
   
   Caddisfly

NO Leech!

Disclaimer: Haha, this is definitely not a complete list. All the above bugs are based on my experience in those waters.

Strangely, NO Plecoptera (Stonefly) and Megaloptera have been found so far in Singapore waters! These 2 orderse are supposed to be really common in other countries e.g. USA, UK.

Acknowledgement: Many thanks to Esther for introducing me to the world of water bugs! I am still learning lots more from her.

One last comment:

Forget about finding bugs in artificial fish ponds with little or no natural substrate - e.g. below