AEM: Water quality and pollution (Mar - Apr 10)

It always feel good to get into teaching water quality monitoring (WQM) to students. No doubt, you can argue round and round about the benefits to the environment, the next generation, the world etc. but ultimately, the teacher/instructor has to be passionate about what he teaches. If not, all the other reasons do not matter.

Here is the latest batch from Fairfield Methodist School (Secondary).

Figure: Introduction to WQM by having a "field trip" to the nearby fish pond. Notice the student in the foreground wearing slippers. He became the first "casualty" when he slipped into the water. Yes, such things happen, even in a controlled environment like a fish pond.

Figure: Basic data collected on the fish pond. They seem to indicate that the fishes are having a good time in the well maintained pond.

Myth or miracle? - Using 1-cent coins to destroy mosquito eggs

The following email about using the Singapore 1-cent coin (another version uses the Malaysian equivalent) to stop mosquito breeding has been circulating around. At first glance, this appears unrelated to water quality but read on... and find out another aspect of water quality and macroinvertebrates (bugs) that we seldom think about. (The common theme is about how clean water is indicated by a healthy bug community while polluted water is often dominated by the "uglies" such as leeches, tubifex worms.)

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Subject: How to prevent mosquitoes lay eggs, cheapest way of preventing survival of mosquitoes.


We cannot stop mosquitoes laying eggs at any stagnant water in drains/ponds or water collected in waste pails, tanks, tins, used tyres etc. etc. Of course if you have fish inside the tanks/containers then there should be no problem.


Do you know that there is a very simple and very economical way to destroy the mosquitoes' eggs and not let them hatch into larvae. Very very simple, just put in few 1 cent copper coins into the tanks/containers then it will solve all your problems.. Because in accordance to Japanese Research Scientists, they found the mosquitoes eggs will be destroyed by a kind of mineral discharge from the copper.


DON'T BELIEVE, Try it by yourself and even the small snails also will not visit the containers (with copper coins) collected with stagnant water. You will observe the water collected in the containers will be very clean and clear.
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Should you save up your 1-cent coins to keep the mozzies away? (By the way, production of 1-cent coins has been discontinued some years back due to inflation.) Here's my take:

Certain heavy metals (e.g. copper, lead) have been known to be toxic to bugs and their larvae in water (selected ref: 1, 2). These heavy metals exert their toxicity when they are dissolved in water at concentrations as low as below 1ppm (part per million).


The Singapore 1-cent coin is made of zinc plated over by copper according to the Singapore Mint. Solid copper is barely soluble in water but under certain conditions (e.g. acidity), significant amounts of the copper plating can dissolve into solution. With a sufficient concentration of dissolved copper in water, mosquito larvae (or eggs which are usually more vulnerable) can be killed.

Is the water then safe for drinking? It depends on the final concentration of dissolved copper. WHO (World Health Organisation) provided a maximum limit of 2ppm (2004 guideline) of copper in drinking water. But pouring the water into the sewers should not pose a problem.

Myth or miracle? Neither, it is science. No harm trying but I wouldn't count on this method as my only defence against mosquito breeding.

You can also read my interview on this topic in Lianhe Wanbao (4 Mar 10).

Dear, we have run out of water from the tap. Can you head to the nearest supermarket and loot some? (Earthquake in Chile)

Different country but same story and ramifications.

Chile was hit by a magnitude 8.8 earthquake on 27 Feb 10, killing at least 700 people by last count. As always, the quest for survival has only started for the survivors. Public utilities like water, gas, electricity and telephone are down. Police presence is barely felt but sorely needed as some parts of the country turn into a looters' paradise.

Imagine a densely populated city like Concepcion (the hardest hit major city) and take away all public utilities. You now have a recipe for social chaos. People become desperate when no water comes out of the tap, the food stalls and supermarkets are closed, no lights to reassure the soul at night, transportation is dysfunctional.... When children get cranky from hunger and thirst, parents are invariably driven nuts.

Cops also face the same challenges and need to take care of their families. It will be lucky if half the police force turns up for work.

Not surprisingly, looting starts and spreads. And the number one items looters look for - water (bottled, packaged, canned), food (bread is a favourite), lighting (candles, torches) and fuel.

Remember, electricity is so ubiquitous in our city lives that if it fails, lots of other systems fail (aka systems built upon other systems in Matrix Reloaded). Even if you want to be law abiding and pay for your groceries, you probably can't do so as the ATMs, NETS (or its equivalent in Chile), cash card and credit card machines are down.

Similarly, even if petrol stations are willing to risk opening for business, their pumps can't work without electricity so your vehicle is only left with whatever gasoline remains in the tank. Therefore, we see footage of looters siphoning fuel from underground storage tanks at petrol kiosks, probably using manual or portable electric pumps.

Throw some opportunistic looters going after electronics and non-essential items in the mix and you have an anarchy brewing.

By the way, the above events are happening just on the second day after the quake. Who knows how ugly the situation will degenerate if utilities remain down for a week, 2 weeks?

One other thing - don't count on your hand phones working either. The base stations or switches may be hit by the earthquake itself or they may have shut down due to the lack of power. Heck, even your own mobile may go "low batt" without a power supply to recharge. (Or are you one of the lucky few to have a crank operated mobile charger? Hint, hint. ) In Chile, the government actually sets up a generator in a public area for people to charge their mobiles. Yes, communications is right at the top of the list, next to water, food and lighting. Another concern is even if the mobile network is all and well, you can expect the network to be jammed in the initial hours after a catastrophe. (This happened right after the Sep 11 terrorist attacks.)

Folks, do keep some supplies at home - water especially, food, candles (torches, batteries), first aid items. If you consume soft drinks, why not reuse the PET bottles to store water instead of dumping them? More environmentally friendly too. If you have empty Lock-and-lock containers lying around, fill them with water. Water is not just for drinking, you still need to wash, bathe, cook and even clear your waste in the W.C.

See my previous post on Haiti for a related discussion.