Environmental Pollution

Singapore’s online newspaper TODAY, produced by MediaCorp, carries an article today (14 September) that seeks to clarify confusion over which air quality index we should refer to when deciding whether to venture outside now that the haze is back. You can read the article here. I am not sure that I am any less confused having read the article.

I prefer to use a scale that matches air quality (and in particular the concentrations of small particles, or PM2.5) to the equivalent numbers of passively smoked cigarettes, published by van der Zee et al in 2016 in the journal Environmental Pollution. This scale assumes that there is no safe level of PM2.5.

Van der Zee is based in the Public Health Service of Amsterdam, Netherlands. He and co-workers determined that every 10 ug/m3 increment in PM2.5 corresponded to on average between about four to seven, passively smoked cigarettes per day. With PM2.5 concentrations in Singapore approaching 100 ug/m3 that equates to at least 40 passively smoked cigarettes. Let’s not forget that smoking in public places was banned because of the health risks of passive smoking.

Several news agencies, including the BBC, are currently reporting on the electricity power generation industry’s “dirty secret” ~ leaks of Sulphur hexafluoride, or SF6. SF6, a synthetic combination of one sulfur atom and six fluorine atoms, is commonly known as “deep voice” gas because of the effect that it has on the human voice. Its other properties are that it is inert, colourless, odourless, a lot heavier than air and does not conduct electricity. Because of the latter, it is used in the electricity power generation industry as an insulating medium to prevent electrical short circuits that can lead to fires and power outages.

Why is SF6 in the news at present? Well, it seems that as the world moves to smaller power generation plants – e.g. those associated with green (renewable) energy sources, the number of connections to the power grid increases. With that increase comes an increase in the number of locations where short circuits are possible, and hence a greater need for SF6. Why is that a problem? Well possibly as much as 15% of the SF6 used to prevent accidents in the power generation industry leaks out into the environment, where it is an extremely potent greenhouse gas. Just one kg of SF6 is equivalent to about 23,500 kg of CO2, and because SF6 is synthetic and inert it degrades very slowly, so emissions today are likely to be around for hundreds if not thousands of years.

Recently published research in the journal Energies (see journal article linked to this blog post) highlights the increased use of SF6 in the UK’s power generation industry, and the increased leaks as a result. Replicated across Europe, a similar rate of leaks equates to around 6.73 million tonnes of CO2 per year, or the emissions from 1.3 million extra cars on the road for a year. The use of SF6 is regulated in developed countries, but developing countries are under no pressure to regulate its use.

The generation of energy from renewable sources is an obvious improvement on relying on fossil and nuclear sources of power, but it also has its problems. Clearly the answer lies in finding ways of using renewable energy that are less wasteful of resources such as SF6 (how much energy does the synthesis of SF6 use?) in combination with reductions in the total amount of energy we use to live our daily lives (and therefore has to be generated). Another argument for economic degrowth as opposed to the current mindless fixation with ever-increasing, potentially planet-trashing GDP?

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An item on the BBC website is today reporting on high concentrations of pollutants found in the skin and body fat (blubber) of bottlenosed dolphins in the English Channel. You can access the report here. The BBC report is based on an article that has only very recently been published in the journal Scientific Reports. The full article jn Scientific Reports is attached to this blog.

The pollutants include the heavy metal mercury and Polychlorinated biphenyls (PCBs), persistent organic pollutants (POPs) posing a serious environmental threat to wildlife and humans. PCBs were banned in many developed countries in the 1970s and 1980s (i.e.40-50 years ago), but they have persisted in the environment since the ban. You can learn more about PCBs here. Other chemicals were also found, including the residues of pesticides, in what the authors of the article refer to as a “cocktail of pollutants”.

Unfortunately it is not uncommon to find high levels of harmful pollutants in marine life, including in the fish that we eat. One killer whale found dead off the coast of Scotland was discovered to have “shockingly high” levels of PCBs in its body fat, while the health benefits of consuming fish can be undermined by high concentrations of heavy metals, such as lead, cadmium, arsenic and mercury, in the body fat of those same fish.

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This coming Monday we will talk about ocean pollution. A current focus on plastic pollution in our oceans has – to some extent – caused us to forget about another major threat to our oceans, that of acidification.

Ocean absorb about 30% of carbon dioxide (CO2) that enters the atmosphere. As emissions of CO2 to the atmosphere increase, then the amount taken up by oceans (the size of the ocean CO2 sink, in other words) also increases. Oceans are therefore an important sink for anthropogenic (i.e. human) CO2 emissions. But what happens to that additional CO2 in oceans? Basically CO2 dissolves in sea water forming carbonic acid (H2CO3). Increased concentrations of carbonic acid reduce the pH (increase the acidity) of seawater. This increased acidity impacts other compounds and ecological processes, including the availability of carbonate ions (the building block for calcareous marine life, such as corals). For example the exoskeletons of corals are largely formed from aragonite, a form of calcium carbonate (CaCO3). We have know for some time that consumption of carbonate ions starves calcareous marine life of the material they need to grow (and, e.g., to keep pace with rising sea level) and to protect themselves from potential predators. Moreover the increased acidity can result in the dissolving of existing calcareous shells. So calcareous marine life faces two problems as a result of acidification – a shortage of carbonate to produce new shell material, and a weakening of their existing shells as a result of the increased acidity (reduced pH) of ocean water. Marine life faces other problems of course, including over exploitation,oceanic warming and pollution …. And not just pollution by plastic,  pollution by toxins such as heavy metals is also becoming an issue, as we will discuss in this coming week’s tutorials!

Early last year (2018) the Woods Hole Oceanographic Institution (WHOI), US, summarised the threat of ocean acidification on corals, focusing in particular on the link between ocean acifidication and the weakening of coral skeletons. Click here to view the article. Note that researchers at WHOI found that coral growth was much more complex than previously had been thought, and this complexity perhaps explains why some corals in some parts of the world are more vulnerable to ocean acidification than others. Basically what the researchers found was that the polyps – the tiny animals that form coral – were still able to produce aragonite at lower pH, but the aragonite was thinner, or weaker, because of an abundance of carbonic acid (HCO₃^–) ions relative to carbonate (CO₃^2-) ions in seawater. This results in corals located in exposed areas, where wave strength is greater, for example, being more vulnerable to damage than those corals in less exposed locations, even though the pH of the seawater might be similar.

Below you can watch an excellent, relatively short, documentary on the subject on ocean acidification, produced by the BBC and released in 2018. Australia gets a bit of a hammering in the documentary. The Great Barrier Reef is one of the world’s great coral ecosystems and is off the northeastern coast of Australia. Australia is one of the world’s largest exporters of CO2 emitting coal – in fact coal is Australia’s most valuable export ….

https://www.youtube.com/watch?v=Bxcq9QemIP0

Generally we assume that pollution is harmful to human health, and that the level of harm increases linearly with the level of pollution. Indeed, that is the assumption that many regulatory agencies adopt when setting pollution standards. For example, most air quality indices assume increasing harm as air quality deteriorates. But humans – indeed life on Earth more generally – have evolved under at times harsh conditions, while some stresses on our bodies (e.g. frequent and regular exercise) are commonly thought to be a good thing. Furthermore, we are sometimes told that drinking alcohol – a toxin – in moderation can have life-enhancing benefits. These apparent inconsistencies in the assumed relationship between (pollutant) dose – (human health) response are encapsulated in the phenomenon known as Hormesis, or the process in which low levels of toxins appear to have beneficial biological effects.

The attached study by Heinz et al. (2010), published in the journal Environmental Science and Technology, is said to provide evidence of hormesis ~ in the form of enhanced fecundity among breeding pairs of mallard ducks (Anas platyrhynchos) linked to very low concentrations of methylmercury in their diet. At higher concentrations methylmercury is extremely harmful, but at low concentrations in this example appeared to have increased birth and survival rates of ducklings.

Hormesis is controversial, and no doubt more work needs to be done on the topic, but some have suggested that its widespread adoption might allow a weakening of pollution regulations (which might then make pollution regulations cheaper and easier to implement).

Of course, we’d be better off not polluting at all, even it pollution was not harmful ….

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I had an interesting meeting earlier today. I was invited to meet with Zhaotan Xiao, the President of the Singapore-based Asia-Pacific office of RWDC Industries. RWDC Industries have been in the news in Singapore of late through their development of a polyhydroxyalkanoates (PHA)-based drinking straw, which is being suggested as a commercially-viable alternative to conventional plastic straws. PHAs are polyesters, a type of hydrocarbon, that are produced by several types of microorganisms, such as the bacterium Cupriavidus necator, through fermentation of vegetable-derived oils and sugars. They can be mixed with other compounds (e.g. calcium carbonate) to form single-use plastic-like substances that unlike plastics from petrochemicals are biodegradable over relatively short timescales. In fact at today’s meeting we were told that a drinking straw made from PHA would completely biodegrade once released to the environment in as few as 12 weeks. Aside from straws, Zhaotan also showed us PHA-derived, bioplastic-backed paper ~ the kind of material that in its petrochemical-derived form is extensively used, including in the manufacture of disposable coffee cups. According to Zhaotan the PHA-derived bioplastic commodities we were shown have the potential to be produced at scale and at a cost that makes them commercially viable.

All sounds great. Should we be wowed? Has RWDC found the answer to the global problem of single-use plastic pollution? Even if everyday disposable commodities can be made at low cost from biodegradable plastic, is that really the answer? Waste is still waste, surely, even if it does biodegrade? What about the energy that has been used to produce a commodity that is simply thrown away after a single use, or at best a relatively few uses? What about all the embedded pollution in producing single use items, especially given that all plastic items, even those made from biodegradable bioplastics, contain additives, to make the plastic more malleable, more heat-resistant, less combustible etc – and those additives (e.g. Biosphenol A, or BPA) may be even more harmful than the plastic?

The development and use of PHA is an example of Green Chemistry in operation. No doubt Green Chemistry, or the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances, has some of the answers to questions regarding environmental pollution. Green Chemistry – or at least the promise of finding environmentally friendly ways of maintaining or even allowing an increase in consumerism – runs the risk of moral hazard, however. What if none of these proposed solutions actually work, while the prospect of them actually working has persuaded us that we don’t need to change our behaviour to make fewer demands on our environment? What happens then?

PHA is not a new discovery, as Zhaotan was happy to acknowledge at today’s meeting. I hope that RWDC goes on to fulfill all its early promise. If it doesn’t, however, it will not be the first producer of bioplastics to run into trouble because it promised more than it could deliver ….. Only a couple of months ago, shares were suspended in the Italy-based Bio-On company, which produces “environmentally-friendly bioplastics” including a PHA-based replacement for plastic microbeads used in cosmetics etc, having been accused on the Reuters website of being “a massive bubble based on flawed technology and fictitious sales”! Hopefully bioplastics will provide a real alternative to petrochemical-based plastics, but don’t let that distract us from the real source of the global plastic pollution problem ~ our extremely wasteful use of the world’s resources, however quickly the commodities they are used to produce eventually degrade.

A question that has been troubling me and a group of graduate research students working with me for some time is how much of the air pollution that we face in Singapore originates from outside the country? In other words, just how big a problem is transboundary air pollution here in Singapore? We’re all familiar with periodic haze events, and with the idea that the haze originates somewhere else (generally biomass burning in neighbouring countries), but what about other components of air quality? How much non-haze related air pollution from neighbouring countries reaches us here in Singapore, bearing in mind the rapid rate of industrialisation and urbanisation that has taken place not very far away in Johor and in Riau Province, the relatively lax environmental regulations in those places, the atmospheric residence time of some pollutants, including heavy metals in their gaseous phase, and the fact that while the NEA here in Singapore effectively regulates local potential sources it can do very little about sources that are located outside the country? Regulating the latter requires some form of international agreement ….

In the attached paper Letisha Fong who recently obtained her MSoc Sci degree in Geography at NUS provides what we think is evidence of increased deposition of transboundary atmospheric pollution in Singapore over the last 20 years or so, possibly linked to urbanisation and industrialisation in neighbouring parts of the region. The article attached is “in press” and is expected to appear in print later this year. Letisha used an interesting (almost novel in this region) source of information to trace changing levels of atmospheric pollution depositions over the last 100 years or so (i.e. far longer than the available instrumental record of pollution in Singapore). We will cover the approach that Letisha adoped later in the GE3246 module, along with other approaches that are used to determine and monitor air and water quality.

Hopefully I will be able to post another couple of papers that try to quantify changes in levels of depositions of transboundary atmospheric pollution in Singapore in the near future (these papers are currently under review with publishers). The evidence presented in these two papers is perhaps more convincing (it is, for example, backed up by a detailed National Emissions Inventory for Singapore) and is used to argue that we need much better international cooperation when it comes to the management of pollution in Southeast Asia ~ it would seem to be common sense that there is minimum benefit from simply tightly regulating local (i.e. within Singapore) pollution sources if harmful pollutants can simply blow over from neighbouring countries where environmental regulations are either non-existent or far less strictly enforced. In fact, under such conditions Singapore’s regulations could actually end up being economically detrimental to the country, with little in the way of real benefit to environmental quality, as polluting industries relocate to neighbouring countries creating a pollution haven effect.

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Geography majors and Biology and Environment (Environmental Geography) students will have the opportunity during the recess week of Sem 1, Academic Year 2020-2021 to camp at several locations in the Kenyan part of the Great Rift Valley, eastern Africa.

Plastic pollution has become a major problem in Kenya, as in many African countries, and indeed many parts of the world, as existing waste management facilities struggle to keep pace with the changing nature and increased volumes of waste in general and plastic waste in particular. In response, the Government in Kenya introduced a complete ban on the use of plastic bags in the country a year or so ago. Anyone found violating the law faces a fine of up to almost US$ 40,000 and a custodial sentence of up to four years!

For a report on the situation in Kenya a year after the ban, see the opinion piece here.

Other countries in Africa have introduced bans on plastic bags, others have tried to influence behaviour through the implementation of taxes on plastics. No country anywhere in the world has introduced anything so extreme as in Kenya.  Some countries have adopted a different approach, viewing plastic waste as an economic opportunity. See here for an example from Nigeria – Nigeria’s Plastic Bag Fashionistas! As students who visit Kenya will no doubt discover for themselves, there are few places on Earth as innovative – in the truest sense of the word – as Africa.

Just want to post a link to the documentary “Luces en el Sacrificio” (“Lights in the Sacrifice”). The documentary focuses on an industrial zone in coastal Chile, South America – centred upon the towns of Puchuncaví and  . The industrial zone is associated with high levels of industrial pollution that have had and are having devastating effects on the local population. Some of you will have heard about Minamata in Japan, where mercury pollution, and methyl mercury in particular, during the 1950s and 1960s led to severe health impacts on and large numbers of premature deaths among the local population (Minamata disease), and eventually to the Miamata Convention limiting the environmental release of mercury.

Puchuncaví and Quintero are a modern example of Miamata, where some people are still allowed to put profit ahead of the health of other people and of our environment more generally. In doing so they have created a “zone of sacrifice”, but also brought together a community in their opposition to the behaviour of the industries concerned (the “lights in the sacrifice”).

The documentary was made by a Chilean friend of mine. The company she works for is a not-for-profit organisation. Please let me have your feedback if you have chance to watch the documentary so that I can let my friend know.

The documentary is 57 mins long and, although in Spanish, is sub-titled throughout in English.