Showing posts with label pollution. Show all posts
Showing posts with label pollution. Show all posts

Wednesday, April 4, 2018

Life in Plastic Ain’t so Fantastic

Guest post by Louis Vassos, MEnvSci Candidate in the Professional Masters of Environmental Science program at the University of Toronto-Scarborough

Much like the Buggles’ 1980 debut album, our material preferences are well within the age of plastic. Thanks to its light weight, durability, inertness, and low manufacturing costs, our use of plastics has increased dramatically since the mid-20th century. From bottles and toys to car parts and electronics, there is seemingly no application beyond its reach. Despite its uses and benefits, it has come under increasing scrutiny by environmentalists in recent years. In this regard, we tend to think of larger-scale and more visible environmental impacts, such as accumulation in landfills and petrochemical use in manufacturing. There has also been a significant amount of research on plastic in marine environments, usually focused on larger debris known as macroplastics. Over the past decade, however, there has been increasing concern about a new type of plastic debris in our oceans. Though its presence was first highlighted in the 1970s, we are only just beginning to realize the impact of fragments known as microplastics. As their name would suggest, they are small pieces of plastic, typically measuring less than 5mm in diameter and sorted into two distinct classifications.

Primary microplastics are manufactured to be microscopically sized and are typically used in air blasting as a paint and rust remover, as well as in personal care products as an exfoliating scrubber. This latter use has risen sharply in cosmetics and facial cleansers since the 1980s, with plastic “microbeads” replacing natural materials such as pumice and ground almonds. Regardless of application they usually enter water bodies through drainage systems, and are easily able to pass through filtration systems at sewage treatment plants due to their small size.

Microbeads in toothpaste. Retrieved from:

Secondary microplastics arise from the breakdown of larger pieces of plastic debris on both land and in water. Larger debris will typically enter marine ecosystems directly or indirectly through careless waste disposal, often being transported through river systems. Sources of transfer include coastal tourism, extreme weather events, fishing, other marine industries, and accidental spillage during transportation. Over time, a culmination of processes such as exposure to UV radiation can reduce the debris’ structural integrity, causing brittleness, cracking, and yellowing. This in turn can lead to fragmentation through abrasion and waves, and fragments will gradually become smaller over time before reaching microplastic size (Cole et al, 2011).

As Eriksen et al (2014) have estimated, there is a minimum of 5.25 trillion plastic particles weighing 268,940 tons in the world’s oceans. Microplastics account for 92.4% of this mass, and their reach has been substantial. Because of their buoyancy and durability, they have the ability to travel long distances without degrading for years. Denser plastics (such as PVC) will sink and have the potential to reach coastal sediment (Andray, 2011). Other marine microplastics will end up trapped in ocean current systems known as gyres, the most famous grouping of which is the “Great Pacific Garbage Patch” in the North Pacific Gyre. Despite what the name would suggest, it is not an island-like mass of floating debris, but is more akin to an extensive “soup” of debris difficult to see with the naked eye. At a density of 334,271 pieces/km2, microplastic mass in the area was found to be 6 times that of plankton (Moore et al, 2001). 
Potential microplastic transport pathways (From Wright et al, 2013)

Densities such as this increase potential microplastic ingestion by various marine organisms, especially filter feeders, plankton, and suspension feeders. These species may mistake debris for prey based on size or colour, or passively ingest them without being selective (Wright et al, 2013). In Farrell and Nelson’s (2013) study of mussel-eating crabs, they found that it is possible for microplastics to be transferred to individuals at a higher trophic level. The large surface area to volume ratio of microplastics makes them susceptible to water-borne pollutant contamination, and can cause toxic plastic additives such as BPA and PCB to leach into the water. This debris can also act as a dispersal vector for microbial communities, including potentially pathogenic species (Jiang et al, 2018). While the ingested debris can accumulate within individuals and be transferred up the food chain, the exact effects of this are not entirely known at this point in time (Avio et al, 2017). A recent study by Lei et al (2018), however, found that microplastics can cause oxidative stress and intestinal damage in zebrafish and nematodes, and that their toxicity is closely dependent on particle size.
Intestinal damage in zebrafish caused by exposure to 1.0 mg L-1 of different microplastic types and sizes. Photograph A shows control (top), survival (middle), and dead after exposure (bottom) zebrafish (From Jiang et al, 2018)
Fluorescent microspheres on a crab’s gill lamella transferred from ingesting mussels, each measuring 5 micrometres in diameter (From Farrell and Nelson, 2013)

          What does the future hold for microplastics? Because their effects on both marine life and humans is relatively unknown, it is important to try and prevent them from entering and accumulating within marine environments. Properly dispose of larger plastic items to prevent them from entering waterways and breaking down into secondary microplastics, and be conscious about the presence of primary microplastics in other products. Make informed decisions when buying cosmetics, and choose ones that use natural exfoliating materials. Microbead bans have already begun to be enacted in several countries, including the UK, US, Canada and New Zealand (Pfeifer, 2018). There is also the potential for future studies on topics such as the health effects of microplastic ingestion and leached additives, debris behavior within the water column, and new standardized techniques for detection and sampling (Cole et al, 2011). It is hard to say what will happen next, but the removal of these 5.25 trillion particles from our oceans will prove to be a very difficult challenge without the development of novel extraction methods.


Anadrady, A.L. 2011. Microplastics in the marine environment. Marine Pollution Bulletin 62:1596 – 1605
Avio, C.G., S. Gorbi, and F. Regoli. 2017. Plastics and microplastics in oceans: from emerging pollutants to emerged threat. Environmental Research 128: 2 – 11
Cole, M., P. Lindeque, C. Halsband, and T.S. Galloway. 2011. Microplastics as contaminants in the marine environment: a review. Marine Pollution Bulletin 62:2588 – 2597
Eriksen, M., L.C.M. Lebreton, H.S. Carson, M. Thiel, C.J. Moore, J.C. Borerro. F. Galgani, P.G. Ryan, and J. Reisser. 2014. Plastic pollution in the world’s oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PLOS One
Farrell, P., and K. Nelson. 2013. Trophic level transfer of microplastic: Mytilus edulis (L.) to Carcinus maenas (L.). Environmental Pollution 177:1 – 3
Jiang, P., S. Zhao, L. Zhu, and L. Daoji. 2018. Microplastic-associated bacterial assemblages in the intertidal zone of the Yangtze Estuary. Science of the Total Environment 624:48 – 54
Lei, L., S. Wu, S. Lu, M. Liu, Y. Song, Z. Fu, H Shi, K. Raley-Susman, and D. He. 2018. Microplastic particles cause intestinal damage and other adverse effects in zebrafish Danio rerio and nematode Caenorhabditis elegans. Science of the Total Environment 619:1 – 8
Moore, C.J., S.L. Moore, M.K. Leecaster, and S.B. Weisberg. 2001. A comparison of plastic and plankton in the North Pacific Central Gyre. Marine Pollution Bulletin 42:1297 – 1300
Pfeifer, H. 2018. The UK now has one of the world’s toughest microbead bans. CNN. Retrieved from:
Wright, S.L., R.C. Thompson, and T.S. Galloway. 2013. The physical impacts of microplastics on marine organisms: a review. Environmental Pollution 178:483 – 492

Wednesday, August 31, 2016

#EcoSummit2016: Conferences –the piñata of ideas.

One of the greatest benefits of attending conferences is that they represent learning opportunities. I don’t necessarily mean learning about new techniques or analyses, though you can undoubtedly find out about these at conferences, but rather conferences are opportunities to hear about new concepts, ideas and paradigms. In some ways conferences are like a piñata of ideas –they are chalk full of new ideas but you never know which you’ll pick up.

Ecosummit is not the typical conference I go to, it is much more diverse in topics of talks and disciplines of the attendees. This diversity –from policy makers, to social scientists, to ecologists, means that I am exposed to a plethora of new concepts. Here are a few nuggets that got me thinking:

  • Knowledge-values-rules decision making context. Policy decisions are made at the interface of scientific knowledge, human values (what is important to people –e.g., jobs), and rules (e.g., economic laws). This seems like a nice context to think about policy, though it is not clear about how we prioritize new knowledge or alter values.


  • Adaptation services. I work on ecosystem services (e.g., carbon storage, pollination support, water filtration, etc.), but I learned that ecosystems also provide adaptation services. These are aspects of ecosystems that will help human societies adapt to climate change (e.g., new products).

  • Trees and air pollution. The naive assumption most of us make about trees in urban areas are that they improve local air quality. However, I saw a couple of talks where this may not necessarily be the case. Some species in North American (red oak, sweet gum, etc.) release volatile organic compounds. Spruce plantations may not take up nitrogen oxides, and in fact might release it. Thus we need to be careful on how we sell the benefits of urban trees.

  • Transformative. This is a term I have certainly heard and used before, but in listening to a wide variety of talks, I realize it is used in different contexts to mean different things. I think it best to avoid this term.

  • a-disciplinary.  I heard a guy say in a talk that he was a-disciplinary and so was not bound to the dogmas and paradigms of any discipline (I already have a hard time wrapping my head around interdisciplinary, multidisciplinary, transdisciplinary, etc.). He then presented a new paradigm and a number of prescribed well-formulated tools used to move from idea, communication, to action. I think the irony was lost on him.

Wednesday, March 23, 2016

The evolutionary canary in the coal mine*

*note -this post originally appeared on the Applied Ecologist's blog

Like canaries in coal mines, species can provide important information about deteriorating environmental conditions. A whole sub-discipline of environmental biomonitoring has emerged to provide the necessary tools to evaluate biological responses to changes in environmental conditions. While historically biomonitoring focused on contaminant concentrations in sentinel species –such as heavy metals in clams; modern biomonitoring uses information across multiple biological levels of organisation, from tissues, to organism behaviour, to the abundances and distributions of species. Since it is impossible to assess every aspect of an ecosystem’s response to pollution, scientists and practitioners still need to make decisions about which elements of an ecosystem should be monitored.
A coal miner with a canary –the classic sentinel species (url for photo:

In freshwater systems, diatoms are often the preferred organisms for monitoring since they have high diversity and diatom communities are structured strongly by local environmental conditions. Because of their long use in biomonitoring, freshwater biologists have sensitivity and indicator values for thousands of diatom species. Thus, in principle, you should be able to sample diatom communities in lakes and rivers of interest, and then assess the water quality based on the presence and abundance of different diatom species. While such proxies should always be validated and interpreted carefully (Stephens et al. 2015), there is a long and successful history of using diatoms for environmental monitoring.
Image of diatoms from a scanning electron microscope. (By Kostas Tsobanoglou - Own work, CC BY-SA 4.0,
The difficulty in practice is to identify diatom species, which requires expert training and can be time consuming. A number of researchers have pursued proxies and surrogates, for example using life form (e.g., diatom shape) or higher taxonomic groupings, instead of identifying species (Wunsam, Cattaneo & Bourassa 2002). In a recent article in the Journal of Applied Ecology, Francois Keck and colleagues (Keck et al. 2016) take this one step further, by using diatom evolutionary relationships as the biomonitoring tool.

Keck et al. employ novel statistical methods to create clusters of species based on their evolutionary relatedness from a phylogenetic tree and species’ sensitivity to pollution and show that these clusters, when delineated by short to moderate phylogenetic distances, do a good job of replicating species-level community pollution sensitivity indices.

This may seem like a onerous task, to assign diatoms to a correct position on a phylogenetic tree, but with the availability and now widespread use of DNA barcoding techniques, it is becoming easier to get genetic data for microscopic assemblages than to identify cells to species. This means that samples can be fit to the phylogenetic clusters without needing to shift through samples. Further, if species are observed, which have not been properly assessed for their sensitivity, they can be assigned an expected sensitivity value based on their relatedness to assessed species.
The phylogenetic tree and species’ sensitivities (Fig. 2 in Keck et al.).
While diatom evolutionary history may not have been strongly influenced by environmental pollutants in the past –because they are relatively recent stressors; it is clear from Keck et al.’s results that closely related species are similarly sensitive to pollution. Other fields of applied management have also begun to incorporate evolutionary history in the design and assessment of applied actions –for example, restoration (Hipp et al. 2015). Evolutionary history can provide important insights and management tools for dealing with the consequences of environmental change.


Hipp, A.L., Larkin, D.J., Barak, R.S., Bowles, M.L., Cadotte, M.W., Jacobi, S.K., Lonsdorf, E., Scharenbroch, B.C., Williams, E. & Weiher, E. (2015) Phylogeny in the Service of Ecological Restoration. American Journal of Botany, 102, 647-648.
Keck, F., Bouchez, A., Franc, A. & Rimet, F. (2016) Linking phylogenetic similarity and pollution sensitivity to develop ecological assessment methods: a test with river diatoms (microalgae). Journal of Applied Ecology.
Stephens, P.A., Pettorelli, N., Barlow, J., Whittingham, M.J. & Cadotte, M.W. (2015) Management by proxy? The use of indices in applied ecology. Journal of Applied Ecology, 52, 1-6.
Wunsam, S., Cattaneo, A. & Bourassa, N. (2002) Comparing diatom species, genera and size in biomonitoring: a case study from streams in the Laurentians (Quebec, Canada). Freshwater Biology, 47, 325-340.

Saturday, February 6, 2016

Reining in traffic –looking to China for solutions?

Human impacts on landscapes are immense. Urban areas represent complete transformations of the geological, hydrological and ecological norms in landscapes. But while urban effects are concentrated to relatively small areas, the roads and rail lines feeding cities create a pervasive and diffuse network of negative impacts. Roads funnel rain runoff and can cause local flooding and this runoff also concentrates pollutants. Further, roads alter wildlife movement. For example, the fragmentation of formerly continuous forest in Florida is worsened by large busy roads, and black bears there are unable to move long distances to find mates. The result of this is that the Florida Black bear populations are getting smaller and more genetically inbreed.

Roads are created to meet traffic demands. The more people drive and the further they drive, the more roads we build. Cities around the world are growing, meaning that more cars are concentrated in small areas. The increase in automobile use also has direct environmental consequences. Cars, thanks to their internal combustion engines, add pollution to our local environments –carbon monoxide, particulate matter, and other toxins create smog, exacerbate respiratory ailments, and contribute to global warming.

More cars also means more traffic congestion and greater difficulty in getting from A to B, meaning that we spend more time travelling to, instead of being, somewhere. Heavy reliance on automobiles directly affects our quality life in both positive and negative ways.

1950s traffic jam in Los Angeles (from Wikipedia)
Given the undesirable consequences of cars, many cities try to reduce car use. In North America, cities employ a number of strategies, including: minor improvements to public transit (while often passing on the costs to riders), creating car free zones (which have been very modest in North America, whereas European cities have been much more successful –Montpellier, France is a great example), introducing tolls, and limiting parking in the city core. It is safe to say that the North American approach to dealing with traffic has been less than spectacular –just drive through Toronto or Los Angeles during rush hour.

Living in China for the past several months, I have been intrigued by how Chinese jurisdictions have dealt with traffic. And traffic was something that needed dealing with here. In the late 1990s and early 2000s, thousands of new cars were added to roads every single day.  The air quality in China is abysmal and having hundreds of millions of cars driving at the same time only make things worse. So governments in China decided to experiment with ways to reduce automobile use.

In China, much of the power to control automobiles resides with municipalities –they are the ones who set local traffic laws and issue license plates. From conversations with scientists from different regions of China, I have compiled ways different municipalities deal with traffic and reduce automobile use. Here are some of the ways that municipalities try to reduce automobile traffic:

1) Massive investments in public transit

There can be no real traffic solutions without building fast, efficient and affordable public transit. China has been a world leader in public infrastructure development over the past ten years. For example, Shanghai has one of the largest metro systems in the world, and has opened a new line every other year since 1999! They are currently building two new lines, which will give Shanghai 18 metro lines and about 400 stations. In Guangzhou, where I currently live, they also have a very modern and rapidly expanding metro system. Guangzhou currently has 8 lines with 4 more under construction! In all the Chinese cities I’ve been in, the metro systems are modern, efficient, heavily used, and very affordable. In Guangzhou, a bus ride works out to be about 35 cents US and a metro trip to the airport (the longest trip you can take in Guangzhou I believe) is about $1.15 US.

In Toronto, where I normally live, and like most other large North American cities, subway construction has not been sufficient to keep up with population growth. Local politicians seem to be unable to make the tough decisions to get public transit infrastructure built. But this infrastructure is the linchpin for any successful reduction in automobile usage.

2) Driving days

During the 2008 summer Olympics, Beijing created a system where cars were allowed on the roads only on certain days. Which days people could drive their cars depended on the last number of their license plates. This scheme was successful in reducing traffic congestion and air pollution. Since then, they have periodically reinstated this policy, especially during extremely bad air pollution days. I was there in early December, and road sharing was in effect then.

3) Making license plates really, really expensive (or difficult to get).

In Guangzhou, Beijing, and Shanghai, getting a car is easy, but getting a license plate, now there is the real hurdle. Since 2012, Guangzhou and other cities have severely limited the number of license plates issued, and now people can get a plate in one of two ways in these cities: by joining a lottery or going to an auction. In the lottery, a person submits an application and waits for the results. One person told me it took them three years to get their plate in the lottery. In the auction, the plates go to the highest bidder and the price for a license plate at auction has sky rocketed. A person told me that plates at auction now go for more than 60,000 RMB (about  $10,000 USD), which costs more than an economy car here! This person also quipped that the plates have become more of a status symbol than the actual car.

4) Your license plate will die

In Guangzhou and other cities, license plates expire. No, not like they expire in North America where you pay an annual license fee. They expire after 10 years and are no longer valid, and the driver must re-enter the lottery. 

5) Pay the toll

Many of the intercity highways have tolls here. While this is not a policy that affects travel behaviour within cities, it does influence driver choices traveling outside the city. Tolls only work when there are decent alternatives, and the rail system in China is excellent. There are frequent trains and many high speed lines in operation (where the trains go faster than 250 km/h). We don't have many toll roads in Ontario, but the one we have near Toronto, hwy 407, doesn't go into the city (so doesn't influence commuter decisions), and does not have viable options for alternative travel. This highway is an example of poor government policy and it was one of the worst policy decisions by a government who thought private companies should run public infrastructure. Its nothing more than a cash grab that doesn't serve the broader good. But I digress.

I have been struck by the variety of approaches and the experimental nature of policy making. What I mean by experimental, is that some policies seem to be ‘test run’ to see how people respond and if the policies result in the desired effects. China is able to institute creative and extreme measures because of the government’s unique ability to change policy without public debate. Often these policies are instituted overnight with little warning. In China, people seem to take government edicts with a “well, what can you do?” attitude. But if there is a country that can change the automobile culture, China is a good candidate. They did change what a family was with the one-child policy.

While most North Americans would certainly have a problem with the lack of transparency and seemingly impulsive nature of government decisions, China is providing the world with working examples of how to reduce the number of automobiles. It is clear to most, that without strong governmental leadership, a robust set of policies, and massive infrastructure investment, heavy automobile traffic will be unavoidable.

Tuesday, July 27, 2010

Enhanced biodiversity-ecosystem function relationships in polluted systems

*note: this text was adapted from an Editor's Choice I wrote for the Journal of Applied Ecology.

ResearchBlogging.orgIn this era of species loss and habitat degradation, understanding the link between biodiversity and functioning of species assemblages is a critically important area of research. Two decades of research has shown that communities with more species or functional types results in higher levels of ecosystem functioning, such as nutrient processing rates, carbon sequestration and productivity, among others. This research has typically used controlled experiments that standardize environmental influences and manipulate species diversity. However, a number of people have hypothesized that biodiversity may be even more important for the maintenance of ecosystem functioning during times of environmental stress or change rather than under stable, controlled conditions. It is during these times of environmental change that preserving ecological function is most important, as changes in function can have cascading effects on other trophic levels, compounding environmental stress. Therefore, explicitly testing how biodiversity affects function under environmental stress can help to inform management decisions.

Image from Wikimedia commons

In a recent paper in the Journal of Applied Ecology, Li and colleagues examine how algal biodiversity influences productivity in microcosms with differing cadmium concentrations. Cadmium (Cd) is a heavy metal used in a number of products and industrial processes, but it is toxic and Cd pollution is a concern for human populations and biological systems, especially aquatic communities. This is especially true in nations currently undergoing massive industrial expansion. In response to concerns about Cd pollution effects on aquatic productivity, Li et al. used algal assemblages from single species monocultures to eight species polycultures grown under a Cd-free control and two concentrations of Cd, and measured algal biomass.

Their results revealed that there was only a weak biodiversity-biomass relationship in the Cd-free teatment, which the authors ascribed to negative interactions offsetting positive niche partitioning. In particular, those species that were most productive in their monocultures were the most suppressed in polycultures. However, in microcosms with Cd present there were positive relationships between diversity and biomass. They attribute this to a reduction in the strength of competitive interactions and the opportunity for highly productive species to persist in the communities.

While a plethora of experiments generally find increased ecosystem function with greater diversity, Li et al.’s research indicates that the effect of biodiversity on function may be even more important in polluted systems. If this result can be duplicated in other systems, then this gives added pressure for management strategies to maintain maximal diversity as insurance against an uncertain future.

Li, J., Duan, H., Li, S., Kuang, J., Zeng, Y., & Shu, W. (2010). Cadmium pollution triggers a positive biodiversity-productivity relationship: evidence from a laboratory microcosm experiment Journal of Applied Ecology, 47 (4), 890-898 DOI: 10.1111/j.1365-2664.2010.01818.x