Thursday 31 May 2018

Part 4 - Wetlands Against Climate Change: "Keeping it Clean: Wetlands Purifying Water!"

In Canada we expect access to safe and reliable drinking water, and per person, Canada has the world’s largest supply of freshwater. Newfoundland and Labrador is no exception with an abundance of ponds, lakes, rivers and wetlands. However, when we take a look worldwide, climate change is threatening our access to clean water.

The Human Right to Water (Image from UN Water Decade Programme)
The World Health Organization (WHO) in partnership with UNICEF, reported in 2010 that 884 million people did not have access to clean drinking water. At that time, the United Nations made access to clean water a human right. This human right is being threatened in some surprising ways due to climate change.

First, climate change can effect our water quality. Extreme weather events can stir up silt and increase runoff and warmer temperature can cause the over production of biological and chemical elements. For example storm sewers can be overwhelmed by heavy rain and flash floods, leading to untreated water entering our drinking water supplies. 

Also the way we produce clean water impacts climate change. When water is treated in plants that use large amounts of energy, which in many cases are powered by coal, natural gas, oil and other fossil fuels this contributes to greenhouse gas emissions. Also, the demand for clean water has increased the use of bottled water. As more bottles are manufactured and shipped around the world this also contributes to greenhouse gases emissions. Coming at us from different angles, climate change impacts our clean water on the global scale.

Bottled Water (Image from Readers Digest)
Wetlands can help! Believe it or not, natural wetlands have the power to clean water! They offset the production of greenhouse gases by doing what they do naturally, purifying water in our environment. The process begins when flowing water meets a wetland. This water can be from rivers, lakes, sewage or agricultural runoff. Once the water meets the wetland it moves very slowly because the thick vegetation, the absorbent peat soils, and the network of roots are able to hold water in the wetland for an extended period of time. This allows for physical, chemical, and biological processes to clean the water.

Physical processes in wetland habitats include the trapping sediment and excess minerals. After a heavy rain fall or extreme weather event, such as a hurricane or flooding, sediment can be stirred up. These heavy sediments can clog our waterways and treatment plants, kill fish, and smother bottom feeding wildlife and plants.When these sediment heavy waters pass through a wetland, the habitat acts like a sieve, allowing sediment to settle at the bottom before it reaches water supplies and wildlife habitat. According to the Ecological Society of America, wetlands can trap and retain 80 – 90% of sediment from runoff!

Besides silt and sediment, wetlands also help remove potentially harmful elements. Phosphorus is a naturally occurring element that is essential for life, but in excess it can lead to kidney disease. Excess phosphorous can end up in water supplies though over fertilization of agricultural crops. In its particulate (or solid) form, it is first removed by the wetland using the physical processes of sedimentation. Once this particulate phosphorous settles out in the slow moving, highly vegetated water of wetlands, chemical processes remove even more phosphorus. Dissolved phosphorus, in the form of liquids and gases, accumulate, react with the wetland sediments, and eventually precipitates (solidifies) into other harmless elements including aluminum, iron and calcium phosphorus.

Nitrogen and phosphorus cycles in a wetland. (Image from IAN University Of Maryland)
Wetlands also use biological processes to filter excess elements and pollution from water. Plants, algae and bacteria uptake and transform chemical elements that in excess, are considered pollutants. Like phosphorus, high nitrogen levels are also present in areas where heavy fertilizer is used. Ammonia, which is in many fertilizers, converts to nitrates when exposed to water and high levels of nitrates can cause many problems including methemoglobinemia (blue baby syndrome) that inhibits the flow of oxygen in the bloodstream of infantsNitrogen removal in wetlands is a naturally occurring process. Microbes found on plant roots and stems, take up nitrogen and convert it into harmless nitrogen gas and release it into the air. Wetlands are able to eliminate 70 –90% of entering nitrogen through this process.

Constructed wetland in Stephenville, NL (Image from
Wetlands have proven so effective at purifying water, companies around the world are constructing wetlands to clean municipal waste water. Constructed wetlands are a system of wetland beds that can mimic some of the filtration power of natural systems. Several municipalities in Newfoundland have opted for constructed wetland systems including Marystown, Appleton, and Stephenville. Wastewater is first passed through a screen to remove large non-organic materials, then the water passes through several wetland beds where it is filtered and able to return to the natural environment in lakes and rivers. Any settled materials are collected and sent through an additional wetland beds where the native plants re-mineralize the sediments and create compost that can be used for landscaping. 

An illustration of a constructed wetland system (Image from

Constructed wetlands can be appropriate for small communities, but do not replace natural wetlands and do not always provide the many other services provided by natural wetlands such as flood control, carbon sequestration and wildlife habitat.

Wetland in Carmanville, NL (Image from SAM NL)

We are learning more about wetlands, their power as natural water filters, and the many other ecosystems services they provide in the face of climate change.  Unfortunately, in Canada we lose 80 acres (32 hectares) of wetland per day. Conserving wetlands, and better understanding their functions, can assist us in keeping water clean by mitigating the effects of climate change.

What can YOU do to conserve wetlands that purify our water?

1) Use natural fertilizers on our home gardens

2) Take your fertilizers, pesticides, oil and other toxic wastes to the Household Hazardous Waste disposal station nearest you

3) Plant native vegetation on your property and in wetland restoration projects (Click to find our link on how to enhance your backyard habitat)

4) Volunteer to monitor and clean municipal and urban waterways – organizations like NA ACAP
, Municipalities, and WWF regularly host cleanups where you can do your part!

5) Conserve and protect natural wetlands in our municipalities by supporting parks and organizations committed to protecting wetlands and natural areas

6) Support proper municipal planning that considers impacts on waterways as part of all urban, industry and agricultural development. Attend your local public consultations whenever your municipality asks, and share your concerns about wetlands and waterways being conserved for the future


Abydoz. “Projects and Technology”  Website.

Ducks Unlimited Canada. “How wetlands take care of Canada’s Water” . Website.

Ducks Unlimited Canada. “Water” . Website.

Ducks Unlimited Canada. “Making a Dam Difference at The Etang Stater Wetland “ . Website.

Ecological Society of America “Reveling secrets about… natural water purification” PDF.

Grace Communications Foundation, Water Program “The Impact of Climate Change on Water Resources” Website.

Livestrong “Too Much Phosphorus in the Body” Website.

Michigan Environmental Education Curriculum, Wetland Ecosystems “How to wetlands filter harmful substances” . Website.

National Park Service. “Water Filtering of Wetlands” . Website.

Nature “Cool Green Science: Building wetlands for clean drinking water” Website.

(Perma)Culture and Sanity “Wastewater Treatment and Constructed Wetland part I” Website.

Ramsar. Factsheet, “Wetlands: Why Should  I care?” . PDF.

Ramsar. “Wetlands; a sustainable solution for water purification and security” . Website.

Sciencing. “How do wetlands purify water?” . Website.

The Wetlands Initiative. “Value of Wetlands: Cleaner Water” . Website.

The Wetlands initiative. “Ask a Scientist: Nutrient Removal” . Website.

UN Decade programme on advocacy and communication (UNW-DPAC) “The Human Right to Water” PDF.

UN Water “International Decade for Action ‘Water for life’ 2005 – 2015” Website.

United States Environmental Protection Agency. “Climate Impacts Water Resources” . Website.

Wikipedia “Phosphorus” Website.