In honour of World Water Day, which is today, I thought we’d review some recent articles about that most essential element for gardeners.
Global water & climate change
A new report shows alarming changes in the entire global water cycle. Behind the changes expected under climate modelling scenarios, are troubling signs the entire global water cycle is changing. A research team led by Albert Van Dijk from Australian National University, analyses observations from more than 40, merged with data from thousands of weather and water monitoring stations on the ground. Drawing on those many terabytes of data, they paint a full picture of the water cycle over a year for the entire globe, as well as for individual countries. The findings are contained in a recently released report. The key conclusion? Earth’s water cycle is clearly changing. Globally, the air is getting hotter and drier, which means droughts and risky fire conditions are developing faster and more frequently.
Why rivers matter for the global carbon cycle
Writing from École Polytechnique Federale de Lausanne, Rebecca Mosimann notes that, until recently, our understanding of the global carbon cycle was largely limited to the world’s oceans and terrestrial ecosystems. Tom Battin, who heads EPFL’s River Ecosystems Laboratory (RIVER), has now shed new light on the key role that river networks play in our changing world. These findings are outlined in a review article commissioned by and published in Nature. Writing with a dozen experts and using the most recent data, this work demonstrates the critical importance of river ecosystems for global carbon fluxes—integrating land, atmosphere and the oceans.
Pollution & Water Treatment
When I was running the Canadian Environment Industry Association* in the late 1990s, one persistent problem with water treatment was removing pharmaceutical residues from drinking water. This has remained an issue for some classes of drugs but he last couple of decades have seen impressive advances. Prof. Dr. Juergen Kolb, an expert in environmental technologies at the Leibniz Institute for Plasma Science and Technology (INP), explains the current state of research. “We combine classical physical processes for wastewater purification with new technologies such as ultrasound, pulsed electric fields and plasma technology. This allows us to break down chemical compounds such as drug residues but also other man-made contaminants and convert them into harmless substances.” These methods have already proven their potential in various INP research projects. Currently, the approaches are being transferred to practice-relevant environments. “Our approach is currently mobile plants that can be used in hospitals, for example, where water contamination with pharmaceutical residues is particularly high. Particularly in view of the increasing number of antibiotic-resistant microorganisms, we see an acute need for action here,” Kolb adds. The technologies are also suitable for municipal sewage treatment plants as a fourth purification stage. The full article is titled: Innovative technologies to remove pharmaceutical residues from wastewater.
(CEIA no longer exists, but its Ontario provincial counterpart does. See Ontario Environment Industry Association.)
Living alongside the Ottawa River, stormwater management is a neighbourhood issue. Following flooding events in 2017 and 2019, the National Capital Commission has been busy rebuilding the retaining wall between us and the river. Sadly “green infrastructure” is not part of their engineering solution, which started instead with clear-cutting almost every tree along the river side of the wall.
Green stormwater infrastructure
Writing in Phys.Org, Leslie Lee of Texas A&M University discusses green stormwater solutions to the stormwater runoff issues caused by growing populations, more hard surfaces from expanding cities, and climate change-driven extreme weather events. To help cities grow their stormwater management strategy portfolios, Texas A&M AgriLife Research and AgriLife Extension staff at the center in Dallas are working on many stormwater-related projects. The idea behind green stormwater infrastructure (GSI) is to take downstream effects of water management into consideration and to promote more rainwater to infiltrate the soil and replenish aquifers, rather than simply running off into the nearest body of surface water.
Although many U.S. cities have been slow to adopt, a research review published in WIREs Water proposes strategies for municipalities and decision-makers to overcome barriers and use green stormwater infrastructure for long-term benefits.
How plants are inspiring new ways to extract value from wastewater
Scientists from The Australian National University (ANU) are drawing inspiration from plants to develop new techniques to separate and extract valuable minerals, metals and nutrients from resource-rich wastewater. The ANU researchers are adapting plant ‘membrane separation mechanisms’ so they can be embedded in new wastewater recycling technologies. This approach offers a sustainable solution to help manage the resources required for the world’s food, energy and water security by providing a way to harvest, recycle and reuse valuable metal, mineral and nutrient resources from liquid wastes. The research is published in New Phytologist.
Potential Contaminants in Residential Rain Barrel Water
In a new paper on ResearchGate, Linda Chalker Scott notes residential gardeners often use rain barrels to collect rainwater from roofs as a supplement to summer irrigation. Rainwater is a natural and unchlorinated water source for aquatic plants and animals. However, rooftop runoff can be contaminated by chemical and biological pollutants from atmospheric deposition, bird droppings, and the roofing material itself. This publication examines the state of knowledge on residential rain barrel water safety in North America over the last 20 years. Among the simple, research-based practices gardeners can use to take advantage of collected rainwater, while also reducing the risks of contamination exposure are:
- Knowing your local pollution issues
- Avoid collecting rainwater: when air quality is low (smoggy, temperature inversions, low wind speeds); if you have recently used a moss removal product on the roof; or if pesticides have been recently applied nearby.
- Use good garden hygiene, including: keeping your barrels well sealed, and using mosquito netting on the top of them; not drinking rainwater or touching your wet hands to your mouth or eyes; washing your hands after handling rainwater; and cleaning the barrels regularly.
- Wash garden produce before eating it.
- Install a diverter for the first flush of rain to capture the worst of the contaminants.
Closer to Home
Ontario wetlands under threat
Angelica Marie Sanchez from University of Waterloo, quotes Dr. Rebecca Rooney, a wetland ecologist and professor in the Department of Biology. “Wetlands are a portfolio of ecosystem services: including flood prevention, breaking down pesticides, storing large amounts of carbon, and provide habitat for more than 32% of Ontario species at risk who rely on these wetlands to mitigate climate change.” Canada is home to 25% of the world’s wetlands. But according to Rooney, Canada has lost more than 60% of its wetlands over the years. In agricultural areas, wetlands have been drained to make space for farming. While in urban and suburban areas, Canada has lost the majority of its wetlands due to them being drained for housing development. Stormwater ponds are engineered solutions created to effectively replace wetlands across Ontario. However, these ponds only address some of the problems including flood prevention, but they need to provide the full portfolio of ecosystem services that wetlands provide.
While the More Homes Built Faster Act, formerly known as Bill 23, aims to address the housing crisis in Ontario, it will be devastating for the province’s wetlands. The proposals posted to the Environmental Registry of Ontario included changes to the Ontario Wetland Evaluation System, which is the instrument the provinces uses to determine whether a wetland gets classified as provincially significant. “… Unfortunately, the changes that are being proposed to the Ontario wetland evaluation system will dramatically undermine its efficacy and endanger wetlands across Ontario,” says Rooney. “There is a huge amount of scientific evidence that connects these pockets of wetlands into a whole integrated network,” says Rooney. “If you start chipping away at the wetlands and you destroy one piece of it, the whole network is going to suffer under the current proposals.”
Rooney encourages people to act by learning more about the act and its impact on Canada’s wetlands.
Arctic river channels changing
A team of international researchers monitoring the impact of climate change on large rivers in Arctic Canada and Alaska determined that, as the region is sharply warming up, its rivers are not moving as scientists have expected. Dr. Alessandro Ielpi, an Assistant Professor with UBC Okanagan’s Irving K. Barber Faculty of Science, is a landscape scientist and lead author of a paper published in Nature Climate Change. Dr. Ielpi says the assumption of faster river channel migration owing to climate change has dominated the scientific community for decades. “But the assumption had never been verified against field observations,” he adds. To test this assumption, Dr. Ielpi and his team analyzed a collection of time-lapsed satellite images—stretching back more than 50 years. They compared more than a thousand kilometers of riverbanks from 10 Arctic rivers. “We found that large sinuous rivers with various degrees of permafrost distribution in their floodplains and catchments, display instead a peculiar range in migration rates,” says Dr. Ielpi. “Surprisingly, these rivers migrate at slower rates under warming temperatures.” One reason why is that warmer temperatures mean more vegetation, which helps to stabilize river banks.
Good News Stories
How Las Vegas declared war on thirsty grass
Writing in the LA Times, Molly Hennessy-Fiske and Ian James report on how Las Vegas has emerged as a leader in water conservation, and some of its initiatives have spread to other cities and states that rely on the shrinking river. Its drive to get rid of grass in particular could reshape the look of landscapes in public and private spaces throughout the Southwest. In 2002, as the reservoir level dropped, the Southern Nevada Water Authority used more than its allocation of Colorado River water. At that point, the agency’s leaders decided to pivot quickly toward conservation. Cash rebates to encouraged residents to rip out lawns and put in landscaping with desert plants. In 2003, the Las Vegas area’s consumption of Colorado River water shrank more than 16%. Those conservation gains continued as the area’s water suppliers strengthened their rules, targeting grass. As the article details, not everyone is happy with the restrictions, but they are helping to conserve valuable water resources.
Drought detection on the cheap
Meanwhile researchers at University of Barcelona recently published a study in the journal Trends in Plant Science that presents a set of techniques that enable researchers to detect and monitor drought stress in plants in a cheap, easy and quick way. The study responds to the need to establish effective and low-cost protocols to easily detect and study how droughts affect plants. Specifically, the authors present a battery of very accessible techniques that can be applied with basic laboratory equipment: precision balance, microscope, centrifuge, spectrophotometer, oven, camera and computer.
In other good news Everglades restoration moves closer to reality with a crucial groundbreaking. Elsewhere Albania’s ‘wild river’ now a national park.
Gardening at Last 