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As intense heatwaves grip the United Kingdom, Spain, France and Portugal—at times exceeding temperatures of 40 C—as well as parts of North America and Asia, lakes around the world are feeling the heat from climate change, which is creating a cascade of ecological and environmental issues.

Northernmost lakes are considered the bellwethers of environmental change, but research shows consequences of climate change can affect any of the more than 100 million lakes in the world. 

To get a cohesive picture of how climate change is threatening lakes, Reader R. Iestyn Woolway of Bangor University, Wales, Associate Professor Sapna Sharma of York University, and Distinguished University Professor John Smol of Queen’s University have reviewed and synthesized available studies on freshwater lakes from across the globe.

The research team found that the effects of climate change on lakes are often cumulative. Warmer water temperatures lead to changes in stratification regimes, declines in dissolved oxygen, a higher risk of cyanobacterial algal blooms, and a loss of habitat for native cold-water fish. It can affect not only water quality and quantity, but also cultural and recreational activities, and local economies. 

“Climate change has far-reaching social and ecological repercussions, but the impacts of climate change, combined with other environmental pressures, are often little understood and the significance of them has not been appreciated at a global level,” says Sharma of York’s Faculty of Science. “There is still much work to be done.”

Warmer air temperatures can impact winter ice cover in the case of northern lakes. Ice loss is one of the most blatant consequences of climate warming on lakes, which can increase winter evaporation rates and water temperatures, and lead to a multitude of physical and chemical effects, including greater salinity. The global mean annual evaporation of lakes is expected to increase by 16 percent by century’s end. In addition, lower levels of precipitation can also have a significant effect on lake levels. 

“The ecological consequences of climate change coupled with the impacts of extreme climate events are already occurring in lakes globally and will continue to do so in the future, often without warning or time to adapt,” says Woolway. “The results of these kinds of changes have been felt in lakes from Algonquin Park in Ontario to Lake Chad in Africa, the English Lake District in the U.K. to Lake Mead in the United States.”

Declines in water levels can be severe in some regions. Historically ranked as one of the largest lakes in Africa, Lake Chad, which borders Chad, Cameroon, Niger and Nigeria, has shrunk considerably because of decreases in local precipitation and discharge from its catchment, as well as increased evaporation. 

“Events like an earlier summer season can also cause mismatches in fish spawning and foraging, often with widespread ramifications across the food web. Although a ‘longer summer’ may be welcome to many cottagers and campers, such weather conditions increase the risk of algal blooms, and especially cyanobacterial blooms, which can have far-reaching ecological consequences and even make drinking water toxic,” says Smol. 

Some of the effects of climate change are creating conditions where lakes are losing oxygen needed for fish and other aquatic species. This deoxygenation can be made worse by cyanobacterial blooms.

“Algal blooms can block sunlight from reaching the deeper waters and bacterial decomposition of sedimented algae can lead to a decrease in oxygen for deep-water fish and other aquatic life,” says Woolway. “In addition, episodic storms can cause nutrients to suddenly wash into lakes and foster the development of cyanobacterial blooms.”

A decline in the availability of safe drinking water caused by harmful algal blooms is considerably worse when combined with a reduction in water quantity. In 2014, a cyanobacteria bloom in Lake Erie shut down the water supply in Toledo, Ohio, while a massive toxic cyanobacterial bloom in Lake Taihu, China, shut down the water supply for two million people for a week in Wuxi city

“In Ontario, reports of algal blooms have not only increased, but have been reported as late as November, something that was typically not the case in previous years,” says Sharma. “These blooms could also affect tourism and lakeside property values.”

Seven years ago, Algonquin Park banned overnight camping on remote and nutrient-poor Dickson Lake because cyanobacterial blooms caused health concerns. A sediment-based study determined that these blooms were new to the lake and no comparable events had occurred in the last century, but that’s changing.

Warmer water temperatures, algal blooms, earlier onset, and longer periods of thermal stratification, combined with lower dissolved oxygen concentrations can have important cumulative and potentially negative effects on aquatic organisms, such as fish.

“The effects of climate change also interact synergistically with multiple environmental stressors exacerbating problems with water quantity and quality, including salinization, contamination, and the spread of invasive species,” says Smol. “As humans can’t survive without water, a better understanding of how climate change affects lake function is needed along with recognition of early warning signals.”

The researchers hope that recent advances in technology, such as remote sensing and environmental DNA, combined with a move to work beyond traditional silos, will allow for a better understanding of lake responses in the future. Their study is published in BioScience.

For the United Nations’ Sustainable Development Goal of equitable access to clean water to be realized by 2030, the inclusion of diverse voices from researchers worldwide, including the Global South, and the cross-pollination of ideas across disciplines will be essential.

FOR MORE INFORMATION: https://phys.org/news/2022-07-lakes-hot-climate-cauldron-issues.html

The continental shelf is the submerged extension of a continent and as such it is at the crossroad of terrestrial, oceanic and atmospheric influences. This confluence is the lead driver of the high biological productivity that often characterizes the continental shelf regions. Their productivity is not only critical to the ecosystems that it sustains but also to the livelihood of coastal communities such as tourism, fishing, aquaculture and more.

Anthropogenic climate change is expected to have profound implications on shelf dynamics as changes in local atmospheric circulation, heat, and evaporative fluxes can significantly affect the balance between surface fluxes, horizontal transports and vertical mixing. In addition, changes to freshwater discharge from the continent whether by land management, climate driven rainfall or man-made modified freshwater discharge, have large impacts on shelf dynamics and may mitigate or exacerbate changes associated with climate. 

One region where these changes are particularly evident is the Gulf of Mexico. The West Florida coast is under the influence of a significant number of freshwater inputs. They drain fresh water from precipitation (direct or delayed, local or regional) from rivers, streams, lakes, and canals into the near shore, majorly contributing to the estuarine properties of West Florida Shelf waters. This fresh water usually expands westward and southward over the shelf, and contributes to the riverine properties of the inner shelf waters.

South Florida is currently implementing the most expansive restoration project ever undertaken to restore the Greater Everglades Ecosystem. The Comprehensive Everglades Restoration Plan is restoring the quantity, quality, timing and distribution of freshwater flows to its pre-drainage levels.

While it seems possible to assess the effect of changes in water runoff locally, there are also long-range implications at depth, on the inner and mid shelf, that remain to be understood.

A researcher from Florida Atlantic University’s Harbor Branch Oceanographic Institute, in collaboration with Florida International University, conducted a study that provides an assessment of the potential effects of climate warming and water management of the West Florida Shelf dynamics during two particular events that affect its hydrology through the lens of a very high-resolution model.

For the study, they evaluated, in a high-resolution simulation (1.5 kilometers), the separate and combined effects of freshwater discharge management and climate warming by 1 degree Celsius on the Loop Current intrusions on the West Florida Shelf and its dynamics, in the sub-tropical western Atlantic. 

Results, published in Bulletin of Marine Science, showed that based on a one-year simulation in which a Loop Current and its eddy intruded on the West Florida Shelf, either the increase of freshwater discharge or the climate warming led to a change in the stratification properties of the West Florida Shelf significant enough to affect the type of Loop Current intrusions. Increased freshwater discharge contributed to the intensification of shelf water mixing that favors surface intrusion of Loop Current waters. In contrast, 1 degree Celsius warming led to increased shelf waters stratification that favors bottom intrusions.

“Either type of intrusion leads to a different oceanographic regime on the shelf to which the ecosystem might respond differently,” said Laurent Chérubin, Ph.D., senior author, a physical oceanographer who specializes in ocean dynamics and a research professor at FAU Harbor Branch. “Our study suggests, however, that increased freshwater discharge could mitigate the effect of climate warming on the West Florida Shelf by reducing shelf waters stratification.”

Researchers also analyzed the West Florida Shelf response to cold air outbreaks that are common in the fall and winter months. Results showed that under a warmer climate, the increased stratification due to the freshwater discharge at the end the boreal summer wet season is canceled by the warmer climate and reduces the available potential energy on the shelf, limiting coastal upwelling, instabilities, and shelf convection.

“The West Florida Shelf is under the influence of a large number of estuarine systems and bays that influence the baroclinicity of the flow on the shelf,” said Robert Burgman, Ph.D., co-author and an associate professor who specializes in climate dynamics and atmospheric science in FIU’s College of Arts, Sciences & Education. “Changes in salinity and/or nutrient patterns have had significant direct and indirect impacts on the water column and attached communities, with documented micro- and macroalgal blooms, mass mortality of seagrasses, fragmentation of seascapes, sponge die-offs, and declines in pink-shrimp catches.”

The current river discharge in South Florida is the product of a historical effort that was originally aimed at draining water from the Everglades region in Florida. The modification of the freshwater flows caused by the construction of the Central and Southern Florida Project water-drainage system was completed in the 1960s. This system, consisting of canals, pumps, levees, and other control structures, was designed to prevent flooding of urban and agricultural areas and has altered the regional hydrology, reducing the total amount of freshwater reaching the coastline.

From ocean depths to mountain peaks, humans have littered the planet with tiny shards of plastic. We have even absorbed these microplastics into our bodies—with uncertain implications.

Images of plastic pollution have become familiar: a turtle suffocated by a shopping bag, water bottles washed up on beaches, or the monstrous “Great Pacific Garbage Patch” of floating detritus.

Millions of tonnes of plastic produced every year, largely from fossil fuels, make their way into the environment and degrade into smaller and smaller pieces.

“We did not imagine 10 years ago that there could be so many small microplastics, invisible to the naked eye, and that they were everywhere around us,” said Jean-Francois Ghiglione, a researcher at the Laboratory of Microbial Oceanography in France.

“And we could not yet envisage finding them in the human body“.

Now scientific studies are increasingly detecting microplastics in some human organs—including “the lungs, spleen, kidneys, and even the placenta,” Ghiglione told AFP.

It may not come as much of a shock that we breathe in these particles present in the air, in particular microfibres from synthetic clothing.

“We know that there’s microplastics in the air, we know it’s all around us,” said Laura Sadofsky, from the Hull York Medical School in the UK.

Her team found polypropylene and PET (polyethylene terephthalate) in lung tissue, identifying fibres from synthetic fabrics. 

“The surprise for us was how deep it got into the lungs and the size of those particles,” she told AFP.

In March, another study reported the first traces of PET found in the blood.

Given the small sample of volunteers, some scientists say it is too early to draw conclusions, but there are concerns that if plastics are in the bloodstream they could be transported to all organs.

In 2021, researchers found microplastics in both maternal and foetal placental tissue, expressing “great concern” over the possible consequences on the development of the foetus. 

But concern is not the same as a proven risk.

“If you ask a scientist if there is a negative effect, he or she would say ‘I don’t know’,” said Bart Koelmans, professor in Aquatic Ecology and Water Quality at Wageningen University.

“It’s potentially a big problem, but we don’t have the scientific evidence to positively confirm what are the effects, if any.”

One hypothesis is that microplastics could be responsible for certain syndromes that weaken human health.

While scientists have recently identified their presence in the body, it is likely that humans have been eating, drinking and breathing in plastics for years.

In 2019, a shock report by the environmental charity WWF estimated that people are ingesting and inhaling up to five grams of plastic per week—enough to make a credit card.

Koelmans, who contests the methodology and results of that study, has calculated the amount is closer to a grain of salt.

“Over a lifetime, a grain of salt per week is still quite something,” he told AFP.

While health studies on humans have yet to be developed, toxicity in certain animals reinforces concerns.

“Small microplastics invisible to the naked eye have deleterious effects on all the animals that we have studied in the marine environment, or on land,” said Ghiglione.

He added that the array of chemicals found in these materials—including dyes, stabilisers, flame retardants—can affect growth, metabolism, blood sugar, blood pressure and even reproduction. 

The researcher said there should be a “precautionary” approach, urging consumers to reduce the number of plastic-packaged products they buy, particularly bottles.

Earlier this year, the United Nations began a process to develop an internationally binding treaty to tackle the global plastic scourge.

It has warned that the world is facing a pollution crisis to match the biodiversity and climate crises.

While the health implications from plastics are not known, scientists do know the impacts of indoor and outdoor air pollution, which experts from The Lancet Commission on pollution and health have estimated caused 6.7 million people to suffer an early death in 2019.

Some 460 million tonnes of plastics were used in 2019, twice as much as 20 years earlier. Less than 10 percent was recycled.

Annual production of fossil-fuel-based plastics is set to top 1.2 billion tonnes by 2060, with waste exceeding one billion tonnes, the Organisation for Economic Co-operation and Development said last month.

“People cannot stop breathing, so even if you change your eating habits you will still inhale them,” said Koelmans.

FOR MORE INFORMATION: https://phys.org/news/2022-07-theyre-microplastics-oceans-air-human.html

The Nature Conservancy’s Joseph Schmidt envisions a future for the Lake Worth Lagoon. In it, American oystercatchers forage the shoreline, mangroves and oysters filter pollution, and kayaks glide from restored island to restored island. In turn, those islands help protect human development.

his vision is one step closer to reality with the completion of the the Palm Beach Resilient Island Project, which rebuilt an eroded island in West Palm Beach with green infrastructure such as oyster beds and mangroves in lieu of seawalls.

The hope is that the island will both protect nearby shoreline by softening the brunt of storm surge, while also buttressing marine habitat: Nesting sites attract shorebirds while mangroves and oysters cleanse polluted waters and create habitats for shrimp, snook, mangrove snapper and even juvenile grouper.

The project is spearheaded by Schmidt, the interim climate strategy director at the Florida chapter of the Nature Conservancy, and the Palm Beach County Department of Environmental Resources Management. It marks the latest effort to strengthen the county’s shorelines against climate change.

Construction began in mid-March and was completed July 1. The final step, planting mangroves, is scheduled for August.

“Florida is very vulnerable. Everywhere here is not too far from the coast and our low-lying topography makes it even more vulnerable during storms,” Schmidt said. “So if this works well, we can replicate it elsewhere.”

Funding for the project came from both private and public sources. The Nature Conservancy provided $300,000 through funds from the Batchelor Foundation and the Carrier Corporation, while the Florida Department of Environmental Protection also provided $300,000 through its Resilient Coastlines Program.

Green infrastructure

Prior to the project, the one-acre island had eroded, and barely poked out of the water during low tide.

“Increased traffic, high tides, sea level rise have really taken its toll,” Schmidt said, “so this remnant of an island was much larger in the past.”

County crews built up the island with leftover soil from dredging projects in the Intracoastal Waterway.

They then ringed the island with different elements. An outer ring of limestone boulders buffers the impact of storms and floods that could otherwise beat against coastlines or uproot mangroves. Inside that, they placed an array of small limestone rocks ideal for oyster growth. Both the boulders and the rocks have enough nooks and crannies to double as homes for small fish and invertebrates.

Closer to the island there’s a shallow area for mangrove and seagrass—more habitat for sea life.

“Living shorelines and using green infrastructure is definitely not new,” Schmidt said of the project. “But arranging them specifically for coastal resilience is relatively new, and it’s kind of at its early infancy.”

The lagoon’s health

Water quality treatment is especially necessary in the central portion of the lagoon, where the project lays. The county’s Lake Worth Lagoon Management Plan, updated in 2021, says the central portion has “markedly diminished water quality and biodiversity” since it’s the furthest away from tidal flushing.

Outputs from hundreds of square miles of runoff from the C-51 Canal, among other canals, feed into the lagoon. The outflow brings with it polluting nutrients, algae and fine sediments that prevent sunlight from reaching the lagoon’s floor.

“When it rains a lot, there’s not any place to store the water,” said Lisa Interlandi, an attorney for the Everglades Law Center. “So it’s basically all discharged into the lagoon with whatever it has with it—everything from sediments to lawn clippings to what people have sprayed on their lawns, to the harmful residual chemicals in Lake Okeechobee.”

Living shoreline projects and restored lagoon islands aim to chip away at the damage done by a century’s worth of human development.

Both the mangroves and oyster beds will filter water and absorb carbon dioxide, while stabilizing the soil to keep the island intact.

A look forward

Where there was once scant habitat for sea turtles and shorebirds, there are now nesting sites and fertile bottom for soon-to-be mangroves.

Even with the mangroves still missing, American oystercatchers, a protected species of shorebird, have already started foraging around the island. The species only returned to the lagoon within the last decade—a response chalked up to restoration efforts.

“Since we’ve been building projects over the past 30 years, we’ve had four pairs take up residence in our restoration areas,” said David Carson, senior environmental analyst for the Palm Beach County Department of Environmental Resources Management. “Since 2005, we’ve had 40 pairs of chicks fledged out of [restored areas].”

With the arrival of oystercatchers comes a revived vision of the lagoon, the county’s largest estuary. As more of the bright orange bills peck through the sand of the lagoon’s latest island, other visitors—winged and not—could follow suit.

Now, other coastal communities dependent on the lagoon are requesting islands, too, says Gregg Weiss, commissioner and vice mayor of Palm Beach County’s second district and member of the Lake Worth Lagoon Initiative Steering Committee.

Weiss said the next areas to receive them will likely be along Lake Worth Beach or further south near Lantana and Boynton.

“It took many years for us to understand the impact we were having,” says Weiss, “and then try to figure out how to undo some of the damage done by previous generations.”

FOR MORE INFORMATION: https://phys.org/news/2022-07-rebuilding-island-lake-worth-lagoon.html

As any gardener or farmer can tell you, nitrogen and phosphorus are chemical elements found in soils and fertilizers that plants need to grow. They also know different ratios of nitrogen and phosphorus are ideal or detrimental for different types of plants and crops.

Nitrogen and phosphorus also play a powerful role in lakes and can alter the clear and pristine waters of low-nutrient lakes. But while considerable efforts have been made to monitor the amounts of each nutrient element separately, limited research has assessed how the ratio of nitrogen to phosphorus being supplied to lakes might also alter algae growth and water quality in consequential ways. 

Now a team of researchers led by scientists from the University of Montana’s Flathead Lake Biological Station has examined nearly 40 years of nutrient dynamics in Flathead Lake. This unique dataset, assembled by the FLBS Flathead Monitoring Program, documents a sustained imbalance between nitrogen and phosphorus that likely has significant ecological consequences in Flathead Lake, as well as other low-nutrient ecosystems.

Their work was published July 11 by the Proceedings of the National Academy of Sciences.

“Since the early 1990s, I’ve worked to better understand when and where nitrogen and phosphorus limit the growth of lakeorganisms, such as plankton,” said FLBS Director Jim Elser, a member of the National Academy of Sciences and the lead author on the study. “It turns out that strong imbalances in the ratio between nitrogen and phosphorus in ecosystems and organisms can have big impacts. I wanted to see if this was going on in Flathead Lake.”

For over a century, research and monitoring programs at FLBS have served as the first line of defense against ever-looming threats to the renowned water quality of the Flathead watershed. The primary threats of nutrient pollution and invasive species have remained the bio station’s oldest foes in the fight to sustain the lake’s condition and excellent water quality.

Flathead Lake is known for its clean and clear water, largely because the geology encompassing its watershed is ancient and low in nutrients, especially the nutrient phosphorus. This means there are very low levels of nutrients that can be weathered from the bedrock to reach the lake through rainstorms and snowmelt. Therefore, naturally there are low levels of nutrients available for lake algae to grow, and Flathead Lake remains clear and blue instead of green and murky.

This low background of naturally supplied nutrients makes Flathead Lake very sensitive to human-driven inputs of nutrients. Such human-driven inputs of nutrients into Flathead Lake and associated algal blooms raised concerns in the 1970s and ’80s. Subsequently, research conducted by FLBS scientists led to nutrient reduction measures in the Flathead watershed, including one of the nation’s largest bans on phosphorus-containing laundry detergents and a multimillion-dollar overhaul of local wastewater treatment facilities to remove phosphorus to very low levels.

But in recent years, Elser and his colleagues began to wonder if monitoring nitrogen and phosphorus in isolation was enough. Given his long history in developing and testing the theory of ecological stoichiometry—the study of the balance of multiple chemical elements in ecological interactions—Elser was eager to find out. 

“We found that the overall levels of nitrogen and phosphorus in Flathead Lake and its surrounding rivers and streams, while variable within years and year-to-year, are low but not increasing,” said Elser. “In fact, nitrogen and phosphorus levels coming into Flathead Lake from its larger rivers actually appear to be slowly declining. This is great news for the water quality and clarity in our beloved Flathead Lake, while water quality in many of the world’s lakes is declining due to increasing nutrient inputs.”

Then came a surprising development. While the overall levels of nitrogen and phosphorus in Flathead Lake weren’t increasing, the researchers discovered that the lake has sustained a high ratio of nitrogen to phosphorus across a span of four decades, often reaching values that greatly exceed the normal nitrogen-to-phosphorus recipe that matches the needs of most phytoplankton, the lake’s microscopic floating algae.

To put it another way, just as humans benefit from a well-balanced breakfast or farmers apply a fertilizer with the appropriate ratio of nitrogen to phosphorus for specific crops, microorganisms that make up the foundation of a lake’s food web depend on a very specific ratio of nutrients. When the ratio between nitrogen and phosphorus is high, as it is in Flathead Lake, plankton growth is likely limited by lack of available phosphorus for much of the year. 

Through a series of experiments, the team of researchers showed that Flathead Lake phytoplankton are phosphorus-limited. This means the algae are forced to build cells that have low content of phosphorus, making them not particularly nutritious. For the tiny lake animals, zooplankton, which eat those phytoplankton and thereby sustain the lake’s high transparency, this amounts to the equivalent of a “junk food” diet. As a result the zooplankton also become phosphorus-limited and their abundances low.

Finally, the team showed that the strong nitrogen-to-phosphorus imbalance in Flathead Lake sets the stage for potential production of the greenhouse gas methane. This occurs when phosphorus-hungry microbes start to scavenge phosphorus from organic molecules and produce methane as a byproduct.

These findings have implications not only for Flathead Lake but also for lakes globally. Wastewater treatment systems, agricultural runoff and urban influences are increasingly recognized as contributing to nitrogen-to-phosphorus imbalance in a variety of situations. 

“At Flathead Lake, implementation of wastewater treatment processes that more effectively remove nitrogen would help balance the lake’s nitrogen-to-phosphorus ratio,” Elser said. “Regionally, a reduction of the atmospheric transport of nitrogen, which occurs through fossil fuel combustion or volatilization of agricultural fertilizers or animal wastes, would also help reduce nitrogen inputs to the lake.”

When it comes to the building blocks of our lake ecosystems, in other words, nutrient balance matters.

FOR MORE INFORMATION: https://phys.org/news/2022-07-nutrient-imbalance-flathead-lake.html

In the fall of 2023, a U.S. rover will land at the south pole of the moon. Its mission: to explore the water ice that scientists know lurks within the lunar shadows, and which they believe could help sustain humans who may one day explore the moon or use it as a launching pad for more distant space exploration.

NASA recently selected Kevin Lewis, an associate professor in the Krieger School’s Department of Earth and Planetary Sciences who has also worked on missions on Mars, as a co-investigator of the mission. Using part of the rover’s navigational system, he plans to explore the moon’s subsurface geology from his office in Olin Hall.

“I have been on other rover missions, but on Mars, so I’m a little bit new to the moon,” Lewis said. “We’re going to see into shadows that have never seen the sun, let alone been seen by humans. So it could be a very different type of surface than we’ve seen in other photos of the surface of the moon.”

Drier than a desert

Most of the moon is completely without water. That’s because of the way the satellite was formed, in a giant impact between the proto-Earth and a Mars-size object. Temperatures were high enough not only to melt rock, but to vaporize it, causing a cloud of rock vapor to orbit Earth. The vapor eventually coalesced to form the moon.

Those temperatures were also high enough to drive off any water, not even leaving appreciable traces trapped within rocks the way it is on Earth. But over time, meteors and comets containing water ice bombarded the moon, sending ice molecules hopping around the lunar surface.

The sun’s angle at the moon’s poles is steep, creating long shadows. This means that some of the polar craters receive no sunlight at all. When the water molecules happen to hop into one of those unlit areas, whose temperatures are among the coldest in the solar system at just tens of degrees above absolute zero, it drains their thermal energy and they remain stuck to the surface.

“So, over time, you could build up ice deposits in these permanently shadowed regions, which might be basically the only source of water on the entire moon in useful quantities,” Lewis said.

FOR MORE INFORMATION: https://phys.org/news/2022-06-nasa-mission-aims-ice-moon.html

VTerrestrial and marine habitats have been considered the ecosystems with the highest primary production on Earth by far. Microscopic algae in the upper layers of the oceans and plants on land bind atmospheric carbon (CO₂) and produce plant material driven by photosynthesis. Since sunlight does not penetrate into the subsurface, hardly any such primary production is to be expected.

However, genetic analyses of microorganisms in groundwater have indicated that even here many microorganisms are capable of primary production. In the absence of light, they must obtain the energy from oxidizing inorganic compounds, like from reduced sulfur of the surrounding rocks. However, the role of primary producers in the subsurface had never been confirmed before. 

Groundwater is one of our most important sources of clean drinking water. The groundwater environment of the carbonate aquifers alone, which is the focus of the study, provides about ten percent of the world’s drinking water. With this in mind, the researchers carried out measurements of microbial microorganism carbon fixation in a subsurface aquifer, 5 to 90 meters belowground.

Surprisingly high primary production rates in total darkness

“The rates we measured were much higher than we anticipated,” says the first author of the study Dr. Will Overholt, Postdoctoral Researcher at Friedrich Schiller University Jena. “They equal carbon fixation rates measured in nutrient-poor marine surface waters and are up to six-fold greater than those observed in the lower zones of the sunlit open ocean, where there is just enough light for photosynthesis”. 

Based on the measured carbon fixation rates, the researchers conservatively extrapolated global primary production in carbonate groundwater to be 110 million metric tons of carbon per year. Collectively, the net primary productivity of approximately 66 percent of the planet’s groundwater reservoirs would total 260 million metric tons of carbon per year, which is approximately 0.5 percent that of marine systems and 0.25 percent of global net primary production estimates.

“This may sound small but these measurements represent only our first estimate of what the true global value may be,” says senior author Prof Kirsten Küsel from the University of Jena and iDiv. “Since there is very little energy available in these nutrient-poor and permanently dark habitats, even a small percentage of the global primary production is a surprise.” 

The researchers also sought to identify the microorganisms responsible for fixing carbon and generating new biomass within the aquifer. Metagenomic analyses point to a highly abundant microorganism not closely related to previously studied bacteria, within an uncharacterized order of Nitrospiria. “As food, these organisms are thought to form the basis of life for the entire groundwater ecosystem with all of its thousands of microbial species, similar to the role algae play in the oceans or plants on land,” says Overholt.

Unique method to measure primary production of microorganisms in aquifers

Measuring carbon fixation can be done with radioactively labeled carbon dioxide. “In carbonate rock environments, there is abundant dissolved CO₂, that can make it difficult to directly observe rates of carbon fixation,” says Prof Susan Trumbore from the Max Planck Institute for Biogeochemistry in Jena. The team, therefore, used a special method to trace a small amount of labeled CO₂ using highly sensitive accelerator mass spectrometry. “It is exciting to see what new insights these methods can lead to,” she says.

“Our findings offer new insights into how these subsurface ecosystems function, giving clues on how to monitor or remediate groundwater sources,” says Kirsten Küsel.

The research was published in Nature Geoscience.

FOR MORE INFORMATION: https://phys.org/news/2022-06-life-earth-interior-productive-ocean.html

Poisonous algae blooms are becoming more common in the US, threatening water supplies and public health. But so far, there are few state or federal guidelines, and local water managers could use some help, a UConn-led team of researchers reports in the September 30 issue of Nature Sustainability.

A massive bloom of green-blue algae in Lake Erie in 2014 forced Toledo, Ohio to warn over half a million residents not to drink or even touch their tap water. It was one of the first times that algae bloomsmade national news, but it wouldn’t be the last. Since then, Salem, Oregon; Lake Hodges in California; and Lake Oneida in New York have had massive blooms. The toxins produced by such blooms can cause numbness, dizziness, convulsions, liver damage and even death.

“They’re nasty,” says Christine Kirchhoff, Associate Professor and Castleman Professor of Engineering Innovation in the Department of Civil & Environmental Engineering. Some of these toxins, such as liver-damaging microcystins and cylindrospermopsin, can be managed with combinations of chlorine and activated carbon. Other algae toxins like anatoxins and saxitoxins, which target the nervous system, are not easily removed by conventional water treatments. And you can’t boil them out of the water. So when a big algae bloom occurs in a reservoir, water managers can struggle to make sure the water is safe.

Kirchhoff and other researchers from UConn and the University of Michigan surveyed public water managers across the United States who manage systems that draw from inland lakes. Such lakes, even extremely large ones such as Lake Erie, are warming and may become more prone to algae blooms due to climate change.

More than half the water managers surveyed said their system had experienced a bloom of harmful algae at least once. Almost a third of the managers said they experienced them at least once a year, and 60% of those who’d had a bloom said they believed the problem was getting worse. Most water managers said they relied on their state agencies and professional associations for advice on how to handle harmful algae blooms in the water supply.

Unfortunately, a lot of state agencies don’t have that much to offer on the problem. States take their cues from the US Environmental Protection Agency (EPA), and currently EPA doesn’t regulate algae toxins under the Safe Drinking Water Act. Through the Unregulated Contaminant Monitoring Program, EPA did collect data from the treated water of a random sample of water systems across the US a few years ago, and the results showed limited occurrence of toxins in public water supplies.

Kirchhoff says the EPA survey aims to be nationally representative and so cannot rule out the potential for greater risk of toxic blooms at a state or regional level. The Connecticut Department of Public Health had a voluntary algae toxin testing program after the Toledo bloom raised concerns in the state. Systems that submitted voluntary samples for testing did not detect any toxins, and the testing program was discontinued.

Because cyanobacteria behavior is complex, monitoring for algal toxins is also complicated. Sometimes there is no visible bloom, but there are toxins present or there may be toxins in one part of a lake or at one depth and not elsewhere. For these reasons, “I would like to see a longer term, broader monitoring program that uses what we know now,” to determine areas at risk here in Connecticut and across the country, to better protect the public, Kirchhoff says.

FOR MORE INFORMATION: https://phys.org/news/2021-09-toxic-algae-blooms-worse-oversight.html

A study has pinpointed the likely source of most natural gas contamination in drinking-water wells associated with hydraulic fracturing, and it’s not the source many people may have feared.

What’s more, the problem may be fixable: improved construction standards for cement well linings and casings at hydraulic fracturingsites.

A team led by a researcher at The Ohio State University and composed of researchers at Duke, Stanford, Dartmouth, and the University of Rochester devised a new method of geochemical forensics to trace how methane migrates under the earth. The study identified eight clusters of contaminated drinking-water wells in Pennsylvania and Texas.

Most important among their findings, published this week in the Proceedings of the National Academy of Sciences, is that neither horizontal drilling nor hydraulic fracturing of shale deposits seems to have caused any of the natural gas contamination.

“There is no question that in many instances elevated levels of natural gas are naturally occurring, but in a subset of cases, there is also clear evidence that there were human causes for the contamination,” said study leader Thomas Darrah, assistant professor of earth sciences at Ohio State. “However our data suggests that where contamination occurs, it was caused by poor casing and cementing in the wells,” Darrah said.

In hydraulic fracturing, water is pumped underground to break up shale at a depth far below the water table, he explained. The long vertical pipes that carry the resulting gas upward are encircled in cement to keep the natural gas from leaking out along the well. The study suggests that natural gas that has leaked into aquifers is the result of failures in the cement used in the well.

“Many of the leaks probably occur when natural gas travels up the outside of the borehole, potentially even thousands of feet, and is released directly into drinking-water aquifers” said Robert Poreda, professor of geochemistry at the University of Rochester.

“These results appear to rule out the migration of methane up into drinking water aquifers from depth because of horizontal drilling or hydraulic fracturing, as some people feared,” said Avner Vengosh, professor of geochemistry and water quality at Duke.

“This is relatively good news because it means that most of the issues we have identified can potentially be avoided by future improvements in well integrity,” Darrah said.

“In some cases homeowner’s water has been harmed by drilling,” said Robert B. Jackson, professor of environmental and earth sciences at Stanford and Duke. “In Texas, we even saw two homes go from clean to contaminated after our sampling began.”

The method that the researchers used to track the source of methane contamination relies on the basic physics of the noble gases (which happen to leak out along with the methane). Noble gases such as helium and neon are so called because they don’t react much with other chemicals, although they mix with natural gas and can be transported with it.

That means that when they are released underground, they can flow long distances without getting waylaid by microbial activity or chemical reactions along the way. The only important variable is the atomic mass, which determines how the ratios of noble gases change as they tag along with migrating natural gas. These properties allow the researchers to determine the source of fugitive methane and the mechanism by which it was transported into drinking water aquifers.

The researchers were able to distinguish between the signatures of naturally occurring methane and stray gas contamination from shale gas drill sites overlying the Marcellus shale in Pennsylvania and the Barnett shale in Texas.

The researchers sampled water from the sites in 2012 and 2013. Sampling sites included wells where contamination had been debated previously; wells known to have naturally high level of methane and salts, which tend to co-occur in areas overlying shale gas deposits; and wells located both within and beyond a one-kilometer distance from drill sites.

As hydraulic fracturing starts to develop around the globe, including countries South Africa, Argentina, China, Poland, Scotland, and Ireland, Darrah and his colleagues are continuing their work in the United States and internationally. And, since the method that the researchers employed relies on the basic physics of the noble gases, it can be employed anywhere. Their hope is that their findings can help highlight the necessity to improve well integrity.

FOR MORE INFORMATION: https://phys.org/news/2014-09-gas-leaks-faulty-wells-linked.html

With increased drought coverage from newspapers, water conservation increased in the San Francisco Bay Area during the drought that ended in 2016. That’s according to a new study from Stanford researchers that links real water consumption data with the public attention garnered by California’s recent droughts.

“A number of waterutilities that we work with observed unprecedented and unexpected water conservation levels during the recent drought in California compared to previous ones,” said hydrologist Newsha Ajami, who directs Urban Water Policy and Innovation research for Stanford’s Water in the West program. “We were curious to see what was prompting this level of public response, especially before the 2015 conservation mandate went into effect.” Ajami wondered if the heightened news coverage of the most recent drought might explain some of this behavior.

In an attempt to answer those questions, graduate student Kim Quesnel worked with Ajami to develop models examining conservation in different water districts throughout the Bay Area. She also worked with a team to develop a search algorithm to quantify drought coverage by state and national news outlets. The group’s results, published Oct. 25 in the journal Science Advances, show the relationship between media coverage and water savings, in some cases at the level of household smart meters.

In California, water has long been a vital political and practical problem. California’s vast agriculture industry requires irrigation for crops and drinking water for livestock; at the same time, growing cities need water for drinking, washing, and landscaping. Results from this study could help the state realize the importance of encouraging water efficiency and conservation.

The power of online tools

The research team created a novel web-scraping and search algorithm, nicknamed Articulate, to quantify the drought-related coverage from nine major national and California-based newspapers between 2005 and 2015. This period encompassed the majority of the two most recent California droughts in 2007-2009 and 2011-2016. They compared their algorithm’s results with Google Trends, a free online tool that showed the number of drought-related searches performed by Bay Area residents. The level of media attention to drought conditions closely matched the fluctuations in the public’s awareness and curiosity.

The first drought period saw barely any publicity or increased web searches. “There were other things on people’s minds,” said Quesnel, referring to a historic election season and the Great Recession, both of which dominated media coverage at the time. The second drought, however, generated hundreds of news articles per month describing dry conditions, historic mandatory water conservation measures and rising water prices statewide.

Quesnel compared the water demands of single-family households in the Bay Area to factors including unemployment, weather, household income and, of course, media coverage. From her models, she found that economic hardship from the high unemployment rates during the Great Recession correlated with water savings during the first drought. In both droughts, higher summer temperatures corresponded to higher seasonal water use. Strikingly, their models also found that for every 100-article increase over a two-month period, there was an 11 percent to 18 percent decrease in demand for water. With an enormous spike in media attention during the second drought, water savings across all studied areas were dramatic.

Web portal

The question for the team was whether these changes would last.

“In arid and semi-arid places like California, over half of the water use in single-family homes is outdoors, for landscaping, so a lot of this change could have been due to households choosing to not water their lawns a few times per week, for example, or to more permanent changes such as residents removing their lawns completely,” Quesnel said.

“Some of the short-term water saving behaviors prompted by the drought might just vanish,” said Ajami, who is also a senior research scientist with the Stanford Woods Institute for the Environment.

Their group recently created a web portal that allows people to interact with drought data, watching district-level water usage in addition to tracking drought-related media and public interest. Since the time period studied in this paper, the drought has been declared over. Longer-term changes like replaced appliances, drought-tolerant landscaping and gray water systems remain, but mandatory water restrictions have been rescinded, media coverage has declined and water use has rebounded in many of the areas studied.

Despite the rebound, Ajami said this research suggests people do respond to information in the media. “If you provide the right set of knowledge and information to consumers, they do actually react and respond to that message. The drought really raised the profile of water issues faced by the state, an invaluable outcome,” Ajami said.

FOR MORE INFORMATION: https://phys.org/news/2017-10-link-media-attention-drought-household.html