GET WET!

Even as worsening drought and aridification force Los Angeles to end its overwhelming dependence on imported water, Angelenos may soon realize that weaning themselves off supplies from the rugged eastern Sierra Nevada doesn’t mean they will stop paying for the city’s long, complicated history there.

That’s because, even if the city is able to make good on a pledge by Mayor Eric Garcetti to recycle 100% of its water by 2035 and increase its ability to capture storm water, Los Angeles will still have to pay millions of dollars to control the region’s hazardous dust pollution—an environmental consequence of L.A.’s draining of Owens Lake more than a century ago, as well as recent diversions that have lowered the level of Mono Lake farther north.

Recently, the Los Angeles Department of Water and Power accused Owens Valley air pollution authorities of “regulatory overreach” when they fined the utility $21 million for ignoring an order to control dust on a 5-acre patch of dry lake bed. The order and subsequent fine imposed by the Great Basin Unified Air Pollution Control District was an attempt to “squeeze” cash from the city’s water users, the DWP said.

“Enough is enough,” read a statement from Cynthia McClain-Hill, president of the Los Angeles Board of Water and Power Commissioners. “More than 20 percent of our ratepayers live below the poverty line, and we cannot allow the people of Los Angeles to serve as a blank check for Great Basin’s illegal orders.”

The agency also angered Mono Lake officials and conservationists recently when it signaled to the Los Angeles City Council that it wanted to scrap portions of a 1994 agreement that aims to control dust emissions at Mono Lake, the hyper-saline water body east of Yosemite National Park famous for its craggy tufa formations.

Arguing that climate change and drought have fundamentally altered the state’s water supply, DWP officials suggested that it was impossible for them to ensure Mono Lake remained at certain dust-damping levels.

To be sure, DWP ratepayers will see increases due to the cost of transforming the city’s water infrastructure. However, officials say the demands by Great Basin will add even more to their water bills.

For their part, Owens Valley officials accuse Los Angeles of trying to avoid responsibility for the environmental damage its water use has caused.

“The city wants to undermine our authority to protect people’s health and safety by ordering dust control measures where needed,” said Phil Kiddoo, the air district’s enforcement officer. That enforcement authority is granted under a 2014 agreement between the DWP and the air district, he said.

The water diversions that began in 1913 dried up the 110-square-mile Owens Lake, triggering immense sheets of powder-fine, lung-damaging particles that descended on towns downwind. Over the last three decades, the DWP has spent more than $2.5 billion on projects that have reduced dust emissions by nearly 100%.

“Despite this achievement, Great Basin has refused to acknowledge the success of the program, and instead has issued a series of orders and associated fines that demonstrate a clear pattern of overreach of its regulatory role,” read a DWP statement.

For the first 90 years of its existence, the Los Angeles Aqueduct met more than 60% of the city’s demands. Today, however, half of that water must be directed onto Inyo County ranch lease operations, fisheries and dozens of court-stipulated mitigation projects to meet federal air pollution standards.

In a lawsuit filed in Sacramento County Superior Court—where the 2014 agreement was entered—air district officials allege that the DWP’s refusal to control dust emissions on the 5-acre area is a violation of the pact.

Under an earlier agreement, the DWP must fund 85% of Great Basin’s annual operating budget—about $7 million—and pay for all district legal fees whether it wins or loses in court.

The DWP has responded by filing its own lawsuit in Los Angeles County Superior Court, accusing the air district of exceeding its authority and ordering dust control measures without first conducting an environmental analysis of its impacts, as required by the California Environmental Quality Act.

“This 5-acre project may seem small—but it would result in a huge hit for our ratepayers,” said Marty Adams, general manager and chief engineer of the DWP. “It would add about $2 onto their monthly water bills. And for what? A pet project the district cooked up that doesn’t meet regulatory requirements.”

Adams said that there was “no end in sight” for such demands. “We hope it doesn’t blow up the 2014 agreement.”

Not only does the DWP accuse Great Basin of overstepping its authority, officials argue that the work would need the approval of five Indigenous tribes that have nominated 186 square miles of the lake bed for listing in the California Register of Historical Resources and in the National Register of Historic Places.

One of those tribes, the Fort Independence Indian Community of Paiute Indians, has not yet said whether it sanctions the project.

“We are shocked to see Great Basin attempting to mandate that LADWP act in opposition to the requests of our tribal partners,” read a statement from Paul Liu, manager of the utility’s Owens Lake Dust Mitigation Program.

Great Basin argues that the mitigation area is not on tribal land. The agency says it is held in trust by the State Lands Commission, which supports the implementation of air pollution controls.

The dispute underscores the acrimony that has seethed in Owens Valley since the early 1900s, when the city had agents pose as farmers and ranchers to buy land and water rights in the valley, then began building an aqueduct to collect and divert water from Inyo County to the water-craving metropolis to the south.

“The LADWP is always looking for an excuse to avoid doing the right thing for the people of Owens Valley,” said Michael Prather, a botanist and longtime Sierra Club activist in the community of Lone Pine. “In the meantime, we breathe toxic dust while people in Los Angeles build more golf courses and swimming pools with our water.”

The air pollution generated by the 5-acre area in dispute “can be severe,” according to the district’s lawsuit.

Particulate-matter air pollution can remain airborne for long periods and can lodge deep in the lungs and cause scarring, respiratory illnesses, cardiovascular disease, as well as more frequent attacks of asthma in children.

The hazardous effects of so-called PM10—particles that are less than 10 micrometers in diameter, far smaller than the width of a human hair—extend to large areas downwind of Inyo County, district officials say, including the city of Ridgecrest and the Naval Air Weapons Station China Lake.

“Based upon data from this area collected on April 16, 2018,” the district’s lawsuit says, “PM10 emissions were 160 percent of the federal standard of 150 micrograms per cubic meter.” That air pollution was transported to the community of Lone Pine, about nine miles downwind, it says.

Under the 2014 agreement, the city agreed to comply with district orders to implement controls on 48.6 square miles of the lake bed, and up to 4.8 additional square miles, if needed. It provided a cap on the total area that could be ordered for dust control by the district in return for the city’s agreement not to challenge those orders.

But the agreement did not settle the matter in the heavily litigated region where old-timers recall that each of the last four mayors of Los Angeles, in turn, proclaimed, “The bad old days are over in Inyo County.”

Then there was a DWP manager who bragged, “Litigation is cheaper than water.”

The agreement allows use of shallow flooding, managed vegetation, gravel and tillage to contain and prevent dust emissions.

The project in question was designed to minimize ground disturbance and encourage growth of existing shrubs through seasonal watering. A 1,000-foot-long water line laid on top of the ground would feed three hose spigots to allow tribal members to water the vegetation. The water would be supplied by a DWP water trailer parked nearby.

The DWP doubts the effectiveness of the plan.

“It is not a tested dust control method,” said Joseph Ramallo, the utility’s assistant general manager of water and power. “We have no evidence to prove that it will work to control dust or protect cultural resources, meaning any expenditure could be a complete waste of our customers’ money.”

However, at least one supporter said it would be the least intrusive dust control measure employed to date.

Kathy Bancroft of the Lone Pine Paiute-Shoshone Indian Reservation gazed across the vast patchwork of dust control measures blanketing the lake bed recently and shook her head. “Just look at how Los Angeles ruined this landscape,” she said.

“The dust mitigation project everyone is fighting over in court would not require excavation. It would be watered by hand without disturbing the soil or the artifacts buried in it,” she said. “All L.A. has to do is provide a little water. Is that too much to ask?”

FOR MORE INFORMATION: https://phys.org/news/2022-11-legacy-owens-valley-air-pollution.html

Phosphorus is an important raw material, especially as a fertilizer for agriculture. But in water bodies, it deteriorates the water quality. Since the 1980s, phosphate precipitation has therefore been one of the core processes in municipal wastewater treatment plants. Phosphorus is bound with salts in the sewage sludge. However, because this raw material is also becoming increasingly scarce, it should be recovered there. This can be achieved, for example, if it is present in bound form as vivianite. Researchers from the Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB) have investigated which factors promote the formation of vivianite and thus increase the amount of recoverable phosphorus.

There are many good reasons to recycle phosphorus: Rock phosphates are increasingly contaminated and supply depends on a few countries. That’s why it has been on the European Union’s list of “critical raw materials” since 2014. And the German government also passed the Sewage Sludge Ordinance in 2017: According to it, by 2032, larger plant operators are to ensure that the phosphorus contained in sewage sludge is recovered.

Precipitation in sewage sludge can produce vivianite—an iron-phosphorus compound from which phosphorus can be relatively easily recycled. “But until now, it wasn’t clear what conditions in sewage treatment plants favor vivianite formation. We are also interested in this for lake restoration, where precipitation of phosphorus from water is also used to reduce nutrient loads and thus improve water quality,” explained IGB researcher Michael Hupfer, who led the study. The team analyzed the properties and compositions of sludge samples from 16 wastewater treatment plants, as well as the plants’ process parameters, to determine the factors influencing vivianite formation.

High iron content favors vivianite formation—high sulfur content reduces it

High iron content proved to be the most important factor in favoring vivianite formation. High sulfur content, in turn, decreased vivianite formation. “There are sulfur-containing and sulfur-free precipitants. We were able to show by comparison that the use of sulfur-containing precipitants can increase the sulfur content in the sludge and thus counteract vivianite formation. The choice of precipitant can therefore have a significant influence on phosphorus recycling,” said IGB doctoral student Lena Heinrich, lead author of the study.

Adjusting the conditions can make a difference: In the 16 wastewater treatment plants, the proportion of phosphorus bound in vivianite varied from around 10% to as much as 50%. This range shows the great potential to increase the yield of vivianite. 

“For us as aquatic ecologists, the findings are very important because iron-containing precipitants can also be considered for restoration of lakes that are eutrophic, or polluted with nutrients. The efficiency of an iron salt addition is much greater if it results in the formation of stable vivianite in the sediment, which is then—perhaps one day—also available for the recovery of phosphorus,” said Hupfer.

FOR MORE INFORMATION: https://phys.org/news/2022-10-phosphorus-recycling-sewage-sludge.html

Oil and gas is required for many of life’s everyday functions. Cars, trains and planes all rely on fuel in order to move people around, leaving many dependent on them. Many also rely on gas and fuel to keep their homes warm during the winter.

Although there are renewable energy sources like solar panels and windmills as well as transportation alternatives like electric vehicles, the economy is still “hooked” on oil.

There are, however, many concerns about the negative environmental impact of the oil industry and its contribution to climate change. To better understand the impact of oil and gas on the environment, and even the health of individuals, it’s important to know where oil and gas come from and what fracking is.

What is fracking?

Fracking is a method used to extract natural gas and oil from deep within the Earth’s surface, according to National Geographic. During the process of fracking, chemicals, water and sand are injected at a high pressure to open and widen cracks below the surface of the Earth.

There are many areas in the United States where fracking takes place including in the Marcellus shale formation in the northern Appalachian Basin. This includes areas in New York, Pennsylvania, Maryland, Ohio, Virginia and West Virginia, according to National Geographic.

What is hydraulic fracking?

Hydraulic fracturing is what is commonly referred to as fracking. The Barnett shale formation in northern Texas was one of the first places to use hydraulic fracturing technology, according to National Geographic.

What is crude oil?

According to Investopedia, crude oil is a fossil fuel made up of organic materials and hydrocarbon deposits. A petroleum product, crude oil is often refined to create diesel and gasoline.

What is natural gas?

Natural gas is a fossil fuel made up of many different compounds, with the largest compound being methane. Found deep under the Earth’s surface, natural gas is used as a fuel, according to the U.S. Energy Information Administration.

What are the negative effects of fracking?

There are many negative effects associated with fracking, both health-wise and environmentally.

According to the Natural Resources Defense Council, because of the toxic air pollution resulting from fracking, health effects include childhood leukemia, cardiac problems, asthma symptoms, birth defects and headaches. Some of the over 1,000 harmful chemicals used in fracking have even been linked to cancer.

There are no federal requirements for drillers to disclose what chemicals they use, meaning that people often do not know what is being pumped into their communities. State laws are also poorly enforced and there is limited testing data on air and water quality, according to the NRDC.

Because of the many unknowns, nurses and doctors often have difficulty determining what chemicals a patient has been exposed to, the Natural Resources Defense Council says.

Fracking has also been linked to a loss of plant and animal species due to greenhouse gasses, toxic air pollutants, water waste and noise, according to Yale University. Fracking is also sometimes linked problems in communities with fewer resources, worsening their burden.

The Independent Petroleum Association of America on its website contends fracking “has improved public health by dramatically improving air quality in recent years. This is not to say there are no risks, but the full body of research on this issue shows that those risks are manageable.”

The IPAA also says some states have “found that emissions during oil and natural gas development do not exceed public health thresholds.” The association also says “two dozen scientific studies have concluded that fracking does not pose a major threat to groundwater.”

FOR MORE INFORMATION: https://phys.org/news/2022-10-fracking-key-terms-negative-effects.html

Shallow lakes and ditches emit less greenhouse gases if rooted submerged plants are predominant instead of free-floating plants or algae. There are several reasons why Dutch water managers should encourage more submerged plants in Dutch waterways, researchers argue. But these plants will have a better chance of survival if fewer fertilizers are leached into Dutch waters. The researchers recently published their findings in the journal Water Research.

Lakes and ditches cause a large share of the total emissions of methane, a greenhouse gas, in the Netherlands (estimated to be around 16%). Unfortunately, climate change amplifies this problem, because emissions of methane increase rapidly as water warms up. This happens especially in nutrient-rich water, where a lot of organic matter is present on the bottom that microorganisms convert into methane via the process of decay.

Free-floating aquatic plants (such as duckweed) and algae benefit the most from climate change, because they grow near the surface and so are the first to take advantage of the higher temperatures and higher CO₂ concentrations in the air. Meanwhile, the increasingly heavy rainfall is causing even more fertilizer to leach from farmland into the surface water.

More oxygen

However, in water where submerged plants predominate rather than free-floating plants, emissions increase much more slowly as the water warms up, researchers from Radboud University, the Netherlands Institute of Ecology (NIOO-KNAW), Wageningen University and IGB Berlin have revealed. They made their discovery by simulating Dutch waters in large tanks containing either mainly algae, free-floating plants or submerged plants. Half of the tanks were warmed by 4 °C, anticipating the expected degree of climate warming by the end of this century.

“We think submerged plants cause this effect because they leak oxygen into the soil, enabling the microorganisms there to consume more methane,” explains first author Ralf Aben of Radboud University. “There is a caveat though: we used the common plant watermilfoil. It is not clear whether all submerged plants have the same effect. That will require further research.”

Win-win situation

The discovery is good news for Dutch water managers, says final author Sarian Kosten of Radboud University. They are already investing in increasing the coverage of submerged plants in Dutch lakes and ditches, mainly to improve the water quality and biodiversity. “But this research shows that it is also good for reducing greenhouse gas emissions from bodies of water. So it’s a win-win,” continues Kosten.

“Unfortunately, too much fertilizer is still leaching into our surface water in everyday practice. This is due to the gigantic network of ditches we have in the Netherlands,” Kosten explains. “As a result, free-floating plants, which grow well in such waters, remain dominant. So, if we can reduce the amount of fertilizer, this will not only reduce nitrogen emissions, but it will also reduce greenhouse gas emissions from lakes and ditches.”

FOR MORE INFORMATION: https://phys.org/news/2022-10-submerged-greenhouse-gas-emissions-shallow.html

Certain invasive, non-native species can disrupt lakes to the point of rapid ecosystem collapse, contaminating water for drinking, aquaculture and recreation, a new study has found.

Human activity and climate change are causing invasive non-native species to spread rapidly across the globe. Researchers have found that certain invasive species can push lake ecosystems beyond a critical ‘tipping point’, causing a sudden shift from healthy to degraded conditions that is difficult to reverse.

Invasive fish such as Asian silver carp Hypophthalmichthys molitrix, and crustaceans such as American signal crayfish Pacifastacus leniusculus, were found to significantly reduce the abundance of other important organisms in lakes and degrade water quality. The findings, published today in the journal Global Change Biology, also provide guidance on the best ways to manage waterbodies.

Shallow lakes naturally exist in one of two alternative stable states: either healthy—with clear water with an abundance of vegetation, or degraded—with cloudy water dominated by algae. When a lake is in the latter state, algae use up all the nutrients in the water and block sunlight, preventing the growth of aquatic vegetation that would aid ecosystem recovery.

Deteriorated, algae-dominated freshwater ecosystems also threaten the health and water security of human populations. Blooms of cyanobacteria, known as ‘blue-green algae‘ can produce toxins that contaminate food webs and poison water supplies.

“Algal blooms represent one of the most significant threats to the security of the Earth’s surface freshwaters. Simply undoing the circumstances that triggered a tipping point will not restore the ecosystem—the road to recovery is slow and steep,” said Dr. Sam Reynolds in the University of Cambridge’s Department of Zoology, first author of the report.

However, although invasive species are recognized as a significant threat to global biodiversity, their impacts on ecosystem services may not be uniformly negative. Invasive molluscs, including the zebra mussel Dreissena polymorpha, were found to engineer the opposite biological and environmental response: they delay ecosystem collapse and potentially aid the recovery of degraded lake ecosystems. 

“Managers of drinking water reservoirs, for example, may be able to avoid the cost of dealing with blooms of harmful algae, by removing invasive crayfish but allowing established non-native zebra mussels to remain and act as biological filters,” said Professor David Aldridge, senior author of the report.

He added: “Early detection and rapid response plans should always be our first line of attack. But in situations where invaders have already established and can no longer be eradicated, it may be appropriate to embrace their positive effects.”

The researchers focused on shallow lake ecosystems, but say that their framework could be applied to other critical ecosystems that experience catastrophic tipping points—such as coral reefs, kelp forests and desert shrublands.

FOR MORE INFORMATION: https://phys.org/news/2021-10-crayfish-carp-invasive-species-lakes.html

EPFL scientists have studied two mechanisms that can help bring oxygen to the depths of a lake—essential for preserving the lake’s ecosystem. The classical deepwater renewal caused by surface cooling during winter is becoming less efficient due to climate change, especially in deep lakes.

Lakes need to contain a certain level of dissolved oxygen to maintain water qualityand preserve their ecosystems. While the upper layers of a lakeare typically rich in oxygen, that’s not the case for deeper layers; in most lakes, oxygenation of these layers occurs primarily through a process called convective cooling that takes place during the cooler autumn and winter periods. For deep lakes in temperate climates, like Lake Geneva, winters are often not cold enough for this process to occur on an adequate scale, meaning the very deep waters are not affected. The last full-depth convective cooling in Lake Geneva took place in 2012 during a severe cold spell (CIPEL).

Understanding other deepwater renewal mechanisms

“With climate change, there are more and more winters when the conditions needed for this process are not met,” says Rafael Reiss, a recent Ph.D. graduate at EPFL’s Ecological Engineering Laboratory (ECOL). “So we need to understand other mechanisms that could enable the oxygenation of a lake’s deeper layers.” He studied two alternative deepwater renewal mechanisms as part of his Ph.D. thesis, both of which are induced by wind: interbasin exchange, where water is exchanged between the shallow Petit Lac and the deeper Grand Lac basin, and coastal upwelling. “Unlike convective cooling that’s triggered by cold air temperatures, the mechanisms we studied are less sensitive to climate change because they are wind-driven. They occur in Lake Geneva several times each winter and could therefore play an increasingly important role in renewing and aerating the deeper layers,” says Reiss.

Water in these deep layers is usually cold, oxygen-poor and nutrient-rich. The upper layers, on the other hand, are warmer with higher concentrations of oxygen and lower concentrations of nutrients. The two layers barely mix for most of the year due to their different densities—warm water is less dense than cold water, leading to a so-called stable stratification. But once the air temperature drops during autumn and winter, the surface waters cool and the stable stratification is gradually eroded from the top downwards. If the winter is cold enough, the waters near the surface reach the same temperature, and consequently the same density, as the deeper waters. The result is a complete overturning of the water column, whereby oxygen from the upper layers is brought to the bottom and nutrients from the lower layers rise to the surface.

Deepwater renewal several times a winter

Reiss’ study showed that, under the effect of the earth’s rotation, the strong winter winds that frequently blow across Lake Geneva from the southwest push coastal waters at the northern shore of the Grand Lac towards the center of the lake, with these waters being replaced by the rising of deeper waters. The same winds push the surface waters of the Petit Lac towards the Grand Lac, causing deeper waters from the Grand Lac to take their place. These two complex exchange mechanisms cause the oxygen-poor, nutrient-rich lower layers to rise upwards, sometimes from depths of over 200 meters (Lake Geneva has a maximum depth of 309 meters). These upwelled, deep waters can remain close to the surface for several days (or even reach the surface) before descending back to great depths, allowing them to be enriched with oxygen through exchange with the upper layers and the atmosphere.

To carry out this study, Reiss and his team first spent two winters collecting data in the field, measuring current velocities and water temperatures. They then employed a 3D hydrodynamic model and combined it with a modeling technique called particle tracking in order to analyze the pathways of the upwelling waters in great detail. “Our findings show just how complex these mechanisms are,” says Reiss. “They take place in 3D, meaning they can’t be described using the one-dimensional models that are frequently used to predict the impact of climate change on lakes. These mechanisms deserve further attention when assessing deepwater renewal in large, deep lakes.”

FOR MORE INFORMATION: https://phys.org/news/2021-09-deepwater-renewal-lake-geneva-climate.html

In a sign of progress in the Orange County oil spill, Huntington Beach city and state beaches reopened Monday morning as cleanup crews continued their work combing the shores for vestiges of oil and tar.

As of Sunday, officials said 5,400 gallons of oil have been collected from vessels and 250,000 pounds of oil debris have been cleaned from beaches and other areas.

The reopening comes after water-quality test results showed nondetectable amounts of oil toxins in the water, city officialssaid.

“We understand the significance our beaches have on tourism, our economy and our overall livelihood here in Huntington Beach,” Mayor Kim Carr said in a statement. “It is important that our decision to reopen our shoreline and water be based on data and that we continue to monitor the water quality going forward.”

In the first few days after the spill, officials warned that up to 144,000 gallons of crude may have seeped out of the pipeline, which runs from a processing and production platform called Elly off the shore in Huntington Beach to the Port of Long Beach.

But later in the week, a U.S. Coast Guard official said the spill was probably smaller than initially projected, downgrading the leak to between 24,696 gallons and 131,000 gallons.

Authorities believe that a ship’s anchor scraped the pipeline and dragged it across the ocean floor.

The Coast Guard said Friday that the anchor strike probably occurred months ago, and possibly as long as a year ago. A slight crack in the pipeline may have grown worse over time, or may have survived the first strike intact but suffered damage in another incident, officials said.

FOR MORE INFORMATION: https://phys.org/news/2021-10-crews-pounds-oil-debris-orange.html

It is a common perception that waters close to population would be more polluted than those offshore or at higher latitudes.  However, researchers from The Hong Kong University of Science and Technology (HKUST) found that the ratio between two common microalgae diatom and dinoflagellate (dino) – a common benchmark of water quality, has been nearly doubled in the Pearl River Estuary (PRE), one of the world’s most urbanized subtropical coastal waters, over the past two decades. 

Usually, the higher the Diatom/Dino ratio is, the healthier the water quality is supposed to be.  However, according to Prof. Liu Hongbin, Associate Head and Chair Professor of HKUST’s Department of Ocean Science who led the research, it is not conclusive whether this finding indicates an improved water quality at PRE, as the team discovered that temperature as well as the level of nutrient concentration in the ocean also took a toll to the algae population. 

Algae, or phytoplankton, is important to the marine ecosystem as they not only help covert carbon dioxide into organic matter and oxygen, but is also a key food source to a wide array of sea creatures.  In Hong Kong waters, diatom and dino are the two main types of algae which together made up about 80 per cent of the entire algae population.  While diatom has long been considered the ‘good algae’ as they usually grow in less polluted water, dino is the evil brother as its toxicity can kill fish and cause hypoxia in coastal waters.  The Diatom/ Dino ratio has long been used as a benchmark to indicate the optimal level of a marine ecosystem. Theoretically, the more the proportion of diatom, the better the water quality. 

Now, a research team led by Prof Liu, which analyzed a plethora of data ranging from temperature, nutrient concentration to oxygen levels of the PRE during the 18 years to 2017, has observed a growing diatom dominance, or an increase in the Diatom/Dino ratio since 2000.  

However, using a combination of multiple data-driven statistical models, the team found that the abundance of diatom may not be a result of water quality improvement, but a change of nutrient composition in the PRE—in particular a rapid increase of nitrate against a relatively constant level of ammonium and phosphate arising from the increasing anthropogenic input.  Moreover, the team also found that the abundances of both diatom and dino were positively correlated with temperature, they predicted that for every rise of 1 to 4°C in temperature, the Diatom/Dino ratio could surge by up to 12% under the same nutrient content.  

While there had been many studies on the phytoplankton abundance in higher latitudes or offshore waters, few research were done on highly urbanized subtropical or tropical coastal waters like those of the PRE.  

Prof. Liu said, “Algae bloom is a major environmental problem, our model sheds light on prediction and even prevention of future blooms.  Meanwhile, some studies suggest that not all diatoms species are angels, some from the Pseudo-nitzschia genus—for example, may produce an acid that is detrimental to the neural system of marine mammal and birds.  Going forward, we will also study the ecological sequences of diatom blooms, as well as the abundance and physiology of those toxic diatoms.” 

The findings were recently published in the scientific journal Global Change Biology.

FOR MORE INFORMATION: https://phys.org/news/2021-10-dominance-diatom-algae-pearl-river.html

Coastal wetlands support diverse and vital ecosystems central to coastal areas’ biodiversity and economic vitality. However, coastal wetlands are threatened by sea level rise that can lead to flooding and land use changes that alter the way people can live or work in these areas. These impacts are large. Approximately 600 million people live less than 10 meters, approximately 33 feet, above sea level, while 2.4 billion people live within 100 km, or around 60 miles, of the coast.

An international, interdisciplinary research team led by University of Oklahoma professor Xiangming Xiao is using satellite imagesto measure the changes of coastal wetlands in China from the early 1980s to the present. The research team is also assessing the effects of conservation efforts on preserving and recovering these important ecosystems. Their findings on China’s coastal wetlands are now published in the journal, Nature Sustainability.

Xiao is a George Lynn Cross Research Professor in the Department of Microbiology and Plant Biology, Dodge Family College of Arts and Sciences, and the director of the Center for Earth Observation and Modeling at OU. Xinxing Wang, a graduate student at Fudan University in China, is the first author of the paper.

Since the 1980s, the coastal zone of China has experienced increased urbanization, industrialization and population growth, combined with increased sea level rise, that has led to significant decreases of wetland areas.

“Because coastal wetlands provide diverse important ecosystem goods and services, their loss has reduced biodiversity, affecting water quality, carbon storage and coastal protection from storm events and increased regional vulnerability to sea level rise which, together, pose threats to human health and coastal sustainability,” Xiao explained.”We wanted to know how these coastal zones have changed over recent decades, which had been very difficult to do,” he said. “However, in the past 10 years or so, cloud computing facilities like Google Earth Engine have become available, and a lot of satellite imagery has become freely available, so the technology has come to the point where we can track, at a high spatial resolution, coastal zone changes over time and space.”

The researchers analyzed more than 62,000 satellite images of coastal wetlands in China taken between 1984 to 2018. They generated two three-year maps (1985-88 and 1988-91) and 29 annual maps of coastal wetlands for the period 1990 to 2018, for a total of 31 maps. They also identified and mapped three types of coastal wetland areas, tidal flats, saltmarshes and mangroves.

They were interested in seeing whether these images could show the impact of China’s development and enforcement of environmental laws and regulations on mitigating the loss of wetland areas. They found that wetland areas significantly decreased during 1984 through 2011. However, following increased conservation and restoration efforts under China’s drive for sustainable development and ecological civilization, the outlook improves.

“We found a substantial increase in saltmarsh area and a stable trend of tidal flat areas after 2012, driven by decreased anthropogenic activities (pollution) and increased conservation and restoration efforts,” said Xiao.

“To achieve the sustainability of coastal wetlands, China must continue to give top priority to conservation and the restoration of coastal wetlands and their ecosystem services,” he added. “Our satellite-based mapping tools and resultant maps of coastal wetlands at high spatial resolution (30-m) are important in assessing, monitoring, reporting and verifying future changes in the coastal wetlands of China and the world.”

FOR MORE INFORMATION: https://phys.org/news/2021-10-satellite-images-positive-impact-efforts.html

A new modeling capability developed at Oak Ridge National Laboratory incorporates important biogeochemical processes happening in river corridors for a clearer understanding of how water quality will be impacted by climate change, land use and population growth.

Researchers used high-performance computing and the award-winning Amanzi-ATS software to include biogeochemical reactions in microbially active zones near streams in models that track the movement of dissolved chemicals in river networks. These reactions have a major influence on the cycling of carbon, nutrients and contaminants at basin scales. The new multiscale model better tracks water quality indicators such as nitrogen and mercury levels. 

“To build a next-generation modeling capability to address water quality issues, we needed a new multiscale framework that allows us to incorporate fundamental understanding of key processes and how those fine-scale processes manifest at much larger scales,” ORNL’s Scott Painter said.

The research team validated and demonstrated the model on several watersheds.

FOR MORE INFORMATION: https://phys.org/news/2021-11-quality-biogeochemical.html