Many city surfaces are coated with a layer of soot, pollutants, metals, organic compounds and other molecules known as “urban grime.” Chemical reactions that occur in this complex milieu can affect air and water quality. Now, researchers reporting in ACS Earth and Space Chemistry have taken a closer look at urban grime collected from two U.S. cities, revealing for the first time that the material absorbs sunlight and therefore might participate in photochemical reactions.
Scientists have previously analyzed lab-prepared urban grime, as well as samples collected from cities, but they still don’t have a complete understanding of what’s in the material, or how it varies by location. Some components can react with other molecules in the grime or air, which could affect what gets released into the atmosphere or into the water when it rains. To better understand these processes, Tara Kahan and colleagues wanted to investigate the physical properties, light absorption and composition of urban grime samples collected from Syracuse, New York, and Scranton, Pennsylvania.
The researchers collected samples of urban grime from Syracuse by placing vertical quartz plates outdoors for 30 days and then analyzed the surfaces. Although urban grime was long thought to be predominantly a film, the samples showed collections of particles, rather than a uniform film, consistent with evidence from other recent studies. In different experiments, the team scraped grime from wet exterior surfaces of windows in both cities and analyzed their compositions. The results were similar to those reported from other cities in Canada and Europe, but there were differences in specific ions. For example, higher chloride levels were found in North American cities, which could be from the use of road salt in the winter, whereas higher sulfate levels were reported in some European cities, likely because of coal combustion. The team also observed that urban grime absorbed light at wavelengths found in sunlight, which suggests that the sun could speed up or slow down chemical reactions that affect air and water quality in cities.make a difference: sponsored opportunity
Corey R. Kroptavich, Shan Zhou, Shawn F. Kowal, Tara F. Kahan. Physical and Chemical Characterization of Urban Grime Sampled from Two Cities. ACS Earth and Space Chemistry, 2020; DOI: 10.1021/acsearthspacechem.0c00192
FOR MORE INFORMATION: American Chemical Society. “How urban grime affects chemical reactions in cities.” ScienceDaily. ScienceDaily, 30 September 2020. <www.sciencedaily.com/releases/2020/09/200930144428.htm>.
New research from the FAMU-FSU College of Engineering combines climate and land use projections to predict water availability, information that is crucial for the preparations of resource managers and land-use planners.
“This research presented a new method that can be used to generate future climate data for the existing hydrological models,” said Gang Chen, a professor of civil and environmental engineering at the college. “With the integration of more reliable future climate data, the existing hydrological models can more accurately project future water scenarios in the face of climate change.”
Chen is leading a team of experts to produce new data techniques to improve hydrological modeling that is essential for water resource management planning. Their work was published in WATER.
The researchers used their method to examine the hydrological processes in Alabama’s Upper Choctawhatchee River Watershed, which eventually flows into Florida and empties into the Choctawhatchee Bay. They integrated land use projections with future climate data to study the combined effects on the hydrological response of the watershed.
“Using water balance simulations, we discovered that surface runoff and evapotranspiration are dominant pathways for water loss in the Southeast,” Chen said.
Yashar Makhtoumi, a doctoral candidate in the Department of Civil and Environmental Engineering, is working with Chen on new data downscaling techniques. The innovative process provides more data and improves modeling outcomes.
“Few research projects have been done to investigate the combined effects of land use change and climate change using projections,” Makhtoumi said.
The results of the study showed the effects on water resource variables were seasonal. Surface runoff caused the most significant changes in various simulations, and evapotranspiration was also an issue, though to a lesser degree. The models indicate that by midcentury, more frequent extremes in water balance are projected to be an issue.
Although the research focuses on a single watershed, the researchers believe their work could be applicable on a wider scale. That’s important for a state like Florida, where population growth, development and climate change are forcing residents and planners to realize the limitations of the state’s water supply.
“Our model demonstrated that it could capture hydrologic parameters accurately and could be used for future studies of water quality,” Chen said. “It can provide the necessary data to determine sustainable conservation practices needed now and in the future, and help manage and protect our water resources.”
Researchers from Florida A&M University and California State Polytechnic University Pomona contributed to this work.
The research was supported by a $1.2 million grant from the National Institute of Food and Agriculture of the U.S. Department of Agriculture through Florida A&M University.make a difference: sponsored opportunity
Yashar Makhtoumi, Simeng Li, Victor Ibeanusi, Gang Chen. Evaluating Water Balance Variables under Land Use and Climate Projections in the Upper Choctawhatchee River Watershed, in Southeast US. Water, 2020; 12 (8): 2205 DOI: 10.3390/w12082205
A team of scientists at Utah State University has developed a new tool to forecast drought and water flow in the Colorado River several years in advance. Although the river’s headwaters are in landlocked Wyoming and Colorado, water levels are linked to sea surface temperatures in parts of the Pacific and Atlantic oceans and the water’s long-term ocean memory. The group’s paper, “Colorado River water supply is predictable on multi-year timescales owning to long-term ocean memory” was published October 9 by Communications Earth and Environment, an open-access journal from Nature Research.
The Colorado River is the most important water resource in the semi-arid western United States and faces growing demand from users in California, Arizona, New Mexico, Colorado and Utah. Because water shortages in the Colorado River impact energy production, food and drinking water security, forestry and tourism, tools to predict drought and low water levels could inform management decisions that affect millions of people.
Current drought forecasts focus on short-term indicators which limits their usefulness because short-term weather phenomena have too great an influence on the models.
“This new approach is robust and means that water managers, for the first time, have a tool to better estimate water supply in the Colorado River for the future,” Robert Gillies, professor in USU’s Department of Plants, Soils and Climate (PSC) and director of the Utah Climate Center, said. “The model can be run iteratively so every year a new forecast for the next three years can be created.”
In addition to ocean memory, water flows are impacted by land systems — including soils, groundwater, vegetation, and perennial snowpack — which play important roles in tempering the effects of short-term precipitation events. The researchers hypothesized that multi-year predictions could be achieved by using long-term ocean memory and associated atmospheric effects and the filtering effects of land systems.
The study’s lead author, Yoshimitsu Chikamoto, assistant professor of earth systems modeling in USU’s PSC department, said the components of the complex climate model include simulations of clouds and aerosols in the atmosphere, land surface characteristics, ocean currents and mixing and sea surface heat and water exchange.
“These predictions can provide a more long-term perspective,” Chikamoto said. “So if we know we have a water shortage prediction we need to work with policymakers on allocating those water resources.”
Simon Wang, USU professor of climate dynamics, said water managers and forecasters are familiar with El Niño and La Niña and the ocean’s connections to weather in the southwestern U.S. However, the upper basin of the Colorado River is not in the southwest and forecasts have not connected the dynamics of parts of the oceans with the Colorado River as the new forecasting tool does.
Matt Yost, PSC assistant professor and USU Extension agroclimate specialist, said having a two-year lead-time on preparing for drought could have a huge impact on farmers as they plan crop rotations and make other business decisions.
Co-author Larissa Yocom, assistant professor of fire ecology in USU’s Department of Wildland Resources, said a tool that can provide a long-term forecast of drought in areas impacted by the Colorado River could give managers a jump-start in preparing for wildland fire seasons.
Wang said Utah Climate Center researchers have developed models of drought cycles in the region and have recently studied the dynamics of river flows and shrinking water levels in the Great Salt Lake.
“In doing that work, we know that water managers don’t have tools to forecast Colorado River flows very long into the future and that is a constraint on what they can do,” Wang said. “We have built statistical models in the past, and Yoshi (Chikamoto) has expertise and in-depth knowledge of ocean dynamics so we talked about giving this idea a try because we found nothing in the literature to model these dynamics in the upper basin.”
“Using our tool we can develop an operational forecast of the Colorado River’s water supply,” Chikamoto added
Yoshimitsu Chikamoto, S.-Y. Simon Wang, Matt Yost, Larissa Yocom, Robert R. Gillies. Colorado River water supply is predictable on multi-year timescales owing to long-term ocean memory. Communications Earth & Environment, 2020; 1 (1) DOI: 10.1038/s43247-020-00027-0
FOR MORE INFORMATION: Utah State University. “The Colorado river’s water supply is predictable owing to long-term ocean memory: Scientists develop new tool to forecast drought and water flow in the Colorado river.” ScienceDaily. ScienceDaily, 9 October 2020. <www.sciencedaily.com/releases/2020/10/201009084936.htm>.
The Mullen Fire, which has spread through more than 147,000 acres of Colorado and Wyoming forest in the past two weeks, reached the southern edge of the main drinking water source for Cheyenne, the Wyoming capital. Protection of Rob Roy Reservoir is a major priority, city officials say.
The wildfire began September 17, feeding on soaring winds and burning through dead timber, bush, and beetle-killed pine in the Medicine Bow-Routt National Forests. Firefighters have worked to slow its progress, yet the fire doubled in size last week. Mandatory evacuation orders are in effect for some Colorado and Wyoming residents.
Rob Roy Reservoir, the first step in Cheyenne’s drinking water system, is at the edge of the burn zone. The city pipes water from the reservoir to Lake Owen, a secondary storage site. After Lake Owen, water makes its way through two more reservoirs before entering the city treatment facility.
Although the facility can treat water polluted by fires, authorities are concerned about erosion at the reservoir, which could damage pipelines and degrade water quality. If sediment or debris is washed into the reservoir, it could trigger problems with the treatment process.
Clint Bassett, the Board of Public Utilities treatment manager, said Cheyenne officials are working closely with the U.S. Forest Service to protect the watersheds, which are west of the city.
“We don’t know the impact of the Mullen Fire at this time, but the location suggests there may be some adverse effects to the city of Cheyenne’s water collection system and water quality,” Bassett said in a news release.
Rob Roy Reservoir isn’t the only water-supply asset under threat during the recent wildfires in the western United States. More than 5 million acres of land has burned this year just in California, Oregon, and Washington, destroying water infrastructure and damaging watersheds.
Burned land and vegetation leave scars that last for years. They prevent water from fully absorbing into the earth, weaken the watershed, and cause more intense flooding and mudslides. Even a light rainstorm can unleash sediment after a severe wildfire.
Vegetation takes time to grow back. Jason Kean, a research hydrologist at the U.S. Geological Survey’s Landslide Hazard Program, told E&E News that depending on the size and intensity of the fire, it can take two to five years, if not longer, for the watershed to heal.
Fires can also poison drinking water with benzene and other harmful volatile organic chemicals. These contaminants could be released when plastic pipes melt. They could also be sucked into pipes when a water system loses pressure. Some residents of San Lorenzo Valley Water District have been told to not drink the water because of benzene contamination.
A study released earlier this year examined two destructive fires in California: the 2017 Tubbs Fire and the 2018 Camp Fire. The study found that not only do melted plastics and debris contaminate water, but polluted water can then contaminate piping and water supplies by flowing through any undamaged infrastructure.
The federal limit for benzene in drinking water is 5 parts per billion. Some drinking water samples from the Camp Fire came back with more than 2,000 parts per billion. From the Tubbs Fire, more than 40,000.
As the climate trends warmer and drier, global food security increasingly hinges on crops’ ability to withstand drought. But are scientists and producers focusing on the right metric when measuring crop-relevant drought? Not exactly, according to new research from University of Illinois scientists, who urge the scientific community to redefine the term.
“Plants have to balance water supply and demand. Both are extremely critical, but people overlook the demand side of the equation, especially in the U.S. Corn Belt,” says Kaiyu Guan, principal investigator on two new studies, Blue Waters professor in the Department of Natural Resources and Environmental Sciences and the National Center for Supercomputing Applications at Illinois.
The demand Guan refers to is atmospheric dryness, often expressed as vapor pressure deficit (VPD). The drier the air, the more moisture is sucked out of pores, or stomata, in plant leaves. Plants have to open stomata to take in carbon dioxide as their food, but if they sense the atmosphere is too dry, they’ll close pores to avoid drying out. Keeping stomata closed too long leads to reductions in photosynthesis, plant growth, and grain yield.
The kicker? Plants shut down stomata due to atmospheric dryness even when there’s an adequate supply of moisture in the soil.
“If you only consider rainfall and soil moisture, which is how most people think about drought, that’s mostly describing the supply side. Of course if you have low soil moisture, plants will be stressed by how much water they get. But the supply is often pretty sufficient, especially here in the U.S. Corn Belt,” Guan says. “However, the demand side from the atmosphere can also severely stress plants. We need to pay more attention to that drought signal.”
Guan’s two recent studies used multiple technological approaches, including field measurements, various sources of satellite data, hydrological model simulations, and government crop yield statistics. The first study, published in Agricultural and Forest Meteorology, used data from seven sites across the Corn Belt to conclude VPD accounts for nearly 90% of the changes in crop stomatal conductance, a proxy for drought stress, and approximately 85% of changes in gross primary productivity, a measure of productivity.
“By comparison, soil moisture typically accounts for 6-13% of these measures for corn and soybean, and up to 35% when considering time lag effects,” says Hyungsuk Kimm, doctoral student in Guan’s group and the study’s lead author.
In the other study, published in the Journal of Hydrology, Guan’s team focused on grain yield. Yield depends on many factors related to water cycles, but the researchers found that VPD explains the biggest proportion of variability in crop yield and also provides the earliest warning for yield loss when comparing with other water cycle metrics and traditional drought indices.
“This led us to build a new drought index integrating VPD, soil moisture, and measures of evapotranspiration, which can account for more than 70% of yield variation. Our index outperforms all the existing drought indices,” says Wang Zhou, postdoctoral researcher in Guan’s group and the study’s lead author.
Guan adds, “In these two studies, we tried to understand the demand side of drought from two major angles, one using eddy covariance data which measures landscape water and carbon use very accurately — the gold standard — and the other leveraging satellite data and model-simulated hydrological variables correlated with regional yield,” Guan says. “In both, we demonstrate VPD is more important than soil moisture to explain the crop drought response in the U.S. Midwest.”
Adjusting the drought concept for crops will be critical for global food security under a changing climate.
“When we look at climate change scenarios, the amount of rainfall is not changing much for the Corn Belt, but we for sure know temperature and VPD will increase here. That means not much will change on the supply side, but demand stress will increase significantly. And that type of stress is so connected to end-of-season crop yield,” Guan says.
His group is working on follow-up studies evaluating the role of irrigation in increasing supply and decreasing demand, but for now, Guan says breeding for improved water-use-efficiency could be an important part of the solution.make a difference: sponsored opportunity
Wang Zhou, Kaiyu Guan, Bin Peng, Jiancheng Shi, Chongya Jiang, Brian Wardlow, Ming Pan, John S. Kimball, Trenton E. Franz, Pierre Gentine, Mingzhu He, Jingwen Zhang. Connections between the hydrological cycle and crop yield in the rainfed U.S. Corn Belt. Journal of Hydrology, 2020; 590: 125398 DOI: 10.1016/j.jhydrol.2020.125398
FOR MORE INFORMATION: University of Illinois College of Agricultural, Consumer and Environmental Sciences. “Redefining drought in the US corn belt.” ScienceDaily. ScienceDaily, 30 September 2020. <www.sciencedaily.com/releases/2020/09/200930085218.htm>.
The Army Corps of Engineers wants public input as it assesses ways to reduce flood risk along Houston waterways. FEMA begins accepting applications for $500 million in flood resilience grants. The Department of Health and Human Services wants to test sewage as a coronavirus early-warning system. Three agencies sign a new management plan for federal dams in the Columbia River basin. Regulators say there is enough evidence to list two freshwater mussel species as threatened. USDA begins accepting applications for a pilot program for septic systems that fail due to unsuitable soil. And lastly, the EPA considers revising up to eight national drinking water rules.
By the Numbers
$500 million: Grant funding available to help communities reduce the risk of catastrophic floods. Of that amount, some $20 million is set aside for tribes. The Building Resilient Infrastructure and Communities grants encourage projects that update building codes and those that incorporate nature-based flood prevention: things like wetlands, green spaces, and room for water to flow. (FEMA)
$5 million: Grant funding available for a new pilot program to evaluate and test small-scale wastewater treatment systems for poor communities with septic systems that fail due to unsuitable soil. Applications from regional research collaboratives are due November 4 and can be submitted via http://www.grants.gov. (USDA)
Tracking the Coronavirus in Sewage The Department of Health and Human Services is seeking a contractor that could help test sewage for traces of the new coronavirus, CNBC reports.
Evidence of genetic material from the SARS-CoV-2 virus in sewage can be used to identify potential outbreaks more quickly than clinical data. The CDC has already said it would organize a national surveillance network.
The department says that testing will begin with a network of wastewater plants that treat the sewage of about 10 percent of U.S. residents. The project could scale up to cover about 30 percent of the country’s population, largely in the biggest cities.
CNBC notes that the solicitation appears to be tailored toward the services of a particular company: BioBot, a startup that began testing sewage earlier this year and now has partnerships in 42 states.
Threatened Mussels The U.S. Fish and Wildlife Service says that there is enough evidence to list two freshwater mussel species as “threatened” under federal protection laws.
Critical habitat for the longsolid and round hickorynut mussels extends from Alabama to Pennsylvania. This includes about 1,000 miles of river habitat.
Comments on the proposed listing are being accepted through December 28. Submit them via http://www.regulations.gov using docket number FWS-R4-ES-2020-0010.
Studies and Reports
Houston Flooding Study The Army Corps of Engineers released an interim report as part of its assessment of ways to reduce flooding risk along Houston’s Buffalo Bayou.
Options include a new reservoir (estimated cost: $2.1 billion to $2.9 billion), dredging and widening Buffalo Bayou ($946 million to $1.2 billion), and relocating businesses and apartments downstream ($2.3 billion). There are a number of smaller options that could be included in those three options.
The Corps operates two dams on the bayou and its tributaries, which were inundated during Hurricane Harvey in 2017. Several factors account for the area’s increasing flood risk since the dams were built in the 1940s: population growth, more pavement, and higher-intensity rainfall.
The interim report does not make any conclusions or recommendations. Those will be part of the final report. Before then, the public has a chance to weigh in. Submit comments by November 2 to BBTRS@usace.army.mil.
Columbia River Dams Three federal agencies signed a record of decision on a new management plan for federal dams in the Columbia River basin.
Intended to improve the health of the basin’s salmon runs while accounting for the dams’ other authorized purposes — flood control, navigation, hydropower, water supply — the plan prioritizes spilling more water from the dams. Spilling water is a way to prevent outbound salmon from being killed in the turbines.
The plan does not take the step that some environmental groups and tribes had wanted: breaching four dams on the Lower Snake River.
On the Radar
EPA Drinking Water Rules Review Every six years, the EPA is required to review federal drinking water rules to determine, based on new data, whether any require revision.
The latest review found eight rules that could need updating. Those rules relate to microbial contaminants like Legionella and Giardia, as well as the chemical byproducts of water disinfection.
The agency will hold an online meeting on October 14 and 15 to hear expert testimony and public input about potential revisions.
The agenda is here. Register via the above link by October 12.
Environmental Finance Board Meeting Scheduling conflict alert: the Environmental Finance Advisory Board, which advises the EPA on the important question ‘How to pay for it?’, will hold a public meeting on October 14 and 15.
On the agenda: the EPA Office of Water will respond to a board report on stormwater financing and consolidating smaller water systems in regional blocs.
What Is a Showerhead The Department of Energy is giving the public an additional two weeks to comment on its proposal to revise the definition of “showerhead.”
The revision would allow for high-end, multi-nozzle fixtures to use more water than current efficiency standards.
Submit comments by October 14. Send them to Showerheads2020TP0002@ee.doe.gov with the subject line EERE-2014-BT-TP-0002.
Federal, state and local governments all have a hand in protecting public water systems and private wells from contamination.
This story was co-published with Ensia, a solutions-focused nonprofit media outlet reporting on our changing planet.
Editor’s note: This story is the first in a nine-month investigation of drinking water contamination across the U.S. The series is supported by funding from Park Foundation and Water Foundation.
By Brett Walton, Circle of Blue
Who’s responsible for making sure the water you drink is safe? Ultimately, you are. But if you live in the U.S., a variety of federal, state and local entities are involved as well.
The Safe Drinking Water Act (SDWA) forms the foundation of federal oversight of public water systems — those that provide water to multiple homes or customers. Congress passed the landmark law in 1974 during a decade marked by accumulating evidence of cancer and other health damage caused by industrial chemicals that found their way into drinking water. The act authorized the U.S. Environmental Protection Agency for the first time to set national standards for contaminants in drinking water. The EPA has since developed standards for 91 contaminants, a medley of undesirable intruders that range from arsenic and nitrate to lead, copper and volatile organic chemicals like benzene.
In 1996, amendments to the SDWA revised the process for developing drinking water standards, which limit the levels of specific contaminants. Nearly a quarter century after those amendments, an increasing number of policymakers and public health advocates today argue that the act is failing its mission to protect public health and is once again in need of major revision.
The process for setting federal drinking water contaminant limits, which is overseen by the EPA, was not designed to be speedy. First, the EPA identifies a list of several dozen unregulated chemical and microbial contaminants that might be harmful. Then water utilities, which are in charge of water quality monitoring, test their treated water to see what shows up. The identification and testing is done on a five-year cycle. The EPA examines those results and, for at least five contaminants, as required by the SDWA, it determines whether a regulation is needed. Three factors go into the decision: Is the contaminant harmful? Is it widespread at high levels? Will a regulation meaningfully reduce health risks? If the answer is “Yes” to all three, then a national standard will be forthcoming. Altogether, the process can take a decade or more from start to finish.
Usually, however, one of the three answers is “No.” Since the 1996 amendments were passed, the EPA has not regulated any new contaminants through this process, though it has strengthened existing rules for arsenic, microbes and the chemical byproducts of drinking water disinfection. The agency did decide in 2011 that it should regulate perchlorate — which is used in explosives and rocket fuel and damages the thyroid — but reversed that decision in June 2020, claiming that the chemical is not widespread enough to warrant a national regulation. Two other chemicals have recently advanced to the standard-writing stage. In February, EPA administrator Andrew Wheeler announced that the agency would regulate PFOA and PFOS, both members of the class of non-stick, flame-retarding chemicals known as PFAS. For those two chemicals, the EPA currently has issued a health advisory, which is a non-enforceable guideline.
The act of writing a national standard introduces more calculations: health risks, cost of treatment to remove the contaminant from water and availability of treatment technology. Considering these, the EPA establishes what is known as a maximum contaminant level goal (MCLG), which is the level at which no one is expected to become ill from the contaminant over a lifetime. The agency then sets a standard as close to the goal as possible, taking treatment cost into account. Standards, in the end, are not purely based on health protection and sometimes are higher than the MCLG. These standards, except for lead, apply to water as it leaves the treatment plant or moves throughout the distribution system. They do not apply to water from a home faucet, which could be compromised by old plumbing.
The EPA also has 15 “secondary” standards that relate to how water tastes and smells. Unless mandated by a state, utilities are not required to meet these standards.
Once the EPA sets a drinking water standard, the nation’s roughly 50,000 community water systems — plus tens of thousands of schools, office buildings, gas stations and campgrounds that operate their own water systems — are obligated to test for the contaminant. If a regulated substance is found, system operators must treat the water so that contaminant concentrations fall below the standard.
Omissions and Nuances
That is the regulatory process at the federal level. But there are omissions and nuances.
One big omission is private wells. Water in wells that supply individual homes is not regulated by federal statute. Rather, private well owners are responsible for testing and treating their own well water. The U.S. Geological Survey estimates that about 15% of U.S. residents use a private well. Some states, such as New Jersey, require that private wells be tested for contaminants before a home is sold. County health departments might also have similar point-of-sale requirements.
The nuance comes at the state level. States generally carry out the day-to-day grunt work of gathering water quality data from utilities and enforcing action against violations. To gain this authority, they must set drinking water standards that are at least as protective as the federal ones. If they want, they can set stricter limits or regulate contaminants that the EPA has not touched.
State authority had long been uncontroversial because only a few states — California and some northeastern states — were setting their own standards. That has changed in the last few years as states, responding to public pressure in the absence of an EPA standard, began regulating PFAS compounds.
“There was always a little bit of state standards-setting,” says Alan Roberson, executive director of the Association of State Drinking Water Administrators, an umbrella group for state regulators. “But it’s gone from a little bit to a lot.”
Six states — Massachusetts, Michigan, New Hampshire, New Jersey, New York and Vermont — adopted drinking water standards for certain PFAS compounds, while four others, including North Carolina and Minnesota, have issued health advisories or guidelines for groundwater cleanup.
States are also putting limits on other chemicals that the EPA has ignored. In July, New York adopted the nation’s first drinking water standard for 1,4-dioxane, a synthetic chemical that was used before the 1990s as an additive to industrial solvents. The EPA deems it likely to cause cancer, but the agency has not regulated it in drinking water. In 2017, California approved a limit for 1,2,3-TCP, another manufactured industrial solvent that the EPA considers likely to be carcinogenic.
The burst of state standards, especially for PFAS chemicals, has raised eyebrows. Some lawmakers worry that mismatched standards are confusing to residents. New York and New Jersey, for instance, set different limits on PFOA and PFOS in drinking water. “This can create poor risk communication and a crisis of confidence by the public who have diminished trust in their state’s standard when it fails to align with a neighboring state,” Rep. Paul Tonko said during a House Energy and Commerce subommittee hearing in July.
Tonko, from New York, argued that the federal process “has not worked,” pointing to the two-plus decades since a new contaminant was regulated.
Other representatives countered with the view that the EPA should concentrate on a select number of the most concerning contaminants so as not to overwhelm utilities and states with too many rules that are too hastily put together. Rep. John Shimkus from Illinois, echoing statements made by other committee members, said he does not want a system in which “quantity makes quality.”
This debate, and other considerations like regional drinking water standards, is likely to carry over into the next Congress.
Researchers at the University of California San Diego report in a new study a way to improve groundwater monitoring by using a remote sensing technology (known as InSAR), in conjunction with climate and land cover data, to bridge gaps in the understanding of sustainable groundwater in California’s San Joaquin Valley.
Their work could be revolutionary for managing groundwater use in agricultural regions around the world, as groundwater monitoring and management have been notoriously difficult to carry out due to lack of reliable data.
The satellite-based InSAR (interferometric synthetic aperture radar) is used to make high-resolution maps of land surface motion in space and time, including measurement of subsidence (or sinking). Subsidence can occur when large amounts of groundwater are removed from underground stores, called aquifers.
The study, published in the journal Environmental Research Letters, took advantage of the incredibly fine-scale resolution of InSAR to evaluate subsidence patterns according to crop type, revealing surprising results. For example, despite reports of high water consumption by fruit and nut crops in California, the crop types with the greatest rates of subsidence, and by association the greatest rates of groundwater use, were field crops such as corn and soy, followed by pasture crops like alfalfa, truck crops like tomatoes, and lastly, fruit and nut crops like almonds and grapes.
“Our initial hypothesis was that fruit and nut crops would be associated with some of the highest rates of subsidence, but we found the opposite,” said study lead author, Morgan Levy, an assistant professor with a joint appointment with UC San Diego’s Scripps Institution of Oceanography and School of Global Policy and Strategy.
Because displacement is a response to groundwater storage change in locations with varying geology, soils and vegetation, the interpretation of InSAR varies across locations, unlike satellite measurements of climate that have the same interpretation in any location. Therefore, InSAR must be combined with other sources of geophysical data to achieve location-specific insight into groundwater use.
By combining InSAR with other land surface datasets including land cover, potential evapotranspiration (a measure of plant water demand), and the location of surface water supply networks, UC San Diego researchers found that between 2015 and 2017, subsidence occurred at much higher rates in irrigated cultivated land compared to undeveloped land, and in dry surface water-limited years relative to wet years.
Over the study period, there was a median 272 millimeters (or 16 inches) of total cumulative subsidence for field crops (like corn and soy), and a dry water year subsidence rate of 131 millimeters (5 inches) per year. For fruit and nut crops, (like almonds and grapes) there was a median 62 millimeters (2.5 inches) of total subsidence over the study period, and a dry water year subsidence rate of 31 millimeters (1 inch) per year.
“The outcome might be explained by two things. First, on average fruits and nuts require less water physiologically, compared to field and pasture crops. Second, field and pasture crops tend to use irrigation methods that are less efficient and higher-volume than those used by fruit and nut crops,” Levy said. “However, fruits and nuts may still consume greater total volumes of water because they occupy more land area, even if their groundwater use intensity is less.”
Methods and findings from this research could be used to support the state’s ongoing effort to prevent overdraft of groundwater aquifers. Groundwater is a critical resource both nationally and globally: In the U.S., groundwater is a source of drinking water for roughly half of the population, and constitutes the largest source of irrigation water for agriculture. Irrigation accounts for approximately 70 percent of total U.S. groundwater withdrawals, and California has the highest rates of groundwater pumping in the nation.
“Our findings indicate that in the Central Valley, the costs and benefits of transitions away from field crops and towards fruit and nut crops in recent years are more complex than typically assumed,” Levy added. “Our results suggest the possibility that transitions to fruit and nut cultivation might be desirable, at least from a groundwater sustainability perspective, although more research is needed to confirm this.”
Global potential to advance groundwater monitoring and management
California is an example of a semi-arid and irrigation-dependent climate for agriculture. Coordinated efforts from the UC San Diego team of climate scientists and geophysicists to link subsidence, groundwater and surface water use, and crop production data across comparable time and space scales has tremendous potential to advance groundwater monitoring and management in agricultural regions in other parts of the world, said the authors.
In the San Joaquin Valley during wet years, farmers may receive up to 100 percent of their surface water allocations, while in extremely dry years, they may receive none. When surface water supplies are unavailable, farmers mine groundwater. Thus, groundwater has become increasingly important under climate change, as California and many parts of the world have experienced surface water shortages. However, excessive pumping does occur, even in relatively wet years. And, aquifers can run out.
In 2014, California passed legislation mandating a gradual, locally led shift towards sustainable use of groundwater — the resource on which 85 percent of its population and much of its $50-billon agriculture industry rely. The data from InSAR can be critical to the state’s efforts to perform effective monitoring and management in response to climate change.
While the legislation has encouraged local agencies to begin to use InSAR for documenting land subsidence, uses of InSAR for direct monitoring of groundwater use are early in their development. The UC San Diego research efforts provide an example of how water managers might use satellite data sources, including InSAR, to directly monitor local relationships between subsidence, groundwater pumping and crop portfolios.
“The promise of InSAR lies in our ability to combine it with other sources of geophysical and social data to answer water policy-relevant questions,” Levy and co-authors wrote. “We provide a preview of the power of such a synthesis, demonstrating that spatial patterns of subsidence and their relationship to agricultural cultivation and associated water demand are clear and robust.”
They concluded, “Our findings suggest that policy levers supporting sustainable groundwater management might benefit from consideration of the groundwater use intensity of crop selection, not only the difficult-to-define sustainability of groundwater extraction volumes over groundwater aquifer boundaries that remain uncertain and that are costly to delineate.”make a difference: sponsored opportunity
Morgan C Levy, Wesley R Neely, Adrian A Borsa, Jennifer A Burney. Fine-scale spatiotemporal variation in subsidence across California’s San Joaquin Valley explained by groundwater demand. Environmental Research Letters, 2020; DOI: 10.1088/1748-9326/abb55c
FOR MORE INFORMATION: University of California – San Diego. “Satellite imaging to map groundwater use in California’s central valley: Satellite data reveal variability in intensity of groundwater use for different crops, a boon for irrigation policymaking across the state.” ScienceDaily. ScienceDaily, 1 October 2020. www.sciencedaily.com/releases/2020/10/201001113646.htm
Healthy ecosystems underpin delivery of water supplies and water quality, and guard against water-related hazards and disasters. The conservation and sustainable use of biodiversity may therefore be regarded as foundational to the whole 2030 Agenda.
Earlier this month, the UN’s Global Biodiversity Outlook 5 report was published by the UN Convention on Biological Diversity (CBD). The report offers an authoritative overview of the state of nature and outlines eight major transitions needed to slow, then halt nature’s accelerating decline.
The land and forests transition: conserving intact ecosystems, restoring ecosystems, combatting and reversing degradation, and employing landscape level spatial planning to avoid, reduce and mitigate land-use change
The sustainable agriculture transition: redesigning agricultural systems through agroecological and other innovative approaches to enhance productivity while minimizing negative impacts on biodiversity
The sustainable food systems transition: enabling sustainable and healthy diets with a greater emphasis on a diversity of foods, mostly plant-based, and more moderate consumption of meat and fish, as well as dramatic cuts in the waste involved in food supply and consumption
The sustainable fisheries and oceans transition: protecting and restoring marine and coastal ecosystems, rebuilding fisheries and managing aquaculture and other uses of the oceans to ensure sustainability, and to enhance food security and livelihoods
The cities and infrastructure transition: deploying “green infrastructure” and making space for nature within built landscapes to improve the health and quality of life for citizens and to reduce the environmental footprint of cities and infrastructure
The sustainable freshwater transition: an integrated approach guaranteeing the water flows required by nature and people, improving water quality, protecting critical habitats, controlling invasive species and safeguarding connectivity to allow the recovery of freshwater systems from mountains to coasts
The sustainable climate action transition: employing nature-based solutions, alongside a rapid phase-out of fossil fuel use, to reduce the scale and impacts of climate change, while providing positive benefits for biodiversity and other sustainable development goals
The biodiversity-inclusive One Health transition: managing ecosystems, including agricultural and urban ecosystems, as well as the use of wildlife, through an integrated approach, to promote healthy ecosystems and healthy people.
Access the report Global Biodiversity Outlook 5 here.
Although less than one per cent of all water in the world is freshwater, it is what we drink and use for agriculture. In other words, it’s vital to human survival. York University researchers have just created a publicly available water quality database for close to 12,000 freshwater lakes globally — almost half of the world’s freshwater supply — that will help scientists monitor and manage the health of these lakes.
The study, led by Faculty of Science Postdoctoral Fellow Alessandro Filazzola and Master’s student Octavia Mahdiyan, collected data for lakes in 72 countries, from Antarctica to the United States and Canada. Hundreds of the lakes are in Ontario.
“The database can be used by scientists to answer questions about what lakes or regions may be faring worse than others, how water quality has changed over the years and which environmental stressors are most important in driving changes in water quality,” says Filazzola.
The team included a host of graduate and undergraduate students working in the laboratory of Associate Professor Sapna Sharma in addition to a collaboration with Assistant Professor Derek Gray of Wilfrid Laurier University, Associate Professor Catherine O’Reilly of Illinois State University and York University Associate Professor Roberto Quinlan.
The researchers reviewed 3,322 studies from as far back as the 1950s along with online data repositories to collect data on chlorophyll levels, a commonly used marker to determine lake and ecosystem health. Chlorophyll is a predictor of the amount of vegetation and algae in lakes, known as primary production, including invasive species such as milfoil.
“Human activity, climate warming, agricultural, urban runoff and phosphorus from land use can all increase the level of chlorophyll in lakes. The primary production is most represented by the amount of chlorophyll in the lake, which has a cascading impact on the phytoplankton that eat the algae and the fish that eat the phytoplankton and the fish that eat those fish,” says Filazzola. “If the chlorophyll is too low, it can have cascading negative effects on the entire ecosystem, while too much can cause an abundance of algae growth, which is not always good.”
Warming summer temperatures and increased solar radiation from decreased cloud cover in the northern hemisphere also contributes to an increase in chlorophyll, while more storm events caused by climate change contribute to degraded water quality, says Sharma. “Agricultural areas and urban watersheds are more associated with degraded water quality conditions because of the amount of nutrients input into these lakes.”
The researchers also gathered data on phosphorus and nitrogen levels — often a predictor of chlorophyll — as well as lake characteristics, land use variables, and climate data for each lake. Freshwater lakes are particularly vulnerable to changes in nutrient levels, climate, land use and pollution.
“In addition to drinking water, freshwater is important for transportation, agriculture, and recreation, and provides habitats for more than 100,000 species of invertebrates, insects, animals and plants,” says Sharma. “The database can be used to improve our understanding of how chlorophyll levels respond to global environmental change and it provides baseline comparisons for environmental managers responsible for maintaining water quality in lakes.”
The researchers started looking only at Ontario lakes, but quickly expanded it globally as although there are thousands of lakes in Ontario a lot of the data is not as readily available as it is in other regions of the world.
“The creation of this database is a feat typically only accomplished by very large teams with millions of dollars, not by a single lab with a few small grants, which is why I am especially proud of this research,” says Sharma.make a difference: sponsored opportunity
Alessandro Filazzola, Octavia Mahdiyan, Arnab Shuvo, Carolyn Ewins, Luke Moslenko, Tanzil Sadid, Kevin Blagrave, Mohammad Arshad Imrit, Derek K. Gray, Roberto Quinlan, Catherine M. O’Reilly, Sapna Sharma. A database of chlorophyll and water chemistry in freshwater lakes. Scientific Data, 2020; 7 (1) DOI: 10.1038/s41597-020-00648-2
FOR MORE INFO: York University. “New freshwater database tells water quality story for 12K lakes globally.” ScienceDaily. ScienceDaily, 22 September 2020. <www.sciencedaily.com/releases/2020/09/200922083910.htm>.