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Isotopic Analysis Reveals Origins of Organic Matter in Martian Sediments

Mars’ ancient geological features suggest the presence of water in the past, and recent studies of sediments from Gale Crater reveal organic matter with unique...

Studies on Mars’ Gale Crater sediments show unique organic compositions that suggest atmospheric influences, highlighting non-biological processes in organic matter formation. (Artist’s concept.) Credit: SciTechDaily.comMars’ ancient geological features suggest the presence of water in the past, and recent studies of sediments from Gale Crater reveal organic matter with unique isotopic compositions, pointing to atmospheric processes, not biological activity, as the source of this organic material.Mars’ Geological PastAlthough Mars presents a barren, dusty landscape with no signs of life so far, its geological features such as deltas, lakebeds, and river valleys strongly suggest a past where water once flowed abundantly on its surface. To explore this possibility, scientists examine sediments preserved near these formations. The composition of these sediments holds clues about the early environmental conditions, the processes that shaped the planet over time, and even potential signs of past life.Insights From Gale CraterIn one such analysis, sediments collected by the Curiosity rover from Gale Crater, believed to be an ancient lake formed approximately 3.8 billion years ago due to an asteroid impact, revealed organic matter. However, this organic matter had a significantly lower amount of the carbon-13 isotope (13C) relative to carbon-12 isotopes (12C) compared to what is found on Earth, suggesting different processes of organic matter formation on Mars. The atmospheric origin of organic matter suggests that Mar surfaces may contain larger amounts of organic compounds than previously anticipated. Credit: Tokyo TechNew Research FindingsNow, a study elucidates this discrepancy, finding that the photodissociation of carbon dioxide (CO2) in the atmosphere to carbon monoxide (CO) and subsequent reduction result in organic matter with depleted 13C content. The research, led by Professor Yuichiro Ueno from Tokyo Institute of Technology and Professor Matthew Johnson from the University of Copenhagen, was published in the journal Nature Geoscience on May 9, 2024.“On measuring the stable isotope ratio between 13C and 12C, the Martian organic matter has a 13C abundance of 0.92% to 0.99% of the carbon that makes it up. This is extremely low compared to Earth’s sedimentary organic matter, which is about 1.04%, and atmospheric CO2, around 1.07%, both of which are biological remnants, and are not similar to the organic matter in meteorites, which is about 1.05%,” explains Ueno.Isotopic Fractionation on MarsEarly Mars had an atmosphere rich in CO2 containing both 13C and 12C isotopes. The researchers simulated different conditions of the Martian atmosphere’s composition and temperature in laboratory experiments. They found that when 12CO2 is exposed to solar ultraviolet (UV) light, it preferentially absorbs UV radiation, leading to its dissociation into CO depleted in 13C, leaving behind CO2 enriched in 13C.This isotopic fractionation (separation of isotopes) is also observed in the upper atmospheres of Mars and Earth, where UV irradiation from the Sun causes CO2 to dissociate into CO with depleted 13C content. In a reducing Martian atmosphere, CO transforms into simple organic compounds such as formaldehyde and carboxylic acids. During the early Martian era, with surface temperatures close to the freezing point of water and not exceeding 300 K (27°C), these compounds may have dissolved in water and settled in sediments.Implications for Martian SedimentsUsing model calculations, the researchers found that in an atmosphere with a CO2 to CO ratio of 90:10, a 20% conversion of CO2 to CO would lead to sedimentary organic matter with δ13CVPDB values of -135‰. Also, the remaining CO2 would be enriched in 13C with δ13CVPDB values of +20‰. These values closely match those seen in sediments analyzed by the Curiosity rover and estimated from a Martian meteorite. This finding points to an atmospheric process rather than a biological one as the main source of organic matter formation on early Mars.“If the estimation in this research is correct, there may be an unexpected amount of organic material present in Martian sediments. This suggests that future explorations of Mars might uncover large quantities of organic matter,” says Ueno.Reference: “Synthesis of 13C-depleted organic matter from CO in a reducing early Martian atmosphere” by Yuichiro Ueno, Johan A. Schmidt, Matthew S. Johnson, Xiaofeng Zang, Alexis Gilbert, Hiroyuki Kurokawa, Tomohiro Usui and Shohei Aoki, 9 May 2024, Nature Geoscience.DOI: 10.1038/s41561-024-01443-z

Newsom administration unveils new $20-billion cost estimate for delta water tunnel

A new analysis shows that building a California water tunnel would cost $20 billion. State officials say the project's benefits would far outweigh the costs.

Gov. Gavin Newsom’s administration announced that the estimated cost of building a tunnel to transport water beneath the Sacramento-San Joaquin River Delta has risen to $20.1 billion.The estimate is part of a new cost-benefit analysis by the California Department of Water Resources, which concluded that the projected benefits of constructing the water tunnel would far outweigh the costs.State officials released the analysis Thursday, saying the proposed Delta Conveyance Project is vital to improving the reliability of water supplies in the face of climate change, sea level rise and the risks of an earthquake that could put existing infrastructure out of commission for months.The state estimates that the project’s benefits would total nearly $38 billion by offsetting steep reductions in water deliveries due to existing infrastructure limitations and climate change. A gull flies above McLeod Lake in Stockton. (Brian van der Brug/Los Angeles Times) “The project easily passes a benefit-cost test,” said David Sunding, a UC Berkeley emeritus professor who led the analysis as a consultant for the state. “The benefits clearly justify the costs.” Aggressive and impactful reporting on climate change, the environment, health and science. The last time the state produced an estimate, in 2020, the price tag came to $16 billion. The cost increase, Sunding said, is almost entirely due to inflation. The projected benefits also increased.The cost analysis is the state’s latest step toward building the 45-mile tunnel, which would create a second route to draw water from the Sacramento River into the aqueducts of the State Water Project.Newsom says the project is critical for California’s future, but opponents argue it is a costly boondoggle that would harm the delta and further imperil its ecosystem.Environmental groups, Indigenous tribes, fishing organizations and local agencies have filed lawsuits seeking to block the project.This week, dozens of groups filed protests with the State Water Resources Control Board challenging a state petition to change its “point of diversion” in the delta — one of the steps necessary to move forward with construction.The State Water Project supplies 27 million people and about 750,000 acres of farmland — fueling a $2.3-trillion portion of the state’s economy. (Brian van der Brug/Los Angeles Times) But state officials say the state’s existing pumping infrastructure in the south delta, which draws water into the California Aqueduct, is vulnerable to the more intense extremes driven by climate change, as well as sea level rise.They estimate that if the state relies on its current infrastructure, there would likely be a 22% reduction in water deliveries by 2070. However, construction of the tunnel would boost supplies by an estimated 400,000 acre-feet annually, compared to the “no project” alternative.The estimates included an analysis of impacts from sea level rise — using scenarios of a 1.8 feet or 3.5 feet rise by 2070 — which would bring increasing risks of delta levees failing or being overtopped, and higher salinity water encroaching on existing infrastructure.State officials also analyzed the risk that a major earthquake would pose to the existing infrastructure, which they say could disrupt deliveries of supplies for months. Sunding said the tunnel would have a “superior ability” to withstand earthquakes and would make the state’s system less vulnerable. (Brian van der Brug/Los Angeles Times) “I get a lump in my throat when I look at the potential for a catastrophic failure in the delta,” said Karla Nemeth, director of the state Department of Water Resources. “This is a project that just provides enormous value to the broad California economy.”Nemeth said the analysis shows that doing nothing would mean substantial costs for the state through frequent water shortages, mandatory restrictions in cities, and reductions in agricultural supplies that would force farmers to leave fields dry and fallow.“It is vastly more efficient and economical to avoid declining supplies,” Nemeth said.The costs of the project would be paid for by urban and agricultural water districts that decide to participate. The state’s cost-benefit analysis is intended to provide information that local water agencies, such as the Metropolitan Water District of Southern California, will consider. The Antioch Bridge over the San Joaquin River. (Brian van der Brug/Los Angeles Times) In preparing the updated cost estimate, the Delta Conveyance Design and Construction Authority examined potential “design and construction innovations” that could reduce the overall costs by about $1.2 billion.Currently, about 56% of water deliveries from the State Water Project supply urban areas, while nearly 44% go to agriculture.The analysis projects that with the tunnel, California would have fewer periods of mandatory water rationing and also less severe rationing, Sunding said. The project “helps to preserve the supplies that would otherwise be eroded through climate change,” he said.State officials also compared the costs of additional supplies from the tunnel, at $1,325 per acre-foot, to the costs of additional supplies through investments in desalination, wastewater recycling, stormwater capture and conservation.Sunding said they found the median costs of these other types of investments would be higher, with the exception of conservation, which is “in the same ballpark” with the project.“But it is important to note that we’ve done a lot of water conservation in the state, particularly in Southern California and some parts of the Bay Area, and a lot of the cheapest water conservation projects have already been done,” Sunding said. “So there are limits to how much more water conservation there can be.”However, other experts say California still has a great deal of potential to continue reducing water use through conservation. Researchers with the Pacific Institute, a water think tank, found in a 2022 study that the state could reduce water use by more than 30% in cities and suburbs by investing in measures to use water more efficiently.Opponents of the tunnel project have argued the state should instead invest in other approaches in the delta, such as shoring up levees and restoring natural floodplains to reduce flood risks, while changing water management to protect the estuary’s health. An angler casts into Bethany Reservoir in Byron. (Brian van der Brug/Los Angeles Times) Fish populations have suffered declines in recent years, and environmentalists say the tunnel would cause additional ecological harm.State officials say the tunnel would lessen limitations on water deliveries linked to fish protections at the state’s existing pumping facilities in the south delta.They point to this year as an example. Despite a wet winter and ample river flows, a rise in the deaths of steelhead trout and other fish in areas around the pumps forced reductions in pumping.The Department of Water Resources said that if the delta tunnel had been in operation this year, an additional 909,000 acre-feet of water could have been delivered from intakes in the north delta, helping to resolve what officials described as “difficult conflicts” in the south delta.“The status quo is not an option going forward. It’s just not something that can be maintained,” Sunding said. “One way or another, the system is going to change. Climate change is going to have its impact.” Newsletter Toward a more sustainable California Get Boiling Point, our newsletter exploring climate change, energy and the environment, and become part of the conversation — and the solution. You may occasionally receive promotional content from the Los Angeles Times.

$20 billion: The Delta tunnel’s new price tag

The centerpiece of California's water wars pits Gov. Newsom against local communities and environmentalists. A new report says the benefits of the tunnel exceed the cost since other water supplies would cost more.

In summary The centerpiece of California’s water wars pits Gov. Newsom against local communities and environmentalists. A new report says the benefits of the tunnel exceed the cost since other water supplies would cost more. California’s contentious and long-debated plan to replumb the Sacramento-San Joaquin Delta and pump more water south finally has a price tag: about $20 billion.  The new estimate for the Delta tunnel project — which would transform the massive water system that sends Northern California water south to farms and cities — is $4 billion higher than a 2020 estimate, largely because of inflation. Included is almost $1.2 billion to offset local harms and environmental damage, such as impacts on salmon and rare fish that state officials have called “potentially significant.” The goal of the project is to collect and deliver more water to two-thirds of California’s population and 750,000 acres of farmland during wet periods, shore up supplies against the threats of climate change and protect the system from earthquakes. But environmental groups, many Delta residents, tribes and the fishing industry have long warned that the tunnel could put the imperiled Delta ecosystem at even greater risk, sapping freshwater flows needed for fish, farms and communities in the region.  The tunnel has been the focus of intense debate in California for more than 60 years. It’s the epicenter of water wars that have pitted Delta locals, environmental groups, tribes and the fishing industry against state officials and water agencies that supply cities and farms, mostly in Southern California. The new report from the state Department of Water Resources comes as state water regulators weigh competing rescue plans for a region they have described as “in crisis” and in the midst of an “ecosystem collapse.”  Gov. Gavin Newsom backs the proposed project, calling it his “number one climate resilience program” and saying he hopes to get it permitted before he leaves office. The 45-mile tunnel would transport water from the Sacramento River around the Delta to a reservoir near Livermore, the first stop on the 444-mile California Aqueduct. The new estimate and report will help water suppliers in Southern California, the Central Coast and the Bay Area weigh whether it’s cost effective for them to buy the tunnel’s water. The state would issue revenue bonds to fund the project, then suppliers would have to pay back the costs.  Water agencies, such as the giant Metropolitan Water District of Southern California, are expected to have all of information they need to decide by the end of 2026, said Karla Nemeth, director of the Department of Water Resources, which operates the state’s massive water system. Building the tunnel could take until at least 2044, with construction and startup expected to start around 2029 and last roughly 15 years.  Had the tunnel been in place this year, it could have funneled 909,000 additional acre-feet of water south from intakes in the north Delta, according to state water officials. That’s nearly enough water to fill Folsom Lake, and could supply more than 9.5 million people for a year.  The total benefits of the project — calculated at around $38 billion — far outweigh the costs, according to the report, with every dollar spent expected to reap $2.20 in benefits. “In other words, doing nothing is more expensive,” said David Sunding, a UC Berkeley emeritus professor of environmental economics who led the cost-benefit analysis. Sunding said water deliveries from the tunnel would cost about $1,350 per acre-foot — less than the average cost for water generated by desalination, recycling and stormwater capture.  Another benefit to a tunnel, Sunding said, is earthquake preparedness for the state’s water delivery system, which is crossed by the major Hayward and San Andreas faults. A catastrophic earthquake that crumbles levees could interrupt water deliveries for nearly seven months, and degrade water quality for almost another year. Sunding said the tunnel would, ideally, allow water deliveries to continue in some form after quakes, or at least protect water quality. The tunnel could also increase water exports from the Sacramento River when pumping from the south Delta is limited to protect threatened and endangered species, Nemeth said. Thousands of threatened steelhead trout and endangered winter-run Chinook salmon have died this year from the pumping, according to state and federal estimates. But conservationists warn that a tunnel wouldn’t reduce the risk to fish: The existing pumps would still be operational — posing a continued threat to protected species. Environmental groups and fishing organizations have sued over the project, saying adding the tunnel would further reduce freshwater flows — increasing salt levels and harmful algal blooms, and harming native fish.  Tribes and environmental justice organizations also oppose the state’s application for a change in water rights to build and operate the tunnel. “The injurious impacts of mismanagement in the Bay-Delta can no longer be endured by Tribes and Delta communities,” Malissa Tayaba, vice chair of the Shingle Springs Band of Miwok Indians, said in a statement.  Jon Rosenfield, science director of San Francisco Baykeeper, called it “just the latest version of a plain old water grab.”  The state’s own environmental analysis warned two years ago that the tunnel could harm endangered and threatened fish, including the Delta smelt, winter-run chinook salmon and steelhead trout. Changes to flows at the intakes or downstream, for instance, could reduce migration, damage habitat and expose salmon and other native fish to more predators.  The analysis calls for thousands of acres of wetland restoration to offset the “potentially significant impacts” — projects that critics say have historically been slow and inefficient in California.  The Delta watershed supports about 80% of the state’s commercial salmon fishery, which was cancelled this year for the second time in a row because of plummeting populations.  “What better way to address declining salmon populations than by draining their homes?” Scott Artis, executive director of the Golden State Salmon Association, said in a recent statement. “Bravo, Governor, for turning healthy rivers and estuaries into a punchline that harms tens of thousands of families, businesses and employees across California and Oregon.”

Going With the Flow: Hogtown Creek Floodplain & Green Acre Park

Green Acre Park is an important stop along the creek’s journey and another example of how a community exists side by side with the natural resources that sustain it. For the residents that live near the park, and for the city of Gainesville as a whole, the protection and preservation of Hogtown Creek is vital to ensuring that future generations will have clean drinking water for years to come.

Going with the Flow: Exploring Loblolly Woods Nature Park

...more pollutants seep into the water as it travels further into the city, and Loblolly Park is a perfect example. Oil from cars, discarded trash, and animal waste from the roads, businesses, and apartments surrounding the park are swept up in the surface runoff. The runoff flows into the creek and contaminates the water.