Positive reinforcements help algorithm forecast underground natural reserves

artist's rendering of a person's handing next to a computer screen showing an algorithm

Texas A&M University researchers have designed a reinforcement-based algorithm that automates the process of predicting the properties of the underground environment, facilitating the accurate forecasting of oil and gas reserves.

Within the Earth’s crust, layers of rock hold bountiful reservoirs of groundwater, oil and natural gas. Now, using machine learning, researchers at Texas A&M University have developed an algorithm that automates the process of determining key features of the Earth’s subterranean environment. They said this research might help with accurate forecasting of our natural reserves.

Specifically, the researchers’ algorithm is designed on the principle of reinforcement or reward learning. Here, the computer algorithm converges on the correct description of the underground environment based on rewards it accrues for making correct predictions of the pressure and flow expected from boreholes.

“Subsurface systems that are typically a mile below our feet are completely opaque. At that depth we cannot see anything and have to use instruments to measure quantities, like pressure and rates of flow,” said Siddharth Misra, associate professor in the Harold Vance Department of Petroleum Engineering and the Department of Geology and Geophysics. “Although my current study is a first step, my goal is to have a completely automated way of using that information to accurately characterize the properties of the subsurface.”

The algorithm is described in the December issue of the journal Applied Energy.

Simulating the geology of the underground environment can greatly facilitate forecasting of oil and gas reserves, predicting groundwater systems and anticipating seismic hazards. Depending on the intended application, boreholes serve as exit sites for oil, gas and water or entry sites for excess atmospheric carbon dioxide that need to be trapped underground.

Along the length of the boreholes, drilling operators can ascertain the pressures and flow rates of liquids or gas by placing sensors. Conventionally, these sensor measurements are plugged into elaborate mathematical formulations, or reservoir models, that predict the properties of the subsurface such as the porosity and permeability of rocks.

But reservoir models are mathematically cumbersome, require extensive human intervention, and at times, even give a flawed picture of the underground geology. Misra said there has been an ongoing effort to construct algorithms that are free from human involvement yet accurate.

For their study, Misra and his team chose a type of machine-learning algorithm based on the concept of reinforcement learning. Simply put, the software learns to make a series of decisions based on feedback from its computational environment.

“Imagine a bird in a cage. The bird will interact with the boundaries of the cage where it can sit or swing or where there is food and water. It keeps getting feedback from its environment, which helps it decide which places in the cage it would rather be at a given time,” Misra said. “Algorithms based on reinforcement learning are based on a similar idea. They too interact with an environment, but it’s a computational environment, to reach a decision or a solution to a given problem.”

So, these algorithms are rewarded for favorable predictions and are penalized for unfavorable ones. Over time, reinforcement-based algorithms arrive at the correct solution by maximizing their accrued reward.

Another technical advantage of reinforcement-based algorithms is that they do not make any presuppositions about the pattern of data. For example, Misra’s algorithm does not assume that the pressure measured at a certain time and depth is related to what the pressure was at the same depth in the past. This property makes his algorithm less biased, thereby reducing the chances of error at predicting the subterranean environment.

When initiated, Misra’s algorithm begins by randomly guessing a value for porosity and permeability of the rocks constituting the subsurface. Based on these values, the algorithm calculates a flow rate and pressure that it expects from a borehole. If these values do not match the actual values obtained from field measurements, also known as historical data, the algorithm is penalized. Consequently, it is forced to correct its next guess for the porosity and permeability. However, if its guesses were somewhat correct, the algorithm is rewarded and makes further guesses along that direction.

The researchers found that within 10 iterations of reinforcement learning the algorithm was able to correctly and very quickly predict the properties of simple subsurface scenarios.

Misra noted that although the subsurface simulated in their study was simplistic, their work is still a proof of concept that reinforcement algorithms can be used successfully in automated reservoir-property predictions, also referred as automated history matching.

“A subsurface system can have 10 or 20 boreholes spread over a two- to five-mile radius. If we understand the subsurface clearly, we can plan and predict a lot of things in advance, for example, we would be able to anticipate subsurface environments if we go a bit deeper or the flow rate of gas at that depth,” Misra said. “In this study, we have turned history matching into a sequential decision-making problem, which has the potential to reduce engineers’ efforts, mitigate human bias and remove the need of large sets of labeled training data.”

He said future work will focus on simulating more complex reservoirs and improving the computational efficiency of the algorithm.

Hao Li of the University of Oklahoma was a contributor to this work. This research is funded by the United States Department of Energy.

FOR MORE INFORMATION: Texas A&M University

For Selenium in Rivers, Timing Matters

The Lower Gunnison River in Colorado, where scientists are testing for the substance selenium.
The sampling team on the main stem of the Lower Gunnison River, Colorado at Dominguez-Escalante Canyon. (Photo courtesy of the USGS).

elenium contamination of freshwater ecosystems is an ongoing environmental health problem around the world. A naturally occurring trace element, selenium levels are high in some geologic formations like sedimentary shales that form much of the bedrock in the Western United States. Soils derived from this bedrock, and weathering of shale outcrops, can contribute high levels of selenium to surrounding watersheds.

New research out this week in Environmental Science & Technology from UConn Assistant Professor of Natural Resources and the Environment Jessica Brandt with Travis Schmidt and colleagues at the United States Geological Survey (USGS) investigates some of the complexities of selenium and how it moves through the ecosystem  during runoff events and as a result of seasonal irrigation of selenium-enriched soils.

The research focused on the Lower Gunnison River Basin in Colorado, an area impacted by selenium-enriched bedrock known as the Upper Cretacous Mancos Shale, and designated critical habitat for the endangered razorback sucker (Xyrauchen texanus) and Colorado pikeminnow (Ptychocheilus lucius). Between June 2015 and October 2016, the research team sampled water and wildlife across six sampling trips and along 60 river miles between Austin and Grand Junction, CO.

Researchers processing water samples on the banks of the Gunnison River in Colorado, looking for traces of selenium.
The field crew processing samples along the Gunnison River, Colorado. (Phot courtesy of Travis Schmidt, USGS).

Brandt explains that the focus of the study was on the timing of selenium movement through the riverine food web. Particulate matter including algae take up selenium from the water at the base of the food web. Invertebrates and some small fish feed directly on the particulate material, and bigger fish then eat the invertebrates and smaller fish.

“Selenium is an essential micronutrient acquired through the diet, but excess exposure threatens the health of egg-laying animals, including fish and aquatic birds. On top of that, the timing of exposure matters. For instance, too much selenium as an embryo is particularly concerning because it impairs development and reduces the chances of hatching and survival to adult life stages. We wanted to know when, over the course of the year, are fish exposed to the highest concentrations of selenium in the food web? Do those periods coincide with windows of reproduction and early-life development? Are they aligned with periods of increased selenium mobilization to the river?”

For the most part, the answers to those questions were yes. Selenium concentrations reached their highest concentrations in fish prey in April and August 2016 when selenium is pulsed into the river from snowmelt and during irrigation of agricultural fields. By modeling fish concentrations from selenium levels lower in the food web, Brandt and collaborators predicted that whole-body selenium levels were highest during the spring and summer. During these periods, eggs are maturing in adult fish prior to spawning and young of the year fish are experiencing stages of development that are susceptible to high selenium exposures. (See sidebar)

Brandt explains the study is important because of its focus on a fast-flowing water system. Most case studies of waterbodies contaminated with selenium are about lakes and reservoirs where selenium reaches high concentrations in fish and birds after moving through the sediment-detrital pathway. Because the water moves more slowly in these systems, selenium has more opportunity to accumulate at the base of the food web. In rivers, on the other hand, it is thought that most of the selenium mobilized during periods of high flow will be flushed downstream before it can accumulate locally,

“We observed that green algae can take up selenium pretty rapidly during periods of high mobilization, likely from the water column directly. One hypothesis going forward is that algal uptake pathways for selenium entry to aquatic food webs, rather than sediment-detrital pathways, might dominate in rivers and streams. This study indicates that we need to be spending more time thinking about selenium risks in rivers.”

Brandt says this research has implications for the management of selenium sampling in rivers. For example, fish sampling typically happens in the fall when the results of this study suggest that selenium concentrations in fish might be at their lowest. Even still, the measured concentrations were high,

“We sampled speckled dace and roundtail chub in October 2015 and 2016,” says Brandt, “Whole-body selenium concentrations in more than 90% of these fish were well above four parts per million, which is a threshold supported by research showing adverse health effects like reduced growth and survival. Because the river is habitat for native endangered species, maintaining fish health is a priority.”

Selenium levels in the Lower Gunnison River Basin have been a concern for several decades now and Brandt explains that ongoing remediation efforts in the Gunnison have reduced levels by 43% since 1986. But perhaps more can be done to further bolster these efforts

“Do we need to be approaching selenium assessments in impaired rivers in a different way? Well, we see from this work that selenium concentrations in the food web are high even with drops in water concentrations over the last thirty plus years. This highlights that the food web is the primary driver of selenium exposure and potential toxicity risk.  More frequent monitoring of food web selenium in this system will give us the best information about how to manage selenium in order to meet fish conservation goals.”

FOR MORE INFORMATION: University of Connecticut

‘No Other Option’: Deadly India Floods Bare Conflicts From Hydropower Boom

Reuters
Kundan Singh, 48, poses for a picture near his home after a flash flood swept down a mountain valley destroying dams and bridges, in Raini village in the northern state of Uttarakhand, India, February 11, 2021. Picture taken February 11, 2021. REUTERS/Anushree Fadnavis

RAINI, India (Reuters) – Growing up in a remote tribal village high in the Indian Himalayas, Kundan Singh loved to play on a field by the sparkling Rishiganga river.

The 48-year-old recalls afternoons there competing in sports tournaments, surrounded by forests of pine.

Fifteen years ago, bulldozers descended on Raini village to build a dam, part of a push by India to increase hydroelectric power. The field was lost, and villagers have been in conflict with the Rishiganga Hydropower Project ever since.

The dam was swept away two weeks ago in a flash flood that also smashed bridges and another hydroelectric power station in the Dhauliganga river valley of Uttarakhand state, leaving over 200 feared dead.

Whatever the role of climate change, which is rapidly heating the world’s highest mountains, experts say rampant construction is adding to the burden weighing on rural communities across the Himalayas.

This building boom is creating conflict across the region, as shown by interviews with nearly two dozen Raini villagers, legal and technical documents, satellite imagery and photographs, and correspondence with local officials, some of it not previously reported.

“We wrote letters, we protested, we went to court, we did everything,” Singh said. “But no one heard us.”

JOBS DIDN’T COME

The 150 villagers are members of the Bhutia tribe of historically nomadic shepherds from Tibet, some of whom settled in India after a 1962 war with China closed the border.

Granted protected status with government quotas for jobs and education, many nonetheless live in poverty in the mountainous state, labouring on roads and construction sites, weaving woollen rugs and growing potatoes and pulses on small plots around a bend in the river.

Villagers were initially enthusiastic at the prospect of a power plant that promised jobs, according to court documents, the project’s impact assessment and minutes of a 2006 meeting between village leaders and representatives of the dam.

But the jobs did not come, Singh and other locals said. Those who managed to find work on the dam clashed with the owners over unpaid wages and alleged construction violations, according to court documents.

A paint company from Punjab controlled the dam during initial construction. It has not filed accounts since 2015, and its current directors could not be reached for comment. The project entered bankruptcy before being bought by the Kundan Group in 2018, and finally started operations last year. Executives at the conglomerate did not respond to calls and emails seeking comment.

As India seeks to nearly double its hydropower capacity by 2030, construction of dams in the region is increasingly leading to disagreements between plant owners and locals, said Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers and People, which has studied the conflicts.

“It happens with many projects,” he said. “People want to resist and oppose, but project developers… will always make promises of employment and development.”

In the Alaknanda basin, a cluster of streams that feeds the Ganges river – worshipped as a god by many Hindus – six hydroelectric dams have been constructed, according to Thakkar’s nonprofit. Eight more, including the Tapovan dam that was severely damaged in the Feb. 7 floods, are under construction, while a further 24 have been proposed.

A spokeswoman for India’s power ministry said the country has strict measures in place regarding the planning of hydropower projects and the rights of local people are always considered.

MUDDY BANKNOTES, RUBBLE

During the dam’s construction, blasts from explosives were frequent, according to interviews with about 20 residents and court documents.

The use of explosives in construction in the region was criticised after devastating floods in Uttarakhand in 2013, dubbed a “Himalayan tsunami” that claimed some 6,000 lives.

In 2019, Singh and his brother took a two-day bus journey to meet with lawyer Abhijay Negi, who recalled them arriving with a bundle of muddy banknotes collected from other residents as payment.

“Please help us save our village,” Singh told him.

Negi helped the men file a case against the Kundan Group unit operating the dam, alleging construction had left behind loose rubble and rocks, according to photographs and diagrams submitted as evidence.

Uttarakhand’s top court ruled there was evidence of “substantial damage” to the area that suggested explosives were being used for illegal mining, though it did not rule on when the damage occurred. The court ordered a local investigation, but it is not clear if this has happened and officials involved could not be reached.

High up on the mountain, almost all the Raini residents survived the floods. But Singh said the disaster has left many dreaming of escape.

“Many want to leave, but I will stay because I have no other option,” he said. “I will stay because of poverty.”

FOR MORE INFORMATION: https://www.usnews.com/news/world/articles/2021-02-22/no-other-option-deadly-india-floods-bare-conflicts-from-hydropower-boom

Over 7.9 Million Texans Still Facing Disrupted Water Supplies

Reuters
 Volunteer Elizabeth Murray helps hand water to local residents at Butler Stadium after the city of Houston implemented a boil water advisory following an unprecedented winter storm in Houston, Texas, U.S., February 21, 2021.

(Reuters) – Over 7.9 million people in Texas still had issues with their water supply as of Monday evening, authorities told Reuters, after a record-breaking freeze knocked out power stations last week.

Millions of Texans were advised to boil water before using it, though all power plants were back online over the weekend and power had been restored to most homes as the weather returned to normal.

Officials in Houston, the biggest city in the state, said water there was safe to use without boiling as of Sunday.

“As of 6 PM Central Time Monday, more than 1,200 public water systems have reported disruptions in service due to the weather, many of them leading to Boil Water Notices. This is affecting more than 7.9 million people, in 202 Texas counties”, a Texas Commission on Environmental Quality (TCEQ) spokesman said in an emailed statement.

“A total of 147 PWSs (public water systems) serving a population of more than 33,000 people are non-operational. In addition, 4 PWSs wastewater treatment facilities have reported as non-operational”, the spokesman added.

Texas Governor Greg Abbott said late on Sunday that he had joined the Texas Air Guard, the Texas National Guard and the U.S. military to distribute water.

“About 3.5 million bottles of water have been delivered”, the governor said in a tweet.

A deadly winter storm caused widespread blackouts last week across Texas, a state unaccustomed to extreme cold, killing at least two dozen people and knocking out power to more than 4 million people at its peak.

Texas is also bringing in plumbers from out of state to help repair burst pipes, the governor said on Sunday. Homeowners or renters who do not have insurance may be able to seek reimbursement from the Federal Emergency Management Agency (FEMA), he said.

U.S. President Joe Biden approved a major disaster declaration for Texas on Saturday that makes federal funding available to people harmed by the storm, including assistance for temporary housing and home repairs and low-cost loans.

U.S. Representative Alexandria Ocasio-Cortez said late on Sunday that she had amassed $5 million in her fundraising efforts to help Texans hard hit by last week’s winter storm.

FOR MORE INFORMATION: https://www.usnews.com/news/us/articles/2021-02-22/about-a-third-of-texans-still-facing-disrupted-water-supplies-cnn

Global study of 48 cities finds nature sanitizes 41.7 million tons of human waste a year

Global study of 48 cities finds nature sanitizes 41.7 million tons of human  waste a year

The first global-scale assessment of the role ecosystems play in providing sanitation finds that nature provides at least 18% of sanitation services in 48 cities worldwide, according to researchers in the United Kingdom and India. The study, published February 19 in the journal One Earth, estimates that more than 2 million cubic meters of the cities’ human waste is processed each year without engineered infrastructure. This includes pit latrine waste that gradually filters through the soil — a natural process that cleans it before it reaches groundwater.

“Nature can, and does, take the role of sanitation infrastructure,” said Alison Parker, a Senior Lecturer in International Water and Sanitation at Cranfield University in the United Kingdom and one of the authors of the study. “While we are not marginalizing the vital role of engineered infrastructure, we believe a better understanding of how engineered and natural infrastructure interact may allow adaptive design and management, reducing costs, and improving effectiveness and sustainability, and safeguard the continued existence of these areas of land.”

Wastewater treatment infrastructure that converts human feces into harmless products is an important tool for global human health. However, more than 25% of the world’s population did not have access to basic sanitation facilities in 2017 and another 14% used toilets in which waste was disposed of onsite. While some of this waste may be hazardous to local populations, previous research has suggested that natural wetlands and mangroves, for example, provide effective treatment services. The Navikubo wetland in Uganda processes untreated wastewater from more than 100,000 households, protecting the Murchison Bay and Lake Victoria from harmful contaminants, while in the United States coastal wetlands in the Gulf of Mexico remove nitrogen from the Mississippi River.

“We realized that nature must be providing sanitation services, because so many people in the world do not have access to engineered infrastructure like sewers,” adds Simon Willcock, a Senior Lecturer in Environmental Geography in Bangor University, UK, and another author of the study. “But the role for nature was largely unrecognized.”

To better understand how natural ecosystems process waste, the team from Bangor University, Cranfield University, Durham University, University of Gloucestershire, University of Hyderabad (India) and the Fresh Water Action Network, South Asia quantified sanitation ecosystem services in 48 cities containing about 82 million people using Excreta Flow Diagrams, which leverage a combination of in-person interviews, informal and formal observations, and direct field measurements to document how human fecal matter flows through a city or town. The researchers assessed all diagrams that were available on December 17th, 2018, focusing on those coded as “fecal sludge contained not emptied” (FSCNE), in which the waste is contained in a pit latrine or septic tank below ground but does not pose a risk to groundwater, for example, because the water table is too deep.

Conservatively, Willcock and colleagues estimate that nature processes 2.2 million cubic meters of human waste per year within these 48 cities. Since more than 892 million people worldwide use similar onsite disposal toilet facilities, they further estimate that nature sanitizes about 41.7 million tons of human waste per year before the liquid enters the groundwater — a service worth about $4.4 billion per year. However, the authors note that these estimates likely undervalue the true worth of sanitation ecosystem services, since natural processes may contribute to other forms of wastewater processing, though these are harder to quantify.

Willcock and colleagues hope that their findings will shed light on an important but often unrecognized contribution that nature makes to many people’s everyday lives, inspiring the protection of ecosystems such as wetlands that protect downstream communities from wastewater pollutants.

“We would like to promote a better collaboration between ecologists, sanitation practitioners and city planners to help nature and infrastructure work better in harmony, and to protect nature where it is providing sanitation services,” said Parker.

This work was prepared as part of the ESRC and ICSSR funded Rurality as a vehicle for Urban Sanitation Transformation (RUST) project.

Journal Reference:

  1. Willcock et al. Nature provides valuable sanitation servicesOne Earth, 2021 DOI: 10.1016/j.oneear.2021.01.003

FOR MORE INFORMATION: Cell Press. “Global study of 48 cities finds nature sanitizes 41.7 million tons of human waste a year.” ScienceDaily. ScienceDaily, 19 February 2021. <www.sciencedaily.com/releases/2021/02/210219111503.htm>.

Nestle to Sell North American Water Brands for $4.3 Billion, Focus on Premium Lines

Reuters

(REUTERS) – NESTLE SAID on Wednesday it would sell Pure Life and some other struggling North American water brands to two private equity firms for $4.3 billion, as the food giant doubles down on its premium offerings including Perrier.

The sale, to One Rock Capital Partners and Metropoulos & Co, includes brands such as Poland Spring, Deer Park, Ozarka, Ice Mountain, Zephyrhills, Arrowhead and Splash, as well as U.S. office beverage delivery service ReadyRefresh.

Perrier, S.Pellegrino and Acqua Panna, which contributed to the growth recovery of Nestle’s North American water business in the third quarter, are not part of the sale agreement, the company said.

“This sale enables us to create a more focused business around our international premium brands, local natural mineral waters and high-quality healthy hydration products,” Chief Executive Officer Mark Schneider said in a statement.

Nestle, headquartered in Vevey, Switzerland, said in June last year it was exploring a potential sale of part of its North American water business. Reuters exclusively reported its talks with One Rock Capital earlier this month.

New York-based One Rock said Dean Metropoulos, founder of Metropoulos & Co, would become Nestle Waters North America’s chairman and interim chief executive officer after the deal closes.

“As a private company, the business is expected to have greater resources and flexibility to drive continued growth, strengthen its existing operations,” One Rock partner Kimberly Reed said.

The Nestle Waters North America division has about 7,000 employees in the United States and more than 230 in Canada, according to One Rock.

One Rock manages about $3.2 billion of committed capital across three flagship funds, its website said.

FOR MORE INFORMATION: https://money.usnews.com/investing/news/articles/2021-02-16/nestle-to-sell-namerican-water-brands-to-buyout-firm-one-rock-for-43-billion

Tap water access linked to dengue risk

Image result for Tap water access linked to dengue risk

Dengue virus is among growing number of mosquito-borne viruses that have adapted to spread in urban environments and are spreading with the increasing rate of urbanization. Now, researchers reporting in PLOS Neglected Tropical Diseases February 11th have identified tap water access in densely populated neighborhoods as a strong predictor of dengue risk in the city of Delhi.

It is estimated that 3.5 billion people are at risk of dengue virus, the most widespread arbovirus. While previous attempts at controlling dengue virus with insecticides at egg-laying sites have been successful in the past, new strategies are needed to target hotspots of dengue virus transmission in urban areas.

In the new work, Olivier Telle of the French National Centre for Scientific Research (CNRS) in at Paris-Sorbonne, Richard Paul from Institut Pasteur, France, and colleagues conducted surveys across the city of Delhi to analyze social and environmental risk factors for dengue virus. They measured dengue antibodies in 2,107 individuals and mosquito larval prevalence in 18 areas within Delhi as well as socio-economic factors across the city.

Across the individuals tested in the city, 7.6% were positive for dengue virus antibodies, indicating a recent or current infection. Colonies with very poor access to tap water, with less than 61% of houses having access, were associated with a higher risk of exposure to the virus (adjusted odds ratio 4.69, 95% CI 2.06-10.67) and were the only type of area to register dengue cases between epidemics. However, despite relatively low mosquito densities, wealthy colonies had a higher risk of recent infection than intermediary colonies (aOR 2.92, 95% CI 1.26-6.72), likely reflecting the import of dengue virus by commuters coming into the high income areas during the day.

“Improved access to tap water could lead to a reduction in dengue, not only for those directly affected but for the general population,” the researchers say. “Targeted intervention through mosquito control in winter in the socially disadvantaged areas could offer a rational strategy for optimizing control efforts.”

Journal Reference:

  1. Olivier Telle, Birgit Nikolay, Vikram Kumar, Samuel Benkimoun, Rupali Pal, BN Nagpal, Richard E. Paul. Social and environmental risk factors for dengue in Delhi city: A retrospective studyPLOS Neglected Tropical Diseases, 2021; 15 (2): e0009024 DOI: 10.1371/journal.pntd.0009024

FOR MORE INFORMATION: https://www.sciencedaily.com/releases/2021/02/210211144428.htm

Groundwater recharge rates mapped for Africa

Image result for Groundwater recharge rates mapped for Africa

Dengue virus is among growing number of mosquito-borne viruses that have adapted to spread in urban environments and are spreading with the increasing rate of urbanization. Now, researchers reporting in PLOS Neglected Tropical Diseases February 11th have identified tap water access in densely populated neighborhoods as a strong predictor of dengue risk in the city of Delhi.

It is estimated that 3.5 billion people are at risk of dengue virus, the most widespread arbovirus. While previous attempts at controlling dengue virus with insecticides at egg-laying sites have been successful in the past, new strategies are needed to target hotspots of dengue virus transmission in urban areas.

In the new work, Olivier Telle of the French National Centre for Scientific Research (CNRS) in at Paris-Sorbonne, Richard Paul from Institut Pasteur, France, and colleagues conducted surveys across the city of Delhi to analyze social and environmental risk factors for dengue virus. They measured dengue antibodies in 2,107 individuals and mosquito larval prevalence in 18 areas within Delhi as well as socio-economic factors across the city.

Across the individuals tested in the city, 7.6% were positive for dengue virus antibodies, indicating a recent or current infection. Colonies with very poor access to tap water, with less than 61% of houses having access, were associated with a higher risk of exposure to the virus (adjusted odds ratio 4.69, 95% CI 2.06-10.67) and were the only type of area to register dengue cases between epidemics. However, despite relatively low mosquito densities, wealthy colonies had a higher risk of recent infection than intermediary colonies (aOR 2.92, 95% CI 1.26-6.72), likely reflecting the import of dengue virus by commuters coming into the high income areas during the day.

“Improved access to tap water could lead to a reduction in dengue, not only for those directly affected but for the general population,” the researchers say. “Targeted intervention through mosquito control in winter in the socially disadvantaged areas could offer a rational strategy for optimizing control efforts.”

Journal Reference:

  1. Alan M MacDonald, R Murray Lark, Richard G Taylor, Tamiru Abiye, Helen C Fallas, Guillaume Favreau, Ibrahim B Goni, Seifu Kebede, Bridget Scanlon, James P R Sorensen, Moshood Tijani, Kirsty A Upton, Charles West. Mapping groundwater recharge in Africa from ground observations and implications for water securityEnvironmental Research Letters, 2021; 16 (3): 034012 DOI: 10.1088/1748-9326/abd661

FOR MORE INFORMATION: https://www.sciencedaily.com/releases/2021/02/210216083056.htm

Facts on the ground: How microplastics in the soil contribute to environmental pollution

Image result for Facts on the ground: How microplastics in the soil contribute to environmental pollution

Plastic, with its unabated global production, is a major and persistent contributor to environmental pollution. In fact, the accumulation of plastic debris in our environment is only expected to increase in the future. “Microplastics” (MP) — plastic debris <5 mm in size — are particularly problematic in this regard, owing to how easily they can be ingested by marine organisms and eventually find their way to humans. But, it is not just the marine environment that contains MP debris. Studies on agricultural soil have revealed that MPs adversely affect not only the soil quality but also the physiology of soil organisms and, in turn, the interaction between soil and plants. Still, because most studies on MPs have focused on marine environments, it is not clear how abundant MPs are in different types of soils based on the agricultural practice (a source of MP) employed. Moreover, it remains to be determined whether only external sources of MP (sewage, wastewater, and runoff water due to rain) are responsible for the soil pollution.

Scientists from Incheon National University, Korea, headed by Prof. Seung-Kyu Kim, now explore these questions in their latest study published in Journal of Hazardous Materials. “Most studies on MPs have focused on the marine environment, but substantial amounts of MPs can be generated in the agricultural environment via weathering and fragmentation of plastic products used in agricultural practices. We hoped to find out the amount of MPs in Korean agricultural soils and how they change according to different agricultural practices and environmental conditions,” says Prof. Kim.

For their study, the scientists examined four soil types corresponding to different agricultural practices: soils from outside and inside a greenhouse (GS-out and GS-in, respectively), mulching (MS), and rice field soil (RS). Of these, the former three samples represented the use of polyethylene film, while the RS sample represented little to no use of plastic. To minimize the effect of non-agricultural sources of MP, scientists collected the samples from rural farmlands during the dry season. They only considered MPs in the size range of 0.1-5 and classified them as per their shapes: fragment (uneven), sheet (thin an even), spherule (round), and fiber (thread-like).

As expected, scientists found the highest average MP abundance in GS-in and GS-out (GS-in > GS-out), but surprisingly, they found the lowest MP content in MS rather than RS. Further, they found that among the different shapes of MPs, fragments dominated GS-in; fibers, GS-out and MS; and sheets, RS. Interestingly, all soils except GS-in had a major contribution from sheets, which hinted towards potential internal sources of fragment-type MPs within greenhouses.

Scientists also observed an interesting trend regarding MP size distribution in the soil samples. They found that, unlike GS-out, MS, and RS (which showed MP abundance only for a range of sizes), GS-in showed an increasing abundance for progressively smaller sizes. They attributed this to the absence of “environmental fate effect,” causing the removal of MPs by surface-runoff, infiltration, and wind in the GS-in samples. Prof. Kim explains, “Contrary to previous studies which stress on MPs originating mostly from external sources, our study reveals that MPs in agricultural soil can come from external as well as internal sources, and that their concentration and sizes can be strongly affected by environmental conditions,”

These findings can contribute to an enhanced understanding of the role of agricultural environment as an MP source. Hopefully, assessing potential risks of MPs in agricultural soils and establishing efficient management strategies can help us to reduce the threat from MPs.

FOR MORE INFORMATION: www.sciencedaily.com/releases/2021/02/210211171119.htm

Materials from Incheon National University

Flooding in the Columbia River basin expected to increase under climate change

Image result for Flooding in the Columbia River basin expected to increase under climate change

The Columbia River basin will see an increase in flooding over the next 50 years as a result of climate change, new modeling from Oregon State University indicates.

The magnitude of flooding — the term used to describe flooding severity — is expected to increase throughout the basin, which includes the Columbia, Willamette and Snake rivers and hundreds of tributaries. In some areas, the flooding season will expand, as well.

“The flood you’re used to seeing out your window once every 10 years will likely be larger than it has been in the past,” said the study’s lead author, Laura Queen, a research assistant at OSU’s Oregon Climate Change Research Institute.

The findings are based on natural river conditions and do not take into account potential flood control measures, including dams, but the increases are significant nonetheless, said study co-author Philip Mote, a professor in the College of Earth, Ocean, and Atmospheric Sciences and dean of the Graduate School at OSU.

“We don’t know how much of this increased flood risk can be managed through mitigation measures until we study the issue further,” Mote said. “But managing a 30% to 40% increase, as is predicted for many areas, is clearly beyond our management capabilities.”

The findings were published recently in the journal Hydrology and Earth System Science. Co-authors are David Rupp of the Oregon Climate Change Research Institute and Oriana Chegwidden and Bart Nijssen of the University of Washington.

The study emerged out of Queen’s work on her honors thesis as an undergraduate in the University of Oregon’s Robert D. Clark Honors College. Queen, a Corvallis native, continued the work at OCCRI and is now enrolled in a doctoral program at Victoria University of Wellington in New Zealand.

The goal of Queen’s research was to better understand how flooding in the Columbia River basin might change as the planet warms. The Columbia River drains much of the Pacific Northwest, including portions of seven states and British Columbia. It has the fourth-largest streamflow volume in the United States.

The Pacific Northwest has a history of costly and disruptive flooding. The largest flood in modern history occurred in late spring 1948 when flooding from the Columbia River destroyed the city of Vanport, Oregon, displacing more than 18,500 people. Floods on the Chehalis River in 2007 and 2009 closed Interstate 5 in Washington and floods along the Willamette River in 1996 and 2019 caused hundreds of millions of dollars in damage.

Queen ran simulations using hydrology models and a previously collected set of streamflow data for 396 sites throughout the Columbia River basin and other watersheds in western Washington. The data included a 50-year window from the past, 1950-1999, as well as a 50-year window of expected streamflows in the future, 2050 to 2099, that was developed using several different climate models.

Previous studies predicting future streamflows showed mixed results, but the results of this new analysis were clear and surprising, Mote said.

“This was the best and most complete set of data,” he said. “It shows that the magnitude of one-, 10- and 100-year floods is likely go up nearly everywhere in the region. These are profound shifts.”

The Willamette River and its tributaries are expected to see the biggest increase in flooding magnitude, with 50% to 60% increases in 100-year floods. The streamflows are expected to be smaller downstream and grow larger upstream.

On the Snake River, streamflows will grow larger as they move downstream until they reach the confluence of the Salmon River tributary and then will drop abruptly. Parts of the Snake River will see a 40% increase in 10-year floods and a 60% increase in 100-year floods. But below the confluence with the Salmon River on the Oregon-Idaho border, the increase drops to 20% for 10-year floods and 30% for 100-year floods.

The model also suggests a significant increase in the flood season on the Snake River, which is largely concentrated in late spring now but could start as early as December or January in the future, Mote said.

One of the drivers of the change is warmer winters that will see precipitation fall more as rain instead of snow. Lower spring snowpack will lead to earlier spring streamflows in many rivers. The cold upper Columbia River basin in Canada is projected to experience little change in snowpack volume, but the snow will melt faster.

The study’s findings could have implications for flood management policy in the coming decades, Mote said. A logical next step in the research is to run the models again and include existing dams to see the role they may play in mitigating flooding.

“This work provides information and impetus for the people who manage flood risk,” he said. “We’ll need to know how much of this can be mitigated by existing flood control.”

FOR MORE INFORMATION: Materials from Oregon State University