PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Reliably measuring whether rivers or lakes run out of air

International study shows that freshwater polluted by fecal material can be determined more quickly and reliably using a new technique.

Reliably measuring whether rivers or lakes run out of air
2021-04-14
(Press-News.org) When wastewater from villages and cities flows into rivers and lakes, large quantities of fats, proteins, sugars and other carbon-containing, organic substances wind up in nature together with the fecal matter. These organic substances are broken down by bacteria that consume oxygen. The larger the volume of wastewater, the better the bacteria thrive. This, however, means the oxygen content of the water continues to decrease until finally the fish, muscles or worms literally run out of air. This has created low-oxygen death zones in many rivers and lakes around the world.

No gold standard for measurements until now

In order to measure how heavily the waters are polluted with organic matter from feces, government bodies and environmental researchers regularly take water samples. One widely used measurement method uses a chemical reaction to determine the content of organic substances. As an international team of scientists now shows, this established method provides values from which the actual degree of the water pollution can hardly be derived. Prof. Helmuth Thomas, Director of Hereon's Institute of Carbon Cycles is also a contributor to the study, which has now been published in the scientific journal Science Advances. "In the paper, we are therefore also introducing a new method for making the measurements much more reliable in the future," he says.

Using the conventional measurement method, water samples are mixed with the chemicals permanganate or dichromate. These are especially reactive and break down all organic substances in a short time. The quantity of consumed permanganates or dichromates can then be used to determine how much organic substance was contained in the water sample. Experts refer to this measurement as "chemical oxygen demand", COD. The problem with the COD measurements is that they do not differentiate between the organic substances that wind up in the water with the sewage, and those that arise naturally--such as lignin and humic acids--which are released when wood decays. This means that the water pollution can hardly be distinguished from the natural content of organic substances. "For the Han River in South Korea, for example, we have shown that the pollution with organic substances from wastewater in the past twenty-five years has decreased. The COD measurements, however, still show high values as they were before," says Helmuth Thomas, "because here the natural substances make up a large portion of the organic matter in the water."

Complicated biological analysis

But how can the actual pollution be measured more reliably? A biological measurement method has been established here for decades, but it is much more complex than the COD method and is therefore used more seldomly by government bodies and research institutions. In this case, a water sample is taken from the river or lake and the oxygen content of the water is measured as an initial value. Another "parallel sample" is immediately sealed airtight. Then this water sample rests for five days. During this time, the bacteria break down the organic substance, whereby they gradually consume the oxygen in the water. After five days, the container is opened and the oxygen is measured. If the water contains a great deal of organic matter, then the bacteria were particularly active. The oxygen consumption was then correspondingly high. Experts refer to the "biological oxygen demand" (BOD) in this measurement. "The BOD measurement is far more precise than the COD because the bacteria preferentially break down the small organic molecules from the wastewater but leave the natural ones, such as lignin, untouched," says Thomas. Nevertheless, the BOD measurement has its disadvantages, too. On the one hand, the BOD measurement takes five days, while the COD value is available after a few minutes. On the other, while filling, storing and measuring the water samples, meticulous care must be taken to ensure that no oxygen from the ambient air winds up in the sample and falsifies the measurement value. "Only a few people with a great deal of laboratory experience have mastered how to entirely handle the BOD measurement," says Thomas. "Therefore, government bodies and researchers even today still prefer the COD despite its greater uncertainties."

Faster and more reliable method

Helmuth Thomas and his team are therefore introducing an alternative method that improves on the conventional BOD measurement. The advantage to the method is that only one water sample is necessary, which is immediately sealed and the oxygen consumption is measured without interfering with the sample. It is therefore unnecessary to open the sample after five days again to measure the oxygen content. This prevents the sample from coming into contact with atmospheric oxygen again. With the new approach, an optical fiber is inserted into the sample vessel as soon as the water sample is filled. Through this fiber, the oxygen content can be continuously measured directly in the sample using optical effects. Thomas says, "We can measure the oxygen content non-stop and obtain a far more precise picture of the oxygen consumption by the bacteria." First tests have shown that a meaningful result is already available after about forty-eight hours, something that considerably accelerates the BOD measurement. All in all, the optical method makes the BOD measurements not only more reliable, but also faster. Helmuth Thomas assumes that the new method in the coming years therefore will be established as the new standard, which will replace both the COD as well as the classic BOD measurements. In the future, for example, it will be possible to determine more reliably than before whether water pollution control measures are actually successful.

INFORMATION:


[Attachments] See images for this press release:
Reliably measuring whether rivers or lakes run out of air

ELSE PRESS RELEASES FROM THIS DATE:

Grave goods show gendered roles for Neolithic farmers

2021-04-14
Grave goods, such as stone tools, have revealed that Neolithic farmers had different work-related activities for men and women. Researchers at the University of York analysed 400 stone objects found in graves at cemetery sites across Europe and noted there were differences in size, weight, and raw material dependent on whether the body was a male or a female. Archaeologists had previously thought that polished stone tools in this period were used for woodworking, but analysis now shows a much wider range of tasks, with different activities for men and women. The tools found in female graves were most likely used for the working of animal skins and hide, and tools for the men were associated with hunting ...

Researchers establish intracellular interaction network in breast cancer

Researchers establish intracellular interaction network in breast cancer
2021-04-14
Researchers at HSE University have identified the genes that play a crucial role in breast cancer metastasis. The results of the study were published in the journal PLOS ONE. Every human cell includes a huge number of various molecules: DNA, RNA, proteins, etc. One of the essential classes of molecules that interact with each other are microRNAs, along with their target genes and transcription factors. MicroRNAs are small molecules, which can directly reduce the concentration (expression) of target genes, while transcription factors are able to both increase and reduce the expression of ...

Lower COVID-19 rates seen in US states with higher adherence to mask wearing

2021-04-14
A new state-by-state analysis shows a statistical association between high adherence to mask wearing and reduced rates of COVID-19 in the U.S. Charlie Fischer and colleagues at the Boston University School of Public Health in Massachusetts present these findings in the open-access journal PLOS ONE on April 14. During the COVID-19 pandemic, different states have enacted different policies on mask wearing, with some states having no mask requirements and others requiring masks in all public spaces. Understanding the link between mask wearing and COVID-19 rates could help inform policies to mitigate stress on healthcare systems, economic instability, and death. To help clarify the effects of mask wearing, Fischer and colleagues examined publicly ...

Triple combination therapy shows promise against a rare deadly asbestos cancer

Triple combination therapy shows promise against a rare deadly asbestos cancer
2021-04-14
Combining immune-boosting drugs with radiation and surgery increased the survival and anticancer immune response in mouse models of mesothelioma in preclinical research by Princess Margaret Cancer Centre researchers. In a series of exciting experiments using mouse models of mesothelioma cancer, researchers found that combining two immunotherapy drugs can amplify the anti-tumour response first triggered by a short course of radiation, conferring long-lasting control and resistance against cancer. These response rates are improved further by adding surgery to remove the remaining tumour. Better treatments are urgently needed for mesothelioma patients, as ...

Study identifies ways women increase their sexual pleasure during vaginal penetration

Study identifies ways women increase their sexual pleasure during vaginal penetration
2021-04-14
INDIANAPOLIS, IN AND BERKELEY, CA (April 14, 2021) - Researchers from Indiana University School of Medicine and OMGYES have conducted the first-ever, large-scale, nationally representative study focused on women's techniques for increasing their own pleasure from vaginal penetration. The findings, published today in the scientific journal, PLOS ONE, identify and name four distinct methods: Angling, Pairing, Rocking and Shallowing. The research was led by Dr. Devon J. Hensel, Associate Professor of Research at Indiana University School of Medicine, and Dr. Christiana von Hippel, an OMGYES Research Scientist. "For the first time, we have ...

Tiny wireless implant detects oxygen deep within the body

2021-04-14
Berkeley -- Engineers at the University of California, Berkeley, have created a tiny wireless implant that can provide real-time measurements of tissue oxygen levels deep underneath the skin. The device, which is smaller than the average ladybug and powered by ultrasound waves, could help doctors monitor the health of transplanted organs or tissue and provide an early warning of potential transplant failure. The technology, created in collaboration with physicians at the University of California, San Francisco, also paves the way for the creation of a variety of miniaturized sensors that could track other key biochemical markers in the body, ...

Massive fragment screen points way to new SARS-CoV-2 inhibitors

Massive fragment screen points way to new SARS-CoV-2 inhibitors
2021-04-14
New research published in Science Advances provides a template for how to develop directly-acting antivirals with novel modes of action, that would combat COVID-19 by suppressing the SARS-CoV-2 viral infection. The study focused on the macrodomain part of the Nsp3 gene product that SARS-CoV-2 uses to suppress the host cell's natural antiviral response. This part of the virus's machinery, also known as Mac1, is essential for its reproduction: previous studies have shown that viruses that lack it cannot replicate in human cells, suggesting that blocking ...

New in the Hastings Center Report, March-April 2021

2021-04-14
"Family clustering is a confirmed phenomenon associated with Covid-19, and harrowing stories of this disease ravaging families continue to be reported," a new article explains in the March-April issue of the Hastings Center Report. In one extreme example, 28 extended family members in California reportedly tested positive for Covid-19. Two of the family members who quarantined together required hospitalization, and one of them died from the infection. In family clustering cases, multiple loved ones may suffer from the symptoms of Covid-19 and be hospitalized, in quarantine, or recovering; and family ...

Researchers map brain regions responsible for intoxicating effects of alcohol

2021-04-14
The slurred speech, poor coordination, and sedative effects of drinking too much alcohol may actually be caused by the breakdown of alcohol products produced in the brain, not in the liver as scientists currently think. That is the finding of a new study led by researchers from the University of Maryland School of Medicine (UMSOM) and the National Institute on Alcohol Abuse and Alcoholism. It was published recently in the journal Nature Metabolism and provides new insights into how alcohol may affect the brain and the potential for new treatments to treat alcohol misuse. It is well known that the liver is the major organ ...

Photonic MEMS switches going commercial

Photonic MEMS switches going commercial
2021-04-14
One of the technical challenges the current data revolution faces is finding an efficient way to route the data. This task is usually performed by electronic switches, while the data itself is transferred using light confined in optical waveguides. For this reason, conversion from an optical to an electronic signal and back-conversion are required, which costs energy and limits the amount of transferable information. These drawbacks are avoidable with a full optical switch operation. One of the most promising approaches is based on microelectromechanical systems (MEMS), thanks ...

LAST 30 PRESS RELEASES:

Genetic causes of cerebral palsy uncovered through whole-genome sequencing

Modesty and boastfulness – perception depends on usual performance

Do sweeteners increase your appetite? New evidence from randomised controlled trial says no 

Women with obesity do not need to gain weight during pregnancy, new study suggests

Individuals with multiple sclerosis face substantially greater risk of hospitalisation and death from COVID-19, despite high rates of vaccination

Study shows obesity in childhood associated with a more than doubling of risk of developing multiple sclerosis in early adulthood

Rice Emerging Scholars Program receives $2.5M NSF grant to boost STEM education

Virtual rehabilitation provides benefits for stroke recovery

Generative AI develops potential new drugs for antibiotic-resistant bacteria

Biofuels could help island nations survive a global catastrophe, study suggests

NJIT research team discovering how fluids behave in nanopores with NSF grant

New study shows association of historical housing discrimination and shortfalls in colon cancer treatment

Social media use may help to empower plastic surgery patients

Q&A: How to train AI when you don't have enough data

Wayne State University researchers uncover potential treatment targets for Zika virus-related eye abnormalities

Discovering Van Gogh in the wild: scientists unveil a new gecko species

Small birds spice up the already diverse diet of spotted hyenas in Namibia

Imaging detects transient “hypoxic pockets” in the mouse brain

Dissolved organic matter could be used to track and improve the health of freshwaters

Indoor air quality standards in public buildings would boost health and economy, say international experts

Positive associations between premenstrual disorders and perinatal depression

New imaging method illuminates oxygen's journey in the brain

Researchers discover key gene for toxic alkaloid in barley

New approach to monitoring freshwater quality can identify sources of pollution, and predict their effects

Bidirectional link between premenstrual disorders and perinatal depression

Cell division quality control ‘stopwatch’ uncovered

Vaccine protects cattle from bovine tuberculosis, may eliminate disease

Andrew Siemion to receive the SETI Institute’s 2024 Drake Award

New study shows how the Crimean-Congo hemorrhagic fever virus enters our cells

Neoadjuvant chemotherapy proves effective for locally advanced penile squamous cell carcinoma

[Press-News.org] Reliably measuring whether rivers or lakes run out of air
International study shows that freshwater polluted by fecal material can be determined more quickly and reliably using a new technique.