The study location, Janssand, at low tide. The tidal sand flat is located in the German Wadden Sea between the island of Spiekeroog and the mainland. Credit: Olivia Bourceau, Max Planck Institute for Marine Microbiology
Reactive oxygen species—very reactive molecules containing oxygen—have a great impact on mineralization processes in tidal sandflats, finds a study now published in Nature Communications. Their investigation is thus important for understanding marine carbon cycling.
The Wadden Sea, stretching along 500 kilometers of the North Sea shore along the coasts of Denmark, Germany and the Netherlands, mostly consists of so-called intertidal permeable sediments—i.e. seafloor that is flushed by seawater in the change of tides. It is frequently visited by seabirds, marine mammals and recreationists.
But this highly dynamic habitat is also home to a plethora of microbes. They process carbon and nutrients from the seawater and fluvial inflows, making the sand a crucial site for organic matter remineralization and transforming it into an enormous purifying filter.
A perfect spot for ROS production
The frequent fluctuation between oxic and anoxic conditions (at high tide and low tide, respectively) in the sediments makes them a perfect spot for the production of reactive oxygen species (ROS). ROS are molecules that contain oxygen and are chemically very active. Their environmental role is multifaceted: ROS can be dangerous to organisms and damage cell components, but they can also be beneficial for microbial growth.
Because of their high activity, ROS are very important agents in the transformation and cycling of carbon and other substances in the environment and can thus have a great impact on the functioning of ecosystems. Nevertheless, they remain poorly studied in many habitats—amongst them the sandy flats of the Wadden Sea.
A group of scientists from the Max Planck Institute for Marine Microbiology in Bremen now took a closer look at ROS in a sandflat called Janssand in the German Wadden Sea off the island of Spiekeroog. Olivia Bourceau, Marit van Erk and their colleagues from the Microsensor Group investigated the ROS hydrogen peroxide.
“We wanted to know if there is any detectable hydrogen peroxide in the intertidal sands,” says Bourceau. “And if so, we wanted to know how this hydrogen peroxide impacts the mineralization processes, the recycling of organic matter, in these sands.”
Hydrogen peroxide impacts microbial activity
Indeed, the team around Bourceau and van Erk detected high concentrations of hydrogen peroxide in the intertidal sands. “We found that there is a fine balance between the production and degradation of hydrogen peroxide,” says co-author van Erk.
When the scientists changed the input of oxygen or removed hydrogen peroxide in experiments, that massively impacted the sand-dwelling microbes. ROS inhibited the microorganisms in the sand, thus its removal boosted microbial activity. “The amount of ROS naturally present in the sands reduced the rates of the main mineralization processes, both aerobic respiration and sulfate reduction, substantially.”
Important for carbon and nutrient cycling
Elevated ROS levels can be expected particularly during disturbance events and at oxic–anoxic interfaces—both frequently occurring in intertidal permeable sediments. The high rates of carbon and nitrogen remineralization make these sediments into huge biocatalytic filters. Any changes in ROS concentrations thus have the potential to directly impact the effectiveness of sands as such filters and the functioning of shallow water ecosystems.
Consequently, ROS may play an important and yet unappreciated role in the biogeochemistry of dynamic coastal sediments. “From our findings, we can conclude that ROS have the potential to substantially impact carbon cycling in the sediments. Understanding the controls on carbon cycling is very important for studying eutrophication and the impact of human activity on coastal systems,” Bourceau concludes.
More information:
Marit R. van Erk et al, Reactive oxygen species affect the potential for mineralization processes in permeable intertidal flats, Nature Communications (2023). DOI: 10.1038/s41467-023-35818-4
Citation:
Reactive oxygen shown to impact carbon cycling in tidal sands (2023, March 14)
retrieved 14 March 2023
from https://phys.org/news/2023-03-reactive-oxygen-shown-impact-carbon.html
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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
