Ocean University of China

A collaborative research team has recently revealed that rotifers, a kind of microscopic zooplankton common in both fresh and ocean water around the world, are able to chew apart microplastics, breaking them down into even smaller, and potentially more dangerous, nanoplastics -- or particles smaller than one micron. Each rotifer can create between 348,000 -- 366,000 per day, leading to uncountable swarms of nanoparticles in our environment. A collaborative research team lead by the University of Massachusetts Amherst has recently revealed that rotifers, a kind of microscopic zooplankton common in both fresh and ocean water around the world, are able to chew apart microplastics, breaking them down into even smaller, and potentially more dangerous, nanoplastics -- or particles smaller than one micron. Each rotifer can create between 348,000 - 366,000 per day, leading to uncountable swarms of nanoparticles in our environment. In China's Poyang Lake, the country's largest freshwater lake, the researchers calculated that rotifers were creating 13.3 quadrillion particles every single day. The research was recently reported in Nature Nanotechnology. It is well known that plastic is an incredibly durable material, which can take up to 500 years to decompose. As plastic bottles, packaging and parts get older, teeny pieces of them break off. These microplastics have been found in every corner of the globe, from the top of Mount Everest to the depths of the Mariana Trench, and, according to recent reports, they are in many humans' blood and heart tissue. The problem is that microplastics pose an as-of-yet unknown risk to the environment and to human health, and they're altering ecosystems throughout the world. The smaller the plastic particle, the more easily they spread and the more of them they are. Each individual microplastic could theoretically be broken down into 1,000,000,000,000,000 nanoplastic particles. Smaller size also means more surface area, which means they are more reactive and potentially even more harmful to the health of humans and other living beings than microplastics. While there has been much attention given to microplastics, there has been far little interest in studying nanoplastics, particularly in how they're generated, which means we don't really know how many nanoplastics might be out there. "Humans produce enormous amounts of plastics, and yet we don't have an effective way of recycling them," says Baoshan Xing, University Distinguished Professor of Environmental & Soil Chemistry at UMass Amherst's Stockbridge School of Agriculture and the paper's senior author. "We began to wonder about nanoplastics and especially how they're produced." In part, they're produced through physical and chemical processes: sunlight breaks plastics down, and waves grind bits of plastic against rocks, beaches and other trash floating in the ocean. But Xing and his colleagues wondered what role living creatures might play in the creation of microplastics, especially after learning that Antarctic krill seem to be able to break microplastics down into smaller particles. Xing and his colleagues were particularly curious about rotifers, of which there are around 2,000 different species worldwide. "Whereas Antarctic krill live in a place that is essentially unpopulated," says Xing, "we chose rotifers in part because they occur throughout the world's temperate and tropical zones, where people live." They are abundant -- one of the lakes other researchers reported had approximately 23,000 individual rotifers in every liter of water. And rotifers also have a specialized masticatory apparatus -- "teeth" -- that the team hypothesized could grind microplastics into smaller particles. After exposing both marine and freshwater species of rotifers to a variety of different plastics of different sizes, they found that all rotifers could ingest microplastics of up to 10 micrometers in size, break them down and then excrete thousands of nanoplastics back into the environment. They estimated that rotifers could produce 13.3 quadrillion nanoparticles every day in Poyang Lake. Scale this up to all of the ocean and fresh bodies of water where both microplastics and rotifers are present, and the number of nanoplastic particles created every day is mind boggling. "We show for the first time the ubiquitous fragmentation of microplastics by rotifers," says Jian Zhao, professor of environmental science and engineering at the Ocean University of China and the paper's lead author. "This is a newly discovered route to produce and generate nanoplastics in both freshwater and seawater system worldwide, in addition to well-known physical and photochemical fragmentations. This finding is helpful for accurately evaluating the global flux of nanoplastics. In addition, it is known that nanoplastics can not only be potentially toxic to various organisms, they can also serve as carriers for other contaminants in the environment. Furthermore, the release of chemical additives in the plastic can be enhanced during and after the fragmentation." "Our work is just the first step," adds Xing. "We need to look at other organisms on the land and in water for biological fragmentation of microplastics and collaborate with toxicologists and public health researchers to determine what this plague of nanoplastics is doing to us."

Marine virologists analyzed sediment from the Mariana Trench, the deepest place on Earth, and identified a new bacteriophage. The Mariana Trench, the deepest place on Earth, plunges nearly 11,000 meters at its lowest point on the floor of the Pacific Ocean. Life persists in the deep and cold darkness, and "wherever there's life, you can bet there are regulators at work," said marine virologist Min Wang, Ph.D, at the Ocean University of China, in Qingdao. "Viruses, in this case." This week in Microbiology Spectrum, Wang and an international group of researchers report the discovery of a new virus isolated from sediment brought up from a depth of 8,900 meters. The virus is a bacteriophage, or a virus that infects and replicates inside bacteria, and bacteriophages are believed to be the most abundant life forms on the planet. "To our best knowledge, this is the deepest known isolated phage in the global ocean," said Wang. The newly found phage infects bacteria in the phylum Halomonas, which are often found in sediments from the deep seas and from hydrothermal vents, geyser-like openings on the seafloor that release streams of heated water. Wang said the group's analysis of the viral genetic material points to existence of a previously unknown viral family in the deep ocean, as well as new insights into the diversity, evolution and genomic features of deep-sea phages and phage-host interactions. In previous work, the researchers have used metagenomic analysis to study viruses that infect bacteria in the order Oceanospirallales, which includes Halomonas. For the new study, Wang's team looked for viruses in bacterial strains collected and isolated by a team led by marine virologist Yu-Zhong Zhang, Ph.D, also at the Ocean University of China, in Qingdao. Zhang's research explores microbial life in extreme environments, including polar regions and the Mariana Trench. The genomic analysis of the new virus, identified as vB_HmeY_H4907, suggests that it is distributed widely in the ocean and has a similar structure to its host. Wang said the study points to new questions and research areas focused on the survival strategies of viruses in harsh, secluded environments -- and how they co-evolve with their hosts. The new virus is lysogenic, which means it invades and replicates inside its host, but usually without killing the bacterial cell. As the cell divides, the viral genetic material is also copied and passed on. In future studies, Wang said, the group plans to investigate the molecular machinery that drives interactions between deep-sea viruses and their hosts. They're also searching for other new viruses in extreme places, "which would contribute to broadening our comprehension of the virosphere," Wang said. "Extreme environments offer optimal prospects for unearthing novel viruses."

Hadal trenches, with their deepest locations situated in the so-called hadal zone, the deepest parts of the ocean in water depth >6km, are the least-explored environment on Earth, linking the Earth's surface and its deeper interior. An international team conducting deep-subsurface sampling in a hadal trench at high spatial resolution has revealed exciting insights on the carbon cycling in the trench sediment. Hadal trenches, with their deepest locations situated in the so-called hadal zone, the deepest parts of the ocean in water depth >6km, are the least-explored environment on Earth, linking the Earth's surface and its deeper interior. For the first time, an international team conducted deep-subsurface sampling in a hadal trench at high spatial resolution during International Ocean Discovery Program (IODP) Expedition 386 "Japan Trench Paleoseismology." The first major results of this Expeditions reveal exciting insights on the carbon cycling in the trench sediment and is now published in Nature Communications. The Japan Trench is located on the "Pacific Ring of Fire," a region of special interest in earthquake and deep-water research. "It is here that oceanic plates bend, form ultra-deep-water trenches and move below overriding plates in so-called subduction zones, while accumulating long-term global plate tectonic strain," says Dr. Ken Ikehara from National Institute of Advanced Industrial Science and Technology, Japan, and co-chief scientist of IODP Expedition 386. "This energy is released cataclysmically during so-called megathrust earthquakes, like it happened in 2011 during the devastating Tohoku-oki Earthquake." Earthquake-related seafloor deformation and shaking can remobilize large amounts of sediments and fresh organic carbon that is subsequently transferred by gravity flows into the terminal sink of hadal trench basins. In order to study the long-term history of megathrust earthquakes and investigate the roles of earthquakes in the ultra-deep-water environment, the IODP Expedition 386 team has collected and analysed 58 sediment cores taken from holes cored up to 37.82 meters deep in the sea bed at 15 sites along the 500-km-long trench axis. "These operational expedition achievements of successful deep-subsurface sampling at water depths between 7445-8023 m below sea level set two new records in over 50 years of scientific ocean drilling and coring," says Prof. Michael Strasser from the University of Innsbruck and co-chief scientist of the IODP Expedition 386. "We have cored the deepest water site at a water depth of 8023 meters and recovered the deepest sub-sea level sample from 8060.74 meters below sea level." Analyses of such unprecedented samples and research led by Prof. Rui Bao at Ocean University of China has found large amount of labile dissolved carbon stored in the sediment interstitial water. The dissolved carbon storage implies active organic carbon remineralization in the hadal trenches that is much greater than in other deep-water environments of the open ocean. Using advanced radiocarbon techniques, the team discovered aging and accumulation of the dissolved organic and inorganic carbon in the deep subsurface sediments. "These are exciting results, because these dissolved carbon fractions may have great impacts on the deep carbon cycle as they are buried still deeper into the trench sediments and the subduction zone," said Mengfan Chu, PhD candidate at Ocean University of China, and lead-author of the study now published in Nature Communications. Active microbial-mediated dissolved carbon cycling in the deep subsurface sediments A comprehensive geochemistry investigation on the sediment interstitial water based on IODP Expedition 386 results supports the hypothesis. Huge storages of methane are found in sediments along the whole Japan Trench, together with other outstanding geochemical characteristics of the interstitial water. This points to intensive microbial methanogenesis in the hadal trenches and is interpreted as an enhancement effect of repeated large earthquakes along the subduction zone. Through increasing organic carbon fluxes and regulating the physical and chemical characteristics of the sediment deposits, earthquakes serve as a powerful modulator in the trench carbon cycle and the deep biosphere metabolisms in these extreme environments. "These discoveries provide strong evidence that the hadal trenches are not 'tranquil' deep-sea environments as previously considered. We're excited to say that more discoveries about the hadal trench carbon cycle are bound to be made in the future." says Prof. Rui Bao. "For instance, in our study we also report the occurrence of authigenic carbonates in the deep subsurface of Japan Trench sediments, which suggests active transformation of carbon between its different forms (sedimentary, dissolved, gaseous and mineral) and implies that hadal trench environments host dynamic carbon cycling, which link the Earth's surface and its deeper interior along subduction zones, providing great opportunities for future studies." Further perspectives of research in the Japan Trench The new discoveries of a dynamic carbon cycle in the Japan trench represent the first major scientific achievement resulting from the novel high temporal and high spatial resolution subsurface sampling and investigation of hadal oceanic trench achieved by Expedition 386 in the Japan Trench. Alongside this first scientific IODP-Expedition 386 related publication, the preliminary results of the entire expedition are now released by IODP. Along with the new perspectives and further potential to advance our understanding of deep-sea elemental cycles and their influence on hadal environments, samples and data from this expedition also reveal fascinating event records ranging back more than 24000 years. This enables now-ongoing research and new perspectives for the discussion on long-term recurrence and hazards of major megathrust earthquakes. Thirty-six scientists with expertise in different geoscience disciplines from Austria, Australia, China, Finland, France, Germany, India, Japan, UK, and the United States are now conducting further researches using the samples acquired by the advanced ocean drilling platform of IODP. More substantial scientific advances are expected to push the frontier of ultra-deep-water, subduction zone and earthquake researches. The International Ocean Discovery Program (IODP) is a publicly-funded international marine research program supported by 21 countries, which explores Earth's history and dynamics as recorded in seafloor sediments and rocks. IODP Expedition 386 -- Japan Trench Paleoseismology -- was jointly implemented by the European Consortium for Ocean Research Drilling (ECORD) and the Institute for Marine-Earth Exploration and Engineering (MarE3) within the Japan Agency for Marine-Earth Science and Technology (JAMSTEC).