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LOS ANGELES, June 17 (Xinhua) -- The size of low-oxygen zones created by respiring bacteria is extremely sensitive to changes in depth caused by oscillations in climate, thus posing a distant threat to marine life, a new study suggests."The growth of low-oxygen regions is cause for concern because of the detrimental effects on marine populations -- entire ecosystems can die off when marine life cannot escape the low- oxygen water," said lead researcher Curtis Deutsch, assistant professor of atmospheric and oceanic sciences at University of California, Los Angeles."There are widespread areas of the ocean where marine life has had to flee or develop very peculiar adaptations to survive in low- oxygen conditions," Deutsch said in the study to be published in an upcoming print edition of the journal Science.A team led byDeutsch used a specialized computer simulation to demonstrate for the first time that fluctuations in climate can drastically affect the habitability of marine ecosystems.The study also showed that in addition to consuming oxygen, marine bacteria are causing the depletion of nitrogen, an essential nutrient necessary for the survival of most types of algae."We found there is a mechanism that connects climate and its effect on oxygen to the removal of nitrogen from the ocean," Deutsch said. "Our climate acts to change the total amount of nutrients in the ocean over the timescale of decades."Low-oxygen zones are created by bacteria living in the deeper layers of the ocean that consume oxygen by feeding on dead algae that settle from the surface. Just as mountain climbers might feel adverse effects at high altitudes from a lack of air, marine animals that require oxygen to breathe find it difficult or impossible to live in these oxygen-depleted environments, Deutsch said.Sea surface temperatures vary over the course of decades through a climate pattern called the Pacific Decadal Oscillation, during which small changes in depth occur for existing low-oxygen regions, Deutsch said. Low-oxygen regions that rise to warmer, shallower waters expand as bacteria become more active; regions that sink to colder, deeper waters shrink as the bacteria become more sluggish, as if placed in a refrigerator."We have shown for the first time that these low-oxygen regions are intrinsically very sensitive to small changes in climate," Deutsch said in remarks published Friday by the American Association for the Advancement of Science on its website. "That is what makes the growth and shrinkage of these low-oxygen regions so dramatic."Molecular oxygen from the atmosphere dissolves in sea water at the surface and is transported to deeper levels by ocean circulation currents, where it is consumed by bacteria, Deutsch said."The oxygen consumed by bacteria within the deeper layers of the ocean is replaced by water circulating through the ocean," he said. "The water is constantly stirring itself up, allowing the deeper parts to occasionally take a breath from the atmosphere."A lack of oxygen is not the only thing fish and other marine life must contend with, according to Deutsch. When oxygen is very low, the bacteria will begin to consume nitrogen, one of the most important nutrients that sustain marine life."Almost all algae, the very base of the food chain, use nitrogen to stay alive," Deutsch said. "As these low-oxygen regions expand and contract, the amount of nutrients available to keep the algae alive at the surface of the ocean goes up and down. "Understanding the causes of oxygen and nitrogen depletion in the ocean is important for determining the effect on fisheries and fish populations, he said.

DAMASCUS, Sept. 21 (Xinhua) -- The national archeological expedition recently discovered a gigantic building built with large-size hewn stones that date back to the Roman era, Syrian Arab News Agency (SANA) said Wednesday.The building, the thickness of its walls up to 1.5 meters, was found at Qumet Nibal site in the northeastern province of Raqqa, said SANA.Ibrahim Kheir Bek, head of the archeological department in the area, told SANA that the excavation unearthed a 6-meter-long entrance to the building, adding that works are still underway in the site.A day earlier, the national archeological expedition discovered a mosaic dating back to the 6th century A.D. in northeast Syria, SANA said, adding that the rectangular mosaic was found at Hwaija Halawa site on the banks of al-Assad Lake in Raqqa province.Ayham al-Fakhri, head of the national expedition, was quoted by SANA as saying that the expedition uncovered 58 square meters of the mosaic with various colorful geometric shapes.

BERLIN, June 1 (Xinhua) -- Germany's disease control center reported on Wednesday 365 new cases of the fatal enterohemorrhagic E. coli (EHEC), which marked a sharp rise since its outbreak in the middle of May.Twenty-five percent of the new cases involved the hemolytic- uremic syndrome (HUS), a serious complication resulting from E. coli infection that affects the blood and kidneys, Germany's Robert Koch Institute said.Until now 17 people in Europe, one in Sweden, the other in Germany have been killed by the deadly disease, while the source of the infection was still not identified.According to the data of Robert Koch Institute, at present 470 patients are suffering from HUS due to the infection, raising concerns that the death toll could be even higher in the future.Germany's Agriculture and Consumer Protection Minister Ilse Aigner defended Germany's previous alert on cucumbers from Spain on Wednesday."The fatal strain of EHEC bacteria was indeed found on Spanish cucumbers. According to the European rules, a quick warning must be sent out," she told a local TV station.Laboratory tests in Hamburg on Tuesday overthrew the previous finding that Spanish cucumbers were the sources of the outbreak.As a result of the alert, Europe and Russia imposed bans on Spanish vegetables, leaving Spanish farmers a loss of 200 million euros (287.5 million U.S. dollars) a week.Spain has expressed its intention to take possible legal actions against authorities in Hamburg and ask for compensations from Germany and the European Union.

JERUSALEM, July 25 (Xinhua) -- A new study carried out by a Tel Aviv University researcher indicates that the common backache may not only be caused by bad positions or aging, but also by your genes.Prof. Gregory Livshits of the Sackler Faculty of Medicine says that genes play a major role in back pain, especially in the lower back, and in spinal deterioration.In a decade-long project with 2,500 identical and non-identical twins, Livshits found that, in one Arab family, the same back problems appeared in all the members of the family, whether young or old.According to the study, non-identical twins were three times more likely to have back pain, while identical twins were six times more likely to have the same back problems.Livshits believes the discovery of the link between back pains and genes could lead to much better treatment.The research was developed in collaboration with a team of scientists at Kings College, London, led by Prof. Tim Spector and Dr. Fran Williams and was recently published in the journal " Annals of the Rheumatic Diseases."In order to better investigate the genetic causes for one of the world most common pains, Livshits and his colleagues hope to put together an international consortium of research groups.

BEIJING, Aug. 13 (Xinhua) -- The quality of the products China exported to the European Union (EU) improved during the first half of this year due to strict quality control measures, according to quality control authorities.The number of quality complaints made by the EU regarding Chinese imports declined by 45 percent in the first half of 2011, according to the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).The administration attributed the improved quality to its nationwide crackdown on counterfeited and substandard products.The administration launched a nationwide quality checkup in the first half of this year. Of the 4,815 batches of products that the quality control authorities checked between January and June, just 9.4 percent failed quality tests, 1.7 percentage points lower than that of the same period of last year, according to the administration.A total of 218,000 counterfeiting cases have been investigated so far this year, involving goods worth a total of 9.5 billion yuan (1.49 billion U.S. dollars), the administration said.

来源：资阳报