Three major hydrological flow paths in the riparian zone were inferred by correlating dynamics of the organic chemistry, as well as inorganic nitrogen (ammonium and nitrate), between sampling points. Most probably the DFAAs' lability resulted in their almost complete immobilization within the streambed during microporous discharge of catchment runoff through the streambed. Although their mean concentrations were also higher in soil waters (168.2 nmol l −1) than in the stream (113.9 nmol l −1), this was not a consistent trend. Total DFAA concentrations were <0.3% of the DOC measured. This represents an average carbon input of some 2500 g C m −2 year −1 to the stream, indicating the quantitative importance of DOC in riparian soil waters to stream productivity. DOC, which as a whole is relatively refractory, was contrasted with the labile dissolved free amino acids (DFAAs).ĭOC distributions in riparian soil waters showed little temporal or spatial consistency, but concentrations almost always exceeded those in the stream (mean = 9.4 and 2.1 mg l −1, respectively). Climate change impacting Gulf Stream changeĪmong the factors affecting the current are the melting of the Greenland ice sheet, melting of Arctic sea ice, and an overall enhanced precipitation and river runoff.Conflicting views on the potential importance of soil water as a source of dissolved organic carbon (DOC) in headwater streams are addressed by comparing organic chemistries of soil waters in the riparian zone with an adjacent stream at an upland site in mid-Wales during one year. "The loss of dynamical stability would imply that the AMOC has approached its critical threshold," Boers wrote, which could lead the circulation system to collapse. They concluded that the weakening of the last century is likely to be associated with a loss of stability. Researchers analyzed the sea-surface temperature and salinity patterns of the Atlantic Ocean. Researchers said in the study that the difference matters. It had not been clear whether the weakening is due to a change in circulation or a loss of stability. Niklas Boers of the Potsdam Institute for Climate Impact Research (PIK) in Germany, wrote in the journal that the AMOC system was found to be weaker than at any time in the past 1,000 years. "The AMOC may have evolved from relatively stable conditions to a point close to a critical transition," they concluded.Ī collapse of the system would substantially cool Europe and have a strong impact on the tropical monsoon systems. "Significant early-warning signals are found in eight independent AMOC indices, based on observational sea-surface temperature and salinity data from across the Atlantic Ocean basin," researchers wrote in the study's abstract. As the AMOC redistributes heat, it influences weather patterns globally. It transports that warm water from the tropics near to the ocean's surface, while it pushes cold water southwards and deeper below the surface. In the study, published on Thursday in the journal Nature Climate Change, researchers focused on the Atlantic Meridional Overturning Circulation (AMOC). The large system of ocean currents, which is part of the Gulf Stream, transports warm water from the tropics northwards into the North Atlantic. The Atlantic Ocean's system of currents, which impact the Northern Hemisphere's climate, could be weakening and result in major changes to the world's weather, a new scientific study warned.
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