After completing one of the longest running experiments ever done on a lake, researchers from the University of Alberta, University of Minnesota and the Freshwater Institute, contend that nitrogen control, in which the European Union and many other jurisdictions around the world are investing millions of dollars, is not effective and in fact, may actually increase the problem of cultural eutrophication.

Grand Beach on Lake Winnipeg undergoing eutrophication.  Image by Lori Volkart.

The dramatic rise in cultural eutrophication—the addition of nutrients to a body of water due to human activity that often causes huge algal blooms, fish kills and other problems in lakes throughout the world—has resulted from increased deposits of nutrients to lakes, largely from human sewage and agricultural wastes.

For 37 years researchers looked at Lake 227, a small lake in the Canadian Shield at the Experimental Lakes Area (ELA) in Ontario, Canada, and examined the best ways to control the cultural eutrophication process of lakes by varying the levels of phosphorous and nitrogen added to the lake.

"What we found goes against the practices of the European Union and many scientists around the world," said David Schindler, professor of ecology at the University of Alberta and one of the leading water researchers in the world. "Controlling nitrogen does not correct the polluted lakes, and in fact, may actually aggravate the problem and make it worse."

Spanish and German researchers have carried out a collaborative study that shows how during the last glacial period, small variations in the surface winds could have induced significant changes in the oceanic currents of the North Atlantic, and could even have played a role in the abrupt climate change that occurred at the time.

The North Atlantic circulation is part of thermohaline circulation that globally affects oceanic waters. Photograph: Andrew Ryzhkov.

Scientists from the Complutense University of Madrid (UCM) and the Potsdam-Institute for Climate Impact Research in Germany have carried out a study which identifies small alterations in the superficial sea winds as the factors with a key role in the abrupt climatic change that occurred over the last glacial period whose origin is not yet fully understood. The research has been published in the prestigious journal Geophysical Research Letters receiving a special mention from the American Geophysical Union.

This study, carried out by researchers Marisa Montoya and Anders Levermann, concluded that there is a precise point from which a small variation in the speed of sea winds corresponds to a dramatic change in the Atlantic circulation intensity. According to Marisa Montoya, “If the glacial climate had been in the vicinity of that point, small wind changes could have caused sudden and significant climatic changes during that period”

The study was based on climatic simulations called Last Glacial Maximum (LGM) (the period of maximum extension of the perpetual ice sheets that took place over 21.000 years ago). These simulations have demonstrated the existence of a threshold after which a small change in wind speed causes disproportionately large changes in the sea current speed. The results indicate that these changes in wind speed could have had a particularly important role in the abrupt climatic change of the last ice age.

Researchers at Delft University of Technology (TU Delft) in The Netherlands have developed a technique for generating atom clusters made from silver and other metals. Surprisingly enough, these so-called super atoms (clusters of 13 silver atoms, for example) behave in the same way as individual atoms and have opened up a whole new branch of chemistry. A full account can be read in the new edition of TU Delft magazine Delft Outlook.

A small twisted wire, just like the filament in an incandescent bulb, but made of silver, forms the basis for the special silver particles.

If a silver thread is heated to around 900 degrees Celsius, it will generate vapour made up of silver atoms. The floating atoms stick to each other in groups. Small lumps of silver comprising for example 9, 13 and 55 atoms appear to be energetically stable and are therefore present in the silver mist more frequently that one might assume. Prof. Andreas Schmidt-Ott and Dr. Christian Peineke of TU Delft managed to collect these super atoms and make them suitable for more detailed chemical experiments.

Science

The underlying mechanism governing this stability in super atoms was described in Science by scientists from Virginia Commonwealth University in 2005. They had discovered metal super atoms, but from aluminium. Their aluminium clusters of 13, 23 and 37 atoms reacted in the same way as individual atoms because they comprised electrons that revolved around the atom cluster as a whole. These so-called outer layers were strikingly similar to the outer layers of elements from the periodic table.

The super atoms gave the periodic table a third dimension as it were, according to Schmidt-Ott: ‘The chemical properties of the super atoms that have been identified up until now are very similar to those of elements in the periodic table, because their outer layers are much the same. However, we may yet discover super atoms with a different outer layer, giving us another set of completely new properties.’