Researchers studied the impact of grass and grass/tree buffer strips on three herbicides commonly used in agriculture. The scientists studied the transport of the herbicides in both surface runoff and subsurface infiltration during two growing seasons.

Vegetative barriers reduce herbicide concentrations in runoff, but movement of herbicides through subsurface filtration actually increased. Total export of herbicides was reduced through the use of grass and grass/tree barriers. The research was conducted by Emmanuelle Caron, Pierre Lafrance, Jean-Christian Auclair of the University of Quebec, and Marc Duchemin of the Institute of Research and Development in Agri-Environment.

The results are reported in the March/April 2010 edition of the Journal of Environmental Quality, published by the American Society of Agronomy, the Crop Soil Science Society of America, and the Soil Science Society of America.

The results for the first year showed a 35% reduction in herbicide concentration in grass and grass/tree buffer strips than with no buffer. Herbicide concentrations in subsurface filtration increased 800-1200-% with buffer strips, although total overall concentration was reduced 40-60%. In 2005, total herbicide concentration exported through the buffer strips was 75-95% less than without the buffers. The findings indicate that grass barriers decrease surface water runoff while increasing subsurface infiltration, resulting in an overall loss of herbicides before reaching bodies of water.

Integrating trees into the barriers did not result in any significant differences. This was possible due to the fact that the trees were only two years old at the beginning of the study, and their root systems were not yet developed enough to demonstrate any impact. Further research is needed to determine the effects of long-established trees in buffer strips. Local meteorological conditions also play an important role in the efficiency of buffer strips, and the two years of the study experienced a wide range of variability that future long term research should address. PhysOrg

Now, scientists from several countries have confirmed that the volcanic processes at work beneath the Ethiopian rift are nearly identical to those at the bottom of the world’s oceans, and the rift is indeed likely the beginning of a new sea.

The new study, published in the latest issue of Geophysical Research Letters, suggests that the highly active volcanic boundaries along the edges of tectonic ocean plates may suddenly break apart in large sections, instead of little by little as has been predominantly believed. In addition, such sudden large-scale events on land pose a much more serious hazard to populations living near the rift than would several smaller events, says Cindy Ebinger, professor of earth and environmental sciences at the University of Rochester and co-author of the study.

“This work is a breakthrough in our understanding of continental rifting leading to the creation of new ocean basins,” says Ken Macdonald, professor emeritus in the Department of Earth Science at the University of California, Santa Barbara, and who is not affiliated with the research. “For the first time they demonstrate that activity on one rift segment can trigger a major episode of magma injection and associated deformation on a neighboring segment. Careful study of the 2005 mega-dike intrusion and its aftermath will continue to provide extraordinary opportunities for learning about continental rifts and mid-ocean ridges.”

“The whole point of this study is to learn whether what is happening in Ethiopia is like what is happening at the bottom of the ocean where it’s almost impossible for us to go,” says Ebinger. “We knew that if we could establish that, then Ethiopia would essentially be a unique and superb ocean-ridge laboratory for us. Because of the unprecedented cross-border collaboration behind this research, we now know that the answer is yes, it is analogous.”

Atalay Ayele, professor at the Addis Ababa University in Ethiopia, led the investigation, painstakingly gathering seismic data surrounding the 2005 event that led to the giant rift opening more than 20 feet in width in just days. Along with the seismic information from Ethiopia, Ayele combined data from neighboring Eritrea with the help of Ghebrebrhan Ogubazghi, professor at the Eritrea Institute of Technology, and from Yemen with the help of Jamal Sholan of the National Yemen Seismological Observatory Center. The map he drew of when and where earthquakes happened in the region fit tremendously well with the more detailed analyses Ebinger has conducted in more recent years.

Ayele’s reconstruction of events showed that the rift did not open in a series of small earthquakes over an extended period of time, but tore open along its entire 35-mile length in just days. A volcano called Dabbahu at the northern end of the rift erupted first, then magma pushed up through the middle of the rift area and began “unzipping” the rift in both directions, says Ebinger.

Since the 2005 event, Ebinger and her colleagues have installed seismometers and measured 12 similar—though dramatically less intense—events.

“We know that seafloor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this,” says Ebinger. She explains that since the areas where the seafloor is spreading are almost always situated under miles of ocean, it’s nearly impossible to monitor more than a small section of the ridge at once so there’s no way for geologists to know how much of the ridge may break open and spread at any one time. “Seafloor ridges are made up of sections, each of which can be hundreds of miles long. Because of this study, we now know that each one of those segments can tear open in a just a few days.”

Ebinger and her colleagues are continuing to monitor the area in Ethiopia to learn more about how the magma system beneath the rift evolves as the rift continues to grow.

Additional authors of the study include Derek Keir, Tim Wright, and Graham Stuart, professors of earth and environment at the University of Leeds, U.K.; Roger Buck, professor at the Earth Institute at Columbia University, N.Y.; and Eric Jacques, professor at the Institute de Physique du Globe de Paris, France. redOrbit

“Whale poop!” shouted several researchers in unison, as biologists scrambled to collect the floating reddish specimens Saturday as part of a comprehensive study of the ocean’s ecology off the Northern California coast.

The color of the whale excrement meant that the huge creature had been feeding mostly on a tiny shrimp-like crustacean called krill instead of fish and anchovies, its preferred food in recent decades. It is a change in diet that several bird species at the Farallon National Wildlife Refuge are unable to make, according to researchers in a joint ocean survey by the Cordell Bank National Marine Sanctuary, the Gulf of the Farallones National Marine Sanctuary and PRBO Conservation Science.

As a result, colonies of fish-eating cormorants, seagulls and murres failed to breed this year on the Farallon Islands. Over the past few months, dozens of dead birds and even sea lions have been found on local beaches.

Anchovies have disappeared, and scientists don’t know why. The researchers on the vessel believe that, in their absence, birds and mammals like humpback whales that eat krill are thriving while the ones that are eating only fish are in trouble, and the whale excrement served as evidence.

“We’ve had an extraordinary number of dead animals,” said Jan Roletto, the research coordinator for the Gulf of the Farallones National Marine Sanctuary. “It seems to be that the animals that suffered the most were the animals that forage on anchovies.”

Brandt’s cormorants, a black bird with white plumes that can dive as deep as 300 feet for its prey, did not produce any chicks this year on the Farallones or on Alcatraz. That’s compared with 15,000 chicks in 2007.

Breeding fails

For the anchovy-loving bird, it was the first complete breeding failure in 40 years during a year without El Niño conditions so far, according to scientists at PRBO, formerly known as the Point Reyes Bird Observatory.

Western gulls and common murres produced about one-seventh of the number of chicks they normally hatch. Researchers on the Farallones reported an increase in predation on the chicks that were produced, mainly because the parents were too far away looking for food.

Beachgoers probably noticed the death toll. Six to eight times the normal number of dead cormorants and sea lions were found on Bay Area beaches in May, June and July, according to researchers. The death toll in each case involves birds and marine mammals that prey on anchovies and other fish.

The deaths and breeding failures are all the more troubling because there appears to be plenty of krill, rockfish and other prey species to feed the seagoing birds and mammals.

Jaime Jahncke, the director of marine ecology for PRBO, said common murres had previous breeding failures in 1982-83 and in 1991-92, but both times the problems were linked to El Niño, a weather condition associated with warmer ocean temperatures and atmospheric conditions that cause heavy storms. Although forecasters say an El Niño is forming in the tropics, it has not yet hit California, Jahncke said.

No explanation

“I don’t know what it means, but it’s not good,” Jahncke said. “There are a lot of changes happening, and none of them have a clear explanation.”

Seagoing birds and mammals near the Farallon Islands depend on krill, anchovies and other prey that are attracted to conditions produced when cold, deep ocean currents bounce off the underwater outcropping called the Cordell Bank, forcing nutrients upward. The nutrients are most abundant during the transition from winter to spring.

Spring arrives an average of 20 days earlier than it did in 1970, Jahncke said. There has also been an increase in the strength of the upwellings over the past two decades, he said.

Apart from the lack of anchovies, that is probably a good thing.

The team of scientists on the boat spotted several blue whales before the humpback put on its show.

The abundance of blue whales, which feed almost exclusively on krill, and the evidence provided by the humpback made it clear that there is plenty of krill in the ocean.

“Whales primarily over the last decade have been feeding on fish,” said Lisa Etherington, the research coordinator for the Cordell Bank National Marine Sanctuary. “The last couple of years they’ve been feeding on krill. We don’t know why.”

Wild fluctuations

Jahncke said salmon smolt also feed on krill, a fact that may or may not help the beleaguered Central Coast chinook. The Cassin’s auklet, a small, chunky seabird that feeds on krill, had above-average nesting success this year.

But wild fluctuations are now almost normal, according to the researchers, who are concerned that the El Niño predicted for next year will cause a further decline in the numbers of birds. By Peter Fimrite, San Francisco Chronicle.