On an arid plateau in the Andes Mountains of southern Bolivia, a Case Western Reserve University researcher flagged what turned out to be the fossil remains of a tortoise nearly five feet long - a find indicating this highland was likely less than a kilometer above sea level 13 million years ago.

Fossilized shell pieces of a much smaller, aquatic turtle found nearby support the altitude estimate and also indicate the climate was much wetter than today.

The remains are the first records of fossil turtles from the Miocene epoch in Bolivia, and their presence challenges a recent isotope-based study that estimated the massive plateau, called the Altiplano, near what is now the town of Quebrada Honda, was 2 to 3.2 kilometers high at that time.

In addition, the fossils provide a glimpse into climate change caused by rising mountains, which may help scientists understand climate change underway now.

"We're trying to understand how tectonic plate activity and changing climate affected species diversity in the past," said Darin Croft, an anatomy professor at Case Western Reserve University School of Medicine and a paleomammalogist. "One way all this diversity we see in the South American tropics today was generated was through elevation. Mountains create many different climates and ecosystems in a small area, which promotes speciation."

Croft found the tortoise remains in an embankment after he missed a turn on a path near Quebrada Honda and was working his way back toward his regular research site. Croft and Federico Anaya, a member of the geological engineering faculty at Universidad Autonoma Tomas Frias in Posoti, later identified other, more fragmentary tortoise remains from other sites in the area.

After returning to the United States, Croft sent photographs and three-dimensional computer-generated images of the remains to Edwin Cadena, a turtle expert now at Yachay Tech University in Ecuador.

Cadena identified the tortoise as a member of the same genus as the Galapagos tortoise, Chelonoidis. He identified the extinct freshwater turtle as belonging to the genus Acanthochelys, whose surviving members occur throughout much of tropical South America.

The animals are ectotherms, commonly called cold-blooded. Their reliance on the outside air to control their body temperature can be used as a proxy for the temperature where they lived and, therefore, elevation.

The ancient tortoise and aquatic turtle most likely would have had physiological requirements much like their modern relatives, which generally live at altitudes of up to about 500 meters and can't thrive or reproduce at much higher elevations because of the cooler temperatures, Croft said.

Miocene fossilized leaf remains are scant in Bolivia, but those that have been found tend to support the findings of warmer temperatures, lower altitude, and greater precipitation than today.

The Andes were formed by subduction - a process in which one tectonic plate is shoved under another. How quickly the mountains rose to their current elevation is not fully answered.

As the highest geological feature in South America, the mountain chain affects global air circulation patterns and plays a major role in global climate.

"With current global climate change, we'd like to have a better idea of what to expect under different scenarios - how 1-degree warming or 2-degree warming will affect sea levels and animals," Croft continued. "If we want to model the future, we need to understand and model the past."

Looking back, if the Andes Mountains were less than 1 kilometer high during the late Miocene, they would have had a much smaller effect on global circulation than if they were two or three times as high, close to their modern elevation near Quebrada Honda.

The researchers believe they have more evidence from extinct animals that this part of the Altiplano was less than a kilometer above sea level 13 million years ago. They found fossil remains of a large snake in the same rock layer as the turtles. Those bones are currently under study by Croft and colleagues.

The research is published in the Journal of South American Earth Sciences.

--SPACE STORY- ocean-tech slug1 225 22-DEC-49 PRO as a sustainable energy production system is crippled by biofouling PRO as a sustainable energy production system is crippled by biofouling pressure-retarded-osmosis-pro-renewable-energy-lg.jpg pressure-retarded-osmosis-pro-renewable-energy-bg.jpg pressure-retarded-osmosis-pro-renewable-energy-sm.jpg "The study showed that organic matter and bacteria in the feed wastewater stream resulted in extreme biofouling development across the feed spacer as well as the membrane support layer, thereby crippling PRO performance," explains Bar-Zeev. "These results will likely extend to other natural waters, such as river waters, where dissolved organic matter and bacteria are also prevalent." American Associates, Ben-Gurion University of the Negev
by Staff Writers Sede Boqer, Israel (SPX) Dec 30, 2015 Researchers at the Zuckerberg Institute for Water Research at Ben-Gurion University of the Negev (BGU) and Yale University have determined that pressure-retarded osmosis technology is not feasible primarily due to biofouling (the accumulation of organic material as well as different organisms such as algae and bacteria on various surfaces that impairing structures and hinder system performance).

Pressure-retarded osmosis (PRO) is a process that for several decades has been considered to have potential as a sustainable energy source. It utilizes various salinity gradients, such as sea and river water, or desalination brine and wastewater.

In PRO, water from a low-salinity feed solution permeates through a membrane into a pressurized, high-salinity draw solution. Power is obtained by depressurizing the draw through a hydro-turbine.

According to the new study published in the journal Environmental Science and Technology (ACS Publications), researchers at the Zuckerberg Institute and Yale University found that, "power generation by PRO produces little and next to nothing due to biofouling caused by bacteria that clog the membrane structure and the feed channel." Prior to this study, researchers from Yale reported that this technology is thermodynamically challenging and is hardly viable.

"While the concept of using an 'osmotic gradient' to harness power has existed since the 1970s, our research shows that commercial PRO is currently 'dead in the water'," says Zuckerberg's Dr.

Edo Bar-Zeev. "Biofouling is detrimental to the process and can't be mitigated since there are no membranes today that are specifically designed for PRO."

He claims that to make PRO viable, the process requires either sterile streams on both sides or a new membrane design. "These membranes must be dedicated for PRO technology instead of using the current forward osmosis (FO) membranes," Dr. Bar-Zeev explains.

In the study, researchers explored the PRO's efficiency and practicality under biofouling conditions using synthetic wastewater secondary effluents and seawater reverse osmosis (SWRO) desalination brine. Experiments were conducted in a small-scale PRO setup using thin-film composite FO membrane and fabric feed spacers.

"The study showed that organic matter and bacteria in the feed wastewater stream resulted in extreme biofouling development across the feed spacer as well as the membrane support layer, thereby crippling PRO performance," explains Bar-Zeev. "These results will likely extend to other natural waters, such as river waters, where dissolved organic matter and bacteria are also prevalent."

Other researchers that were closely involved in the study include Prof. Menachem Elimelech, Yale University, who is also on the Scientific Advisory Board of the Zuckerberg Institute for Water Research; Anthony P. Straub, Department of Chemical and Environmental Engineering, Yale University; and Dr. Francois Perreault, School of Sustainable Engineering and the Built Environment, Arizona State University.