Wednesday, July 10, 2019

The World Needs a Global Agenda for Sand

Date: July 2, 2019
Source: University of Colorado at Boulder
Summary: Sand is a key ingredient in the recipe of modern life, and yet it is being extracted faster than it can be replaced.

What links the building you live in, the glass you drink from and the computer you work on? The answer is smaller than you think and is something we are rapidly running out of: sand.

In a commentary published today in the journal Nature, a group of scientists from the University of Colorado Boulder, the University of Illinois, the University of Hull and Arizona State University highlight the urgent need for a global agenda for sand.

Sand is a key ingredient in the recipe of modern life, and yet it might be our most overlooked natural resource, the authors argue. Sand and gravel are being extracted faster than they can be replaced. Rapid urbanization and global population growth have fueled the demand for sand and gravel, with between 32 and 50 billion tons extracted globally each year.

"From 2000-2100 it is projected there will be a 300 percent increase in sand demand and 400 percent increase in prices," said Mette Bendixen, a researcher at CU Boulder's Institute of Arctic and Alpine Research (INSTAAR). "We urgently require a monitoring program to address the current data and knowledge gap, and thus fully assess the magnitude of sand scarcity. It is up to the scientific community, governments and policy makers to take the steps needed to make this happen."

A lack of oversight and monitoring is leading to unsustainable exploitation, planning and trade. Removal of sand from rivers and beaches has far-reaching impacts on ecology, infrastructure, national economies and the livelihoods of the 3 billion people who live along the world's river corridors. Illegal sand mining has been documented in 70 countries across the globe, and battles over sand have reportedly killed hundreds in recent years, including local citizens, police officers and government officials.

"Politically and socially, we must ask: If we can send probes to the depths of the oceans or the furthest regions of the solar system, is it too much to expect that we possess a reliable understanding of sand mining in the world's great rivers, and on which so much of the world's human population, rely?" said Jim Best, a professor at the University of Illinois Department of Geology. "Now is the time to commit to gaining such knowledge by fully grasping and utilizing the new techniques that are at our disposal."

In order to move towards globally sustainable sand extraction, the authors argue that we must fully understand the occurrence of sustainable sources and reduce current extraction rates and sand needs, by recycling concrete and developing alternative to sand (such as crushed rocks or plastic waste materials). This will rely on a knowledge of the location and extent of sand mining, as well as the natural variations in sand flux in the world's rivers.

"The fact that sand is such a fundamental component of modern society, and yet we have no clear idea of how much sand we remove from our rivers every year, or even how much sand is naturally available, makes ensuring this industry is sustainable very, very difficult" said Chris Hackney, research fellow at the University of Hull's Energy and Environment Institute. "It's time that sand was given the same focus on the world stage as other global commodities such as oil, gas and precious metals."

"The issue of sand scarcity cannot be studied in geographical isolation as it has worldwide implications," said Lars L. Iversen, a research fellow at Arizona State University's Julie Ann Wrigley Global Institute of Sustainability. "The reality and size of the problem must be acknowledged -- and action must be taken -- on a global stage. In a rapidly changing world, we cannot afford blind spots."

The Carlsberg Foundation and the Danish National Research Foundation provided funding for the study.

Story Source: University of Colorado at Boulder. "The world needs a global agenda for sand." ScienceDaily. ScienceDaily, 2 July 2019.

Wednesday, June 19, 2019

Alarming Study Finds Plastic Ocean Pollution Harms Bacteria That Produce The Oxygen We Breathe

Rich Haridy | May 15th, 2019

Chemicals that leach out of plastic rubbish were found to impair the growth of bacteria in the ocean responsible for producing a large volume of the oxygen in our atmosphere (Credit: ead72/Depositphotos)

An important new study is raising novel concerns over the effects of plastic pollution in our oceans. For the first time researchers investigated how a common ocean bacteria, responsible for producing over 10 percent of oxygen in the atmosphere, is negatively impaired by chemicals that can leach out of plastic products.

Prochlorococcus is a tiny cyanobacterial genus that was only discovered a little over 30 years ago. This remarkable cyanobacterium is not only the smallest photosynthesizing organism on the planet, but also one of the most abundant. Some estimates suggest there are as much as three octillion Prochlorococcus in the ocean, where they not only help keep the waters healthy, but also produce a substantial volume of the oxygen we breathe.

"These tiny microorganisms are critical to the marine food web, contribute to carbon cycling and are thought to be responsible for up to 10 per cent of the total global oxygen production," says Lisa Moore, from Australia's Macquarie University and co-author on the new study. "So one in every 10 breaths of oxygen you breathe in is thanks to these little guys, yet almost nothing is known about how marine bacteria, such as Prochlorococcus respond to human pollutants."

To fill this substantial gap in scientific knowledge, the researchers took two different strains of the cyanobacteria and in laboratory conditions exposed them to chemicals known to leach out of common plastic products. The results were striking with the chemicals impairing the Prochlorococcus' growth, reducing its ability to photosynthesize, and altering the expression of a large number of its genes.

The study obviously has a number of limitations if one is trying to extrapolate these results to the general effect of plastics in the ocean. The researchers do note that their experiments do not equate to specific concentrations of plastics in the ocean, but instead they're designed to try to better understand what the impact of plastic pollution could be on this vitally important population of microorganisms in our marine systems.

"Our data shows that plastic pollution may have widespread ecosystem impacts beyond the known effects on macro-organisms, such as seabirds and turtles," says lead author on the study, Sasha Tetu. "If we truly want to understand the full impact of plastic pollution in the marine environment and find ways to mitigate it, we need to consider its impact on key microbial groups, including photosynthetic microbes."

While a great deal of activity currently circles the problem of plastics, and microplastics, in our ocean ecosystems, very little is known about what actual damage these pollutants are causing. Further study will be necessary to investigate the effects of these plastics on microorganisms in the actual ocean, but the researchers hypothesize this to potentially be a significant global issue.

The new study notes the nearly two trillion plastic pieces that make up the infamous Great Pacific Garbage Patch cross over an area where the Prochlorococcus cyanobacterium is most abundant. Alongside this, a recent study did reveal that floating plastic rubbish can leach chemicals into ambient seawater in volumes high enough to alter the activity of local microbial populations. So, although this new research was completed in laboratory environments in generally hypothetical scenarios, the problem of plastic chemicals leaching into the ocean is one that certainly needs attention.

The new study was published in the journal Communications Biology.

Source: Macquarie University

Story Source:

Wednesday, May 8, 2019

Radical Desalination Approach May Disrupt the Water Industry

Date: May 6, 2019
Source: Columbia University School of Engineering and Applied Science
Summary: Researchers report that they have developed a radically different desalination approach--''temperature swing solvent extraction (TSSE)''--for hypersaline brines. Their study demonstrates that TSSE can desalinate very high-salinity brines, up to seven times the concentration of seawater.

This is an illustration describing fresh water production from hypersaline brines by temperature swing solvent extraction.
Credit: Chanhee Boo/Columbia Engineering

Hypersaline brines -- water that contains high concentrations of dissolved salts and whose saline levels are higher than ocean water -- are a growing environmental concern around the world. Very challenging and costly to treat, they result from water produced during oil and gas production, inland desalination concentrate, landfill leachate (a major problem for municipal solid waste landfills), flue gas desulfurization wastewater from fossil-fuel power plants, and effluent from industrial processes.

If hypersaline brines are improperly managed, they can pollute both surface and groundwater resources. But if there were a simple, inexpensive way to desalinate the brines, vast quantities of water would be available for all kinds of uses, from agriculture to industrial applications, and possibly even for human consumption.

A Columbia Engineering team led by Ngai Yin Yip, assistant professor of earth and environmental engineering, reports that they have developed a radically different desalination approach -- "temperature swing solvent extraction (TSSE)" -- for hypersaline brines. The study, published online in Environmental Science & Technology Letters, demonstrates that TSSE can desalinate very high-salinity brines, up to seven times the concentration of seawater. This is a good deal more than reverse osmosis, the gold-standard for seawater desalination, and can hold handle approximately twice seawater salt concentrations.


Currently, hypersaline brines are desalinated either by membrane (reverse osmosis) or water evaporation (distillation). Each approach has limitations. Reverse osmosis methods are ineffective for high-saline brines because the pressures applied in reverse osmosis scale with the amount of salt: hypersaline brines require prohibitively high pressurizations. Distillation techniques, which evaporate the brine, are very energy-intensive.

Yip has been working on solvent extraction, a separation method widely employed for chemical engineering processes. The relatively inexpensive, simple, and effective separation technique is used in a wide range of industries, including production of fine organic compounds, purification of natural products, and extraction of valuable metal complexes.

"I thought solvent extraction could be a good alternative desalination approach that is radically different from conventional methods because it is membrane-less and not based on evaporative phase-change," Yip says. "Our results show that TSSE could be a disruptive technology -- it's effective, efficient, scalable, and can be sustainably powered."

TSSE utilizes a low-polarity solvent with temperature-dependent water solubility for the selective extraction of water over salt from saline feeds. Because it is membrane-less and not based on evaporation of water, it can sidestep the technical constraints that limit the more traditional methods. Importantly, TSSE is powered by low-grade heat (< 70 C) that is inexpensive and sometimes even free. In the study, TSSE removed up to 98.4% of the salt, which is comparable to reverse osmosis, the gold standard for seawater desalination. The findings also demonstrated high water recovery >50% for the hypersaline brines, also comparable to current seawater desalination operations. But, unlike TSSE, reverse osmosis cannot handle hypersaline brines.

"We think TSSE will be transformational for the water industry," he adds. "It can displace the prevailing practice of costly distillation for desalination of high-salinity brines and tackle higher salinities that RO cannot handle," Yip adds. "This will radically improve the sustainability in the treatment of produced water, inland desalination concentrate, landfill leachate, and other hypersaline streams of emerging importance. We can eliminate the pollution problems from these brines and create cleaner, more useable water for our planet."

Yip's TSSE approach has a clear path to commercialization. The heat input can be sustainably supplied by low-grade thermal sources such as industrial waste heat, shallow-well geothermal, and low-concentration solar collectors. He is now working on further refining how TSSE works as a desalination method so that he can engineer further improvements in performance and test it with real-world samples in the field.

Story Source:
Columbia University School of Engineering and Applied Science. "Radical desalination approach may disrupt the water industry." ScienceDaily. ScienceDaily, 6 May 2019.