Of the many crises facing the world today, few expected a global shortage of sand to be among them. Whether in the concrete around us or the phones in our hands, modern society probably uses more sand than any other natural resource. Getting hold of the right stuff, however, has suddenly become a major concern for governments, industry and coastal communities alike.
“Sand is a resource that is not as renewable as people originally thought it was,” said Zach Sickmann, a postdoc at the University of Texas Institute for Geophysics, who recently published research revealing how thousands of years of human activity has fundamentally changed the distribution of sand around the world.
“One of the things that is going to be very important in the future is determining responsible ways to extract sand from the system and reliable ways to trace commodity sand back to its source.”
Today, by far the largest demand for sand is for concrete used in construction, driven in large part by a new boom in urbanization across Asia. As many countries are beginning to realize, however, high quality sand suitable for construction is in short supply.
“When you look at the economics of the global sand trade you see that many countries like Japan and Singapore just don’t have enough sand to meet demand,” said Sickmann. Indeed, a worrying illegal sand trade has already emerged in South Asia, where countries like Cambodia, Indonesia and Vietnam have been forced to restrict sand exports to tackle corruption and mitigate the enormous environmental damage of digging up so much sand. A lack of research about the issues means that the impact of sand mining might be even worse than many fear.
“There’s a whole cascade of environmental effects that aren’t really understood,” said Sickmann. “Going forward it will be important to develop new methods to understand the effects of sand extraction on natural sedimentary systems and to try to ‘fingerprint’ sand mined illicitly or irresponsibly.”
Sickmann is a sedimentologist who has spent much of his career studying Monterey Bay, in central California. Now at UTIG, Sickmann joins one of several initiatives led by scientists at UTIG and UT Jackson School of Geosciences that answer big questions with societal importance about how sand and sediments are deposited. These range from projects to chart the depositional history of the Gulf of Mexico, to a Rapid Response team equipped to map how powerful storms can reshape the seafloor.
Ongoing research also includes a project funded by the Bureau of Ocean Energy Management to identify future sand resources in the Gulf. Sickmann’s Monterey Bay work is an important addition because it gives a different angle to the relationship between humans and sand.
His paper, which was published in the journal Quarternary Science Reviews, in October titled “Using provenance analysis in an Anthropocene natural laboratory” revealed how human activity over thousands of years has changed the global dispersal of sand, including how much sand is transported, what it’s made of and where it goes.
The story begins about 10,000 years ago with the emergence of organized agriculture. By cutting down trees, growing crops and grazing livestock, the Neolithic people of the time were inadvertently making their landscape much more vulnerable to erosion. The subsequent increase in the amount of sediment, said Sickmann, can be seen in the sedimentary record, beginning in Neolithic times all the way to the modern era.
However, things make an unexpected reversal during the late industrial revolution.
“Starting around 1900 and really ramping up after the second world war, that rate of sediment flux shifts pretty profoundly,” said Sickmann. As countries began industrializing, hydroelectric dams appeared and rivers were redirected to regulate water for agriculture. Civil engineers had suddenly begun to dictate where sediment can and can’t go. Moreover, the sudden boom in demand for concrete drove widespread sand minding which began removing sand directly from the system.
These changes to the amount of sediment reaching coastlines can have dramatic impacts on coastal environments.
“In many cases, when you decrease the amount of sediment reaching coastal environments, coast lines and beaches begin to quickly recede,” said Sickmann.
“Along coastlines that naturally lose sand to offshore, deep ocean environments or on coastlines that are naturally subsiding, as soon as you start shutting that sedimentation off, you start losing beaches,” Sickmann added.
Previous research had predicted that changes in the rate of sediment flux could affect coastlines in this way. What Sickmann’s work does is provide a way to quantify how human activity affects specific natural sources of sediment by compositionally “fingerprinting” sand across a natural sediment dispersal system. This technique, called sedimentary provenance analysis, is commonplace in sedimentary geology, but rarely used to target human alterations to natural sediment supply. By sampling and describing the composition of sand from onshore sediment sources, down rivers that transport sediment and into the beaches and deep ocean areas that receive that sediment, human activity like sand-mining can be teased out from unexpected shifts in composition.
“Humans have been altering and exploiting natural sediment dispersal systems for thousands of years,” said Sickmann “we are only recently becoming aware of the fact that these alterations need to be better understood and quantified.” The problem, added Sickmann, is that our current understanding of sedimentology does not properly examine questions of the human effect on how sediment is dispersed.
“Anthropogenic perturbations are actually something that a sedimentary geologist can target specifically, with skill sets that they already have, to address questions that not only have implications for the interpretation of all sedimentary systems in nature, but also specifically can address questions with respect to societally impactful issues like coastal and environmental change,” he said.
Sickmann believes established sedimentology techniques like provenance analysis can be applied to “fingerprint” sand and trace its origin beyond natural sediment dispersal patterns.
“Sand mined from a specific river or beach could carry a unique compositional signature through the sand refining process in the same way that it would through natural sediment dispersal,” said Sickmann. “If specific compositional ‘fingerprints’ could be defined for environmentally sensitive sand sources, it may be possible to tie commodity sand back to its natural source.”
Sickmann hopes to continue to develop this method as part of a multidisciplinary approach with collaborators like Dr. Aurora Torres (Michigan State/Université catholique de Louvain) to better understand and address the global sand crisis.
Regardless of potential future applications in helping authorities track the origin of illegal sand, it is already clear that such techniques are useful in understanding human-sediment interactions in natural systems past, present and future.