Nav: Home

Global warming's next surprise: Saltier beaches

August 11, 2016

Batches of sand from a beach on the Delaware Bay are yielding insights into the powerful impact of temperature rise and evaporation along the shore that are in turn challenging long-held assumptions about what causes beach salinity to fluctuate in coastal zones that support a rich network of sea creatures and plants.

The findings have implications for the migration and survival of invertebrates such as mussels and crabs as global warming drives temperatures higher.

A first major study of the effects of evaporation on the flow of subsurface water and salinity, or salt content, in the beach intertidal zone - the section of the beach between the low and high tide marks - is being published today in Scientific Reports, an online affiliate of Nature.

The study, by New Jersey Institute of Technology's Center for Natural Resources Development (CNRDP) and led by two environmental engineers and a coastal geologist, shows that sediments from some sections of Slaughter Beach in Delaware have salt concentrations four times as high as the ocean water that washes over them. The finding came as a surprise.

The nearshore seawater the team measured had salt concentrations of 25 grams per liter (g/L), leading the researchers to expect that the subsurface water in areas of the beach it infiltrated would have similar or even lower levels as seawater mixes with inland groundwater in this zone. However, they discovered that the average salinity in the upper intertidal zone - the high tide line - was 60 g/L, with some values reaching as high as 100.

"These elevated levels can only be caused by evaporation, as there is no other mechanism for increasing the salt in pore water - the water trapped between the grains of sediment," said Xiaolong Geng, a postdoctoral fellow at NJIT and the principal author of the study, noting that the rates of evaporation - and salinity - are thus mainly determined by temperature and relative humidity, while tide and wave flows dilute a beach's salt content.

"Previous studies have identified seawater as the primary source of salinity in coastal aquifer systems, thereby concluding that seawater infiltration always increases pore-water salinity by seawater-groundwater mixing dynamics," said Michel Boufadel, director of the CNRDP, who is also an author of the study. "Based on what we learned, we think this finding should alter the way water management in coastal areas is conducted."

The team analyzed nearly 400 sediment samples collected during the sequential phases of a complete tidal cycle, from day to night, on seven discontinuous days.

The intertidal, or littoral, zone, is a dynamic habitat, washed by seawater at high tide and uncovered at low tide, that is favored by crabs, mussels and sea anemones, the birds and sea mammals that feed on them, and plants such as kelp. Many of these animals burrow in the beach to find food and to seek protection from predators and the action of waves, and are in near constant contact with pore water.

The researchers have developed models that show that increases in temperature associated with global warming will not only make inland locations more salty, but would also create drastically different pattern of pore water salinity that will have implications for animals and plants in the intertidal zone.

"Evaporation is an important driver of underground water flow and salinity gradients, and animals such as mussels and crabs are affected by changes in salinity. If the concentrations are too high or too low, they will move away," noted Geng.

Nancy Jackson, a professor of coastal geomorphology in the Department of Chemistry and Environmental Science and the study's third author, collected the beach samples from Slaughter Beach and provided interpretations of pore water dynamics.
-end-
About NJIT

One of the nation's leading public technological universities, New Jersey Institute of Technology (NJIT) is a top-tier research university that prepares students to become leaders in the technology-dependent economy of the 21st century. NJIT's multidisciplinary curriculum and computing-intensive approach to education provide technological proficiency, business acumen and leadership skills. With an enrollment of 11,300 graduate and undergraduate students, NJIT offers small-campus intimacy with the resources of a major public research university. NJIT is a global leader in such fields as solar research, nanotechnology, resilient design, tissue engineering and cybersecurity, in addition to others. NJIT ranks fifth among U.S. polytechnic universities in research expenditures, topping $110 million, and is among the top 1 percent of public colleges and universities in return on educational investment, according to Payscale.com. NJIT has a $1.74 billion annual economic impact on the state of New Jersey.

New Jersey Institute of Technology

Related Global Warming Articles:

Intensified global monsoon extreme rainfall signals global warming -- A study
A new study reveals significant associations between global warming and the observed intensification of extreme rainfall over the global monsoon region and its several subregions, including the southern part of South Africa, India, North America and the eastern part of the South America.
Global warming's impact on undernourishment
Global warming may increase undernutrition through the effects of heat exposure on people, according to a new study published this week in PLOS Medicine by Yuming Guo of Monash University, Australia, and colleagues.
Global warming will accelerate water cycle over global land monsoon regions
A new study provides a broader understanding on the redistribution of freshwater resources across the globe induced by future changes in the monsoon system.
Comparison of global climatologies confirms warming of the global ocean
A report describes the main features of the recently published World Ocean Experiment-Argo Global Hydrographic Climatology.
Six feet under, a new approach to global warming
A Washington State University researcher has found that one-fourth of the carbon held by soil is bound to minerals as far as six feet below the surface.
Can we limit global warming to 1.5 °C?
Efforts to combat climate change tend to focus on supply-side changes, such as shifting to renewable or cleaner energy.
Global warming: Worrying lessons from the past
56 million years ago, the Earth experienced an exceptional episode of global warming.
Global warming: More insects, eating more crops
Rising global temperatures are expected to significantly increase crop losses from insects, especially in temperate regions, a new study finds.
Global fisheries could still become more profitable despite global warming
Global commercial fish stocks could provide more food and profits in the future, despite warming seas, if adaptive management practices are implemented.
Global warming may be twice what climate models predict
Future global warming may eventually be twice as warm as projected by climate models under business-as-usual scenarios and even if the world meets the 2°C target sea levels may rise six metres or more, according to an international team of researchers from 17 countries.
More Global Warming News and Global Warming Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Accessing Better Health
Essential health care is a right, not a privilege ... or is it? This hour, TED speakers explore how we can give everyone access to a healthier way of life, despite who you are or where you live. Guests include physician Raj Panjabi, former NYC health commissioner Mary Bassett, researcher Michael Hendryx, and neuroscientist Rachel Wurzman.
Now Playing: Science for the People

#544 Prosperity Without Growth
The societies we live in are organised around growth, objects, and driving forward a constantly expanding economy as benchmarks of success and prosperity. But this growing consumption at all costs is at odds with our understanding of what our planet can support. How do we lower the environmental impact of economic activity? How do we redefine success and prosperity separate from GDP, which politicians and governments have focused on for decades? We speak with ecological economist Tim Jackson, Professor of Sustainable Development at the University of Surrey, Director of the Centre for the Understanding of Sustainable Propserity, and author of...
Now Playing: Radiolab

An Announcement from Radiolab