Global Warming Could Lead to Saltier Beaches
A new study revealed that global warming are causing the fluctuation of salinity in coastal zones, resulting to saltier beaches.
The study, published in the journal Scientific Reports, showed that the increases in temperature associated with global warming will not only make the intertidal zones of beaches saltier, but also affect the salinity pattern of pore water, affecting animals and plants living in intertidal zones.
"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," explained Xiaolong Geng, a postdoctoral fellow at NJIT and the principal author of the study, in a statement.
The researchers noted that the rates of evaporation and salinity are mainly determined by temperature and relative humidity, while tide and wave flows dilute the salt content of coastal zones. This suggests that the combined effects of temperature, tides and waves are also responsible for subsurface salinity distribution in beaches, as opposed to previous studies considering seawater infiltration as the main cause of increases in pore water salinity.
For the study, the researchers analyzed 400 sediments from a beach in Delaware Bay collected during the sequential phases of a complete tidal cycle, from day to night, on seven discontinuous days.
Surprisingly, the researchers discovered that sediments in some section of the beach have salt concentration four times as high as the ocean that washes over them. The salt concentrations of near shore seawater measured 25 grams per liter, while salt concentration in the upper intertidal zone of high tide line measured 60 to 100 grams per liter.
Changes in the salinity of pore-water can greatly animals living in the intertidal zone. Animals such as crabs and mussels burrow themselves in the beach to find food and hide from predators. If the salt concentrations are too high or too low, these animals will move away, reducing the available food for predators, such as birds and sea mammals, feeding on them.