By 2100, rising sea levels could push coastal groundwater to rise in many coastal urban environments and resultant inundation of contaminated soils by rising groundwater can alter physical, biological and geochemical conditions for coastal communities according to new research.
The new research conducted by a team led by University of California Berkeley associate professor Kristina Hill has mapped the growing threat from under the surface water as climate change raises sea water levels which in turn raises coastal groundwater levels.
The team found that altered products in the impacted soils can be more toxic and (or) more mobile under future conditions driven by sea-level rise and ground-water rise. As groundwater nears the surface, it can damage human infrastructure and it can also spread hazardous substances in the soil, exposing people and ecosystems nearby.
The new study found that 326 sites in the areas included in the study may be vulnerable to changes in groundwater depth or flow direction as a result of rising sea levels. The researchers said the toxic sites include everything from former military bases and chemical factories to gas stations and dry cleaners.
Leaks and spills from these industries can contaminate the soil with a variety of hazards, including heavy metals, volatile organic chemicals, pesticides and herbicides and radioisotopes.
Excavating a site to remove toxins can be very costly. Instead, contaminated sites are often remediated by adding a cap of low-permeability material that protects the tainted soil from rainwater and, ideally, keeps the hazardous material dry and immobilised.
The US Geological Survey coastal geologist Patrick Bernard said the sheer number of sites where there are these dangerous contaminants that could be liberated due to the rising water levels is huge.
He said many of the polluted areas have been managed without regard for groundwater rise.
The researchers said the link between climate change, the sea and underground water may not be obvious but it is intimate. M