Worldwide Salinity Increase
Over the years, many scientists researched the change in salinity of rivers and freshwater sources. They all reached a similar conclusion: overall salinity in fresh bodies of water is rising. In 2005, a group of scientists published a paper studying the rise of salinity in the Northeast part of the United States. To learn more, you can read their paper here. The general conclusion was that salinity levels in fresh bodies of water were rising due to salting the roads in the winter.
This explains the rising salinity in the north, but it doesn’t justify the overall trend of rising salinity. Florida roads rarely ice up, if at all, yet salinity is still rising. There are many factors that increase salinity, but they all can be found under the category of pollution. Acid rain and fertilizer runoff are two of the largest contributors.
What is Acid Rain and Fertilizer Runoff?
Acid rain happens when sulfur dioxide and nitrogen oxides enter the air (typically from burning fossil fuels). As the molecules travel through the air, they mix and react with water vapor, oxygen, and other chemicals to form acid rain. When acid rain falls and hits pavement or rocks (especially Florida limestone), a small part of the rock dissolves and releases an alkaline salt called calcium carbonate. When the water runs down into a city drain or a nearby waterway, it carries this salt with it. Overtime, this small amount of additional salt accumulates and significantly raises salinity levels. There is a simple chart above demonstrating this pathway.
The more concrete cities we build, the more likely acid rain dissolves rock and carries salt into local waters. Sujay Kaushal, a geology professor at the University of Maryland, and his team of scientists found that “a 1 percent increase in paved surfaces could boost salt concentrations in nearby water bodies to levels more than 10 times higher than pristine forested conditions.” This is the same group of scientists that wrote about the overall increase of salinity in the Northeast United States.
Most of us have seen the recent expansion of highway US 19, so it is not surprising that Crystal River has become saltier. On top of expanding pavement, the city of Crystal River continues to develop and increase housing. More houses not only means more concrete, but also more yards. More yards means more fertilizer, and more fertilizer means more fertilizer runoff – the second major factor in rising salinity. Many types of fertilizer contain harmful salts like potassium chloride or ammonium sulfate. Overuse of fertilizer combined with rain causes these salts to enter nearby waterways and make the water saltier.
So, Salinity is Rising, but What’s the Harm?
Even fluctuations of .05% salt concentration is enough to kill marine life. The article linked here goes into detail about what exactly prevents freshwater life from living in saltwater.
Increased salinity not only harms marine life, but it also can be detrimental to humans. When salty water travels through pipes to our faucet, it corrodes harmful metal from inside the pipes. This metal enters our drinking water and gets consumed, causing many medical problems. This is what happened, with disastrous consequences, to Flint, Michigan’s water (https://www.youtube.com/watch?v=nTpsMyNezPQ).
It is very difficult to reverse the effects of increased salinity, and it is critical we are cognizant of what dangers lie ahead without action and awareness. One of the main solutions to help counter rising salinity is through planting native vegetation. This is exactly what Save Crystal River is doing. In a future post, we will look at how and why it’s so helpful to plant native vegetation.
I’ll see you on the water,
Walker A. Willis
The Acid Rain Pathway Diagram: The Team