Increased runoff has negative effects on waterways
November 12, 2020
Plants have helped cool the atmosphere, but with rising carbon dioxide and ozone levels, there is little to stop the increase in runoff.
When they get hot, plants release water vapor in a process called transpiration, similar to sweating. They also take in carbon dioxide during photosynthesis. The decrease of carbon dioxide in the atmosphere creates a cooling effect, according to the National Aeronautics and Space Administration (NASA).
Studies show that increasing carbon dioxide has caused plant stromata, similar to pores, to contract and release less water by transpiration. As a result, plants are taking in less water from the environment.
Even though there has been less rainfall over land in recent decades, plants releasing less water has increased the amount of runoff.
“With less water being taken up by plants, more water is available for groundwater or runs off the land surface into lakes, streams, and rivers,” according to NASA. “Along the way, it accumulates excess nutrients and pollutants before emptying into waterways, where it affects the health of fish, algae, and shellfish and contaminates drinking water and beaches. Excess runoff can also contribute to flooding.”
Another effect of climate change is that an increase in ozone has also contributed to an increase in runoff. Higher levels of ozone have a similar impact as carbon dioxide, leading to less transpiration and more runoff.
In the San Francisco Bay, stormwater runoff is the largest source of pollution. Groups like San Francisco Baykeeper and Save the Bay advocate for policies to keep storm drains free of trash and other pollutants to keep the Bay clean and protect wildlife from contamination.
The Bay is rich in nutrients, containing comparatively higher concentrations of nitrogen and phosphorus than other estuaries. In turn, this poses a threat to creating harmful algal blooms that can potentially toxicate its water sources.
Such algal blooms may lead to decreased oxygen levels within the Bay, leaving aquatic life with little support. Lower oxygen levels will impact the growth of phytoplankton the most as nitrogen discharge increases with wastewater treatment.
Nutrient pollution creates an issue, as too much nitrogen and phosphorus in air concentrations lead to imbalanced water ecosystems. Ultimately, this affects the quality of water and food sources, creating environments in which water life depends for survival.
However, the Bay Area’s water sources aren’t out of hope.
Because of this danger, new methods of nitrogen removal will come into play. Solutions like wastewater recycling can also bring other benefits, such as protection from rising temperatures. They may also help reduce the dangers associated with rising sea levels and carbon dioxide storage.
Furthermore, the San Francisco Bay seems to resist the environmental issues relating to nutrient pollution due to various factors regarding higher filter levels by clams and increased mix tides.
Nonetheless, algal blooms are still a potential threat to the Bay. They may toxicate water sources, in some cases killing water life. Algae can contaminate all levels of the food chain and harm mammals, fish, and even humans.
Even in nontoxic cases, the blooms may deplete oxygen levels in the water and impact its quality. The Bay’s resilience may be historically significant, but it is also evident that such strength is breaking down.
“Considering the changing conditions in San Francisco Bay, uncertainty about future monitoring programs, and new nutrient policies on the horizon,” according to Progress Tracking by the San Francisco Estuary Institute. “there is a strong need for a coherent nutrient science and management strategy for the Bay.”