Source
Author: Lance Frazer
Publication: Environmental Health Perspectives · Volume 113, Issue 7 · Pages A456 – A462
https://doi.org/10.1289/ehp.113-a456
Excerpts
Runoff Effect on Nearby Habitats and Water Sources
“On a road of open-graded aggregate (stone), much of that material would seep down into the pavement and soil, and the community of microorganisms living there would begin a rapid breakdown process. But pollutants can’t penetrate an impervious surface [edit: like asphalt], and the rapid flow of rainwater off of impervious surfaces means these pollutants end up in the water. “So then,” says Ferguson, “not only do you have too much water, all moving too fast, you have polluted water that kills fish and makes water unfit for drinking or recreation.”
“Bannerman has spent the last 30 years studying stream flow and the effect of urbanization on watersheds, including the depletion of groundwater reserves. “Not allowing the rainfall to infiltrate back into the aquifer is a very serious issue,” he says. “If that happens, you lose the base flow [the portion of water derived from underground sources] for streams, and you lose the wetlands fed by springs. It’s a complete disruption of the hydrologic cycle.”.”
Asphalt Heat Island Impact on Wildlife
“A sudden thunderstorm striking a parking lot that has been sitting in hot sunshine (where surface temperatures of 120°F are not unheard of) can easily yield a 10°F increase in rainfall temperature. And that heated water isn’t coming off just one parking lot or one street, but more likely several, all adding heated water to a stream or river.
Many aquatic organisms, at different stages of their lives, are vulnerable to even small increases in water temperature. “I’ve seen trout streams in Wisconsin and elsewhere in the Midwest lose whole populations because of—at least in part—the rise in temperature caused by runoff from impervious surfaces,” “
Wilson says. “Increased temperature also decreases the water’s ability to hold oxygen…”
Contaminants in Asphalt and their Impact on Water and the Environment
Asphalt is one concern, as it contains coal tar pitch, a recognized human carcinogen, as well as polycyclic aromatic hydrocarbons (PAHs) including benzo[a]pyrene, another carcinogen…. The health risks of arsenic and chromium are well known, and while copper is not generally a human health risk, low concentrations of certain ionic forms of this metal are toxic to marine flora and fauna….
…As material ages and is exposed to high levels of sunlight, temperature extremes, chemicals in the environment such as salt from roads, and so on, leaching out will increase. If the pollutant source is a coating, then pollution levels decrease with age, but can still have a significant impact, she says. “If you look at the asphalt used in a parking lot, the top coat is quite toxic. So if you have a heavy rain [soon] after the parking lot goes in, it’s not unusual to see fish kills downstream.”
Lalor cites research published in volume 35, issue 9 (1997) of Water Science and Technology showing that stormwater from roofs and streets contributed 50–80% of the cadmium, copper, lead, and zinc measured in Swiss combined sewer system flows.”
Chemical Effects on Human Health
“The chemicals released can have a significant impact on environmental and potentially human health….
Some materials, such as metals, are especially toxic to fauna at various stages of their life cycle,” says Lalor, “while some organics, particularly petroleum-based organics, can function as pseudoestrogens. So while they may not cause death, they can trigger a significant disruption in the physiology of the organisms exposed to these pollutants…”