Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Toxic flood lifts lid on common urban pollution problem


Broken sewers, flooded industrial plants and dead bodies are all likely to blame for poisoning the waters being drained from New Orleans.

But the water – and the muck it is leaving behind — also owes its contamination to a source as mundane as it is unexpected: Toxins common in most urban environments that made their way en masse into the water as it stagnated atop the city.

So says a University of Florida professor who has spent years studying the harmful contaminants that turn up in urban runoff, or rainwater that washes across streets and other hard surfaces in cities. Environmental engineering professor John Sansalone’s perspective is especially relevant because it is based on field research in New Orleans and Baton Rouge, where he was a professor at Louisiana State University before taking a job at UF this summer.

“What we see in New Orleans is that when you put a lot of water in contact with the urban environment, all the potential contaminants that stayed around in that environment are now back in the water – definitely, to our horror,” Sansalone said.

Federal and Louisiana officials continue to sound alarms about the contaminated waters and scum left behind by the retreating flood. Early September test results released late last week showed high levels of bacteria, lead and harmful levels of chemicals including arsenic, according to the Environmental Protection Agency.

While the sources of these and other contaminants remain under investigation, public scrutiny has focused on broken sewer pipes and other major failures in the city’s infrastructure attributed to Hurricane Katrina. Though these are certainly real problems, it’s also highly likely that the stagnant waters are contaminated because they’ve soaked up “legacy” pollutants that accumulated during normal conditions on the city’s streets, sidewalks, roofs and other impermeable surfaces, Sansalone said.

These pollutants, which normally appear in urban runoff, are more toxic than commonly understood, he said. In a study published last month in Water Environment Research, Sansalone and three co-authors report that runoff from an elevated section of Interstate 10 in Baton Rouge contained some contaminants at levels “greater than those found in untreated municipal wastewater from the same service area,” according to the study.

The findings were based on periodic analysis of runoff that drains off Interstate 10 into Baton Rouge’s City Park Lake just below the highway. Based on data first gathered in 1999, they revealed high levels of particulates, or microscopic- to millimeter-sized particles of material, as well as high chemical oxygen demand, an indicator of the presence of organic chemicals in oil, gas, grease, cigarette filters and other pollution.

Other research on urban runoff, meanwhile, has detected high levels of toxic metals and nutrients including phosphorus thought to leach from building materials, Sansalone said.

Organic chemicals are particularly dangerous to fish and other aquatic life because they reduce the levels of oxygen in the water, impinging on its ability to support life. Particulates cloud water, reducing sunlight penetration and plant growth. Once they cross a certain threshold, organic chemicals and metals also can be harmful to people.

New Orleans officials remain extremely concerned about bacterial contamination in the flood waters. Typically the result of contamination from untreated sewage, bacteria also can come from urban runoff, Sansalone said. Although it was not measured as part of his published study, other studies have found that such runoff contains heightened levels of bacteria stemming from bird and animal droppings, among other sources.

Sansalone said based on his studies of urban runoff alone, it’s critical that environmental officials scour the city of flood residue. “How we clean up this residual matter – which will not be easy – will be a chronic issue to the health of the city,” he said.

He said the contamination in New Orleans also highlights the need for other cities nationwide to do more to remove the toxins in urban runoff before, rather than after, it gets washed into waterways. There are several good strategies, he said. Increasingly affordable “permeable pavements” allow runoff to be stored, evaporate or percolate through pavement and into the ground, where soil and microorganisms can help filter the contaminants. Planting vegetation and especially trees also creates aesthetically pleasing buffer zones, providing storm water flooding control and other benefits. Finally, cities can use high-tech street sweeping equipment that is very effective at capturing pavement contaminants.

“If you pick up this potentially toxic material before it gets into the hydrological cycle, it is far more economical than if you try to take it out of the water after the fact,” he said.

John Sansalone | EurekAlert!
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>