But do the ordinances really help reduce phosphorus pollution? That's been an open question until now, says John Lehman, professor of ecology and evolutionary biology at the University of Michigan.
"It's one of those things where political organizations take the action because they believe it's the environmentally conscious thing to do, but there's been no evidence offered in peer-reviewed literature that these ordinances actually have a salutary effect," Lehman said.
Now, such evidence exists in a study published by Lehman and students Douglas Bell and Kahli McDonald in the journal Lake and Reservoir Management. The paper, published online Aug. 14, shows that phosphorus levels in the Huron River dropped an average of 28 percent after Ann Arbor adopted an ordinance in 2006 that curtailed the use of phosphorus on lawns. Phosphorus is naturally plentiful in southeast Michigan soils, so fertilizing established lawns with the nutrient is generally unnecessary.
Lehman was in an ideal position to assess the effectiveness of the Ann Arbor ordinance because he and undergraduate student Julie Ferris were already studying nutrient levels in the Huron River and two downstream lakes, Ford Lakes and Belleville Lake, for a different research project. Ferris used some of the data from that project in her senior honors thesis, and she and Lehman published a paper on the Ford Lake and Belleville Lake research, but they weren't sure what to do with the rest of the data from the Huron River around Ann Arbor.
"As we were talking about it, I got a phone call from Ann Arbor environmental coordinator Matt Naud, who knew about the work we had been doing," Lehman said. "He said the city council had enacted an ordinance that would reduce the use of phosphorus-containing fertilizers, and he wondered if we would be able to detect any change that might occur as a result."
Using statistical models, Lehman and Ferris figured out how much sampling would be required to confidently detect a 25 percent decrease in phosphorus concentrations. "We came up with the result that for most of the river that runs through Ann Arbor, we should be able to detect a change of that magnitude by sampling once a week for one summer or two summers, depending on the sampling station."
Naud found funding to pay a student to do the work over the next two summers. By that time, Ferris had graduated and gone on to medical school, so Lehman recruited Bell to do the sampling and chemical analyses. When Bell graduated and took a job measuring phosphorus on research cruises around Bermuda, McDonald joined the project.
"Right away, we started to see decreases," Lehman said. After the first year of data collection, it was clear that phosphorus concentrations were lower after the ordinance was enacted than before. But did the ordinance cause the drop? Though that explanation seems likely, public education efforts and general increased environmental awareness among Ann Arbor residents also may have entered in.
At any rate, the study already has attracted the attention of the Southeast Michigan Council of Governments (SEMCOG), which invited Lehman to present the study results at a meeting earlier this year, and may well generate interest beyond Michigan's borders.
"Although the science wasn't difficult, its ramifications in a political sense and in an environmental sense will not be insignificant," Lehman said.
The research was funded by the Environmental Protection Agency, the U.S. Department of Agriculture and the city of Ann Arbor.
For more information:
John Lehman: www.ns.umich.edu/htdocs/public/experts/ExpDisplay.php?ExpID=1018
Lehman's project web site: www.umich.edu/~hrstudy
Lake and Reservoir Management: www.tandf.co.uk/journals/titles/07438141.asp
Bioinvasion on the rise
15.02.2017 | Universität Konstanz
Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
24.02.2017 | Life Sciences
24.02.2017 | Life Sciences
24.02.2017 | Trade Fair News