25 jun, 2018
Storms, manure and climate change
“On June 6, 2018, the Centre for Limnology (CFL) at the University of Wisconsin-Madison reported that a toxic algae bloom had begun to spread across Lake Mendota. It quickly led to the closure of beaches around Madison’s largest lake”.
An article posted at http://www.feedstuffs.com/news/heavier-rains-manure-mean-more-algae-blooms showed that there was a clear connection between phosphorus laden runoff from agriculture and the increased frequency of algal blooms in the surrounding lakes and rivers.
Large storm events have been identified as the cause agricultural runoff in the form of manure, delivering slugs of dissolved phosphorus to algal cells in the waterways. The high concentration of dissolved phosphorus in the water, leads to the proliferation of algal blooms.
The study showed that large storm events in the Madison, Wisconsin area had increased in frequency from 9.5 events per decade between 1930 and 1990, to 18 events per decade between 1991 and 2010.
“This runoff may be getting worse, according to a recent study from researchers with the Water Sustainability & Climate Project at the University of Wisconsin-Madison.
Not only have the number of storms events doubled, but they seem to be delivering large amounts of phosphorus to the lakes over a short period of time.
The authors of the study found that “with a changing climate, the frequency of high-intensity rain events is on the rise. These storms bring heavy rains over a short period of time and exacerbate phosphorus runoff from manure-covered agricultural fields, more so than scientists expected.74% of the phosphorus load in Lake Mendota is now delivered across just 29 days each year, and a 2016 study from scientists at Marylhurst University in Oregon and the University of Wisconsin-Madison showed that annual precipitation in the Yahara watershed, which includes Lake Mendota, increased by 2.1 mm each year between 1930 and 2010.”
Phoslock Water Solutions Ltd’s product, Phoslock, binds dissolved phosphorus to form the inert mineral, Rhabdophane. Once bound, the phosphorus is no longer available for uptake by algae. The addition of Phoslock to water will assist in the management of the phosphorus concentration in lakes.