Whipsawing from droughts to downpours, heat waves to deep freezes, the state’s farmers are facing down an uncertain future.
In March, residents of Cape Town, South Africa stood in line for hours to buy drinking water at supermarkets or pump it from springs amid severe water shortages.
Credit: Dave Hensley/flickr<p>Those underground reservoirs are called aquifers. They fill naturally with rain or snow that seeps into porous ground--a process called aquifer recharge. When people drain an aquifer faster than nature can replenish it, it dries up.</p><p>Water utilities have practiced managed aquifer recharge--intentionally sending water underground to refill aquifers that are running low--for decades. Managed aquifer recharge can be done with injection wells or infiltration ponds that help direct water underground. </p><p> In California, for instance, large basins in Los Angeles infiltrate hillside runoff into aquifers. </p><p>But hillside runoff is different than urban runoff. For starters, hillside runoff is a lot cleaner and carries fewer of the pollutants that urban storm water can pick up. Small-scale green infrastructure arrangements such as rain gardens, permeable pavement and vegetated swales now are common in many cities. Still, "we don't have a lot of experience capturing and percolating large quantities of urban runoff into the ground," Luthy said. </p><p>But three promising new technologies could help make it a reality.</p>
Credit: Simon Dooley/flickr<p>Luthy and others are experimenting with biochar to scrub out some types of storm water pollutants. He's teamed up with Sedlak to create a system that combines biochar and manganese-coated sands to see whether the combination can further enhance the removal of organic pollutants related to automotive use and insecticides and herbicides from urban storm water. Biochar is plant or wood material that's roasted at high temperatures until it turns into charcoal.</p><p>There's been a lot of buzz in recent decades about potential uses of carbon-rich biochar to simultaneously boost soil fertility and store planet-warming carbon dioxide in the ground. But it turns out biochar may also be good at absorbing heavy metals and other trace organic pollutants from urban runoff. </p><p>"Think of it as a big carbon drinking water filter for storm water," Christopher Higgins, an environmental chemist at Colorado School of Mines in Golden, Colorado told EHN. </p><p> Higgins now is experimenting with biochar to remove a particularly tricky family of drinking water pollutants, called perfluoroalkyl substances (PFASs) from urban runoff. These man-made chemicals are found in stain repellants, paper coatings and firefighting foams.</p>
Preliminary tests of a plant biofilter pilot project in Kfar Sava, Israel, using local plants and soils, found that the rain garden was able to effectively treat heavy metals and nutrients in urban runoff and meet Israeli guidelines for aquifer recharge. (Credit: Ana Deletic)<p>In some water-stressed regions, scientists and engineers are working to optimize the use of plants to remove nutrients, such as nitrogen and phosphorus from storm water. High levels of these nutrients in ground and surface water can lead to algal blooms and harm drinking water sources.</p><p>Ana Deletic is a water-engineering expert at the University of New South Wales in Australia. She has helped to engineer massive rain gardens in Australia, Israel and China--some up to an acre in size--to help filter these common pollutants out of urban wastewater. </p><p>"These are simple-looking systems, but they are not. They are living machines that must be tailored for local conditions," Deletic told EHN.</p><p> Many urban environments have a history of contamination with toxic metals including lead and cadmium. Deletic said that zinc from rusting metal roofs has become a public health concern in some cities in Australia and New Zealand. Plants may be able to help remove heavy metals, too. "Plants need small amounts of metals to grow, so over time they will suck up some of these contaminants," said Deletic.</p><p>Finding the right plants and right soils to remove pollution can be challenging. "In general, what we've found is that plants with long, fine root systems tend to work best for nitrogen and phosphorus removal," she said. </p>
A new study found levels of the widespread herbicide and its breakdown products reduced, on average, more than 70 percent in both adults and children after just six days of eating organic.
"Many of the chemical profiles that we see in cetaceans are similar to the types of chemical profiles that we see in humans who live in those coastal areas."
A new study found that animals known to carry harmful diseases such as the novel coronavirus are more common in landscapes intensively used by people.