Composted sewage captures dirt's lead. (Environment).Lead-contaminated soil in urban parks, gardens, and schoolyards could be made safer by adding composted organic waste, new research suggests. The tactic could reduce the quantity of the toxic metal toxic metal Environment Any metal known to be toxic to humans–eg, antimony, arsenic, beryllium, bismuth, cadmium, lead, mercury, nickel. Cf Nontoxic metal. that moves from the soil to people, especially children, says Sally Brown Sally Brown is the younger sister of Charlie Brown in the comic strip Peanuts by Charles Schulz. Character Sally has flipped blonde hair with a cluster of curls and sometimes a bow in front, and she wears a polka dot dress, usually pink or blue. of the University of Washington in Seattle. Brown and her colleagues added biosolids--the polite term for byproducts of treated sewage Sewage Water-carried wastes, in either solution or suspension, that flow away from a community. Also known as wastewater flows, sewage is the used water supply of the community. It is more than 99. that are blended into fertilizers--to lead-tainted soil from a home garden in Baltimore. Then they fed rats food tainted taint v. taint·ed, taint·ing, taints v.tr. 1. To affect with or as if with a disease. 2. To affect with decay or putrefaction; spoil. See Synonyms at contaminate. 3. with various soil-biosolids mixtures. Of nine recipes, eight reduced the amount of lead absorbed into the animals' bones. Composted, iron-rich biosolids biosolids Sewage sludge, the residues remaining from the treatment of sewage. For use as a fertilizer in agricultural applications, biosolids must first be stabilized through processing, such as digestion or the addition of lime, to reduce concentrations of heavy metals and were most effective. When blended with nine times their mass in soil, these reduced by about 40 percent the quantity of lead later detected in the rats' bones, the researchers report in the January-February Journal of Environmental Quality. While it isn't yet clear how biosolids bind lead in soil, Brown suggests that heavily leaded urban yards could be rendered less dangerous with the addition of composted biosolids. The metal poses developmental risks for children, who inevitably consume some dirt as they play.--B.H. |
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