found: Pennsylvania Dept. of Environmental Protection, Nutrient Trading:Web Page [ http://www.dep.state.pa.us/river/river_trading.htm ] , June 5, 2006 ("Nutrient Trading [is] Exchange of pollutant reduction credits between sources to meet regulatory objectives or water quality goals; Harnessing market forces to achieve environmental goals; As a buyer, you pay or otherwise arrange for someone else to meet or exceed your environmental obligation; As a seller, you exceed your own environmental obligation and benefit from it")
