Fig. 1.
Fig. 1.

Examples of different P sorbing technologies for addressing nonpoint P sources from agriculture, including (a) a preventive strategy whereby flue gas desulfurization (FGD) gypsum is applied to high P soils to immobilize water-soluble P and prevent P loss in surface runoff (photo credit: Ray Bryant); (b) two remedial strategies to remove dissolved P from soil water and shallow groundwater flow paths using a permeable reactive barrier filled with iron-coated sand (left) and enveloping a tile drain with iron-coated sand (middle and right) (photo credits: Wim Chardon and Gerwin Koopmans; see Chardon et al., 2012); and (c) a remedial strategy to remove dissolved P from concentrated surface flows in an agricultural drainage ditch using a FGD gypsum filter (photo credits: Ray Bryant; see Bryant et al., 2012).