Fig. 4 Equation [3] estimates for the minimium DOC_o concentrations needed to produce a 2% decrease in pesticide sorption, i.e., K^S_i,DOC 0.98 f_SOCK^SOC_i for values of K_D (f_SOC* K^SOC_i) < 20 L/kg (upper graph); and for a case where K_D (f_SOC* K^SOC_i) is near unity, K^S_DOC = 0 and K^DOC_i = 100 and 200 (lower graph)