Fig. 6. Correlation of (a) peak concentrations above a threshold of 1 x 10^–3 mg L^–1 with (b) surface organic carbon and (c) soil texture. In (c), 1 = sand, 2 = loamy sand, 3 = sandy loam, 4 = loam, 5 = silt, 6 = silt loam, 7 = sandy clay loam, 8 = clay loam, 9 = silty clay loam, 10 = sandy clay, 11 = silty clay, and 12 = clay.