Bimodal distribution of organochlorine insecticide levels in soil due to emulsion spraying

Concentrations (c) of lindane and technical DDT have been determined in about 60 soil samples, randomly taken from a 10 × 10 m² plot of bare soil one day after spraying. These experimental c, log c data, and literature data for dieldrin are used to examine the various residue distributions in cultivated and uncultivated soil plots. The normality of these distributions is examined with some statistical tests. All c distribution curves are more or less skew to higher c levels. From the pooled cumulative distribution curve and frequency histogram it is concluded that the found c distributions can be characterized best as bimodal.

Finally, some practical recommendations are given for cost‐effective soil sampling.