

SSS 

p;p'-DDT, and o,p'-DDT. These residues made up more 
than 94% of all organochlorine insecticides present in the 
soil and 97% in the earthworms. The remaining 
percentages were composed of dieldrin, heptachlor 
expoxide, and y-chlordane. Small amounts of y-BHC were 
detected early in the study; no 0,p'-DDE or o,p'-DDD 
were detected in the samples. 
Levels of DDT compounds in soils and earthworms are 
presented in Figs. 2 and 3, each line representing the arith- 
metic mean of two replicates. There were no significant 
differences between replications for any of the compounds 
in either soils or earthworms. Differences among treat- 
ment levels were significant (P < 0.01) for all compounds 
in soils and earthworms, All DDT compounds in soils and 
p,p'-DDT and p,p'-DDE in earthworms increased linearly 
(P < 0.01) with increasing levels of application. The 
relation of p,p'-DDD in earthworms to amounts of DDT 
applied was parabolic, as were the relations of the DDT 
totals with and without DDE; all residues increased at an 
accelerating rate with increasing levels of application. 
Parabolic trends also were present for p,p'-DDT and 
p,p'-DDE in earthworms but they were not significant. It 
would appear that earthworms accumulated quantities of 
DDT and metabolites at a rate that was geometrically 
related to the levels of application. 
Amounts of p,p'-DDE in soils were at a minimum in the 
early sampling periods and gradually increased to a 
maximum at 2 years (Table 2 and Fig. 2B); the increase 
was linear with time (P < 0.01) for each treatment level 
(Table 4). No distinct time trend of increase or loss of the 
other components or their totals was evident from the fluc- 
tuations of soil residues (Table 2) or from the simple linear 
regressions (Table 4). 
Differences among sampling periods were significant 
(P < 0.01) for all DDT compounds in earthworms 
(Table 3). Quantities of p,p’-DDT reached respective 
maxima of 2.6, 2.0, and 28.0 ppm for 0.56, 2.24, and 
8.97 kg ai/ha plots by 1 month after application and de- 
creased to a minimum by 10 months. No significant fluc- 
tuations occurred during the remainder of the 2 years. 
Maximum p,p’-DDE values in earthworms of 1.8, 12.5, 
and 23.0 ppm from 0.56, 2.24, and 8.97 kg ai/ha plots 
were reached 2 months after application; p,p'-DDE then 
varied from a low in January to a high in September to 
another low in January and to a high in May. The subse- 
quent elevations were greater than the troughs but less 
than the maximum achieved 2 months after application. 
Maximum p,p'-DDD levels of 6.4 ppm from 0.56 kg ai/ha 
plots occurred in the initial sampling, 8.8 ppm from 
2.24-kg plots at 4 months, and 89.0 ppm from 8.97-kg 
plots at 2 months. However, no significant decline 
occurred until after 4 months when a pattern of elevations 
and troughs was evident with lows in January and highs in 
May. Generally, the highs and lows were different from 
each other and less than the maximum. The patterns for 
both DDT totals (with and without DDE) were similar to 
that for p,p’-DDD, except that all maximums for DDE + 
ee 
ae HY apes P 
PRE é 
ae: 
\ 
— 
4 8 12 16 20 24 
TIME SINCE APPLICATION, MONTHS 
TOTAL DDT & METABOLITES, PPM--DRY WEIGHT 
Fig. 3. Mean quantities of total DDT and metabolites in soils 
(solid lines) and earthworms (broken lines) at various times fol- 
lowing a single application of 50% wettable powder DDT at 
0.56 (circles), 2.24 (squares), or 8.97 (triangles) kg ai/ha. 
DDD + DDT occurred 2 months after sampling when 
values averaged 5.8, 19.5, and 131.0 ppm from 0.56, 
2.24, and 8.97 kg ai/ha plots. 
All residues in earthworms declined during the 2-year 
study. The decline of all compounds except p,p’-DDE was 
linear with time (P < 0.01) for all treatment levels (Table 
4). The levels of p,p'-DDE in earthworms after 2 years 
were less than the maximum found 2 months after DDT 
application (Table 3) but were not significantly linear 
with time (Table 4). 
Linear correlations over the 2-year period between 
DDT metabolites (or their totals) in earthworms and 
quantities in soils were not significant. The low level of 
correlation probably was due, as with dieldrin, to the resi- 
dues fluctuating seasonally in earthworms but not in soils. 
Correlations were much greater, as with dieldrin, for sam- 
ples collected within one season, and most were signifi- 
cant. 
Ratios of residues in earthworms to residues in soils, 
expressed as ppm dry weight in earthworms divided by 
ppm dry weight in soils, were examined for differences 
(Table 5). Generally, the ratios were significant only 
when the residue levels in earthworms reached a 
maximum. When p,p'-DDT in earthworms was at a maxi- 
mum, the compound was 12.3 times that in the soil and 
was significantly greater than at other times, but after 8 
months, p,p'-DDT was generally higher in soils than in 
earthworms. After 2 weeks, p,p'-DDE in earthworms was 
