WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



77 



is the chemical nature of the pesticide itself. The 

 chlorinated hydrocarbons have a very low solubil- 

 ity in water and tend to be adsorbed on clay par- 

 ticles and organic matter. Accordingly, these sub- 

 stances are very resistant to downward leaching. 

 The Wisconsin studies showed that a silt loam soil 

 retained 84 to 96 percent of these insecticides in 

 the surface 3 inches even after 17 months. 



Cooperative studies between the U.S. Depart- 

 ment of Agriculture and the Georgia agricultural 

 experiment station showed that the nature of the 

 soil could have a marked effect on the amount of 

 chlorinated hydrocarbon insecticide removed 

 under extended leaching with water. "When 40- 

 gram samples of six different soils were eluted 

 with 1.600 milliliters of water, the results were as 

 follows : 



(a) In genera], lindane was the one 

 most readily leached; 54 to 88 percent 

 of this chemical was removed from the 

 six soils. 



(5) Xo trace of endrin was found in 

 the leachate from three of the soils, but 

 51 to 95 percent of that added to the 

 other three soils was leached. 

 (<?) Dieldrin showed wide variability 

 in behavior among the six soils. Only 1 

 percent of the dieldrin was leached 

 from Magnolia sandy loam, whereas 65 

 percent was removed from Lakeland 

 sand. Results from the other four soils 

 were scattered in between these ex- 

 tremes. 



(d) Aldrin was very resistant to leach- 

 ing. Only a trace was removed from five 

 of the soils, and 16 percent from the 

 Lakeland sand. 



(e) Heptachlor also was very resistant 

 to leaching: none was found in the 

 leachate from four of the soils, and only 

 15 percent from the other two. 



"When one considers this divergent heterogene- 

 ity among six sandy soils found within a 50-mile 

 radius of Tifton, Ga., one can surmise what the 

 results would have been had a wide range of soils 

 from all over the United States been studied. 



In experimental plots in Texas where DDT, 

 benzene hexachloride (BHC), toxaphene, and 

 dieldrin were applied to soil and plowed to a depth 

 of 6 inches, about 20 percent of the amount applied 



was found present after 4 years, except for BHC 

 (1.5 percent of the amount applied was recovered) . 

 When granular dieldrin was applied at the rate of 

 10 pounds per acre (5 p.p.m. to plow depth) to 

 three kinds of soils, the residues recovered after 1 

 year were 14.2 p.p.m. dieldrin in the sandy soil, 

 4.7 p.p.m. in the medium-textured soils, and 2.3 

 p.p.m. in fine-textured soils. 



Experience has shown that whenever root crops — 

 potatoes, carrots, sugar beets — are planted in soil 

 containing aldrin or dieldrin, one can expect to 

 find residues of aldrin or dieldrin in these root 

 crops. Research information on the persistence of 

 insecticides in soils may be vital to a determination 

 whether major crops, such as alfalfa, sugar beets, 

 peanuts, and soybeans, can be planted without 

 hazard of contamination. 



Samples of well water and surface water from 

 the grounds of two U.S. Department of Agricul- 

 ture laboratories were analyzed by gas chromotog- 

 raphy. Chlorinated hydrocarbon insecticide had 

 been used in experimental spraying of livestock 

 for the control of insect pests for 17 years at one 

 laboratory and 2 years at the other. Xo insecticide 

 was found in any of the water samples. 



Analyses for DDT and its metabolites in sam- 

 ples of water from creeks and rivers in areas of 

 Idaho that had been sprayed to control spruce 

 budworm showed less than a 0.0002 p.p.m. of DDT 

 in 66 percent of the samples. Less than 2 percent of 

 the samples exceeded 0.0013 p.p.m. of DDT. 



Cooperative research in Oregon and Washing- 

 ton indicated that spraying forests for control of 

 the Douglas fir tussock moth with DDT at three- 

 fourths of a pound per acre resulted in a general 

 increase of DDT and its isomers in the food chain 

 of fish and animals. The highest residue, 1.2 p.p.m., 

 was found in trout and the lowest, 0.02 p.p.m., in 

 herbivores. 



The U.S. Department of Agriculture has car- 

 ried on a monitoring program to ascertain whether 

 insecticides are accumulating in soils and related 

 waters as a result of agricultural use. The rind, 

 are typified by results from a study near Green- 

 ville, Miss. 8 



* IVEBSON, L. K. MONITORING OF P 3 



watek in us. Presented :u Amer. Lss n A.dv. 



Sci. Meetings, Washington, D.O., Dec. 27, v.- 



