No abstract

14 C-p,p'-DDT-bound residues in soil can be released by treatment with concentrated sulphuric acid at ambient temperatures. Within 6 days, about 70% of the bound residues was released. Bound residues released after 9 months incubation with 14 C-DDT showed the presence of DDT and DDE only while bound residues released after 18 months, contained in addition 13% DDD.Release of bound 14 C-residues also occurs readily following inoculation of the soil-bound residues with fresh soil or with individual microorganisms.Almost complete release of bound residues was observed after incubation for 45 days. The rate of release was rapid during the first two weeks and decreased thereafter. TLC and HPLC analysis showed that the released residues contained DDE (about 80%) and a smaller amount of DDD. The disappearance of DDT from the released residues may be attributed to its microbiological degradation to DDE and DDD, shortly after its release.

A model ecosystem has been used to evaluate the 14 impact of C-lindane on rice-fish agricultural system. 14 The distribution of C-residues among the constituents of the model ecosystem was studied over a period of 90 days. The insecticide was found to be readily absorbed by the roots and translocated to all parts of the rice plant. The peak level in the shoots (26 ppm) and roots (105 ppm) of plants was reached to within three weeks. Lindane was concentrated in fish and residues as high as 90 ppm could be detected after 30 days.The major part of the residues present in the different constituents of the ecosystem could be extracted with hexane and proved to contain soley the parent compound. The data obtained show that lindane possesses a relatively low biodegradability in fish and

The distribution of 14 C-Carbofuran residues among the constituents of a model rice-fish ecosystem was studied over a period of 90 days. Carbofuran was readily absorbed from the root system and distributed to all parts of the rice plant of the different constituents of the model ecosystem, rice plants contained the highest concentration of 14 C-residues. The results obtained indicate that carbofuran does not accumulate in fish to an appreciable extent. In water, the parent compound decreased appreciably with time and contributed about 10% of the total 14 C-residues after 30 days. Analysis of residues in fish, plant and soil showed, apart from the parent compound, the presence of several metabolites (60% of residues).Among the degradation products, 3-hydroxy carbofuran and carbofuran phenol were identified as major metabolites.