Dieldrin in soil

The gas chromatographic procedure described by Woodham et al. [8] and discussed in section 9.1.1.1 for the determination of Aldrin, Endrin and Dieldrin in soils has also been applied to sediments. 

Robertson, B.K. and M. Alexander. 1998. Sequestration of DDT and dieldrin in soil disappearance of acute toxicity but not the compounds. Environ.Toxicol. Chem. 17 1034-1038. 

Aldrin and dieldrin in aqueous solutions were chemically oxidized in the presence of ozone or air (292). Aldrin, dieldrin, and endrin were catalytically decomposed when mixed with acid clays but not by neutral clays (287) aldrin was oxidized to dieldrin in soil systems (248, 249, 250). Barlow and Hadaway (275) found that dieldrin was not decomposed when it was applied to dried mud blocks. 

Soil Organic Matter Organic compounds may exist in soil either in solution or the vapor phase and can be absorbed through the roots in either state, absorption from solution would be the most likely process. From the discussion of the sorption process in soil (see Sorption, Chapter 3) the concentration of the compound in aqueous solution, Caq, would be a function of the concentration in the soil (Csoii). and the soil distribution ratio, K, which in turn is dependent primarily on SOM content. One would predict that uptake would be inversely related to the level of SOM. Observations of the uptake of diel-drin by carrots raised in different soils provide an opportunity to evaluate this relation and demonstrate the dependence on the concentration of the compound in soil solution. If the uptake efficiency is defined by the ratio of the concentration of dieldrin in carrots to that in the soil it is clear that higher levels of soil organic matter reduce uptake by carrots (Table 5.6). The ATom for dieldrin is 6980 mL g from which values were calculated for dieldrin in each soil. Since = Cjoii/Caq the concentration of dieldrin in soil solution can be determined. If uptake is defined as Ccarrot/Caq consistent value... 

As mentioned earlier (Figure 5.5), aldrin and heptachlor are rapidly metabolized to their respective epoxides (i.e., dieldrin and heptachlor epoxide) by most vertebrate species. These two stable toxic compounds are the most important residues of the three insecticides found in terrestrial or aquatic food chains. In soils and sediments, aldrin and heptachlor are epoxidized relatively slowly and, in contrast to the situation in biota, may reach significant levels (note, however, the difference between aldrin and dieldrin half-lives in soil shown in Table 5.8). The important point is that, after entering the food chain, they are quickly converted to their epoxides, which become the dominant residues. 

The general picture, then, is that pyrethroids are reasonably persistent in soils and sediments but not to the same degree as OC compounds such as dieldrin and p,p -DDE. They do undergo bioconcentration from water by fish and other aquatic... 

Woodham et al. [8] converted Dieldrin and Endrin to chemical derivatives prior to gas chromatographic determination of these substances in soil and sediments. An aliquot of extract after appropriate clean-up and evaporation... 

Novikova [21] has reviewed the literature (209 references) covering the extraction, clean-up and analysis of organochlorine (and organophosphorus) insecticides in soil. Johnson and Starr [22] and Chiba and Morley [4] have studied factors affecting the extraction of Dieldrin and Aldrin from different soil types ultrasonic extraction was recommended by these workers. Lopez-Avila et al. [23] used microwave assisted extraction to extract chlorinated insecticides from soils. 

The procedure described by Suzuki et al. [11, 12], discussed in section 9.1.1.1 for the determination of chlorinated insecticides in soils has also been applied to hexane extracts of river sediments using high-resolution gas chromatography with glass capillary columns. Minimum detectable levels of a-BHC, fs-BHC, -BHC, P-BHC, Heptachlor, Heptachlor epoxide, Aldrin, Dieldrin, Endrin, p,p -DDE, p,p -TDE and p,p -DDT in lOOg samples of bottom sediment were 0.0005, 0.0032, 0.0014, 0.0040, 0.0012, 0.0020, 0.0014, 0.0020, 0.0056, 0.0032, 0.0080 and 0.0120mg kgr1 respectively. 

Soil. Dieldrin is very persistent in soil under both aerobic and anaerobic conditions (Castro and Yoshida, 1971 Sanborn and Yu, 1973). Half-lives in soil ranged from 175 d to 3 yr (Howard et al, 1991 Jury et al., 1987). 

Microorganisms isolated from a loamy sand soil degraded lindane and some of the metabolites identified were pentachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, y-PCCH, y-TCCH and p-3,4,5,6-tetrachloro-l-cyclohexane (p-TCCH) (Tu, 1976). y-PCCH was also reported as a metabolite of lindane in an Ontario soil that was pretreated with jo,//-DDT, dieldrin, lindane, and heptachlor (Yule et ah, 1967). The reported half-life in soil is 266 d (Jury et al., 1987). 

Volatilization rates were much less where the pesticides were incorporated even to shallow depths in soil. Incorporation of heptachlor, dieldrin, or trifluralin to the 7.3 cm depth reduced losses to less than 7% in 90 to 167 days—volatilization rates 3 orders of magnitude less than those for exposed residues of the same pesticides. 

Eye, J.D. (1968) Aqueous transport of dieldrin residues in soils. J. Water Pollut. Control Fed. 40, R316-R332. 

Pesticides in soils can also be remediated. Table 10 summarizes some results from a project where soils from Hawaii and Virginia, contaminated with DDT, DDD, DDE, and dieldrin, were treated with Na/NH3. In all... 

As an example of differences in soil residue persistence between the organophosphates and chlorinated hydrocarbon pesticides, parathion and malathion residues were present at the 0.1 p.p.m. level within 8 days of application whereas aldrin [according to Lichtenstein (23)] when applied at the same concentration, persisted 5 months longer as did aldrin and dieldrin at 40% of the applied dosage. Decker et al. (12) report that aldrin and dieldrin residues in soils never exceeded 13.2% of the total applied when tested one year after the last application. Other workers (24) have reported that on a loamy soil, under existing weather conditions, aldrin and dieldrin residues were present at a level of approximately 20% of the total applied insecticidal dosage over a 5-year period. 

Insecticides tend to persist longer in soils of high organic matter. In fact, in muck soils (50% or more organic matter), residues have been found bound to soil particles to such an extent that the same amount of toxicant is less effective in muck soil as compared with a sandy type. It has been noted that pesticides are absorbed into crops most readily from sandy soils and least from muck soils. Moisture enhances the release of volatile pesticides from soil particles and also influences the breakdown of other toxicants. Microbial attack has been found to oxidize aldrin to dieldrin, and parathion in the presence of yeast is reduced to the nontoxic aminoparathion in soil. As might be expected, increased soil temperatures can dramatically increase the rate of pesticide loss owing to volatilization and increased breakdown. Cover crops, such as alfalfa, can decrease pesticide volatility from soil whereas cultivation... 

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