Organochlorine pesticides degradation

Guo et al. reported that trace amoimts of aqueous organochlorine pesticides, such as hexachlorocyclohexane (HCH), could be totally degraded and mineralized into CO2 and HCl by near-UV irradiation of a suspension of Mg/Al LDH intercalated with paratungstate anions [108]. They demonstrated that photocatalytic degradation of the pesticide occurs in the interlayer galleries. It was also found that Zn/Al/W(Mn) mixed oxides, formed by calcination of POM-intercalated Zn/Al LDHs [109], exhibited higher photocatalytic activity in the degradation of HCH compared with the POM-LDH precursors. 

Kaneda, Y., Nakamura, K., Nakahara, H., and Iwaida, M. Degradation of organochlorine pesticides with calcium hypochlorite [Chemical Abstracts 82 94190e] /. ElselKagaku, 20 296-299, 1974. 

The organochlorine pesticides are considered persistent chemicals. Degradation is quite slow when compared with other pesticides, and bioaccumulation, particularly in aquatic ecosystems, is well documented. Their mobility in soil depends on the composition of the soil the presence of organic matter favors the adsorption of these chemicals onto the soil particles, whereas adsorption is poor in sandy soils. Once adsorbed, they do not readily desorb. These compounds induce significant abnormalities in the endocrine balance of sensitive animal and bird species, in addition to their adverse impact on humans, and their use is appropriately banned in most areas. 

Several intermediates have been identified in the process of pesticide degradation, unlike degradation of volatile organochlorine compounds. Stability... 

Figure 4.13 Variability in enantiomer fractions (EFs) of cis-chlordane and trans-chlordane at plots In grassland (G) and woodlands (W1 and W2) In Scotland. Box plot defined as follows top and bottom of whiskers are maximum and minimum EFs, respectively top and bottom of box are 25 and 75% percentiles, respectively line in box is median EF. (Reproduced with permission from Environmental Science and Technology, Enantioselective Degradation of Organochlorine Pesticides In Background Soils Variability In Field and Laboratory Studies, by Perihan Binnur Kurt-Karakus, Jacqueline L. Stroud et af, 41(14), 4965-4971. Copyright (2007) American Chemical Society)...

Kurt-Karakus, P.B. Stroud, J.L. Bidleman, T. Semple, K.T. Jantunen, L. Jones, K.C., Enantioselective degradation of organochlorine pesticides in background soils Variability in field and laboratory studies Environ. Sci. Technol. 2007, 41, 4965-4971. 

DEGRADATION OF ORGANOCHLORINE PESTICIDES IN PORK FAT BY -IRRADIATION CO SOURCE IRRADIATION DOSE = 0, 2.5 AND 5.0 KGY). 

The residues of dieldrin were the highest of all the organochlorine pesticides analysed, with concentrations ranging from 36.42 and 43.4 pg/kg. Compared with the values detected for aldrin, whose concentration ranged between 25.16 and 30.36 pg/kg, the high levels of dieldrin were attributed to degradation of the latter. 

Recent observations of the global distribution of persistent contaminants such as PCBs and some organochlorine pesticides emphasize the importance of defining the tendency of compounds to move into the vapor phase. This transition not only provides access to active degradation processes (see Photochemical Processes, Chapter 6), but it also results in a broader distribution through the influence of atmospheric processes. The PCBs and related compounds would not be considered volatile by usual criteria, however, it will be demonstrated that evaporation of a compound is influenced by its environment that is, compounds that might have little tendency to evaporate as the pure compound may be lost rapidly from water. Also, the magnitude of the response may reflect the area over which the compound is distributed. 

Organophosphate wastes may be effectively destroyed by incineration process. Unlike some organochlorine pesticides, such as, DDT, chlordane or dieldrin, the organophosphates do not tend to persist in the envi-ronment for long. They are susceptible to degrade by hydrolysis, oxidation and other processes. Also, they can break down in the aqueous media when exposed to x-ray irradiation. Trebse and Arcon (2003) have reported that diazinon [333-41-5] hydrolyzed to... 

Kaneda, Y., K. Nakamttra, H. Nakahara, and M. Iwaida. Degradation of Organochlorine Pesticides with Calcittm Hypochlorite, in Chem. Abstr. 82 94190e, I. Eisei Kagakn, 20 296-299 (1974). 

---