Lindane coefficients

Table I shows the results of calculating a soil diffusion coefficient and soil diffusion half-lives for the pesticides. The 10% moisture level specified means that the soil is relatively dry and that 40% of the soil volume is air available for diffusion. Complete calculations were not made for methoxychlor, lindane, and malathion because, based on Goring s criteria for the Henry s law constant, they are not volatile enough to diffuse significantly in the gas phase. This lack of volatility is reflected in their low values of X. These materials would move upward in the soil only if carried "by water that was moving upward to replace the water lost through evapotranspiration at the surface. Mirex has a very high Henry s law constant. On the basis of Goring s criteria, Mirex should diffuse in the soil air but, because of its strong adsorption, it has a very large a and consequently a very small soil air diffusion coefficient. The behavior of Mirex shows that Goring s criteria must be applied carefully.

The binding constants of a number of compounds were measured using dialysis, solubility and sorption techniques. The solubility technique was used for compounds which were not radiolabeled. All data was collected at pH = 8.3. The binding constants were then compared to the octanol/water partition coefficients for the compounds and the molar solubilities of the compounds. The data is presented in Table II. The Kow values were taken from the literature.18 22-2 The solubility values were determined in this research with the exception of DDT and Lindane, which were taken from the literature. A plot of log Kc vs. log Kow is presented in Figure 5. The slope of this line is 0.71, the intercept is 0.75 and the value of the correlation coefficient is 0.9258. The regression is highly significant... 

The data presented here indicates that the extent of binding for a particular compound is related to the octanol/water partition coefficient for that compound. This is very similar to the sorption of compounds from water to sediment. Compounds with log Kow values less than four (such as Lindane) will probably not be bound to an appreciable extent in the environment. Compounds with very high log Kow values (DDT and DEHP) may be bound to a significant extent. The extent of binding will depend on both the concentration of humic material and on the nature of the humic material. The humic materials used in this research showed dramatically different affinities for DDT. The reasons for this are poorly understood and deserve further study. 

Fig. 5. Relationship between the distribution (partition) coefficient on dimethyl dihydrogenated tallow montmorillonite for a range of non-ionic organic pollutants and their corresponding solubility in water. BHC is benzene hexachloride, the y-isomer of which is known as lindane aroclor 1232 and aroclor 1252 denote mixtures of polychlorinated biphenyls containing about 32 and 52% chlorine, respectively. After Beall (2003).

As an example, we can compare the solubility of lindane and 2,4-D pesticides with respect to their major loss pathways. The Ku values of these pesticides are 1.33 x 1CT4 and 5.5 x 10 9 mol L 1, respectively. In addition, the retardation coefficient or degree of sorption of lindane is much higher than that of 2,4-D. Therefore, 2,4-D is more likely to be leached, whereas lindane is more likely to remain near the soil surface from whichit can vaporize. Volatilization is thus the major pathway of lindane, and degradation and leaching are the major loss pathways of 2,4-D in the Asian environments. 

Plots of t0/t for varying [Q]T are first otained for different concentrations of lipid. Then, form the slope and intercept of a plot of k pp against am, the value of the partition coefficient is obtained. This method has been applied to the partitioning of lindane into lipid bilayers.(102 103) An example is shown in Figure 5.4 for the quenching of DPH by 5-DOXYL-decane in dimyristoyl-phosphatidylcholine vesicles(104) the increase in the partition coefficient as the... 

Illustrative Example 5.1 Deriving Liquid Aqueous Solubilities, Aqueous Activity Coefficients, and Excess Free Energies in Aqueous Solution from Experimental Solubility Data Problem Calculate the Cf (L), yf 1 and G of (a) di-n-butyl phthalate, (b) y-1,2,3,4,5,6-hexachlorocyclohexane (y-HCH, lindane), and (c) chloroethene (vinyl chloride) at 25 °C using the data provided in Appendix C. 

At concentrations normally encountered in environmental situations, sorption often has been observed to be relatively non-competitive. For example, Chiou et al. (1983, 1985) found no competition in the sorption of binary solutes m-dichlorobenzene and 1,2,4-trichlorobenzene and between parathion and lindane. MacIntyre and deFur (1985) measured the sorption of methyl and dimethyl naphthalene, individually and as components of JP-8 and synthetic jet fuel mixtures on two sediments and montomorillonite clay in water. The sorption coefficients of the naphthalenes generally varied by less than a factor of two. 

Reported vapor pressures of lindane at various temperatures and the coefficients for the vapor pressure equations... 

Reported octanol-water and octanol-air partition coefficients of lindane (y-HCH) at various temperatures... 

Fig. 9. Relationship between the steady-state bioconcentration factors on a lipid basis (BCFl) of chemicals in different fish species and the n-octanol/water partition coefficient (Kqw) (log/log scale). ( ) Solid circles are chemicals with known endocrine-disrupting properties. Abbreviations of the chemicals p,p -DDT 2,2-bis-(p-chlorophenyl)-l,l,l-trichloroethane. OCDD octachlorodibenzo-p-dioxin. TCDD tetrachlorodibenzo-p-dioxin. HCB hexachloro-benzene. PCA pentachloroanisole. PeCB pentachlorobenzene. MX musk xylene. TeCB tetrachlorobenzene. NP nonylphenol. TCB tetrachlorobenzene. y-HCH y-hexachlorocyclo-hexane (Lindane). PCP pentachlorophenol. DCB dichlorobenzene. BPA bisphenol-A. PCBs polychlorinated biphenyls...

Pentachlorophenol and lindane were selected primarily because they were reported to be the least mobile chemicals in fact, based on their octanol/water partition coefficients, it was expected that these chemicals would not leach at all. These chemicals were spiked into the soil at 16.2 ppm and were leached for 30 days with organics-free water at a rate of 55.8 mL/day. Results are presented as amount leached versus time and concentration of chemical in soil at various depths in soil column. Furthermore, mass balances are presented for each chemical. Subsequent sections present the experimental details and the results of this experiment. 

These data indicate that the tendency to distribute into the DOM varies both with the nature of the compound and the DOM. The soil humic acid was a more effective receptor and the magnitude of the Adom was directly related to the octanol-water partition coefficient, Aqw, which is also an index of a compound s tendency to distribute into a hydrophobic environment. Experiments with 1,2,3-trichlorobenzene (log Aqw = 4.14) and lindane (log = 3.70) did not give the same degree of solubility enhancement. Note that the distribution constant for DDT based on organic carbon, A[Pg.32]

Skin-saline partition coefficients for parathion and lindane in Fisher rats are listed in Table 2. Whole skin from the back was used after the subcutaneous fat and muscle were removed using a razor blade. Tissue was equilibrated for 18 h in solutions, which were subsequraitly filtered and analyzed. Partitioning into the skin was detCT-mined by change in the solution concentration. 

Example 3.4 Compare the rate of migration of lindane (C HgClg) and endrin (Cl HgCl O) with respect to groundwater seepage velocity in the sediments with organic matter content of 0.3%, porosity 0.3% and bulk density 1.9 g em We find the values of the partition coefficients of insecticides between the water and the carbon of organic matter of sediments K j which are 5.250 ml g for lindane and 89,100 ml-g" for endrin. 

A series of calibration or working standards were prepared from the metha-nolic stock solution containing lindane. This stock solution was prepared by carefully weighing out pure solid lindane on an analytical balance. These standards were injected into the C-GC-ECD from lowest to highest lindane concentration. The peak at 1.8 min was identified as a reference peak in the Turbochrom software and a narrow window was defined around the t[i ] of the apex of the peak. A calibration curve was constructed using a least squares regression algorithm in the software. A correlation coefficient of 0.9990 was obtained. 

Note Lindane is Y-hexachlorocydohexane, B(a)P is benzo(a)pyrene. The organic carbon-water partition coefficient Kqc only nn estimate and can vary considerably. For organics, it is estimated as 0.35 /fow nnd for metals typical empirical vales are used. 

As shown in Table 6.9, (%p + fewo) is less than %,max for all of the example chemicals. Therefore, the continuous rain assumption is not producing unrealistically high wet deposition rates for these chemicals. The half-times for total wet deposition of the substances are benzene, 1.6xl0 h or about 180 years HCB, 3.7xl0 h or about 40 years Lindane, 431 h or 18 days B(a)P, 134 h or 5.6 days and nickel, 143 h or 6 days. Benzene and HCB are not efficiently removed from the atmosphere by wet deposition. Lindane and B(a)P are removed by wet gaseous deposition, and nickel by wet particle deposition. The 6-day half-life of nickel in the atmosphere represents the half-life for removal of particles by wet deposition in the generic scenario. This value is sensitive to the selected values for the rain rate and the scavenging ratio. The value of the maximum mass transfer coefficient for wet deposition corresponds to a minimum half-life in air of 38 h or 1.6 days. 

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