Sediment-water partition coefficient

DNAPLs have higher densities than water, most between 1 and 2 g/mL, some are near 3 g/mL, for example, bromoform, which has a density of 2.89 g/mL. They have limited water solubilities, and are usually found as the free-phase immiscible with water or as residuals trapped by soil. Most DNAPLs are volatile or semivolatile Pankow82 has listed information on their physical and chemical properties, such as molecular weight, density, boiling points, solubility in water, vapor pressure, sediment/water partition coefficient, viscosity, Henry s law constant, and so on (see Tables 18.8 and 18.9). 

The Level I calculation suggests that if 100,000 kg (100 tonnes) of benzene are introduced into the 100,000 km2 environment, 99% will partition into air at a concentration of 9.9 x 10-7 g/m3 or about 1 pg/rn3. The water will contain nearly 1% at a low concentration of 4 pg/rn3 or equivalently 4 ng/L. Soils would contain 5 x 10-6 pg/g and sediments about 9.7 x 10 6 pg/g. These values would normally be undetectable as a result of the very low tendency of benzene to sorb to organic matter in these media. The fugacity is calculated to be 3.14 x 10-5 Pa. The dimensionless soil-water and sediment-water partition coefficients or ratios of Z values are 2.6 and 5.3 as a result of a Koc of about 55 and a few percent organic carbon in these media. There is little evidence of bioconcentration with a very low fish concentration of 3.0 x FT5 pg/g. The pie chart in Figure 1.7.6 clearly shows that air is the primary medium of accumulation. 

Vowles, P.D., Mantoura, R.F.C. (1987) Sediment-water partition coefficients and HPLC retention factors of aromatic hydrocarbons. Chemosphere 16, 109-116. 

Gschwend, P.M. and S. Wu. 1985. On the constancy of sediment-water partition coefficients of hydrophobic organic pollutants. Environ. Sci. Technol. 22 1435-1440. 

Cadmium in the Greifensee Lake (Stumm and Morgan, 1981). This Swiss lake has a volume V of 1.25 x 108 m3, water input is (2 = 9 x 107 m3 a"1, sedimentation rate is P=4x 107kga 1. Cd has a sediment-water partition coefficient DCd = 65m3kg1. Calculate the Cd residence time in the lake. 

Vowles and Mantoura [38] determined sediment-water partition coefficients and the high-performance liquid chromatography capacity factors for 14 alkylbenzene and polyaromatic hydrocarbons. The partition coefficients correlated well with the alkyl-cyano capacity factors, and it was concluded that this phase gave a better indication of sorption on sediment than either the octanol or octadecylsilane phases. 

PBDEs adsorb strongly onto suspended solids and sediments in the water column. Volatilization of PBDEs from water surfaces will be attenuated by adsorption, and thus is notan important fate process. Sediment-water partition coefficients (K,) have been measured for several components of commercial... 

Steady-state modeling calculations were performed to examine how congener-specific properties (such as sediment-water partition coefficients, Henry s law constants, and molecular diffusion rates) affect the transport and fate of PCBs. A basic description of the model, along with modeling results, is presented here to further explain the importance of physiochemical weathering processes in controlling the fate and distribution of PCB congeners in Twelve Mile Creek and the upper portion of Lake Hartwell. 

Vowles, P. D., and R. F. C. Mantoura, Sediment-Water Partition Coefficient and HPLC Retention Factors of Aromatic Hydrocarbons. Chemosphere, 1987 16, 109-116. 

Baker, J.E., P.D. Capel, and S.J. Eisenreich. 1986. Influence of colloids on sediment-water partition coefficients of polychlorobiphenyl congeners in natural waters. Environ. Sci. Technol. 20, 1136-1143. 

Karickhoff, S. W., and Brown, D. S. (1979). Determination of octanol/water distribution coefficients, water solubilities, and sediment/water partition coefficients for hydrophobic organic pollutants. EPA/600/4-79/032 (Order No. PB80-103591). 

Chain length ow Kp (sediment-water partition coefficient) Koc (Kp normalized to organic content) Inhibition of a function or process such as photosynthesis, respiration, or bio-luminescence, EC50... 

Karickhoff, S.W. Brown, D.S. "Determination of Octanol-Water-Distribution Coefficients, Water Solubilities, and Sediment-Water-Partition Coefficients for Hydrophobic... 

Table 2-6 Estimated Range of Sediment/Water Partition Coefficients for Various Pesticide Classes (after Pavlou Dexter, 1980)...

It is also assumed that hydrophobic organic chemicals partition only into the organic matter in soils, sediment, and suspended sediment. Further, the organic matter in soils and sediment is not as well represented by octanol as is the lipids in biota. Empirically it has been found that the organic carbon (in soils and sediment)-water partition coefficient, Kocy/ u defined as... 

Returning to our initial example of DDT, based on DDT s extremely large sediment-water partition coefficient, this model suggests that DDT is strongly sorbed to the nonreactive sink (k2 > > k.2) and that transport to reactive sites on the... 

For the determination of sediment PNECs similar assessment factors are used and in addition, if no data are available, it is possible to calculate a provisional sediment PNEC based on an equilibrium partitioning method. This method uses the PNEC calculated for water for aquatic organisms as described above and the sediment/ water partitioning coefficient (TGD, 1996). This method assumes that ... 

The suspended sediment/water partition coefficients have been measured for 19 chlorinated organics in 25 samples from the St. Clair, Detroit and Niagara Rivers. An excellent linear correlation (r = 0.87) between the organic-carbon corrected partition coefficient (Kqq) and the octanol/water partition coefficient (Kq, ) was found (log = 0.76 log + 1.66). Using this equation plus another equation developed in this paper it is shown that the percentage of chemical in the dissolved and particulate phases in the study rivers could be estimated from a chemical s to within a factor of two. The paper also discusses the time required for equilibrium to be achieved between the dissolved and particulate phases, and the potential importance of biota such as algae in the partitioning process. 

Partitioning, suspended sediment/water partition coefficient, Kp, organic-carbon corrected partition coefficient, Kq(, octanol/water partition coefficient, chlorinated hydrocarbons, Kq /Kq, correlations, St. Clair River, Detroit River, Niagara River. 

The sediment/water partition coefficient has been shown to be positively correlated with a chemical s octanol/water partition coefficient, (Kari-ckhoff 1981). Similar relationships have been shown between Kq and a chemical s water solubility, the lower the chemical s solubility the higher (Chiou et al. 1983 Karickhoff 1981). Since Kqw and water solubility are strongly interrelated, they cannot be considered to be completely independent variables. 

Koc,t (sediment organic carbon-water partition coefficient for water concentration with free and bound PAH) = ([Sediment]//oc)/[Watertotai] iTow (octanol-water partition coefficient) = [Octanol]/[Water] (sediment-water partition coefficient) = [Sediment]/[Water]... 

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