Strength from soil

Goldberg S., Forster H.S., Heick E.L. Boron adsorption mechanisms on oxides, clay minerals and soils inferred from ionic strength effects. Soil Sci Soc Am J 1993 57 704-708. 

Sabljic, A. (1984) Predictions of the nature and strength of soil sorption of organic pollutants from molecular topology. J. Agric. Food Chem. 32, 243-246. 

Soils exhibit a large variety of characteristics that are used to classify them for various purposes, including crop production, road construction, and waste disposal. The parent rocks from which soils are formed obviously play a strong role in determining the composition of soils. Other soil characteristics include strength, workability, soil particle size, permeability, and degree of maturity. 

Aeetie acid is produced photoehemieally mainly from reactions of the peroxy acetyl radical (CH3CO3) wifli oflier peroxy radieals. For example, the reaction of CH3CO3 with HO2 is known to lead to about 20% CH3C(0)OH (Tyndall et al, 2001). Aeetie acid in the gas phase is also produced by reaction of ozone with various olefins like propene, butene or pentene (Atkinson and Arey, 2003). A total photochemical source strength of 120 Tg/year has been reported (Baboukas et al, 2000). The contribution of direct emissions from anthropogenie (biomass eombustion, motor exhaust) and biogenie (bacteria metabolisms, emission from soil and vegetation) sourees is estimated at 48 Tg/year (Chebbi and Carlier, 1996). 

For less soluble contaminants like PAHs and PCBs, it is not possible to measure pore water concentrations. Chemical availability has to be measured with a method that extracts a certain part from soil. Methods are available, such as a mild extraction for a short period of time. Relation with effects have been empirically established (certain strength and certain time). Methods are easy and cheap, but valid only after establishing the empirical relationship. Other methods are based on a strong adsorbent and stimulate the diffusion from the solid phase into the water phase and on to the adsorbent. This process is easier to understand (based on equilibrium between soil and water), but is also based on empirical relationships (Reid etal. 2000). 

LLE is a widely used technique among the official US-EPA methods for the preconcentration of pesticides in liquid samples. Nonpolar solvents for the LLE of pesticides include w-hexane, benzene, and ethyl acetate. Water-miscible solvents for this purpose include dichloromethane, methanol, acetonitrile, acetone, and water, which have been employed for the extraction of residues from high-moisture commodities. Mixed solvents have often been used to finely adjust the solvent strength. Thus, various carbamate pesticides were extracted from aqueous environmental samples with chloroform and determined by HPLC with a mean recovery of 71 Also, a method based on the extraction by sonication of solid samples placed in small columns with a low volume of ethyl acetate was developed for the extraction of thiocarbamates and other herbicides from soil with recoveries between 89 and 109%. ... 

The conditional stability constants (log K<.) obtained for copper with humic compounds extracted from soils and natural waters are invariably greater than those for other transition metals (see Table IV). This is expected from the enhanced levels of crystal field stabilisation energy which result fi-om the splitting of the 3d electronic orbitals on Cu by an octahedral field (Mackay and Mackay, 1969). The divei ence in the values of log Kc shown in Table IV, may, in part, have arisen from intrinsic variations in the copper-binding properties of the various humic samples. However, these deviations may also be explained in terms of the different experimental conditions employed (pH, ionic strength, temperature, for example) and the assumptions made in the calculations. For example, an increase in the pH will enhance the availability of dissociated binding sites (see Section 6) which are then free to participate in further complexation of copper and... 

Although the estimated source strengths remain uncertain, emissions from soils appear to dominate the nitrons oxide bndget (IPCC, 1990). The main biogenic sources of nitrous oxide, NO, and N2 in soils are the microbial processes of denitrification and nitrification. 

LaRC 03 failure criterion The LaRC 03 failure criterion [12] consists of a family of six criteria. It is an extension of the Puck [11] and Hashin [13] failure criteria. Like the Puck criterion, it focuses on the fiacture plane that is determined by maximizing the Mohr—Coulomb stresses. In the LaRC 03 criterion, failure due to matrix compression is the result of local interaction of shear stresses on a fracture plane. This perspective comes from soil mechanics situafions where the compression strength is different than the tension strength. It is parficularly useful in cases where, on a certain plane in the material, there are both normal and shear stresses acting. The interaction line that... 

General methodologies for correcting laboratory triaxial and simple shear test results to in-situ strengths. (From Chaney, R.C. et al.. Toward a unified approach to soil property characterization In situ versus laboratory. In Strength Testing of Marine Sediments Laboratory and In-Situ Measurements, ASTM STP 883, Chaney, R.C., and Demars, K.R., eds., American Society for Testing and Materials, Philadelphia, PA, 425-439,1985. Reprinted with permission from ASTM.)... 

Determination of SRD There are two primary methods available to determine SRD. These methods are (1) CPT method (de Ruiter and Beringen, 1979), and (2) utilization of soil strength data from soil investigations (Toolan and Fox, 1977). 

In the second method, soil strength data from soil investigations are used to compute the SRD. In this procedure, remolded friction values are used directly in sands and clays, while for pile tip resistances the undisturbed values are used (Toolan and Fox, 1977). 

The vane technique has its origins as a method for in situ measurements of the shear strength of soils and an important assumption in the method is that the yielding surface that results from the vane s rotation is cylindrical, and of the same diameter as the vane (corrections can be made at a later stage if this is proven otherwise but they are difficult to assess for opaque materials). This assumption dictates that the material between the blades acts as a solid cylinder of dimensions equal to those of the vane, and the issue of the yield smface of visco-elastic and plastic fluids in a vane-viscometer has been addressed in several studies (e.g. see Yan and James, 1997 Keentok et al., 1985). 

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