Soil function tests

Other simple tests include the soil burial test used to demonstrate the biodegradabiUty of polycaprolactone (25), following its disappearance as a function of time, and the clear 2one method which indicates biodegradation by the formation of a clear 2one in an agar medium of the test polymer or plastic as it is consumed (26). The burial test is still used as a confirmatory test method in the real-world environment after quantitative laboratory methods indicate bio degradation. 

In PAH solubilization tests with soil, batch-test soil-aqueous samples with nonionic surfactant and 14C-PAH were rotated on a tube rotator periodically to maintain the soil in suspension during equilibration. The samples were centrifuged, and aliquots were expressed through preconditioned 0.22- xm Teflon filters to reduce soil-derived colloidal substances. The extent of PAH solubilization in nonionic surfactant solution without soil was assessed in batch tests as a function of surfactant dose to confirm the value of PAH aqueous solubility (S) and to determine the values of Scmc and MSR. Nonionic surfactant sorption onto soil was evaluated for sub-CMC (or sub-CAC) aqueous-phase concentrations by surface-tension measurements. Supra-CMC sorption of nonionic surfactant to determine or supra-CAC isotherm was assessed either with azo dye solubilization and spectrophotometric analysis, or by measurement of chemical oxygen demand, from which the amount of surfactant in bulk solution could be inferred (10). 

Kula, C. and Rombke, J. (1998) Evaluation of soil ecotoxicity tests with functional endpoints for the risk assessment of plant protection products - state of the art. Environmental Science and Pollution Research, 5, 55-60. 

Hepatic Effects. Liver effects in humans were not reported in a compilation of cases and personal reports of acute dermal exposure to chlordane (EPA 1980a). Balistreri et al. (1973) reported clinical hepatic effects consisting of jaundice, hepatomegaly and elevated serum transaminases in an infant following "prolonged" dermal exposure to liquid chlordane. Liver biopsy revealed centrilobular necrosis, fatty infiltration, and minimal inflammation. Liver function tests were normal in a 47-year-old nurseryman who handled soil sprayed with chlordane and other chemicals for 2 years (Barnes 1967) there was no estimate of exposure concentration or dose. 

Figure 6.12 Weight loss of corn starch/EVOH films in a soil burial test as a function of time and of amylose content, (a) 70% amylose, (b) 25% amylose (c) 5% amysose [118].

Available Chlorine Test. The chlorine germicidal equivalent concentration test is a practical-type test. It is called a capacity test. Under practical conditions of use, a container of disinfectant might receive many soiled, contaminated instniments or other items to be disinfected. Eventually, the capacity of the disinfectant to serve its function would be overloaded due to reaction with the accumulated organic matter and organisms. The chlorine germicidal equivalent concentration test compares the load of a culture of bacteria that a concentration of a disinfectant will absorb and still kill bacteria, as compared to standard concentrations of sodium hypochlorite tested similarly. In the test, 10 successive additions of the test culture are added to each of 3 concentrations of the hypochlorite. One min after each addition a sample is transferred to the subculture medium and the next addition is made 1.5 min after the previous one. The disinfectant is then evaluated in a manner similar to the phenol coefficient test. For equivalence, the disinfectant must yield the same number of negative tubes as one of the chlorine standards. 

When new pesticides are developed, their effects upon soil communities are tested. Typically these tests use functional parameters (e.g., generation of CO2 or nitrification) (Somerville and Greaves 1987). Many effects shown on soil communities are of short duration and are thought to lie within the range of normal fluctuations in soil processes. 

Application verification (AV) monitors are devices that are placed within test plots to measure actual spray deposition that occurred during application. The main function of AV monitors is to show whether or not the intended amount of test material was actually deposited on the soil surface. Application monitors consisting of soil-filled containers, paper disks, polyurethane foam plugs, and glass Petri dishes have all been used successfully for this purpose. Prior to using a monitor in the field, it is important to determine that the test substance can indeed be successfully extracted from the monitor and that the compound will be stable on the monitor under field conditions... 

The ET cover cannot be tested at every landfill site so it is necessary to extrapolate the results from sites of known performance to specific landfill sites. The factors that affect the hydrologic design of ET covers encompass several scientific disciplines and there are numerous interactions between factors. As a consequence, a comprehensive computer model is needed to evaluate the ET cover for a site.48 The model should effectively incorporate soil, plant, and climate variables, and include their interactions and the resultant effect on hydrology and water balance. An important function of the model is to simulate the variability of performance in response to climate variability and to evaluate cover response to extreme events. Because the expected life of the cover is decades, possibly centuries, the model should be capable of estimating long-term performance. In addition to a complete water balance, the model should be capable of estimating long-term plant biomass production, need for fertilizer, wind and water erosion, and possible loss of primary plant nutrients from the ecosystem. 

FIGURE 26.7 Hydraulic conductivity as a function of PI for soils in Austin Laboratory Tests. (Adapted from U.S. F.PA, Requirements for Hazardous Waste Landfill Design, Construction, and Closure, EPA/625/4-89/022, U.S. Environmental Protection Agency, Cincinnati, OH, August 1989.)... 

The linear equilibrium isotherm adsorption relationship (Eq. 11) requires a constant rate of adsorption, and is most often not physically valid because the ability of clay solid particles to absorb pollutants decreases as the adsorbed amount of pollutant increases, contrary to expectations from the liner model. If the rate of adsorption decreases rapidly as the concentration in the pore fluid increases, the simple Freundlich type model (Eqs. 8 and 9) must be extended to properly portray the adsorption relationship. Few models can faithfully portray the adsorption relationship for multicomponent COM-pollutant systems where some of the components are adsorbed and others are desorbed. It is therefore necessary to perform initial tests with the natural system to choose the adsorption model specific to the problem at hand. From leaching-column experimental data, using field materials (soil solids and COMs solutions), and model calibration, the following general function can be successfully applied [155] ... 

To test this theory, the authors measured water vapor adsorption isotherms for RAMEB-treated soils. The amount of water adsorbed (kg water/kg soil) was monitored as a function of the partial pressure of water (p/po), the dose of RAMEB in the soil (0, 1, or 9%), and the type of soil. Seven soils were studied and arranged in order of increasing clay content (3, 8, 11, 16, 25, 36, and 49% clay content for SI, S2, S3,... S7, respectively). 

A total of thirteen ECs were prepared. Four ECs were used as controls, i.e., no electrical current was applied. One column was designed so that in-situ Eh-pH conditions could be monitored, while the remaining ECs were part of the experiments designed to model the electrosmotic transport of TCE as a function of time. In these experiments, soil columns were subjected to EO for a period of time ranging from one to four weeks. Three columns (two test and one control) were dissected weekly, sampled and TCE concentrations measured. In this way, profiles of TCE concentration were collected as a function of distance from the anode and as a function of time. The TCE and DCE isomers in the Eh-pH column was analyzed at the end of the experiment (672 hr). 

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