Soil release testing

Two bioassays are employed to evaluate the effect of samples on terrestrial life forms. For gas samples, the plant stress ethylene test is presently recommended. This test is based on the well-known plant response to environmental stress release of elevated levels of ethylene (under normal conditions plants produce low levels of ethylene). The test is designed to expose plants to various levels of gaseous effluents under controlled conditions. The ethylene released during a set time period is then measured by gas chromatography to determine toxicity of the effluent. For liquid and solid samples, a soil microcosm test is employed. The sample is introduced on the surface of a 5 cm diameter by 5 cm deep plug of soil obtained from a representative ecosystem. Evolution of carbon dioxide, transport of calcium, and dissolved oxygen content of the leachate are the primary quantifying parameters. 

The procedure given in AATCC Test Method 79 can also be used to determine the degree of absorbency of fabrics finished with soil-release agents. Typically, near instantaneous wetting of the fabric with water (< 1 s) is expected from nonfluorine-containing soil-release finishes. 

AATCC Test Method 130 Soil release oily soil method, AATCC Technical Manual, American Association of Textile Chemists and Colorists, Research Triangle Park, NC, 1999, 217-219. 

The following sections will discuss some of the more important test methods in use for fabrics with durable press, flame-retardant, soil release, repellent, UV protective, antimicrobial, anti-insect, anti-felting, hand building and weighting finishes. 

The fabrics used in this study were prepared by the Southern Regional Lab especially for the 13 states involved in the S-163 Project. They Include 100% cotton, 100% polyester, and a 50/50 cotton/polyester blend. Fabrics are print cloth, woven construction, with a thread count of 70W x 78F, 3.5 ounce per square yard. All fabrics were wet finished and heat set. A durable press finish (DMDHEU) was applied to cotton and cotton/polyester fabrics. A water repellent fluorocarbon finish (Corpel) and an acrylic acid soil-release finish were applied to all three types of fabrics. Our preliminary findings for the AATCC spray test are reported here. 

Soil types tested for Pb species All Pb released to soils— PbS04, PbCOa, PbS, PbCIBr, etc.—is connected to adsorbed complexed forms binding sites are clays, organic acids, hydrous iron oxide Various binding systems Chaney et al. (1988)... 

The water-soluble PEK acts as an excipient, whereas the hydrophobic and water-insoluble PCL acts as a barrier, keeping the device dimensions intact during the release period. Poly(vinyl acetate) (PVAC) reportedly undergoes biodegradation more slowly. Copol miers of ethylene and vinyl acetate are susceptible to slow degradation in soil-burial tests. 

Soil toxicity tests on polymer fragments to ensure that any degradation products released from the plastic have no long-term deleterious effects on plants or on animals that may imbibe them. 

Recently, ecotoxic tests performed on several materials showed that biomaterials (starch, cellulose, polylactic acid, etc.) in soil conditions had a toxic effect at the beginning of the process, and became non toxic after 60 days. On the contrary, polyethylene materials with pro oxidant additives showed a toxic response after 60 days (Fritz, 2004). Similarly, inhibition effects occur during Sturm tests with this material. One explanation could be the release in the environment of poisonous substances contained in the pro-oxidant additive (di thio carbamates) or in other unknown additives. These harmful substanees accumulate in soils. For the above reasons and for agricultural requirements (no accumulation of toxic substances in soils), ecotoxic tests should be performed after a lag phase of three or six months. 

The effects that changes in vegetation have on soil carbon pools and nutrient availability are also difficult to evaluate. However, several models have been successful in predicting vegetation-soil nutrient relationships because they assume that such changes occur as a result of different rates of decomposition and nutrient release from leaf litter of different taxa 50, 60), Such predictions could be tested and the models refined or parameterized for new taxa by measuring soil nutrient availability and respiration in stands of different species on the same soil type. For example, fifty years ago the U.S. Civilian Conservation Corps (CCC) established such stands as species trial plots measurements in some indicate large differences in soil nutrient availability (48), Further measurements in these stands would now occur at the same time-scale at which we expect the feedback between species replacement and soil processes to occur. 

Methyl parathion may also be released to soils by improper handling of pesticide formulations during processing or handling. In a sampling of soils collected from processing facilities in Illinois, methyl parathion was detected in soil at 2 of the 49 sites tested (Krapac et al. 1995). 

Various bioassay methods have been used to detect the "natural" release of allelopathic agents. Sane authors preferred, after partial purification, to assay the extracts by petri dish methods for gemination, growth of roots or shoots and other symptoms of seedlings. The bioassays also included tests in soil or sand and also in nutrient solution (Table 3). 

Radon dissolves into groundwater from rocks or soils. When the water is exposed to the atmosphere, some of the dissolved radon is released. As a rule of thumb, there is an increase of about 1 pCi/L in the air inside a house for every 10,000 pCi/L of radon in the household water.50 Higher radon levels have been observed in individual rooms when water is heated or agitated, such as during shower use.51 Builders should be aware that houses require groundwater as the house water supply could have a radon problem. The only way to be certain that the groundwater is not a potential radon source is to have the water from the well tested. Some states and private companies provide test kits for this purpose. It should also be noted that radon concentrations in water, like radon concentrations in the air, can vary significantly. 

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