Soil irradiation

Photolytic. When profenofos in an aqueous buffer solution (pH 7.0) was exposed to filtered UV light (X >290 nm) for 24 h at 25 and 50 °C, 29 and 56% decomposed, respectively, to 4-bromo-2-chlorophenol and 4-bromo-2-chlorophenyl ethyl hydrogen phosphate. Both compounds were also identified in soil irradiated with UV light. 

On sandy loam soil first-order rate constants for photolytic decline, k = 4.07 x 10 3 lr1 irradiated in moisture-maintained soil, k = 1.07 x 10-3 h 1 irradiated in air-dried soil, k = 1.52 x 10 3 h 1 in dark control moist soil and no degradation in dark control air-dried sandy loam soil from Madia, CA. t,/2 = 120 h for the first 96 h irradiation over all t,/2(calc) = 200 h from 96-168 h but in dark control system t,/2 = 460 h in moist sandy loam soil irradiated metabolism t,/2 = 650 h in dry sandy loam soils. Rate constants due to photolysis k = 2.55 x 10-3 h, and due to moisture k = 3.0 x 10 3 h in moist sandy loam soil (Graebing Chib 2004)... 

R. Azzam, et al. Internat. Symp. on Isotope and Radiation Techniques in Soil Physics and Irradiation Studies, Aix-en-Provence, Proc., p. 321, (1983). 

The use of nuclear techniques for the detection of buried expls (in mines) has been investigated by the US Army over the past 25 years. The basic approach is the use of a direct beam of highly penetrating radiation to irradiate the soil and the measurement of a reflected, scattered, induced or secondary signal to indicate the presence of a buried mine. A complete historical review and analysis of this work has been prepared by Coleman et al (Ref 18), A brief summary of the highlights of the overall effort is provided here... 

El Beit lOD, Cotton DE, Wheelock V. 1983. Persistence of pesticides in soil leachates Effect of pH, ultraviolet irradiation and temperature. Int J Environ Stud 21 251 -259. 

Treatment of the extract with UV light (4) for 16 hours completely destroyed TCDD in the amended soil. The extract from the unamended soil was not changed by irradiation. Peaks close to the TCDD peak in retention time ( 0.2 min) were not altered. Recovery of ca. 100% was obtained when 5 ppb TCDD was added to the soil. A peak should be discernible at a concentration of 1 ppb as seen on the control core. However, background interference, even in the cleaned up residue, increased tremendously at the very low levels, and confirmation of a peak s identity was very difficult. 

UV irradiation was used as a confirmation technique on any peak suspected of being TCDD ( 0.2 min) no TCDD could be detected at less than 1 ppb. The question then arises, what level of contamination had to be present in the original 2,4,5-T to detect 1 ppb TCDD in soil. 

Texture, organic matter content, oxygen status and pH values of soil in use area(s) Amqlmts and timing of precipitation Temperature and solar irradiance in use area(s) (temperate vs. tropical vs. nordic)... 

The time of year in which a pesticide is applied significantly affects its dissipation rate due to temperature, moisture, and solar-irradiance effects on abiotic and biotic dissipation processes. For example, dissipation rates for agrochemical applications made in the springtime are normally greater than those observed for fall (autumn) applications. Thus, the timing of agrochemical applications made in field soil dissipation studies should closely match those occurring under acmal-use conditions. 

Mid-IR spectroscopy, alongside gravimetric and molecular weight determinations, has also been used to analyse the biodegradation by a thermophilic bacterium (isolated from soil) of an LDPE film [44], The mid-IR studies were undertaken using the ATR sampling technique on control samples, samples that had been UV irradiated, and samples that had been UV irradiated then incubated with bacteria. The study showed that the particular bacterial strain was capable of utilising standard and photo-oxidised polyethylene as the sole carbon source. 

Pseudomonas has been disclosed [233], The method consists of mutating the genes by UV irradiation or other methods and separating the desired protein. A specific amino acid sequence, present in that protein, shows the function for regulating the expression of benzothiophene oxidase gene. The fact that the protein is thought to be useful for both, desulfurization and for purification of sulfur contaminated soil or waste waters indicates a probable destructive pathway. 

The effects of soil depth and moisture on pesticide photolysis were studied. Moist soil at depth of 3, 2.5, 2, 1.5, 1, and 0.5 mm were each dosed at 2.5 pg/g with 14C-niclosamide and photolyzed under a xenon lamp at constant temperature. Samples were removed after 20, 40, 110, and 153 h of continuous irradiation. The decrease in percent of niclosamide and the appearance of degradates were followed by analyzing the soil extracts by HPLC [76],... 

To make sewage sludge compatible with plant life in an environmentally friendly way and also to make it usable as a safe soil conditioner, it is desirable to convert it into living humus by aerobic composting. Irradiation of sludge cake and subsequent composting have revealed the following (see Kawakami et al., 1981) ... 

Mixed oak forest, southern France, experimentally irradiated for 18 years by a, 37Cs source at dose rates between 0.3 and 116 mGy/h, equivalent to a yearly rate between 2.6 and 1016 Gy At 60-100 mGy/h (525-876 Gy yearly), all trees, shrubs, and litter were absent low overall insect density soil deficient in carbon, nitrogen, and water. At 15 mGy/h (131 Gy yearly), woody plants were present, but visibly abnormal 6... 

Exposure of hot particle contaminated soil (sampled 15 km north of the Chernobyl Nuclear Power Plant) to film X, Y and Z of a Differential Autoradiographic Imaging Sandwich. The original film size is 85 x 10 x 10 mm, exposure time was 14 days. Area (a) shows irradiation from a 90Sr dominated hot particle whereas irradiation in area (b) is caused by a 137Cs dominated hot particle. 

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