Soil pesticide residue degradation and soil sample management procedures for environmental forensics

The overall goal of this project was to examine soil sampling procedures of each state regulatory agency that regulates pesticide use in that state, and to offer a standardized soil sampling protocol. A survey of each SLA was conducted to determine the types of containers that are typically used when collecting soil samples for pesticide residue analysis and, on average, how long it takes for the soil samples to reach the laboratory once the soil sample is pulled from the field by the investigator. The survey revealed that most states use different protocols when sampling soil for forensics purposes. A research soil pesticide residue sampling protocol was developed to simulate real-world pesticide investigative procedures. A laboratory analysis was then performed on the soil that had been treated with either fipronil or permethrin insecticides and placed in two types of storage containers, opaque bags that block ultraviolet light; and clear glass jars that do not. Soil samples were then placed in a commercial freezer; a cooler with commercial ice; and a growth chamber (incubator) that exposed the soil samples to heat, humidity, and ultraviolet light. The results of the experiment revealed that within seventy-two (72) hours, exposure of the soil samples to freezing, 51.6 Kj/m2 of ultraviolet light, 75% humidity, 100 degrees Fahrenheit, or commercial ice in a cooler, had no statistically significant effect on the level of permethrin residue in the soil samples with the soil properties used in the experiment and a soil pH of 6.2. However, when the pH of the soil was raised to 8.96, all soil samples in the various storage environments revealed significantly less permethrin than the control soil samples except those samples that were immediately placed in a freezer and frozen. The fipronil soil samples in the clear glass jars revealed reduced residue levels due to exposure to ultraviolet light in the incubator