I.~Rates of reaction and product analysis of sulfur containing compounds in reaction with potassium ferrate. II.~Monitoring of sub-part-per-billion levels of atrazine as a determinate of subsurface water motion under induced recharge

I. The kinetics of the oxidation of dimethyl sulfide by ferrate was extended to the range of pH = 10.0 to 7.5. Product analysis by GC/MS shows a predominance of dimethyl sulfoxide in reactions taking 30 minutes to complete and dimethyl sulfone in reactions taking 30 seconds to complete. Experiments using 50% H$\sb2\sp{18}$O as solvent were performed to allow identification of the oxygen in products. The kinetics of oxidation of 2,2$\sp\prime$-thiodiethanol was studied over the pH range 6.5 to 8.5 and thiodiglycolic acid from 6.00 to 9.00. Kinetic data were obtained for diethyl sulfide at pH = 7.5 and 7.0 and for sulfonyldiethanol at pH = 7.0. Comparison of rates of oxidation of these compounds shows a rate dependance on the oxidative state of the sulfur. Compounds that have an unoxidized sulfur react much faster than those with fully oxidized sulfur. Oxidative state of the terminal carbon was only a minor factor in the rate of the oxidation. II. Atrazine is a triazine based herbicide used in broadleaf weed control in the cultivation of corn and sorghum. Run off from treated fields in the drainage basin of the Platte River carries a significant amount of atrazine into the river. A method was developed to detect atrazine at 0.05 part per billion detection limit with a sample volume of 10 milliliters. The herbicide is extracted from 10 mL water using C-18 solid phase extraction and analyzed by GC/MS. Terbuthylazine is used as internal standard to compensate for extraction process variables. Standard curves have consistently shown correlation coefficients of 0.99 or better. Duplicate samples show a variance of 5% or less. Using this technique atrazine can be seen to progress through a series of sample wells from the river inland toward and beyond a production well under the impetus of induced recharge