(4) Guiliani, A. J. “Methane Recovery From a Shallow Landfill: Experience a t the Fresh Kills, Staten Island, N.Y.”; Symposium Proceedings, Methane from Landfills: Hazards and Opportunities, Denver, CO, March 21-23, 1979. (5) Lu, A. H.; Kunz, C. “Tranducer Measurement of Landfill Gas Pressure”; Symposium Proceedings, Methane from Landfills: Hazards and Opportunities, Denver, CO, March 21-23,1979.
(6) Kunz, C.; Lu, A. H., “Flux-Box Measurement of Methane Ema-
nation from Landfills”; Symposium Proceedings, Methane from Landfills: Hazards and Opportunities,Denver, CO, March 21-23, 1979. Received for review December 17,1979. Accepted December I , 2980. This project has been partially funded by the New York State Energy Research and Development Authorzty.
Runoff Losses of Atrazine and Terbutryn from Unlimed and Limed Soil John D. Gaynor”? and V. V. Volk Department of Soil Science, Oregon State University, Corvallis, Oregon 97331
Atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)s -triazine) and terbutryn (2-( tert -butylamine) -4-(ethylamino)-6-(methylthio)-s -triazine) leaching and loss by surface runoff waters and sediment were measured under simulated rainfall conditions from unlimed and limed Peavine silt loam soil. Application of 7 cm of water produced 2-14% runoff water from the unlimed soil and little (1-3%) or no runoff from the limed soil. Sediment losses were low, averaging 16 kg/ha. Terbutryn was adsorbed by the soil (98%)to a greater extent than atrazine (60%);hence, the eroded sediments contained higher concentrations of terbutryn than atrazine. The amount of terbutryn and atrazine in the runoff water and sediment from simulated sample applied 12 h after herbicide application was only 0.3 and 3.7%, respectively, of that applied. Of that amount, soil transport accounted for 1-3% of the s-triazine in the runoff. Recoveries of atrazine and terbutryn were similar on unlimed and limed soil except for atrazine on unlimed soil. Atrazine recovered after 12 days was 25 and 74% of that applied to the unlimed and limed soil, respectively.
Introduction The s -triazine herbicides applied directly to soil or foliage for broadleaf weed and annual grass control constitute one of the most widely used families of herbicides. With their use under many different soil conditions, s-triazine may move to adjacent fields and waterways by surface runoff and by leaching to ground water. Many environmental and edaphic factors in addition to the chemical and physical properties of the herbicides interrelate to affect runoff losses (1-4). Atrazine loss after a normal and an intensive simulated rainfall averaged 4 and 17%,respectively, while delaying rainfall for 96 h after atrazine application reduced runoff losses 50% (5). Under natural rainfall conditions, annual losses of atrazine by surface runoff and sediment transport averaged 2.6% (6). Most of the loss occurred during the first month after herbicide application, with losses in the aqueous phase of runoff exceeding those associated with the sediment phase. When rainfall occurred closer to application date, 5% of the added atrazine was lost in surface runoff but only 0.02-0.03% of a methoxy-s-triazine ( N -ethyl - 6 -methoxy-N-(1- methylpropyl)- 1,3,5-triazine-2,4diamine) was lost (7). In another study, more prometryn (2,4-bis(isopropylamino) -6-(methylthio)-s -triazine) was lost from moist soil than dry soil presumably because of decreased adsorption sites, but rainfall intensity did not affect losses (8).
+ Present address: Res. Stn., Agriculture Canada, Harrow, Ontario NOR 1G0, Canada. 440
Environmental Science & Technology
Similarly, leaching of s -triazine herbicides is related to solubility, formulation and application rate, adsorption, soil moisture content, and infiltration rate of the soil. s-Triazine mobility increases with a decrease in the clay fraction in soils (9),but high adsorption and low solubility of the s-triazine herbicides generally prevents leaching to depths greater than 15 cm (9,10).Leaching in fine textured soils to depths greater than the plow layer has been observed when rainfall averaged 70 cm and high rates (>4 kg/ha) of simazine (2-chloro-4,6bis(ethy1amino)-s-triazine) or atrazine were applied (9). Leaching up to 20 cm has been reported in coarse textured soils a t application rates of
