Agronomy pit

Figure 2. Cross-section of canopied 13.7 x 7.3 m plastic-lined Agronomy pit with a distribution system (solid bar) embedded in rock (cross-hatched) and five sampling tiles extending through the rock and soil (slanted lines).

Agronomy Pit. Liquid samples only were collected from five access tiles at the Agronomy pit. These were analyzed individually and as a composite, with results agreeing within 2%. 

No soil samples were taken from within the Agronomy pit. One set of soil samples to a depth of 3 m was taken from 10 cm diameter holes augered at each outside corner of the pit. Water samples from outside the pit were also collected from the seepage of ground water into the augered holes and from other sites remote from the pit location. Air samples for pesticide vapor analyses were collected in the vicinity of the pit. 

Liquid Samples. Three procedures were evaluated for extracting pesticides from liquid samples collected at the Horticulture and Agronomy pits. They were the resin sorption method of Junk et al. (2), solvent extraction with hexane-diethylether, and solvent... 

Table I. Concentration Difference in Liquid Samples from Agronomy Pit when Settling, Centrifuging and Filtration are Employed...

Similar segregation was observed in liquid samples collected from the Agronomy pit where a system was installed to uniformly distribute the pesticides. Concentrations of pesticides varied by a factor as high as 10 in the June 1978 liquid samples as shown in Table V. 

Table V. Herbicide Concentrations at the Five Sampling Points in the Agronomy Pit - June 1978...

The accumulations of the amounts of pesticides deposited in the Agronomy pit are given in Table IX. This pit was constructed in... 

Table IX. Disposal Accumulations at the Agronomy Pit in Grams of Active Ingredient (Al)...

The Agronomy pit is also an uncontrolled disposal system so the analytical data are perturbed by the same variables of amount, timing, degradation and losses as described in the discussion of the Horticulture pit. 

Liquid Analyses. The pesticide residues in the liquid samples taken from the Agronomy pit are given in the graphical plots in Figure 4 where the amounts present at each sampling date are plotted separately for each pesticide. The vertical axes are either 0-15, 0-150 or 0-1500 Ug/g of liquid sample depending on the maximum concentration observed for any one residue in the liquid phase. The pesticide plots are ordered alphabetically for ease of location. The formulations are shown immediately below the common names on the plots. 

Extracts of samples from the Agronomy pit were also analyzed for chlorambem, glyphosate, malathion, metolachlor and perflura-lin. They were either not detected or, if detected, concentrations were <1 ppm. Plots are not included for several pesticides where only results from 1979 were available. These pesticides, with their average ppm concentrations in parentheses, were bentazon (150), 2,4-D (30), dicamba (10), paraquat (20) and 2,4,5-T (40). 

Figure 4. Plots of the pesticide concentrations in liquid samples taken from the Agronomy pit during 1978-1979.

Soil samples taken at the corners of the Agronomy pit were composited and portions were analyzed for pesticide residues. No pesticides were found at the detection limit of 10 Pg/g soil. 

Surrounding Air Analyses. The results of the analyses of the air taken above the Agronomy pit are given in Table XI for June 28, August 14 and August 24, 1979. The interpretation of these re-... 

Surroundings Summary - Agronomy. From interpretation of the above results for soil, water and air surrounding the Agronomy pit, little contamination can be attributed to its operation. 

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