Determination of the rate of tripoly and pyro-phosphate hydrolysis in sediments

Students supported: 1 Ph.D., 4 UndergraduatesThe rate of hydrolysis of tripolyphosphate (TPP) and pyrophosphate (PP) in sediments was determined. The sediments used were collected from Cape Fair, Thomas Hill Lake, Flat Branch Creek, and Maries River. The rate of hydrolysis of TPP and PP was similar to that predicted from first order kinetics. Half lives for the hydrolysis of TPP and PP were found to be 1.6 to 2.6 and 6.7 to 27.4 days, respectively. The influence of temperature, biological activity, and pH on the rate of TPP and PP hydrolysis was investigated using Flat Branch Creek sediment. The rate of TPP and PP hydrolysis increased with increasing temperature. The activation energy was 5415 cal/mole for TPP and 10,412 cal/mole for PP. TPP and PP were hydrolyzed faster in non-sterile sediment than in sediment which had been sterilized, possibly due to the destruction of phosphatase and pyrophosphatase enzyme systems during sterilization. The half life for TPP hydrolysis was 1.76 day at pH 5, 1.61 day at pH 7, and 2.16 day at pH 9. PP hydrolysis was increased as pH was increased from 5 to 7 to 9 as indicated by half lives of 13.7, 10.0, and 7.3 days, respectively. When TPP was added to the sediment as a Ca5(P3O10)2 precipitate the rate of hydrolysis was slower (1/2life= 2.79 day) than when TPP was added as a solution (1/2life = 1.68 day).Project # A-059-MO Agreement # 14-01-0001-382

Distribution and chemistry of phosphorous in an albaqualf soil after 82 years of phosphate fertilization

The distribution of phosphorus in a fertilized and unfertilized Mexico silt loam soil was measured. After 82 years of phosphorus fertilization the added phosphorus was found in Ap (0-23 cm), smaller amounts in the A and B, and B2 (23-86 cm), and large amounts in the B3 and upper C (86-137 cm) horizons. No added phosphorus was found below 137 cm. The distribution of added phosphorus was similiar to that of the original phosphorus in the soil profile. The phosphorus adsorption capacities of fertilized and unfertilized soils were similar. These data indicated that 82 years of phosphorus fertilization nearly doubled total phosphorus content in the soil but did not change the ability of the soil to adsorb additional phosphorus. Ion products indicated that the phosphorus level in the soil solution was controlled by the solubility of strengite. Apparently those: factors which influence the solubility of strengite will influence the movement of phosphorus in the Mexico silt loam, soil.Project # A-031-M

Prediction of water soluble arsenic in sewage-soil systems

Missouri orchard soils were analyzed for total As, Pb, and Cu content. All Cu concentrations were normal, while Pb and As concentrations varied from natural levels to over 2000 ppm for Pb and 350 ppm for As. The Bray tests for available phosphorus were high by 0-8 to 16.8 percent due to arsenic interference on soils from arsenic contaminated fields. Fifteen g samples of a Sharpsburg silty clay loam and a Menfro silt loam soil containing 320 and 160 g As/g, respectively, were equilibrated for 21 days with 30 ml of distilled water or 1 percent dextrose. After 21 days the samples were freeze dried, divided into 2 groups, one air dry and the other at 26.7 percent water and exposed to the atmosphere. Eh, pH, As, Fe, Al, Mn, Ca and Pb in solution were determined periodically. After an initial Eh drop in the 1 percent dextrose equilibration, the As in solution increased rapidly in both soils, but was constant after 12 days.Project # A-068-MO Agreement # 14-03-0001-4025 and 502

Effect of subsurface structure and bypass water flow on copper and zinc movement

The potential movement of heavy metals beyond the soil application zone is a cause for public concern. Structural features of the argillic horizon in soils such as the Tuskeego (fine mesic montomorillonitic, mesic Mollie Ochraqualfs) would allow flow along the surface of the peds and allow metals to move through the profile as "bypass" flow. Experimental plots, which had received large amounts of Cu and Zn with 96 ton/acre sewage sludge application, were sampled 10 years after the applications and analyzed for Cu, Zn, and P. Core samples from Ap, BE, Btg1, and Btg2 horizons of control and sludge treated plots. Pits were dug so that samples of the vertical, horizontal, and internal structure surfaces of the Btg1 and Btg2 horizons samples could be carefully removed with a knife. Samples were digested with nitric/percohloric acids and Cu, Zn, and P determined. Soil P, Cu, and Zn levels significantly increased in the Ap and BE horizons (above 30 cm at the average) due to the sludge addition. Sludge addition did not significantly increase Cu or P concentrations along vertical or horizontal ped faces or in the ped interiors of Btg1 or Btg2 horizons. Sludge addition significantly (0.05) increased Zn concentrations in the Btg1 and Btg2 horizons. The trend for sludge addition to increase Zn concentration on ped faces more than ped interiors was not significant. There is no evidence to indicate that Cu or P moved downward. Elevated Zn concentrations in Bt horizons could be attributed to many factors including deposition with root residue or bypass flow.Project # G-2029-02 Agreement # 14-08-0001-G-2029-0