Leaching soil column

Soil Column Leaching. Glass tubing (diameter = 1 cm) was cut into 50 cm lengths, and one end was plugged with glass wool and Miracloth . Air dry soil (percent moisture = 2%, 1%, 4%. for Felton, Keeton, Prairie, respectively) was packed into the tubes to a depth of 30 cm. A small layer of white builders sand was then... 

Soil Column Leaching. The distribution of radioactivity from [ 1 C]butylate applied at 4.5 KG/HA and [1 l C]alachlor and [1 C] — metolachlor applied at 2.25 KG/HA and leached with 15 cm of water in Felton sand, is shown in Figure 4. Although all three herbicides are mobile in this soil type, butylate showed less mobility, with 59.6% of the applied raidoactivity found in the upper 10 cm of the column, while 28.4% and 24.3% of the applied 1 C was found in the upper 10 cm of the alachlor and metolachlor columns, respectively. 

OECD Guideline for the testing of chemicals (2004) Leaching in soil columns, No 312. OECD, Brussels, p 15... 

In leaching field-aged residues of Atrazine and Metolachlor from a soil column, a model with a single diffusion parameter underestimated desorption at early times and overestimated desorption at late times. 

No information concerning the transport and partitioning of 1,2-diphenylhydrazine in the environment was located in the literature. In water, 1,2-diphenylhydrazine is not expected to volatilize because of its rapid oxidation in aerated water (near-surface water) to azobenzene and its low calculated Henry s Law constant (9.42 x 10 atm-m mof) (Lyman et al. 1982). The calculated log Koc (2.76) suggests that 1,2-diphenylhydrazine may sorb to sediments or suspended particles. This is based on the analysis of Kenaga (1980), who stated that chemicals with a K°<= <100 tend to be mobile in soil, while those with a K°<= >L000 tend to sorb. In soil, 1,2-diphenylhydrazine is not expected to leach to groundwater, based on its physical and chemical properties (i.e.. 1,2-diphenylhydrazine reacts rapidly under environmental conditions and, based on its K°c will not rapidly leach downward in the soil column). 

Fig. 12.10 Distribution of napropamide and bromacil in undisturbed soil columns, under continuous (CL) and discontinuous (DL) leaching (White et al. 1986). Square and round symbols denote two different initial soil moisture contents...

Figure 5. Simulated rainfall leaching of tritium from soil column of Sedan ejecta...

Laboratory studies of tritium leaching from Sedan ejecta have shown that a front of almost undiluted soil water is pushed from a soil column when the column is leached with successive aliquots of water. A sample of ejecta was obtained from the maximum tritium zone at 4 feet on Sedan crater lip. This material was placed in four long glass columns, 72 mm. in diameter and 30 cm. long. Separate aliquots of water (equal to 1 inch of rainfall) were poured on the top of the soil columns each day. The column was allowed to drain, and each aliquot of leachate was collected daily and assayed for tritium. Figure 5 shows the elution of tritium from one of the large columns of Sedan ejecta. Each data point in Figure 5 represents the concentration of tritium in the daily collection of leachate. 

Boydston, R.A. (1992). Controlled release starch granule formulations reduce herbicide leaching in soil columns. Weed Technol., 6 317-321. 

Liu, Z., S.A. Clay, D.E. Clay, and S.S. Harper (1995). Ammonia impacts on atrazine leaching through undisturbed soil columns. J. Environ. Qual., 24 1170-1173. 

Reddy, K.N. and M. Singh (1993). Effect of acrylic polymer adjuvants on leaching of bromacil, diuron, norflurazon, and simazine in soil columns. Bull. Environ. Contam. Toxicol., 50 449 457. 

In addition to the effect of pH on mobility, the type of acid entering environmental systems may also be important. Nitric acid was found to leach more aluminum from soil columns representative of high-elevation forest floor soils than did sulfuric acid (James and Riha 1989). This is most likely due to the higher solubility of aluminum nitrate than aluminum sulfate. However, in mineral horizons below the forest floor, the study found that concentrations of aluminum leached by these acids did not differ from concentrations of aluminum leached by distilled, deionized water at a pH of 5.7. The authors concluded... 

Chen, Y.X., Zhu, G.W., Tian, G.M. and Chen, H.L. (2003) Phosphorus and copper leaching from dredged sediment applied on a sandy loam soil column study, Chemosphere 53, 1179-1187. 

OECD (2002). OECD Guidelines for the Testing of Chemicals Revised, Proposal for a New Guideline 312, Leaching in Soil Columns. 

Figure 1. Influence of surfactants on leaching depth of diuron as determined by 50% kill of oats in 2-inch soil columns...

Soil. Degrades in soil by microbial and photolytic process. In the field, in a range of 4 soils, mean DTJ0 c. 25 days mean DT90 c. 169 days. There was minimal movement in soil column leaching studies... 

Soil. Leaching behavior is inversely related to clay and organic matter content of soils. In soil column and soil layer studies, 97% was remaining in the top soil, with 0.1% in leachate... 

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