The Chemistry and Phytotoxicity of Arsenic in Soils: II. Effects of Time and Phosphorus
1973
Woolson, E. A. | Axley, J. H. | Kearney, P. C.
Arsenate from sodium arsenate changes to less soluble compounds in soils with time. To study these changes, the arsenic soluble in 1N NH₄Cl, 0.5N NH₄F, 0.1N NaOH, and 0.5N H₂SO₄ solutions was determined. These dissolved arsenates were designated as WS-As (water soluble), Al-As, Fe-As, or Ca-As, respectively. The percent of WS-As present was proportional to As added and inversely proportional to time, and to the Fe and Al content. Fe-As was the predominant form of As in Hagerstown silty clay loam while Al-As predominated in Lakeland loamy sand. Growth of corn (Zea mays) increased with increase in time of As incubation in the soil before planting. Arsenic phytotoxicity and As in the plant were altered by P additions. Arsenic residues in the Lakeland soil became more phytotoxic, while residues in the Hagerstown soil became less phytotoxic with P additions. This plant response was related to the availability of As and P in these soils. Leaching with 0.05M KH₂PO₄ removed 77% of the total As from a contaminated Dunkirk fine sand. The distribution of the forms of As in this soil changed during leaching.
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