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.

The percentages of technical aldrin, chlordane, endrin, heptachlor, Dilan, isodrin, BHC, and toxaphene remaining in Congaree sandy loam soil after 14, years were 40, 40, 41, 16, 23, 15, 10, and 45, respectively; those of purified aldrin and technical dieldrin after 15 years were 28 and 31, respectively; and the percentage of technical DDT in three soils after 17 years was 39. Treatments and maintenance of the soils were such that leaching, volatilization, photodecomposition, mechanical removal, and probably biological decomposition were at a minimum. These values may approach an upper limit of persistence of insecticides in soil.

No abstract

The toxic herbicide impurity 2,3,7,8-tetrachlorodibenzo-p-dioxin and its homologs decomposed rapidly in alcohol solution under artificial light and natural sunlight, the rate of decomposition depending upon the degree of chlorination. However, photodecomposition was negligible in aqueous suspensions and on wet or dry soil.