EFFECT OF CONCENTRATION AND ENVIRONMENTAL FORM OF TETRADECENYL SUCCINIC ACID ON ITS MINERALIZATION IN SOIL

Tetradecenyl succinic acid (TSA) is the major component of a detergent builder (C12-C14 alkenyl succinic acid), which is inherently biodegra dable. C-14-TSA was dosed as a component of sewage sludge into a soil with a history of sludge amendment at final added concentrations of 1. 5 and 30 mg (kg soil)(-1) In addition, it was dosed to the soil in an aqueous solution to a final added concentration of 30 mg (kg soil)(-1) . Dose and form were found to have a pronounced effect on the minerali zation kinetics. When dosed in a realistic form and concentration (i.e . 1.5 mg (kg soil)(-1) as a component of sludge), TSA was mineralized at its highest rate and to its greatest extent, and the mineralization half-life was 2.4 days. When dosed at 30 mg (kg soil)(-1) as a compon ent of sludge, mineralization began immediately, and the half-life was 23 days. In contrast, when dosed al this concentration in aqueous sol ution, the onset of mineralization was preceded by a 13 day lag period and the mineralization half-life was 69 days. Primary biodegradation and mineralization rates of TSA were very similar. Approximately, half the radioactivity was evolved as (CO2)-C-14, while the remaining radi oactivity became non-extractable, having presumably been incorporated into biomass or natural soil organic matter (humics). This study demon strated that TSA is effectively removed from sludge-amended soils as a result of biodegradation. Furthermore, it showed the effect that dose form and concentration have on the biodegradation kinetics and the im portance of dosing a chemical not only at a relevant concentration but also in the environmental form in which it enters the soil environmen t.