Sorption and fate of DNAN and its products in soil
Sorption and fate of the four chemicals were measured individually
in the two sterile soils under aerobic conditions (Fig. 4). The
amounts of chemicals sorbed on soil were obtained by extraction
in CH3CN, which should only desorb chemicals sorbed by weak
(electrostatic, electron donor–acceptor) and stronger (hydrophobic
partitioning) reversible interactions but not the ones irreversibly
chemisorbed by covalent binding (Elovitz and Weber, 1999). While
DNAN sorbed reversibly on the two soils, the monoamines sorbed
both reversibly and irreversibly on both soils, and DAAN sorbed or
reacted (see stability of DAAN below) irreversibly in the two soils
(Fig. 4). Kd values corresponding to reversible non-covalent binding
are provided in Table 3 along with normalized Koc values. The
concurrent reversible and irreversible processes observed with
2-ANAN and 4-ANAN led to non-equilibrium situations that forced
us to measure Kd values for both monoamines at day 2, when
irreversible binding was at its minimum.