Degradation of ¹⁴C‐Atrazine Bound Residues in Brown Soil and Rendzina Fractions

Abstract

The remobilization and the fate of 14C-ring labeled atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) bound residues was examined in relation with the turnover of natural soil organic matter. Soil fractions of a brown soil and a rendzina were incubated under controled laboratory conditions. The mineralization of natural organic matter and atrazine-bound residues was respectively estimated by the amounts of CO2 and 14CO2 evolved during the incubation. The remobilization and distribution of 14C residues among the soil organic fractions were achieved after physical-chemical extractions of the samples. Comparisons of samples in abiotic and biotic conditions allowed us to assess the influence of microbial activity on the fate of atrazine-bound residues. The mineralization curves showed that natural organic matter and atrazine-bound residues had similar decomposition patterns. After 100 d of incubation, 0.8 to 3.6% of total organic C was evolved as CO2, while only 0.1% of the initial radioactivity was mineralized as CO2, and 7 to 15% was becoming extractable with water and methanol. Few differences were observed in the distribution of residues within organic compounds for both fractions of the rendzina, except a decrease of the 14C radioactivity of the 50- to 5000-microm fraction and a slight increase of that of humin. For the 0- to 5000-microm brown soil fraction, increased radioactivity in humin at the expense of humic (HA) and fulvic (FA) acids was detected after incubation, while for the 0- to 50-microm fraction more radioactivity was recovered with FA.

Atrazine bound residues formation and dissipation in subtropical soil under swine wastewater application

“…Treatment T4, in which the soil did not go through the process of sterilization, presented the lowest mean value for extractable residues, indicating that a biological degradation of atrazine occurred. This result corroborates with MUNIER-LAMY et al (2002), who also observed that the presence of the natural soil microbiota led to a decrease in the amount of extractable residues of atrazine after 120 days of incubation. The means followed by the same letter in the column do not differ among themselves at 5% significance by the Scott-Knott Test.…”

Study of atrazine degradation in soil from Kenyan sugarcane-cultivated fields in controlled laboratory conditions

“…DIA and DEA are more toxic than atrazine, while HA is less mobile than atrazine (Munier-Lamy, Feuvier, and Chone 2002). The degradation of atrazine to HA proceeds chemical transformations at low pH in the presence of humic acids.…”