Premium
Transformation and binding of 13 C and 14 C‐labelled atrazine in relation to straw decomposition in soil
Author(s) -
Benoit P.,
Preston C. M.
Publication year - 2000
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1046/j.1365-2389.2000.00288.x
Subject(s) - atrazine , chemistry , straw , incubation , organic matter , loam , mineralization (soil science) , decomposition , crop residue , soil water , pesticide , agronomy , organic chemistry , nitrogen , inorganic chemistry , biochemistry , environmental science , soil science , biology , ecology , agriculture
Summary As a source of organic matter, crop residues affect the behaviour of pesticides in agricultural soils. The fate of [U‐ring‐ 13 C] and [U‐ring‐ 14 C] atrazine (6‐chloro‐N‐ethyl‐N‐isopropyl‐1,3,5‐triazine‐2,4‐diamine) was investigated during laboratory incubation under controlled conditions in a loamy soil amended with wheat straw at two different states of decomposition: no preliminary decomposition or 6 months’ preliminary decomposition. After 3 months, non‐extractable, so‐called ‘bound’, 13 C‐atrazine residues were recovered in three particle‐size fractions (> 200, 50–200 and < 50 μm), and investigated with solid‐state 13 C‐NMR spectroscopy. Parallel incubations with [U‐ring‐ 14 C] atrazine were carried out to quantify the bound residues as well as the extractable and mineralized fractions. The effect of straw residues on atrazine behaviour depended on whether they had been previously decomposed or not. When straw was decomposed for 6 months prior to incubation, atrazine mineralization was enhanced to 50% of the initial 14 C in contrast to 15% of the initial 14 C in soil alone and soil amended with fresh straw. In parallel, atrazine bound residues were formed in greater amount representing up to 20% of the initial 14 C. CP/MAS 13 C‐NMR on soil size fractions of soil–straw mixtures after incubation with 13 C‐atrazine showed that bound residues contained mostly triazinic C, corresponding to atrazine or primary metabolites. Non‐humified organic materials recovered in size fractions > 200 and 50–200 μm contained significant amounts of bound residues, especially when straw was added to the soil. CP/MAS 13 C‐NMR analysis of humic acids obtained from < 50‐μm fractions was difficult due to overlapping of the native carboxyl 13 C signal with the 13 C‐atrazine signal.