3,4-Dichloroaniline revisited: A study on the fate of the priority pollutant in a sediment-water system derived from a rice growing region in Italy.
As ultimate sink for xenobiotics released into the environment, sediments play an important role concerning the evaluation of the fate of foreign compounds. 3,4-Dichloroaniline (3,4-DCA) is a degradation product of herbicide propanil and some urea herbicides. Propanil was extensively used worldwide in rice cultivation. The aim of the study was to examine the fate of14C-labeled 3,4-DCA in a sediment-water system; the sediment was derived from a rice field in Northern Italy. After application of14C-3,4-DCA, a time-course study was performed using incubation periods from 4h to 56days. Fractions obtained from assays were water phase, sediment phase including methanol and Soxhlet extract as well as non-extractable residues (NER), and mineralized portion (14CO2). Soluble fractions were examined by TLC, HPLC and GC-MS. NER found in sediment phases were further fractionated in non-humics, humic acids, fulvic acids and humin. Stability of systems was checked by microbial activity, dissolved oxygen and pH. After 56days of incubation, 23.1% of applied14C was mineralized, only 1.30% remained in the water phase, whereas 60.8% was found in the sediment phase, 53.3% of which were NER. Minor metabolites identified were 3,4-dichloroacetanilide (3,4-DCAA) and 3,3',4,4'-tetrachloroazobenzene (TCAB; 2.63% after 56days). According to pH, dissolved oxygen and microbial activity, systems appeared to be stable and not influenced by applied 3,4-DCA. Most striking result was the high mineralization rate as compared to previously published data. This finding suggested an adaptation of the microbial community in the sediment possibly due to decade-long treatment of rice fields with propanil.
Institute of Biology V, RWTH Aachen University, D-52056 Aachen, Germany.
Ye
Y
Yuan
Institute of Biology V, RWTH Aachen University, D-52056 Aachen, Germany.
Peng
P
Zhang
Institute of Biology V, RWTH Aachen University, D-52056 Aachen, Germany.
Andreas
A
Schäffer
Institute of Biology V, RWTH Aachen University, D-52056 Aachen, Germany. Electronic address: burkhard.schmidt@post.rwth-aachen.de.
Burkhard
B
Schmidt
3,3′,4,4′-Tetrachloroazobenzene; 3,4-DCA mineralization; 3,4-DCA non-extractable residues; 3,4-Dichloroacetanilide; 3,4-Dichloroaniline (3,4-DCA); Rice field; Sediment-water system