Bromoxynil is a widely used nitrile herbicide applied to maize and other cereals in many countries. To date, still little is known about bromoxynil turnover and the structural identity of bromoxynil non-extractable residues (NER) which are reported to occur in high amounts. Therefore, we investigated the microbial turnover of ¹³C-labeled bromoxynil for 32 days. A focus was laid on the estimation of biogenic NER based on the turnover of ¹³C into amino acids (AA). At the end, 25% of ¹³C₆-bromoxynil equivalents were mineralized, 2% assigned to extractable residues and 72.5% to NER. Based on 12% in the ¹³C-total AA and an assumed share of AA of 50% in microbial biomass we arrived at 24% of total ¹³C-biogenic NER. About 33% of the total ¹³C-NER could thus be explained by ¹³C-biogenic NER; 67% was unknown and by definition xenobiotic NER with potential for toxicity. The ¹³C label from ¹³C₆-bromoxynil was mainly detected in the humic acids (28.5%), but significant amounts were also found in non-humics (17.6%), fulvic acids (13.2%) and humins (12.7%). The ¹³C-total amino acids hydrolyzed from humic acids, humins and fulvic acids amounted to 5.2%, 6.1% and 1.2% of ¹³C₆-bromoxynil equivalents, respectively, corresponding to total ¹³C-biogenic NER amounts of 10.4%, 12.2% and 2.4%. The humins contained mostly ¹³C-biogenic NER, whereas the humic and fulvic acids may be dominated by the xenobiotic NER. Due to the high proportion of unknown ¹³C-NER and particularly in the humic and fulvic acids, future studies should focus on the detailed characterization of these fractions.

溴苯腈是在许多国家中广泛用于玉米和其他谷物的腈类除草剂。迄今为止，人们对溴苯腈的周转率和溴苯腈不可提取残基（NER）的结构特征知之甚少，据报道这些残留物数量很高。因此，我们调查了32天¹³ C标记的溴苯腈的微生物更新。重点放在了基于¹³ C转化为氨基酸（AA）的生物型NER的估算上。在结束时，25％的^13个C ^ _6个-bromoxynil当量矿化，分配给可提取残余物和72.5％至NER 2％。根据¹³ C总AA中的12％和假定的AA在微生物量中占50％的假设，我们得出了总^{13 A中的}24％C-生物基因NER。因此，在全部¹³ C-NER中，约有33％可以用¹³ C-生物源NER来解释。未知的占67％，根据定义，异种NER可能具有毒性。来自¹³ C _6-溴苯甲腈的¹³ C标记主要在腐殖酸中检出（28.5％），但在非腐殖质（17.6％），黄腐酸（13.2％）和腐殖质（12.7％）中也发现大量。从腐殖酸，腐殖质和富里酸水解得到的¹³ C总氨基酸分别占¹³ C _6-溴苯腈当量的5.2％，6.1％和1.2％，对应于总¹³C-生物NER量为10.4％，12.2％和2.4％。腐殖质主要含有¹³ C-生物源性NER，而腐殖酸和黄腐酸可能是异源NER所主导。由于未知的¹³ C-NER的比例很高，尤其是在腐殖酸和黄腐酸中，未来的研究应集中在这些馏分的详细表征上。