【作者】 石冬冬；

【导师】 石波；

【作者基本信息】 中国农业科学院 ， 农产品质量与食物安全， 2012， 博士

【摘要】 莠去津是选择内吸型除草剂,广泛应用于玉米的种植中。本研究通过对饮水、精料补充料、青贮玉米和生鲜乳中莠去津(ATZ)及其主要代谢物(T-ATZ)浓度的监测分析,对ATZ经降解和代谢后在奶牛饮食中的实际污染现状及T-ATZ在生鲜乳中的残留规律进行研究,从而为饲料中残留的T-ATZ对生鲜乳安全性的影响提供评价依据。1、研究建立了饮水、青贮玉米、精料补充料及生鲜乳四种不同样品中ATZ及其六种主要代谢产物(DEA, DIA, DACT, HA, DEHA和DIHA)的同时检测方法,并对方法的性能进行了检验与确证。结果显示,四种方法的LOD, LOQ、加标回收率和精密度均达到了欧盟SANCO12495-2010的质量要求。2、通过对采自A、B、C三个地区的生鲜乳实际生产中的奶牛饮水、青贮玉米及精料补充料中T-ATZ含量的分析,对其中T-ATZ的残留情况进行了初步研究。所采集的奶牛饮水中T-ATZ残留浓度很低,其中残留有ATZ和DEA；青贮玉米中DEHA的残留量最高,其次为HA,只在少量样品中检出DEA和DIA；精料补充料中均有ATZ及DEHA HA、DEA的残留,HA的残留量最高,ATZ、DEHA及DEA残留量相当。C地区样品中T-ATZ的残留水平明显高于其他两地区。3、研究了青贮过程中和青贮后存放期间T-ATZ的转化和降解规律外源添加的ATZ和秸秆中自然残留的T-ATZ在青贮过程中的转化和降解研究显示,外源添加的ATZ和自然残留的T-ATZ在青贮过程中均发生了较快的降解,青贮特别是青贮时添加青贮剂可有效地降低青贮饲料中ATZ及其毒性较高的脱烷基代谢物的浓度。开窖后存放期间,T-ATZ仍呈显著下降趋势,但90天后下降趋缓,所以青贮后的存放过程有利于T-ATZ继续向低毒降解。4、通过对河北省廊坊地区的9个奶牛养殖户两个时间段生产的监测,确定了监测期内T-ATZ在奶牛饮食及生鲜乳中的污染情况,并对T-ATZ在生鲜乳中的残留规律进行了研究。在两个监测期,饮水中的T-ATZ的残留很低,可以忽略不计,青贮饲料是T-ATZ的主要残留污染来源。在第一期饲料(青贮饲料+精料补充料)样品中,主要残留有ATZ和HA；第二期样品中主要残留有DEHA;DEA在两个监测期中残留比例均较高。在第一期生鲜乳样品中,HA、DEA和ATZ比例相当,DACT有较低残留；第二期样品中DEA的残留比例明显高于其他残留物。ATZ及其脱烷基代谢物残留规律研究显示：饲料中T-ATZ含量较高时,其在生鲜乳中的残留率为1.02%,含量较低时,残留率为5.21%。生鲜乳中ATZ及其脱烷基代谢物的浓度有超过某些国家MRL值的风险。因此,饲料中ATZ及其脱烷基代谢物的残留可能给生鲜乳的安全性带来影响。HA残留规律研究显示：HA在生鲜乳中的最高残留量为2.35μg/kg,在饲料中HA含量较高时,最大残留率仅为1.21%。HA的残留对生鲜乳的安全影响不大。更多还原

【Abstract】 Atrazine is an inner absorption type herbicide widely used in corn production. The purpose of this study was to provide the base for evaluating the effects of atrazine and its major metabolites(T-ATZ) in dairy cattle feed on the safety of raw milk. Focusing on the critical points of the food chain, the studies were conducted on the T-ATZ pollution level in dairy cattle feed and raw milk, their degradation and left over pattern of T-ATZ between them by monitoring of T-ATZ in drinking water, corn silage, supplementary feed and raw milk from practical production.1. The development and validation of the LC-MS/MS methods for simultaneous determining atrazine and its six metabolites (DEA, DIA, DACT, HA, DEHA and DIHA) in drinking water, corn silage, supplementary feed and raw milk. All of the basic performance parameters of the methods, LOD, LOQ, recovery and precision could meet the requirements of EU SANCO12495-2011.2. Preliminary study on the existing forms and residue levels of T-ATZ in drinking water, corn silage, supplementary feed used in practical production was conducted by analyzing different kinds of samples collected from A, B and C regions.The results of T-ATZ showed that ATZ and DEA accounted for the major residues of the cow drinking water, but their concentrations were much lower than all existing MRL standards. In corn silage, DEHA accounted for a greater proportion of the metabolites than HA; DEA and DIA can only be found in a few of samples. In supplementary feed, ATZ and DEHA、HA、DEA residues could be found in all collected samples; HA made the major proportion of the residues, ATZ, DEHA and DEA could also be found and the their concentrations were almost the same. In contrast to the residual results of A and B region, the residual level of C region was significant higher.3. Study on the degradation and transition of T-ATZ during corn ensilage and the silage storage.Two experiments were conducted for the ensiling fermentation. One was adding ATZ compound directly to blank corn straw before ensilage. Another was using corn straw with natural T-ATZ residues for the ensilage. The results indicated ensilage and using ensilage agent in the process could efficiently decrease ATZ and its dealkylated metabolites with high toxicity in corn silage and improve the security of the crude feed. The study of degradation and transition during silage storage illustrated the total concentration of T-ATZ still decreased, but after90days from the silo opening, the changes were slowdown. T-ATZ more liked to degrade into the low toxicity form.4. To confirm the major existing forms and residue levels of T-ATZ in dairy cattle diet and in the raw milk, the practical production of nine dairy farmers in the Lang Fang district were monitored at two periods. And the residual regular patterns of T-ATZ in raw milk were studied based on the results.The monitor Data demonstrated either in the initial period or in4months of the silage silo opening, silage feed in the diet was the major source of T-ATZ of the milk. As time went on, the effects from the supplementary feed would grow up. In the initial period major residues in feeds (including silage and supplementary feed) were ATZ and HA, while in the second period DEHA accounted for a large proportion of the residues, DEA kept a higher residual proportion in the two periods. For the raw milk, HA, DEA and ATZ were the major residual forms. But with passing of time, DEA level increased gradually and became the most pollutant in the second period.The study illustrated:when the residue level of ATZ and its dealkylated metabolites in feed was high, their transfer rate to the raw milk was1.02%, but when the level was low, their transfer rate was5.21%. It seems that the concentrations of ATZ and its dealkylated metabolites in raw milk might be able to exceed10μg/kg which is the MRL value of Australian. Obviously, ATZ and its dealkylated metabolites in feed were a critical potential safety hazards to the raw milk.As to the HA, the maximum transfer rate from feed to raw milk was1.02%and the highest level in milk monitored in this study was2.35μg/kg. Obviously, HA in feed did not pose a threat to milk since the toxicity of HA is much lower than ATZ.更多还原