Watanabe Naoko, Harter Thomas H, Bergamaschi Brian A
Dep. of Land, Air and Water Resources, Veihmeyer Hall, Univ. of California, Davis, CA 95616-8628, USA.
J Environ Qual. 2008 Sep-Oct;37(5 Suppl):S78-85. doi: 10.2134/jeq2007.0371.
Pharmaceuticals used in animal feeding operations have been detected in various environmental settings. There is a growing concern about the impact on terrestrial and aquatic organisms and the development of antibiotic-resistant strains of microorganisms. Pharmaceutical use in milking cows is relatively limited compared with other livestock operations, except for the ionophore monensin, which is given to lactating cows as a feed. By weight, monensin can be the most significant antibiotic used in a dairy farm. This study investigates the potential of monensin to move from dairy operations into the surrounding ground water. Using two dairy farms in California as study sites, we twice collected samples along the environmental pathway-from flush lanes, lagoon waters, and shallow ground water beneath the dairies and beneath its associated manured fields. Monensin concentrations were determined using solid-phase extraction and liquid chromatography-tandem mass spectrometry with positive electrospray ionization. Monensin was detected in all of the flush lane and lagoon water samples. Theoretical maximum concentration estimated from the actual dosing rate and the theoretical excretion rate assuming no attenuation was one order of magnitude greater than observed concentrations, suggesting significant attenuation in the manure collection and storage system. Monensin was also detected, at levels ranging from 0.04 to 0.39 microg L(-1), in some of the ground water samples underneath the production area of the dairy but not from the adjacent manured fields. Concentrations in ground water immediately downgradient of the lagoons were one to two orders of magnitude lower than the concentrations detected in lagoons, suggesting attenuation in the subsurface. The data suggest the possibility of monensin transport into shallow (2-5 m) alluvial ground water from dairy management units, including manure storage lagoons and freestalls occupied by heifers, lactating cows, and dry cows.
在各种环境中都检测到了用于动物饲养作业的药物。人们越来越担心其对陆地和水生生物的影响以及微生物耐药菌株的产生。与其他畜牧作业相比，奶牛挤奶过程中的药物使用相对有限，但离子载体莫能菌素除外，它作为饲料喂给泌乳奶牛。按重量计算，莫能菌素可能是奶牛场使用的最重要的抗生素。本研究调查了莫能菌素从奶牛场进入周围地下水的可能性。以加利福尼亚州的两个奶牛场为研究地点，我们沿着环境路径两次采集样本，包括冲洗通道、泻湖水以及奶牛场及其相关施肥田地下方的浅层地下水。使用固相萃取和正电喷雾电离液相色谱 - 串联质谱法测定莫能菌素浓度。在所有冲洗通道和泻湖水样本中都检测到了莫能菌素。根据实际给药率和假设无衰减的理论排泄率估算的理论最大浓度比观测浓度高一个数量级，这表明在粪便收集和储存系统中存在显著衰减。在奶牛生产区域下方的一些地下水样本中也检测到了莫能菌素，浓度范围为0.04至0.39微克/升，但相邻施肥田地下方的地下水样本中未检测到。泻湖下游紧邻处的地下水中的浓度比泻湖中检测到的浓度低一到两个数量级，这表明在地下存在衰减。数据表明莫能菌素有可能从奶牛管理单元，包括粪便储存泻湖以及由小母牛、泌乳奶牛和干奶牛占据的自由牛舍，进入浅层（2 - 5米）冲积层地下水。
