Improving understanding of veterinary medicine degradation and fate in manures and anaerobic digestion plants

自20世纪90年代末S(Hling-Sorensen等人，1998年)以来，人们一直在调查环境中兽药的存在，尽管我们仍然对它们在环境中的命运知之甚少(Grant等人，2012年；Slana和Sollner Dollenc，2013年；Jechalke等人，2014年)。这一点很重要，因为兽药管理局有必要对兽药进行环境风险评估，并采取适当措施减轻可能对环境造成的负面影响。此外，欧盟水框架指令(WFD)要求河流具有良好的生态状况，由于我们目前对兽药等新兴污染物的了解有限，这不太可能实现。兽药通常在牲畜体内代谢不良(Sarmah等人，2006年)，有可能在粪便、土壤和水中持续存在，全年在水体中检测到的浓度从每升几百微克到几十微克不等(例如Boxall等人，2006年；利塞莫尔等人，2006年)。基于有限的可用数据(Kolodziejska等人，2013年)，因此可能会对生态造成影响，我们需要更好地了解减少这些影响的备选方案。该项目将进行测试的中心假设是，随着对兽药退化途径的更好理解，我们可以通过使用特定的管理方案来缓解环境影响。这些措施可能包括粪便储存、农场厌氧消化器的使用，以及避免半衰期最长的化合物。具体工作包(WPS)将调查粪便类型和变异性对降解率(WP1)的影响，粪便储存设施(包括农场厌氧消化)对兽药命运(WP2)的影响，以及粪便施用方法(WP3)的效果。根据高使用率和与可能使用兽药的不同情景的相关性，选择了潜在的研究化合物。土霉素、磺胺嘧啶、头孢硫呋喃和氟苯达唑可能是被研究的特定化合物。对于WP1，将使用批量降解实验来提供目前无法获得的研究化合物在不同粪便中的持久性数据；松鸡和绵羊的粪便、牛和家禽的粪便以及猪浆。我们在这里的目标是制定更强有力的粪便降解指南和方法，用于环境风险评估。然后，将使用实验室淋滤柱来研究测试物质从粪便中的释放及其在土壤中的淋溶。进一步的小区研究将被用来评估粪便类型如何影响陆上流动中兽药的损失。利兹和FSL之间的合作确保了有足够的实验设施来进行这一系列具有挑战性的实验。厌氧消化越来越多地被用于农场产生沼气，实地研究将确定对FSL(WP2)已经使用的农场的退化的影响。对于WP3，利兹大学农场的地块规模调查将在耕地和牧场上进行，使用表层和地下(注入)肥料。环境样品中兽药浓度的所有分析将在FSL使用该国最大的最先进的液质联用(LC-MS)设备之一进行。

The presence of veterinary medicines in the environment has been investigated since the late 1990's (Halling-Sorensen et al., 1998) although we still know very little about their environmental fate (Grant et al., 2012; Slana and Sollner Dollenc, 2013; Jechalke et al., 2014). This is important as the Veterinary Medicines Directorate necessitates that veterinary medicines are assessed for environmental risk and appropriate measures are put in place to mitigate against suspected negative environmental impacts. Moreover, the EU Water Framework Directive (WFD), requires that rivers are of good ecological status and this is unlikely to be achieved with our currently limited knowledge of emerging pollutants such as veterinary medicines. Veterinary medicines are often poorly metabolised by livestock (Sarmah et al., 2006), have the potential to persist in manure, soil and water and have been detected in waterbodies throughout the year at concentrations ranging from several hundred up to tens of micrograms per litre (e.g. Boxall et al., 2006; Lissemore et al., 2006). Based on the limited available data (Kolodziejska et al., 2013), it is therefore possible that impacts on ecology may be resulting and that we need improved understanding of options to reduce these.The central hypothesis that the project will test is that with an improved understanding of veterinary medicine degradation pathways we can mitigate environmental impacts by adopting the use of particular management options. These may include manure storage, use of on-farm anearobic digestors, and avoidance of compounds with the longest half-lives. Specific work packages (WPs) will investigate the affect of manure type and variability on degradation rates (WP1), the influence of manure storage facilities including on-farm anaerobic digestion on veterinary medicine fate (WP2), and the effect of manure application methods (WP3). Potential study compounds have been selected based on high usage and relevance to the different scenarios in which veterinary medicines may be used. Oxytetracycline, sulphamethazine, ceftiofur and flubendazole are likely to be the specific compounds investigated. For WP1 batch degradation experiments will be used to provide currently unavailable persistence data for the study compounds in different manures; grouse and sheep droppings, cattle and poultry manures, and pig slurry. We aim here to develop more robust guidance and methodologies for manure degradation for use in environmental risk assessments. Laboratory leaching columns will then be used to investigate the release of the test substances from the manures and their leaching through soil. Additional plot studies will be used to assess how manure type affects losses of veterinary medicines in overland flow. The collaboration between Leeds and FSL ensures that sufficent experimental facilities are available to carry out this challenging range of experiments. Anaerobic degestion is increasing being used on farms to generate biogas and field studies will determine the impact on degradation at a farm already used by FSL (WP2). For WP3, plot scale investigations at the University of Leeds' farm will be undertaken on arable and pasture land using both surface and sub-surface (injection) applications of manure. All analyses of veterinary medicine concentrations in environmental samples will be undertaken at FSL using one of the largest state of the art Liquid Chromatography-Mass Spectrometry (LC-MS) facilities in the country.