Reducing environmental pollution from veterinary pharmaceuticals in the runoff from swine farms

加拿大是世界第二大猪肉出口国，2005年出口了超过100万吨猪肉，价值近30亿美元。畜牧业的增长之所以成为可能，主要是由于集约化畜牧经营的出现。然而，它们也成倍地增加了废物产生的数量和速度。例如，1986年至1996年间，加拿大的粪便产量增加了75%，从而增加了土壤、水和空气污染的风险。2001年加拿大的年粪便产量为1.775亿吨。兽医药物（VPs）在国际畜牧组织中经常使用，不仅用于控制牲畜疾病，而且还用于促进牲畜生长。然而，大多数vp在动物的肠道中吸收不良，平均降解率为50%，在欧洲和北美，每年约有8000吨vp未被动物粪便和尿液代谢，从而污染了环境。因此，迫切需要对粪便中VPs的环境风险进行调查。它们还可能通过杀死易受影响的微生物而增加农药在土壤中的半衰期，从而显著影响其微生物降解。非常需要进行研究，以确定这些微污染物在较冷的加拿大环境中的命运和迁移。土壤中的优先流可能是造成浅层地下水和地表水污染的重要原因。数学模型不仅可以模拟土壤中VPs的命运和迁移，还有助于制定减少污染的最佳管理措施。堆肥、好氧或厌氧消化和植物过滤条也可以最大限度地减少vp对环境的污染。

Canada is the world's second largest pork exporter with over 1 million tonnes of pork exported in the year 2005, valued at almost $3 billion. The growth in the livestock industry has been possible mainly due to the advent of intensive livestock operations (ILOs). However, they have also increased the quantity and rate of waste production exponentially. For example, manure production rates have increased by as much as 75% between 1986 and 1996 in Canada, thereby heightening the risk of soil, water and air pollution. The annual manure production in Canada was 177.5 million tonnes in 2001.     Veterinary pharmaceuticals (VPs) are used routinely in ILOs not only to control livestock diseases, but also to promote livestock growth. Most VPs, however, are poorly absorbed in the animal's gut and, with an average degradation rate of 50%, approximately 8000 tons of VPs, given annually to animals in Europe and North America, remain unmetabolized in animal feces and urine, thereby polluting environment.    Therefore, investigations are urgently needed to investigate the environmental risks posed by VPs in manure. They could also be increasing the half-life of pesticides in soil by killing the susceptible microorganisms and thus significantly affecting their microbial degradation. There is a great need to carry-out studies in order to determine the fate and transport of these micro-pollutants in the colder Canadian environment.    Preferential flow in soils may be playing a big role in causing groundwater pollution of shallow groundwater and surface water bodies. Mathematical modeling can not only simulate the fate and transport of VPs in soil but also help in the development of best management practices to reduce pollution. Composting, aerobic or anaerobic digestion, and vegetated filter strips may also minimize environmental pollution from VPs.