Characterizing the fate of antimicrobials in manure and agricultural soils

加拿大畜牧业每年使用约100万公斤抗菌活性成分用于治疗性给药和亚治疗性生长促进。抗菌剂很容易被排泄出来，因此在粪便中可以检测到。含有抗菌剂和其他有机污染物的畜禽粪便不经前处理就被施于农业土壤中。草原农民需要粪便来循环养分，增加碳投入，以改善土壤健康。粪便还可以增加碳固存，以缓解气候变化，并有助于加拿大实现到2050年实现净零排放的承诺。然而，粪便在农业生态系统中传播抗菌剂，这可能会对生态系统的功能产生负面影响，并与抗生素耐药性有关。抗生素耐药性是世界卫生组织于2020年宣布的全球十大突发公共卫生事件之一，给国民经济带来了非常高的成本，也给卫生保健系统带来了负担。如果粪便继续传播抗菌剂，它们对环境和人类健康的不利影响将威胁到草原畜牧业种植系统的未来。因此，现在采取行动降低畜牧业排放到更广泛环境中的抗菌剂是至关重要的。我的长期研究目标是确定农业来源污染物在农业生态系统中的命运，以推进加拿大草原可持续作物-牲畜系统的粪便管理战略：包括抗菌剂、类固醇激素、生长促进剂、微量元素和过量营养的运输、吸收和降解。我的研究产生的数据将导致在农场层面的直接应用，提高草原条件下污染物传输模型的预测能力，并有助于开发相关的政策工具。实现上述目标的短期目标是：(1)量化春季解冻融雪径流和(2)降雨径流和淋溶在多大程度上有助于溶解的和与沉积物结合的兽用抗菌剂、抗微生物降解产物和抗菌剂耐药基因在猪粪改良农田内的传输；(3)优化常用兽用抗菌剂、抗微生物降解产物和抗生素抗药性基因在猪粪好氧堆肥过程中的降解动力学。拟议的研究将产生科学合理的农场牲畜粪便管理战略和促进农业可持续发展的政策工具。该计划将在土壤科学、环境化学、分析化学、分子生物学、实验设计、数据分析、数据解释和研究交流方面培训一名硕士、两名博士和十名本科生(每年两名实习生)。该计划还将为学员提供职业发展和建立网络的机会。

The Canadian livestock industry annually uses about one million kg of antimicrobial active ingredients for therapeutic administration and sub-therapeutic growth promotion. Antimicrobials are readily excreted and hence detected in manures. Livestock manure laden with antimicrobials and other organic contaminants is applied to agricultural soils without pre-treatment. Prairie farmers need manure to recycle nutrients and increase carbon inputs to improve soil health. Manure can also increase carbon sequestration to mitigate climate change and help Canada's pledge to net-zero emissions by 2050. However, manures spread antimicrobials in the agroecosystem, which can negatively affect the ecosystem's functioning and are linked to antibiotic resistance. Antibiotic resistance is one of the top ten public health emergencies facing the world, declared by the World Health Organization in 2020, and comes at a very high cost to national economies and a burden to the health care systems. If manures continue to spread antimicrobials, their adverse effects on the environment and human health will threaten the future of the prairie livestock cropping systems. Thus, it is critical to act now to lower antimicrobials discharging into the broader environment from livestock operations. My long-term research goal is to characterize the fate of contaminants of agricultural origin in the agroecosystem to advance manure management strategies for sustainable crop-livestock systems in the Canadian Prairies: including the transport, sorption, and degradation of antimicrobials, steroidal hormones, growth promotants, trace elements, and excess nutrients. Data generated by my research will lead to direct applications at the farm level, improve the predictive ability of contaminant transport models under prairie conditions, and aid in developing related policy tools. The short-term objectives to accomplish the above goals are to (1) quantify the extent to which spring-thaw snowmelt runoff and (2) rainfall-runoff and leaching contribute to the transport of dissolved and sediment-bound veterinary antimicrobials, antimicrobial degradation products, and antimicrobial-resistant genes within swine manure-amended cropland; (3) optimization of degradation kinetics of commonly used veterinary antimicrobials, antimicrobial degradation products, and antibiotic-resistant genes during aerobic swine manure composting. The proposed research will generate scientifically sound on-farm livestock manure management strategies and policy tools for sustainability in agriculture. The program will train one MSc, two PhD, and ten undergraduate students (two trainees per year) in soil science, environmental chemistry, analytical chemistry, molecular biology, experiment designs, data analysis, data interpretation, and research communication. The program will also provide opportunities for professional development and networking for the trainees.