Modeling of rhizosphere influences on interactions between chemical dynamics and effects of veterinary medicines in soil

第一阶段建立的模拟模型整合了兽药磺胺嘧啶（SDZ）和双氟沙星（DIF）在土壤中的化学命运，以及它们在单剂量施用后对土壤微生物和土壤功能的影响。在第二个项目阶段，该方法将扩展到根际，根际是土壤中微生物生长的热点，也是活跃根系释放有机化合物的连续来源。抗生素及其主要代谢物的快、慢吸附、转化和结合残基形成过程适应于根际环境。建立的土壤功能、结构多样性和抗性动态效应模型通过与实验子项目密切合作的相关植物-土壤相互作用得到扩展。综合命运效应模型与考虑根际异质性和植物吸收的转运模型相结合。利用中央中尺度试验和几个计划中的卫星试验数据，对根际和块状土壤中两种抗生素SDZ和DIF的过程进行了参数化。所得的综合命运效应模型将用现场试验的数据进行评估。该模型进一步用于制定抗生素诱导效应的结构弹性和功能冗余等指标，评估其在风险评估中的适用性，并产生新的假设来证实结论。

The simulation models developed in the 1st phase integrate the chemical fate of the veterinary medicines sulfadiazine (SDZ) and difloxacin (DIF) in bulk soil and their subsequent effects on soil microorganisms and on soil functions after single-dose application with manure. In the 2nd project phase, this approach is extended to the rhizosphere, which represents the hotspot of microbial growth in soil and a continuous source of organic compounds released from active roots. The processes of fast and slow sorption, transformation and formation of bound residues of the antibiotics and their main metabolites are adapted to the rhizosphere. The developed effect models for soil functions, structural diversity, and resistance dynamics are extended by relevant plant-soil interactions in close collaboration with the experimental subprojects. The integrated fate-effect model is coupled with a transport model taking heterogeneities of the rhizosphere and plant uptake into account. Processes are parameterized for the two antibiotics SDZ and DIF in rhizosphere and bulk soil with data from the central mesocosm experiment and several planned satellite experiments. The resulting integrated fate-effect models will be evaluated with data from the field experiments. The model is further used to develop indicators such as structural resilience and functional redundancy for antibiotic induced effects, evaluate their applicability for risk assessment and to generate new hypotheses to corroborate the conclusions.