Metabolization/ bound residues and mineralization of veterinary antibiotic residues in soil under dynamic soil moisture and temperature conditions

该项目的最终目标是在实验室研究中生成不同温度和土壤湿度条件下兽医抗生素残留的矿化，代谢和结合残留物形成的数据，并与实地研究进行比较，以充分了解所施用药物在土壤中的命运和效果。含有14c标记磺胺嘧啶（SDZ）及其生物转化产物的粪便将在包含三种处理的孵育实验中与Merzenhausen土壤混合。第一次处理将在静态温度和恒定含水量为持水量40%的条件下进行。在第二次处理中，我们将使用相同的湿度条件，但温度将在±10°C的范围内变化。第三次处理将在恒温条件下进行，模拟干旱和暴雨。所有处理的放射性平衡将被确定，土壤将通过重复的ASE（加速溶剂萃取）提取。除了对可逆隔离残留物进行LC-MS/MS分析外，不可提取部分将在碱性条件下溶解，并通过HPSEC（高效粒径排除色谱）和与质谱仪在线耦合的放射性检测器进行研究，以阐明土壤中SDZ残留物的化学性质。额外的15n标记SDZ的培养实验将通过液体和固体15N-NMR来研究结合残留物的化学性质。这一分析将阐明在不同的小气候条件下，有多少施用药物被物理捕获或共价结合到土壤化合物上的问题。此外，我们将通过MALDI-MS成像分析根表面（根平面），以定位SDZ及其代谢物在高活性微位点的浓度，分辨率为50-100 μm。我们将把结果与生物测量确定的高活性微位点进行比较。

The ultimate goal of the proposed project is to generate data on the mineralization, metabolization and bound residue formation of veterinary antibiotic residues under varying temperature and soil moisture conditions in a laboratory study in comparison to a field study to fully understand the fate and effects of the applied drug in soil. Manure containing 14C-labelled sulfadiazine (SDZ) and its bio transformed products will be mixed with Merzenhausen soil in an incubation experiment encompassing three treatments. The first treatment will be carried out under static temperature and constant moisture content of 40% of the water holding capacity. In the second treatment, we will use the same moisture conditions but the temperature will be varied within a range of ±10°C. The third treatment will be conducted under constant temperature with a simulation of drought and heavy rain. The radioactivity balance will be determined for all treatments and the soil will be extracted by repeated ASE (accelerated solvent extraction). In addition to LC-MS/MS analysis of the reversible sequestered residues, the non-extractable part will be dissolved under alkaline conditions and investigated by HPSEC (high performance size exclusion chromatography) and a radioactivity detector coupled online to a mass spectrometer to elucidate the chemical nature of the SDZ residues in soil. Additional incubation experiments with specifically 15N-labeled SDZ will be carried out to investigate the chemical nature of bound residues by liquid and solid state 15N-NMR. This analysis will shed light on the question how much of the applied drug is physically trapped or covalently bound to soil compounds under variable microclimatic conditions. Furthermore we will analyze the root surface (rhizoplane) by means of MALDI-MS imaging in order to localize the concentration of SDZ and its metabolites in highly active micro sites with a resolution of 50–100 μm. We will compare the results with highly active micro sites as determined by biological measurements.