Division soil and water management, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
Environ Pollut. 2010 May;158(5):1405-11. doi: 10.1016/j.envpol.2009.12.041. Epub 2010 Jan 29.
Pesticide transport models commonly assume first-order pesticide degradation kinetics for describing reactive transport in soil. This assumption was assessed in mini-column studies with associated batch degradation tests. Soil mini-columns were irrigated with atrazine in two intermittent steps of about 30 days separated by 161 days application of artificial rain water. Atrazine concentration in the effluent peaked to that of the influent concentration after initial break-through but sharply decreased while influx was sustained, suggesting a degradation lag phase. The same pattern was displayed in the second step but peak height and percentage of atrazine recovered in the effluent were lower. A Monod model with biomass decay was successfully calibrated to this data. The model was successfully evaluated against batch degradation data and mini-column experiments at lower flow rate. The study suggested that first-order degradation models may underestimate risk of pesticide leaching if the pesticide degradation potential needs amplification during degradation.
农药运移模型通常假定一级农药降解动力学来描述土壤中的反应性运移。本研究通过小型土柱实验和相关的批式降解实验对此假设进行了评估。在两个间歇性步骤中，用莠去津对小型土柱进行灌溉，每个步骤约 30 天，中间间隔 161 天施加人工雨水。在初始穿透后，流出物中的莠去津浓度达到与流入物浓度相同，但在流入物持续供应时，浓度急剧下降，表明存在降解滞后阶段。在第二步中也出现了同样的模式，但流出物中莠去津的峰值高度和回收率较低。带有生物量衰减的 Monod 模型成功地对该数据进行了校准。该模型还成功地对较低流速下的批式降解数据和小型土柱实验进行了评估。研究表明，如果农药在降解过程中需要放大其降解潜力，那么一级降解模型可能会低估农药淋溶的风险。
