Pharmaceutical Sorption to Model Soil Components

人类和兽药化合物越来越多地在许多环境介质中被检测到，包括土壤、沉积物、地下水和地表水。目前尚不清楚人类和生物体将如何适应日益增加的环境暴露于这些生物活性化合物中。令人关注的健康影响包括抗生素耐药性的扩散、内分泌干扰活动和非目标生物的不良反应。假设与目标：除了与天然有机物的相互作用外，我们假设药物对土壤和沉积物的吸附受3种机制的控制：(1)矿物表面上带相反电荷的位置的静电吸引；(2)与铝硅酸盐粘土矿物的阳离子交换反应；(3)与铁、铝氧化物的表面络合反应。提出的研究的最终目标是定量描述药物的吸附粘土和氧化物土壤矿物基于吸附现象的机理理解。方法：研究目标将通过研究药物对模型吸附剂的吸附来实现，这样就可以独立地探测真实土壤或沉积物样品中存在的吸附剂相。将使用五种模型吸附剂：2层和3层粘土（高岭石和蒙脱土），铁和铝氧化物。使用较多的兽用抗生素土霉素、环丙沙星、FCQA和Enro-CO2（环丙沙星的亚结构）将被用作测试山山酸盐，因为农业抗生素的使用代表了最集中的药物释放到环境中。该研究结果可用于从化合物性质（溶液络合常数）和吸附剂特性（给定pH/离子强度下的表面化学）预测药物吸附。研究意义和效益：本研究将提供首个重要兽用抗生素化合物固水分配的机制模型。为高纯度吸附剂开发的定量模型可以适用于开发任何土壤或沉积物阶段的一般分配模型。对土壤和沉积物-水分配的准确描述将有助于解释在地表水和地下水中药物化合物环境浓度的实地调查中观察到的药物分布，包括我们的山梨酸测试（USGS有毒物质水文计划）。最终，这里开发的药物吸附定量模型可以用于环境命运模型，该模型与毒理学模型相结合，将能够准确评估兽药释放到水生环境所带来的风险。教育效益：将本科生纳入研究活动将为这些学生提供与教师密切合作解决开放式研究问题的机会。拟议的研究也将为康涅狄格大学和杜克大学的环境、制药和农业项目之间未来的综合研究活动奠定基础。

0225696 MacKay Human and veterinary pharmaceutical compounds are detected increasingly in many environmental media, including soils, sediments, groundwaters and surface waters. It is unknown how humans and organisms will adapt to increasing environmental exposures to these bioactive compounds. Health effects of concern include the spread of antibiotic resistance, endocrine disrupting activity and adverse responses in non-target organisms.Hypothesis and Goal: In addition to interactions with natural organic matter, we hypothesize that pharmaceutical sorption to soils and sediments is governed by 3 mechanisms: (1) electrostatic attraction to oppositely charged sites on mineral surfaces; (2) cation exchange reactions with aluminosilicate clay minerals, and (3) surface complexation to iron and aluminum oxides. The ultimate goal of the proposed research is to quantitatively describe sorption of pharmaceuticals to clay and oxide soil minerals based on a mechanistic understanding of sorption phenomena.Methods: The research goal will be achieved by investigating pharmaceutical sorption to modelsorbents so that with sorbent phases present in real soil or sediment samples can be probedindependently. Five model sorbents will be used: 2- and 3-layer clays (kaolinite and montmorillonite), and iron and aluminum oxides. The high-use veterinary antibiotics oxytetracycline, ciprofloxacin, and FCQA and Enro-CO2 (substructures of ciprofloxacin) will be employed as test sorbates because agricultural antibiotic use represents the most concentrated pharmaceutical release to the environment.Results from this research can be used to predict pharmaceutical sorption from compound properties (solution complexation constant) and sorbent characteristics (surface chemistry at given pH/ionic strength).Significance and Benefits of Research: The proposed research will provide the first mechanistic model of solid-water partitioning of important veterinary antibiotic compounds. The quantitative models developed for high-purity sorbents can be adapted to develop a general partitioning model for any soil or sediment phase. Accurate descriptions of soil- and sediment-water partitioning will help to interpret observed pharmaceutical distributions in field surveys of ambient concentrations of pharmaceutical compounds, including our test sorbates, in surface and groundwater (USGS Toxic Substances Hydrology Program). Ultimately, the quantitative model of pharmaceutical sorption developed here can be used inan environmental fate model that, coupled with a toxicology model, will enable accurate assessments of the risk posed by the release of veterinary pharmaceuticals to aquatic environments.Educational Benefits: Integration of undergraduate students into research activities will provide an opportunity for these students to work closely with faculty to solve open-ended research problems. The proposed research will also form a foundation for future integrated research activities between Environmental, Pharmacy, and Agricultural programs at UConn and Duke.