Pharmaceutical Sorption to Model Soil Components

0225696麦凯人类和兽药化合物在许多环境介质中越来越多地被检测到，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环境中不断增加的这些生物活性化合物的暴露。引起关注的健康影响包括抗生素耐药性的传播、内分泌干扰活动和非靶标生物的不良反应。假设和目标：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是由三种机制控制的：(1)对矿物表面相反电荷位置的静电吸引；(2)与铝硅酸盐粘土矿物的阳离子交换反应；(3)表面对铁和铝氧化物的络合作用。这项研究的最终目标是基于对吸附现象的机理理解，定量描述药物在粘土和氧化土壤矿物上的吸附。方法：通过研究药物对吸附剂的吸附来实现研究目标，以便能够根据真实土壤或沉积物样品中存在的吸附剂相来进行研究。将使用五种模型吸附剂：两层和三层粘土(高岭石和蒙脱石)，以及铁和铝氧化物。常用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)将被用作测试吸着剂，因为农业抗生素的使用代表了对环境最集中的药物释放。本研究结果可用于根据化合物性质(溶液络合常数)和吸附特性(给定pH/离子强度下的表面化学)来预测药物的吸附。研究的意义和效益：本研究将提供第一个重要兽用抗生素化合物固-水分配的机理模型。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相的通用分配模型。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(包括我们的试验吸附物)环境浓度的现场调查中观察到的药物分布(USGS有毒物质水文计划)。最终，这里开发的药物吸附的定量模型可以用于环境命运模型，再加上毒理学模型，将能够准确地评估兽药释放到水环境中所构成的风险。教育好处：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的机会，以解决开放式研究问题。这项拟议的研究还将为未来康涅狄格州大学和杜克大学环境、药学和农业项目之间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.