Development & application of methods to determine bioavailability

环境基质中污染物的总浓度不能预测对生态或公共卫生造成不利影响的可能性。环境中引入的污染物经历了各种反应，从而降低了它们的活性，从而降低了它们对目标生物的生物利用度。这些反应包括吸附在颗粒上或进入颗粒中，与碎屑有机物质络合，或以不溶性络合物的形式沉淀。从决策的角度来看，需要的是能够确定样本中污染物的比例，以便将其分配到目标受体中。要真正估计污染物对特定生态系统的影响，这显然是必要的。目前检查生物利用度的技术包括在实验室环境中进行严格的分析分离。这些方法可能很耗时，而且可能会受到采样和分析过程中通过改变采样条件而引入的人工制品的影响。这项提议的目标是开发和实地测试采样设备，以确定水生沉积物中金属和有机污染物的自由活度(而不是总浓度)。采样器的基本前提是引入对目标污染物具有已知热力学亲和力的固体或液体底物。污染物分配到底物的程度可以用来确定污染物在原始样品中的活性。这些取样器可用于进一步检测控制活性和原始样品的特定环境因素。这些采样器可以用来进一步检查特定的环境因素，这些因素控制着环境中污染物的活性和生物有效性。将使用半透膜装置(SPMD)在实验室和现场条件下检测沉积多环芳烃的生物有效性。需要检验的主要假设是，碳氢化合物燃烧产生的碳烟相碳(以及总有机碳)的存在将改变多环芳烃的分配，使得燃烧来源的多环芳烃的热源混合物的生物可利用性低于类似浓度的石油泄漏产生的多环芳烃混合物。对于金属污染物，将构建一块固定了8-羟基喹啉的硅胶板，对游离金属离子进行采样，以检验金属离子的自由离子浓度与硫化物和总有机碳浓度的关系。

The total concentration of contaminants in an environmental matrix is not predictive of the potential for adverse ecological or public health effects. Contaminants introduced in the environment undergo a variety of reactions that reduce their activity and thus their bioavailability to target organisms. These reactions include sorption onto or into particles, complexation with detrital organic matter, or precipitation as insoluble complexes. What is needed from a decision making standpoint is an ability to determine the fraction of contaminants in a sample available for partitioning into target receptors. This is obviously necessary to truly estimate the effects contaminants will have a given ecosystem. Current techniques to examine bioavailability involve rigorous analytical separations in a laboratory setting. These methods can be time consuming, and potentially suffer from artifacts introduced through alteration of sample conditions during sampling and analysis. The goal of this proposal is to develop and field test sampling devices that determine the free activity (as opposed to the total concentration) of metal and organic contaminants in the aquatic sediments. The basis premise of the samplers is to introduce a solid or liquid substrate with a known thermodynamic affinity for a contaminant of interest. The extent of contaminant partitioning to the substrate can be used to determine the contaminant's activity in the original sample. These samplers can be used to further examine specific environmental factors that control the activity and original sample. These samplers an be used to further examine specific environmental factors that control the activity and bioavailability of contaminants in the environment. Semipermeable membrane devices (SPMDs) will be used to examine the bioavailability of sedimentary PAHs under both laboratory and field conditions. The primary hypothesis to be tested is that the presence of soot phase carbon (in addition to total organic carbon) from hydrocarbon combustion will alter the partitioning of PAHs such that a pyrogenic mixture of PAH's from combustion sources will be less bioavailable than a similar concentration of a petrogenic mixture of PAH's arising from oil spills. For metal contaminants, a silica plate with immobilized 8-Hydroxyquinoline that samples free metal ions will be constructed to test the hypothesis that the free ion concentration of metal concentrations from the sulfide and total organic carbon concentrations.