Development & application of methods to determine bioavailability

环境基质中污染物的总浓度不能预测潜在的不利生态或公共健康影响。引入环境中的污染物经过各种反应，降低其活性，从而降低其对目标生物的生物利用度。这些反应包括吸附在颗粒上或颗粒内，与碎屑有机质络合，或作为不溶性络合物沉淀。从决策的角度来看，需要的是确定样品中可划分为目标受体的污染物比例的能力。这对于真正估计污染物对给定生态系统的影响显然是必要的。目前检验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。这些方法可能是耗时的，并且可能受到采样和分析过程中通过改变样品条件而引入的伪影的影响。本提案的目标是开发和现场测试取样装置，以确定水生沉积物中金属和有机污染物的自由活性（而不是总浓度）。取样器的基本前提是引入固体或液体底物，对感兴趣的污染物具有已知的热力学亲和力。污染物对底物的分配程度可用于确定污染物在原始样品中的活性。这些采样器可用于进一步检查控制活性和原始样品的特定环境因素。这些采样器可用于进一步检查控制环境中污染物活性和生物利用度的特定环境因素。半透膜装置（spmd）将用于在实验室和现场条件下检测沉积多环芳烃的生物利用度。要测试的主要假设是，碳氢化合物燃烧产生的烟灰相碳（除了总有机碳之外）的存在将改变多环芳烃的分配，这样，来自燃烧源的多环芳烃的热原混合物的生物可利用性将低于由石油泄漏产生的类似浓度的多环芳烃的成岩混合物。对于金属污染物，将构建一个固定8-羟基喹啉的二氧化硅板，该板将采样游离金属离子，以测试假设金属的游离离子浓度来自硫化物浓度和总有机碳浓度。

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.