Development & application of methods to determine bioavailability

污染物在环境基质中的总浓度并不能预测其对生态或公众健康的潜在不利影响。引入环境的污染物会发生各种反应，降低其活性，从而降低其对目标生物的生物利用度。这些反应包括吸附到颗粒上或颗粒内，与碎屑有机物络合，或沉淀为不溶性络合物。从决策的角度来看，需要的是确定样品中可用于分配到靶受体中的污染物的分数的能力。这对于真正估计污染物对特定生态系统的影响显然是必要的。目前检查生物利用度的技术涉及实验室环境中严格的分析分离。这些方法可能是耗时的，并且可能遭受通过在采样和分析期间改变样品条件而引入的伪影。本提案的目标是开发和实地测试取样装置，以确定水生沉积物中金属和有机污染物的自由活度（相对于总浓度）。采样器的基本前提是引入对感兴趣的污染物具有已知热力学亲和力的固体或液体基质。污染物分配到基底的程度可用于确定原始样品中污染物的活性。这些采样器可用于进一步检查控制活动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。半渗透膜装置（SPMDs）将被用来检查沉积多环芳烃在实验室和现场条件下的生物有效性。要测试的主要假设是，碳氢化合物燃烧产生的烟灰相碳（除总有机碳外）的存在将改变多环芳烃的分配，使得燃烧源产生的多环芳烃的热解混合物的生物利用度低于漏油产生的多环芳烃的类似浓度的石油混合物。对于金属污染物，将构建具有固定化8-羟基喹啉的样品游离金属离子的二氧化硅板，以检验金属浓度来自硫化物和总有机碳浓度的游离离子浓度的假设。

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.