Microbial controls of hydrophobic organic chemical bioavailability in sediments

沉积物中疏水性有机化学生物利用度的微生物控制

• 批准号: RGPIN-2022-03531
• 负责人: Drouillard, Ken
• 金额: $ 2.4万
• 依托单位: University of Windsor
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=755159
• 关键词: Microbial; controls; hydrophobic; organic; chemical

This research will demonstrate linkages between microbial function of sediment organic matter processing and hydrophobic organic chemical (HOC) bioavailability. Bioavailability is a subfield of ecotoxicology concerned with measuring the fraction of total chemical present in an environmental media (e.g. sediments) that can be taken up and contribute to chemical exposures in organisms. This research focuses on HOCs represented by legacy pollutants such as polychlorinated biphenyls (PCBs) that were widely used in industrial processes, are globally dispersed, yet continue to contribute to bioaccumulation and biomagnification in fish leading to human health concerns about the consumption of contaminated fish. To date, most research on chemical bioavailability of HOCs in sediments focusses on chemical sorption to abiotic (non-living) components of the sediment including detrital organic carbon and highly modified carbons such as black carbon. However, microbial biomass itself contributes to the total sediment organic carbon commonly measured in conventional techniques. In addition, microbial activity mediates the transformation of settled particulate and dissolved organic material incorporated into sediments. These transformations alter the sorptive capacity of settled carbon that is hypothesized to change HOC bioavailability in two ways: 1) by increasing the HOC concentrations in porewater when labile carbon is rapidly mineralized and/or 2) by microbial biomass and labile carbon being consumed by benthic invertebrates resulting in biomagnification. Objectives 1-2 will demonstrate that porewater chemistry of HOCs is altered in sterilized vs non-sterilized sediments following addition of fresh carbon to prime the system and that changes to porewater HOC chemistry translate to differences in invertebrate HOC bioaccumulation. Advanced techniques to determine abiotic and microbial phase distribution of HOCs will allow contrast of chemical activity in porewater and microbial biomass to test the above hypotheses. Objective 3 will examine HOC porewater concentrations and microbial community composition/function through depth in sediment cores from lakes that vary in productivity and redox to establish that HOC porewater concentrations are driven by transitions in microbial function and carbon processing rates, showcasing the utility of ecotoxicology tools to measure carbon mineralization necessary for lake wide carbon budgets. Objective 4 will demonstrate applied concepts, measuring differences in HOC bioavailability in sediments previously restored coupled with food web models to forecast how choice of mitigation method translates to lowering of fish HOC contamination. Benefits to Canada include improved bioaccumulation models to assess and guide contaminated sediment restoration and demonstration that multiple stressors (e.g. pollutant mixtures and climate change) act together to alter microbial function and decrease ecosystem capacity for toxic pollutants.

本研究将展示微生物对沉积物有机质的处理功能与疏水有机化学品（HOC）的生物有效性之间的联系。生物利用度是生态毒理学的一个子领域，涉及测量环境介质（例如沉积物）中存在的化学品总量中可被吸收并导致生物体接触化学品的部分。本研究的重点是以多氯联苯（PCB）等遗留污染物为代表的HOCs，这些污染物广泛用于工业流程，分布在全球各地，但仍在继续促进鱼类的生物累积和生物放大，导致人们对食用受污染鱼类的健康问题表示担忧。迄今为止，大多数关于沉积物中HOCs的化学生物利用度的研究集中在沉积物的非生物（非生物）组分的化学吸附，包括碎屑有机碳和高度改性的碳，如黑碳。然而，微生物生物量本身对常规技术中通常测量的总沉积物有机碳有贡献。此外，微生物活动介导了沉降颗粒和溶解有机物质进入沉积物的转化。这些转换改变了吸附能力的固定碳，假设改变HOC生物利用度在两个方面：1）通过增加HOC浓度在孔隙水时，不稳定的碳迅速矿化和/或2）通过微生物生物量和不稳定的碳被消耗的底栖无脊椎动物导致生物放大。目标1-2将证明，在添加新鲜碳以启动系统后，在灭菌与非灭菌沉积物中HOC的孔隙水化学发生改变，并且孔隙水HOC化学的变化转化为无脊椎动物HOC生物累积的差异。先进的技术，以确定非生物和微生物相分布的HOCs将允许在孔隙水和微生物生物量的化学活性的对比，以测试上述假设。目标3将检查HOC孔隙水浓度和微生物群落组成/功能，通过深度在不同的生产力和氧化还原湖泊的沉积物岩心，建立HOC孔隙水浓度是由微生物功能和碳处理速率的转变，展示生态毒理学工具的效用，以测量碳矿化所需的湖泊范围内的碳预算。目标4将展示应用概念，测量之前恢复的沉积物中HOC生物利用度的差异，再加上食物网模型，以预测缓解方法的选择如何转化为降低鱼类HOC污染。对加拿大的惠益包括：改进生物累积模型，以评估和指导受污染沉积物的恢复，并证明多种压力因素（例如污染物混合物和气候变化）共同作用，改变微生物功能，降低生态系统对有毒污染物的能力。