Institute of Urban Environment,Chinese Academy of Sciences
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Dynamic variation of metal bioavailability and its responsive mechanisms of molecular biomarkers based on in-situ exposure

Proposal:Natural Scientific Foundation of China
Investigator:Zaosheng Wang
Abstract: Because of the complexity of physicochemical and geo-morphological characterization in heterogeneous sediments, the chemical speciation and mobility of metals at the sediment-water interface are in non steady state and even in dynamic conditions, which resulted in high variability of contaminant bioavailability. Based on traditional point sampling for chemical analyses alone, laboratory toxicity tests or field surveys of resident biota, sediment contamination characteristics and risk assessments had disadvantages of inaccuracy, scientifically representing a worst case scenario in terms of complex exposure dynamics and their internal limitations of these techniques. In this proposal, through powerful experimental designs and field-based manipulations of aquatic in situ exposure and the monitoring methods of kinetic DGT approach, relevant scientific issues were explored regarding sedimentary metals in polluted coast influenced by industrialization and urbanization. Understanding the degree of pollution and geochemical characteristics of the entire sediment matrix in the selected sampling sites, the devised in situ testing chambers were simultaneously exposed under field conditions in deployment sites combining the DGT and benthic organism clam Ruditapes philippinarum as the bioindicator species, the dynamic exchanges,translocation and mobilization of metals were then clarified among the ―particles, pore water, exposed organism‖ interface of sediments through measuring relevant dynamic parameters and resultant induced fluxes of metals during experimental procedures. Integrating the measurement of a wide battery of biomarkers based on the relevance of biological endpoint and our mechanistic knowledge, dynamic changing process of metal bioavailability in sediments were assessed, then their interactions with toxic effects were established between exposure and effects. Furthermore, variations of transcript expression of functuional genes in the choice of contaminant-specific biomarkers were obtained through high throughput oligo-DNA Microarray and quantitative reverse transcription polymerase chain reaction (Q-RT-PCR) in order to elucidate the mechanistic understanding of biological responses of cellular and molecular biomarkers. Simultaneously, the approach of in-situ evaluation combining the kinetic DGT is proposing to be established considering the consistency of framework as protocols among sediment chemistry, contaminant bioavailability and adverse effects, which provide a robust tool to support more comprehensive processes of sediment risk assessment, thus significantly improve accuracy and ecological relevancy in complex exposure situation when extrapolating the sediment quality guidelines (SQGs).

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