Seminar

Bio-irrigation is defined as the solute exchange process between overlying water and pore water in sediments by burrow infauna, and is a part of bioturbation, which describes both biological particle reworking and bio-irrigation or burrow ventilation. Therefore, bio-irrigation can ultimately redistribute the microbial food supply and metabolic product, which may evidently alter the redox zonation in sediments.  A study of these processes may provoke and advance the understanding of coastal ecological effect influenced by submarine groundwater discharge (SGD), bio-irrigation, biogeochemical cycling, and microbial dynamics. Generally, bio-irrigation is determined by multiple factors, such as abundance and species of microbes and macro benthic animals, the depth at which they occur, and the sediment matrix they inhabit. Previous studies usually investigated bio-irrigation exchange rate and the associated influences on solute exchange flux through observation of pore water profiles, laboratory tracer experiments, and conceptualizing models parameterized and calibrated by the observed and laboratory results. However, bio-irrigation is mainly studied by one dimensional (1-D) models, but seldom by two/three-dimensional (2/3-D) models. Although some preliminary 2/3-D bio-irrigation models have been developed, these models rarely considered the influences of SGD and biogeochemical reaction transport. Therefore, it is of utmost importance to address the bio-irrigation processes via a fully coupled physical-chemical-biological 2/3-D model. Two representative field sites, where the dominant sediment is sand and mud respectively, will be used to conduct comparison experiments, and the obtained data from the experimental sites will be employed to parameterize and calibrate the models. The working flowchart will include field observatories, in-situ experiments, ex-situ incubation experiments, laboratory sample analysis, and numerical modeling. In the end, this study aims to quantify the bio-irrigation influences on hydrogeological and biogeochemical processes in coastal sediments and provide insights in coastal environmental and ecological management.