INFLUENCE OF HYDROPHYTIC VEGETATION ON BIOGEOCHEMICAL PROCESSES WITHIN CONTAMINATED WETLAND SYSTEMS

Abstract

The body of research contained within this dissertation serves to shed light onto the influence hydrophyte communities exhibit on biogeochemical processes and subsequently on metal mobility within wetland systems. The focus of the first thesis is centered on the role macrophytes play in enhancing the sequestrative processes for contaminates within constructed wetlands receiving nonpoint source pollution. Vegetated and unvegetated plugflow microcosms were constructed and operated such that an enhanced understanding of the governing redox process and newly observed diurnal biogeochemical process manipulation was uncovered. These findings are directly applicable to newly published stormwater regulations and thus provide direct benefit to the larger body of knowledge relating to stormwater management requirements. In an effort to better understand seasonal and hydrologic variability, and the associated impact on redox governing processes within the rhizosphere environment, a new semi-permanent dialysis porewater sampler was designed, constructed and field tested with positive results validated by extensive seasonal data. These new samplers, and the information gleaned in support of the associated theses, allow for an enhanced understanding of the biogeochemical processes within the rhizosphere as well observe the impacts of redox shaping controls on metal mobility within wetland systems. A duel pronged approach was completed with enhanced sampler deployments within natural and constructed wetland systems. Experimental sequence captured monthly data sets, inclusive of iron, sulfur, lead, arsenic, chromium and organic carbon, over one full season for three separate locations. Lastly, a robust experimental wetland system was constructed and operated under varying hydrologic conditions uncovering not only details pertaining to the reductive interaction of iron, sulfur and chromium within but highlighting the sequestrative potential an enhanced wetland system can provide in managing contaminates within the rhizosphere.