Plastic marine debris or the plastisphere impacts marine organisms through ingestion, entanglement, and as a source of toxic chemicals. The plastisphere could also have a major impact on biogeochemical cycles in the oceans. Plastics are transported via major ocean currents to central gyres, where they reside for decadal time scales. The amount of plastic waste is large, exceeding 2 kg/ km2 in central gyres. Even the most recent ocean surveys cannot account for the amount of debris estimated to enter the ocean, with inputs and outputs differing by orders of magnitude.
The sustainability of human civilization and its evolving lifestyle depends fundamentally on a sustainable food and energy supply. This can largely be linked to the availability of reactive nitrogen (Nr), phosphorus (P) and trace-element nutrient availability for natural and managed ecosystems. Nr, P and Fe are known to stimulate productivity while other elements, like Cu and Mn, can be toxic for ecosystems. Nr is also a critical link for the carbon cycle, and directly/indirectly impacts climate and human/ecosystem health.
Ocean dynamics constantly generates seismic and acoustic noise (e.g. vie wave-seafloor interaction, surface wave activities, ice-noise and anthropogenic sources). This ubiquitous ambient noise waves, which can be measured continuously with hydrophones and seismic stations, travel around the earth and can be used to monitor their generating sources and image the propagating medium. This project will characterize the spatial and temporal generation mechanism of seismic and acoustic ocean noise sources which can be used for passive remote sensing and monitoring purposes.
Advection and biological consumption are both important sinks for oil and gas released from natural seeps in the Gulf of Mexico. We will use a combination of stable isotope measurements and high resolution modeling with both passive and positively buoyant tracers to study the interaction between physical and biological processes in distributing and transporting the carbon released from natural seeps. We will focus on three major seep fields in the Northern Gulf with different water depths –GC185 (ca. 400 m), GC600 (ca. 1200 m), and GC767 (ca.