Human implications of contaminant cycling in urban soils
Human connection to soil and plants is important, no less in cities than in rural and so-called wilderness areas. But in cities and other areas with industrial legacies this contact can inadvertently expose people to harmful chemicals. We work to keep increase people’s safety while they grow food, relax and play outside. We determine how toxic chemicals are, how they behave in soil, and how they are taken up into plants and people. We collaborate with community groups to bring science to support their priorities, develop accessible, sustainable soil remediation solutions, and work with agencies to develop guidance on how people can grow healthy food more safely.
Characterizing ocean nanoparticles that export iron from seafloor to surface
Iron (Fe), a required micronutrient for phytoplankton, limits carbon fixation in 1/3 of the global ocean. Recently, iron emitted from deep-sea hydrothermal vents was shown to reach surface waters. The physical, chemical, and biological processes leading to transport of hydrothermally derived iron to the photic zone have been investigated for few vents sites globally, remain poorly understood, and appear to depend on local conditions. To better understand the range of processes and conditions leading to export of iron from hydrothermal systems, we characterize iron speciation in hydrothermally derived particles from vent fields including the Juan de Fuca Ridge, the Southern East Pacific Rise, and the Rainbow Vent field (Mid Atlantic Ridge), using bulk and microprobe X-ray absorption spectroscopy and diffraction. This research helps constrain global iron cycle and carbon sequestration models.
Nanoparticles as biogeochemical tracers of life-conducive conditions on icy ocean moons
On Earth, hydrothermal plume particles have long transport distances and have been shown to reach surface waters. Via comparative oceanography we anticipate that if particles also form in hydrothermal plumes on icy ocean moons like Jupiter’s Europa, they too could be transported to the surface waters and ejected onto the ice shell. We investigate how particle chemistry and morphology could be altered during transport from putative hydrothermal plumes to the ice shell surface of icy ocean moons. This is part of a broad habitability investigation searching for chemical environments, like sea floor hydrothermal plumes, that could be conducive to life. And since field work on icy ocean moons is a long way off (in more than one way), I explore anthropogenic ice caves in Minnesota!
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