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Marine Sciences Division

Ultratrace Detection

Biomolecular Materials

Biomolecular Materials

Next-generation materials will include 3-dimensional nanosystems with multi-scale architectures constructed by bioassembly in genetically engineered living systems. The biosilica shells of diatoms, the frustules, are porous, hierarchically ordered structures with meso-to-nanoscale architecture, whose assembly can be genetically-modified for development of advanced materials for threat detection and other applications.

Through biosynthesis and bioassembly under ambient culture conditions, bioengineered diatoms can be made to produce biosilica frustules functionalized with proteins of interest. The functionalized frustules can be isolated in an active state and used in sensing and monitoring applications.

Because the mechanism for silica formation in diatoms is not well understood, the current research is focused on achieving a level of understanding that will enable improved construction of biosilica-immobilized functional proteins in bioengineered diatoms.

"Diatom biosensor could shine light on future nanomaterials." PNNL, March 22, 2012.

Geotraces — Mercury Intercalibration Study

Geotraces — Mercury Intercalibration Study

Mercury (Hg) is present at very low concentrations in the open ocean (low pM) and is subject to complex biogeochemical cycling. The major species of Hg found in the ocean are:

  • mercuric ion—Hg(II)
  • elemental Hg—Hg°
  • monomethylmercury—MMHg
  • dimethylmercury—DMHg

To understand this cycling, determination of the major species is necessary, but poses daunting analytical challenges. These forms can be volatile and photoactive, and their low concentrations make even small amounts of contamination ruinous. Despite these challenges, there are important benefits to studying Hg in the ocean, including increased understanding of the source and bioaccumulation dynamics of a toxic metal, the formation of organometallic compounds (including those of Ge, Se, Po, As) in the ocean, assessing the impact of an anthropogenically mobilized element, and the possible development of a paleoproductivity proxy.

To better understand Hg cycling, researchers at MSL are collaborating with Dr. Carl Lamborg (Woods Hole Oceanographic Institution), Dr. Robert Mason (University of Connecticut) and Dr. Chad Hammerschmidt (Wright State University) to conduct a comprehensive evaluation and laboratory comparison of the determination of Hg species in seawater. The study group will participate in two GEOTRACES Intercalibration cruises in the Atlantic and the Pacific. The Hg Intercalibration program is a critical first step prior to full fledged GEOTRACES cruise activities, so that the various investigators studying the chemical oceanography of Hg in the context of that project, which is intended to be decentralized and of such scope that no one laboratory would likely be capable of completing the whole effort, may compare their results.

The project consists of both a field component (participation in the two cruises) and shore-based component (refinement of analytical techniques, distribution of samples, and statistical examination of the data). In the laboratory, MSL will test new techniques for lowering the detection limit for MMHg in seawater, the cleanliness of bottles made from plastics other than Teflon, and the prospects of long-term storage of samples collected during the cruises for total and speciation measurements.

Ultratrace Chemistry

Ultratrace Chemistry

Advances in analytical chemistry and sample handling now permit the detection of select organic and inorganic contaminants at ultra-low levels (generally 10-100 times lower than in previous decades). This has permitted new applications for ultratrace chemistry in areas of chemical forensics and environmental assessments where precise measurements are needed for contaminant levels in different types of environmental media.

Researchers at MSL are applying ultratrace chemistry approaches to better understand the loading of contaminants in the marine environment. Many coastal regions have experienced near exponential growth over the past 50 years. A consequence of rapid urbanization is the greater atmospheric emissions of contaminants from both point (e.g. industrial and waste-water discharges) and non-point (auto emissions) sources of pollution.

In a recent project, MSL researchers estimated the atmospheric loading to the surface of Puget Sound for various contaminants such as polyaromatic hydrocarbons, polybrominated diphenyl ethers, polychlorinated biphenyls and metals such as aluminum, arsenic, cadmium, and copper. Researchers used specially designed ultra-clean passive samplers that were deployed at various urban and non-urban locations in the Puget Sound region. After several days, the samplers were retrieved and analyzed for contaminant levels. An important conclusion was less than 5% of the sediment bound contaminants was accounted for by atmospheric deposition. This suggests other sources of pollution are greater contributors to the contaminant load in Puget Sound.

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