Neil Fitzgerald (CHEM) - Development of methods for low-level measurements of cadmium in environmental samples from the Hudson River.
My interest in the project is to develop methods to treat and measure Cd levels in samples of water, sediment, plants, and aquatic species (such as zebra mussels) from the Hudson. Some methods (for example, Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and Ionically Coupled Atomic Emission Spectrometry (ICP-AES) with acid digestion) are well established, but may require further development to eliminate interferences in complex sample matrices. The method of Chemical Vapor Generation Atomic Absorption Spectrometry (CVGAAS) is capable of lower detection limits than ICP-AES and is faster, simpler, and cheaper than GFAAS. This technique was previously set up and optimized, but suffers from severe interference for complex samples. One area of investigation is to develop methods to overcome these interferences, for example by using masking agents, standard additions calibration or a prototype sample introduction system. The ultimate aim is to develop a sensitive, reliable method to monitor Cd levels in water, sediment, and biological samples.
Zofia Gagnon (ENV SCI) - Physiological and toxicological effects of cadmium in plants.
There is a significant body of information on the effect of Cd on experimental animals extrapolated to human health, but a lack of information on the bioavailablity, bioaccumulation and toxicological effect of Cd on plants as a primary element of the food chain. Physiological and toxicological effects of Cd will be studied using two vastly different types of plants as models: 1) a wild wetland species such as common Sphagnum moss that has the ability to accumulate metals, or (2) a commonly grown home garden and agricultural species (tomato). Toxicological effects will be assessed by measuring plant growth (biomass, height) and physiological factors (chlorophyll content). The effect of Cd on DNA will be assessed with the alkaline single cell gel electrophoresis assay. The accumulation of Cd in plant tissues will be determined using atomic absorption. The mechanism of tolerance to Cd will be also studied.
John Galbraith (CHEM) - Computational modeling of transition metal complexes.
In general, my research focuses on the how and the why of chemical bonding on the molecular level. For this project, that means determining the nature of the chemical interaction of Cd with systems representative of those found in the Hudson River. Rigorous solutions to the molecular Schrödinger equation are only possible for small molecules. Therefore, a thorough description of Cd binding from a molecular orbital or valence bond perspective will require modeling real Cd complexes by the Cd center and a minimum number of neighboring atoms. Force field methods can be used on a much larger scale, although many of the details are lost in the approximation. While computational modeling techniques are based on high-level mathematics and intricate theory, students do not need this background in order to effectively use commercial programs such as GAUSSIAN and HYPERCHEM.
Ray Kepner (BIOL) - Effects of cadmium on Hudson River microbes.
The vast majority of living matter in the Hudson is in the form of bacteria. Students working with Dr. Kepner will use chemical and microbiological methods to address specific hypotheses including: (a) river microbes concentrate Cd from the surrounding environment, and (b) exposure of microbes to Cd may stimulate release of infective viruses (prophage excision) as has been shown to be the case for Cu. Students will examine the role of specific Cd concentrations on microbial populations. At sites where organisms are collected, students will measure water quality using water test kits and a HydroLab DataSonde, but nearly all work will be done in the laboratory. Students will identify microbes using taxonomic guides and differential interference contrast microscopy. Bacteria will be identified with a Biolog MicroStation® system. Total and metabolically active bacteria will be counted with epifluorescence microscopy, which also will be used to examine viruses in natural samples and from cultures exposed to Cd. Isolated algal, bacterial, and cyanobacterial taxa will be assayed for metal effects using a rapid microplate assay to yield data about the influence of Cd on microbial growth.
Tom Lynch (ENV SCI)– Chemica factors affecting zebra mussel population density in the Hudson.
Zebra mussel (Dreissena polymorpha) population densities in the Hudson near Marist vary considerably from year to year, whereas upstream populations tend to exhibit higher and more stable population densities. Zebra mussels produce large numbers of planktonic larvae known as veligers by which they spread downstream from the sessile adults. Despite their continuous presence in the water column, the veligers often fail to show any significant colonization of vacant suitable hard substrates. One hypothesis for the varying population densities is the presence of chemicals known to be toxic to the mussels. These include cadmium, chlorine, and organotin compounds. Chlorine is widely used in the local area by a number of water treatment and wastewater treatment plants that discharge large quantities of chlorinated waste during the warmer months of the year into the year. Organotins are widely used in the production of antifouling paints used on boat hulls and other underwater structures. There are a number of marinas in the area. There is a long history of Cd contamination in the Hudson River. Students will select one of these chemicals and determine the spatial and temporal variations in their concentrations in water, bottom sediment, and zebra mussels at selected sites in the Hudson. Simple toxicity tests involving the selected chemical could also be conducted on the veligers.
Andrew Ryder (BIOL) - Development of a cyanobacterium capable of removing cadmium from contaminated river ecosystems.
Our goal is to create one or more strains of cyanobacteria capable of detecting elevated Cd concentrations in river water and responding by “turning on” genes that will specifically bind this heavy metal contaminant. The mouse MT-1 gene* and the Synechococcus smtA gene encode metallothioneins, which bind divalent cations including Zn2+, Cu2+, and Cd2+. Our immediate goal is to engineer these genes so that their products, the metallothionein proteins, preferentially bind Cd ions. I predict that cyanobacteria that carry these engineered genes will be more viable in waters contaminated with Cd than native organisms, and thus will be able to remediate these ecosystems. Project work will involve culturing cyanobacteria and Escherichia coli and the use of standard techniques of molecular biology including site directed mutagenesis and bacterial transformation. Additionally, we will work with Dr. Woolridge to purify the metallothionein proteins and Dr. Fitzgerald to measure the efficiency of the engineered proteins and microorganisms to remove Cd from liquid cultures.
Elisa Woolridge (CHEM) - Impact of heavy metal ions on microbial PCB degradation.
This research aims to determine the relationship between polychlorinated biphenyls (PCBs) biodegradation and heavy metal concentrations in Hudson River sediments. While both are recognized environmental toxins, the occurrence of ions such as Cd (II) may actually boost PCBs remediation by natural microorganisms. Our ultimate is to establish an in situ relationship; research will focus first, though, on the degradation of chlorinated aromatics by representative aerobic microorganisms with and without selected heavy metal ions. Specifically, the ability of selected bacterial and white rot fungal strains to mineralize PCBs with and without Cd (II) and Hg (II) ions will be evaluated; selected chlorinated hydroxybiphenyls will be used as PCB models. Products will be analyzed via gas chroma-tography and mass spectroscopy. For those organisms exhibiting significant remediation of the chlorinated aromatics, the correlation will be examined between the transformations and, presumably, the presence of oxidative enzyme activities, such as oxygenases, dioxygenases, peroxidases, and/or laccases. If the results of the in vitro analysis demonstrate a positive correlation between PCB reme-diation and heavy metal ion concentration, then River water and sediment samples from various zones of known contamination will be collected and assessed, and the indigenous aerobic micro-organisms cultivated. The oxidative enzyme systems of the isolated organisms, both in and out of culture, will be examined for their ability to degrade chlorinated aromatics in the presence of Cd (II) and Hg (II) ions.
