Aquatic Toxicity of Carbon-Based Nanomaterials at Sediment-Water Interfaces
|Principal Investigator||Baolin Deng|
|Relevance to Implications||High|
|Class of Nanomaterial||Engineered Nanomaterials|
|Broad Research Categories||
|Anticipated Total Funding||$399,506.00|
|Anticipated End Year||2010|
Objectives of the study are to investigate toxicity of carbon-based one-dimensional (1-D) nanomaterials toward aquatic organisms that inhabit sediment-water interfaces and to identify factors controlling the toxicity to sediment-dwelling organisms. Because of their extraordinary properties, carbon nanotubes, nanofibers, and silicon carbide nanowires may find wide applications as catalyst supports, hydrogen storage devices, electrodes and sensors, reinforcing fibers, insulating materials, and flat panel display, etc. These nanomaterials often contain heavy metals (e.g., Fe, Co, Ni, Cu, and Cr), mostly introduced as catalysts for their manufacturing. There is little doubt that some of these manufactured nanomaterials will be released into the environment. Our knowledge on their environmental impact, however, is extremely limited. We hypothesize that the aquatic toxicity of metal-containing carbon-based nanomaterials is contributable to three aspects: (i) soluble metals released from metal-loaded nanomaterials; (ii) toxicity due to metal-free nanomaterials; and (iii) metals bound to the nanomaterials. This project will test these hypotheses with a goal of elucidating whether the interaction between heavy metals and carbon-based nanomaterials will neutralize or promote the aquatic toxicity or have no effect.
Involves preparing 1-D nanomaterials for toxicity testing with aquatic organisms inhabiting sediment-water interfaces. Specific tasks include:
A. Selection and preparation of carbon-based nanomaterials with defined heavy metal contents. Primary focus will be on carbon nanotubes and SiC nanowires with defined heavy metal contents. Multi gram quantities of nanomaterials with controlled microstructure, composition, and metal concentration will be prepared primarily at the University of Missouri-Columbia. Some carbon nanotubes will also be acquired from commercial sources.
B. Toxicity tests at sediment-water interfaces with amphipods (Hyalella azteca), midge (Chironomus dilutus), and early life stages of freshwater mussels. Since carbon nanotubes and fibers are highly hydrophobic, the materials may predominantly accumulate at the sediment-water interface when released into the aquatic system. Thus, toxicity testing with these sensitive sediment-dwelling organisms is particularly important and will be conducted.
C. Identification of factors controlling the toxicity towards the sediment-dwelling organisms. The major components causing the toxicity, whether these are soluble heavy metals released from the carbon based nanomaterials, metal-free carbon based nanomaterials, or carbon-based nanomaterials with bound metals, will be identified by comparison with control experiments and by monitoring heavy metal concentrations in the testing solutions.
It is expected that through this project, we will significantly improve our understanding of the aquatic toxicity of carbon-based 1-D nanomaterials impregnated with heavy metals. Specifically, the project will: (i) generate toxicity data on effects of pure carbon nanomaterials on sediment-dwelling organisms, including amphipods, midge, and juvenile freshwater mussels; and (ii) show whether heavy metals imbedded in the nanomaterials will alter the aquatic toxicity of the nanomaterials, thus contribute to the general conceptual understanding of toxicity of nanomaterials. Such understanding is critically needed for the regulatory agency to make policy decisions that will protect the environment and human health while at the same time without undue burden for the technological development. The project will also provide opportunities to train graduate students in an interdisciplinary research environment involving aquatic toxicology and environmental chemistry and engineering, contributing to the Nations future workforce development in science and engineering.