Knowledge of the partitioning of actinides to sediments in natural systems is essential for modeling their environmental fate. Using two different sequential extraction methods, we have studied the partitioning of U and Pu to an acidic, sandy lake sediment that was contaminated due to nuclear production activities. We find that both methods yield similar partitioning information, and that much of the U is associated with insoluble phases, whereas the majority of the Pu is extracted with oxidizable phases, defined to be predominantly organic matter. Our study suggests that U in this ecosystem is of natural origin. Although Pu and Fe in this system are known to cycle from the sediments to the water column during periods of anoxia, only a low percentage of Pu is extracted from the phases that are reducible, which are operationally defined as amorphous Fe oxides. Although this sediment is low in organic matter, our results suggest that natural organics dominate the partitioning of Pu in this system.

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The use of two-dimensional gel electrophoresis for differential analysis in proteomics was revolutionized by the introduction of 2-D fluorescence difference gel electrophoresis (2-D DIGE). This fluorescence-based technique allows the use of multiplexed samples and an internal standard that virtually eliminates gel-to-gel variability, resulting in increased confidence that differences found between samples are due to real induced changes, rather than inherent biological variation or experimental variability. 2-D DIGE has quickly become the "gold standard" for gel-based proteomics for studying tissues, as well as cell culture and bodily fluids such as serum or plasma. This chapter will describe the basic 2-D DIGE technique using minimal labeling, image acquisition using high-quality fluorescence scanners, and software capable of analyzing the multiplexed images and normalizing the data using the internal standard.