Properties of New York/New Jersey Harbor Sediments

Sediments found in waterways around the world may contain toxic compounds of anthropogeilic origin that can harm the environment and human health. As a result, it is often necessary to remove them and find disposal methods that are environmentally and economically acceptable. Here, we report on results obtained in an experimental program to characterize the nature of the sediment contamination. The objective was to gain a better understanding of the properties of the sediments to develop better methods for understanding the fate and transport of the contaminants and for improving methods for their removal from the sediments. Our investigations made use of x-ray facilities at the Brookhaven National Synchrotron Light Source (NSLS) and the European Synchrotron Radiation Facility (ESRF) at Grenoble, France. The experiments included: measurements of the microstructure of the sediments using computed microtomography, x-ray absorption, and fluorescence microscopy with resolutions as low as 0.2 micrometers to obtain information on the relationships of organic and mineral components of the sediments and on the distribution of contaminants on the surfaces of the sediment grains, investigation of functional groups of chemical compounds using x-ray absorption near-edge spectroscopy (XANES) and Fourier Transform Infrared Spectroscopy (FTIR). Scanning electron microscopy (SEM) and electron probe measurements were made to ascertain the morphology of the sediment surfaces and the distribution of metals on individual sediment grains

Differential interference contrast X-ray microscopy with twin zone plates at ESRF beamline ID21

We describe a novel approach for converting the specimens phase information into strong image contrast in the x-ray region, the differential interference contrast x-ray microscopy (X-DIC). In the used setup, X-DIC operation was accomplished by a twin zone plate (TZP), i.e. two zone plates on both sides of the same substrate, laterally shifted by about one outermost zone width. Once a TZP has been successfully produced by means of especially developed nanofabrication processes, it is as easy to use as a single zone plate, without any alignment difficulty or further requirements to the coherence of the illumination. The tremendeous contrast enhancement was demonstrated at the microscopy beamline ID21 at ESRF in Grenoble for test objects and biological samples. TZPs allow for full field X-DIC imaging as well as for DIC scanning transmission x-ray microscopy. The first experiments were camed out at 0.31 nm wave] ength (4 keV photon energy), and features down to approx. 60 nm could be resolved in X-DIC