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Geology topics

Steven J. Eisenreich

Publications and source records attributed to Steven J. Eisenreich.

5 recordsLinked to original sources
USGS2002

Application of headspace analysis to the study of sorption of hydrophobic organic chemicals to α-Al 2 O 3

The sorption of hydrophobic organic chemicals (HOCs) to ??-Al2O3 was investigated with a headspace analysis method. The semiautomated headspace analyzer gave rapid, precise, and accurate results for a homologous series alkylbenzenes even at low percentages of solute mass sorbed (3-50%). Sorption experiments carried out with benzene alone indicated weak interactions with well-characterized aluminum oxide, and a solids concentration effect was observed. When the sorption coefficients for benzene alone obtained by headspace analysis were extrapolated up to the solids concentrations typically used in batch sorption experiments, the measured sorption coefficients agreed with reported sorption coefficients for HOCs and sediments of low fractional organic carbon content. Sorbed concentrations increased exponentially with aqueous concentration in isotherms with mixtures of alkylbenzenes, indicating solute-solute interactions at the mineral surface. Sorption was, however, greater than predicted for partitioning of a solute between its pure liquid phase and water, indicating additional influences of the surface and/or the structured liquid near the mineral surface. ?? 1993 American Chemical Society.

Environmental Science & Technology↗
USGS2002

Accumulation and diagenesis of chlorinated hydrocarbons in lacustrine sediments

Two sediment cores were taken from the Rochester Basin of eastern Lake Ontario and analyzed for the radionuclides 210Pb and 137Cs and several high molecular weight chlorinated hydrocarbons (CHs). The two sites are geographically proximate but differ in sedimentation rate, permitting sedimentation-dependent processes to be factored out. The 210Pb chronology showed a mixed depth of 3-5 cm and an intrinsic time resolution of 11-14 years. Vertically integrated numbers of deposit-feeding oligochaete worms and burrowing organisms are insufficient to homogenize the sediment on the time scale of CH inputs, which are non steady state. U.S. production and sales of polychlorinated biphenyls (PCBs), DDT, Mirex, and hexachlorobenzene (HCB), as determinants of the shape of the input function, adequately predict the overall shape and, in many cases, details in the sedimentary profile. Sediment focusing factors (FF) inferred from 137Cs and 210Pb inventories averaged 1.17 and 1.74 for cores E-30 and G-32, respectively. This permitted CH accumulation rates to be corrected for focusing. Apparent molecular diffusion coefficients modeled for many of the CHs were about (1-3) ?? 10-9 cm2/s.

Environmental Science and Technology↗
USGS1999

Nearshore versus offshore copper loading in Lake Superior sediments: Implications for transport and cycling

A thorough understanding of the fate and transport of metals in Lake Superior is necessary in order to predict the ability of Lake Superior to recover from anthropogenic perturbations (copper mining). Sediment cores were collected from nearshore and offshore sites in Lake Superior and used to evaluate spatial and temporal variations in copper loading associated with mining-related activities. Although both settings have been strongly affected by anthropogenic releases of copper, copper concentrations in nearshore cores are significantly greater than those found in offshore cores, implying that nearshore copper loading is dominated by simple deposition and burial of sediment generated from mining activities. Temporal variations in copper profiles in sediments from nearshore environments closelymimic copper production rates. Conversely, copper loading histories derived from offshore sediments are not well correlated to production rates. The offshore sediment cores, when compared with analogous cores from Lakes Ontario and Michigan, show that the average, lake-wide intensity of copper loading in Lake Superior is comparable to the other two lakes, despite the fact that Lake Superior has received the largest total burden of anthropogenic copper. Cu/Zn ratios, used to evaluate the amount of copper loading derived from mining discharges, vary strongly in nearshore environments in response to loading. Cu/Zn ratios in offshore sediments are much less variable, implying that copper loading may be regulated by additional mechanisms (solution chemistry and/or biologic uptake). Study of trace metal partitioning within Lake Superior sediments indicates that the organic fraction of the sediment contains the majority of the copper. Copper concentrations in offshore sediments are significantly correlated to organic carbon content of the sediment whereas copper concentrations in nearshore sediments are not. These findings support the model that transport and deposition of particles released from mining discharges dominate copper loading in nearshore sediments, whereas biologic uptake and settling of particulate organic matter may regulate copper loading in offshore sediments.

Journal of Great Lakes Research↗