Estimation of Koc values for deuterated benzene, toluene, and ethylbenzene, and application to ground water contamination studies.

Sorption partition coefficients between water and organic carbon (Koc) for deuterated benzene, toluene, and ethylbenzene have been estimated by measuring values of the octanol-water partition coefficient (Kow) and HPLC retention factors (k1), which correlate closely to values of Koc. Measured values of log Kow for non-deuterated and deuterated toluene are 2.77 (+/- 0.02) and 2.78 (+/- 0.04), respectively, indicating that within experimental error, log Koc for deuterated and non-deuterated toluene are the same. The HPLC method provides greater precision, and yields values of delta log Koc (= log Koc [deuterated]-log Koc [non-deuterated]) of -0.021 (+/- 0.001) for benzene, -0.028 (+/- 0.002) for toluene, and -0.035 (+/- 0.003) for ethylbenzene. The small values of delta log Koc demonstrates that deuterated compounds are excellent tracers for the hydrologic behavior of ground water contaminants.

Aqueous complexing of nickel and zinc with 3-(N-morpholino)propanesulfonic acid and the solubility products of nickel and zinc hydroxides.

Phosphate and carbonate buffers serve as excellent pH buffers at circumneutral values of pH, except for systems requiring significant concentrations of heavy metals, which are severely restricted by the low solubilities of heavy metal phosphates and carbonates. 3-(N-morpholino)propanesulfonic acid (MOPS; pK(a) 7.2) is a suitable replacement buffer at circumneutral values of pH. However, only limited data are available concerning aqueous complexing involving MOPS. Aqueous complexing of nickel and zinc with MOPS has been investigated by the solubility method, using the sparingly soluble solids Ni(OH)(2) and Zn(OH)(2). Log K(sp) values of -15.9 and -16.6 have been determined for Ni(OH)(2) and Zn(OH)(2) respectively. Experiments with MOPS indicate that there is negligible complexing between Zn and MOPS, but that significant Ni-MOPS complexing occurs, such that Ni(2+) + OH(-) + MOPSNi(OH)MOPS composite function: log K = +7.0.

Magnesium-iron replacement in clay minerals in anoxic marine sediments.

In anoxic marine sediments iron is extracted from clay minerals to form a sulfide. Magnesium from the surrounding solution then replaces the extracted iron in the clay mineral structure. This process removes magnesium from seawater and serves as a control on the composition of interstitial waters in sediments.

Phase chemistry, structure, and radiation effects in lunar samples.

Phase chemistry, structure, and radiation effects were studied in rock, breccia, and soil samples. The regolith apparently developed in the final stages of accretion and was modified by later impact processes and radiation weathering. Exposure ages indicate transfer of buried igneous rock fragments to the near surface late in lunar history. With a few exceptions igneous rock fragments, soil, and breccia share the same distinctive chemistry, probably acquired before accretion of the moon. The igneous rocks texturally resemble basaltic achondrites, and the soil and breccias contain glassy spheres analogous to chondrules.