Seabed cores to a sediment depth of 24 cm were obtained by divers from an anoxic basin in the Pettaquamscutt estuary. The cores were processed to determine the age, viability, and vertical distribution of zooplankton resting eggs in the bottom sediments. Zooplankton eggs were found throughout the upper 24 cm. Copepod nauplii emerged from sediments as deep as 22 cm that were incubated in the laboratory. Based on 210Pb analyses of the sediments, we calculated that the viable eggs ranged in age from <1 yr in the surface layers of the seabed to >40 yr in the deepest portions. These data provide conclusive evidence for the existence of an egg bank.

Determination of sedimentary fluxes of 222Rn via diffusion was required as an input for a mass balance model of radon in a freshwater lake. We obtained these fluxes by: (1) direct measurement in the laboratory using a simulated sediment bed and water column; (2) a "sediment equilibration" technique; and (3) porewater modeling. The first method, analogous to an in situ benthic chamber approach, uses direct observation of the increasing 222Rn activity in water overlying a sediment bed packed in plastic columns. This allows one to directly measure the fluxes and determine the effective wet bulk sediment diffusion coefficient (Ds). Radon flux estimates using these three techniques agreed to within approximately 10 15%.Introductionw + diffusion coefficient,

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Environmental exposure to heavy metals is a potentially modifiable risk factor for preeclampsia (PE). Toxicologically, there are known interactions between the toxic metal cadmium (Cd) and essential metals such as selenium (Se) and zinc (Zn), as these metals can protect against the toxicity of Cd. As they relate to preeclampsia, the interaction between Cd and these essential metals is unknown. The aims of the present study were to measure placental levels of Cd, Se, and Zn in a cohort of 172 pregnant women from across the southeast US and to examine associations of metals levels with the odds of PE in a nested case-control design. Logistic regressions were performed to assess odds ratios (OR) for PE with exposure to Cd controlling for confounders, as well as interactive models with Se or Zn. The mean placental Cd level was 3.6 ng/g, ranging from 0.52 to 14.5 ng/g. There was an increased odds ratio for PE in relationship to placental levels of Cd (OR = 1.5; 95% CI: 1.1–2.2). The Cd-associated OR for PE increased when analyzed in relationship to lower placental Se levels (OR = 2.0; 95% CI: 1.1–3.5) and decreased with higher placental Se levels (OR = 0.98; 95% CI: 0.5–1.9). Similarly, under conditions of lower placental Zn, the Cd-associated OR for PE was elevated (OR = 1.8; 95% CI: 0.8–3.9), whereas with higher placental Zn it was reduced (OR = 1.3; 95% CI: 0.8–2.0). Data from this pilot study suggest that essential metals may play an important role in reducing the odds of Cd-associated preeclampsia and that replication in a larger cohort is warranted.