Seasonal changes in coccolithophore densities in the Southern California Bight during 1991–1992

Seasonal changes in coccolithophore cell densities in the San Pedro Basin, Southern California Bight, were investigated for the period October 1991 to September 1992. Coccolitho phore cell densities ranged from 6.3 × 10⁴ coccospheres per liter in March 1992 to 0 cells per liter in November 1991. High coccolithophore concentrations occurred in late winter and spring, and low densities occurred in the summer and fall. The high coccolithophore densities during spring 1992 were associated with unusually low surface nutrient concentrations and a lack of upwelling, suggesting that the high densities were not part of a typical spring phytoplankton bloom in this region. We propose that the suppression of upwelling during spring 1992 may have been related to the prevailing ENSO conditions. Emiliania huxleyi type A dominated the total coccolithophore population throughout the year, Umbilicosphaera sibogae var. sibogae being the second most important contributor to the coccolithophore assemblages.     

Heavy metal analyses in the marine environment - approaches to quality control

The validity of analyses of elements in the femto- and picomolar ranges in waters and sediments can be assessed on the basis of several criteria: an evaluation of the chemical technique; the use of primary standards and intercalibration exercises; and chemical and geochemical coherence of the results. Herein are reported analyses of ruthenium, platinum, palladium, rhenium, iridium and gold in oceanic samples. The gold concentrations in surface seawaters, at least 25 times less than those previously reported, are in accord with the concentrations of their periodic table neighbors as well as with crustal and sedimentary contents. The remarkable concentration of rhenium in seawater, in relation to its very low crustal abundance, can be explained by the inertness of the perrhenate ion.     

The biokinetic behavior of Tc in juvenile Coho Salmon, Oncorhynchus kisutch (Walbaum)

Juvenile coho salmon, Onchorynchus kisutch, were exposed to ^95mTc in both saltwater and freshwater to study the biokinetic behavior of this element in an anadromous fish. In freshwater, equilibrium whole-body concentration factors (CF₅) ranged from 28 to 32 in two separate experiments, in sharp contrast to an equilibriumCF of < 5 in saltwater. While the uptake kinetics were unimodal in saltwater, in freshwater, biomodal uptake kinetics were observed.Technetium-95m retention was biphasic in freshwater depuration experiments, an initial rapid loss of 21% to 26% of the steady-state activity with an elimination half-life of 3 to 5 days was followed by a slower loss rate, with a whole-body elimination half-life ranging from 23 to 33 days. In saltwater, retention was monophasic with an elimination half-life of 5–16 days. Dramatic decreases in ^95mTc body burdens when freshwater-labeled fish are transferred to Tc-labeled saltwater indicate that the changes in physiology accompanying saltwater acclimation lead to the loss of ^95mTc.     

Variability in concentration of suspensates in an estuarine environment

Three data sets of suspensate concentrations, collected under different sampling plans, were analyzed to develop a minimal sampling period, consistent with a predetermined precision. Individual samples collected during any part of a given day were within ±50% of the daily average. In the main channel of the estuary, a monthly sampling scheme closely approximated a weekly pattern; however, seasonal sampling was unsatisfactory. Outside the main channel, weekly, monthly, and seasonal sampling patterns did not differ greatly. Variability in suspensate concentrations must be considered when calculating sediment flux in estuarine and coastal waters.