Modeling the upper ocean dynamics in the Subantarctic and Polar Frontal Zones in the Australian sector of the Southern Ocean,
Description
A one-dimensional (1-D) mixed layer model (the Chen scheme) was applied in the Subantarctic Zone (SAZ) and the Polar Frontal Zone (PFZ) to simulate the upper ocean dynamics. The model was forced with 4 years data of the heat fluxes, freshwater fluxes, and wind stresses from the National Centers for Environmental Prediction. In both the SAZ and PFZ, the 1-D model was capable of reproducing the amplitude of the seasonal sea surface temperature (SST) and the seasonality of the mixed layer depth (MLD). The shallowest MLD was found in January-February (20 m in the SAZ, 35 m in the PFZ), and the deepest MLD was found between August and October (600 m in the SAZ, 160 m in the PFZ). The summer MLD was shallower in the SAZ than in the PFZ due to the lower wind stress. However, the shallower winter MLD in the PFZ than in the SAZ was due to the strong stratification in the water below the mixed layer. In the SAZ, variability in the wind stress was the dominant term driving the fluctuation in MLD in the summer, but variability in the heat flux was the major factor controlling the timing of the deepening and shoaling of the mixed layer in the winter. In the PFZ both the variability in the wind stress and the heat flux dominated the variability of the MLD in both the summer and the winter. Copyright 2001 by the American Geophysical Union., Cited By (since 1996):8, , , Downloaded from: http://onlinelibrary.wiley.com/doi/10.1029/2000JC000357/pdf (9 June 2014).
Sediment-water exchange of total mercury and monomethyl mercury in the San Francisco Bay-Delta,
Description
Five field trips were conducted in the San Francisco Bay-Delta between May 2000 and October 2001 to investigate the sediment-water exchange of total mercury (Hg) and monomethyl mercury (MMHg). Solid-phase Hg averaged ∼1 nmol g -1 and did not show any variability with depth or time or among sites. In contrast, solid-phase MMHg showed considerable vertical, temporal, and spatial variability (0.4-66 pmol g -1), with the highest values occurring at a peat-rich environment in May 2001, suggesting that MMHg production was largely controlled by temporal factors and habitat type. In pore water, both Hg and MMHg concentrations were generally elevated near the sediment-water interface during warm months. Sediment-water exchange flux of MMHg, determined with benthic chamber deployments, ranged from -92 to 850 pmol m -2 d -1, with higher values occurring in May. In most cases, diffusional fluxes of Hg and MMHg, estimated with the use of interfacial concentration gradients, constituted only a minor portion of the measured fluxes, suggesting the importance of advective processes on sediment-water exchange. Surface-water transect and time series studies conducted in Franks Tract support the commonly held belief that wetland and marsh regions are major sources for MMHg within the Delta. The integrated sediment-water fluxes of Hg and MMHg in the study area were estimated to be 130 and 6 mmol d -1, respectively, and the benthic input was as important a source of Hg and MMHg as the riverine input within the Delta during low-flow months., Cited By (since 1996):63, Rocks and Cores,
Oceanography, CODEN: LIOCA, ,
