Three-dimensional double-diffusive Marangoni convection in a cubic cavity with horizontal temperature and concentration gradients.

Three-dimensional double-diffusive Marangoni convection in a cubic cavity is studied in the present paper. Both the temperature and solute concentration gradients are applied horizontally. Direct numerical simulations are carried out for surface-tension Reynolds number 10≤Re≤500, surface-tension ratio -2≤R(σ)≤1, and Lewis number 1

Trace metal distribution in sediments of the Pearl River Estuary and the surrounding coastal area, South China.

Surface sediments and sediment cores collected at the Pearl River Estuary (PRE) and its surrounding coastal area were analysed for total metal concentrations, chemical partitioning, and Pb isotopic compositions. The distribution of Cu, Cr, Pb, and Zn demonstrated a typical diffusion pattern from the land to the direction of the sea. Two hotspots of trace metal contamination were located at the mixed zone between freshwater and marine waters. The enrichment of metals in the sediments could be attributed to the deposition of the dissolved and particulate trace metals in the water column at the estuarine area. The similar Pb isotopic signatures of the sediments at the PRE and its surrounding coastal area offered strong evidence that the PRE was a major source of trace metals to the adjacent coastal area. Slightly lower (206)Pb/(207)Pb ratios in the coastal sediments may indicate other inputs of Pb in addition to the PRE sources, including the inputs from Hong Kong and other parts of the region.

Characteristics of metal enrichment in Deep Bay, Hong Kong.

Sediment cores, suspended particles and overlying water were collected in Deep Bay, Hong Kong. Enrichment of Zn in surface sediments in the landward direction and the decreasing of exchangeable Cd, Ni and Zn in sediment from the inner bay to the outer bay indicated the influence of anthropogenic pollutants discharged from the riparian runoffs.