Spatial distribution of organic and pyritic sulfur in surface sediments of eutrophic Jiaozhou Bay, China: clues to anthropogenic impacts.

Anthropogenic perturbations exert important impacts on sulfur geochemistry in marine sediments. In the study, chemical extraction was used to quantify four sulfur pools, i.e., pyrite, humic-acid sulfur (HA-S), fulvic-acid sulfur (FA-S), and residual organic sulfur (ROS), in surface sediments of eutrophic Jiaozhou Bay. Results show that riverine inputs are the main control on organic matter (OM) distribution in the sediments. OM enrichment in the eastern coast is mainly due to discharges of anthropogenic wastes. Spatial coupling of pyrite and FA-S vs. TOC points to the impacts of OM enrichment on formation and preservation of pyrite and FA-S. Poor spatial coupling of HA-S vs. TOC is due to low fractions of diagenetic OS in the pool. ROS is mainly from riverine inputs and anthropogenic OS has been superimposed on this pool. Spatial coupling among TOC, pyrite-S and FA-S is a sensitive indicator of anthropogenic impacts on benthic processes of the bay.

[Distribution patterns of heavy metals in surface sediments of the Yangtze estuary and its adjacent areas and environmental quality assessment].

The concentrations of six heavy metals were determined in the fine fraction ( < 63 microm) of surface sediments in the Yangtze Estuary and its adjacent areas by an inductively coupled plasma mass spectroscopy (ICP-MS). The average contents of As, Cd, Cu, Pb, Cr and Zn are 10.47, 0.19, 37.68, 36.86, 97.80 and 98.65 mg x kg(-1), respectively. The contents of As, Cd and Cu appear gradually degressive from west to east, while the contents of Pb, Cr and Zn appear no apparent difference. In generally, the concentrations of heavy metals are higher in the south sea areas than those in the north sea areas. Environmental assessment with single factor method suggests that As, Cu, Pb, Cr and Zn are moderately contaminated, while Cd is not polluted. The values of As,Cu and Cr are between effect range-low (ERL) and effect range-median (ERM), which indicate they occasionally bring adverse biological effect at most stations, and the values of Cd,Pb and Zn are below ERL mean they rarely bring adverse biological effect by sediment quality guidelines assessment. From the results of factor analysis and cluster analysis, we conclude that the outer sea areas of the Yangtze Estuary and the Hangzhou Bay have lower sediment environmental quality, therefore much attention should be paid to these areas.

[Distribution of suspended matter concentration in the Changjiang Estuary and adjacent area after the first-stage storage of the Three Gorges Project].

The first-stage storage of the Three Gorges Project started on the 1st June, 2003 and ended on the 10th June, 2003. In order to investigate the influences of the Three Gorges Project on the Changjiang Estuary and adjacent area environment, a cruise was carried out from the 15th June, 2003 to the 25th June, 2003 to synthetically study the environment. Suspended matter concentrations (SMC) in different water layers at different sites were calculated and distributions of SMC were discussed combining with salinity and temperature of water based on recovered data. In results, SMC increase from surface to bottom in Changjiang Estuary and adjacent area. Suspended matters are enriched in the water over the river mouth bar and alongshore area which are located at the west of 123 degrees E. Compared to that before the storage, SMC are reduced obviously in the Changjiang course and south branch after the storage. For example, at the Xuliujing, SMC are reduced from 400 - 500 mg/L to 60.2 mg/L, and in the south branch, from 445 mg/L to 148 mg/L. In other areas, SMC do not show a significant change that they are both less than 10 mg/L in the surface player and 100 mg/L in bottom player. Generally, the distributed patterns of SMC in the investigation area after the storage are still similar to that before the storage.