CARBON INPUTS AND DISTRIBUTION IN ESTUARIES OF TURBID RIVERS - THE YANGTZE AND YELLOW RIVERS (CHINA)

Particulate and dissolved organic and inorganic carbon concentrations were measured in the Yang Tze (Changjiang) and Huanghe (Yellow) river estuaries, during two different seasons. During the winter, the organi c matter in the suspended load of both estuarine systems was dominantl y of terrestrial origin, while in the summer, there were significant c ontributions from aquatic production. In these turbid rivers, there is a strong positive correlation between the concentrations of total sus pended matter and particulate organic carbon, probably because biologi cal production is inhibited when turbidity exceeds a certain limit. Di ssolved organic carbon (DOC) does not exhibit a conservative behavior in these estuarine systems. High dissolved organic carbon values in bo ttom water samples suggest remobilization of DOC from near-surface, bo ttom sediments. Dissolved inorganic carbon concentrations were very hi gh in the Huanghe River, and the trend in the calculated saturation in dices for calcite suggests precipitation of carbonate in this estuarin e system. There is no such evidence for carbonate precipitation in the Yang Tze River.