Program

Coastal waters in China suffered extensive human perturbation, and consequently hypoxia and even algal blooms widely occurred.  Based on our investigation in several coastal and estuarine waters in China, we observed that riverine particles play a key role in moderating the cycling of metals, e.g., releasing Cd, Mn, Cu, and sequestering anions including molybdate. These metals-enriched/depleted particles experienced further releases/enrichment of dissolved constituents including Fe and Mn, and Mo during precipitation. These processes were highest in the low salinity anoxic estuarine waters, During Summer high river discharges, a series of dissolved constituents could be further flushed outwards including Fe, and Mn. Particularly, the high abundances of picophytoplankton (mainly as Synechococcus) and heterotrophic bacteria, commonly appeared along with these increased levels of dissolved constituents. Our observation provides clear evidence that estuarine and coastal waters serve as a critical net sink for most elements, while remobilization of these elements further play a key role in triggering the growth of specific marine phytoplankton and bacteria respectively. These processes have been intensified under the currently increased human perturbation.