Response of nutrient transports to water-sediment regulation events in the Huanghe basin and its impact on the biogeochemistry of the Bohai

Nutrient transport patterns in the Huanghe (Yellow River) were investigated using biogeochemical observations carried out during 2001-2011 to examine how nutrient transports were affected by water-sediment regulation events and their potential effects on the adjacent Bohai ecosystem. The concentrations and composition of nutrients in the Huanghe had an obvious change during the water-sediment regulation events, which increased dissolved nutrient transports with a similar amplitude like freshwater discharge, while amplified particulate nutrient transports. Dissolved inorganic nitrogen was the predominant species of total dissolved nitrogen. Particulate phosphorus was the major form of phosphorus affected by high content of suspended particulate matter. Phosphate represented 68% of total dissolved phosphorus. The BSi was 20% of the sum of BSi and dissolved silicate. Nutrient transport patterns highly depend on freshwater discharge. The regulation events have shifted the seasonal patterns of water and nutrient transports with high flow condition occurring at least two months prior to the normal peak flow. Abundant nutrients were transported to the coastal water and nutrient imbalance was aggravated, most likely resulting in strong impacts on the adjacent Bohai ecosystem.