Abstract
The Changjiang River is one of the main nutrient sources in the northwestern Pacific marginal seas. However, most of the previous studies have neglected the long-range transport (>200 km) of riverine nutrients since they are rapidly consumed. In this study, we examined the long-range transport (200-800 km) of nutrients in the surface layer during the summer of 2017. The plots of nutrients against salinity display that dissolved organic nitrogen (DON) was conservative over ~800 km, while more than 99% of the dissolved inorganic nitrogen (DIN) was removed within 200 km. As a result, in the study region, DON concentrations (avg. 7.0 ± 1.3 µM), which are minor in the river water, were much higher than DIN concentrations (avg. 0.28 ± 0.26 µM). Both nutrients, N and P, showed a similar pattern. Our results suggest that dissolved organic nutrients play a critical role on the long-range transport of riverine nutrients in surface waters and subsequent ecosystem changes.