Trends in nutrients in the Changjiang River

Nutrient Dynamics under the Coupling Effects of Damming and Urbanization in the Three Gorges Reservoir: Status, Sources, and Driving Factors

“…Notably, different from previous studies, the NO 3 – –N flux instead of DIN used was chosen in this study due to the limited reported DIN data for a similar season in the same region. From a long-term monitoring (1968–2020) of the Yangtze River reported by Wu et al, more than 95% of DIN consisted of NO 3 – –N during wet season. Therefore, such a substitution was assumed to be reasonable.…”

“…As mentioned in a research of Su et al, riverine N plays a pivotal role than phosphorus in triggering algal blooms. Long-term monitoring of N flux in the TGR mainstream showed a rising trend, while DSi goes to decrease slightly . Therefore, the aquatic environment of the TGR basin may pose a potential deterioration due to eutrophication.…”

“…Long-term monitoring of N flux in the TGR mainstream showed a rising trend, while DSi goes to decrease slightly. 7 Therefore, the aquatic environment of the TGR basin may pose a potential deterioration due to eutrophication. The nutrient dynamics in the TGR needs continuous attention, especially in the dissolved N flux.…”

“…River water serves as the primary conduit for the transportation of terrigenous materials and functions as a vital source of nutrients for aquatic organisms. − However, the balance of nutrients in aquatic ecosystems is facing potential threats from damming and urbanization. , Two decades ago, Humborg et al first discovered that damming leads to silicon retention, thereby sparking global attention toward the impact of dam development on nutrient dynamics. Subsequent studies have also revealed that damming leads to the retention of nutrient flux or imbalance ratios in world’s large rivers, − increasing the risk of eutrophication in the aquatic environment . Moreover, the large damming basins often coincide with rapid urbanization, resulting in alterations to land use and intensified human activities .…”

Surface-Water Nitrate Exposure to World Populations Has Expanded and Intensified during 1970–2010

“…Over the past 50 years, surface-water nitrate contamination has been rising in developed and developing regions around the world due to intensified human activities, such as intensive agriculture, nitrogen-based fertilizer use, livestock farming, land-use change, population growth and centralization, industrialization, and wastewater discharge , (Figure S1). In many surface-water systems worldwide, nitrate has been the dominant form of nitrogen and its concentrations have been observed to increase over the past decades. − The increased surface-water nitrate concentrations have become a pressing environmental concern because they cause eutrophication and associated harmful algal blooms, hypoxia, and fish deaths, posing detrimental impacts on water quality and ecosystem functioning. , Moreover, they may affect the availability and quality of drinking water and, in turn, trigger the aforementioned potential health risks to humans. However, it remains unclear how potential health risks associated with the changing surface-water nitrate exposure and their affected populations have changed worldwide over the past 50 years.…”