Anthropogenic impacts on nutrient variability in the lower Yellow River

• Published in: The Science of the total environment Vol. 755; no. Pt 1; p. 142488
• Main Authors: Wu, Nian, Liu, Su-Mei, Zhang, Gui-Ling, Zhang, Hong-Mei
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.02.2021
• Subjects: China; Compositions and fluxes; environment; Environmental and societal impacts; Environmental Monitoring; fertilizer rates; Fertilizers; global change; inorganic phosphorus; issues and policy; Nitrogen - analysis; nutrient content; Nutrients; organic phosphorus; Phosphorus - analysis; phytoplankton; Rivers; runoff; sediment contamination; sewage; sewage treatment; silicon; total dissolved phosphorus; urbanization; vegetation; Water Pollutants, Chemical - analysis; water quality; Yellow River; China; Yellow River; Nutrients; Compositions and fluxes; Environmental and societal impacts; Yellow River
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.142488

Excessive nutrient discharges and changes in nutrient ratios caused by global change and anthropogenic activities have been reported in global rivers; however, the actual alterations occurring in the Yellow River environment is too fast to catch up with. From 2001 to 2018, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) and dissolved silicon (DSi) concentrations showed decreasing trends in the lower Yellow River throughout the study period. Dissolved organic phosphorus (DOP) concentrations increased since 2009, reaching up to 95% of the total dissolved phosphorus. Annual minimum dissolved organic nitrogen concentrations increased with time. We observed extremely low nutrient concentration events since 2014 in response to the retention effect of large reservoirs; this significantly reduced the downstream water discharge and sediment load and increased phytoplankton uptake. To further analyze the variability of nutrient fluxes, we quantified the fluxes to the Yellow River from natural (runoff, precipitation deposition, and sediment load from the Loess Plateau), anthropogenic (recharged water, fertilizer application, and vegetation coverage), social and industrial (population urbanization, GDP, and sewage effluents) sources. The highest contributions of total nutrient fluxes emptied into the Yellow River was fertilizer losing (44–48%) for DIN, sewage effluents (85–88%) for DIP, and runoff (35–65%) for DSi, respectively. Strictly controlling the amount of fertilizer and improving the application methods, improving sewage treatment technology, and vigorously promoting “green travel” might reduce nutrients emptied into the Yellow River based on the main sources of nutrients. Our study may help policy makers formulate strategies and it is possible to own a better water quality in the Yellow River. [Display omitted] •Dissolved inorganic nutrients decreased during 2001-2018 in the lower Yellow River.•Dam construction and phytoplankton uptake significantly lowered nutrient concentrations.•The nutrient loading to the Yellow River derived from environmental and societal impacts were quantified.•Total nutrient influxes for DIN, DIP and DSi were mainly from fertilizer loss, sewage effluents and runoff, respectively.