scholarly journals Estimation of Benthic Fluxes of Dissolved Inorganic Nitrogen and Phosphorus from Sediments of the Seto Inland Sea.

1998 ◽  
Vol 7 (3) ◽  
pp. 151-158 ◽  
Author(s):  
Tamiji Yamamoto ◽  
Osamu Matsuda ◽  
Toshiya Hashimoto ◽  
Hidekazu Imose ◽  
Tomoaki Kitamura
Keyword(s):  
Inorganic Nitrogen ◽  
Seto Inland Sea ◽  
Benthic Fluxes ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen And Phosphorus ◽  
The Seto Inland Sea

scholarly journals Hydropower reservoirs on the upper Mekong River modify nutrient bioavailability downstream

2020 ◽  
Vol 7 (9) ◽  
pp. 1449-1457 ◽  
Author(s):  
Qiuwen Chen ◽  
Wenqing Shi ◽  
Jef Huisman ◽  
Stephen C Maberly ◽  
Jianyun Zhang ◽  
...  
Keyword(s):  
Climate Change Mitigation ◽  
Inorganic Nitrogen ◽  
Mekong River ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Hydraulic Residence Time ◽  
Boundary Disputes ◽  
New Perspective ◽  
Change Mitigation ◽  
Hydropower Reservoirs

Abstract Hydropower development is the key strategy in many developing countries for energy supply, climate-change mitigation and economic development. However, it is commonly assumed that river dams retain nutrients and therefore reduce downstream primary productivity and fishery catches, compromising food security and causing trans-boundary disputes. Contrary to expectation, here we found that a cascade of reservoirs along the upper Mekong River increased downstream bioavailability of nitrogen and phosphorus. The dams caused phytoplankton density to increase with hydraulic residence time and stratification of the stagnant reservoirs caused hypoxia at depth. This allowed the release of bioavailable phosphorus from the sediment and an increase in dissolved inorganic nitrogen as well as a shift in nitrogen species from nitrate to ammonium, which were transported downstream by the discharge of water from the base of the dam. Our findings provide a new perspective on the environmental impacts of river dams on nutrient cycling and ecosystem functioning, with potential implications for sustainable development of hydropower worldwide.

scholarly journals Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

2013 ◽  
Vol 10 (10) ◽  
pp. 6721-6736 ◽  
Author(s):  
C. Buzzelli ◽  
Y. Wan ◽  
P. H. Doering ◽  
J. N. Boyer
Keyword(s):  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
South Florida ◽  
External Loading ◽  
Dissolved Inorganic Nitrogen ◽  
Nutrient Inputs ◽  
Wet Season ◽  
Nitrogen And Phosphorus ◽  
Annual Variations

Abstract. Interactions among geomorphology, circulation, and biogeochemical cycling determine estuary responses to external nutrient loading. In order to better manage watershed nutrient inputs, the goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River estuary (CRE) and the St. Lucie Estuary (SLE), from 2002 to 2008. The Land–Ocean Interactions in the Coastal Zone (LOICZ) approach was used to generate water, salt, and DIN and DIP budgets. Results suggested that internal DIN production increases with increased DIN loading to the CRE in the wet season. There were hydrodynamic effects as water column concentrations and ecosystem nutrient processing stabilized in both estuaries as flushing time increased to >10 d. The CRE demonstrated heterotrophy (net ecosystem metabolism or NEM < 0.0) across all wet and dry season budgets. While the SLE was sensitive to DIN loading, system autotrophy (NEM > 0.0) increased significantly with external DIP loading. This included DIP consumption and a bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge to the SLE in 2005. Additionally, while denitrification provided a microbially-mediated N loss pathway for the CRE, this potential was not evident for the SLE where N2 fixation was favored. Disparities between total and inorganic loading ratios suggested that the role of dissolved organic nitrogen (DON) should be assessed for both estuaries. Nutrient budgets indicated that net internal production or consumption of DIN and DIP fluctuated with inter- and intra-annual variations in freshwater inflow, hydrodynamic flushing, and primary production. The results of this study should be included in watershed management plans in order to maintain favorable conditions of external loading relative to internal material cycling in both dry and wet seasons.

scholarly journals Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

2013 ◽  
Vol 10 (2) ◽  
pp. 2377-2413
Author(s):  
C. Buzzelli ◽  
Y. Wan ◽  
P. H. Doering ◽  
J. N. Boyer
Keyword(s):  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
River Estuary ◽  
South Florida ◽  
Biogeochemical Model ◽  
Dissolved Inorganic Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Tropical Estuaries ◽  
Flushing Time ◽  
Management Actions

Abstract. Interactions among watershed nutrient loading, circulation, and biogeochemical cycling determine the capacity of estuaries to accommodate introduced nutrients. Baseline quantification of loading, flushing time, export, and internal processes is essential to understand responses of sub-tropical estuaries to variable climate and nutrient loading. The goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River Estuary (CRE) and the St. Lucie Estuary (SLE), from 2002–2008 spanning various climatic conditions. The Land Ocean Interactions in the Coastal Zone (LOICZ) Biogeochemical Model was used to generate water, salt, and (DIN and DIP) budgets. The predicted increase in internal DIN production for the CRE vs. the SLE was associated with increased external DIN loading. Water column DIN concentrations decreased and stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy or balanced metabolism across all seasonal budgets. Although the SLE was also sensitive to DIN loading, system autotrophy and net ecosystem metabolism increased with DIP loading to this estuary. This included a huge DIP consumption and bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge in 2005. Additionally, while denitrification offered a loss pathway for inorganic nitrogen in the CRE, this potential was not evident for the smaller and more anthropogenically altered St. Lucie Estuary. Disparities between total and inorganic loading ratios suggested that management actions should examine the role of dissolved organic nitrogen (DON) in attempts to reduce both nitrogen and phosphorus inputs to the SLE. Establishment of quantitative loading limits for anthropogenically impacted estuaries requires an understanding of the inter-seasonal and inter-annual relationships for both N and P, circulation and flushing, variability in plankton community composition, and the dynamics of DON.

scholarly journals Analysis on the Evolution Trend of Seawater Quality and Eutrophication in Tianjin Hangu Agricultural and Fishery Area from 2010 to 2019

2021 ◽  
Vol 245 ◽  
pp. 02024
Author(s):  
Yi Chen
Keyword(s):  
Water Quality ◽  
Pollution Control ◽  
Inorganic Nitrogen ◽  
The State ◽  
Dissolved Inorganic Nitrogen ◽  
Functional Area ◽  
Nitrogen And Phosphorus ◽  
Seawater Quality ◽  
Sea Area

Through the collection and analysis of COD, dissolved inorganic nitrogen (DIN) and active phosphate monitoring data in Tianjin Hangu Agricultural and fishery area from 2010 to 2019, this paper analyzed and studied the structure of nutrients and the state of eutrophication. The results show that in recent ten years, the water quality of Tianjin Hangu Agricultural and Fishery Area has basically met the water quality requirements of functional area, the regional nitrogen pollution has been suppressed, and the eutrophication index of sea area has shown a decreasing trend year by year, but the nitrogen and phosphorus nutrient structure is still in the state of “phosphorus restriction”. Pollution control of sea areas and conservation of aquatic germplasm resources are still urgent.

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