scholarly journals Seasonal Variation in Nitrogen and Phosphorus Concentrations in the Mekong River at Vientiane

2007 ◽  
Vol 20 (3) ◽  
pp. 226-234 ◽  
Author(s):  
Toshiaki IIDA ◽  
Somphone INKHAMSENG ◽  
Koshi YOSHIDA ◽  
Shinnosuke ITO
Keyword(s):  
Seasonal Variation ◽  
Mekong River ◽  
Nitrogen And Phosphorus

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.

The ecological complexity of the Thai-Laos Mekong River: I. Geology, seasonal variation and human impact assessment on river quality

2010 ◽  
Vol 45 (13) ◽  
pp. 1661-1673 ◽  
Author(s):  
Veerasak Udomchoke ◽  
Patcharee Sunthornranun ◽  
Apisit Songsasen ◽  
Kantimanee Phanwichien ◽  
Pongsakorn Jiwapornkupt ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Impact Assessment ◽  
Human Impact ◽  
Mekong River ◽  
River Quality ◽  
Ecological Complexity

Investigations into the Intensive System of Grassland Management. By the Agricultural Research Staff of Imperial Chemical Industries, Limited. II. The Mineral Content of Intensively Treated Pasture and a Relationship Between the Nitrogen and Phosphorus Contents.

1931 ◽  
Vol 21 (2) ◽  
pp. 220-232 ◽  
Author(s):  
A. W. Greenhill ◽  
H. J. Page
Keyword(s):  
Seasonal Variation ◽  
Phosphoric Acid ◽  
Mineral Content ◽  
Significant Positive Correlation ◽  
Agricultural Research ◽  
Grassland Management ◽  
Early Summer ◽  
Nitrogen And Phosphorus ◽  
Research Staff ◽  
Intensive System

1. The mineral content of pastures farmed under the Intensive System of Grassland Management, and representing three to five weeks'growth, from three centres in two seasons, is reported.2. The lime content fluctuated considerably during the season, but the fluctuations showed no definite seasonal trend. The average seasonal content was practically identical in all cases.3. The phosphoric acid content showed a definite seasonal variation, falling during drought or the early summer flush period and recovering again after the drought or flush period respectively. The phosphoric acid showed consistently a very highly significant positive correlation with the nitrogen content of the herbage. The bearing of this correlation on the metabolism of the plant and on the phosphatic and nitrogenous manuring of pastures is discussed.

Seasonal variation in water chemistry over a bog-rich fen gradient in Continental Western Canada

1995 ◽  
Vol 52 (3) ◽  
pp. 587-606 ◽  
Author(s):  
Dale H. Vitt ◽  
Suzanne E. Bayley ◽  
Tai-Long Jin
Keyword(s):  
Seasonal Variation ◽  
Surface Water ◽  
Metal Ions ◽  
Water Chemistry ◽  
Base Cations ◽  
Hydrogen Ion ◽  
Western Canada ◽  
Nitrogen And Phosphorus ◽  
Surface Water Chemistry ◽  
Rich Fen

Surface and subsurface (0.5, 1.0, and 1.5 m depths) water was sampled weekly in 1989 and biweekly in 1990 during the ice-free season along a bog-rich fen gradient in central Alberta. Acidity–alkalinity were most closely related to peatland type and were the most useful parameters for characterizing peatlands. Potassium, nitrogen, and phosphorus concentrations were more related to season, year, or peatland–year interactions and cannot be used to categorize the bog–fen gradient. Hydrogen ion, ammonium, alkalinity, and corrected conductivity were relatively constant throughout the ice-free season, while total metal ions (Al, Fe, Mn, and Zn), base cations (Ca2+, Mg2+, Na+, K+), nitrate, and components of phosphorus fluctuated seasonally. Nitrate remained constant with depth in all peatland types, whereas ammonium increased with depth. Relationships of surface water chemistry to pH for all sites showed three patterns: a positive and highly significant correlation with little seasonal variation within peatland types (base cations, alkalinity, and corrected conductivity); less significant correlation with strong seasonal variation within peatland types (N and P); and a general negative and highly significant correlation with some seasonal variation in peatland types (metals and S). Water temperatures increased along the bog-rich fen gradient.

scholarly journals Estimating water availability across the Upper Salween and Mekong river basins

2015 ◽  
Vol 368 ◽  
pp. 343-349
Author(s):  
S. Liu ◽  
W. Ding ◽  
C. Liu ◽  
L. Liu ◽  
S. Bajracharya ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
River Basin ◽  
Water Availability ◽  
River Basins ◽  
Mekong River ◽  
Geographical Distance ◽  
Variation Pattern ◽  
Mekong River Basin ◽  
Upstream Station ◽  
Low Altitude

Abstract. According to Liu et al. (2014), borrowing, substituting and generating (BSG) are the main methods people used to acquire the discharge at ungauged stations. Two of the substitution (modelling and disaggregation) methods in combination with the borrowing idea are compared for simulating discharge for the Upper Salween and Mekong River Basin (USMRB). It is seen that with a simple borrowing/ disaggregating method, the Nash-Sutcliffe Efficiency (NSE) can reach 0.82. The similarity in the seasonal variation pattern is a more important requirement to identify if the two stations are to be considered as having hydrological similarity. From the experience obtained for the USMRB, an upstream station with shorter geographical distance may be more in hydrological similarity than a station in the far downstream. The NSE is quite low when borrowing occurs within the low altitude downstream region. The efficiency will be decreased when we borrow information from several stations which may be not in hydrological similarity.

Sign in / Sign up

Export Citation Format

Share Document