Seasonal variation of nitrogen biogeochemical processes constrained by nitrate dual isotopes in cascade reservoirs, Southwestern China 

2021 ◽  
Author(s):  
Sainan Chen ◽  
Fu-Jun Yue ◽  
Xiao-Long Liu ◽  
Jun Zhong ◽  
Yuan-Bi Yi ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Fertilizer Application ◽  
Isotopic Signature ◽  
Average Concentration ◽  
Cascade Reservoirs ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
N Concentration ◽  
The Relationship

<p>The increase of affected river reaches by reservoirs has drastically disturbed the original hydrological conditions, and subsequently influenced the nutrient biogeochemistry in the aquatic system, particularly in the cascade reservoir system. To understand the seasonal variation of nitrogen (N) behaviors in cascade reservoirs, hydrochemistry and nitrate dual isotopes (δ<sup>15</sup>N-NO<sub>3</sub><sup>− </sup>and<sup></sup>δ<sup>18</sup>O-NO<sub>3</sub><sup>−</sup>) were conducted in a karst watershed (Wujiang River) in southwest China. The results showed that NO<sub>3</sub><sup>−</sup>–N accounted for almost 90% of the total dissolved nitrogen (TDN) concentration with high average concentration 3.8 ± 0.4 mg/L among four cascade reservoirs. Higher N concentration (4.0 ± 0.8 mg/L) and larger longitudinal variation were observed in summer than in other seasons. The relationship between the variation of NO<sub>3</sub><sup>−</sup>–N and dual isotopes in the profiles demonstrated that nitrification was dominated transformation, while assimilation contributed significantly in the epilimnion during spring and summer. The high dissolved oxygen concentration in the present cascade reservoirs system prevented the occurrence of N depletion processes in most of the reservoirs. Denitrification occurred in the oldest reservoir during winter with a rate ranging from 18 % to 28 %. The long-term record of surface water TDN concentration in reservoirs demonstrated an increase from 2.0 to 3.6 mg/L during the past two decades (~ 0.1 mg/L per year). The seasonal nitrate isotopic signature and continuously increased fertilizer application demonstrated that chemical fertilizer contribution significantly influenced NO<sub>3</sub><sup>−</sup>–N concentration in the karst cascade reservoirs. The research highlighted that the notable N increase in karst cascade reservoirs could influence the aquatic health in the region and further investigations were required.</p>

Long-term changes in climate, streamflow, and nutrient budgets for first-order catchments at the Experimental Lakes Area (Ontario, Canada)This paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1848-1863 ◽  
Author(s):  
Brian R. Parker ◽  
David W. Schindler ◽  
Ken G. Beaty ◽  
Michael P. Stainton ◽  
Susan E.M. Kasian
Keyword(s):  
Forest Succession ◽  
Summer Precipitation ◽  
Experimental Lakes Area ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen ◽  
Apparent Relationship ◽  
Central United States ◽  
Long Term Trends ◽  
Lake Catchment

We analyzed 36 years of records for climate, hydrology, and the chemistry of precipitation and runoff from the Lake 239 (Rawson Lake) catchment at the Experimental Lakes Area (Ontario, Canada). No evidence of significant periodicity was found for any variable in the Experimental Lakes Area records. The longer (67-year) record from nearby Kenora, Ontario, revealed a 31-year cycle in precipitation but not temperature. Significant increasing long-term trends at the Experimental Lakes Area were found for annual and winter temperature and summer precipitation and deposition of ammonium, total nitrogen (TN), and total dissolved nitrogen (TDN). Large (80%) increases in ammonium deposition appear to be related to higher emissions in the central United States. A significant negative trend for dissolved organic carbon (DOC) in precipitation cannot be explained. In runoff, significant positive trends were found for TDN and DOC in the northeast catchment and TN, TDN, ammonium, and DOC in the northwest. Significant negative trends were found for TDP and nitrate in the northeast. Significant increases were found for retention of ammonium in all catchments and DOC in the northeast and northwest. There was no apparent relationship between forest succession and retention of nutrients. Results are compared with those from three other long-term monitoring sites in eastern North America.

Corrigendum to: Long-term watershed management is an effective strategy to reduce organic matter export and disinfection by-product precursors in source water

2019 ◽  
Vol 28 (10) ◽  
pp. 822 ◽  
Author(s):  
Hamed Majidzadeh ◽  
Huan Chen ◽  
T. Adam Coates ◽  
Kuo-Pei Tsai ◽  
Christopher I. Olivares ◽  
...  
Keyword(s):  
Organic Matter ◽  
South Carolina ◽  
Watershed Management ◽  
Prescribed Fire ◽  
Management Practices ◽  
Long Term Effects ◽  
Dissolved Nitrogen ◽  
Total Dissolved Nitrogen

Watershed management practices such as prescribed fire, harvesting and understory mastication can alter the chemical composition and thickness of forest detritus, thus affecting the quantity and quality of riverine dissolved organic matter (DOM). Long-term effects of watershed management on DOM composition were examined through parallel field and extraction-based laboratory studies. The laboratory study was conducted using detritus samples collected from a pair of managed and unmanaged watersheds in South Carolina, USA. Results showed that dissolved organic carbon (DOC), total dissolved nitrogen (TDN) and ammonium (NH4+-N) concentrations were higher in water extracts from the unmanaged watershed than from the managed watershed (PPP

Grass yield in relation to potassium supply and the concentration of cations in tissue water

1993 ◽  
Vol 121 (2) ◽  
pp. 157-168 ◽  
Author(s):  
P. B. Barraclough ◽  
R. A. Leigh
Keyword(s):  
Osmotic Pressure ◽  
Water Concentration ◽  
Average Concentration ◽  
Tissue Water ◽  
Potassium Supply ◽  
K Concentration ◽  
Growing Conditions ◽  
The Relationship

SUMMARYA long-term field experiment on permanent grass at Rothamsted (UK) was studied between 1988 and 1991 to determine the relationship between soil and plant K and to identify critical soil and plant concentrations for grass yield. Maximum dry matter yield was obtained at a soil exchangeable K concentration (Kex) of 114 mg/kg dry soil (45 μм-K in the soil solution). Grass well-supplied with K maintained an average concentration ofc.200 m м-K in the tissue water of whole shoots in spring, although individual measurements varied in the range 140–320 mм, depending largely on the soil water availability. These tissue concentrations were not exceeded in soils with Kexvalues up to 800 mg/kg. Yield was reduced by 60% on plots low in K (Kexin the range 60–90 mg/kg). The yield reductions were probably due to low turgor because tissue osmotic pressures were low and potassium concentrations in tissue water (which averaged 64 mм) were probably too high to disrupt the biochemical functions of K. The results suggest that there is no universal critical tissue water concentration for K in the biophysical role of turgor maintenance, as other cations and solutes are able to substitute for it. The ultimate determinant of turgor-dependent yield loss is tissue osmotic pressure. The critical tissue osmotic pressure in grass shoots in a typical season at Rothamsted wasc.400 mosm/kg. No universal critical osmotic pressure can be expected however, as this will depend on the availability of water and therefore on growing conditions.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Risk Attitude and Corporate Investment under Output Market Uncertainty: Evidence from The Mekong River Delta, Vietnam

2016 ◽  
pp. 59-70
Author(s):  
Ninh Le Khuong ◽  
Nghiem Le Tan ◽  
Tho Huynh Huu
Keyword(s):  
Negative Relationship ◽  
Risk Attitude ◽  
Business Strategies ◽  
Risk Averse ◽  
Market Uncertainty ◽  
Firm Investment ◽  
Output Market ◽  
The Impact ◽  
The Relationship

This paper aims to detect the impact of firm managers’ risk attitude on the relationship between the degree of output market uncertainty and firm investment. The findings show that there is a negative relationship between these two aspects for risk-averse managers while there is a positive relationship for risk-loving ones, since they have different utility functions. Based on the findings, this paper proposes recommendations for firm managers to take into account when making investment decisions and long-term business strategies as well.

Financial Folly and Spain’s Black Legend

2017 ◽  
Author(s):  
Mauricio Drelichman ◽  
Hans-Joachim Voth
Keyword(s):  
Seventeenth Century ◽  
Economic History ◽  
Military Power ◽  
Great Flexibility ◽  
Loan Contracts ◽  
Historical Tradition ◽  
Black Legend ◽  
Contractual Obligations ◽  
The Relationship

This epilogue argues that Castile was solvent throughout Philip II's reign. A complex web of contractual obligations designed to ensure repayment governed the relationship between the king and his bankers. The same contracts allowed great flexibility for both the Crown and bankers when liquidity was tight. The risk of potential defaults was not a surprise; their likelihood was priced into the loan contracts. As a consequence, virtually every banking family turned a profit over the long term, while the king benefited from their services to run the largest empire that had yet existed. The epilogue then looks at the economic history version of Spain's Black Legend. The economic history version of the Black Legend emerged from a combination of two narratives: a rich historical tradition analyzing the decline of Spain as an economic and military power from the seventeenth century onward, combined with new institutional analysis highlighting the unconstrained power of the monarch.

QUALITY OF LIFE PROBLEMS OF GYNECOLOGICAL CANCER PATIENTS

2017 ◽  
Vol 63 (3) ◽  
pp. 368-374
Author(s):  
Olga Churuksaeva ◽  
Larisa Kolomiets
Keyword(s):  
Quality Of Life ◽  
Gynecological Cancer ◽  
Social Aspects ◽  
Cancer Data ◽  
Life Problems ◽  
Anticancer Treatment ◽  
Short And Long Term ◽  
The Relationship

Due to improvements in short- and long-term clinical outcomes a study of quality of life is one of the most promising trends in oncology today. This review analyzes the published literature on problems dealing with quality of life of patients with gynecological cancer. Data on quality of life with respect to the extent of anticancer treatment as well as psychological and social aspects are presented. The relationship between quality of life and survival has been estimated.

Long Term Monitoring of the Macrobenthos of the Upper Clyde Estuary

1984 ◽  
Vol 16 (5-7) ◽  
pp. 359-373 ◽  
Author(s):  
Anne R Henderson
Keyword(s):  
Water Quality ◽  
Seasonal Variation ◽  
Organic Pollution ◽  
Long Term Changes ◽  
Pollution Loading ◽  
Faunal Density ◽  
History Of ◽  
Long Term Monitoring ◽  
Term Monitoring

The sublittoral macrobenthic invertebrate populations of the Upper Clyde Estuary are described. The estuary has a long history of organic pollution. The long term changes in species composition, faunal density and dominance patterns between 1974 and 1980 are presented. The fauna is dominated by brackish, pollution tolerant oligochaetes and polychaetes. Fluctuations in populations can be related to both seasonal variation in environmental conditions and long term improvements in water quality through a reduction in pollution loading to the estuary.

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