Nitrogen concentrations in flow separated river water

2020 ◽  
Author(s):  
Jørgen Windolf ◽  
Hans Thodsen ◽  
Henrik Tornbjerg ◽  
Brian Kronvang ◽  
Peter B. Sørensen
Keyword(s):  
Coastal Waters ◽  
Stream Water ◽  
Base Flow ◽  
Rate Of Change ◽  
Data Set ◽  
Flow Component ◽  
The Past ◽  
N Concentration ◽  
N Removal ◽  
The Impact

<p>Nitrogen (N) loads and concentrations have been successfully reduced in most Danish streams during the last 30 years. Thereby also reducing the impact of the main driver of marine eutrophication in Danish coastal waters. However, the trend in N-loads and concentrations vary substantially among the monitored streams. The understanding of this variation are of great importance and interest for the evaluation of measures implemented to combat N eutrophication and for forecasting of effects of further measures.</p><p>River hydrographs can be split into base flow and quick flow components and the N concentrations in these two components can, thereafter, be calculated. The N concentration in the two components varies over time showing both longer term and seasonal variation. The quick flow component typically having a high variation reflecting present days leaching of N from fields and this strata has been significantly reduced during the last 3 decades due to a more sustainable farming practices.</p><p>During base flow conditions, stream water typically holds less nitrogen due to N removal in groundwater. Reductions in agricultural nitrogen leaching over the past three decades has reduced concentrations in the quick flow component and reduced the load to ground water aquifers. As groundwater aquifers are often large with a capacity of several years of recharge, the response in base flow N-concentrations is expected to be slow compared to the response in quick flow. The low response of the N-concentrations in base flow have implications on the rate of change of the river concentrations and consequently riverine N-loads to coastal waters. In some cases, the base flow N-concentration might still be influenced by the larger N-leaching of the past (1960-1990).</p><p>We have analyzed a national data set for developments in N-concentrations during base flow and quick flow. The data set covers the in country range in catchment size, land use and geology. The data set spans 29 years covering the period 1990 – 2018. In addition, measurements from a few streams monitored for a longer period have been included in the analyses</p>

scholarly journals Nitrogen concentrations in a small Mediterranean stream: 1. Nitrate 2. Ammonium

2002 ◽  
Vol 6 (3) ◽  
pp. 539-550 ◽  
Author(s):  
A. Butturini ◽  
F. Sabater
Keyword(s):  
Hyporheic Zone ◽  
Nitrate Concentration ◽  
Stream Water ◽  
Rate Of Change ◽  
Ammonium Concentration ◽  
Precipitation Regime ◽  
Concentration Variance ◽  
N Concentration ◽  
Storm Flow ◽  
Nitrogen Concentrations

Abstract. The importance of storm frequency as well as the groundwater and hyporheic inputs on nitrate (NO3-N) and ammonium (NH4-N) levels in stream water were studied in a small perennial Mediterranean catchment, Riera Major, in northeast Spain. NO3-N concentrations ranged from 0.15 to 1.9 mg l-1. Discharge explained 47% of the annual NO3-N concentration variance, but this percentage increased to 97% when single floods were analysed. The rate of change in nitrate concentration with respect to flow, ΔNO3-N/ΔQ, ranged widely from 0 to 20 μg NO3-N s l-2. The ΔNO3-N/ΔQ values fitted to a non linear model with respect to the storm flow magnitude (ΔQ) (r2=0.48, d.f.=22, P<0.01). High values of ΔNO3-N/ΔQ occurred at intermediate ΔQ values, whereas low ΔNO3-N/ΔQ values occurred during severe storms (ΔQ > 400 l s-1). N3-N concentrations exhibit anticlockwise hysteresis patterns with changing flow and the patterns observed for autumnal and winter storms indicated that groundwater was the main N3-N source for stream and hyporheic water. At baseflow, NO3-N concentration in groundwater was higher (t=4.75, d.f.=29, P>0.001) and co-varied with concentrations in the stream (r=0.91, d.f.=28, P<0.001). In contrast, NO3-N concentration in hyporheic water was identical to that in stream water. The role of the hyporheic zone as source or sink for ammonium was studied hyporheic was studied comparing its concentrations in stream and hyporheic zone before and after a major storm occurred in October 1994 that removed particulate organic matter stored in sediments. Results showed high ammonium concentrations (75±28 s.d. μg NH4-N l-1) before the storm flow in the hyporheic zone. After the storm, the ammonium concentration in the hyporheic dropped by 80% (13.6±8 μg N4-N l-1) and approached to the level found in stream water (11±8 μg NH4-N l-1) indicating that indisturbed hyporheic sediments act as a source for ammonium. After the storm, the ammonium concentrations in the stream, hyporheic and groundwater zones were very similar suggesting that stream ammonium concentrations are sustained mainly by input from groundwater. The present study provides evidence that storm flow magnitude is an important source of variability of nitrate concentration and fluxes in Mediterranean streams subjected to an irregular precipitation regime with prolonged dry periods.

scholarly journals The impact of river regulation in the Tigris and Euphrates on the Arvandroud Estuary

2020 ◽  
Vol 44 (6) ◽  
pp. 948-970 ◽  
Author(s):  
Ali Torabi Haghighi ◽  
Mojtaba Sadegh ◽  
Joy Bhattacharjee ◽  
Mehmet Emin Sönmez ◽  
Mojtaba Noury ◽  
...  
Keyword(s):  
Flow Regime ◽  
Iraq War ◽  
River Flow ◽  
Remote Sensing Data ◽  
River Regulation ◽  
Rate Of Change ◽  
The Past ◽  
New Information ◽  
Flow Changes ◽  
The Impact

The Arvandroud river (also known as Shatt-al-Arab) and its estuary have been degraded due to the changing river flow regime in the Tigris and Euphrates. This study assessed changes in flow from the major rivers and the impacts on the estuary. To assess the river flow changes, three major flow regime attributes were computed: timing (TIF), magnitude (MIF), and variability (VIF). By combining these indices, the total flow regime impact factor (IF) was scaled between 0 and 1, and classified into five groups: Low (0.80<IF<1.0), Incipient (0.60<IF<0.80), Moderate (0.40<IF<0.60), Severe (0.2<IF<0.40), and Drastic (0.0<IF<0.20). Flow regime impact maps were then created for 1941–1955, 1960–1970, 1975–1984, and 1990–2000. These revealed that, over time, the impact has extended along the basin from downstream to upstream, with a significant flow regime change from 1941–1955 to 1990–2000 in the Tigris, Euphrates, and Arvandroud. Analysis of remote sensing data revealed that the change in the flow regime has led to land degradation in the Arvandroud estuary during the past 46 years (1972–2018). In addition, the impact of the Iran–Iraq war (based on degradation of vegetation cover between 1985 and 1988) is 5.1 times of mean rate of change during 1972–2018. This study thus contributes new information on estuaries and the impact of upstream land and water use change.

scholarly journals An analysis of the long-term variation in stream water quality for three upland catchments at Loch Dee (Galloway, S.W. Scotland) under contrasting land management

2004 ◽  
Vol 8 (3) ◽  
pp. 422-435 ◽  
Author(s):  
S. J. Langan ◽  
D. Hirst
Keyword(s):  
Water Quality ◽  
Land Management ◽  
Stream Water ◽  
Base Flow ◽  
Sea Salt ◽  
Stream Water Quality ◽  
Short Term ◽  
Term Variation ◽  
The Impact

Abstract. A long term record of water chemistry, consisting of twenty years of weekly spot samples, from three sub-catchments draining into a loch and the loch outflow in Galloway, S.W. Scotland have been analysed. The analysis undertaken consisted of a three component statistical trend model. The technique allows the identification of long-term, seasonal and short-term trends, as well as differentiation between base flow and high flow responses. The land usage in the three sub-catchments is moorland, forest and forest plus lime. The results show that, since the mid-1980s, there has been a gradual decline in stream-water sulphate of the same order as reductions in the deposition of non-marine sulphate. Superimposed on this trend are somewhat random but considerable perturbations to this decline, caused by sea-salt deposition. There is no evidence of changes in surface water nitrate concentrations. The influence of different land management is evident in the sulphate, nitrate and pH data, whilst variations in calcium concentrations are also a product of differences in hydrological routing and the impact of sea-salt episodes. Keywords: trend analysis, acid deposition, land management, water quality, sea-salts, Galloway, S.W. Scotland

Economic Integration and Migrant Networks: The Case of Ukrainian Migrants in the Warsaw Agglomeration

2020 ◽  
Vol 7 (54) ◽  
pp. 258-278
Author(s):  
Wojciech Maruszewski ◽  
Paweł Kaczmarczyk
Keyword(s):  
Economic Integration ◽  
Legal Status ◽  
Data Set ◽  
Migrant Networks ◽  
The Past ◽  
Employment Sector ◽  
Integration Of Immigrants ◽  
Domestic Labour ◽  
Key Dimensions ◽  
The Impact

AbstractIn the past years, Poland has been not only a country of (mass) immigration but also a country where foreigners have begun to play a much larger role in the domestic labour market than ever before. This makes the analyses of foreigners’ integration increasingly important both to understand the situation of immigrants in Poland and their impact on the national economy and social processes. In this context, this article aims to quantify one of the dimensions of the economic integration of immigrants. We look at the level of earnings as one of the indicators of their integration process. Additionally, we refer to the impact of social capital (in the form of migrant networks) on the economic situation of immigrants. We focus on immigrants from Ukraine—the most numerous group of foreigners in Poland. Based on a unique data set, we empirically identify the key dimensions that have an impact on their incomes, including gender, employment sector and legal status. We also point to the statistically significant effects of migrant networks on migrants’ earnings.

GST Pass-through Across Indian Sates: Evidence from Difference-in-Differences

2018 ◽  
Vol 66 (1-2) ◽  
pp. 42-49
Author(s):  
Debashree Das
Keyword(s):  
Ordinary Least Squares ◽  
Rate Of Change ◽  
Control Group ◽  
Short Term ◽  
Difference In Differences ◽  
Data Set ◽  
Consumer Prices ◽  
Pass Through ◽  
The Impact ◽  
Special Category

This article analyses whether there exists any short-term inflationary pressure on Indian economy post Goods and Services Tax (GST) implementation. It was found that the introduction of GST showed no significant effect on the rate of change of consumer price index (CPI). Though, the effect of the GST implementation on consumer prices in India showed no significant change in the short term, the impact needs to monitored and observed for the long term, because the current state of economic conditions may have led to a delayed pass-through of the GST increase into consumer prices. To estimate the pass-through effect on prices due to GST implementation from 1 July 2017, various graphical and statistical methods are used to ascertain whether there has been any significant pass-through of GST on CPI– ordinary least squares (OLS) regression, and difference-in differences (DID) estimation technique has been used. The impact of post- and pre-implementation of GST has been analysed through DID by segregating the data set on the basis of treatment and control groups. The non-special category states have been taken as the treatment group and remaining special category states as control group. The results indicate that there is no significant evidence of upward bias in the CPI post GST implementation; these conventional estimates hold true for all states that were segmented based on revenue distribution and contribution to gross domestic product (GDP). JEL: D78, H20, H22

scholarly journals How COVID-19 Have Changed Crowdfunding: Evidence From GoFundMe

2021 ◽  
Author(s):  
Junda Wang ◽  
Xupin Zhang ◽  
Jiebo Luo
Keyword(s):  
Racial Disparity ◽  
Computational Approach ◽  
Long Term Effects ◽  
Data Set ◽  
Unique Data ◽  
The Past ◽  
Before And After ◽  
The Impact ◽  
Shed Light

While the long-term effects of COVID-19 are yet to be determined, its immediate impact on crowdfunding is nonetheless significant. This study takes a computational approach to more deeply comprehend this change. Using a unique data set of all the campaigns published over the past two years on GoFundMe, we explore the factors that have led to the successful funding of a crowdfunding project. In particular, we study a corpus of crowdfunded projects, analyzing cover images and other variables commonly present on crowdfunding sites. Furthermore, we construct a classifier and a regression model to assess the significance of features based on XGBoost. In addition, we employ counterfactual analysis to investigate the causality between features and the success of crowdfunding. More importantly, sentiment analysis and the paired sample t-test are performed to examine the differences in crowdfunding campaigns before and after the COVID-19 outbreak that started in March 2020. First, we note that there is significant racial disparity in crowdfunding success. Second, we find that sad emotion expressed through the campaign's description became significant after the COVID-19 outbreak. Considering all these factors, our findings shed light on the impact of COVID-19 on crowdfunding campaigns.

scholarly journals Borders within Borders: The Impact of Occupational Licensing on Immigrant Incorporation

2019 ◽  
Vol 6 (1) ◽  
pp. 22-45
Author(s):  
Beth Redbird ◽  
Angel Alfonso Escamilla-García
Keyword(s):  
Financial Capital ◽  
Immigrant Incorporation ◽  
Immigrant Labor ◽  
Occupational Licensing ◽  
Data Set ◽  
The Past ◽  
Occupational Regulation ◽  
Nationally Representative ◽  
The Impact ◽  
Institutional Mechanism

Over the past four decades, occupational regulation, particularly licensing, which creates a legal right to practice, has engulfed the American occupational structure. Occupational licensure research typically offers theoretical arguments suggesting that licensing limits individuals’ entry into an occupation. For migrants arriving with little financial capital, licensing requirements can act as substantial barriers to occupational entry. On the other hand, licensing delineates, codifies, and publicizes uniform standards for occupational entry, which may have the effect of enhancing accessibility for immigrants. Using a unique longitudinal data set of occupational licensing enactments between 1994 and 2012, combined with nationally representative data from the Current Population Survey, the authors show that licensing creates institutional mechanism that can ease access into occupations for immigrants, particularly for vulnerable immigrant labor groups, particularly for (1) those arriving as adults after the acquisition of education credentials in their countries of origin and (2) those who recently entered the country and may lack the occupational social networks necessary to find and obtain jobs and the cultural capital to follow typical informal paths to entry.

Understanding the Role of Vaping in Criminal Behavior Among Adolescents

2021 ◽  
pp. 073401682110019
Author(s):  
Anthony G. Vito ◽  
Gregory C. Rocheleau ◽  
Jonathan Intravia
Keyword(s):  
Violent Crime ◽  
Criminal Behavior ◽  
Property Crime ◽  
Marijuana Use ◽  
Future Research ◽  
Data Set ◽  
The Past ◽  
12Th Grade ◽  
Monitoring The Future ◽  
The Impact

This study examines the link between ever vaped, vaped just flavoring in the past 30 days, and vaped just flavoring frequently in the past 30 days and violent crime, property crime, marijuana use, and smoking. Using the 2017 Monitoring the Future form two data set and propensity score matching, the researchers are better able to consider the impact of the vaping behavior among similarly situated 12th-grade adolescents. Results illustrate that there are no vaping behaviors linked with violent crime or property crime among similarly situated adolescents. In contrast, results show that adolescents who have ever vaped, vaped just flavoring, or vaped just flavoring frequently are linked with marijuana use and smoking. Limitations and future research implications are discussed.

scholarly journals A 2-decade (1988–2009) record of diatom fluxes in the Mauritanian coastal upwelling: impact of low-frequency forcing and a two-step shift in the species composition

2021 ◽  
Vol 18 (5) ◽  
pp. 1873-1891
Author(s):  
Oscar E. Romero ◽  
Simon Ramondenc ◽  
Gerhard Fischer
Keyword(s):  
Coastal Waters ◽  
Temporal Dynamics ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Benthic Diatoms ◽  
Time Interval ◽  
Data Set ◽  
The Impact

Abstract. Eastern boundary upwelling ecosystems (EBUEs) are among the most productive marine regions in the world's oceans. Understanding the degree of interannual to decadal variability in the Mauritania upwelling system is crucial for the prediction of future changes of primary productivity and carbon sequestration in the Canary Current EBUE as well as in similar environments. A multiyear sediment trap experiment was conducted at the mooring site CBmeso (“Cape Blanc mesotrophic”, ca. 20∘ N, ca. 20∘40′ W) in the highly productive coastal waters off Mauritania. Here, we present results on fluxes of diatoms and the species-specific composition of the assemblage for the time interval between March 1988 and June 2009. The temporal dynamics of diatom populations allows the proposal of three main intervals: (i) early 1988–late 1996, (ii) 1997–1999, and (iii) early 2002–mid 2009. The Atlantic Multidecadal Oscillation (AMO) appears to be an important driver of the long-term dynamics of diatom population. The long-term AMO-driven trend is interrupted by the occurrence of the strong 1997 El Niño–Southern Oscillation (ENSO). The extraordinary shift in the relative abundance of benthic diatoms in May 2002 suggests the strengthening of offshore advective transport within the uppermost layer of filament waters and in the subsurface and in deeper and bottom-near layers. It is hypothesized that the dominance of benthic diatoms was the response of the diatom community to the intensification of the slope and shelf poleward undercurrents. This dominance followed the intensification of the warm phase of AMO and the associated changes of the Atlantic Meridional Overturning Circulation. Transported valves (siliceous remains) from shallow Mauritanian coastal waters into the bathypelagic should be considered for the calculation and model experiments of bathy- and pelagic nutrients budgets (especially Si), the burial of diatoms, and the paleoenvironmental signal preserved in downcore sediments. Additionally, our 1988–2009 data set contributes to the characterization of the impact of low-frequency climate forcings in the northeastern Atlantic and will be especially helpful for establishing the scientific basis for forecasting and modeling future states of the Canary Current EBUE and its decadal changes.

scholarly journals Nitrogen circulation in a Mediterranean holm oak forest, La Castanya, Montseny, northeastern Spain

2002 ◽  
Vol 6 (3) ◽  
pp. 551-558 ◽  
Author(s):  
A. Avila ◽  
A. Rodrigo ◽  
F. Rodà
Keyword(s):  
Hyporheic Zone ◽  
Nitrate Concentration ◽  
Stream Water ◽  
Rate Of Change ◽  
Ammonium Concentration ◽  
Precipitation Regime ◽  
Concentration Variance ◽  
N Concentration ◽  
Storm Flow ◽  
Discharge Regime

Abstract. The importance of storm frequency as well as the groundwater and hyporheic inputs on nitrate (NO3-N) and ammonium (NH4-N) levels in stream water were studied in a small perennial Mediterranean catchment, Riera Major, in northeast Spain. NO3-N concentrations ranged from 0.15 to 1.9 mg l-1. Discharge explained 47% of the annual NO3-N concentration variance, but this percentage increased to 97% when single floods were analysed. The rate of change in nitrate concentration with respect to flow, ΔNO3-N/ΔQ, ranged widely from 0 to 20 μg NO3-N s l-2. The ΔNO3-N/ΔQ values fitted to a non linear model with respect to the storm flow magnitude (ΔQ) (r2=0.48, d.f.=22, P<0.01). High values of ΔNO3-N/ΔQ occurred at intermediate ΔQ values, whereas low ΔNO3-N/ΔQ values occurred during severe storms (ΔQ > 400 l s-1). N3-N concentrations exhibit anticlockwise hysteresis patterns with changing flow and the patterns observed for autumnal and winter storms indicated that groundwater was the main N3-N source for stream and hyporheic water. At baseflow, NO3-N concentration in groundwater was higher (t=4.75, d.f.=29, P>0.001) and co-varied with concentrations in the stream (r=0.91, d.f.=28, P<0.001). In contrast, NO3-N concentration in hyporheic water was identical to that in stream water. The role of the hyporheic zone as source or sink for ammonium was studied hyporheic was studied comparing its concentrations in stream and hyporheic zone before and after a major storm occurred in October 1994 that removed particulate organic matter stored in sediments. Results showed high ammonium concentrations (75±28 s.d. μg NH4-N l-1) before the storm flow in the hyporheic zone. After the storm, the ammonium concentration in the hyporheic dropped by 80% (13.6±8 μg N4-N l-1) and approached to the level found in stream water (11±8 μg NH4-N l-1) indicating that indisturbed hyporheic sediments act as a source for ammonium. After the storm, the ammonium concentrations in the stream, hyporheic and groundwater zones were very similar suggesting that stream ammonium concentrations are sustained mainly by input from groundwater. The present study provides evidence that storm flow magnitude is an important source of variability of nitrate concentration and fluxes in Mediterranean streams subjected to an irregular precipitation regime with prolonged dry periods. Keywords: nitrate, discharge regime, hyporheic zone, groundwater, Mediterranean, stream, Riera Major

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