Nitrate reduction in reactive swales at low temperatures: full-size field system vs. technical scale

2015 ◽  
Vol 15 (3) ◽  
pp. 642-648
Author(s):  
D. Wicke ◽  
P. Rouault ◽  
B. Krause Camilo ◽  
C. Pagotto ◽  
M. Dechesne ◽  
...  
Keyword(s):  
Drinking Water ◽  
Residence Time ◽  
Nitrate Reduction ◽  
Low Temperatures ◽  
Freshwater Ecosystems ◽  
Agricultural Watershed ◽  
Residence Times ◽  
Full Size ◽  
Field System ◽  
Nitrate Concentrations

Diffuse nitrate (NO3) contamination from intense agriculture adversely impacts freshwater ecosystems, and can also result in nitrate concentrations exceeding limits set in drinking water regulation, when receiving surface waters are used for drinking water production. Implementation of near-natural mitigation zones such as reactive swales or wetlands have been proven to be promising measures to reduce nitrate loads in agricultural drainage waters. However, the behavior of these systems at low temperatures and its dependence on system design has not been well known until now. In this study, the behavior of a full-scale (length: 45 m) reactive swale treating drainage water from an agricultural watershed in Brittany (France), with high nitrate concentrations in the receiving river, was monitored for one season (6 months). As flow in this full-size field system is usually restricted to winter and spring months (December–May), it usually operates at low water temperatures of 5–10 °C. Tracer tests revealed shorter than designed retention times due to high inflows and preferential flow in the swale. Results show a correlation between residence time and nitrate reduction with low removal (<10%) for short residence times (<0.1 day), increasing to >25% at residence times >10 h (0.4 day). Performance was compared to results of two technical-scale reactive swales (length: 8 m) operated for 1.5 years with two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and residence time, showing that up-scaling is a suitable approach to transferring knowledge gathered from technical-scale experiments to field conditions. For the design of new mitigation systems, one recommendation is to investigate carefully the expected inflow volumes in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.

Nitrate transfer in the Critical zone view through N & O isotopes of NO3 and CFC-SF6 groundwater residence time assessment

2020 ◽  
Author(s):  
Emmanuelle Petelet-Giraud ◽  
Nicole Baran ◽  
Virginie Vergnaud ◽  
Flora Lucassou ◽  
Jean-Michel Schroetter
Keyword(s):  
Drinking Water ◽  
Residence Time ◽  
Rural Areas ◽  
Groundwater Resources ◽  
Major Elements ◽  
Critical Zone ◽  
Basin Scale ◽  
Nitrate Concentrations ◽  
The Mean ◽  
Gas Measurements

<p>Drinking water quality in agricultural rural areas remains locally a challenge even all the effort made by local authorities to restore the groundwater resources quality, especially regarding nitrates. In Plourhan, a ~2000 inhabitants, about 10 km from the sea, NW France, the drinking water is pumped in a natural spring emerging from the Brioverian basement. The nitrate concentrations exceed the 50 mg/L standard for drinking water supply, and thus needs to be diluted to be delivered to the population. Over the last 15 years, a large programme of measures was undertaken in order to reduce the NO<sub>3</sub> concentration, including the purchase of agricultural parcels around the spring, moving progressively from mixed farming and livestock to fallows and meadows, and thus drastically change the local land use. Despite all these efforts, nitrate concentrations only decrease very slowly and remain above the 50 mg/L standard.</p><p>In this context, the objective of this study is to better understand the transfer of nitrates at the basin scale, by studying flow paths, geochemical reactions, transit times that are key parameters to estimate the vulnerability and the recovery-time of the critical zone. In that way, a geochemical and isotopic approach is applied at the basin scale. Major elements analysis of the groundwater reflect the drained contrasted lithologies as metasediments (pelites & sandstones) and amphibolite, with a large spatial heterogeneity of the NO<sub>3</sub> concentrations, ranging from a few mg/L to more than 50 mg/L. Nitrogen and oxygen isotopes of nitrates (δ<sup>15</sup>N-NO<sub>3</sub> and δ<sup>18</sup>O-NO<sub>3</sub>) suggest that denitrification can occur locally in some wells presenting low or intermediate  NO<sub>3</sub> contents, whereas other wells present high or low NO<sub>3</sub> concentrations without any evidence of denitrification processes. The mean residence time of groundwater is assessed through CFCs and SF6 dissolved gas measurements. Some wells preferentially in amphibolite, present water with low recharge temperature (around 6°C while the mean recharge temperature in Britany is 11-12°C) correlated with low CFCs/SF6 values indicating that some very old groundwater (last glaciation :  -19/17 k yrs) exists in the reservoir. Other ones in metasediments have modern water or a mixing between an old and a present day recharge. These results, together with structural and lithological detailed geological field mapping, help to draw up the conceptual model of the aquifer functioning regarding nitrates transfer in the critical zone.  </p><p>This work is part of the POLDIFF study that benefits from the funding of BRGM and the French Loire-Bretagne water Agency.</p>

scholarly journals Drinking water residence time in distribution networks and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia

2009 ◽  
Vol 7 (2) ◽  
pp. 332-343 ◽  
Author(s):  
Sarah C. Tinker ◽  
Christine L. Moe ◽  
Mitchel Klein ◽  
W. Dana Flanders ◽  
Jim Uber ◽  
...  
Keyword(s):  
Emergency Department ◽  
Drinking Water ◽  
Residence Time ◽  
Distribution Networks ◽  
Emergency Department Visits ◽  
Residence Times ◽  
Water Residence Time ◽  
Increased Risk ◽  
Ed Visits ◽  
Zip Code

We examined whether the average water residence time, the time it takes water to travel from the treatment plant to the user, for a zip code was related to the proportion of emergency department (ED) visits for gastrointestinal (GI) illness among residents of that zip code. Individual-level ED data were collected from all hospitals located in the five-county metro Atlanta area from 1993 to 2004. Two of the largest water utilities in the area, together serving 1.7 million people, were considered. People served by these utilities had almost 3 million total ED visits, 164,937 of them for GI illness. The relationship between water residence time and risk for GI illness was assessed using logistic regression, controlling for potential confounding factors, including patient age and markers of socioeconomic status (SES). We observed a modestly increased risk for GI illness for residents of zip codes with the longest water residence times compared with intermediate residence times (odds ratio (OR) for Utility 1 = 1.07, 95% confidence interval (CI)=1.03, 1.10; OR for Utility 2 = 1.05, 95% CI = 1.02, 1.08). The results suggest that drinking water contamination in the distribution system may contribute to the burden of endemic GI illness.

scholarly journals Effect of bathymetric changes on residence time in Buenaventura bay (Colombia)

DYNA ◽  
2019 ◽  
Vol 86 (211) ◽  
pp. 241-248
Author(s):  
Francisco Fernando Garcia Renteria ◽  
Mariela Patricia Gonzalez Chirino
Keyword(s):  
Finite Elements ◽  
Residence Time ◽  
Particle Tracking ◽  
Hydrodynamic Model ◽  
Residence Times ◽  
Particle Tracking Model ◽  
Tracking Model ◽  
Bathymetric Changes

In order to study the effects of dredging on the residence time of the water in Buenaventura Bay, a 2D finite elements hydrodynamic model was coupled with a particle tracking model. After calibrating and validating the hydrodynamic model, two scenarios that represented the bathymetric changes generated by the dredging process were simulated. The results of the comparison of the simulated scenarios, showed an important reduction in the velocities fields that allow an increase of the residence time up to 12 days in some areas of the bay. In the scenario without dredging, that is, with original bathymetry, residence times of up to 89 days were found.

Pyrolysis gas chromatography of some hydrocarbons

1967 ◽  
Vol 45 (23) ◽  
pp. 2913-2919 ◽  
Author(s):  
Russell Sutton ◽  
W. E. Harris
Keyword(s):  
Gas Chromatography ◽  
Stainless Steel ◽  
Residence Time ◽  
Low Temperatures ◽  
Limited Range ◽  
Chromatographic Column ◽  
Methane Formation ◽  
Pyrolysis Gas ◽  
Pyrolysis Gas Chromatography

The variables important to the development of pyrolysis gas chromatography as a means of identification of liquids and gases were studied by placing a pyrolysis tube at the inlet of a gas chromatographic column. The pyrolysis conditions can be controlled to limit the formation of methane and to yield the maximum quantities of other products for identification of the parent compounds. Conditions that reduce methane formation are the absence of air, low temperatures, a long residence time, and the use of quartz rather than stainless-steel pyrolysis tubes. There is a limited range of pyrolysis temperatures that permits the formation and observation of all products in a pyrogram.

Flow pattern and residence time of conduit flow and diffuse flow in calcareous sandstones (Bohemian Cretaceous Basin, Czech Republic)

2021 ◽  
Author(s):  
Iva Kůrková ◽  
Jiří Bruthans
Keyword(s):  
Czech Republic ◽  
Groundwater Flow ◽  
Residence Time ◽  
Dispersion Model ◽  
Tracer Tests ◽  
Water Levels ◽  
Northwestern Part ◽  
Residence Times ◽  
Karst Springs ◽  
Bohemian Cretaceous Basin

<p>Localities containing karst features were studied in the northwestern part of Bohemian Cretaceous Basin. Namely Turnov area in facies transition between coarse-delta sandstones and marlstones (Jizera Formation, Turonian) and Miskovice area in limestones and sandy limestones - sandstones (Peruc-Korycany Formation, Cenomanian). Evolution of karst conduits is discussed elsewhere (Kůrková et al. 2019).</p><p>In both localities, disappearing streams, caves and karst springs with maximum discharge up to 100 L/s were documented. Geology and hydrogeology of this area was studied from many points of view to describe formation of karst conduits and characterize groundwater flow. Tracer tests were performed using NaCl and Na-fluoresceine between sinkholes and springs under various flow rates to evaluate residence times of water in conduits and to describe geometry of conduits. Breatkthrough curves of tracer tests were evaluated by means of Qtracer2 program (Field 2002). Groundwater flow velocity in channels starts at 0.6 km/day during low water levels up to 15 km/day during maximum water levels, the velocity increases logarithmically as a function of discharge. Similar karst conduits probably occur in other parts of Bohemian Cretaceous Basin where lot of large springs can be found.</p><p>Mean residence time of difussed flow based on tritium, CFC and SF<sub>6</sub> sampled at karst springs is 20 years for 75% of water and 100 years for remaining 25%, based on binary mixing dispersion model. This shows that most of the water drained by karst conduits is infiltrated through the soil and fractured environment with relatively high residence time. Residence times in different types of wells and springs were also measured in whole north-western part of Bohemian Cretaceous Basin. Results indicate long residence times in semi-stagnant zones represented by monitoring wells and short residence times in preferential zones represented by springs and water-supply wells.</p><p> </p><p>Research was funded by the Czech Science Foundation (GA CR No. 19-14082S), Czech Geological Survey – internal project 310250</p><p> </p><p>Field M. (2002): The QTRACER2 program for Tracer Breakthrough Curve Analysis for Tracer Tests in Karstic Aquifers and Other hydrologic Systems. – U.S. Environmental protection agency hypertext multimedia publication in the Internet at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=54930.</p><p>Kůrková I., Bruthans J., Balák F., Slavík M., Schweigstillová J., Bruthansová J., Mikuš P., Grundloch J. (2019): Factors controlling evolution of karst conduits in sandy limestone and calcareous sandstone (Turnov area, Czech Republic). Journal of Hydrology: 574: 1062-1073</p>

Nitrate concentrations in drinking water and the relation to different crop types production in the province of Valencia (Spain)

1998 ◽  
Vol 55 (3) ◽  
pp. 219-231
Author(s):  
M. M. Morales Suarez‐Varela ◽  
A. Llopis Gonzalez ◽  
M. L. Tejerizo Perez ◽  
P. Marti Requena
Keyword(s):  
Drinking Water ◽  
Nitrate Concentrations ◽  
Crop Types

Using hillslope-scale groundwater model to bridge the gap between basin inputs and river concentrations. The case of nitrates in Brittany (France).

2021 ◽  
Author(s):  
Luca Guillaumot ◽  
Luc Aquilina ◽  
Jean-Raynald de Dreuzy ◽  
Jean Marçais ◽  
Patrick Durand
Keyword(s):  
Spatial Variability ◽  
Groundwater Resources ◽  
Residence Times ◽  
Groundwater Model ◽  
Nitrogen Inputs ◽  
Nitrate Concentrations ◽  
Physically Based ◽  
Nutrient Surplus ◽  
Hillslope Scale

<p>Over the past decades, intensive agriculture has altered surface water and groundwater resources quality. Nutrient surplus increased nitrate concentrations in groundwater and rivers resulting in eutrophication or drinking water risk having ecosystem, sanitary and economic repercussions. Legislations led to a reduction of agricultural inputs of nitrogen since 1990’s followed by a decrease of nitrate concentrations in rivers, but still difficult to predict and evaluate. Indeed, the incomplete knowledge of the spatial variability of climate and nitrogen inputs, cumulated to the unknown groundwater heterogeneity,  leads to hydrological and biogeochemical processes difficult to model. This study deals with the long-term variations (~decades) of nitrate concentrations in three rivers (~30 km² catchment) located in Brittany. Thus, we focus on groundwater modelling because they constitute the bigger hydrological reservoir. We developed a parsimonious equivalent hillslope-scale groundwater model. The model parameterization, which controls hydrological functioning such as mean groundwater residence times, young water contribution to the river or denitrification, relies on long-term monitored streamflow and nitrate river concentrations. In addition, dissolved CFC were sampled in the catchments. Finally, we found that uncertainty on simulated nitrate river concentrations is low. The physically-based model also brings information on temporal and spatial variability of groundwater residence times highlighting the relative importance of young (1-5 yr) and old waters (~decades) for nitrate river concentrations. Moreover, calibrated models show similar trends looking at two fictive input scenarios from 2015 to 2050.</p>

scholarly journals Drinking water quality in schools of the Santarém region, Amazon, Brazil, and health implications for school children

2018 ◽  
Vol 13 (6) ◽  
pp. 1 ◽  
Author(s):  
Marina Smidt Celere Meschede ◽  
Bernardino Ribeiro Figueiredo ◽  
Renato Igor da silva Alves ◽  
Susana Inés Segura-Muñoz
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Health Risk ◽  
School Children ◽  
Water Samples ◽  
Local Governments ◽  
Drinking Water Quality ◽  
Aluminium Content ◽  
Health Implications ◽  
Nitrate Concentrations

The quality of drinking water and its health implications for school children were examined at schools in the Santarém region, Amazon, Brazil. In this region, the population is fully supplied by groundwater from the voluminous Alter do Chão aquifer. Drinking water samples from three schools in Santarem city and from one school at the rural Mojuí dos Campos town were subjected to microbiological and physicochemical compositional analyses. The health risk of human exposure to chemical compounds through water intake was also evaluated. The results indicated that most water samples were contaminated with total coliform and with E. coli, which could cause serious intestinal disorders for school children. Drinking water was acidic and most of the chemical element concentrations were within Brazilian water potability recommended levels. One exception was the high aluminium content in schools from Santarem served by shallower wells, suggesting that further epidemiological studies are necessary and the monitoring of exposed school children should not be discarded. Elevated nitrate concentrations were also noted in schools from Santarém with shallower wells, indicating lack of sanitation and the importance of periodic monitoring of drinking water to prevent adverse health effects. Quantification of human health risk indicated a hazard in schools served by shallower wells, with aluminium as the main pollutant, followed by nitrate. The results showed that most drinking water quality parameters are in accordance with Brazilian legislation. However, microbiological contamination, water acidity, aluminium and nitrate concentrations must be taken into consideration for local governments in order to prevent related diseases among school children.

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