scholarly journals Phosphorus Transport in a Lowland Stream Derived from a Tracer Test with 32P

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1030
Author(s):  
Damian Zięba ◽  
Przemysław Wachniew
Keyword(s):  
Rural Areas ◽  
Transport Model ◽  
Tritiated Water ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Transient Storage ◽  
Phosphorus Transport ◽  
Lowland Stream ◽  
Beaver Dam ◽  
Small Streams

Small streams in urbanized rural areas receive loads of P from various, often episodic, sources. This paper addresses, through a tracer test with 32P, retention and transport of a pulse input of phosphorus in a 2.6 km long stretch of a channelized second-order lowland stream. Tritiated water was introduced alongside the 32P-labelled ortophosphate in order to isolate the influence of the hydrodynamic factors on P behavior. Tracer concentrations in unfiltered water samples were measured by liquid scintillation counting. Four in-stream and five hyporheic breakthrough curves were collected at four points along the stream, two of which encompass a beaver dam impoundment. The overall retention efficiency of 32P along the studied reach was 46%. The transient storage transport model OTIS-P provided reasonable fits for in-stream breakthrough curves (BTCs) but failed at reproducing the hyporheic BTCs. The overall small effect of transient storage on solute transport was higher in the stretch with a more pronounced surface storage. Transient storage and phosphorus retention were not enhanced in the beaver dam impoundment.

scholarly journals Contribution of flow conditions and sand addition on hyporheic zone exchange in gravel beds

2019 ◽  
Vol 50 (3) ◽  
pp. 878-885
Author(s):  
H. Marttila ◽  
S. Tammela ◽  
K.-R. Mustonen ◽  
P. Louhi ◽  
T. Muotka ◽  
...  
Keyword(s):  
Hyporheic Zone ◽  
Headwater Streams ◽  
Transport Model ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Flow Conditions ◽  
One Dimensional ◽  
Gravel Beds ◽  
Negative Effect ◽  
Tracer Methods

Abstract We conducted a series of tracer test experiments in 12 outdoor semi-natural flumes to assess the effects of variable flow conditions and sand addition on hyporheic zone conditions in gravel beds, mimicking conditions in headwater streams under sediment pressure. Two tracer methods were applied in each experiment: 2–5 tracer-pulse tests were conducted in all flumes and pulses were monitored at three distances downstream of the flume inlet (0 m, 5 m and 10 m, at bed surface), and in pipes installed into the gravel bed at 5 m and 10 m distances. The tracer breakthrough curves (total of 120 tracer injections) were then analysed with a one-dimensional solute transport model (OTIS) and compared with data from the gravel pipes in point-dilution pulse tests. Sand addition had a strong negative effect on horizontal fluxes (qh), whereas the fraction of the median travel time due to transient storage (F200) was determined more by flow conditions. These results suggest that even small additions of sand can modify the hyporheic zone exchange in gravel beds, thus making headwater streams with low sediment transport capacity particularly vulnerable to sediments transported into the stream from catchment land use activities.

Parameter Determination for Chloride and Tritium Transport in Undisturbed Lysimeters during Steady Flow

1992 ◽  
Vol 23 (2) ◽  
pp. 89-104 ◽  
Author(s):  
Ole H. Jacobsen ◽  
Feike J. Leij ◽  
Martinus Th. van Genuchten
Keyword(s):  
Experimental Data ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Time Moment ◽  
Breakthrough Curves ◽  
Coarse Sand ◽  
Retardation Factor ◽  
Parameter Determination ◽  
Model Parameters ◽  
Water Fraction

Breakthrough curves of Cl and 3H2O were obtained during steady unsaturated flow in five lysimeters containing an undisturbed coarse sand (Orthic Haplohumod). The experimental data were analyzed in terms of the classical two-parameter convection-dispersion equation and a four-parameter two-region type physical nonequilibrium solute transport model. Model parameters were obtained by both curve fitting and time moment analysis. The four-parameter model provided a much better fit to the data for three soil columns, but performed only slightly better for the two remaining columns. The retardation factor for Cl was about 10 % less than for 3H2O, indicating some anion exclusion. For the four-parameter model the average immobile water fraction was 0.14 and the Peclet numbers of the mobile region varied between 50 and 200. Time moments analysis proved to be a useful tool for quantifying the break through curve (BTC) although the moments were found to be sensitive to experimental scattering in the measured data at larger times. Also, fitted parameters described the experimental data better than moment generated parameter values.

Phosphorus transport in saturated slag columns: experiments and mathematical models

1996 ◽  
Vol 34 (1-2) ◽  
pp. 153-160 ◽  
Author(s):  
S. H. Lee ◽  
S. Vigneswaran ◽  
K. Bajracharya
Keyword(s):  
Mathematical Models ◽  
Sorption Capacity ◽  
Algal Blooms ◽  
Sandy Loam ◽  
Dynamic Condition ◽  
Water Environment ◽  
Breakthrough Curves ◽  
Column Experiments ◽  
Phosphorus Transport ◽  
Waste Products

Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.

scholarly journals Contaminant transfer and hydrodispersive parameters in basaltic lava flows: artificial tracer test and implications for long-term management

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
G. Bertrand ◽  
H. Celle-Jeanton ◽  
F. Huneau ◽  
A. Baillieux ◽  
G. Mauri ◽  
...  
Keyword(s):  
Point Source ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Lava Flows ◽  
Advective Transport ◽  
Mean Velocity ◽  
Volcanic System ◽  
Massif Central ◽  
Transit Times ◽  
Potential Contaminant

AbstractThe aim of this paper is to evaluate the vulnerability after point source contamination and characterize water circulations in volcanic flows located in the Argnat basin volcanic system (Chaîne des Puys, French Massif Central) using a tracer test performed by injecting a iodide solution. The analysis of breakthrough curves allowed the hydrodispersive characteristics of the massive lava flows to be determined. Large Peclet numbers indicated a dominant advective transport. The multimodal feature of breakthrough curves combined with high values of mean velocity and low longitudinal dispersion coefficients indicated thatwater flows in an environment analogous to a fissure system, and only slightly interacts with a low porosity matrix (ne < 1%). Combining this information with lava flow stratigraphy provided by several drillings allowed a conceptual scheme of potential contaminant behaviour to be designed. Although lava flows are vulnerable to point source pollution due to the rapid transfer of water within fractures, the saturated scoriaceous layers located between massive rocks should suffice to strongly buffer the transit of pollution through dilution and longer transit times. This was consistent with the low recovery rate of the presented tracer test.

scholarly journals Domestic wells have high probability of pumping septic tank leachate

2011 ◽  
Vol 8 (3) ◽  
pp. 5701-5732
Author(s):  
J. E. Horn ◽  
T. Harter
Keyword(s):  
Drinking Water ◽  
Rural Areas ◽  
High Probability ◽  
Transport Model ◽  
Regional Scale ◽  
Septic Tank ◽  
Septic Systems ◽  
Capture Zone ◽  
Septic System ◽  
Water Well

Abstract. Onsite wastewater treatment systems such as septic systems are common in rural and semi-rural areas around the world; in the US, about 25–30 % of households are served by a septic system and a private drinking water well. Site-specific conditions and local groundwater flow are often ignored when installing septic systems and wells. Particularly in areas with small lots, thus a high septic system density, these typically shallow wells are prone to contamination by septic system leachate. Typically, mass balance approaches are used to determine a maximum septic system density that would prevent contamination of the aquifer. In this study, we estimate the probability of a well pumping partially septic system leachate. A detailed groundwater and transport model is used to calculate the capture zone of a typical drinking water well. A spatial probability analysis is performed to assess the probability that a capture zone overlaps with a septic system drainfield depending on aquifer properties, lot and drainfield size. We show that a high septic system density poses a high probability of pumping septic system leachate. The hydraulic conductivity of the aquifer has a strong influence on the intersection probability. We conclude that mass balances calculations applied on a regional scale underestimate the contamination risk of individual drinking water wells by septic systems. This is particularly relevant for contaminants released at high concentrations, for substances which experience limited attenuation, and those being harmful even in low concentrations.

scholarly journals Modeling of daytime HONO vertical gradients during SHARP 2009

2012 ◽  
Vol 12 (10) ◽  
pp. 27775-27819
Author(s):  
K. W. Wong ◽  
C. Tsai ◽  
B. Lefer ◽  
N. Grossberg ◽  
J. Stutz
Keyword(s):  
Boundary Layer ◽  
Gas Phase ◽  
Rural Areas ◽  
Transport Model ◽  
Vertical Transport ◽  
Formation Mechanisms ◽  
Aerosol Model ◽  
Formation Pathway ◽  
Sensitivity Studies ◽  
Urban And Rural Areas

Abstract. Nitrous Acid (HONO) acts as a major precursor of the hydroxyl radical (OH) in the urban atmospheric boundary layer in the morning and throughout the day. Despite its importance, HONO formation mechanisms are not yet completely understood. It is generally accepted that conversion of NO2 on surfaces in the presence of water is responsible for the formation of HONO in the nocturnal boundary layer, although the type of surface on which the mechanism occurs is still under debate. Recent observations of higher than expected daytime HONO concentrations in both urban and rural areas indicate the presence of unknown daytime HONO source(s). Various formation pathways in the gas-phase and on aerosol and ground surfaces have been proposed to explain the presence of daytime HONO. However, it is unclear which mechanism dominates and, in the cases of heterogeneous mechanisms, on which surfaces they occur. Vertical concentration profiles of HONO and its precursors can help in identifying the dominant HONO formation pathways. In this study, daytime HONO and NO2 vertical profiles, measured in three different height intervals (20–70 m, 70–130 m and 130–300 m) in Houston, TX during the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) are analyzed using a one-dimensional (1-D) chemistry and transport model. Model results with various HONO formation pathways suggested in the literature are compared to the the daytime HONO and HONO/NO2 ratios observed during SHARP. The best agreement of HONO and HONO/NO2 ratios between model and observations is achieved by including both a photolytic source of HONO at the ground and on the aerosol. Model sensitivity studies show that the observed diurnal variations of HONO/NO2 ratio are not reproduced by the model if there is only a photolytic HONO source on aerosol or in the gas-phase from NO2* + H2O. Further analysis of the formation and loss pathways of HONO shows a vertical dependence of HONO chemistry during the day. Photolytic HONO formation at the ground is the major formation pathway in the lowest 20 m, while a combination of gas-phase, photolytic formation on aerosol, and vertical transport is responsible for daytime HONO between 200–300 m a.g.l. HONO removal is dominated by vertical transport below 20 m and photolysis between 200–300 m a.g.l.

scholarly journals Pollution of Nitrates - Contaminant transport in heterogeneous porous media: a case study of the coastal aquifer of Corinth, Greece

2013 ◽  
Vol 16 (1) ◽  
pp. 9-23 ◽  
Keyword(s):  
Contaminant Transport ◽  
Coastal Plain ◽  
Rural Areas ◽  
Transport Model ◽  
Heterogeneous Porous Media ◽  
Irrigated Agriculture ◽  
Plain Area ◽  
Fast Development ◽  
Alluvium Aquifer

<p>The coastal plain of Corinth, known also as Vocha plain is one of the fast-growing rural areas due to its relatively short distance from Athens. In conjunction with the fast development, water use has also increased. On a large part of the Plain area, irrigated agriculture is practiced and fertilizers are applied. The groundwater is extracted by wells (boreholes) drilled in the alluvium of Vocha Plain to meet municipal, agricultural and other water requirements. Groundwater contamination by nitrates is a problem related mainly to the spreading of organic and chemical fertilizers by farmers and, to some extent, to effluents from domestic sewage systems. Groundwater pollution in the alluvium aquifer of the Vocha Plain was investigated during a field study from July 2000 to July 2001 at eight (8) sampling periods. In this paper, the characteristics, distribution and variation of the NO3 pollution are presented using a transport model.</p>

scholarly journals Tracer Test in Fractured Chalk

1993 ◽  
Vol 24 (4) ◽  
pp. 263-274 ◽  
Author(s):  
R. Jakobsen ◽  
K. Høgh Jensen ◽  
K. L. Brettmann
Keyword(s):  
Short Duration ◽  
Transport Mechanism ◽  
Arrival Time ◽  
Porous Matrix ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Advective Transport ◽  
Long Tail ◽  
Flow Through ◽  
Chalk Aquifer

A two-well tracer test was conducted in eastern Denmark, in which a short duration pulse of lithium chloride was injected into a recharge well and made to flow through a fractured chalk aquifer to a discharge well. The wells were 25 m apart, and the concentration of lithium arriving at the discharge well was monitored at five vertical intervals in the well for a 21-day period. The observed breakthrough curves show a sharp breakthrough front, with an arrival time that is consistent with advective transport through the fractures in the chalk. The breakthrough curves also exhibit a long tail in the falling limb, suggesting the influence of a secondary transport mechanism of diffusion into the porous matrix.

scholarly journals On the ability of the Generalized Continuum Transport Model to properly capture dispersion

2018 ◽  
Vol 26 (2) ◽  
pp. 285-299
Author(s):  
Leonid Vasilyev ◽  
Florin Adrian Radu
Keyword(s):  
Velocity Distribution ◽  
Dispersion Equation ◽  
Parameter Space ◽  
Transport Model ◽  
Capillary Tube ◽  
Transition Probability ◽  
Breakthrough Curves ◽  
Advection Dispersion ◽  
Generalized Continuum ◽  
Accurate Quantification

Abstract The ability of the Generalized Continuum Transport model to describe dispersion is studied through the comparison of the breakthrough curves with an analytical solution of the linear advection-dispersion Equation. First, a velocity distribution due to Taylor dispersion in a capillary tube is related to the dispersion coeficient of the advection-dispersion equation. The same distribution is applied to the Generalized Continuum Transport model, where the dispersive flux term is not included as the term proportional to the concentration gradient. In the second stage the velocity distribution is obtained from the transition probability introduced through the Continuous Time Random Walk approach. The approaches support the idea that the Generalized Continuum Transport model captures velocity variations naturally through the parameter space. The results confirm that a proper selection of the parameter space, including its size, leads to more physical transport description as well as accurate quantification.

scholarly journals Tracer Test in Fractured Chalk

1993 ◽  
Vol 24 (4) ◽  
pp. 275-296 ◽  
Author(s):  
K.L. Brettmann ◽  
K. Høgh Jensen ◽  
R. Jakobsen
Keyword(s):  
Three Dimensional ◽  
Porous Matrix ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Dual Porosity ◽  
Local Concentration ◽  
Concentration Difference ◽  
Dual Porosity Model ◽  
Immobile Phase ◽  
Porosity Model

A two-well tracer test carried out in fractured chalk was analyzed using a three-dimensional finite-difference model for flow and transport which, was constructed on the basis of the geological and hydraulic information collected at the field site. The model was developed as a dual-porosity continuum model, in which advection was assumed to occur only in the fractures, and the water in the porous matrix was assumed to be static. The exchange of solute between the fractures (mobile phase) and the porous matrix (immobile phase) was assumed to occur as a diffusion process in response to the local concentration difference of solute between the two phases. Simulations from the dual-porosity model reproduced the shape of the observed breakthrough curves, although some portions of the tail were not accurately represented. The model was also applied as a single-porosity model for advection and dispersion in the fractures with no solute exchange with the porous matrix. The simulations from the single-porosity model greatly overestimated the observed lithium concentrations, and showed very little tailing effect in the falling limb. The study shows that, based on the given tracer test, solute transport in a fractured chalk cannot be represented by a single-porosity approach and hence when dealing with contaminant transport in such systems, both a fractured and a porous domain need to be considered.

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