NITROGEN MOVEMENT NEAR SURFACE MANURE STORAGES

1976 ◽  
Vol 56 (3) ◽  
pp. 223-231 ◽  
Author(s):  
F. J. SOWDEN ◽  
F. R. HORE
Keyword(s):  
Groundwater Flow ◽  
Groundwater Contamination ◽  
Water Table ◽  
The Other ◽  
Nitrate Content ◽  
Near Surface ◽  
Concrete Base ◽  
Dug Wells ◽  
Storage Area ◽  
Manure Storage

No evidence of serious groundwater contamination by excess nutrients from solid manure storage areas that had been used for over 30 yr at the Experimental Farm, Ottawa was found in an investigation that was carried out over a period of 4 yr. One storage area was on a concrete base and the other was located on a gravel base. The water table was usually above the 275-cm depth at both sites. Two unused shallow dug wells less than 250 m from the storage areas were not contaminated by nitrate, ammonium or phosphate. Water from piezometers installed at 275- and 425-cm depths near the gravel base storage area was always low in nitrate and ammonium, but sometimes appreciable levels of nitrate were found in water from a 122-cm deep piezometer. Water from piezometers installed at 122- and 275-cm depths near the concrete base storage area usually contained nitrate and ammonium. Water from piezometers installed 213 and 241 m from the storage areas in the direction of groundwater flow contained little nitrate or ammonium. The conditions prevailing in the area and the variation in the nitrate content of the groundwater during the seasons suggested that much of the nitrate originating from the storage areas was denitrified at or near the water table.

Soil characteristics in relation to groundwater for selected Dark Brown Chernozems in southern Alberta

2010 ◽  
Vol 90 (4) ◽  
pp. 597-610 ◽  
Author(s):  
J.J. Miller ◽  
D.S. Chanasyk
Keyword(s):  
Groundwater Flow ◽  
Groundwater Recharge ◽  
Water Table ◽  
Calcareous Soil ◽  
Soil Characteristics ◽  
Water Soluble ◽  
The Other ◽  
Slope Position ◽  
Southern Alberta ◽  
Water Tables

Limited information exists on soil characteristics in relation to groundwater for undulating morainal landscapes of the Dark Brown soil zone in western Canada. A 4-yr (1985-1988) field study was conducted in southern Alberta to investigate these relationships for selected Dark Brown Chernozems. Soil morphology, physical and chemical properties of the soil horizons, water fluxes in the saturated zone, and tritium content of shallow groundwater were determined at nine sites. Three Orthic Dark Brown Chernozemic soils occurred in groundwater recharge areas with water tables ≥1.81 m, indicating that leaching of carbonates from the B horizons was consistent with downward groundwater flow. The other three Orthic soils occurred in groundwater discharge areas, and they may have developed because of deeper (≥2.60 m) water tables. High water-soluble Na in these latter three Orthic soils suggested a sodic influence from a shallower water table sometime in the recent past. The two Calcareous Dark Brown Chernozems, and saline Calcareous Dark Brown Chernozem occurred in groundwater recharge areas. One calcareous soil at a lower slope position had a shallow (0.84-2.02 m) water table, suggesting carbonates were brought upward into the Cca horizon from the groundwater. The other calcareous soil at the upper slope position had a deeper (>6.62 m) water table, suggesting carbonates were leached downward and precipitated in the Cca horizon. The saline Calcareous Dark Brown Chernozem was located in an area of groundwater recharge with a deeper (4-9 m) water table, suggesting that salinization likely occurred sometime in the past. Groundwater flow conditions during this study could not explain the genesis of some soils in this study area, suggesting that past groundwater, climatic, and environmental conditions need to be considered to explain the genesis of some relict soils.

Breaks in lithology: Interpretation problems when handling 2D structures with a 1D approximation

Geophysics ◽  
2010 ◽  
Vol 75 (4) ◽  
pp. WA179-WA188 ◽  
Author(s):  
Alan Yusen Ley-Cooper ◽  
James Macnae ◽  
Andrea Viezzoli
Keyword(s):  
Radial Distance ◽  
The Other ◽  
Conductive Layer ◽  
Near Surface ◽  
Depth Images ◽  
Modeling Methodology ◽  
Wide System ◽  
Receiver System ◽  
Airborne Electromagnetic ◽  
Detection Capabilities

Most airborne electromagnetic (AEM) data are processed using successive 1D approximations to produce stitched conductivity-depth sections. Because the current induced in the near surface by an AEM system preferentially circulates at some radial distance from a horizontal loop transmitter (sometimes called the footprint), the section plotted directly below a concentric transmitter-receiver system actually arises from currents induced in the vicinity rather than directly underneath. Detection of paleochannels as conduits for groundwater flow is a common geophysical exploration goal, where locally 2D approximations may be valid for an extinct riverbed or filled valley. Separate from effects of salinity, these paleochannels may be conductive if clay filled or resistive if sand filled and incised into a clay host. Because of the wide system footprint, using stitched 1D approximations or inversions may lead to misleading conductivity-depth images or sections. Near abrupt edges of an extensive conductive layer, the lateral falloff in AEM amplitudes tends to produce a drooping tail in a conductivity section, sometimes coupled with alocal peak where the AEM system is maximally coupled to currents constrained to flow near the conductor edge. Once the width of a conductive ribbon model is less than the system footprint, small amplitudes result, and the source is imaged too deeply in the stitched 1D section. On the other hand, a narrow resistive gap in a conductive layer is incorrectly imaged as a drooping region within the layered conductor; below, the image falsely contains a blocklike poor conductor extending to depth. Additionally, edge-effect responses often are imaged as deep conductors with an inverted horseshoe shape. Incorporating lateral constraints in 1D AEM inversion (LCI) software, designed to improve resolution of continuous layers, more accurately recovers the depth to extensive conductors. The LCI, however, as with any AEM modeling methodology based on 1D forward responses, has limitations in detecting and imaging in the presence of strong 3D lateral discontinuities of dimensions smaller than the annulus of resolution. The isotropic, horizontally slowly varying layered-earth assumption devalues and limits AEM’s 3D detection capabilities. The need for smart, fast algorithms that account for 3D varying electrical properties remains.

THE EFFECT OF GROUNDWATER ON SOIL FORMATION IN A MORAINAL LANDSCAPE IN SASKATCHEWAN

1985 ◽  
Vol 65 (2) ◽  
pp. 293-307 ◽  
Author(s):  
J. J. MILLER ◽  
D. F. ACTON ◽  
R. J. ST. ARNAUD
Keyword(s):  
Groundwater Flow ◽  
Water Table ◽  
Soil Formation ◽  
Lateral Flow ◽  
Dominant Factor ◽  
Slope Position ◽  
Soluble Salts ◽  
Runoff Water ◽  
Depth To Water Table ◽  
Water Tables

The results of this study indicate the importance of groundwater flow and water table depth on the genesis, characteristics and distribution of soils within a hummocky morainal landscape. Non-saline and non-carbonated soils in upland depressions can be attributed to "depression-focused" recharge by snowmelt and snowmelt runoff in the spring, as evidenced by deep sola and/or eluvial horizons. Non-saline and carbonated soils on lower slopes adjacent to depressions are associated with local discharge and/or lateral flow from the adjacent groundwater mounds under the depressions in spring, as well as upward flow in the summer resulting from water use by phreatophytes such as willows, creating a water table depression around the slough fringes. Saline and carbonated soils at low elevations are associated with shallow and rather stable water tables, and local discharge from surrounding uplands. Soil types on uplands are more dependent on slope position and infiltration than on depth to water table or groundwater flow. Non-saline soils of different profile types occur on mid- and upper slope positions. These areas have a deep water table with mainly recharge or lateral flow occurring in the saturated zone. The infiltration of surface runoff water in upland depressions is the dominant factor influencing the distribution of soluble salts in this hummocky landscape. Key words: Water table, landscape position, recharge, discharge, soluble salts, soil genesis, morphology, carbonate soil

Study on Load Stress of Lean Concrete Base in Asphalt Pavement

2012 ◽  
Vol 178-181 ◽  
pp. 1495-1498
Author(s):  
Li Jun Suo
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Asphalt Pavement ◽  
Element Model ◽  
Pavement Design ◽  
The Other ◽  
Three Dimension ◽  
Traffic Loading ◽  
Concrete Base

Load stress, which is caused by traffic loading, is important parameter used in the analysis of the new pavement design. In order to study the load stress of lean concrete base in the asphalt pavement, first of all, three–dimension finite element model of the asphalt pavement is established. The main objectives of the paper are investigated. One is calculation for load stress of lean concrete base, and the other is analysis for relationship between load stress of lean concrete base and parameters, such as thickness, modulus. The results show that load stress of lean concrete base decreases, decreases and increases with increase of base’s thickness, surface’s thickness and ratio of base’s modulus to foundation’s modulus respectively. So far as the traffic axle loading is concerned, it has a significant impact on load stress of lean concrete base, and it can be seen from results that when load is taken from 100kN to 220kN, load stress increases quickly with the increase of the traffic axle loading.

scholarly journals Biogeochemical Regimes in Shallow Aquifers Reflect the Metabolic Coupling of the Elements Nitrogen, Sulfur, and Carbon

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Carl-Eric Wegner ◽  
Michael Gaspar ◽  
Patricia Geesink ◽  
Martina Herrmann ◽  
Manja Marz ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Groundwater Flow ◽  
Inorganic Nitrogen ◽  
Sulfur Metabolism ◽  
Ammonium Oxidation ◽  
Metabolic Potential ◽  
Differentiation Potential ◽  
Near Surface ◽  
Monitoring Wells

ABSTRACTNear-surface groundwaters are prone to receive (in)organic matter input from their recharge areas and are known to harbor autotrophic microbial communities linked to nitrogen and sulfur metabolism. Here, we use multi-omic profiling to gain holistic insights into the turnover of inorganic nitrogen compounds, carbon fixation processes, and organic matter processing in groundwater. We sampled microbial biomass from two superimposed aquifers via monitoring wells that follow groundwater flow from its recharge area through differences in hydrogeochemical settings and land use. Functional profiling revealed that groundwater microbiomes are mainly driven by nitrogen (nitrification, denitrification, and ammonium oxidation [anammox]) and to a lesser extent sulfur cycling (sulfur oxidation and sulfate reduction), depending on local hydrochemical differences. Surprisingly, the differentiation potential of the groundwater microbiome surpasses that of hydrochemistry for individual monitoring wells. Being dominated by a few phyla (Bacteroidetes,Proteobacteria,Planctomycetes, andThaumarchaeota), the taxonomic profiling of groundwater metagenomes and metatranscriptomes revealed pronounced differences between merely present microbiome members and those actively participating in community gene expression and biogeochemical cycling. Unexpectedly, we observed a constitutive expression of carbohydrate-active enzymes encoded by different microbiome members, along with the groundwater flow path. The turnover of organic carbon apparently complements for lithoautotrophic carbon assimilation pathways mainly used by the groundwater microbiome depending on the availability of oxygen and inorganic electron donors, like ammonium.IMPORTANCEGroundwater is a key resource for drinking water production and irrigation. The interplay between geological setting, hydrochemistry, carbon storage, and groundwater microbiome ecosystem functioning is crucial for our understanding of these important ecosystem services. We targeted the encoded and expressed metabolic potential of groundwater microbiomes along an aquifer transect that diversifies in terms of hydrochemistry and land use. Our results showed that the groundwater microbiome has a higher spatial differentiation potential than does hydrochemistry.

scholarly journals Atmospheric electric field in the Atlantic marine boundary layer: first results from the SAIL project

2020 ◽  
Author(s):  
Susana Barbosa ◽  
Mauricio Camilo ◽  
Carlos Almeida ◽  
José Almeida ◽  
Guilherme Amaral ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Electric Field ◽  
Marine Boundary Layer ◽  
Weather Conditions ◽  
Cape Verde ◽  
The Other ◽  
Atmospheric Electric Field ◽  
Fair Weather ◽  
Near Surface ◽  
First Results

<p><span>The study of the electrical properties of the atmospheric marine boundary layer is important as the effect of natural radioactivity in driving near surface ionisation is significantly reduced over the ocean, and the concentration of aerosols is also typically lower than over continental areas, allowing a clearer examination of space-atmosphere interactions. Furthermore, cloud cover over the ocean is dominated by low-level clouds and most of the atmospheric charge lies near the earth surface, at low altitude cloud tops. </span></p><p><span>The relevance of electric field observations in the marine boundary layer is enhanced by the the fact that the electrical conductivity of the ocean air is clearly linked to global atmospheric pollution and aerosol content. The increase in aerosol pollution since the original observations made in the early 20th century by the survey ship Carnegie is a pressing and timely motivation for modern measurements of the atmospheric electric field in the marine boundary layer. Project SAIL (Space-Atmosphere-Ocean Interactions in the marine boundary Layer) addresses this challenge by means of an unique monitoring campaign on board the ship-rigged sailing ship NRP Sagres during its 2020 circumnavigation expedition. </span></p><p><span>The Portuguese Navy ship NRP Sagres departed from Lisbon on January 5th in a journey around the globe that will take 371 days. Two identical field mill sensors (CS110, Campbell Scientific) are installed </span><span>o</span><span>n the mizzen mast, one at a height of 22 m, and the other at a height of 5 meters. </span><span>A visibility sensor (SWS050, Biral) was also set-up on the same mast in order to have measurements of the extinction coefficient of the atmosphere and assess fair-weather conditions.</span><span> Further observations include gamma radiation measured with a NaI(Tl) scintillator from 475 keV to 3 MeV, cosmic radiation up to 17 MeV, and atmospheric ionisation from a cluster ion counter (Airel). The</span><span> 1 Hz measurements of the atmospheric electric field</span><span> and from all the other sensors</span><span> are </span><span>linked to the same rigorous temporal reference frame and precise positioning through kinematic GNSS observations. </span></p><p><span>Here the first results of the SAIL project will be presented, focusing on fair-weather electric field over the Atlantic. The observations obtained in the first three sections of the circumnavigation journey, including Lisbon (Portugal) - Tenerife (Spain), from 5 to 10 January, Tenerife - Praia (Cape Verde) from 13 to 19 January, and across the Atlantic from Cape Verde to Rio de Janeiro (Brasil), from January 22nd to February 14th, will be presented and discussed.</span></p>

Observational Data: Overview and Fundamentals

2017 ◽  
Author(s):  
Sarbani Basu ◽  
William J. Chaplin
Keyword(s):  
Time Series ◽  
Magnetic Activity ◽  
The Other ◽  
Doppler Velocity ◽  
Near Surface ◽  
Photometric Observations ◽  
Typical Data ◽  
Observational Technique ◽  
Surface Convection ◽  
Basic Content

This chapter considers some of the fundamentals associated with the basic datasets from which the asteroseismic and other intrinsic stellar parameters are extracted (usually lightcurves of photometric observations or time series of Doppler velocity observations). In particular, the chapter looks at how the observational technique affects the amplitudes of the observed oscillations. It also introduces the other intrinsic stellar signals that manifest in the data, specifically those due to granulation (signatures of near-surface convection) and magnetic activity. The chapter's aim is to familiarize the reader with the basic content of the typical data and lay some important groundwork for the detailed presentations that follow in the next two chapters.

Distribution, origin, and hydraulic influence of fractures in a clay-rich glacial deposit

1995 ◽  
Vol 32 (6) ◽  
pp. 957-975 ◽  
Author(s):  
L.D. McKay ◽  
J. Fredericia
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Flow ◽  
Key Words ◽  
Water Table ◽  
Stress Relief ◽  
Fracture Density ◽  
Lacustrine Environment ◽  
Tritium Content ◽  
Glacial Deposit ◽  
A Site

In the unconsolidated clay-rich glacial deposits underlying a site in southwestern Ontario, fractures and root casts greatly influence hydraulic conductivity and groundwater flow. The fractures are predominantly vertical and have visible oxidation staining from surface to a depth of 6 m. Root casts commonly occur along fracture surfaces in the upper 3 m, but can also occur as holes in apparently unfractured blocks. The fractures are believed caused mainly by dessication during past periods of low water table. This hypothesis is supported by a decrease in fracture density with depth and the presence of a stiff crust, presumably caused by desiccation-induced consolidation. The random pebble fabric and faint layering indicate deposition in a calm lacustrine environment, which precludes the possibility of the fractures having been caused by overriding ice. Fractures were found below the depth of oxidation staining (6 m) but most of these appear to have been caused by stress-relief due to the excavation and subsequent drying. In the upper 3 m the fractures and root casts are responsible for field-measured hydraulic conductivity values that are up to 3 orders of magnitude greater than measured in the laboratory for samples of the unfractured matrix. High values of field-measured hydraulic conductivity, seasonal head variations greater than 0.5 m, and high tritium content all persist below the depth of root casts, indicating that hydraulically conductive fractures do exist to depths of at least 6 m and possibly as great as 12–15 m, which is well below the depth of oxidation staining. However, there is some uncertainty in this assessment of the extent of hydraulically conductive fractures because of the sensitivity to small leaks in the piezometer installations. Key words : clay, glacial, fractures, desiccation, hydraulic conductivity.

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