Surficial Sources Research Articles

A Note on Exact Closed-Form Solutions for Lamb’s Problem with an Arbitrary Poisson’s Ratio

Abstract Lamb’s Problem, a cornerstone in theoretical seismology, investigates the displacement of an elastic half-space due to surficial or buried point sources. Although the exact closed-form solution for surface displacements from surficial sources is well established, the solutions for buried sources in the 3D case have remained limited, either confined to integral forms or applicable only for certain Poisson’s ratios. This study addresses this gap by generalizing the existing closed-form solutions to accommodate Poisson’s ratio for buried sources. Our solutions are expressed in terms of elementary algebraic expressions, elliptic integrals, and Gauss hypergeometric functions. The derived solution is validated by numerical tests. With the newly derived solution, we also explore the properties of the leaking mode, which stems from the complex conjugate roots of the Rayleigh equation.

Reactive transport modelling the oxalate-carbonate pathway of the Iroko tree; Investigation of calcium and carbon sinks and sources

The oxalate carbonate pathway (OCP) of the Iroko tree has been shown to function as a carbon sink, due to the precipitation of calcium (Ca) carbonate in the tree and the soil around its roots, a soil developed on a carbonate-free bedrock. A 1D reactive transport (RT) model of the Iroko OCP system was constructed and used in a sensitivity analysis to replicate the geochemical pathway of the OCP and carbon sequestration, constrained by the Ca mass balance. The sensitivity analysis examined ranges of contributions for Ca sources to the system, including rainfall, dust, plant decomposition, mineral weathering, and optionally groundwater Ca sources. The study focused on identifying possible scenarios by which the observed magnitude of accumulated soil calcite could be reproduced, related to the OCP geochemical pathway. In line with field observations of the Iroko, all model results showed a soil transition from acidic (pH 5.1) to mildly alkaline (maximum pH 8.1) conditions, as well as precipitation of calcite. The location of calcite precipitation remained within the upper reach of the soil column, and between 29% and 63% of carbon was retained as calcite. The magnitude of calcite precipitation was limited both by the availability of Ca from the various sources, and by the tree’s rate of root water and solute uptake. The sensitivity analysis confirms that surficial sources such as rainfall and dust deposition contribute only a small fraction of Ca, and indicate that mineral weathering and the extent of the root system, must play a dominant role in supplying Ca to facilitate carbon sequestration through calcium carbonate formation.

Assessment of Range of Olfactory Impact of Plant to Mechanical-biological Treatment of Municipal Waste

Plants (installations) to mechanical-biological treatment (MBT) of municipal solid waste belong to the object group being potential sources of odorants emission. One of the most important parameters of their characteristic is the range of the real olfactory impact. It depends on many factors, such as: the type of emitter (point or surficial) and its characteristics (among other things, height and surface, polluted air stream temperature), emission value and its variability in time, and also topography and land management method and local climatological and meteorological conditions. Assessment of range of olfactory impact of plants is the issue, which may be the subject of theoretical considerations. The search for answers for practical purposes is associated among other things with spatial planning (land use), decision-making on location and land management (improvement of the territory) around the MBT installation and resolving complaints and disputes arising from their nuisance for residents (inhabitants). In Poland, the range of onerous impact of waste management facilities has been, in the past, assessed mainly by the indicator method (based on the widths of the so-called protection zone), and currently is determined using mathematical modelling (especially for of planned undertakings) and direct olfactometric measurements (in the case of existing facilities).In the paper is presented a general outline of the methodology of assessment of a range of olfactory impact of fugitive emission from surficial sources. Theoretical considerations are illustrated on the example of the results of the examinations of large plant (installation) of the mechanical-biological treatment of waste. During the examinations, apart from usual odour emission and dispersion processes, the effect of the convective vertical flow of the odorant-polluted air effect was observed.The research program includes twelve series of direct olfactometric measurements (with field olfactometers) and odorimetric observations in measurement-observation (receptor) points, deployed in and around the MBT installation. In each series has been tagged the background of air polluted with odorants (on the windward side of MBT installation). The olfactometric examinations were carried out by method of identification and with characterizing the trail of the odour emitted from the explored source. The receptor points were determined mainly in the area, in which the odours were uniquely identifiable as to their origin. In addition, has been made one “intervention” series of odorimetric observations. During field examinations, olfactometric measurements were carried out with control of the current meteorological situation – measurements and observations of the weather conditions (wind, temperature and relative humidity of the air, the degree of cloudiness).

Evaluation of aquifer recharge and vulnerability in an alluvial lowland using environmental tracers

A multi-layered aquifer system (eastern Po plain, northern Italy) was investigated by means of isotopic data, with the goal of quantifying groundwater recharge from different sources and assessing the intrinsic vulnerability of aquifers to surface sources of contamination. The geology of the area is based on a stratigraphic alternation of several sandy aquifers and silty–clayey aquitards, down to a maximum depth of 200 m b.g.s. Water isotopes (δ18O, δ2H), and hydrochemical analyses were performed on groundwater samples collected from a regional network of 70 boreholes distributed on an area of almost 2000 km2. In addition to the regional sampling, detailed vertical isotopic profiling was performed in one location by means of groundwater and sediment samples collected through the whole sequence of aquifers and aquitards. Water isotopes indicated mixing from different sources of recharge (i.e., vertical recharge, Po river, deeper aquifers). Mixing calculations were used to quantify the contributions to the aquifers from the different sources. The vertical profiling allowed for integrating and validating the interpretations at a regional scale. The recharge pattern defined for the different aquifers was translated into an index of hydrogeologic interconnections with the surface, which represents a physically based proxy of the intrinsic vulnerability of the aquifers to surficial sources of contamination. The investigated setting can be considered to be representative of many other anthropized and groundwater demanding plain settings around the world. Thus, the proposed method represents a valuable approach for such settings both for recharge quantification (e.g., to be used as input for numerical modeling) and for a physically based assessment of the intrinsic vulnerability.

Tracing the origin of fine-grained fluvial sediment using radionuclides with management implications

Abstract This paper reports a study of the origin of fine-grained river sediments and their potential impact to a reservoir that supplies drinking water. Excess sediment may affect water quality and decrease the storage capacity of the reservoir. Three sediment cores were taken in 2011 from the Rockaway River in New Jersey that leads into the reservoir to determine the sources of the sediment and propose remediation actions. The coring sites spanned an area upstream in the watershed to just above the reservoir, and the sites varied in land use. Sediment was analyzed in one to two centimeter intervals to determine the radionuclide activity of excess 210 Pb and 137 Cs. The sediment activity level at two of the sites (the ones farthest up- and downstream) show predominantly low levels of excess 210 Pb and 137 Cs, suggesting that the sediment is coming from deeper sources such as river channel widening/lateral migration and hillslope failures and/or legacy sediment sources. The sediment from site 2 exhibited higher activity of excess 210 Pb, suggesting more surficial sources of sediment or relatively recent sediments and likely tied to widespread urbanization. The different radionuclide profiles between the cores suggest spatial variation in the sediments’ sources, with the sources varying between surficial and deeper ones. Establishing the origin of this sediment would help to derive management solutions to lessen sediment delivery, stabilize and/or remove legacy sediment supplies to minimize downstream impacts.

Fluorescence characteristics and sources of dissolved organic matter for stream water during storm events in a forested mid-Atlantic watershed

[1] The concentrations and quality of dissolved organic matter (DOM) and their sources were studied for multiple storm events collected over a three-year period (2008–10) in a forested headwater (12 ha) catchment in the mid-Atlantic Piedmont region of the USA. DOM constituents were characterized using a suite of indices derived from ultraviolet absorbance and PARAFAC modeling of fluorescence excitation emission matrices. Runoff sources and hydrologic flow paths were identified using an end-member mixing model, stable isotope data, and groundwater elevations from valley-bottom saturated areas. DOM constituents and their sources differed dramatically between base flow and storm-event conditions. The aromatic and humic DOM constituents in stream water increased significantly during storm events and were attributed to the contributions from surficial sources such as throughfall, litter leachate and soil water. Groundwater sources contributed a large fraction of the DOM constituents during base flow and were responsible for the high % protein-like fluorescence observed in base flow. Hydrologic flow paths and runoff sources were critical for explaining the differences in DOM among the storm events. This study underscored the value of studying multiple storm events across a range of hydrologic and seasonal conditions. Summer events produced the highest concentrations for humic and aromatic DOM while the corresponding response for winter events was muted. A large event following summer drought produced a complex DOM response which was not observed for the other events. These extreme events provided important insights into how DOM quality may change for future changes in climate and water quality implications for sensitive coastal ecosystems.

Experimentally identifying masked sources applying time reversal with the selective source reduction method

This paper describes a time reversal (TR) method of spatially illuminating a source signal which has been masked by another source signal. This masking occurs as a result of inherent limitations in the traditional TR process. The selective source reduction (SSR) method employs a subtraction technique where one TR focus is selectively reduced to illuminate the masked focus. Experimental results and considerations are presented to demonstrate the SSR method for two elastic wave pulses emitted simultaneously from two spatially separated surficial sources and to examine the limitations of the method. A blind test was conducted to demonstrate that no a priori information about the source(s) is required. Spatial and/or temporal characteristics of multiple close-proximity sources can be resolved with the use of the illumination method. The measurements show that the SSR method’s limitations are chiefly due to imperfect temporal reconstruction of the source function in the time reversed focal signal, which consequently limits signal reduction.

Effects of daily precipitation and evapotranspiration patterns on flow and VOC transport to groundwater along a watershed flow path.

MTBE and other volatile organic compounds (VOCs) are widely observed in shallow groundwater in the United States, especially in urban areas. Previous studies suggest that the atmosphere and/or nonpoint surficial sources could be responsible for some of those VOCs, especially in areas where there is net recharge to groundwater. However, in semiarid locations where annual potential evapotranspiration can exceed annual precipitation, VOC detections in groundwater can be frequent. VOC transport to groundwater under net discharge conditions has not previously been examined. A numerical model is used here to demonstrate that daily precipitation and evapotranspiration (ET) patterns can have a significant effect on recharge to groundwater, watertable elevations, and VOC transport. Ten-year precipitation/ET scenarios from six sites in the United States are examined using both actual daily observed values and "average" pulsed precipitation. MTBE and tetrachloroethylene transport, including gas-phase diffusion, are considered. The effects of the precipitation/ET scenarios on net recharge and groundwater flow are significant and complicated, especially under low-precipitation conditions when pulsed precipitation can significantly underestimate transport to groundwater. In addition to precipitation and evapotranspiration effects, location of VOC entry into the subsurface within the watershed is important for transport in groundwater. This is caused by groundwater hydraulics at the watershed scale as well as variations in ET within the watershed. The model results indicate that it is important to consider both daily precipitation/ET patterns and location within the watershed in order to interpret VOC occurrence in groundwater, especially in low-precipitation settings.

New Jersey's water supply demand and needs

This paper discusses the needs in the New Jersey water supply infrastructure, which are necessary to provide safe drinking water over the next 20 years. Three aspects of the state's water system—resources, treatment, and distribution—are investigated. The latest data on water withdrawals are provided on three different bases: statewide, by county, and by aquifer for both surficial and groundwater sources. Recommendations are made on both product delivery and system performance levels. The available data suggest that, at present, there is an ample supply of good quality water in the state of New Jersey but that State's regulations and monitoring must be strengthened as well as scientific research and remediation of existing polluted areas boosted.

Martian hillside gullies and icelandic analogs

We report observations of Icelandic hillside gully systems that are near duplicates of gullies observed on high-latitude martian hillsides. The best Icelandic analogs involve basaltic talus slopes at the angle of repose, with gully formation by debris flows initiated by ground water saturation, and/or by drainage of water from upslope cliffs. We report not only the existence of Mars analog gullies, but also an erosional sequence of morphologic forms, found both on Mars and in Iceland. The observations support hypotheses calling for creation of martian gullies by aqueous processes. Issues remain whether the water in each case comes only from surficial sources, such as melting of ground ice or snow, or from underground sources such as aquifers that gain surface access in hillsides. Iceland has many examples of the former, but the latter mechanism is not ruled out. Our observations are consistent with the martian debris flow mechanism of F. Costard et al. (2001c, Science 295, 110–113), except that classic debris flows begin at midslope more frequently than on Mars. From morphologic observations, we suggest that some martian hillside gully systems not only involve significant evolution by extended erosive activity, but gully formation may occur in episodes, and the time interval since the last episode is considerably less than the time interval needed to erase the gully through normal martian obliteration processes.

Intensive gas sampling of noble gases and carbon at Vulcano Island (southern Italy)

The helium isotopic ratio of crater, beach and submarine fumaroles, water wells, and soil gases at Vulcano Island has been, since 1987, repeatedly measured. The 3He/4He from crater fumaroles (F5 and FA) oscillates biennially between 4.9 and 6.0–6.2 R/Ra. The periodicity of the 3He/4He oscillation may be linked to pressure variations in a deep gas reservoir. Chemical and carbon isotope variations during the same period closely reflect trends shown by helium. These simultaneous variations, chemical and isotopic, suggest a close relationship between these species and reflect one dominant process, which belong to the routine activity of the volcano. The 40Ar/36Ar ratio up to 1200 is not consistent with the presence of an air‐rich source and suggests the addition of radiogenic argon. Neon data (20Ne/22Ne and 21Ne/22Ne) indicates that a crustal component is present beneath the volcano. Heavy carbon, 0‰ ∼ −2‰, also supports the existence of a crustal component. The isotopic data here obtained do not indicate that the recorded variations (chemical and isotopic) indicate a “period of unrest” at Vulcano Island. The present phase of activity is explained with a two‐state model of the feeding sources of the volcano: (a) a gas release from intermediate and surficial sources and (b) a magmatic pulse, 3He‐rich, from a deep gas reservoir (not migration of magma) which continuously mixes with more surficial fluids. Additions of surficial (air saturated waters) or atmospheric fluids are minor and may occur during the ascent of the gas phase to the surface or, more likely, be added at the time of the gas collection.

Acid rain, a world‐wide phenomenon: a perspective from the united states

The observation that precipitation carries particles and gases to the earth's surface has been a recurrent interest of scientists for more than two hundred years. Since the late 1940s, this interest has been piqued by the observation that rainfall is acidic, and that this acidity results largely from the byproducts of combustion. “Acid rain” occurs over large areas of Europe and North America. Using recent data from a large United States network of collection stations, we show maps of pH, sulfate, nitrate, ammonium, and calcium in precipitation; we also show the results of an analysis of trends in these ions from 1979 to 1986. Sulfate, nitrate, and hydrogen ion concentrations peak in the northeastern United States where anthropogenic emissions of sulfur and nitrogen are highest. Ammonium and calcium ions peak in the central part of the United States, where the combination of biogenic, surficial and anthropogenic sources of these pollutants is highest. Though only calcium trends were statistically signific...

Radon and helium in soil gases in the Phlegraean Fields, central Italy

The distribution and migration of radon and soil‐gas concentrations in the Phlegraean Fields, Italy, are controlled by the tectonic features of the area. Radon is supplied from surficial sources and helium has both surficial and deep origins. There is no direct correlation between the two noble gases on a point‐to‐point basis but the areal distribution of both gases is similar, suggesting that the distribution is controlled primarily by fractures and movement of geothermal fluids.

Evaluation of groundwater replenishment coefficients from the record of a borehole penetrating the unsaturated zone

The coefficients of groundwater replenishment from surficial sources are the most critical parameters in assessing the exploitable yield of an aquifer. So far, the methods used for estimating these coefficients failed to yield plausible results, either because of crude models of the system or because of a simultaneous estimation of many parameters requiring long and diverse data records. This paper proposes a method for obtaining the in situ chronological sequence of the coefficients of replenishment at a given site, independently from the estimates of other parameters. It is based on the profiles of water content and concentrations of tritium and chloride in a single borehole penetrating the unsaturated zone. A combination of these data with the historical record of their inputs at the surface of the ground enables dating of the moisture content in each depth interval. This yields a series of seasonal replenishment coefficients from both natural and anthropogenic sources. The application of the method is illustrated at two sites in the central and southern parts of Israel.

WATER QUALITY PATTERNS DURING A STORM ON A MALL PARKING LOT1

: Intensive temporal sampling of rainfall, surface runoff and subsurface drainage, and stream flow upstream and downstream of a suburban mall parking lot yielded expected patterns in time and space. Variations in temperature and conductivity showed strong dilution effects, while patterns of nine elemental concentrations in surface runoff showed a flushing effect early in the storm, following by dilution. Heavy nitrate loads in surface runoff were apparently from rainfall, not surficial sources. For the magnitude of storm studied and the existing study site, local impact on stream flow and water quality, like the run-off itself, is rather ephemeral, and dissipates after about five hours.

WATER QUALITY PATTERNS DURING A STORM ON A MALL PARKING LOT1

ABSTRACT: Intensive temporal sampling of rainfall, surface runoff and subsurface drainage, and stream flow upstream and downstream of a suburban mall parking lot yielded expected patterns in time and space. Variations in temperature and conductivity showed strong dilution effects, while patterns of nine elemental concentrations in surface runoff showed a flushing effect early in the storm, following by dilution. Heavy nitrate loads in surface runoff were apparently from rainfall, not surficial sources. For the magnitude of storm studied and the existing study site, local impact on stream flow and water quality, like the run‐off itself, is rather ephemeral, and dissipates after about five hours.

A Supergene Origin for Vein-Type Uranium Ores in the Light of the Western Australian Calcrete-Carnotite Deposits

The discovery of a major uranium deposit in the calcretes of Western Australia confirms the economic importance of this type of occurrence. The calcrete is a surficial limestone formed by near-surface groundwater; uranium derived by weathering of nearby granite occurs as carnotite in vugs and fractures in the calcrete. Vanadium has been important in fixing uranium as insoluble carnotite and appears to have been derived from the surrounding laterites. Since the calcretes are unequivocally of surficial and recent origin, the uranium must have been similarily formed.The genetic importance of such surficial processes to the origin of sedimentary deposits of the Colorado type is easily visualized. However, a surficial origin for uranium in pitchblende-vein deposits also satisfactorily explains their spatial and temporal relationships to unconformities and uranium-rich granitic complexes. Vein deposits in the Northern Australia uranium province are good illustrations of the features attributed to surficial sources of uranium in pitchblende-vein deposits.

Artificial Recharge of Treated Waste Waters and Rainfall Runoff into Deep Saline Aquifers of Peninsula of Florida: ABSTRACT

Fast-growing population centers of the state of Florida, mainly in coastal beaches, have imposed large demands on the sources of fresh water. They also threaten to deteriorate the esthetic and recreational value of the area with their waste waters. The largest of these population centers is on the southeastern end of the peninsula of Florida, commonly referred to as the Miami area. The second largest is on the central west coast of the peninsula in the Tampa-St. Petersburg area. The Florida peninsula is underlain by several thousand feet of carbonate rock, with only minor amounts of clastic sediments. Cavernous limestone and dolomite aquifers at relatively shallow depths constitute the principal source of fresh water in the area. Deeper cavernous zones, separated from the freshwater zones by practically impermeable limestone and dolomite, are uniquely suited to receiving injected fluids. Deep-well disposal of waste waters into deep saline aquifers, after secondary biologic treatment and disinfection, is feasible if (1) an aquifer exists that can accept treated waste waters without significant changes in its hydraulic and structural characteristics, and (2) if use of the water in that aquifer, adjacent ones, or from surficial sources is not impaired. Two large disposal wells have been constructed for a private utility in the Miami area of southeast Florida. They are approximately 3,000 ft in depth and recharge an artesian aquifer having chloride concentrations near that of seawater (19,000 mg/l). The receiving aquifer is overlain by a thick aquiclude, by another aquifer (saline but of lower chloride concentration), and then by a thick, impervious section separating the highly mineralized waters from the shallow and fresh groundwater. Three concentric steel casings, cemented at the proper depths, permit injection into the deeper aquifer with protection of the upper strata. Monitoring of the upper saline water-bearing stratum, where any possible leak from the deeper aquifer would normally be first detected, is performed through the annulus between the 2 inner well casings. An integrated water-quality aquisition system continuously monitors the injected waste and provides an alarm and pump shut down if established limitations are exceeded. Operation of the first well for over a year has proved fully reliable, and economically advantageous. Eight similar disposal wells are being considered in the area. On the basis of this experience, a new research program is being implemented to inject, store, and recover when needed, rainfall runoff into the deep saline aquifers of southern Florida. A test-prototype well is presently being constructed within the city of St. Petersburg to determine (1) the characteristics of the deep underground formations; (2) the quality of the deep groundwaters; (3) the injection rate capacity and associated increase in pressure; (4) the ratio of the amount of fresh water that could be subsequently recovered to that injected; and (5) the quality of the recovered water. End_of_Article - Last_Page 1595------------