Hydrogeology Related Glossary/Definitions

(Last update: 7/27/2008)



§    Absorption - solute soaks into matrix 

§    Abstraction – another way of saying “extraction” of groundwater?

§  Accuracy -   Accuracy is hitting the bulls eye of the target. Accuracy is telling the truth . . . Precision is telling the same story over and over again.  Precision is clustering elsewhere on the target.

§  Activity – Can be thought of as an ‘effective’ concentration and is used in connection with liquid and solid phases

§  Activity Coefficient - the ratio of the chemical activity of any substance to its molar concentration. (ratio of effective molar conc to actual conc)?

§  Activity Product – if eqn. 2-8 is not at equilibrium then the expression on the left is the Activity Product

§  Aerobic - oxygen is present, Describes organisms requiring oxygen to live or environments where oxygen is present.

§  Adsorption - solute adheres to exterior of matrix

§  Adsorption – the formation of a layer of gas, liquid, or solid on the surface of a solid or, less frequently, of a liquid.

§  Advective  - 1. The transfer of a property of the atmosphere, such as  heat, cold, or  humidity, by the horizontal  movement of  an  air  mass:

2. The rate of change of an atmospheric property caused by  the  horizontal  movement of air

3. The horizontal movement of water,  as in an ocean  current

§  Advection - the flowing of water in response to a pressure (head)  gradient 

§  Advective Transport - when fluid particles that are distinguishable  move at the avg seepage velocity  

§  Algorithm – a step-by-step procedure for solving a problem or accomplishing some end especially by a computer

§  Alkalinity - the excess of conservative cation equivalents over conservative anion equivalents;  the excess of hydroxide ions (pH > 7); Alkalinity is a measure of the buffering capacity of water, or the capacity of bases to neutralize acids; the number of millequivalents of hydrogen ion that is neutralized by one liter of seawater at 20C;  the capacity of a system to neutralize acid.

§  Amplitude - max displacement from equilibrium

§  Anaerobic - Oxygen is not present.  Describes organism not requiring oxygen to live or environments where oxygen is not present.  

§  Analytical Solution - can be done on a calculator

§  Angular frequency – number of radians per time, or 2π/τ 

§  Anion – A negatively charged ion, i.e. an ion that is attracted to the anode in electrolysis

§  Anisotropy - the condition under which one or more of the hydraulic properties of an aquifer vary according to direction of flow.

§  Annotated Bibliography - An annotated bibliography is a list of papers with abstracts.

§  Annulus - The space between concentric objects, in this case pipe and rock.  The gravel pack area. (Oilfield glossary on web)

§  Anthropogenic – of, relating to, or resulting from the infleunce of human beings on nature.

§  Aquiclude - contains water that does not move (as in shale)

§  Aquifer - usable quantities of water

§  Aquifuge – impervious

§  Aquitard - semipervious, water moves slowly compared to an aquifer

§  Artesian aquifer - a confined aquifer which is under enough pressure to cause the water level in a drilled hole to rise above the confining layer (not above the ground?)  If the water level rises above the ground, it is called a “flowing artesian well”.

§  Aspect ratio -  = wellscreen aspect ratio = length/radius

§  ASR – aquifer storage and recovery system

§  Asymptotic The term asymptotic means approaching a value or curve arbitrarily closely (i.e., as some sort of limit is taken). A line or curve A that is asymptotic to given curve C is the asymptote of C

§  Biodegradation - decay caused by light, temperature, humidity, and microorganisms.

§  Bivalent Ions – Having a valency of two.

§  Boundary Conditions - (see description in 208? formula sheet)  ; Knowledge of h on the aquifer boundaries and throughout the aquifer at a known time (called initial and boundary conditions)

§  Boussinesq Assumptioin -  ρ (density of water?) is constant with time & space

§  Brackish water – water too saline to be potable, but significantly less saline than seawater. 1,000mg/l<TDS <20,000mg/l

§  Brine – waters significantly more saline than seawater

§  BTEX – a mixture of organic compounds including benzene, toluene, ethyl benzene, and xylene (“Applied Contaminant Transport Modeling”)

§  Bulk Modulus (K) - the ratio of the change in pressure acting on a volume to the fractional change in volume. The bulk modulus is a measure of the incompressibility of the material:  K-ΔP/Δ where Δ = (Vt – Vo)/ Vo  (when stress is same in all directions), in units of N/m2.  From Oilfield Glossary: The ratio of stress to strain, abbreviated as k. The bulk modulus is an elastic constant equal to the applied stress divided by the ratio of the change in volume to the original volume of a body, K=∆ρ(∆V/V) ρ=stress, V=volume.

§  Calcification subhumid to arid, rainfall insufficient to drive ions to water table, so CaCO3 builds up at some level depending on rainfall

§  Cation a positively charge ion, i.e. an ion that is attracted to the cathode in electrolysis.

§  Colluviam - the products of gravity-driven mass movement

§  Chelates – Complex involving multidentate legands

§  Complex – a dissolved species formed from two or more simpler species, each of which can exist in aqueous solution, pg 34

§  Components – a group of entities such that every species in the system can be written as the product of a reaction involving only the other components.(pg.17)

§  Compressibility of water - For each atmosphere increase in pressure, the volume of water would decrease 46.4 parts per million (Data from Sears,Zemansky, Young and Freedman, University Physics, 10th Ed., Section 11-6. )

§  Conjunctive Use - Combined use of surface and ground water systems to optimize resource use and minimize adverse effects of using a single source.

§  Connate – water trapped in sediment during deposition

§  Conservative Ions – Ions whose concentration are not affected by pH, pressure, temperature

§  Convolution – the output you get from a continuously varying input.

§  Cooper-Jacob Equation -

§  Damped Natural Frequency – (also called damping frequency?)  the frequency at which a damped system will oscillate in a free vibration situation. ωn = ωd/sqrt(1-ζ2)

§  Damping Coefficient - used to represent how quickly as oscillations amplitude decreases.  Coefficient of zero means no decrease…to 1 which means no oscillations?????  underdamped. “The ratio of absorbed acoustic energy to incident acoustic energy” http://zone.ni.com/devzone/nidzgloss.nsf/webmain/E33425D1931B44D08625686A0078B75D.  Use  http://www.chem.mtu.edu/~tbco/cm416/qsecord_2k1.html to match curve to find damping constant.

§  Damping ratio – (ζ) (same as damping coefficient?)  can be calc’d by finding % overshoot (OS).  Damping Ratio (ζ) = - log(OS/100)/sqrt2+(log(OS/100))2),  OS=100(peak-ss)/ss,  use the 1st max or min just after the slug as zero, ss is the steady state value (from oscillation glossary www.me.cmu.edu/ctms/modeling/tutorial/systemidentification/content.htm

§  Darcy’s Law – Discharge D = –KA(h/l), except when the Reynolds number exceeds about 10.

§  Decomposition - The process that makes a substance more stable in its current environment

§  Delta Nitrate (NO3) - mg/L,  This parameter, used in the instantaneous reaction model, is one component of the total biodegradation capacity of the  groundwater as it flows through the source zone and contaminant plume. The model assumes that 4.9 mg of nitrate are required to consume 1 mg of BTEX. Note that this parameter is used for the instantaneous reaction model, which is appropriate only for readily biodegradable compounds such as BTEX that degrade according to the assumed BIOSCREEN utilization factors, and is not appropriate for more recalcitrant compounds such as the chlorinated solvents.  Typical values, data from 28 AFCEE sites (see Table 1):  Median =  6.3 mg/L,  Maximum = 69.7 mg/L,  Minimum = 0 mg/L. For planning studies, typical values taken from Table 1 can be used.  For actual RNA studies, the Air Force Intrinsic Remediation Technical Protocol should be applied.  Enter the average background concentration of nitrate minus the lowest observed concentration of nitrate in the source area. 

§  Delta Oxygen (O2) - mg/L,  This parameter, used in the instantaneous reaction model, is one component of the total biodegradation capacity of the groundwater as it flows through the source zone and contaminant plume. The model assumes that 3.14 mg of oxygen are required to consume 1 mg of dissolved hydrocarbons .  Note that this parameter is used for the instantaneous reaction model, which is only appropriate for readily biodegradable compounds such as BTEX and probably not appropriate for more recalcitrant compounds such as the chlorinated solvents.  Typ values are data from 28 AFCEE sites (see Table 1):  Median =  5.8  mg/L,  Maximum = 12.7 mg/L,  Minimum = 0.4 mg/L.  For planning studies, typical values taken from Table 1 can be used.  For actual RNA studies, the Air Force Intrinsic Remediation Technical Protocol  should be applied.   

§  Delta Sulfate (SO4), mg/L, This parameter, used in the instantaneous reaction model, is one component of the total biodegradation capacity of the groundwater as it flows through the source zone and contaminant plume. The model assumes that 4.7 mg of sulfate are required to consume 1 mg of BTEX. Note that this parameter is used for the instantaneous reaction model, which is appropriate only for readily biodegradable compounds such as BTEX that degrade according to the assumed BIOSCREEN utilization factors, and is not appropriate for more recalcitrant compounds such as the  chlorinated solvents.  Typical values, data from 28 AFCEE sites (see Table 1):Median =  24.6 mg/L,  Maximum = 109.2 mg/L,  Minimum = 0 mg/L. For planning studies, typical values taken from Table 1 can be used.  For actual RNA studies, the Air Force Intrinsic Remediation Technical Protocol should be applied.  Enter the average background concentration of sulfate minus the lowest observed concentration of sulfate in the source area.  BIOSCREEN then computes a biodegradation capacity. 

§  Density of water – changes with temperature and pressure.  It is most dense around 39F (append 14 in Fetter). Density changes proportionally with change in pressure (Fetter pg68)

§  Detrital – mineral/sediment/rocks derived from transport of solid grains from preexisting rocks

§  Diffusion -   movement of molecules from higher concentration to lower concentration in response to a concentration  gradient

§  Diffusion Coefficient - it is not an intrinsic property of an aquifer,   L2/time.  Usually so small it will usually not be a factor  (except when there is no advective flow) 

§  Dissolved Plume Half-life (t½) - yrs,  Time, in years, for dissolved plume concentrations to decay by one half as contaminants migrate through the aquifer.  Note that the amount of degradation that occurs is related to the time the contaminants spend in the aquifer, and that the degradation IS NOT  related to the time it takes for the source concentrations to decay by half.  Modelers using the first‑order decay model typically use the first‑order decay coefficient as a calibration parameter, and adjust the decay coefficient until the model results match field data.  With this approach, uncertainty in a number of parameters (e.g., dispersion, sorption, biodegradation) are lumped together in a single calibration parameter. Considerable care must be exercised in the selection of a first‑order decay coefficient for each COC in order to avoid significantly over‑predicting or under‑predicting actual decay   rates. Typ values are:  Benzene 0.02  to 2.0 yrs,  Toluene 0.02  to 0.17 yrs,  Ethylbenzene 0.016 to 0.62 yrs, Xylene 0.038 to 1 yrs.  Various published    references are available listing decay half‑life values for hydrolysis and biodegradation.

§  Dispersion -   An apparent diffusion that is the result of advective flow going through particles.  The solute particles take different flow paths which results in a spreading out of contaminants.   It is so much like diffusion  that we use a diffusion  coefficient. Depends on rock or sediment, & gw  flow velocity. 

§  Dispersive Transport - it can be viewed as a method of adjusting  the advective transport calculation for the recognized  deficiencies in the description of the velocity field  (hydrodynamic dispersion).  (Addresses the effects of the individual particle velocities from the average seepage velocity?)

§  Dispersivity - is as is hydraulic conductivity is to Darcy’s Law?    It is a  property of the porous material alone, represents avg spacing of  heterogeneities in rock, sediment, or soil. A fundamental   transport property of porous medium. Controls spreading of contaminant caused by flowing gw.  To estimate, just take 10%   of the ‘scale of  interest’ (10% of distance from source). It is scale dependent - as scale increases, it increases. It is the  proportionality constant in the eqn DL=L v.  Dave says it is  difficult to define.  It is that property of an aquifer that causes  spreading.  L

§  Dispersivity (Bioscreen definition) - Dispersion refers to the process whereby a plume will spread out in a longitudinal direction (along the direction of groundwater flow), transversely (perpendicular to groundwater flow), and vertically downwards due to mechanical mixing in the aquifer and chemical diffusion.  Selection of dispersivity values is a difficult process, given the impracticability of measuring dispersion in the field.  However, simple estimation techniques based on the length of the plume or distance to the measurement point ("scale") are available from a compilation of field test data.  Note that researchers indicate that dispersivity values can range over 2‑3 orders of magnitude for a given value of plume length or distance to measurement point.  It is typically estimated (dispersivity is difficult to measure and field data are rarely collected) using the following methods:   L =   0.1 Lp,  T = 0.33 L,  Z  = 0.05  L   or  Z = 0.025 L to 0.1 L   (values can be estimated at 5 – 10% of the plume length??)     

§  Derivative - The derivative of a function expresses its rate of change   with respect to an independent variable. The derivative is  also the slope of the tangent line to the curve

§  Dry deposition – uptake of gases and very small aerosol particles by vegetation and wety surfaces,, and sedimentation and impaction of larger aerosol particles.

§  Effective Porosity - Dimensionless ratio of the volume of interconnected voids to the bulk volume of the aquifer matrix.  Note that "total porosity" is the oids (included non‑connected voids) to the bulk volume of the aquifer matrix.  Difference between total and effective porosity reflect lithologic controls on pore structure.  In unconsolidated sediments coarser than silt size, effective porosity can be less than total porosity by 2‑5%  (e.g. 0.28 vs, 0.30) , It is typically estimated.  Typ values are: Clay 0.01 ‑ 0.20, Sandstone 0.005 ‑ 0.10,  Silt 0.01 ‑ 0.30,  Unfract. Limestone 0.001‑  0.05,  Fine Sand  0.10 ‑ 0.30,  Fract. Granite 0.00005 ‑ 0.01,  Medium Sand 0.15 ‑ 0.30,  Coarse Sand 0.20  ‑ 0.35,  Gravel 0.10 ‑ 0.35.  Typically  estimated.  One commonly used value for silts and sands is an effective porosity of 0.25.  The ASTM RBCA Standard (ASTM, 1995) includes a  default value of 0.38 (to be used primarily for unconsolidated deposits).

§  Elastic Storage - ?? (Black and Kipp 1981)

§  Electrolyte - is a substance which dissociates free ions when dissolved (or molten), to produce an electrically conductive medium. Because they generally consist of ions in solution, electrolytes known as ionic solutes.  They are sometimes referred to in abbreviated jargon as lytes.  Electrolytes generally exist as acids, bases or salts.

§  Eluviated - the removal of material by leaching (either by solution or suspension) from the upper soil horizons

§  Enthalpy (H) – heat content

§  Entropy (S) – is related to disorder (reduction in chemical potential = increase in entropy)

§  Eolian - pertaining to the wind

§  Ephemeral – lasting a short time; transient

§  Equilibrium thermodynamics – what a system would look like if complete equilibrium were attained (pg.17)

§  Equivalents (eq) – are moles multiplied by ionic charge

§  ERF(x) – the error function, encountered in integrating the normal distribution.  The function gives the probability that a measurement under the influence of accidental errors has a distance less than x from the average value at the center.

§  ERFC(x) – the complementary error function:  erfc (x) = 1-erf (x)

§  Euclidian distance - The distance between two points in Euclidian space. Euclidian dimensions are all orthogonal to each other (they are all at right angles to each other) and refer to physical space.

§  exp  -   exp x = eX

§  Extensive – quantities such as Gibbs Free energy (see intensive); A quantity in a macroscopic system that is proportional to the size of the system.  Examples of extensive variables include volume, mass, and total energy. If an extensive variable is divided by an arbitrary extensive variable, such as the volume, an intensive variable results.  A macroscopic system can be described by one extensive variable and a set of intensive variables.

§  Felsic rock – igneous rock having abundant light colored minerals; also, applied to those minerals (quartz, feldspar, feldspathoids, muscovite) as a group.  It is the complement of mafic.

§  First Order Reaction - (per chemistry dictionary) The sum of the powers of the concentrations is the overall order of the reaction.  For instance, in a reaction: A + B C the rate equation may have the form R = k [A] [B]2, this reaction would be described as 1st order in A and 2nd order in B.  The overall order is three.

§  First Order Decay Coefficient (- lambda) - 1/yr,  Rate coefficient describing first‑order decay process for dissolved constituents.  The first‑order decay  coefficient equals 0.693 divided by the half‑life of the contaminant in groundwater.  In BIOSCREEN, the first‑order decay process assumes that the rate of biodegradation depends only on the concentration of the contaminant and the rate coefficient.  For example, consider 3 mg/L benzene dissolved in water in a beaker.  If the half‑life of the benzene in the beaker is 728 days, then the concentration of benzene 728 days from now will be 1.5 mg/L  (ignoring volatilization and other losses).Considerable care must be exercised in the selection of a first‑order decay coefficient for each constituent in order to avoid significantly over‑predicting or under‑predicting actual decay rates.  Note that the amount of degradation that occurs is related to the time the contaminants spend in the aquifer, and that this parameter is not related to the time it takes for the source concentrations to decay by half.  Typ  values are 0.1 to 36 yr‑1  (see half‑life values).  Find values in various published references are available listing decay half‑life values for hydrolysis  and biodegradation.  Note that many references report the half‑lives; these values can be converted to the first‑order decay coefficients using k =  0.693 / t1/2 (see dissolved plume half‑life).

§  Flow net – a graphical solution to the 2D GWFE, that can give you head, flow rate, gradient, etc. (if you know K). They are a good & quick way to get an initial picture. (Dr. Evans, October 23, 2002) 

§  Fluid Continuum - ??

§  Flux – a flowing of fluid; the rate of transfer of a fluid;

§  Fourier Analysis - The technique of transforming a complex waveform into its sinusoidal components is called Fourier analysis. (Wikipedia)

§  Fourier Transform – the mathematically rigorous operation which transforms from the time domain to the frequency domain and vice versa?? (def from a vibration glossary)

§  Formation water – water in geologic formation (may or may not be connate)

§  Forward Model - Tell me mass of earth and I will tell you the position of a falling object, i.e. you know everything about the world and can therefore predict what you will observe.

§  Fresh water – sufficiently dilute to be potable, TDS<1,000mg/l

§  Fraction Organic Carbon (foc)- unitless,  Fraction of the aquifer soil matrix comprised of natural organic carbon in uncontaminated areas.  More natural  organic carbon means higher adsorption of organic constituents on the aquifer matrix.  Typical values are 0.0002 ‑ 0.02.  The fraction organic carbon  value should be measured if possible by collecting a sample of aquifer material from an uncontaminated zone and performing a laboratory analysis . If unknown, a default value of 0.001 is often used

§  Frequency – number of cycles per time, usually cycles/sec or Hertz. According to http://hyperphysics.phy-astr.gsu.edu/hbase/sound/sound.html#c1,Frequency = 1 / period. See also “resonant frequency”

§  Freundlich Isotherm - (see isotherm) assumes that the solid matrix has infinite sorption capacity, so that the sorbed concentration increases indefinitely with the solute concentration.  C* is an exponential function of C.

§  Frigipan - Brittle subsurface restricting soil horizon, usually loamy textured and weakly cemented.  A natural subsurface horizon with very low organic matter, high bulk density and/or high mechanical strength relative to overlying and underlying horizons; has hard or very hard consistence (seemingly cemented) when dry, but showing a moderate to weak brittleness when moist. The layer typically has redoximorphic features, is slowly or very slowly permeable to water, is considered to be root restricting, and usually has few to many bleached, roughly vertical planes which are faces of coarse or very coarse polyhedrons or prisms.

§  Fugacity – Can be thought of as ‘effective’ pressure, and is used in connection with gases. At the Earth’s surface, the difference between partial pressure & fugacity can be ignored.

§  Gibbs Free energy (G) – the measure of energy in a system

§  Gley - soils subject to periodic or permanent waterlogging, and to some extent displaying the mottled horizon below the surface layer typical of gleying 

§  Hardness – the conc. of ions in water that will react with a sodium to precipitate an insoluble residue. It is usually reported as milligrams per liter of equivalent CaCO3.

§  Heterogeneity - different characteristic in different locations

§  Harmonics -  also called a harmonic series, are components of a spectrum which are integral multiples of the fundamental frequency. A harmonic series in a spectrum is the result of a periodic signal in the waveform. Harmonic series are very common in spectra of machinery vibration.  (def from a vibration glossary)

§  Homogenous  - identical characteristics everywhere - but K may be different in different directions.  K is independent of position.

§  Humus - Organic matter (of vegetable or animal origin) in the soil

§  Hooke’s Law -  (deals with elastic compressibility)

§  Hydraulic Conductivity - Horizontal hydraulic conductivity of the saturated porous medium. Typ values Clays: <1x10‑6 cm/s, Silts: 1x10‑6  ‑ 1x10‑3cm/s  Silty sands: 1x10‑5  ‑ 1x10‑1 cm/s,  Clean sands: 1x10‑3  ‑ 1  cm/s,  Gravels: > 1 cm/s.  Found by using pump tests or slug tests at the site.  It is strongly recommended that actual site data be used for most RNA studies.  Rule of thumb: x = preferred direction, y = 1/10 of x, z = 1/100 of x.

§  Hydraulic Conductivity - indicates the ability of the aquifer material to conduct water through it.  It is the combined property of the medium and the fluid.

§  Hydraulic Diffusivity   a property of an aquifer or confining bed defined as the ratio of the transmissivity to the storativity (http://www.brown.edu/Courses/GE0158/web2_revised/webglossary/hdef/hydraulicdiffusivity.html) ( in my 208 modeling class it was defined as T/S??)

§  Hydraulic Gradient - The slope of the potentiometric surface.  In unconfined aquifers, this is equivalent to the slope of the water table. Typ values are  0.0001 ‑ 0.05 ft/ft, Calculated by constructing potentiometric surface maps using static water level data from monitoring wells and estimating the     slope of the potentiometric surface.  The Vertical Gradient uses the vertical distance between screens, and usually is minor.

§  Hyporheic zone – The zone that experiences exchange with a stream on a reasonably short time scale (such as its bed & bank)

§  Hydroylsis  a chemical reaction of a compound with water.

§  Ion – an atom or group of atoms that has either lost one or more electrons, making it positively charged (cation), or gained one or more electrons, making it negatively charged (anion).

§  Ion Activity Product – (see activity product)

§  Incongruent Solution - ???

§  Illuvial - Having to do with water transport??

§  Illuviation - the process by which material removed in suspension or solution from the upper part of a soil is washed down and deposited in the lower  layers

§  Intensive – quantities such as temperature, chemical potential, etc (see extensive); A quantity in a macroscopic system that has a well defined value at every point inside the system and that remains (nearly) constant when the size of the system is increased. Examples are pressure, temperature, density, specific heat capacity at constant volume, and viscosity.

§  Immiscible Fluid – a fluid that does not easily mix, such as oil & water.

§  Intrinsic Permeability – is representative of the properties of the porous medium alone.  It is basically a function of the size of the openings through which the fluid moves (Fetter pg83). Range from high friction (10-6) to low friction (103) values

§  Inverse Model - Tell me the position of the falling object and I will tell you the mass of the earth.  Inverse problems (answers?) are never unique. In exploration geophysics we always want to solve the inverse model, to find the earth property.  To do an inverse model requires a previous solution to the forward problem.

§  Isopiestic Surface – same as piezometric surface

§  Isotherm - a plot of the sorbed concentration C*, versus the dissolved concentration C of a chemical solution. (at constant temperature). Isotherms are adsorption relationships between the adsorbing species and the solid surface.  Isotherm - a plot of C* vs C .

§  Isothermal conditions - ?? (Black and Kipp 1981)

§  Isotope - are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table.

§  Isotropic  - hydraulic properties of the aquifer are equal in all directions.  K is independent of direction.

§  Iterative -  involving repetition….is a repetition of a process, particularly in a math calculation

§  Jacob Equation – was the first to derive the GWFE (ground water flow equation) 1940

§  Jacob straight-line method - A graphical method using semilogarithmic paper and the Theis equation for evaluating the results of a pumping test.

§  Juvenile water – water’s first appearance such as volcanic water

§  Karst - related to areas where much of the drainage is underground in caverns, sinkholes, underground rivers, etc. Often limestone.

§  Labile – (kinetically labile), complexes that form and decompose rapidly in response to changes in solution composition.

§  Laplace transform   is an integral transform perhaps second only to the Fourier transform in its utility in solving physical problems. The Laplace transform is particularly useful in solving linear ordinary differential equations such as those arising in the analysis of electronic circuits

§  Langmuir Isotherm - (see isotherm, and Freundlich isotherm) allows for a maximum sorption capacity. A non-linear isotherm with a max. value for C*

§  Least Squares – a mathematical procedure for finding the best-fitting curve to a given set of points by minimizing the sum of the squares of the offsets ("the residuals") of the points from the curve. The sum of the squares of the offsets is used instead of the offset absolute values because this allows the residuals to be treated as a continuous differentiable quantity. However, because squares of the offsets are used, outlying points can have a disproportionate effect on the fit, a property which may or may not be desirable depending on the problem at hand.

§  Ligand – (???)

§  Leakage Factor - is the root of the product of the Transmissivity of the aquifer and the resistance of the semipervious layer (pg 8)

§  Line source - for the purpose of simplifying a problem, used to indicate something (pulses or??) start at one infitisibly small line  (what is mathematical relevance?)

§  Linear Isotherm - (see isotherm) is when slope = 1 = b ?

§  Longitudinal wave – see P-waves

§  Love wave - A Love wave is a surface wave having a horizontal motion that is transverse (or perpendicular) to the direction the wave is traveling. (USGS)

§  Numerical Dispersion  - particles moving at different speed. This  causes problems for the Euleran model.  “The  apparent but artificial spreading of solute mass  over time and distance resulting from averaging over finite  volumes”

§  Mass Flux -  a mass flowing of fluid?; the rate of transfer of a mass of fluid?;

§  Matrix – see tensor

§  Meteoric Water – from the atmosphere

§  Miscible – capable of being mixed

§  Model Area Length and Width, ft, Physical dimensions of the rectangular area to be modeled.  If one is interested in concentrations at some particular point along the centerline of the plume, enter this value in the "Modeled Area Length". If one are interested in more accurate mass calculations, make sure most of the plume is within the zone delineated by the Modeled Area Length and Width.  Typical values are 10 to 1000 ft.  Values should be slightly larger than the final plume dimensions or should extend to the point of concern. 

§  Molality – (see Molal Unit)

§  Molal unit (m) – moles of solute per kg of solvent

§  Molarity – (see Molar Unit),  this is now commonly simply called ‘concentration’

§  Molar unit (M) – measures conc in moles of solute per liter of solution

§  Mole fraction – number of moles of ‘A’ in some unit of solution divided by the total number of moles in that unit

§  Mole – a substances formula weight expressed in grams

§  Molecular Dispersion - (see diffusion?)

§  Monod-kinetics - commonly used kinetic expression for describing the  degradation of a particular substrate by microorganisms

§  Moving Average -  A way to eliminate some of the ‘noise’ or clutter in a data set by taking an average at each point based on values behind and forward and averaging them and then moving forward and doing the same thing repeatedly. And then graphing the new results.  Used to ‘smooth’ results in order to better see any underlying trends.

§  Multidentate – when a legand has more than one site by which they can bond to a metal ion

§  Nabla - , also called “del” used to denote the gradient and other vector derivatives.   denotes Laplacian or vector Laplacian.

§  NAPL – non-aqueous phase liquid (full strength contaminants that have not mixed with water yet?)

§  Natural Attenuation - letting the microbes do the work themselves

§  Natural Frequency – The frequency of oscillation of the free vibration of a system if no damping were present. For a single-degree-of-freedom system, the natural frequency where k is the spring constant and m is the mass. To convert between damped and undamped natural frequencies use the damping ratio and this formula: ωn = ωd/sqrt(1-ζ2)

§  Nominal – a given value vs a measured value, i.e. “for the circuit with a nominal resistance of 100kΩ, the measured resistance was 98.3kΩ.”

§  Observed Ferrous Iron (Fe) - mg/L, This parameter, used in the instantaneous reaction model, is one component of the total biodegradation capacity of  the groundwater as it flows through the source zone and contaminant plume. Ferrous iron is a metabolic by‑product of the anaerobic reaction where   solid ferric iron is used as an electron acceptor.  The model assumes that 21.8 mg of ferrous iron represents the consumption of 1 mg of BTEX . Note   that this parameter is used for the instantaneous reaction model, which is appropriate only for readily biodegradable compounds such as BTEX that degrade according to the assumed BIOSCREEN utilization factors, and is not appropriate for more recalcitrant compounds such as the chlorinated solvents. Because ferrous iron reacts with the sulfide produced from the reduction of sulfate, some or most of the ferrous iron may not be observed during groundwater sampling.  Some researchers suspect that the observed ferrous iron concentration is much less (10% or less) than the actual amount of ferrous iron that has been generated due to the sorption of ferrous iron onto the aquifer matrix .  If this is the case, then the value used for this parameter should be much higher than the observed maximum concentration of ferrous iron in the aquifer.  Typical values, data from 28 AFCEE sites (see Table 1):  Median =  16.6 mg/L,  Maximum = 599.5 mg/L,  Minimum = 0 mg/L.  For planning studies, typical values taken from Table 1 can be used.  For actual RNA studies, the Air Force Intrinsic Remediation Technical Protocol should be applied.  Enter the average observed concentration,  in mg/L, of ferrous (dissolved) iron found in the source area (approximately the area where ferrous iron has been observed in monitoring wells)

§  Observed Methane (CH4), mg/L, This parameter, used in the instantaneous reaction model, is one component of the total biodegradation capacity of the  groundwater as it flows through the source zone and contaminant plume. Methane is a metabolic by‑product of methanogenic activity.  The model   assumes that 0.78 mg of methane represents the consumption of 1 mg of BTEX.  Note that this parameter is used for the instantaneous reaction model, which is appropriate only for readily biodegradable compounds such as BTEX that degrade according to the assumed BIOSCREEN utilization factors,  and is not appropriate for more recalcitrant compounds such as the chlorinated solvents.  Typical values, data from 28 AFCEE sites (see Table 1):  Median =  7.2 mg/L,  Maximum = 48.4 mg/L,  Minimum = 0.0 mg/L.  For planning studies, typical values taken from Table 1 can be used.  For actual  intrinsic remediation studies, the Air Force Intrinsic Remediation Technical Protocol  should be applied.  Enter the average observed concentration, in mg/L, of methane found in the source area (approximately the area where methane is observed in monitoring wells). 

§  Occult deposition – more general than ‘dry deposition’ in that it includes deposition by mist & fog

§  Olerian - Olerian coordinate system uses particle tracking system that converts back at the ‘end of the day’?

§  Organic Carbon Partition Coefficient (Koc) - (mg/kg)/(mg/L) or (mg/g) or (L/mg),  Chemical‑specific partition coefficient between soil organic carbon and the aqueous phase.  Larger values indicate greater affinity of contaminants for the organic carbon fraction of soil.  This value is chemical specific and  can be found in chemical reference books. Note that many users of BIOSCREEN will be simulating BTEX as a single constituent.  In this case, either an average value for the BTEX compounds can be used, or it can be assumed that all of the BTEX compounds have the same mobility as  benzene (the constituent with the highest potential risk to human health).  Typical values:  Benzene 38  L/kg,  Ethylbenzene 95 L/kg,  Toluene 135  L/kg,  Xylene 240 L/kg  (Note that there is a wide range of reported values; for example, Mercer and Cohen (1990) report a Koc for benzene of 83  L/kg.)   Can be found in chemical reference literature or relationships between Koc and solubility or Koc and the octanol‑water partition coefficient   (Kow).

§  Oxidation State (or number) – This is a measure of the electron control that an atom has in a compound compared to the atom in the pure element.  An oxidation number consists of two parts: 1) Its sign, which indicates whether the control has increased (neg) or decreased (pos) 2) Its value, which gives the number of electrons over which control has changed.

§  P wave – “primary wave”,  also called longitudinal waves.  They are compressional.

§  Partial Derivative  - (find good definition) Partial derivatives are defined as derivatives of a function of multiple variables when all but the variable of interest are held fixed during the differentiation,   h`(x,y) = x2 + y2  =>   ∂h/∂x = 2x,  ∂h/∂y = 2y. Partial derivatives are defined as derivatives of a function of multiple variables when all but the variable of interest are held fixed during the differentiation. (see http://mathworld.wolfram.com/PartialDerivative.html)

§  Particle - for use in this book (Geology 227), a particle is an ensemble of many molecules contained in a small volume

§  Perennial -  present all seasons of the year

§  Period – is the length of one complete cycle.  See:  http://hyperphysics.phy-astr.gsu.edu/hbase/sound/sound.html#c1

§  Permeability - The ability, or measurement of a rock's ability, to transmit fluids, typically measured in darcies or millidarcies (from the “Oilfield Glossary”). The ability of a material (generally an earth material) to transmit water through its pores when subjected to pressure or a difference in head. Expressed in units of volume of water per unit time per cross-sectional area of material for a given hydraulic head. (http://ag.arizona.edu/AZWATER/reference/glossary/permeab.html)

§  Phreatic aquifer – also called unconfined or groundwater aquifer

§  Phase shift - The phase shift describes how far to the left or right the wave slides. (from http://id.mind.net/~zona/mstm/physics/waves/introduction/introductionWaves.html).  I think the phase shift in sinusoidal testing is just the travel time from the stressed well to the target well??? The change in phase of a periodic signal with respect to a reference.  (http://www.its.bldrdoc.gov/fs-1037/dir-027/_3976.htm)

§  Phreatic surface – surface on which the pressure is atmospheric (water table)

§  Phreatic zone – area below water table

§  Piper diagram – see appendix I in Drever for detailed explanation.

§  Plume Length (estimated) Lp - Estimated length of the existing or hypothetical groundwater plume being modeled.  This is a key parameter as it is generally used to estimate the dispersivity terms (dispersivity is difficult to measure and field data are rarely collected).  Typ values are: for BTEX  plumes,   50 ‑ 500 ft.  For chlorinated solvents, 50 to 1000 ft.  If trying to predict the maximum extent of plume migration, use one of the two methods  below.1) Use seepage velocity, retardation factor, and simulation time to estimate plume length.  While this may underestimate the plume length for a non‑degrading solute, it may overestimate the plume length for either the first‑order decay model or instantaneous reaction model if biodegradation is  significant.2) Estimate a plume length, run the model, determine how long the plume is predicted to become (this will vary depending on the type of  kinetic expression that is used), reenter this value, and then rerun the model. Note

§  Point source -  for the purpose of simplifying a problem, used to indicate something (pulses or??) start at one infitisibly small point  (what is mathematical relevance?)

§  Poisson Ratio - (unitless?) A rod-like specimen subjected to uniaxial tension will exhibit some shrinkage in the lateral direction for most materials. The ratio of lateral strain and axial strain is defined as Poisson's ratio, (per book, the ratio of perpendicular strain ε1 to ‘inline’ strain ε3 ). V = - єyy/єxx The Poisson ratio for most metals falls between 0.25 to 0.35. Rubber has a Poisson ratio close to 0.5 and is therefore almost incompressible. Theoretical materials with a Poisson ratio of exactly 0.5 are truly incompressible, since the sum of all their strains leads to a zero volume change. Cork, on the other hand, has a Poisson ratio close to zero. This makes cork function well as a bottle stopper, since an axially-loaded cork will not swell laterally to resist bottle insertion. The Poisson's ratio is bounded by two theoretical limits: it must be greater than –1,  and less than or equal to 0.5, -1< v ≤ ½,  The proof for this stems from the fact that E, G, and K are all positive and mutually dependent. However, it is rare to encounter engineering materials with negative Poisson ratios. Most materials will fall in the range, 0 ≤ v ≤ ½. From oilfield glossary: An elastic constant that is a measure of the compressibility of material perpendicular to applied stress, or the ratio of latitudinal to longitudinal strain. This elastic constant is named for Simeon Poisson (1781 to 1840), a French mathematician. Poisson's ratio can be expressed in terms of properties that can be measured in the field, including velocities of P-waves and S-waves as shown below. Note that if VS = 0, then Poisson's ratio equals 1/2, indicating either a fluid, because shear waves do not pass through fluids, or a material that maintains constant volume regardless of stress, also known as an ideal incompressible material. VS approaching zero is characteristic of a gas reservoir. Poisson's ratio for carbonate rocks is ~ 0.3, for sandstones ~0.2, and above 0.3 for shale. The Poisson's ratio of coal is ~ 0.4. Cooper used 0.25 in his 1965 article.

§  Polar form – polar coordinates (r,θ), where r is the distance of the point from the origin and θ is the angle, in radians, from the positive x-axis to the ray connecting the origin to the point

§  Porosity - The % of volume that consists of openings or pores.  Clay-45-55%, silt-35-50%, sand-25-40%, gravel-25-40%, sand & gravel-10-35%, glacial till-10-25%, sandstone-5-30%, limestone/dolomite-1-20%, shale-0-10%, fractured crystalline rock-0-10%, vesicular basalt-10-50%, dense solid rack.

§  Precision – Precision is clustering on the target. Accuracy is telling the truth . . . Precision is telling the same story over and over again. 

§  Pressure - is the force per unit area applied on a surface in a direction perpendicular to that surface.  (from Wikipedia free encyclopedia)

§  Push-Pull Test – A push-pull test involves the injection (“push”) of a prepared test solution into an aquifer followed by the extraction (“pull”) of the test solution/groundwater mixture from the same location.  Tests may be performed in existing monitoring wells or multilevel samplers. I assume duration is in minutes or hours??

§  Rayleigh wave - A Rayleigh wave is a seismic surface wave causing the ground to shake in an elliptical motion, with no transverse, or perpendicular, motion (USGS). A Rayleigh wave produces both dilation and vertical motion (Cooper 1965)

§  Resonance - When a forcing frequency is the same as a resonant frequency of the structure, the structure is said to be in resonance.

§  Resonant frequency – An example is the frequency of the underdamped wave after a slug test.

§  Retardation Factor (R) - unitless, The rate at which dissolved contaminants moving through an aquifer can be reduced by sorption of contaminants to the solid aquifer matrix.  The degree of retardation depends on both aquifer and constituent properties.  The retardation factor is the ratio of the groundwater seepage velocity to the rate that organic chemicals migrate in the groundwater.  A retardation value of 2 indicates that if the groundwater seepage velocity is 100 ft/yr, then the organic chemicals migrate at approximately 50 ft/yr. Typ values are 1 to 2 (for BTEX in typical shallow aquifers).  It is usually estimated from soil and chemical data using variables described below (b = bulk density, n = porosity, Koc = octanol‑water partition  coefficient, Kd = distribution coefficient, and foc = fraction organic carbon on uncontaminated soil) with the following expression: R=1+ (Kd*b)/n,  where Kd = Koc * foc.  In some cases, the retardation factor can be estimated by comparing the length of a plume affected by adsorption (such as the benzene plume) with the length of plume that is not affected by adsorption (such as chloride).  Most plumes do not have both types of contaminants, so it is more common to use the estimation technique (Note added later: Retardation factor see screen #27, Chloride 1.0, Benzene 1.3-2.5, TCE 1.1-2, PCE 2-5, lead 5-50, Uranium >100-10000)

§  Reynold’s Number – (Re) – Dimensionless number expressing the ratio of inertial to viscous forces, is used as a criterion to distinguish between laminar & turbulent flow.  Darcy’s Law is valid up to a Reynolds number between 1 and 10.

§  Rigidity Modulus - The rigidity modulus refers to the change of shape produced by a tangential stress.  The rigidity modulus is also referred to as the shear modulus. To convert GPa to Pa multiply by 109  (per book, the ratio of the shear stress to the shear strain)

§  RMS   The root-mean-square (RMS) of a variate X, sometimes called the quadratic mean, is the square root of the mean squared value of x: Physical scientists often use the term root-mean-square as a synonym for standard deviation when they refer to the square root of the mean squared deviation of a signal from a given baseline or fit. The root mean square is a measure of the magnitude of a set of numbers. It gives a sense for the typical size of the numbers. For example, consider this set of numbers:-2, 5, -8, 9, -4. We could compute the average, but this doesn't tell us much because the negative values cancel the positive values, leaving an average of zero. What  we want is the size of the numbers without regard for positive or negative. The easiest way to do this is to just erase the signs and compute the average of the new set:2, 5, 8, 9, 4,Average = 5.6But ... that's not how statisticians decided to do it. For reasons of their convenience, they chose a different approach. Instead of wiping out the signs, they square every number (which makes them all positive), then take the square root of the average.

§  S waves – also called transverse waves.  The particles move back and forth perpendicular to the direction of propagation. An S wave can not travel through a liquid.

§  Salvate - ?? no definition found!!

§  Saline – water with salinity similar to or greater than seawater (35,000mg/l TDS)

§  Scalar  - only has one direction.  A scalar may be considered a zero-rank tensor.  It is a single number unrelated to any axis of reference.

§  Second Order – if a system oscillates it is 2nd order

§  Seepage Velocity - Actual interstitial groundwater velocity, equaling Darcy velocity divided by effective porosity.  Note that the Domenico model and  BIOSCREEN are not formulated to simulate the effects of chemical diffusion.  Therefore, contaminant transport through very slow hydrogeologic  regimes (e.g., clays and slurry walls) should probably not be modeled using BIOSCREEN unless the effects of chemical diffusion are proven to be insignificant.  Domenico and Schwartz (1990) indicate that chemical diffusion is insignificant for Peclet numbers (seepage velocity times median  pore size divided by the bulk diffusion coefficient) > 100.  Typ values are 0.5 to 200 ft/yr.  Calculated by multiplying hydraulic conductivity by hydraulic gradient and dividing by effective porosity.  It is strongly recommended that actual site data be used for hydraulic conductivity and hydraulic gradient data parameters; effective porosity can be estimated.

§  Seismic wave - A seismic wave is an elastic wave generated by an impulse such as an earthquake or an explosion. Seismic waves may travel either along or near the earth's surface (Rayleigh and Love waves) or through the earth's interior (P and S waves).  (USGS)

§  Sensitivity Analysis – A procedure to determine the sensitivity of the outcomes of an alternative to changes in its parameters (as opposed to changes in the environment; see contingency analysis, a fortiori analysis). If a small change in a parameter results in relatively large changes in the outcomes, the outcomes are said to be sensitive to that parameter. This may mean that the parameter has to be determined very accurately or that the alternative has to be redesigned for low sensitivity. (http://pespmc1.vub.ac.be/ASC/SENSIT_ANALY.html)

§  Shape Factor - K = kC (d10)2, where C is the shape factor coefficient: very fine to fine sand is 40-80, medium to coarse sand poorly sorted is 80-120,coarse sand well sorted is 120-150, and  d10 is the grain size in cm

§  Shear modulus (μ or G), in units of pressure? The shear modulus G, is defined as the ratio of shear stress to engineering shear strain on the loading plane. The shear modulus G is also known as the rigidity modulus, and is equivalent to the 2nd Lamé constant m mentioned in books on continuum theory. Common sense and the 2nd Law of Thermodynamics require that a positive shear stress leads to a positive shear strain. Therefore, the shear modulus G is required to be nonnegative for all materials. Oilfield glossary: An elastic constant for the ratio of shear stress to shear strain. The shear modulus is one of the Lame constants. It can be expressed mathematically as follows:  μ=(∆F/A)/(∆L/L), F=shear stress, A=area, L=shear displacement, ∆L=dist between shearing planes

§  Short-screen – This is an expression from Zlotnik (1998).  I believe he uses it in reference to the double packer slug test in which only a section of a well screen is involved in the test.

§  Simulation Time (t), years, Time for which concentrations are to be calculated.  For steady‑state simulations, enter a large value (i.e., 1000 years would be  sufficient for most sites).  Typical values are 1 to 1000 years.  To match an existing plume, estimate the time between the original release and the date the field data were collected.  To predict the maximum extent of plume migration, increase the simulation time until the plume no longer increases in length.

§  Sine Wave - The most familiar AC waveform is the sine wave, which derives its name from the fact that the current or voltage varies with the sine of the elapsed time. Others types of waves include square wave, sawtooth wave, etc.

§  Skin Factor – A numerical value used to analytically model the difference from the pressure drop predicted by Darcy's law due to skin. Typical values for the skin factor range from -6 for an infinite-conductivity massive hydraulic fracture to more than 100 for a poorly executed gravel pack. This value is highly dependent on the value of kh (he product of formation permeability, k, and producing formation thickness, h, in a producing well, referred to as kh) . For example, a 20-psi [138-kPa] total pressure drop related to skin effect could produce almost any skin factor, depending on the value of kh. For any given pressure drop from skin effect, the skin factor increases proportionally as kh increases. (from the Oilfield Glossary)

§  Soil Bulk Density (rho b, b) - kg/L, g/cm3,  Bulk density, in kg/L, of the aquifer matrix (related to porosity and pure solids density).  Although this value can be measured in the lab, in most cases estimated values are used.  A default value of 1.7 kg/L is used frequently.  Source of Data Either from an analysis of soil samples at a geotechnical lab or more commonly, application of estimated values such as 1.7 kg/L.

§  Solubility Product – is an equilibrium constant for a simple solubility rxn

§  Soluble Mass in NAPL, Soil - kg, The best estimate of dissolvable organics in the source zone is obtained by adding the mass of dissolvable organics on  soils, free‑phase NAPLs, and residual NAPLs.  This quantity is used to estimate the rate that the source zone concentration declines.  Note that this is an experimental and unverified model that should be applied with care (the model probably underpredicts removal rate).For gasoline or JP‑4 spills,  BTEX is usually assumed to comprise the bulk of dissolvable organics in the source zone.  To simulate a declining source, use the method described  below.  For constant‑source simulations, either enter a very large number for soluble mass in the source zone (e.g., 1,000,000 kg) or type "Infinite".  Typical Values are 0.1 to 100,000 kg.  This information will most likely come from either: 1) Estimates of the mass of spilled fuel (remember to  convert the total mass of spilled fuel to the dissolvable mass; for example BTEX represents only 5‑15% of the total mass of gasoline). 2) Integration  of maps showing contaminated soil zones (data in mg/kg) and/or NAPL zones (usually product thickness).  The user should estimate the volume of  contaminated soil, convert to kg of contaminated soil, and multiply by the average soil concentration.  To make the estimate more accurate, the user might have to divide the soil into different zones of soil concentrations, into unsaturated vs. saturated soil, and/or into different depths.  (One standard  approach is to divide into a vertically averaged unsaturated zone map and a vertically averaged saturated zone map.)  If the user is making estimates  from NAPL data, remember the thickness of product in a aquifer is only 10‑50% of the actual product thickness in the well 

§  Solute – the substance dissolved in a solvent in forming a solution.

§  Solution - doing a derivation on a given equation to make it into a  form  that is easy to see is true. (?)  A solution is an eqn that  satisfies the equality and  boundary conditions.

§  Sorption - is the combination of both adsorption and absorption

§  Source Thickness in Saturated Zone (z), ft, The Domenico (1987) model assumes a vertical plane source with constant concentration.  For many fuel  spill sites the thickness of this source zone is only 5 ‑ 20 ft as petroleum fuels are LNAPLs (light non‑aqueous phase liquids) that float on the water table.  Therefore, the residual source zones that are slowly dissolving, creating the dissolved BTEX plume, are typically restricted to the upper part of the aquifer. Typical Values are 5‑50 ft.  This value is usually determined by evaluating groundwater data from wells near the source zone screened at  different depths.  If this type of information is not available, then one could estimate the amount of water table fluctuation that has occurred since the time of the release and use this value as the source zone thickness (equating to the smear zone).  Otherwise, a simple assumption of 10 feet would  probably be appropriate for many petroleum release sites.  Note that if DNAPLs are present at the site (e.g., a chlorinated solvent site) larger source zone thicknesses would probably be required.

§  Source Zone - The source zone is typically defined as being the area with contaminated soils having high concentrations of sorbed organics, free‑phase   NAPLs, or residual NAPLs.  If the source zone covers a large area, it is best to choose the most downgradient or widest point in the source area to draw the perpendicular‑to‑flow line.

§  Source Zone concentration - mg/L, BIOSCREEN requires source zone concentrations that correspond to the source zone width data. Suggested rules of  thumb regarding how to handle multiple constituents are:1)  If the maximum plume length is desired, model lumped constituents (such as BTEX).  If a  risk assessment is being performed, data on individual constituents are needed, .2)  If lumped constituents are being modeled (BTEX all together), use  either average values for the chemical‑specific data (Koc and lambda) or the worst‑case values (e.g., use the lowest of the Koc and lambda from the group of constituents being modeled) to overestimate concentrations.  Most modeling will be performed assuming that the ratio of BTEX at the edge of  the plume is the same as at the source.  For more detailed modeling studies,  the following rules of thumb to help account for different rates of reaction  among the BTEX compounds: if the site is dominated by aerobic degradation (most of the biodegradation capacity is from oxygen, a relatively rare  occurrence) assume that the benzene will degrade first and that the dissolved material at the edge of the plume is primarily TEX.  If the site is  dominated by nitrate utilization (most of the biodegradation capacity is from nitrate, a relatively rare occurrence) assume that benzene will degrade last and that the dissolved material at the edge of the plume is primarily benzene.  If the site is dominated by sulfate reduction (most of the biodegradation  capacity is due to sulfate utilization, a more common occurrence) assume that the benzene will degrade  at the same rate as the TEX constituents and that the dissolved material at the edge of the plume is a mixture of BTEX.  If the site is dominated by methane production (most of the biodegradation  capacity is due to methanogenesis, a more common occurrence) assume that benzene will degrade last and that the dissolved material at the edge of the  plume is primarily benzene.3)  If individual constituents are being modeled with the instantaneous reaction assumption, note that the total biodegradation capacity must be reduced to account for electron acceptor utilization by other constituents present in the plume.  For example, in order to model benzene as an individual constituent using the instantaneous reaction model in a BTEX plume containing equal source concentrations of  benzene, toluene, ethylbenzene and xylene, the amount of oxygen, nitrate, sulfate, iron, and methane should be reduced by 75% to account for  utilization by toluene, ethylbenzene, and xylene.  Typical Values are 0.010 to 120 mg/L.  Source of data is the source area monitoring well data.

§  Source Zone Width - The Domenico (1987) model assumes a vertical plane source of constant concentration.  BIOSCREEN expands the simple one source‑zone approach by allowing up to five source zones with different concentrations.  This allows one to account for spatial variations in the source area. Typical Values are 10 ‑ 200 ft.

§  Species – a chemical entity: ion, molecule, solid phase, etc

§  Specific Capacity (SC) – is the yield or discharge of the well divided by the drawdown of the well at that specific discharge.  gpm/ft of dd.  This was in “HydroVisions” Summer 2005, vol 14, no.2

§  Specific Discharge (q) – The flow rate (velocity) thru a measurable area (?).  an apparent velocity calculated from Darcy's law; represents the flow rate at which water would flow in an aquifer if the aquifer were an open conduit (rather than traveling around sand particles). Also called Darcy Flux and Darcy Velocity. 

§  Specific Retention - affects storativity in an unconfined aquifer but not in a confined aquifer

§  Specific Storage (SS) – in L-1, This is also called the elastic storage coefficient.  Usually only applies to confined aquifers (specific yield is the equivalent for unconfined aquifers?). The amount of water released from or taken into storage per unit volume of a porous medium per unit change in head. Also known as the compressibility factor.  Normal values are 0.0001 ft -1 or less. Units are length -1.  SS will always be<0.0001 ft-1 in confined aquifer per Dave lecture 10-16-02.  S = SS  • b (or storativity divided by screen length. http://www.twdb.state.tx.us/gam/czwx_s/cw_report.pdf)

§  Specific Yield (SY) - This applies more to unconfined aquifers? Units are %.   Normal values are similar in range to storativity.  Also, it is similar in some ways to effective porosity. Driscall - Clay 1-10%, sand 10-30%, gravel 15-30%, sandstone 5-15%, shale 0.5-5%, limestone 0.5-5%,  sometimes used to describe the storativity (or specific storage) of an unconfined aquifer. Per Fetter, “The ratio of the volume of water a rock or soil will yield by gravity drainage to the volume of the rock or soil.  Gravity drainage may take several months to occur.”

§  Standard entropy – entropy = zero?

§  Standard Enthalpy of formation – represents the enthalpy (heat) change when 1 mole of a species is formed from its constituent elements (in standard state)

§  Standard Free energy of formation – the free energy change when 1 mole of the species in its standard state is formed from the elements of which it is composed.

§  Storage coefficient (S) – see storativity

§  Storativity (S) –dimensionless (also coefficient of storage) (from 127, Storativity=specific storage x aquifer thickness). The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head. It is dimensionless.  It is equal to the product of specific storage and aquifer thickness.  It is more relevant in confined aquifers. In an unconfined aquifer, the storativity is equivalent to the specific yield. It indicates relationship between change in quantity of water stored and corresponding change in head. Normal values are 0.02 to 0.03.  Storativity can be obtained from an aquifer test and working backward from matching the Theis Curve.  Driscoll says unconfined aquifer range from 0.01 to 0.3, and confined aquifer range from 10 -5 to 10–3 . Dave said in 10-16-02 lecture, “S=Ss x b, usually 0.00001<SS<0.001 in confined aquifer. S is of interest due to how it changes when moving water (by pumping?).”   Larger number means more water is available?  Values derived from observations of multi-well tests (Dr. T. Brikowski, UTD).

§  Stiff diagram - see appendix I in Drever for detailed explanation.

§  Strain – Small changes in length and volume associated with deformation of the earth by tectonic stresses or by the passage of seismic waves (per book “…the resultant change in shape (from the application of stress)).  Per lecture, there is a linear relationship between stress & strain.  Per lecture, E is the proportionality constant.

§  Stress - Force per unit area acting on a plane within a body (per book “a given force divided by the area over which it is applied). Six values are required to characterize completely the stress at a point: three normal components and three shear components.

§  Surface wave – is a seismic wave trapped near the surface of the Earth.  (USGS)

§  System – represents a group of chemicals we wish to consider (pg.17)

§   System Taylor Series – A Taylor series is a series expansion of a function about a point. A one-dimensional Taylor series is an expansion of a real function f(x) about a point x = a is given by: ex=ea[1+(x-a)+1/2(x-a)2+1/6(x-a)3+…]

§  Tensor  - has magnitude that depends on direction;  tensors are used to rotate vectors in anisotropic material.  A first rank tensor (vector) is specified by 3 numbers, each of which is associated with one of the axis of reference.  A second-rank tensor is specified by 9 numbers, each of which is associated with a pair of axis.  The K tensor in 2 dimensions has a 4 value matrix, in 3 dimension has a 9 value matrix. Because K is a symmetrical tensor, we have 6 different values in a 9 value matrix and 3 different values in a 4 value matrix. Per Dave, you can think of tensor & matrix as synonymous.

§  TDS – total dissolved solids

§  Theis equation – an equation for the flow of ground water in a fully confined aquifer.

§  Theis type curve -A plot on logarithmic paper of well function W(u) as a function of 1/(u

§  Thiem equation – for steady-state flow in a confined aquifer.  One pumping well and one piezometer. (find list of assumptions elsewhere)

§  Tidal method – is a simple method of determining diffusivity (T/S) based on the response of an aquifer to tidal forces at a boundary. (the attenuation of the wave as it propagates into the aquifer)

§  Time Series - Time series analysis accounts for the fact that data points taken over time may have an internal structure (such as autocorrelation, trend or seasonal variation) that should be accounted for. From Dave, a series of data that varies with time.

§  Tortuosity -  The actual length of a ground-water path, which is sinuous in form, divided by the straight-line distance between the ends of the flow path. Tortuosity (τ) = n 1/3 Schwartz  Fund. of G.W.pg449, τ = le/l  (long route over straight route) per Dave Evans 9-16-03. to correct velocity use: Driscoll pg83, GW & Well, actual velocity = measured velocity/ porosity

§  Transient Flow - Transient flow is flow where the flow velocity and pressure is changing with time. Ff Often transient flows persist as oscillating pressure and velocity waves for some time after the initial event that caused it. Transient flow problems are commonly solved using a finite difference method known as the method of characteristics. (from a pipe system design website)

§  Transverse wave – see S-waves

§  Transmissibility  The flow capacity of an aquifer measured in volume per unit time per unit width. Equal to the product of permeability times the saturated thickness of the aquifer. (From U of Arizona http://ag.arizona.edu/AZWATER/reference/glossary/transmis.html.

§  Transmissivity (T) - The rate at which water of a prevailing density and viscosity is transmitted through (i.e. flow per unit width of aquifer per unit hydraulic gradient) a unit width of an aquifer or confining bed under a unit hydraulic gradient. A measure of the amount of water that can be transmitted horizontally through a unit width by the full saturated thickness of the aquifer under a hydraulic gradient of 1. It is a function of properties of the liquid, the porous media, and the thickness of the porous media. Units are l2/t.  It can be obtained from an aquifer test and working backward from matching the Theis Curve. It can be estimated by multiplying K time bed thickness. – indicates aquifers ability to transmit water through its entire thickness (conductivity x thickness). USGS showed results in ft2/day from 45 to 1,000,000 at http://sofia.usgs.gov/publications/wri/90-4108/testsconducted.html.  unconsolidated sand aquifers have values of 5x10-6 to 5x10-2 m2/s –  http://www.utdallas.edu/~brikowi/Teaching/Geohydrology/LectureNotes/Regional_Flow/Transmissivity.html

§  Trilinear diagram – (another name for piper diagram)

§  Unconfined aquifer – an aquifer in which there are no confining beds between the zone of saturation and the surface.  There will be a water table in an unconfined aquifer.

§  Undamped Natural Frequency - The same as the natural frequency of a structure.  (def from a vibration glossary)

§  Unidentate – When  a ligand has only one site by which it can bond to a metal

§  Univalent Ions – Having a valency of one.

§  Vadose zone – area above the water table 

§  Vector  - has magnitude and direction.  A vector may be considered a first-rank tensor.

§   Viscosity -– a measure of the reluctance of a fluid to yield to shear when the fluid is in motion

§  Water Table Aquifer – see “unconfined aquifer”

§  Well filter -  a term used in the Van der Kamp paper (1976) that I think is synonymous with screen or gravel pack

§  Well Loss – the difference in water level between the water inside the wellbore of a well currently being pumped (lower) and the water level just outside the wellbore (higher). (efficiency?)

§  Young’s Modulus  (E) -  (also called Modulus of Elasticity). (a) The measure of the elastic force of any substance, expressed by the ratio of a stress on a given unit of the substance to the accompanying distortion, or strain. (b) An expression of the force (usually in terms of the height in feet or weight in pounds of a column of the same body) which would be necessary to elongate a prismatic body of a transverse section equal to a given unit, as a square inch or foot, to double, or to compress it to half, its original length, were that degree of elongation or compression possible, or within the limits of elasticity; -- called also Young’s modulus.  (Per book, This constant directly relates resultant strain to a given stress… probable that rocks with different values for E will have different velocities)   The modulus of elasticity in tension, also known as Young’s modulus E, is the ratio of stress to strain on the loading plane along the loading direction .  E = σxx / εxx    Common sense (and the 2nd Law of Thermodynamics) indicates that a material under uniaxial tension must elongate in length.  Therefore the Young’s modulus E is required to be non-negative for all materials,  E > 0 (in units of pressure?). From Oilfield Glossary: An elastic constant named after British physicist Thomas Young (1773 to 1829) that is the ratio of longitudinal stress to longitudinal strain and is symbolized by E. It can be expressed mathematically as follows: E=(F/A)/(∆L/L) A=area,F=force,L=length