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. 28 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 stepbystep 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: KΔP/Δ where Δ = (V_{t} – V_{o})/ V_{o }(when stress is same in all
directions), in units of N/m^{2}.
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 gravitydriven 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 116. ) §
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. §
CooperJacob Equation  §
Damped Natural Frequency – (also called damping frequency?) the frequency at which a damped system will
oscillate in a free vibration situation. ω_{n}
= ω_{d}/sqrt(1ζ^{2}) § 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)/sqrt(π^{2}+(log(OS/100))^{2}), OS=100(peakss)/ss, use the 1^{st}
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 (NO_{3})  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 (O_{2})  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 (SO_{4}), 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, L^{2}/time. Usually so small it will usually not be a
factor (except when there is no advective flow) §
Dissolved Plume Halflife (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 D_{L}=_{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) = 1erf (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 = e^{X} § 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 1^{st} order in A and 2^{nd}
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.phyastr.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 CaCO_{3}. §
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^{‑3}cm/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 (10^{3})
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
straightline 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 nonlinear isotherm with a max. value for C* §
Least Squares – a mathematical procedure for finding the
bestfitting 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 Pwaves §
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?) §
Monodkinetics  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 –
nonaqueous 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 singledegreeoffreedom 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: ω_{n} = ω_{d}/sqrt(1ζ^{2}) § 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) = x^{2} + y^{2} =>
∂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.phyastr.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 crosssectional 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/fs1037/dir027/_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 rodlike 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 ε_{1} to ‘inline’ strain ε_{3}
). V =  є_{yy}/є_{xx}_{
}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 axiallyloaded 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 Pwaves
and Swaves as shown below. Note that if V_{S} = 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. V_{S} 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 xaxis to the ray connecting the origin to the point §
Porosity 
The % of volume that consists of openings or pores. Clay4555%, silt3550%, sand2540%,
gravel2540%, sand & gravel1035%, glacial till1025%,
sandstone530%, limestone/dolomite120%, shale010%, fractured crystalline
rock010%, vesicular basalt1050%, 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) §
PushPull Test – A pushpull 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 1.32.5, TCE 1.12, PCE 25,
lead 550, Uranium >10010000) §
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 10^{9 }(per book, the ratio of the shear
stress to the shear strain) §
RMS – The
rootmeansquare (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 rootmeansquare
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 zerorank
tensor. It is a single number
unrelated to any axis of reference. §
Second Order
– if a system oscillates it is 2^{nd} 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 (d_{10})^{2}, where C is
the shape factor coefficient: very fine to fine sand is 4080, medium to coarse
sand poorly sorted is 80120,coarse sand well sorted is 120150, and d_{10} 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 §
Shortscreen
– 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
infiniteconductivity 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 20psi [138kPa] 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 (S_{S}) – 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}. S_{S} will always be<0.0001 ft^{1}
in confined aquifer per Dave lecture 101602. S = S_{S } • b (or storativity divided by screen
length. http://www.twdb.state.tx.us/gam/czwx_s/cw_report.pdf) §
Specific Yield (S_{Y})  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 110%, sand 1030%, gravel 1530%, sandstone 515%, shale 0.55%,
limestone 0.55%, 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
101602 lecture, “S=S_{s }x b, usually 0.00001<S_{S}<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 multiwell 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 onedimensional Taylor series is an expansion of a real function f(x) about a point x = a is given by: ex=e^{a}[1+(xa)+1/2(xa)^{2}+1/6(xa)^{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 secondrank 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 steadystate 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 groundwater path, which is sinuous in form,
divided by the straightline distance between the ends of the flow path.
Tortuosity (τ) = n ^{1/3} Schwartz Fund. of G.W.pg449, τ = l_{e}/l (long route over straight route) per Dave
Evans 91603. 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 Swaves §
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 l^{2}/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 ft^{2}/day
from 45 to 1,000,000 at http://sofia.usgs.gov/publications/wri/904108/testsconducted.html. unconsolidated sand aquifers have values of
5x10^{6} to 5x10^{2} m^{2}/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 firstrank
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 = σ_{xx}
/ ε_{xx}_{ } Common sense (and the 2^{nd} Law of
Thermodynamics) indicates that a material under uniaxial tension must
elongate in length. Therefore the
Young’s modulus E is required to be nonnegative 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 § § 
