Front Matter
-
Published:2022
Daniel A. Vallero, Ph.D. "Front Matter", Methods and Calculations in Environmental Physics, Daniel A. Vallero, Ph.D.
Download citation file:
Methods and Calculations in Environmental Physics refreshes and introduces the basics of physics for those trained in other disciplines who apply physics in their work and research. This book examines a range of topical environmental challenges from a physics perspective, addressing them as both forward and inverse problems. Readers are then able to see cause-and-effect relationships from the full range of physical principles and factors.
Comprehensive coverage includes:
An interdisciplinary and systems approach to topics including systems dynamics, toxicology, risk exposure, and pollution control
A focus on many aspects of environmental problems from the perspective of the physicist
Relationships between environmental physics, chemistry, and biology
Methods and Calculations in Environmental Physics is an invaluable resource for practicing environmental enginteers and scientists, graduate students in environmental programs, and undergraduates in engineering, biology, and ecology.
Abbreviations and Symbols
The following abbreviations and symbols are used in this text and/or in cited sources. The list is not completely exhaustive because there is much variability in the use of symbols, especially because air pollution draws from numerous scientific and professional disciplines.
- ηe
effective porosity (dimensionless)
- Ψ
impaction factor (dimensionless)
- σ or σ°
surface tension (forces length−1)
- σy
cross-sectional dispersion coefficient
- σz
dispersion coefficient in the vertical direction
- σ or SD
standard deviation
- σ2
variance
- ζi
mass ratio
- µ
degree of saturation
- µg
microgram
- µm
micron or micrometer
- σn
normal shear stress (mass length−1 time−2)
- Ω
humidity ratio
energy (heat) required for reaction
ordinary derivative of x with respect to y
substrate concentration at the gas/aqueous interface
source mean
- τ
mean residence time
partial derivative of x with respect to y
- [C]
molar concentration
- –
mean or average (capped symbol or letter)
- ∇ (nabla)
gradient of a scalar field, especially in Navier–Stokes equations
- Δ (nabla)
water table
- ≅
approximately equal to
- ≈
almost equal to
- −
single chemical bond
- =
double chemical bond
- ≡
triple chemical bond
- →
kinetic reaction
- ↔
equilibrium reaction
- °C
degrees Celsius or Centigrade (temperature)
- °F
degrees Fahrenheit (temperature)
- K
degrees Kelvin (temperature)
- °lat
latitude (deg)
- °long
longitude (deg)
- °R
degrees Rankine (temperature)
- µ or µv
dynamic viscosity (mass length−1 time−1)
- µ
chemical potential (mass length2 time−2)
- µE
microenvironment (exposure science)
- µg
gas viscosity (mass length−1 time−1)
- µm
arithmetic mean
- µM
micromole
- –
anion (superscript)
- +
cation (superscript)
- 0
initial condition (subscript)
- 1
first (subscript)
- 1,4-D
1,4-dioxane
- A
magnetic vector potential (tesla meter—T m)
- A
area, surface area (length2)
- A
availability (engineering economics)
- a
acceleration
- A
activity rate (in emission calculation)
- A
air (subscript)
- A
amplitude
- A
aqueous phase
- A
atomic mass number
- A
uniform cost
- A/C
air-to-cloth ratio (filtration; length time–1)
- AA
atomic absorption detection
- Aaw
airway surface area (length2)
- abs
absorbed
- AC
activated carbon
- AC
alternating current (electricity)
- ACH
air changes per hour
- ADD
average daily dose
- ADE
average daily exposure
- ADME
absorption, distribution, metabolism and excretion (or elimination)
- ADMET
absorption, distribution, metabolism, excretion and toxicity
- ADP
adenosine diphosphate
- AER
air exchange rate
- AF
absorption or absorption factor
- AF
assessment factor
- AHERA
Asbestos Hazard and Emergency Response Act
- AIRS
Aerometric Information Retrieval System (U.S.)
- Al2(SO4)3
aluminum sulfate (alum)
- ALARP
as low as reasonably practicable (risk)
- amu
atomic mass unit
- Ap
cross-sectional area of the particle (length2) =
- AP
averaging period
- ap
particle acceleration
- aq
aqueous phase
- As
arsenic
- As
exposed body surface area
- As
clarifier tank surface area
- ASCE
American Society of Civil Engineers
- ASME
American Society of Mechanical Engineers
- ASPECT
airborne spectral photometric environmental collection technology
- AT or taveraging
averaging time for exposure
- ATC
allowable threshold concentration
- atm
atmosphere (unit of pressure)
- ATP
adenosine triphosphate
- ATSDR
Agency for Toxic Substances and Disease Registry (U.S.)
- AWQC
ambient water quality criteria
- B
bioavailability factor (exposure)
- B(a)P
benzo(a)pyrene
- BCA
benefit–cost analysis
- B/C or BCR
benefit-to-cost ratio
- BACT
best available control technology
- BAF
bioaccumulation factor
- BCF
bioconcentration factor
- BCR
benefit/cost ratio
- BDL
below detection limit
- BF
bioavailability (percent of substance absorbed per day)
- BMD
benchmark dose
- BMP
best management practices
- BNA
base-neutral and acid extractable organics
- BOD
biochemical oxygen demand
- BTEX
benzene, toluene, ethylbenzene and xylenes (indication of gasoline contamination)
- Btu or BTU
British Thermal Unit (power) = 1060 J
- BW
body weight (mass)
- C
coulomb (ampere second—A s)
- C
chemical concentration ([mass mass−1], [volume volume−1] or [mass volume−1])
- C
heat capacity (J K−1)
- Ca
airborne chemical concentration (mass volume−1 of air in breathing zone)
time-weighted concentration
- c
speed of light (299 792 458 m s−1)
- C
specific heat capacity (J kg−1 K−1)
- cal
calorie
- Cc
Cunningham slip correction factor
- CCR
coal combustion residuals
- Cd
cadmium
- CD
drag coefficient (dimensionless)
- CDC
Centers for Disease Control and Prevention (U.S.)
- CDD
chlorinated dibenzodioxin
- CDE
carbon dioxide equivalents
- CDF
chlorinated dibenzofuran
- CERCLA
Comprehensive Environmental Response, Compensation and Liability Act (also known as Superfund; U.S.)
- CF
characterization factor (LCA)
- CFC
chlorofluorocarbon
- CFD
computational fluid dynamics
- CFM
cubic feet per minute
- CFR
Code of Federal Regulations (U.S.)
- C6F14
perfluorohexane
- C2H3Cl
vinyl chloride
- CH2F2
difluoromethane (hydrofluorocarbon-32)
- CI
confidence interval
- Ci
curie (radioactivity unit)
- Cij
concentration of exposure by person i in microenvironment j
- CNS
central nervous system
- CO
carbon monoxide
- CO2
carbon dioxide
- CoC
contaminant of concern
- COD
chemical oxygen demand
- COHb
carboxyhemoglobinemia
- COPD
chronic obstructive pulmonary disease
- Corg
substrate organic matter (mass of organic carbon per mass of substrate)
- cos
cosine
- cp
specific heat at constant pressure
- CP
serum concentration
- CPA
critical path analysis
- cps
cycles per second (1 cps = 1 Hz)
- CPM
critical path method
- Cr
chromium
- CS
equilibrium concentration of the solute in the solid phase
- CSF
cancer slope factor [(mass mass−1 time−1)−1] (also SF)
- cv
specific heat at constant volume
- CVD
cardiovascular disease
- CxHyOx
organic compound (hypothetical or representative)
- d
day
- d
distance
- d
diameter (length)
- D
electric flux density (coulomb per square meter—C m−2)
- D
dose
- D
index of community diversity
- D
intermedia or intercompartmental transport term (fugacity models)
- D
mass of pollutant per body mass
- D
transfer coefficient or compartmental rate constant (for fugacity)
dispersion tensor (length time−1)
- d0
proportionality constant (diffusion)
- DA
non-diffusive transfer coefficient for fugacity
- DC
diameter of the collection object (length)
- DC
direct current (electricity)
- DCA
dichloroethane
- DD
diffusive transfer coefficient for fugacity
- dB
decibel
- DCE
dichloroethylene
- DDD
2,2-bis(p-chlorophenyl)-1,1-dichloroethane
- DDE
dichlorodiphenyldichloroethylene
- DDT
1,1,1- trichloro-2,2-bis(p- chlorophenyl)ethane
- di
percentage difference (precision)
- DI
daily intake
- DIAL
differential absorption lidar
- dL
deciliter (volume)
- DNA
deoxyribonucleic acid
- DNAPL
dense (high density) nonaqueous phase liquid
- DNEL
derived no-effect level
- DO
dissolved oxygen
- DOAS
differential optical absorption spectroscopy
- DP
degradation product
- Df
Feret's particle diameter
- Dm
Martin's particle diameter
- dp
physical particle diameter (length)
- Dpa or dpa
aerodynamic diameter of a particle (length)
- Dps or dps
Stokes particle diameter (length)
- DQO
data quality objective
- DRE
destruction and removal efficiency
- DRL
differential rate law
- DTW
depth to water
- DU
Dobson unit (ozone)
- E
electric field
- e
eccentricity
- e
charge of electron (4.8 × 10-10 statcoulombs)
- E
electrical field strength (potential; voltage length-1).
- E
bulk modulus (fluid stress divided by strain)
- E
emission
- E
energy required in a reaction
- e
Euler's number = 2.71828183…
- E
evaporative flux
- E
event (probability and statistics)
- E
exposure
- E
particle collection efficiency; inverse of penetration (filtration)
- E0
strength of electrical field (volts length-1)
- E/P
evaporation/percolation
- Ea
Arrhenius activation energy
- EC
average exposure concentration
- EC
electrical conductivity
- EC
elemental carbon
- EC50
median effective concentration
- ECD
electron capture detection
- ED
exposure duration (time)
- EDB
ethylene dibromide (1,2-dibromoethane)
- EDC
ethylene dichloride (1,2-dichloroethane)
- ED
exposure dose
- EDS
energy dispersive spectroscopy
- EEC
estimated environmental concentration
- EF
emission factor (in emission calculation)
- EF
exposure frequency (time)
- EF
enrichment factor (biogeochemistry)
- EF
effect factor (LCA)
- EHS
extremely hazardous substance
- EHW
extremely hazardous waste
- Eing
ingestion exposure (mass per time)
- Einh
inhalation exposure (mass per time)
- EIS
environmental impact statement
- EJ
environmental justice
- EL
exposure length (time per time)
- ELCR
excess lifetime cancer risk
- ELF
extremely low frequency
- EMP
elongate mineral particulate
- EMR
electromagnetic radiation
- EPA or U.S. EPA
Environmental Protection Agency (U.S.)
- EPH
extractable petroleum hydrocarbons
- EPS
extracellular polymeric substance
- ER
percent overall emission reduction efficiency (in emission calculation)
- erg
energy and work unit (10−7 joules)
- EROEI
energy return on energy investment
- ESP
electrostatic precipitator
- EUAB
equivalent uniform annual benefit
- EUAC
equivalent uniform annual cost
- EUAW
equivalent uniform annual worth
- exp(x)
exponential (ex)
- Eυ
energy at frequency υ
- F
force
- f
Coriolis parameter
- F
energy flux
- F
favorable
- F
force (mass length time−2)
- F
Faraday constant
- f
frequency (probability and statistics)
- f
friction
- f
fugacity
- f
fugacity (subscript)
- f(x)
function of x
- FB
buoyancy force (mass length time−2)
- FC
centrifugal force (mass length time−2)
- FD
drag force (mass length time−2)
- FE
electrostatic charge (force)
- FDA
Food and Drug Administration (U.S.)
- Fe
iron
- FF
fate factor (LCA)
- FGD
flue gas desulfurization
- FID
flame ionization detection
- FIFRA
Federal Insecticide, Fungicide and Rodenticide Act (U.S.)
- fOC
weight fraction of organic carbon in compartmental matrix (dimensionless)
- FP
flashpoint
- FR
Federal Register (U.S.)
- FS/PA
feasibility study and preliminary assessment (U.S. Superfund)
- ft
foot (length)
- FTIR
Fourier-transform infrared
- g
gas or vapor phase (subscript or parenthetic)
- G
gas-phase emissions (mass time-1)
- G
Gibbs free energy
- G
shear modulus
- g
gram
- g
gravitational force
- G
non-diffusive flow rate (for fugacity)
- G
universal gravitational constant
- g0
standard gravitational field
- GAC
granulated activated carbon
- gal
gallon
- GC
gas chromatography
- gc
gravitational constant =
- GHG
global greenhouse gas
- GHz
gigahertz (109 Hz)
- Gi
advection rate (fugacity models)
- GI
gastrointestinal tract
- GIS
geographic information system
- GLP
good laboratory practice
- GPS
global positioning system
- grad
gradient; grad f = ∇f(x, y) in a plane and ∇f(x, y, z) in space
- GTP
global temperature potential
- GWP
global warming potential
free energy formation at steady state
- H
hazard
- h or hr
hour
- h
elevation
- H
enthalpy
- H
heat (subscript)
- H
Henry's law (subscript) (also KH)
- H
horizontal (subscript)
- h
Planck's constant (6.62 × 10−27 erg s)
- ha
hectare
- HC
hydrocarbon
- hcapillary
rise of the fluid in a capillary
- HEPA
high efficiency particulate air (filter)
- Hg
mercury
- HHM
hierarchical holographic modeling
- HI
hazard index
- HLRW
high-level radioactive waste
- HMIWI
hospital/medical/infectious waste incinerators
- HON
hazardous organic NESHAPs
- hPa
hectopascal (unit of pressure)
- HPLC
high performance liquid chromatography
- HPV
high production volume (chemical class)
- HQ
hazard quotient
- HR
hazard ratio
- HRS
hazard ranking system
- HW
hazardous waste
- HVAC
heating, ventilation and air conditioning
- HYSPLIT
Hybrid Single Particle Lagrangian Integrated Trajectory (model)
- Hz
hertz (cycles s-1)
- hυ
photon
- i
group, species, subgroup of total (subscript)
- i
flow of electrons
- I
immobilized
- I
in situ
- I
intake dose
- I
moment of inertia
- i
intensity
- i
imaginary unit
- ic
concentration gradient
- ICP
inductively coupled plasma detection
- ICR
information collection request
- ICS
Incident Command System
- ID
interior diameter
- IDL
instrument detection limit
- IDLH
immediately dangerous to life and health
- IAEA
International Atomic Energy Agency
- IH
imminent hazard
- in Hg
inches of mercury (unit of pressure)
- IN
mass or energy inflow to control volume; influent (subscript)
- IR
ingestion rate
- IR
infrared
- IRL
integrated rate law
- IPCC
Intergovernmental Panel on Climate Change
- IPM
integrated pest management
- IR
intake rate ([mass time−1] or [volume per time])
- IR
inhalation rate
- IR
infrared
- IR-DIAL
infrared-differential absorption lidar
- IRIS
Integrated Risk Information System
- IRR
internal rate of return
- ISCLT
Industrial Source Complex Long Term (model)
- IUR
inhalation unit risk
- J
joule (energy unit)
- J
flux
- k
Boltzmann's constant (1.37 × 10−16 erg K−1)
- K
kinetic energy
- K
partitioning coefficient
- K
hydraulic conductivity
- k
reaction rate constant
global volumetric mass transfer coefficient (time−1)
- k1
filter media resistance constant
- k2
filter dust cake resistance constant
- Ka
acid equilibrium constant
- KAW
air–water partitioning coefficient
- Kb
base equilibrium constant
- KD
soil sorption partitioning coefficient
- kE
unitless exposure factor
- KF
Freundlich isotherm constant
- kg
kilogram
- KG/A
partition coefficient between the gaseous and the aqueous phases
- KH
Henry's law partitioning coefficient (also H)
- kinh
inhalation rate (volume of air per unit time)
- km
kilometer (length)
- Koa
octanol–air partitioning coefficient
- Koc
organic-carbon partitioning coefficient
- Kow
octanol–water partitioning coefficient
- kp
rate of chemical energy storage by primary producers
- kPa
kilopascal (unit of pressure)
- Km
Michaelis constant (Michaelis–Menton equation)
- Ks
Monod growth rate coefficient
- Ksp
solubility product constant
- Kw
water dissociation equilibrium constant
- kWh
kilowatt-hour
- L or l
liter
- L
angular momentum
- l
liquid phase (subscript or parenthetic)
- LADD
lifetime average daily dose
- LADSCR
lifetime average daily soil contact rate (normalized to bodyweight)
- LADSIR
lifetime average daily soil intake rate (normalized to bodyweight)
- lb
pound (weight)
- lbf
foot-pound (force)
- lbm
international avoirdupois pound (weight)
- LC
liquid chromatography
- LC50
lethal concentration-50 (lethal to 50% of tested organisms)
- LCA
life cycle analysis or life cycle assessment
- LCRA
life cycle risk assessment
- LCI
life cycle inventory
- LD50
lethal dose-50 (lethal to 50% of tested organisms)
- LEL
lower explosive limit
- LEV
low emissions vehicle
- lidar
remote sensing of distance using a laser (combination of light and radar)
- LLWR
low-level radioactive waste
- ln(x)
natural log of x
- LNAPL
light (low density) nonaqueous phase liquid
- LOAEC
lowest observed adverse effect concentration
- LOAEL
lowest observed adverse effect level
- LoC
level of concern
- LoD
limit of detection (also known as DL, detection limit)
- LOEL
lowest-observed-effects-level
- log
logarithm
- LoQ
limit of quantitation
- LOSU
level of scientific understanding
- LPG
liquefied propane gas
- LRTAP
long-range transboundary air pollutants
- LTP
local temperature and pressure
- Lv
distance at which a black object is just barely visible
- m
mass
- m
meter
- M
mole (gram molecular weight)
- M
relatively nonreactive molecule in a reaction
- MA
total soil mass adhered to skin
- MACRS
Modified Accelerated Cost Recovery System
- MACT
maximum achievable control technology
- max
maximum (subscript)
- MCE
mixed cellulose ester
- MCL
maximum contaminant level (drinking water)
- MDL
method detection limit
- Me
metal
- MEI
maximum exposed individual
- MEK
methyl ethyl ketone
- MF
mobilization factor
- MF
modifying factor
- MFAA
millipore cellulose ester membrane
- Mg
magnesium
- mg
mass of displaced gas
- MHz
megahertz (106 Hz)
- MIC
methyl isocyanate
- min
minimum (subscript)
- min
minute (time)
- MIR
maximum individual risk
- mm
millimeter
- mm Hg
millimeters of mercury (unit of pressure)
- mM
millimole
- mmBTU
106 BTU
- MMTCDE
million metric tonnes carbon dioxide equivalents
- MMT
methylcyclopentadienyl manganese tricarbonyl
- mmt
million metric tons
- Mn
manganese
- MOA
mode of action
- MOE
margin of exposure
- mol
mole (gram molecular weight)
- mp
particle mass
- MPN
most probable number (microbes)
- MQO
model quality objective
- MRF
materials recovery facility
- MRL
minimum risk level
- MRT
mean residence time
- MS
mass spectroscopy
- MSAT
mobile source air toxic
- MSDS
material safety data sheet
- MSL
mean sea level
- MSW
municipal solid waste
- MSWLF
municipal solid waste landfill
- MTBE
methyl tertiary-butyl ether
- MTTR
mean time to repair
- MUC
maximum use concentration
- mV
millivolts (potential)
- MW
megawatt
- MW
molecular weight
- n
number of charges (electrostatics)
- N
concentration (number)
- N
Newton (unit of force)
- N
not significant
- n
number (e.g., number of moles)
- N
transport process rate (fugacity × compartmental rate constant)
- N2
molecular nitrogen
- N-100
respirator protection efficiency against particulate aerosols (99.97%), but not resistant to oil
- NA
nonaqueous phase
- NA
non-attainment
- NAA
neutron activation analysis
- NAAQS
National Ambient Air Quality Standard (U.S.)
- NADP
National Atmospheric Deposition Program (U.S.)
- NAPL
nonaqueous phase liquid
- NATA
National Air Toxics Assessment (U.S.)
- ND, n.d.
not detected
- NDIR
nondispersive infrared
- ng
nanogram
- NHANES
National Health and Nutrition Examination Survey (U.S.)
- Nin
number of particles (count) entering a system (e.g., filter)
- Ni
nickel
- NIOSH
National Institute for Occupational Safety and Health
- NIST
National Institute of Standards and Technology (U.S.)
- nM
nanomole
- NMHC
non-methane hydrocarbon
- NMOG
non-methane organic gases
- NMVOC
nonmethane volatile organic compound
- NOAA
National Oceanic and Atmospheric Administration (U.S.)
- NOAEC
no observed adverse effect concentration
- NOAEL
no observed adverse effect level
- NOEL
no-observed-effect-level
- NOHSCP/NCP
National Oil and Hazardous Substances Contingency Plan
- Nout
number of particles (count) exiting a system (e.g., filter)
- NOx
oxides of nitrogen; specifically NO and NO2
- NOy
oxides of nitrogen; specifically NOx and NOz
- NOz
HNO3 + HONO + N2O5 + HO2NO3 + PAN + organic nitrates
- NPDES
National Pollutant Discharge Elimination System (U.S., Clean Water Act)
- NPL
National Priorities List (Superfund)
- NPL
National Physics Laboratory (UK)
- NPP
net primary product (or productivity)
- NR
Reynolds number (also Re)
dimensionless particle Reynolds number
- NRC
Nuclear Regulatory Commission (U.S.)
- NSR
no significant risk
- NTP
National Toxicology Program (U.S.)
- NTP
normal temperature and pressure
- NVOC
nonvolatile organic compound
- O
octanol (subscript)
- O2
molecular oxygen
- O3
ozone
- O&M
operation and maintenance
- OA
organic acid
- OC
organic carbon (subscript)
- OC/EC
organic carbon-to-elemental carbon ratio
- OECD
Organisation for Economic Co-operation and Development
- OMI
ozone monitoring instrument
- OP
organophosphorus (pesticide class)
- OP-FTIR
open-path Fourier transform infrared
- OSC
on-scene coordinator (Superfund)
- OSHA
Occupational Safety and Health Administration (U.S.)
- OUT
mass or energy outflow from control volume; effluent (subscript)
- P
skin permeability coefficient
- P or p
pressure
- p
momentum
- p
partial
- p
particle (subscript)
- P
particle penetration; inverse of efficiency (filtration)
- P
particulate matter emissions (mass time−1)
- P
probability
- P
power
- P
initial cost
- P0
vapor pressure
- P1
net primary productivity (or production)
- P-100
oil-proof respirator protection efficiency against particulate aerosols (99.97%)
- pa
partial pressure of chemical substance gas in inhaled air
- pa
partial pressure of gas a
- Pa
pascal (unit of pressure)
- PA
preliminary assessment
- PAD
population adjusted dose
- PAH
polycyclic aromatic hydrocarbon (sometimes polyaromatic hydrocarbon)
- PAL
point, area and line (model)
- PAL-DS
point, area and line model with deposition and settling
- PAMS
photochemical assessment monitoring station
- Pb
lead
- pb
partial pressure of chemical substance gas in blood
- PBPD
physiologically based pharmacodynamic
- PBPK
physiologically based pharmacokinetic
- PBT
persistent, bioaccumulating and toxic
- PC
particle concentration
- PC
polycarbonate
- PCA
principal component analysis
- PCB
polychlorinated biphenyl
- PCDD/F
pentachlorodibenzodioxins and furans
- PCE
tetrachloroethene
- pCi
picocurie (radioactivity unit)
- PCM
phase contrast microscopy
- PCR
polymerase chain reaction
probability density function
- PEL
permissible exposure limit (OSHA)
- PFAS
per- and polyfluoroalkyl substances
- PFOA
perfluoroctanoic acid
- PFOS
perfluorooctane sulfonate
- pH
negative log of H+ or H3O+ concentration
- Pi
phosphate molecule with high energy bonds
- PIC
product of incomplete combustion
- PID
photoionization detector
- pKa
negative log of the acid dissociation constant
- pL
super-cooled liquid vapor pressure
- PLM
polarized light microscopy
- PM
particulate matter
- PM10
particulate matter, <10-µm diameter
- PM2.5
particulate matter, <2.5-µm diameter
- PMR
proportionate mortality rate
- PNEC
predicted no-effect concentration
- PNS
peripheral nervous system
- POD
point of departure
- pOH
negative log of OH− concentration
- POM
polynuclear organic material
- POP
persistent organic pollutant
- POTW
publicly owned treatment works
- ppb
parts per billion
- ppbV
parts per billion by volume
- PPA
potentially productive aquifer
- PPE
personal protection equipment
- ppm
parts per million
- ppmV
parts per million by volume
- ppt
parts per trillion
- PRP
potentially responsible party (Superfund)
- PQAO
primary quality assurance organization
- PQL
practical quantitation limit
- PRTR
Pollutant Release and Transfer Register (Mexico)
- PSA
particle-size analysis
- PSD
particle-size distribution
- PSF
particle-size fraction
- psi
pounds per square inch (pressure)
- PUF
polyurethane foam
- Pv
velocity pressure
- PV
present value
- PVC
polyvinyl chloride
- Q
flow; volumetric flow rate
- Q
water discharge
- Q
heat passing through boundary
- q
electric charge on a particle
- q
flux
- q1*
cancer slope value (U.S. Cancer Assessment Group)
- Q
ionic product
- QA
quality assurance
- QAPP
quality assurance project plan
- QC
quality control
- Qg
gas flow rate (length2 time−1)
- QM-A
Whatman QM-A, quartz micro-fiber filter
- QSAR
quantitative structure-activity relationships
- R or r
correlation coefficient
- r
chemical production or degradation rate
- R
gas constant
- R
radial position of a particle (centrifugal force calculation)
- r
radius
- R
remote
- R
removed
- R
resistance of the compartment to flux
- R or R
risk
- r
thermodynamic loss term
- ri
mole ratio
- R
universal gas constant (8.315 J K−1 mol−1)
- R-100
oil-resistant respirator protection efficiency against particulate aerosols (99.97%)
- R2 or r2
coefficient of determination
- Rep
dimensionless particle Reynolds number
- RACT
reasonably available control technology
- RAGS
risk assessment guidelines (Superfund)
- RAM
release abatement measure
- RC
reportable concentration
- RCA
replacement cost analysis
- RCA
root cause analysis
- RCRA
Resource Conservation and Recovery Act (U.S.)
- rDNA
ribosomal deoxyribonucleic acid
- Re
Reynolds number (also NR)
- REACH
Registration, Evaluation, Authorisation and Restriction of Chemicals (Europe)
- REL
recommended exposure limit
- REL-TWA
recommended exposure limit (time-weighted average)
- Rep
dimensionless particle Reynolds number
- RFA
RCRA facility assessment (U.S.)
- RfC
reference concentration
- RfD
reference dose
- RFI
RCRA facility investigation (U.S.)
- RH
relative humidity
- RI
remedial investigation
- RI/FS
remedial investigation and feasibility study (U.S. Superfund)
- RIDS
response information data sheet (OSHA)
- RIOPA
Relationship Between Indoor, Outdoor and Personal Air Study (U.S.)
- RMCL
recommended maximum contaminant level
- Rm
intake rate for a medium
- rms
root mean square
- RNA
ribonucleic acid
- RO2
radical made of a chain of organic compounds with O2 substituted for H
- ROD
record of decision
- ROS
reactive oxygen species
- RP
respirable particulates
- RPGen
residential-population generator
- RQ
risk quotient
- RQ
reportable quantity
- RR
relative risk
- RRT
Regional Response Team (Superfund)
- rRNA
ribosomal ribonucleic acid
- Rn
net irradiance
- Rs
intake rate of contaminated soil
- R(t)
reliability function
- RT
residence time
- RT
retention time
- RTECS
Registry of Toxic Effects of Chemical Substances
- RTP
room temperature and pressure
- RΧ
organic compound
- s or sec
second (time)
- S
entropy
- S
severity of risk
- s
solid or sorbed phase (subscript or parenthetic)
- S
solid phase concentration
- S
solubility
- S
sorption
- S
concentration of a limiting substrate (Monod equation)
- S
source or sink
- S/N
signal-to-noise ratio
- S2
variance
- s2
variance of the source
- SA
substrate concentrations in the aqueous phase
- SA
skin surface area
- SAR
structure–activity relationships
- SATB
surface area of the tracheobronchial region
- SCBA
self-contained breathing apparatus
- SCR
selective catalytic reduction
- SD or σ
standard deviation
- SE
standard error
- SEM
scanning electron microscopy
- SES
socioeconomic status
- Sf
filter drag force
- SF
slope factor
- SF6
sulfur hexafluoride
- SG
substrate concentrations in the bulk gas phase
- SGww
gravity of wastewater
- Sh
horizontal surface
- SHEDS
Stochastic Human Exposure and Dose Simulation (model)
- SIC
standard industrial classification
- sin
sine
- SLR
solids loading rate
- SMR
standard morbidity ratio
- SMR
standard mortality ratio
- SNCR
selective noncatalytic reduction
- SOC
synthetic organic chemical
- SOF
soluble organic fraction
- SOM
soil organic matter
- SOP
standard operating procedure
- SOR
surface overflow rate
- SOx
oxides of sulfur
- SO2
sulfur dioxide
- SO2-
sulfate ion
- SPMS
special purpose monitoring station
- SQG
small quantity generator
- SS
steady state (subscript)
- Stk
Stokes number
- STP
standard temperature and pressure
- SVE
soil vapor extraction
- SVOC
semi-volatile organic compound
- SW
surface water
- SW
solid waste
- T
temperature
- t
tonne
- T
total (subscript)
averaging time (exposures)
- t0
initial time
- tD
detention time
- t1/2
half-life
- tan
tangent
- TC
total carbon
- TCDD
tertrachlorodibenzo-para-dioxin
- TCDF
tertrachlorodibenzofuran
- TCE
trichloroethene
- TCLP
toxicity testing leaching procedure
- TCM
tetrachloromercurate
- TCM
transportation control measure
- TDL
tunable diode laser
- TDS
total dissolved solids
- tE
exposure duration
- TEA
terminal electron acceptor
- TEF
toxicity equivalency factor
- TEL
tetraethyl lead
- TEL
threshold effects level (air)
- TEM
transmission electron microscopy
- TEQ
toxicity equivalent
- Tf
time of failure
- Tij
time spent in microenvironment j by person i
- THM
trihalomethane
- TK
toxicokinetic
- TL
typical lifetime
- TLV
threshold limit value
- TLV-C
threshold limit value (ceiling)
- TLV-STEL
threshold limit value-short-term exposure limit
- TMDL
total maximum daily load
- TNT
trinitrotoluene
- TOC
total organic carbon
- TOMS
total ozone mapping spectrometer
- TOV
total organic vapors
- TPTH
triphenyl tin hydroxide
- tpy
tons per year
- T-R
transformer-rectifier
- TRS
total reduced sulfur
- TS
total sulfur
- TSCA
Toxic Substances Control Act (U.S.)
- TSDF
treatment, storage and disposal facility
- TSP
total suspended particulates
- TSS
total suspended solids
- TWA
T wave alternans
- TWA
time-weighted average
- u
velocity
- u
wind speed
- U
epistemic uncertainty
- U
internal energy
- U
potential energy
- U
unknown
- ua
pore air pressure
- uw
pore water pressure
- urms
root-mean-square (rms) speed (gas molecules)
- UAM
urban airshed model
- UASB
upflow anaerobic sludge blanket
- UCC
ultra-clean coal
- UCL
upper concentration limit
- UCL
upper confidence limit
- UDL
upper detection limit
- UEL
upper explosive limit
- UFinter
interspecies uncertainty factor
- UFintra
intraspecies uncertainty factor
- UFother
RfC or RfC uncertainty other than UFinter or UFintra
- UFP
ultrafine particles
- UNEP
United Nations Environmental Programme
- UNFCCC
United Nations Framework Convention on Climate Change
- UR
unit risk value
- USDA
U.S. Department of Agriculture
- UST
underground storage tank
- UTM
Universal Transverse Mercator
- UTS
universal treatment standards
- UV
ultraviolet
- UV-DOAS
differential optical absorption spectroscopy in UV range
- V
fluid velocity
- V
voltage
- V
shear force
- V
speed
- V
stochastic or aleatory uncertainty
- v
vapor phase (subscript or parenthetic)
- V
volume
average linear velocity (length time−1)
average speed (length time−1)
- Vaw
airway volume (length3)
- VC
vinyl chloride (C2H3Cl)
- Vd
volume of distribution
- Ve
minute volume (volume time−1)
- vf
velocity through the filter (length time−1)
- VFA
volatile fatty acid
- Vff
filter fiber volume
- vg
gas velocity
- vg
geostrophic velocity
- VI
vapor intrusion
- VI
volume ingested
- vis
visible light range
- Vmax
maximum reaction rate
- VMT
vehicle miles traveled
- VOC
volatile organic compound
- vp
particle velocity
- Vp
particle volume
- VPD
vapor pressure deficit
- VPH
volatile petroleum hydrocarbons
- VR
volume respired
- VS
volatile solids
- Vtotal
total filter volume
- w
work
- W
body weight
- W
water (subscript)
- W
watt (unit of power; J s−1)
- wB
body weight (mass)
- WET
whole effluent toxicity test
- WHO
World Health Organization
- WLA
waste load allocation
- WOE
weight of evidence
- WOR
weir overflow rate
- WoSE
weight of scientific evidence
- WUE
water use efficiency
- WW
wastewater
- WWTP
wastewater treatment plant
- x
at distance x from x = 0 (subscript)
- x
distance (horizontal)
- XAD
sorbing material; ion exchange resin
- XF
exposure factor (LCA)
- XRD
x-ray diffraction spectrometry
- XRF
x-ray fluorescence
- y
cross-sectional distance, i.e., at distance y from y = 0 (subscript)
- y
width
- Y
modeling result/outcome
- y
year
sample mean
- yp
difference in velocity between the particle and the collection object (length time−1)
- z
at distance z from z = 0 (subscript)
- Z
atomic number
- z
height
- Z
fugacity capacity
- Z
zenith angle (deg)
- Z
electrical impedance (ohm Ω)
- α
packing density (solidity)
- α
alpha particle
- β
beta particle
- γ
gamma ray
- γ
specific weight
- γ
psychrometric constant
- ∑F
sum of forces
- Δ
change
- Δ
displacement
- Δ
heat in a chemical reaction
- ΔG*
standard change in Gibbs free energy
- ΔPdust-cake
pressure drop across dust cake on a filter
- ΔPmedia
pressure drop across filter media
- ΔPtotal
total pressure drop
- ε0
permittivity of free space (8.85 × 10−12 farads m−1)
- µ
specific growth rate of microbe
- µ
dynamic viscosity
- µmax
maximum specific growth of microbe
- η
hour angle (degrees)
- θ
volumetric water content of soil
- θ0
initial soil water content
- λ
average or expected counts or events per unit time (Poisson equation)
- λ
degradation term in chemical decay
- λ
wavelength
- νp
relative velocity between the particle and the target object
- ντ
tangential velocity of gas
- π
3.14159…
- ρ
density (volume length−3)
- ρ0
standard density (1 g m−3)
- ρb
dry bulk density
- ρg
gas density (mass length−3)
- ρp
particle density
- ρw
fluid density (water)
- ρww
fluid density (wastewater)
- σ
Stefan–Boltzmann constant
- τ
tortuosity
- τ
mean residence time at steady state
- τs
shear stress (mass length−1 time−2)
- υ or υv
kinematic viscosity (length2 time−1) = dynamic viscosity divided by density (µ ρ−1)
- υ
specific volume (reciprocal of density; length3 mass−1)
- ϕp
pressure potential
- ϕm
matric potential
- ϕzI
gravitational potential
- ϕo
osmotic potential
- ϕob
overburden potential
- φo
osmotic pressure
- φ
angle (degrees or radians)
- φ
filter porosity
- φ
fugacity coefficient
- φ
latitude (degrees)
- φ°
fraction, ratio, or coefficient
- Χ
leaving group from an organic compound
- Χp
particle diffusivity (length2 time−1)
- ψ
surface deposition
- ΨD
diffusional collection parameter (dimensionless)
- Ψp
particle diffusivity
- Ω
migration velocity (electrostatics)
- Ω
angular speed of the Earth's rotation
- Ω
electrical resistance
- ω
solar azimuth (degrees)
- ω
spherical particle mass