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By
Daniel A. Vallero, Ph.D.
Daniel A. Vallero, Ph.D.
Duke University
, Pratt School of Engineering, Department of Civil & Environmental Engineering, Durham, North Carolina,
USA
, 27708
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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.

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)

humidity ratio

Δ

energy (heat) required for reaction

dydx

ordinary derivative of x with respect to y

SA*

substrate concentration at the gas/aqueous interface

Υ¯¯

source mean

τ

mean residence time

xy

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) = πdp24

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)

C¯

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)

D_

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 = 32.2lbmftlbfsec2=980cmsec2

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

ΔGf*0

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)

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

K1aG/A

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)

NRp

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

PDF

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

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)

t¯

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

v¯

average linear velocity (length time−1)

V¯

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

y¯

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

migration velocity (electrostatics)

angular speed of the Earth's rotation

electrical resistance

ω

solar azimuth (degrees)

ω

spherical particle mass

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