Conversion Factors, Datums, and Abbreviations and Acronyms


Conversion Factors


Multiply	By	To obtain
Length
foot (ft)	0.3048	meter (m)
mile (mi)	1.609	kilometer (km)
Volume
liter (L)	0.2642	gallon (gal)
Mass
gram (g)	0.03527	ounce, avoirdupois (oz)
kilogram (kg)	2.205	pound avoirdupois (lb)
Flow rate
gallon per minute (gal/min)	0.06309	liter per second (L/s)
Pressure
atmosphere, standard (atm)	101.3	kilopascal (kPa)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:


°F=(1.8×°C)+32


Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (µS/cm at 25°C).


Concentrations of most chemical constituents in water are given either in milligrams per liter (mg/L) or micrograms per liter (µg/L).


Chlorofluorocarbon (CFC) concentrations are given in units of picograms per kilogram (pg/kg) and picomoles per kilogram (pmol/kg). One picogram is 10^-12 grams. One picomole is 10 ^-12 moles. One mole contains 6.022 × 10²³ atoms or molecules of a substance. Sulfur hexafluoride (SF₆) concentrations are given in units of femtograms per kilogram (fg/kg) and femtomoles per kilogram (fmol/kg). One femtogram is 10^-15 grams. One femtomole is 10^-15 moles. CFC and SF₆ concentrations in gases are expressed as a mixing ratio, that is, volume of gas per volume of dry air, in parts per trillion [parts per trillion by volume (pptv)]. The mixing ratio is calculated as the atmospheric concentration that would yield the measured aqueous concentration assuming equilibrium partitioning between atmosphere and water under the specified conditions (recharge temperature, recharge altitude, and excess-air concentration). 


Tritium concentrations are given in units of Tritium Units (TU). Based upon a tritium half-life of 12.32 years (Lucas and Unterweger, 2000), 1 TU is equal to 3.22 picocuries per liter.


Helium-3 (³He) data are reported as δ values computed from the formula


where R_x is the ratio of ³He to ⁴He in the sample, R_STD is the ³He to ⁴He ratio of the reference standard air (1.384 × 10^-6), and δ³He is expressed in parts per hundred.


Excess-air concentrations (see Glossary), helium (He) concentrations, and neon (Ne) concentrations are reported in units of cubic centimeters (at standard temperature and pressure) per kilogram of water (cc(STP)/kg). One cc(STP) of He or Ne is equal to 2.6868×10¹⁹ atoms. 


Datum


Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).


Altitude, as used in this report, refers to distance above the vertical datum.


Abbreviations and Acronyms


Abbreviation or Acronym	Definition
Ar	argon
14C	carbon-14
CFC	chlorofluorocarbon
CH4	methane
CO2	carbon dioxide
DWH	NAWQA Data Warehouse
Fe	iron
FSS	Flow System Study
FY	fiscal year
He	helium
3H	tritium
3He	helium-3
4He	helium-4
LUS	Land-Use Study
MAAT	mean annual air temperature
MAS	Major-Aquifer Study
Mn	manganese
N2	nitrogen (in the form dinitrogen)
NAWQA	National Water-Quality Assessment Program
Ne	neon
O2	oxygen (in the form dioxygen)
REF	Reference well
SF6	sulfur hexafluoride
SIO	Scripps Institution of Oceanography
STP	standard temperature and pressure
SUS	Study-Unit Survey
TU	tritium unit
UA	unfractionated air
USGS	U.S. Geological Survey

First posted January 27, 2011