Glossary of Monitoring Terms
Compiled by Heather Peterson, US Geological Survey
ADCP: Acoustic Doppler Current Profilers
BMI: Benthic Macro-Invertebrate
Chl a: Chlorophyll a is a green photosynthetic pigment found in most plants, algae, and cyanobacteria. For this project, chlorophyll a concentration is used as a proxy measurement for phytoplankton concentration.
Conductivity: (also known as electrical conductivity, or EC) Conductivity is a measure of a material's ability to conduct an electric current. For this program EC is measured in ambient water. In general, as water's salinity increases, so does the concentration if ions and the water's ability to conduct electric current. EC is generally reported in microSiemens per centimeter (µS/cm).
CTD: An instrument that simultaneously measures electrical conductivity, temperature, and pressure (depth). Often sensors for other constituents such as dissolved oxygen, and pH are also bundled with the CTD sensor array.
Data sonde: an instrument package with sensors that measure conductivity, temperature, pressure (depth), and other water quality constituents such as dissolved oxygen, turbidity, and chlorophyll a. Instrument packages often come with internal data-logging devices. Sondes can be carried by field staff to collect in-situ measurements or left in-situ for extended periods (weeks or months) to collect data at regular (generally 15-minute) intervals.
Discrete Data: Data are collected manually, by monitoring staff during sampling events. Typically sampling events occur weekly, monthly or annually.
DO: Dissolved Oxygen, the amount of gaseous oxygen (O2) dissolved in an aqueous solution. DO is generally reported in mg/l.
DOC: Dissolved organic carbon; the organic carbon present in surface water that passes a 0.2 mm filter.
EC: See Conductivity.
Grab Samples: For this program grab samples are water or sediment samples collected at the sampling site for later analysis in a laboratory, in contrast to data collected in the field with instrumentation such as a data sonde.
OBS: Optical Backscatter, a measure of turbidity or water clarity
OP Pesticides: organophosphate, organophosphorus pesticides
PAHs: Polycyclic aromatic hydrocarbons
PBDE: polybrominated diphenyl ether
PCBs: polychlorinated biphenyls
pH: pH is a measure of the acidity of a solution in terms of activity of hydrogen ions (H+). Materials with a pH below 7 are considered to be acidic, while materials with a pH above 7 are considered to be basic.
ppt: Parts per thousand
psu: practical salinity units measure the conductivity ratio of a sea water sample to a standard KCl solution.
SFB: San Francisco Bay
SiO2: Silica – Silicon Dioxide
Sonde: See data sonde
SSC: Suspended sediment concentration
TEMP: Temperature, generally reported in degrees Celsius
TSS: Total suspended solids; for this program a measurement of the dry-weight of particles trapped by a filter, typically of a specified pore size
Turb: Turbidity, a measure of water cloudiness