Influence of Sediment Characteristics on Heavy Metal Toxicity in an Urban Marsh

Glossary

Analysis of variance (ANOVA)

Statistical method that yields values that can be tested to determine whether a significant relation exists between variables.

Atomic absorption spectrophotometry

An analytical technique used to measure a wide range of elements in materials such as metals, pottery, soils, and glass. A sample solution of material is atomized in a spectrophotometer (for example, in a flame burner or graphite furnace). Light of a suitable wavelength is then applied. The amount of light absorbed by the atoms of the sample is proportional to the concentration of the element in the solution, and hence in the original material.

Benthic

Of or related to organisms (e.g., protozoa, nematodes) living on or in sea or lake bottoms.

Bivariate correlation

The degree to which two variables are related.

Cation

An ion (charged atom) or group of ions having a positive charge.

Chironomid

A member of the freshwater insect family Chironomidae.

Cold-vapor generation

An analytical technique used to measure mercury and other metals that can be easily volatilized. A sample solution of material (such as sediment or detritus) is treated so as to put the mercury in its elemental state. Then air is bubbled through the solution and a mercury vapor is formed. The mercury vapor is collected in a cell through which a suitable light wavelength is passed. The amount of light absorbed by the atoms of mercury is proportional to the concentration of the element in the solution, and hence in the original material.

Control

A parallel experiment used as a standard of comparison to judge the effects of the actual experiment. Controls can be negative or positive. Subjects in a negative control undergo the same treatment as subjects in the actual experiment except for the omission of the procedure or agent (e.g., a heavy metal) that is being tested. Subjects in a positive control are treated with a surrogate of the procedure or agent that's being tested in the actual experiment (e.g., a heavy metal toxicant) in order produce a biological effect and confirm the basic conditions of the actual experiment (e.g., that heavy metals cause reduced growth and mortality in midge larvae).

Detritivore

An animal that feeds on detritus, the organic debris from decomposing organisms and their products.

Instar

A stage in the life of an insect or other arthropod between two successive molts.

Macroinvertebrate

An animal, such as an insect or mollusk, that lacks a backbone or spinal column and can be seen with the naked eye.

mM (millimole)

One one-thousanth of a mole (see below).

M (mole)

The amount of a substance that contains as many atoms, molecules, ions, or other elementary units as the number of atoms in 0.012 kilograms of carbon 12. The number is 6.0225 x 10²³, or Avogadro's number. It is also called a gram molecule.

Negative control

A control (see definition above) in which the procedure or agent that's being tested in the actual experiment (e.g., a heavy metal toxicant) is omitted.

Oligohaline

Describing a body of water with a salinity measure of 0.5 to 2.5 parts per thousand (or 0.5 to 2.5 grams of salt per liter).

Oxic

Describing concentrations of oxygen in water or sediment that are normal.

Pearson coefficient

Statistical measure reflecting the degree of linear relationship (as plotted on a graph) between two variables. Also called the Pearson product moment correlation.

p ≤ 0.05

An indicator of statistical significance in which the probability of achieving the result due to chance alone is less than or equal to 5 in 100.

pH buffer

A substance that minimizes change in the acidity or basicity of a solution when an acid or base is added to the solution.

SEM-AVS

Simultaneous extracted metal (SEM) minus (-) acid volatile sulfide (AVS): a measure of sediment toxicity based on the amount of sulfide in the sediment that can bind with toxic heavy metals and make them unavailable to plants and animals.

Subchronic toxicity

Adverse effects in an organism resulting from repeated dosage or exposure to a substance over a short period, usually about 10% of the organism's lifespan.

Suboxic

Describing concentrations of oxygen in water or sediment that are extremely low and have no perceptible gradients. These amounts of oxygen support limited types of aquatic plants and animals.

T-test

Statistical technique used to analyze the differences in means between two groups.

Trace Metal Standard 1

A solution, approved by the U.S. Environmental Protection Agency, known to contain certain amounts of metals. It is used to verify that metal concentrations are being measured accurately.

Tukey post hoc test

Statistical method that compares two means to determine whether or not they are significantly different.

Volatilize

To make volatile (turn into vapor).