''For information about the conductivity-temperature-depth (CTD) instrument, see:

CTD (instrument) ''For information about the CTD-rosette equipment package as a whole, see: Rosette sampler'' A CTD or sonde is an oceanography instrument used to measure the electrical conductivity, temperature, and pressure of seawater (the D stands for "depth, ...

.''

A rosette sampler (also known as a CTD-rosette or carousel) is a device used for

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...

sampling in deep water. Rosette samplers are used in the

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

and large inland water bodies such as the North American

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

in order to investigate

quality Quality may refer to: Concepts *Quality (business), the ''non-inferiority'' or ''superiority'' of something *Quality (philosophy), an attribute or a property *Quality (physics), in response theory *Energy quality, used in various science discipli ...

. Rosette samplers are a key piece of equipment in

oceanography Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamic ...

and have been used to collect information over many years in repeat

hydrographic surveys Hydrographic survey is the science of measurement and description of features which affect maritime navigation, marine construction, dredging, offshore oil exploration/offshore oil drilling and related activities. Strong emphasis is placed o ...

Description

A rosette sampler is made of an assembly of 12 to 36 sampling bottles.Woods Hole Oceanographic Institution, "Rosette Sampler"
/ref> Each bottle is a

volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...

that range from a minimum value of 1.2 L to a maximum value of 30 L. All of them constitutes the rosette sampler and are clustered around a cylinder situated in the center of the assembly, where there is a sensing system called Sea-Bird or CTD, that stands for "Conductivity, Temperature and Depth", although other variables can be measured by modern CTDs (e.g. water

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can ...

, dissolved

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

concentration In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', an ...

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

concentration and pH).Civil & Environmental Engineering Department at Michigan Tech, "CTD and the Rosette samples on Lake Superior"
/ref> The apparatus is attached to a wire rope. A winch on board of the boat unrolls the rope during descent and rolls up it during the ascent (i.e. at the end of the samples collection). During operations in the ocean, a rosette sampler can approach the seabed at a distance from 1 to 5 m, depending on the particular sea conditions. The opening of each sampling bottle can be automatic (by reaching a certain depth) or manual (by operator, remotely).

Applications

Water sampling is used in general for

chemical analysis Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separati ...

and ecotoxicological assessment.Jan Brant, "Collection of water samples"
/ref> A rosette sampler is preferred to

Winchester sampler Winchester is a cathedral city in Hampshire, England. The city lies at the heart of the wider City of Winchester, a local government district, at the western end of the South Downs National Park, on the River Itchen. It is south-west of Lon ...

for collection of water sampling at depths greater than 50 m.

References

Bibliography

U.S. Environmental Protection Agency, "Field Sampling Using the Rosette Sampler"
Water management Water pollution Oceanography Limnology Oceanographic instrumentation Water and the environment Hydrography {{measurement-stub