Rosette water sampler
The Rosette sampler is the primary sampling instrument for the collection of all Nutrient parameters,
phytoplankton, chlorophyll a, phaeophytin a, and dissolved oxygen from the Biological Category, and
temperature, total suspended solids, turbidity, specific conductance, and pH from the Physical Category.
Water sampling devices range from a bucket dropped over the side of a small boat to large water bottles
sent toward the deep ocean seafloor on a wire. Probably the most commonly used water sampler is
known as a rosette. It is a framework with 12 to 36 sampling bottles (typically ranging from 1.2- to 30liter capacity) clustered around a central cylinder, where a CTD or other sensor package can be attached.
A 12-bottle Rosette sampler system (Sea-Bird Electronics 32 Carousel Water Sampler) will be used to
collect water samples. This equipment allows an operator to remotely actuate a sequence of up to 12
water sampling bottles. This system consists of a CTD (conductivity, temperature and depth sensor Sea-Bird Electronics Model 9 Underwater Unit) attached at the bottom of the Rosette, an A-frame, 1000
feet of multi-conductor cable, a variable speed winch and Sea-Bird Electronics Model 11 Deck Unit with
attached computer. The CTD measures water depth and temperature, which is graphically (CRT)
displayed onboard the research vessel. The bottles can be closed in any predetermined order, remotely
from the deck of the vessel while the array is submerged at the various sampling depths. The Rosette
sampler is equipped with 8 L Niskin bottles.
The depth at which samples will be collected is detected by a pressure transducer on the CTD. To assure
that the display parameters are set to include the entire water column, the Rosette winch operator
obtains a depth sounding from the bridge and writes this on the Rosette form, then adjusts the
computer program parameters controlling the depth range to be displayed (See “Instructions for use of
the Sea-Bird 9/11+...”). The Rosette sampler will then be lowered to the bottom at between .5 and 1
meter/second, raised at least 5 meters after contacting the bottom. The operator will wait three
minutes to allow the sampler to drift away from the disturbed area before the B-2 (2 meters up from the
bottom) sample is taken. The Rosette sampler will be lowered to B-2 and the sample taken.
Additional time intervals of three minutes are allowed to elapse prior to taking the thermocline sample
and the lower epilimnion sample. These intervals provide time for water equilibration within the
Niskins.
The knees of the EBT temperature depth trace will be determined by trisecting the angle between the
epilimnion and mesolimnion temperature traces (upper knee) and the angle between the mesolimnion
and hypolimnion temperature traces (lower knee). The upper knee is the upper a angle intercept, the
lower knee is the lower a angle intercept. The lower epilimnion sample is one meter above the upper
knee. The upper hypolimnion sample is one meter below the lower knee.
Nansen bottles
A Nansen bottle is a device for obtaining samples of seawater at a specific depth.
The bottle, more precisely a metal or plastic cylinder, is lowered on a cable into the ocean, and when it
has reached the required depth, a brass weight called a "messenger" is dropped down the cable. When
the weight reaches the bottle, the impact tips the bottle upside down and trips a spring-loaded valve at
the end, trapping the water sample inside. The bottle and sample are then retrieved by hauling in the
cable.
A second messenger can be arranged to be released by the inverting mechanism, and slide down the
cable until it reaches another Nansen bottle. By fixing a sequence of bottles and messengers at intervals
along the cable, a series of samples at increasing depth can be taken.
The sea temperature at the water sampling depth is recorded by means of a reversing
thermometer fixed to the Nansen bottle. This is a mercury thermometer with a constriction in its
capillary tube which, when the thermometer is inverted, causes the thread to break and trap the
mercury, fixing the temperature reading. Since water pressure at depth will compress the thermometer
walls and affect the indicated temperature, the thermometer is protected by a rigid enclosure. A nonprotected thermometer is paired with the protected one, and comparison of the two temperature
readings allows both temperature and pressure at the sampling point to be determined.
Ruttner sampler
Ruttner water Sampler can be used for limnological and hydro- biological investigation.
It is employed in the water column at various depths in order to obtain water for the analysis of
nutrients and pollutants. Plankton is sampled with a tube in order to allow for sampling over the entire
water depth and in different areas.
Gab Sampler
This sampler is designed to collect an accurate representative sample of the sediment bottom. The bite
of the sampler should be deep enough so all depths are sampled equally. The closing mechanism is
required to completely close and hold the sample as well as prevent wash-out during retrieval. Likewise,
during descent the sampler should be designed to minimize disturbance of the topmost sediment by the
pressure wave as it is lowered to the bottom.
The proven design of the super heavyweight grab sampler facilitates its use in all types of bottom
substrates, except hard-packed clays. A simple pin mechanism prevents accidental closure of the dredge
while in transit.
Plankton Net
Plankton Nets are a modification on the standard trawl used to collect planktonicorganisms, of nearly
any size, intact. Towed by a research vessel, Plankton Nets have a long funnel shape that allows them to
catch differently sized plankton simply by changing the mesh size of the net. At the end of the funnel is a
collection cylinder called a cod-end. Phytoplankton can be collected with a Ruttner sampler.
Primary productivity, Nutrients and Pollution
Primary productivity is a term used to describe the rate at which plants and other photosynthetic
organisms produce organic compounds in an ecosystem. There are two aspects of primary productivity:
Eutrophication is the “excess supply of nutrients leading to increased biological productivity”
The nutrients found in seawater are essential to the survival of plant and marine life. Phosphate,
Nitrate- Nitrogen, Nitrite- Nitrogen and Ammonical- Nitrogen are the main nutrients measured for
analysis of sea water.
Pollution in the ocean directly affects ocean organisms and indirectly affects human health and
resources. Oil spills, toxic wastes, and dumping of other harmful materials are all major sources of
pollution in the ocean.
Samples of seawater for determining the above factors can be obtained with Ruttner sampler, Nansen
bottles and rosette sampler. Bottom grab sampler can be used for collecting of sediments.