Cevat Sediments and Sampling Methods

Flashcards about sediment sampling, categorizing grain size, and seabed integrity.

Grab Sampling

Sampling method that provides an often disturbed surface sample, excellent for grain size analysis.

Coring

Sampling method that uses a gravity core, piston core, box core, or vibrant core to provide an undisturbed view of sediment grain size variation with depth.

Drilling Rig

Sampling method that involves jacking up a vessel to drill deep into sediment and bedrock, requiring a purposely fit vessel.

Grab Samplers

GRAP sampler triggered by hitting the seabed, capturing sediment in its closing movement, examples include Smith MacIntire, Van Veen, and Shipek grab.

Shipek Grab

A type of GRAP sampler that doesn't close jaws but scoops up sediment, reducing the chance of jamming.

Advantages of GRAP Sampling

Easy to deploy and quick; good recovery even from small vessels in rough seas; provides a good size sample for green size analysis.

Disadvantages of GRAP Sampling

Chances of fine green sediments washing out; possible blockage of the jaws; sample can get mixed and little seabed structure is preserved.

Gravity Core

Coring technique ideal for muddy sediments.

Gravity Core Structure

Steel barrel with a plastic liner and a core catcher at the bottom to prevent sediment from coming back out.

Vibra Core

Coring technique that involves vibrating into the seabed.

Piston Core

Works well in finer sediments and utilizes a piston that triggers a release into freefall from a certain height above the bed.

Box Core

Specialist core that uses a shoveling technique to collect sediments in a box, allowing for side window viewing of internal structures.

Multicore

Technique that uses a frame with multiple tubes to collect replicates from the same site for different analyses.

Rotary Core Barrel System (RSPB)

System designed to recover core samples from firm to hard sediments and even igneous basement, requiring a vessel with dynamic positioning.

Advantages of Coring and Drilling

An undisturbed sample, but can have some disturbance with vibration and mechanical movement.

Uses of Deep Cores

Environmental and climate reconstruction by revealing past fauna, sediment distribution, temperature, and chemical markers.

Disadvantages of Coring and Drilling

Costly, requires a big vessel with dynamic positioning, best done in favorable weather, and is more time consuming.

Sample Processing Steps

Subsampling, specifying grain size, and determining how to investigate the greens size.

Green Investigation Options

Sphere of same maximum length, minimum length, same weight, same volume, or same surface area.

Common Grain Size Parameter

All the greens with the sphere passing the same siff aperture.

Phi Scale

Scale to make grain sizes dimensionless and logarithmic.

Phi Definition

Negative value for the logarithm to the base of two of the diameter of your grain to a normalized diameter of one millimeter.

Wentworth scale

A scale from 1922 that calls for the boundary between sand and gravel which is minus one five.

Grain Size and Phi Relationship

The higher the defy number, the smaller the grain size.

Dry Sieving

Technique that is suited for Grain sizes over 50 micron, in fact, over 63 three micron,

Grain Size Analysis Methods

Techniques used for really sediments: laser (Coulters counter and laser sizes), electro microscopes, satyagraha, or sedimentation effects of sediment through the water column.

Dry Sieving Method

Putting sediment in Elvan and getting it through a stack of successively finer ourselves.

Wet Sieving

Forcing sediment through the safe apertures with water.

Pre-Treatment Technique

Washing sediment with fresh water using a Buechner funnel to remove salt before drying.

Optional Treatment Technique

Removing organic debris with hydrogen peroxide.

Preventing Flocculation

Using a stir dispersion agent and a vibrating bath to break them apart.

Ternary Diagram

Diagram of gravel versus sand versus mud where the small means gravelly or sandy.

Clay Importance

Sediments cohesive and changes the dynamics of how it actually all moves.

Half Fi Analysis

summarise your greenside date. you have your PHY sized flosses. You could do it also per quarter fi.

Median Definition

Grain size from which 50 percent of the sun is finer.

Mode Definition

The most common grain size in a population, that is actually the peak of a histogram

Bi Model sediment distribution

Two populations of sediments and both have a histogram related to it

Sorting

Then that's just a way of saying that's a standard deviation for sediments distribution

Skewness

Actually how distorted it is, how asymmetric it is.

Control Seat

It's more how peak peak nice UT is or how flat it is.

Skewness tail

Using a tail along that positive end, that means you have a tail in the really fine particles.

Log Scale

Used to work out at home whether you get to the same, how do you calculate the great size at this curve on a log scale?

Sediment processes

Variations in these processes even through time, look for processes through the paleo environment change.

offshore sediments

Where there is no silts and clays in a way that need to be distinguished, because all of it is called moat.

Red Rose Bay

Protected bay. And so the energy there is a lot less than it would be out in the Irish Sea.

Turbines Cause Stronger Currents

Have cut tidal currents of more than two metres per second increase

Seabed integrity

That is what this does to contribute to this energy transition and to make sure it's sustainable, to make sure that that the seabed will not have to suffer too much

Seabed Integrity

Important to know what those seabed mobility is at the moment but that sediments get swept away, then the habitat that the sediment supports will also be damaged

Employment Opportunities

Looking pretty good because seabed integrity will have to be monitored for the lifespan of these many, many difference seabed infrastructures.