Sources traits and sampling of marine sediments

atmosphere Rivers Surface water Particulate Water column dissolved Solids Solutes, gas, dust, aerosols Surface water biogenic production Water column Particulate dissolved Interface Past interfaces Past interfaces

Residence time of water in the ocean ≈ 3200 years

Ocean crusts reach ages of 200 million years

Seafloor sediments store the memories of the ocean Sediments have physical, chemical and biological characteristics that reflect their origins (where they come from), environment and journey

Categories of solids in the sediment Biogenic (substance produced by life processes) Lithogenic (comes from non biogenic rocks) Authigenic (minerals that are formed in situ; also called hydrogenic)

Aquatic Sediments Bulk Sediment Solids porewater

Physical properties Bulk density Dry density porosity Grain size wet mass dry mass Water volume Total volume Dry Volume Total volume Grain size mass of size fraction vol of size fraction or dry mass total dry vol total

Sediment stratigraphy, sampling considerations age age age

A 20cm long x-ray of laminated sediments showing light summer layers (resulting from algal blooms) and dark winter layers (resulting from heavy rainfall).

Solutes in the sediment porewater

Porewater extraction

incubation

Solids in the sediment Elements Organic and inorganic compounds Minerals

Biological properties Meiofauna Microfauna Macrofauna

Sorting benthic fauna by size

We sample sediments and examine their characteristics to: learn about past and present interactions between the overlying water and the seafloor Search for usable resources (e.g. minerals and fossil fuels) Research basic scientific questions (e.g. paleo magnetism)

Data that has to be taken with every sample of sediment that we ccollect Sample ID Spatial (x:y) location (Lat; Long) Vertical (z) location (water depth in m) sample range (cm into the sediment) Sampling time (min,h,d,mo,yr)

Basics of sediment sampling A. registration (Lat, Long, Depth, Time)

Sediment (core) description http://www.lakescientist.com/research-summary-lake-sediments-provide-natural-seismometer-earthquakes-plate-boundary-fault/

Grab Activated from a vessel Very reliable Disturbs the stratigraphy Not quantitative Shallow penetration Soft sediments (sensitive to stones and shells)

Box corer Operated from a vessel All depth Very reliable preserves the stratigraphy Quantitative Shallow penetration Soft sediments

Manually sampled Short cores Operated by scuba divers Coastal, max depth 100 m Very reliable Cheep (small vessels) Sampling area is limited preserves the stratigraphy Quantitative Shallow penetration Gentle insert Soft sediments

Manually sampled Short cores; modification for ROV Extended depth Pin point sampling with quality control Very expensive

Multi corer Operated from a vessel Repetitions Sampling area is limited All depths preserves the stratigraphy Quantitative Shallow penetration Gentle insert Soft sediments

Gravity corer Operated from a vessel All depths preserves the stratigraphy Quantitative Impact may compact the sediment Medium penetration Impact insert Soft sediments Not good for porewater measurements

Piston corer (a gravity corer with suction mechanism) Operated from a vessel All depths preserves the stratigraphy Quantitative Improved penetration (up to 25 m) Impact insert Soft to medium sediments

Vibra corer Operated from a vessel Operates to depth of hundreds of meters preserves the stratigraphy Quantitative Medium penetration Vibration insert medium sediments Compacts the sediment Requires a power cable

Pneumatic corer Operated by divers working off a mid size vessel operates to depth of 50m preserves the stratigraphy Quantitative Medium penetration Vibration insert medium sediments Compacts the sediment Requires compressed air source

(pneomatic or hydroulic) Manual drill corer (pneomatic or hydroulic) Operated by divers working off a vessel (limited by diving depth and pneumatic pressure) preserves the stratigraphy Quantitative Penetration into hard substrates e.g. rock and corals http://www.youtube.com/watch?v=DuFS2VJY1Xk

IODP http://www.iodp.org/index.php

Deep sea drill corer Operated from big ocean going, specialized ships operates at full oceanic depths preserves the stratigraphy Quantitative Deep penetration (max depth to date =2111m below the seafloor off Japan) All sediment typs Ridiculously expensive

Calcium Compensation Depth (CCD) 4200-4500 m. calcareous ooze (blue

Calcium Compensation Depth (CCD) 4200-4500 m. calcareous ooze (blue