Inputs to systems

Question 1

What are the roles of rivers for the oceans?

Answer 1

Major source of most chemical elements, regulates ocean chemistry and primary productivity.

Question 2

What are the two types of deposition in atmospheric inputs?

Answer 2

Dry deposition of aerosols (direct fallout of particles to the sea) and wet deposition (rain).

Question 3

Why are atmospheric inputs higher in coastal zones?

Answer 3

As most particles are from land.

Question 4

What are examples of atmospheric inputs?

Answer 4

Dust from wind erosion, sea salt, anthropogenic: power plant emissions, car exhausts, fertiliser volatilisation.

Question 5

What are the sources of nitrogen inputs to coastal seas?

Answer 5

Mainly from combustion sources releasing NO/NO2 to the atmosphere where it forms HNO2/NO3 and agricultural emissions releasing NH3.

Question 6

How is the atmosphere sampled?

Answer 6

A tower holds different instruments at the top such as rain samplers, filter towers, pollutant measures and Saharan-dust iron supply samplers. Only samples when wind blows from the ocean and power supplied from containers at the base.

Question 7

What are two examples of toxic metals found in the ocean, and what are their sources?

Answer 7

Combustion of leaded petrol led to increasing surface water concentrations but now decreasing. Mercury supplied to the ocean by atmospheric deposition as Hg2+ in rain.

Question 8

What are the sources of methane?

Answer 8

Produced by anaerobic microbial processes, source from sediments but may be produced at the pycnocline.

Question 9

What % of radiative forcing does methane contribute?

Answer 9

~15%.

Question 10

What % of total CH and natural CH4 emissions do coastal waters contribute?

Answer 10

~3% of total CH, and 10% of natural CH4 emissions.

Question 11

What are the sources of nitrous oxide?

Answer 11

Byproduct of microbial nitrification and acts as an intermediate in microbial denitrification.

Question 12

What % of radiative forcing does nitrous oxide contribute?

Answer 12

~6%.

Question 13

What is the mean surface concentration of nitrous oxide in shelf seas and estuaries?

Answer 13

~109% in shelf seas - more dynamic and well-mixed, show moderate enrichment

~600% in estuaries - often nutrient-rich and influenced by microbial activity (e.g., nitrification and denitrification), can be strong sources of N₂O

Question 14

What % of total ocean emissions is the nitrous oxide flux from continental shelves and estuaries?

Answer 14

7-60%, but expected to increase threefold by 2050.

Question 15

How does dimethylsulphide influence temperature and climate?

Answer 15

DMS produced by phytoplankton, oxidised in the troposphere, contributes to atmospheric acidity and cloud condensation nuclei.

Question 16

What % of total DMS emissions do estuarine and coastal waters contribute?

Answer 16

~8%.

Question 17

What is submarine groundwater discharge?

Answer 17

The direct flow of groundwater into the ocean, usually occurs as a slow diffuse flow.

Question 18

What are the 3 components of SGD?

Answer 18

Meteoric waters, connate waters, recirculated seawater.

Question 19

What are meteoric waters?

Answer 19

Fresh water with recent atmospheric origin.

Question 20

What are connate waters?

Answer 20

Very salty water, incorporated into rock pores during formation.

Question 21

What are the driving forces of meteoric waters?

Answer 21

Hydraulic gradient.

Question 22

What are the driving forces of recirculated seawater?

Answer 22

Hydraulic gradient, tidal pumping, wave set-up.

Question 23

What are the driving forces of connate waters?

Answer 23

Density and thermal gradient.

Question 24

What are the contributing factors to meteoric waters?

Answer 24

Topography, transmissivity, precipitation, evapotranspiration.

Question 25

What are the contributing factors to recirculated seawater?

Answer 25

Tidal range, period, frequency, wind force and direction.

Question 26

What are the contributing factors to connate waters?

Answer 26

Geology and geothermal heating.

Question 27

What are the 3 techniques to detect and quantify SGD?

Answer 27

Infrared imaging, direct measurements - seepage meters, tracers - natural and artificial (dyes).

Question 28

How and why is 226Ra tracer used for SGD?

Answer 28

Use 226Ra as longest half-life of 1600 years. Concentrations of radium are very low in seawater, so high levels in the coastal ocean indicate large SGD fluxes.

Question 29

Why is radium not as effective for fresh SGD?

Answer 29

Radium is bound to particles in freshwater.

Question 30

What chemical reactions can influence fluxes in the subterranean estuary?

Answer 30

• Oxidation of organic carbon adds CO2 -> results in calcite dissolution • High levels of nutrients due to water-rock interactions (P), and anthropogenic inputs (N, P) • Removal of nitrate by denitrification in low oxygen groundwaters • Removal of dissolved iron at freshwater-saltwater interface, and scavenging of other components (e.g. P).

Question 31

What are the glacial inputs to polar shelf seas?

Answer 31

Inputs of iron are sufficient to fuel a phytoplankton bloom. Meltwaters supply iron in solution and as nanoparticles less than 0.1um, both forms are bioavailable.

Question 32

What mechanisms enhance iron in subglacial environments?

Answer 32

Mechanisms unclear; possibly breakdown of iron oxyhydroxides by microbes under anoxic conditions.

Question 33

What are the benthic sources of particles?

Answer 33

Active recycling of elements at benthic interface, longer timescale release of materials into water column.

Question 34

What % of phosphorus for PP can be supplied from sediments?

Answer 34

10-26%.

Question 35

SGD Quantification Techniques ## Footnote limitations

Answer 35

**Radon (²²²Rn) Tracer Method** How it works: Measures radon (high in groundwater) in coastal water; uses mass balance to estimate SGD. Limitations: Affected by mixing, atmospheric loss. Requires precise decay/evasion calculations. **Salinity Mass Balance** How it works: Uses salinity drop to estimate freshwater SGD input. Limitations: Ignores saline SGD. Sensitive to rainfall/tides.

Question 36

Glider Sensors for Primary Production

Answer 36

Key Sensors: * Fluorometer (Chlorophyll-a) * CTD (stratification) * OBS (particles/blooms) * DO sensor (productivity) * PAR (light availability) **Seasonal Trends:** **Spring:** High chlorophyll (bloom). **Summer:** Stratified, may decline. **Autumn:** Possible secondary bloom. **Winter:** Low productivity. ## Footnote Fancy creatures observe dark photos

Question 37

What are the common Buoy Sensors ## Footnote (7)

Answer 37

Likely Sensors: * Fluorometer * Temperature * Salinity (CTD) * DO, * Turbidity, * pH * Nutrients (e.g., nitrate)