Tema 2.4-7 Flashcards
What are minor constituents in artificial water and their roles?
< 1 mg/kg
Silica likely plays a role in aquatic ecosystems.
Iron: Hemoglobins (vertebrates, some annelids, mollusks), Hematyrin (sipunculids, priapulids), Chlorocruorin (annellids).
Copper: Hemocyanin (mollusks, crustaceans).
Iodine: Thyroxine hormone in vertebrates.
Vanadium & Niobium: Blood pigments in ascidians.
What are the usable forms of nitrogen in the ocean?
Nitrate (NO₃⁻) - Dominant.
Nitrite (NO₂⁻)
Ammonium (NH₄⁺)
Organic Compounds: Nitrogen in organic compounds.
Recycling vs Fixation: Recycling - reusing nitrogen compounds (e.g., decomposition). Fixation - converting atmospheric nitrogen to usable forms.
How does the concentration of nitrogen and phosphorus vary with depth?
Surface: High concentration, absorbed by phytoplankton.
At the bottom: Nitrogen and phosphorus increase due to bacterial decomposition.
What role does silica play in ocean ecosystems?
Silica: Formed as silicate ions or colloidal silica.
Found in diatoms that form frustules; accumulated in diatomaceous mud.
Typically ≤1-5 mg Si/l in the deep ocean.
How do iron and manganese concentrations change in ocean waters?
Iron: Ferric hydroxide is insoluble → low dissolved iron <2 µg Fe/l.
Manganese: Particulate (micelles), concentration 0.3-10 µg Mn/l.
Regional Differences: Higher near estuaries and in neritic zones.
What is dissolved organic matter (DOM) and its sources?
Sources: Decomposition, runoff, exudates from organisms, microbial activity.
Components: Hydrocarbons, carbohydrates, urea, amino acids, pigments, lipids, vitamins.
Importance: Fuel for microbial loops and organic food cycles.
What factors influence light penetration in the ocean?
Infrared (λ > 780 nm): Limited penetration.
Ultraviolet (λ < 380 nm): Limited penetration.
Visible Light (400-700 nm): Most significant penetration.
Photosynthetically Active Radiation (PAR): 400-700 nm, maximum intensity ~2000 µEm⁻²s⁻¹.
What is the extinction coefficient (k) for light in the ocean?
Blue light (λ ~450 nm): k ~0.035 m⁻¹.
Red light (λ ~650 nm): k ~0.140 m⁻¹.
Exponential Decrease: Light intensity decreases with depth.
What are the ecological zones in the ocean based on light penetration?
Euphotic Zone: Sufficient light for photosynthesis.
Dysphotic Zone: Insufficient light for photosynthesis.
Aphotic Zone: No light penetration.
How do water molecules and dissolved organic matter affect light absorption?
Water Molecules: Absorb red spectrum light.
Colored Dissolved Organic Matter (CDOM): Absorbs light, making coastal waters appear yellow-brown.
Chlorophyll: Absorbs visible light.
Suspended Particles: Scatter shorter wavelengths (blue light).
What factors drive ocean currents and pressure gradients?
Wind Patterns: Drive surface currents.
Pressure Gradients: Created by height differences in water.
Coriolis Effect: Deflects water movement based on Earth’s rotation.
What are surface and subsurface currents?
Surface Currents: Driven by wind drag, pressure gradients, and the Coriolis Effect.
Subsurface Currents: Driven by density gradients (temperature and salinity).
How does the Coriolis Effect influence ocean currents?
Deflects moving fluids (water) due to Earth’s rotation.
Northern Hemisphere: Currents move clockwise.
Southern Hemisphere: Currents move counterclockwise.
What is Ekman Transport?
Mechanism: Wind fields create surface currents, forming an Ekman Spiral.
Depth: Affects up to 200 m.
Speed: ~4% of surface wind speed.
Direction: Opposite at deeper layers.
What is Langmuir Circulation?
Requires persistent winds >3.5 m/s.
Forms parallel streaks (windrows) on the ocean surface.
Asymmetry in water movement, intensified near western boundaries.
How do geostrophic currents form?
Created by a balance between pressure gradients and the Coriolis effect.
Northern Hemisphere: Clockwise rotation.
Western Boundary Intensification: Intense flow along western boundaries.
What are warm-core and cold-core rings?
Warm-Core Rings: Form from warm water.
Cold-Core Rings: Form from cold water.
Size: 100-300 km in diameter.
Rotation speed: ≤1 m/s.
Drift: ~10 km/day, typically southwest.
What drives thermohaline circulation?
Density differences caused by temperature (T) and salinity (S).
Global Impact: Represents ~90% of global water movement.
What is the role of thermohaline circulation in Earth’s climate?
Plays a crucial role in climate regulation by distributing heat and nutrients.
Timescale: Takes ~4000 years for a full cycle.
What is Arctic Intermediate Water (AIW)?
Forms in the Arctic and contributes to intermediate water layers driving ocean circulation.
What is the thermohaline circulation’s global fingerprint?
Specific temperature value (~17.5°C) is a key marker for circulation patterns.
