4.1 Water Systems (DP IB Environmental Systems & Societies (ESS): HL): Flashcards

The movement of water from one store to another without a change of state is called a transfer.

Evapotranspiration is the combined process of evaporation and transpiration, where water moves from the Earth's surface and plants into the atmosphere.

An aquifer is a layer of permeable rock or sediment that holds and transmits groundwater.

A steady state is when the inputs and outputs of a water body are balanced so that its water level remains constant over time.

A steady state is achieved when the total water input equals the total water output.

The main inputs to a water body include precipitation, surface run-off, and groundwater inflow.

Water leaves a lake through river outflow, evaporation, and groundwater outflow.

Sustainable water harvesting is taking water from a water body at a rate that does not exceed the rate of natural replenishment, ensuring the steady state is not disrupted.

True.

If outputs exceed inputs, water is lost more quickly than it is replenished, causing the water body to shrink.

Irrigation increases evapotranspiration rates and alters water distribution, sometimes causing higher atmospheric moisture and local rainfall.

Excessive irrigation can lead to increased surface run-off and contribute to water pollution.

After deforestation, surface run-off increases significantly, as there is less vegetation to absorb rainfall and slow its movement.

Urbanisation is the process of transforming natural landscapes into urban areas with buildings, roads and infrastructure, often replacing permeable surfaces with impermeable ones.

Urban surfaces made of concrete and asphalt are impermeable, which prevents infiltration and increase run-off.

False.

Deforestation decreases infiltration and groundwater recharge because there is less vegetation to absorb and slow rainfall.

Urbanisation increases flooding because impermeable surfaces prevent infiltration, causing more rainfall to become surface run-off, which can overload drainage systems.

Evapotranspiration is the combined process of water evaporating from land and water surfaces and transpiration from plants into the atmosphere.

By comparing total inputs and outputs, we can ensure extraction does not exceed natural replenishment, thus preventing depletion of aquifers.

Polarity in water refers to the uneven distribution of charge across the molecule, with a slight positive charge near the hydrogens and a slight negative charge near the oxygen.

A hydrogen bond is a weak attraction between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another.

Water molecules are polar, meaning they have an uneven distribution of charge.

Cohesion between water molecules is caused by hydrogen bonding which makes the molecules stick together and allows water to form droplets and maintain surface tension.

Adhesion is the tendency of water molecules to stick to other materials, which helps water move through narrow spaces like plant xylem during capillary action.

The ability of water to dissolve many substances is due to its polarity.

Water is called a universal solvent because its polarity allows it to dissolve a wide range of substances, enabling the transport of nutrients and gases in living organisms.

High specific heat capacity means that water can absorb or lose a large amount of heat with little change in temperature, helping to regulate temperatures in organisms and environments.

Water is most dense at 4 °C, causing ice to float on water.

The lower density of ice causes it to float on water, forming an insulating layer that prevents the water below from freezing completely, thus protecting aquatic life.

True.

Water’s transparency allows light to penetrate, enabling photosynthesis in aquatic plants and algae.

Cold water holds more dissolved oxygen than warm water, supporting more aquatic life.

A carbon sink is a natural system, like the ocean, that absorbs and stores carbon dioxide (CO₂) from the atmosphere, helping to slow the increase of atmospheric CO₂.

The oceans absorb large amounts of carbon dioxide (CO₂) from the atmosphere, which helps to slow the increase of CO₂ and moderate the pace of climate change.

When CO₂ is absorbed by the ocean, it reacts with seawater to form carbonic acid, which lowers the pH of the water and causes ocean acidification.

Marine organisms with calcium carbonate shells or skeletons, such as corals, molluscs, and some plankton, are most affected by ocean acidification.

False.

Short-term carbon sequestration in the ocean mainly occurs as dissolved CO₂ in seawater, not in seabed sediments.

Ocean acidification is the process by which CO₂ absorbed by the ocean reacts with seawater to form carbonic acid, lowering the pH of the water and negatively impacting marine life.

Over the long term, carbon is sequestered in the ocean when marine organisms absorb CO₂ to build their shells or tissues.

If the oceans reach a saturation point and can no longer absorb CO₂ efficiently, atmospheric CO₂ could rise more quickly, accelerating climate change.

Carbon sequestration is the process by which carbon dioxide (CO₂) is absorbed from the atmosphere and stored in oceans, marine organisms, or sediments.

True.

Ocean acidification occurs when CO₂ dissolves in seawater, forming carbonic acid, which lowers the pH and harms marine life.

Over the long term, carbon is sequestered in ocean sediments as organic and inorganic carbon, helping regulate the global carbon cycle.

Water stratification refers to the layering of water in a body of water due to differences in temperature and density.

Warmer water is less dense and stays on the surface, while colder, denser water sinks to the bottom.

Stratification restricts the mixing of water between different layers in a lake or ocean.

A thermocline is a transition layer between the warmer, mixed water at the surface and the cooler, denser water below, where temperature drops rapidly with depth.

Water near the surface is usually warmer due to sunlight, while deeper water is cooler.

Water is most dense at 4°C.

False.

Lakes show greater stratification during summer and winter, with mixing usually occurring in spring and autumn.

Hypoxic water contains very low levels of dissolved oxygen, which can harm aquatic organisms.

Stratification leads to the surface layer being oxygen-rich and the deep layer being nutrient-rich but often oxygen-poor due to lack of mixing.

In a stratified lake, the deep water often contains higher concentrations of nutrients.

Global warming intensifies ocean stratification by making surface waters warmer and less dense, which increases separation between layers and reduces mixing.

Salinity affects water stratification because higher salinity increases water density.

Because water is most dense at 4°C, colder water and ice are less dense and stay at the surface, allowing lakes to freeze from the top down.

Upwelling is the process in which cold, nutrient-rich water rises from deep below to the surface of oceans or freshwater bodies.

Upwellings are important because they bring nutrients like nitrates and phosphates to the surface, supporting phytoplankton growth and forming the base of marine food webs.

False.

Wind-driven upwellings usually occur along the west coasts of continents, such as California, Peru, and Namibia.

Upwellings bring nutrients from deep waters to the surface, supporting phytoplankton growth.

Overfishing in upwelling regions can deplete fish populations and potentially cause the collapse of ecosystems if not managed sustainably.

The Peru upwelling system in South America supports major fisheries for anchovies.

Thermohaline circulation is the global ocean current system driven by differences in temperature and salinity that regulate water density.

Cold, salty water is denser than warm, fresh water, so it sinks in the North Atlantic, starting the conveyor belt.

The thermohaline circulation system is also known as the ocean conveyor belt.

True.

Thermohaline circulation helps to regulate the climate by transferring heat from the tropics to the poles.

The Gulf Stream is part of the thermohaline system and brings warm water from the Gulf of Mexico to Western Europe.

Climate change can cause melting ice caps to add freshwater to the oceans, reducing salinity and density, which could slow or stop the conveyor belt and lead to significant climate shifts.

An upwelling is an area in oceans or freshwater bodies where cold, nutrient-rich water rises to the surface, supporting phytoplankton growth and productive ecosystems.

The thermohaline circulation is driven by differences in temperature and salinity of seawater, which affect water density.

Climate change can alter wind patterns and increase glacial melt, which may disrupt upwelling cycles by changing nutrient availability and weaken the thermohaline circulation by reducing seawater salinity and density, potentially affecting global climates and marine food webs.