4.1 How Important are Water and Carbon to Life on Earth? Flashcards
How important is water to life on Earth?
Water is key to understanding the evolution of life on Earth as it allows organic molecules to mix and form complex structures.
What is the ‘Goldilocks zone’?
The ‘Goldilocks zone’ is the distance from the Sun where conditions are just right for water to exist in liquid form.
Earth is in this zone explaining the ubiquity of water.
How does water affect thermal conditions on Earth?
Water helps to create benign thermal conditions on Earth. For example, oceans, which occupy 71 per cent of the Earth’s surface, moderate temperatures by absorbing heat, storing it and releasing it slowly. Water also moderates the environment in other ways. Clouds made up of tiny water droplets and ice crystals reflect around a fifth of incoming solar radiation and lower surface temperatures. At the same time water vapour, a potent greenhouse gas, absorbs long-wave radiation from the Earth helping to maintain average global temperatures almost 15 C higher than they would be otherwise
What percentage of living organisms is made up of water?
Water makes up 65-95 percent of all living organisms.
Why do plants need water?
Plants need water for photosynthesis, respiration, transpiration, maintaining rigidity, and transporting nutrients.
What is the role of water in human and animal bodies?
Water is the medium for all chemical reactions, including circulation of oxygen and nutrients.
How is water used economically?
Water is used for generating electricity, irrigation, recreational facilities, and in various industries.
How are the carbon and water cycles closed systems?
On a global scale the water and carbon cycles are closed systems driven by the Sun’s energy (which is external to the Earth). Only energy (and not matter) cross the boundaries of the global water and carbon cycles-hence we refer to these systems as closed
How can the carbon and water cycles open systems?
At smaller scales drainage basins or forest ecosystems, the suns energy crosses system boundaries.
How much water does the ocean hold?
97% of water on the planet- dominates the global water cycle.
Freshwater is only a tiny proportion of all water on the planet and 3/4 is frozen in the ice caps of Greenland and Antarctica.
Water stored below ground in permeable rocks only amounts to 1/5 of fresh water.
Why is there such little water in the atmoshpere?
Due to the rapid flux of water into and out of the atmosphere. The average residence time of a water molecule is only 9 days.
How much water does the global water cycle circulate?
505,000 km3
What is the significance of carbon to life on Earth?
Carbon is essential for life as it forms the basis of large molecules like proteins, carbohydrates, and nucleic acids.
Apart from its biological significance, carbon is used as an economic resource. Fossil fuels such as coal, oil and natural gas power the global economy. Oil is also used as a raw material in the manufacture of products ranging from plastics to paint and synthetic fabrics. Agricultural crops and forest trees also store large amounts of carbon available for human use as food timber paper textiles and many other products.
Where is carbon stored on Earth?
Carbon is stored in carbonate rocks, sea floor sediments, ocean water, the atmosphere, and the biosphere.
What are the two cycles of carbon?
The carbon cycle consists of a slow cycle and a fast cycle.
What is the slow carbon cycle?
The slow carbon cycle involves carbon stored in rocks and fossil fuels, which is locked away for millions of years.
The total amount of carbon circulated by this slow cycle is between ten and 100 million tonnes a year. CO, diffuses from the atmosphere into the oceans where marine organisms, such as clams and corals, make their shells and skeletons by fixing dissolved carbon together with calcium to form calcium carbonate (CaCO3). On death, the remains of these organisms sink to the ocean floor. There they accumulate and over millions of years, heat and pressure convert them to carbon-rich sedimentary rocks
Typical residence times for carbon held in rocks are around 150 million years. Some carbon-rich sedimentary rocks, subducted into the upper mantle at tectonic plate boundaries, are vented to the atmosphere in volcanic eruptions. Others exposed at or near the surface by erosion and tectonic movements are attacked by chemical weathering Chemical weathering processes such as carbonation are the result of precipitation charged with CO, from the atmosphere, which forms a weak acid. The acid attacks carbonate minerals in rocks releasing CO, to the atmosphere, and in dissolved form to streams, rivers and oceans
What is the fast carbon cycle?
The fast carbon cycle involves rapid exchanges of carbon between the atmosphere, oceans, living organisms, and soils.
Land plants and microscopic phytoplankton in the oceans are the key components of the fast cycle.
Through photosynthesis they absorb CO, from the atmosphere and combine it with water to make carbohydrates (sugars/glucose). Photosynthesis fundamental process and the foundation of the food chain. Respiration by plants and animals is the opposite process and results in the release of CO, Decomposition of dead organic material by microbial activity so returns CO2 to the atmosphere.
In the fast cycle, carbon exchange also occurs between the atmosphere and the oceans. Atmospheric CO2 dissolves in ocean surface waters while the oceans ventilate CO2 back to the atmosphere. Through the exchange individual carbon atoms are stored (by natural sequestration) in the oceans for, on average about 350 years.
What is the global water cycle?
The global water cycle consists of three main stores: the atmosphere, oceans, and land.
What are the principal flows in the water cycle?
The principal flows are precipitation, evaporation, transpiration, run-off, infiltration, percolation, and throughflow.
What is the water balance equation and what does it show?
The water balance equation summarises the flows of water in a drainage basins over time. It states that precipitation is equal to evapotranspiration and streamflow plus or minus water entering or leaving storage.
Precipitation (P)= Evapotranspiration (E)+ Streamflow (Q)+/- Storage
What is precipitation?
Precipitation is water and ice that falls from clouds towards the ground, including rain, snow, and hail.
High-intensity precipitation (eg. 10-15 mm/hour) moves rapidly overland into streams and rivers, because it is falling at a rate that exceeds the infiltration capacity of the soil.
What is transpiration?
Transpiration is the diffusion of water vapour to the atmosphere from the leaf pores of plants.
What is condensation?
Condensation is the phase change of vapour to liquid water when air is cooled to its dew point.
What are the different types of clouds?
- Cumuliform clouds, with flat bases and considerable vertical development most often form when air is heated locally through contact with the Earth’s surface. This causes heated air parcels to rise freely through the atmosphere (convection), expand (due to the fall in pressure with altitude) and cool. As cooling reaches the dew point, condensation begins and clouds form
- Stratiform or layer clouds develop where an air mass moves horizontally across a cooler surface (often the ocean). This process, together with mixing and turbulence is known as advection.
- Wispy cirrus clouds, which form at high altitude, consist of tiny ice crystals. Unlike cumuliform and stratiform clouds they do not produce precipitation and therefore have little influence on the water cycle.
