Water and Carbon Cycle
How humans, flora and fauna use water
evolution of life on earth - enables organic molecules to mix and form more complex organic structures
liquid water increases chance of life forms on a planet
water helps create helpful thermal conditions on earth in three main ways:
oceans - moderate temperatures by absorbing heat, storing it and release it slowly
clouds - made up of tiny water droplets and ice crystals reflect around a fifth of incoming solar radiation with lowers surface temperatures
water vapour - water vapour in the atmosphere absorbs long wave radiation from the Earth helping to maintain average global temperatures almost 15 degrees higher than would be otherwise
The size of major stores:
atmosphere - 13,000 cubic kilometres (0.001% of water)
hydrosphere - 1,370,000,000 cubic kilometres (96.5% of water)
cryosphere - 2%
pedosphere - 0.023%
biosphere
lithosphere- 30% of all freshwater, 0.7% of all water
The main inputs and outputs of the water cycle
precipitation - water and ice falls from clouds when vapour cools to dew point and condenses into water droplets.
snowmelt - melting snow can cause water to be moved between stores as glaciers, to stores as rivers/runoff/groundwater
evapotranspiration - movement of water from the earths surface to the atmosphere
The processes of the water cycle
evaporation - evaporation is phase change of liquid water to vapour, main pathway by which water enters atmosphere.
transpiration - diffusion of water vapour out of the stomata
condensation - process of water vapour turning to water, when air cools to due point. clouds form through condensation.
environmental lapse rate - vertical temperature profile for the lower atmosphere at any given time. on average the temperature falls by 6.5 degrees for every km of height gained.
dry adiabatic lapse rate - the DALR is the rate at which a parcel of dry air cools. Cooling, caused by adiabatic expansion, is approximately 10 degrees a km
saturated adiabatic lapse rate - the rate at which a saturated parcel of air, cools as it rises through the atmosphere. because condensation releases latent heat, the SALR, at around 7 degrees a km is lower than the DALR.
cloud formation- clouds form when water vapour is cooled to due point. this occurs when: air warmed by contact with ground or sea rises through the atmosphere, it cools by adiabatic expansion (process known as convection). air moves horizontally across a cooler surface (process known as advection). air masses rise as they cross a mountain barrier, or as turbulence forces their ascent.
precipitation - water and ice that fall from clouds, forms when vapour cools to dew point and condenses into water droplets.
interception - vegetation intercepts precipitation, either flowing down stems or stuff that is not intercepted falls as through fall
infiltration - water moves down through the soil through gravity
percolation - filtering of water through porous materials
overland flow - rainfall always infiltrates soil, only flow occurs when soil is saturated
saturated overland flow - rainfall intensity exceeds infiltration capacity, so overland flow occurs
throughflow - lateral movement of water through soil
groundwater flow - water percolates soil, it is then able to flow through the ground, through joints and rock pores
ablation - ablation is the loss of ice through melting, evaporation, sublimation and calving
How carbon is important to the natural world and humans
used for fuels
all living things are made from carbon
food made from carbon
carbon gas regulates climate
biological activity contantly converts carbon
human activities onvert coal, natural gas etc. into carbon dioxide.
The size of major stores in the carbon cycle
atmosphere - 0.0017% of all carbon
hydrosphere - 0.038% of all carbon
cryosphere - 0.004% of all carbon
pedosphere - 0.0031% of all carbon
biosphere - 0.0012% of all carbon
lithosphere - 99.9% of all carbon
The processes of the carbon cycle
precipitation
photosynthesis - flux of carbon from atmosphere to land plants and phytoplankton via photosynthesis is around 120 gigatonnes a year.
respiration - process in which carbohydrates are converted to co2 and water. reverse of photosynthesis, relases co2. one thousand times greater than the carbon moving through the slow carbon cycle.
decomposition - bacteria and fungi breakdown organic matter, extracting energy and releasing co2 to the atmosphere, and mineral nutrients to the soil
combustion - organic material reacts or burns in presence of oxygen. combustion releases co2 as well as sulphur dioxide and nitrogen oxide. naturally - wildfires are essential to health of some ecosystems. human actvities - fossil fuels release lots of co2 from lithosphere to biosphere and atmosphere.
natural sequestration [sequestration is long term removal and storage of carbon from the atmosphere, sequestration of carbon in oceans happens in 2 diff ways, biological and physical pump]
phytoplankton absorb atmospheric carbon during photosynthesis (biological pump). carbonate shells move into deep ocean water through the carbonate pump (cycling of organic matter in ocean), and action of thermohaline circulation (movement of seawater according to temperature) (physical pump).
weathering - breakdown of rocks at or near the surface of earth by chemical physical and biological processes. involves rainwater which contains dissolved co2 derived from soil. carbonation releases carbon from limestones to streams, rivers oceans and atmosphere. physical weathering increases surface area exposed to chemical attack. biological processes such as chelation contribute to rock breakdown.
the water and carbon cycles as open and closed systems
closed at global level - as water is not added or removed in a global level. there are no inputs or outputs only throughputs.
open at local level - water and carbon can move between different local ecosystems, causing these systems to be open, as there can be different inputs and outputs.
case study of a tropical rainforest (the Amazon Basin)
case study facts: worlds carbon 25% in amazonia, 50% of all rainforest in amazon
the processes and stores of the water cycle in tropical rainforests
high precipitation (convectional), high transpiration (due to high temperatures, abundant moisture and dense vegetation) high interception (due to tree cover), rapid run off, atmosphere stores large amounts of moisture (very humid), groundwater store large, vegetation (absorbs and stores water, releasing it as transpiration)
physical factors affecting flows and stores in the water cycle
temperature - convectional rainfall, in large amounts, as rainforest on equator increases levels of solar insolation. consistently high temperatures, no cold season, high precipitation though not consistent. water is cycled consistently between the land, trees and atmosphere through evapotranspiration and precipitation
geology - impermeable catchments (due to crystalline rocks) have minimal water storage resulting in rapid run off, permeable and porous rocks (e.g. limestone) store rainwater and slow run off
relief - most of amazon basin comprises extensive lowlands, in areas of gentle relief water moves across the surface (overland flow), or through soil (throughflow), to streams and rivers. in the west the Andes create steep catchments, rapid run off. widespread inundation across extensive floodplains (Pantanal) occurs annually, storing water for several months.
how natural and human factors have changed flows and stores of water cycle in the Madeira drainage basin
human - deforestation (since 1970 1/5 of primary forest has been destroyed or degraded) has reduced water storage in forest tees, soils and rocks and in the atmosphere, as well as decreasing evapotranspiration and therefore precipitation . Run off speeds increasing has raised flood risks (April 2014, madeira river flood killed 60 people, evacuated 68,000 and outbreaks of cholera). rainforest trees also stabilise albedo and ground temperatures, leading to permanent climate change. future deforestation has led to prediction of 20 percent decline in regional rainfall.
physical - most of amazon basin comprises extensive lowlands, in areas of gentle relief water moves across the surface (overland flow), or through soil (throughflow), to streams and rivers. in the west the Andes create steep catchments, rapid run off. widespread inundation across extensive floodplains (Pantanal) occurs annually, storing water for several months. most of amazon basin comprises extensive lowlands, in areas of gentle relief water moves across the surface (overland flow), or through soil (throughflow), to streams and rivers. in the west the Andes create steep catchments, rapid run off. widespread inundation across extensive floodplains (Pantanal) occurs annually, storing water for several months. convectional rainfall, in large amounts, as rainforest on equator increases levels of solar insolation. consistently high temperatures, no cold season, high precipitation though not consistent. water is cycled consistently between the land, trees and atmosphere through evapotranspiration and precipitation
the processes and stores of the carbon cycle in tropical rainforests
human factors to restore the rainforest
afforestation - replanting trees (committed to restoring 12 million hectares of forest through the 2015 Paris Agreement). reduces run off, nutrient and carbon loss, and infiltration. Sequesters carbon in trees, increases soil carbon and increases sequestration through photosynthesis.
agricultural techniques - more nutrients to the soil (rotational cropping, creation of dark earth [soils enriched with charcoal, compost, human wasta, and organic residues]. maintains soil fertility, reducing further deforestation, permanent cultivation reduces overland flow compared to abandoned farmland. reduced need for further deforestation so protects biomass store and dark soils retain fertility and maintain long term soil carbon store.
protecting the rest of the forest - protected areas (over 60% of the brazillian amazon is currently under conservation policy) . maintains interception and reduces run-off, maintains evapotranspiration and therefore maintains water balance and precipitation levels, preventing disruption to atmospheric moisture. prevents combustion through slash and burn, or removal of vegetation so maintains biomass store, maintains soil carbon, maintains carbon sequestration through photosynthesis (NPP remains positive).