Humans and their effect on the Biotic World
Through our increasing numbers, increasing land use and increasing pollution, we are outcompeting the animal world. While global biodiversity is difficult to quantify, it is decreasing rapidly due to ______ ______.
human activity
The _________ cycle is a system of water flows and storages driven by solar radiation.
hydrological
Soil may be illustrated by a soil profile that has a layered structure known as ___ _________.
- O - organic horizon
- A- mixed mineral-organic horizon
- E- Eluvial or leached horizon
- B- illuvial or deposited horizon
- C- Bedrock or parent material
- R- Bedrock
soil horizons
Due to both increased human population and improved diets, there is growing pressure on our soils. Socio-economic, cultural, ecological, political and economic factors can be seen to influence societies in their choices of food production systems. To meet the demand, commercial, industrialised food production systems (which generally tend to reduce soil fertility) are replacing small-scale subsistence farming ________.
methods
The atmosphere is predominantly a mixture of _____ (78.1%), ______ (20.9%), ______ ______ (0.4%), argon, water vapour and other trace gases.
nitrogen, oxygen, carbon dioxide
The human activities that cause species _________ include:
- Habitat destruction
- Introduction of invasive species
- pollution
- over-harvesting and hunting
extinctions
The water in our oceans is constantly circulating, driven by differences in temperature and salinity which effect the density of sea water. Warmer, less salty water rises and colder, saltier water sinks. These thermocline currents move water in a global loop known as the great _____________________.
oceanic conveyor belt (OCB)
Soil can also be classified using a ____ ______ _______ which illustrates the composition of the soil based on the percentage of sand, silt, and clay. This composition is a good indication of the properties of the soil such as: mineral and nutrient content, drainage, water-holding capacity, air spaces, biota and potential to hold organic matter; and therefore can help to determine the ability of the soil to promote primary productivity.
soil texture triangle
The sustainability of terrestrial food production systems is influenced by ________ such as:
• scale
• industrialisation
• mechanisation
• fossil fuel use
• seed, crop and livestock choices
• water use
• fertilisers
• pest control
• pollinators
• antibiotics
• legislation
• ratio of commercial versus subsistence food production
factors
The stratosphere (10 km–50 km) which contains the ______ layer and the troposphere (less than 10 km) where most clouds form. As we saw in the first chapter both of these layers are important for the solar radiation in the planet with clouds affecting albedo levels and trapping heat.
Ozone
____________ is the variety of all living organisms on Earth—including genes, species, and ecosystems—vital for ecosystem resilience, human survival, and climate regulation. It provides critical services like food, oxygen, and medicine, but faces massive threats from human activity.
biodiversity
Up to 40% of humans alive today live with some level of freshwater scarcity. Either:
_______ scarcity of water – there is not enough water.
_______ scarcity of water – there is enough water but it is too expensive to access.
physical, economic
Soil can be considered a _______, where most of our food production grows from soil.
Inputs: organic material including leaf litter and inorganic matter from parent material, precipitation and energy
Outputs: uptake by plants and soil erosion
Storages: organic matter, organisms, nutrients, minerals, air and water
Flows: Transfers of material within the soil, including biological mixing and leaching (minerals dissolved in water moving through soil), contribute to the organization of the soil. Transformations include decomposition, weathering and nutrient cycling.
system
It should be apparent that our current approach is unsustainable. The solution is to reduce the demand on the soils and better conserve them. Increased sustainability may be achieved through: _____ human activity, _______ release of pollutant, Clean-up and _______ of damaged systems.
altering, controlling, restoration
Stratospheric ozone is a key component of the atmospheric system because it protects living systems from the negative effects of _______ radiation from the Sun. This radiation reaching the surface of the Earth damages human living tissues, increasing the incidence of cataracts, mutation during cell division, skin cancer and other subsequent effects on health. The effects of increased ultraviolet radiation on biological productivity include damage to photosynthetic organisms, especially phytoplankton, which form the basis of aquatic food webs.
ultraviolet
__________ is the act of preserving something for future generations. It is a two stage process. First vulnerable species and/or habitats are identified, then strategies are put in place to protect them.
conservation
_________ species are organisms whose presence, absence, or population status reveals the specific health, quality, or changes in an environment.
indicator
_____ soil – low primary productivity due to poor water-holding capacity and low
nutrient status.
____ soil – quite low primary productivity due to poor aeration and poor water infiltration.
_____ soil – high primary productivity due to medium infiltration rate, water-holding capacity, nutrient status, aeration, and ease of working.
sandy, clay, loam
__________ – To irrigate crops, humans have diverted rivers, and extracted water from surface stores and ground water. Furthermore cropland and grazing pastures intercept less rain and allow for less infiltration. Combined this can lead to greater surface runoff, leaching of minerals and flooding. Agricultural chemicals can be carried in the runoff and discharged into rivers.
Agriculture
Human activities have disturbed the dynamic equilibrium of stratospheric ozone formation. Ozone depleting substances (including halogenated organic gases such as ___________) are used in aerosols, gas-blown plastics, pesticides, flame retardants and refrigerants. Halogen atoms (such as chlorine) from these pollutants increase destruction of ozone in a repetitive cycle, allowing more ultraviolet radiation to reach the Earth.
chlorofluorocarbons CFCs
Conservation of biodiversity steps:
1. _______: Quantification of biodiversity.
2. _______:Designating a species or habitat with a special status (ex: endangered species IUCN Red List, national park) can help to publicise the need to protect it.
identify, select,
_____________ — excessive nutrient enrichment, often from leached agricultural fertilisers, leading to rapid growth in algae, plants and phytoplankton populations.
______________- measures the amount of dissolved oxygen microorganisms need to decompose organic matter in water, serving as a key indicator of pollution.
eutrophication, Biochemical Oxygen Demand (BOD)
Humans can severely _______ soils through urbanisation (compactions), mining, deforestation, and intensive agriculture (grazing, monoculture, over irrigation). The loss of vegetation makes the soils more prone to erosion and the leaching of minerals.
degrade
_________ – trees intercept large volumes of precipitation and their roots stabilise the soil, increasing the volume of water infiltrated into the ground. When they are removed most of the precipitation becomes surface runoff, eroding the soil and raising flood levels. If not quickly replenished with new vegetation, a positive feedback loop forms as the soil becomes degraded, vegetation decreases and surface runoff increases.
__________ – The effects can vary from city to city. In general urban areas have more impermeable areas and less vegetation. During dry periods, evaporation is increased and more strain put on water stores, depleting aquifers/lowering the water table; where as, in wetter periods, surface runoff and the chance of flash floods increases. This can be offset by greater water management such as: diverting rivers, building storm drains and urban basins and encouraging the use of urban greenery and permeable surfaces. However, these measures sometimes just move the problem downstream.
deforestation, urbanization
The ______ _______ ___ _________ ___ ______ ___ _______ _____ (1987) and subsequent updates is an international agreement for the reduction of use of ozone-depleting substances signed under the direction of UNEP. National governments complying with the agreement made national laws and regulations to decrease the consumption and production of halogenated organic gases such as chlorofluorocarbons (CFCs). Methods for this reduction include: altering human activity, controlling release of pollutant, clean-up and restoration of damaged systems.
Montreal Protocol on Substances that Deplete the Ozone Layer