Jannis - Environmental Management Flashcards
What is an environmental system?
A system can be defined as “a set of components functioning together as a whole”.
- System view allows to isolate and investigate certain aspects more closely.
- Given complexity of environment, engineers and scientists need to simplify to tractable size.
Systems can include one or more physical compartments and/or non-physical parts such as the economy
What are problems with burning coal (containing sulphur)?
Global warming
Acid rain
Changes in soil pH
How is our environment connected?
The environment is only moderately integrated (“loosely connected”) greatly hinders our ability to observed, predict, and ultimately correct the unintended consequences of our actions.
What are the 2 main divisions of environmental disruption?
Fundamentally, all environmental problems involve either depletion of sources (consumption) or pollution of sinks (production of waste).
Sinks:
Atmosphere - global warming, acid rain, urban smog
Ocean - pollution
Sources:
Ocean - overfishing
Rain forest - global warming, reduced biodiversity
What are the stages of scientific methods which scientists use to explore the
processes of the natural world?
1) Make observations
2) Ask a question
3) Gather existing information
4) Formulate a hypothesis
5) Collect and analyze data
6) Consult existing information
7) Discuss data and draw conclusions
8) Peer review
9) Publish
How may the entire environment of planet Earth be divided?
Into 4 spheres
• the biosphere (living organisms of Earth)
• the atmosphere (the gaseous envelope surrounding the planet)
• the hydrosphere (the liquid water on the surface of Earth) and
• the lithosphere (the stony or rocky matter composing the bulk of the
surface of Earth)
What is the energy system of Earth?
Earth system is open to energy. Most energy flows from the sun and is often radiated back into space.
For all practical purposes Earth is a closed system for matter.
If we discount the relatively small amount of matter added from meteorites and other space debris, Earth contains all matter that it will ever have.
Hydrosphere, lithosphere, atmosphere and biosphere can be further subdivided. For example the lithosphere can be divided into continental or oceanic crust, the pedosphere (outermost layer of Earth’s crust consisting of soil), asthenosphere (upper Earth mantle, below the lithosphere), and so on. These spheres are all interconnected and constantly exchanging materials.
What does integration refer to regarding environmental science?
What does complexity refer to regarding environmental science?
Integration refers to the strength of the interactions among the parts of the system. For instance, the human body is a highly integrated system, whose
cells are interdependent and in close communication.
Complexity is often defined as how many kinds of parts a system has.
What is the post industrial stage?
The next (future) stage of society has been called the post-industrial stage.
What form post-industrial society will take is open to speculation and debate, but two possible alternatives have been proposed.
One is a sustainable future where the human population stabilizes and technology becomes less environmentally harmful.
The second alternative is overshoot, where the human population climbs so high and technology is so harmful that the environment is degraded to the point that relatively few people can be supported, at least with decent standard of living.
What factors greatly hinder societal responses to environmental problems?
The moderate integration and high complexity of environmental systems.
Integration results from connectedness so that resource depletion or pollution of one part
of the environment can have cascading, or domino, effects into other parts.
For example, burning sulfur-rich coal affects the atmosphere as air pollution, but it also affects the hydrosphere, when it falls as acid rain to acidify lakes.
The biosphere is also affected because aquatic organisms in the lake can die due to the increased acidity of the lake water.
The burning coal can even affect the lithosphere when the acid rain dissolves limestone and other alkaline rocks to form caves and sinkholes.
Why may impacts on the environment be delayed and unpredictable?
Due to its integration and complexity
What is an ecosystem?
A community of organisms that interact with one another and with their physical environment, including sunlight, rainfall, and soil nutrients.
Organisms within an ecosystem tend to interact with one another to a greater extent than organisms between different ecosystems.
Within each ecosystem there are habitats, which are defined as the place where a population of organisms lives. (Population is defined as a group of organisms of the same species living at the same place at the same time.)
What occurs during positive feedback?
Positive feedback occurs when part of a system responds to change in a way that magnifies the initial change.
For example, evidence indicates that a slight increase in average global temperature can increase in the melting of glaciers and snow that reflect sunlight back into space. Instead of reflecting light, more of the Earth’s surface becomes available to absorb heat.
In nontechnical terms, positive feedback is
often referred to as a “snowball effect” or “vicious cycle”.
What is human impact (on the environment) a function of?
Population, affluence, and technology
What are primary producers?
Sunlight-consuming organisms.
Primary producers are autotrophic.
Since photosynthetic organisms obtain their carbon from inorganic sources, they are called photo-autotrophic.
What does trophic mean?
Trophic is the term used to describe the
level of nourishment.
How do aerobic, anaerobic, and anoxic organisms differ?
Organisms that are aerobic survive in oxygen-rich environments and use oxygen as the terminal electron acceptor.
Obligate aerobes can survive only in the presence of oxygen.
Anoxic environments contain low concentrations (partial pressure) of oxygen. Here nitrate is usually the terminal electron acceptor.
Anaerobic respiration can occur only in the absence of oxygen or nitrate. Here sulfate, carbon dioxide, and organic compounds that can be reduced serve as terminal electron acceptors.
What does NPP stand for?
What is NPP?
Net primary production.
NPP shows the rate of biomass production in a given ecosystem.
Some ecosystems such as tropical forest of a high NPP, whereas others such as deserts and tundra have a lower NPP.
What are some key features of the carbon cycle?
The ocean is the largest reservoir of carbon (85%).
Photosynthesis is a major driving force in the carbon cycle. The ocean is a major sink of carbon.
In shallow waters there is net consumption of carbon due to synthetic activity. In deeper waters there is net production of CO2 due to respiration and decay processes. Ocean circulation occurs over a long-time scale, the ocean takes up CO2 at a slower rate than produced by anthropogenic sources and its CO2 absorption capacity decreases due to increasing saturation.
What are some key features of the nitrogen cycle?
Nitrogen enters lakes usually in the form of nitrate (NO3-) from rivers or groundwater.
When taken up by algae, plants or phytoplankton,
the nitrogen is chemically reduced to NH2-R and incorporated into organic compounds. When dead biomass undergoes decomposition, the organic nitrogen is ultimately released as ammonia (NH3), at normal pH values in the form of ammonium (NH4+).
Ammonia from natural sources and other
sources such as industrial waste and agricultural runoff (e.g. fertilizers and manure) is oxidized to nitrate (NO3-) by nitrifying bacteria (Nitrosomonas / Nitrobacter)
What are biomes?
A large, naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or tundra.
What is the equation for photosynthesis?
6CO2 + 6H2O + 2800 kJ energy from sun
→ C6H12O6 + 6O2 [in presence of chlorophyll]
What are the 2 main bacteria responsible for nitrification?
Nitrosomonas and Nitrobacter
What are the reactions for nitrification?
Ammonia -> Nitrite and Nitrite -> Nitrate
Step 1:
4NH4+ + 6O2 ↔ 4NO2- + 4H2O + 8H+
Step 2:
4NO2- + 2O2 ↔ 4NO3-
Overall reaction:
NH4+ + 2O2 ↔ NO3- + 2H+ + H2O
What is denitrification?
What is the reaction for this?
Denitrification is the microbial process of reducing nitrate and nitrite to gaseous forms of nitrogen.
Under anoxic conditions, for example in anaerobic sediments, nitrate is reduced to nitrogen gas (N2) in a process called denitrification. Denitrification can also result in the formation of N2O (nitrous oxide).
2NO3- + organic carbon ↔ N2 + CO2 + H2O
What does symbiotic refer to?
The interaction between two different organisms living in close physical association.
What is required for certain microorganisms and plants to fix nitrogen from the atmosphere?
What is the chemical reaction for this?
ATP is required.
N2 + 8e- + 8H+ + ATP ↔ 2NH3 + H2 + ADP + Pi
Where Pi is inorganic phosphate.
What are some key features of the phosphorus cycle?
Phosphorous (P) in unpolluted waters is imported through dust in precipitation or via the weathering of rock.
P is normally present in watersheds at extremely low concentrations, usually existing dissolved as
inorganic orthophosphate, suspended as organic colloids, adsorbed onto particulate organic and inorganic sediment. The only significant form of phosphorous available to plants and algae is the soluble reactive inorganic orthophosphate species (HPO4 2-, PO4 3-).
During algal decomposition, phosphorous is returned to the inorganic form.
In stratified, oligotrophic lakes, P is permanently removed into the sediments of the lake.
What is an oligotroph?
What does oligotrophic mean?
An oligotroph is an organism that can live in an environment that offers very low levels of nutrients.
Oligotrophic: having a deficiency of plant nutrients that is usually accompanied by an abundance of dissolved oxygen.
How does stratification and turnover occur in deep lakes over the year / across the seasons?
During the summer, the surface water of a lake is heated both indirectly by contact with warm air and directly by sunlight.
Warm water, less dense than cool water, remains near the surface until mixed downward by turbulence
from wind, waves, boats, and other forces.
Because this turbulence extends only a limited distance below the water’s surface, the result is an upper layer of well-mixed, warm water (the epilimnion) floating on the lower water (the hypolimnion), which is poorly mixed and cool.
Because of good mixing the epilimnion will be aerobic. The hypolimnion will have lower dissolved oxygen concentration and may become anaerobic or anoxic.
The intermediary layer between epilimnion and hypolimnion is called the metalimnion. Within this region the temperature and density change sharply with depth.
The thermocline may be defined as the region having a change in temperature with depth that is greater than 1°C m-1
Once formed, lake stratification is very stable.
As temperatures drop, the epilimnion
cools until it is denser than the hypolimnion. The surface water sinks, causing overturning and the lake becomes mixed. This process stops if the water temperature reaches 4°C, as water at this temperature is densest.
Further cooling or freezing leads to winter stratification. In spring as water warm complete turnover occurs again.
How does oxygen concentration vary in the different layers of a stratified lake?
Because of good mixing the epilimnion will be aerobic. The hypolimnion will have lower dissolved oxygen concentration and may become anaerobic or anoxic.
What are the regions of a stratified lake?
Epilimnion - the uppermost layer of warm, well-mixed water. This region will be aerobic.
Metalimnion - the intermediary layer between epilimnion and hypolimnion.
Hypolimnion - the lowest level, which is cool and poorly mixed.
Thermocline - within the metalimnion . This layer may be defined as the region having a change in temperature with depth greater than 1°C m-1.
What are the important, distinct zones found in temperate (mild) lakes?
The most important zones are the euphotic, limnetic, littoral, and benthic zones.
Lakes contain several distinct zones of biological activity, largely determined by the availability of light and oxygen.
What is the Limnetic zone (regarding biological zones of temperate lakes)?
The Limnetic zone is the open water where photosynthesis can occur, dominated by floating organisms and actively swimming organisms.
Producers in this zone are planktonic algae. Primary consumers are zooplankton. The secondary consumers are swimming insects and fish.
What is the Euphotic zone (regarding biological zones of temperate lakes)?
The zone through which light can penetrate; its depth is determined by sunlight penetration (light levels greater than 0.5 - 1% compared to surface).
At poorer light conditions algae cannot grow.
What is the Littoral zone (regarding biological zones of temperate lakes)?
The shallow water near the shore in which rooted (emergent) plants can grow.
It’s extent depends on the slope of the lake bottom. It cannot extent deeper than euphotic zone.
What is the Benthic zone (regarding biological zones of temperate lakes)?
The bottom sediments, died organisms settle here, bacteria and fungi are always present.
Presence of higher life forms such as worms, aquatic insects, molluscs and crustaceans depends on the availability of oxygen.
What is lake productivity?
Productivity of a lake is a measure of its ability to support aquatic life.
It is often determined by measuring the amount of algal growth that can be supported by the available nutrients. The productivity forms a basis for classifying lakes.
What is a Secchi disc (& Secchi depth)?
A Secchi disc is an opaque disc, typically white, used to gauge the transparency of water by measuring the depth - known as the Secchi depth - at which the disc ceases to be visible from the surface.
What is Leibig’s law of the minimum?
The law stating that growth is dictated by the scarcest resource (limiting factor), and not by the total resources available.
What are the different classifications of lake?
Oligotrohpic - host very little or no aquatic vegetation and are relatively clear. Few nutrients.
Mesotrophic - have moderate alkalinity and nutrient levels, which result in a high diversity of aquatic plant and macroinvertebrate species.
Eutrophic - where of a water body has lost so much of its dissolved oxygen that normal aquatic life begins to die off.
Hypereutrophic - very nutrient-rich lakes characterized by frequent and severe nuisance algal blooms and low transparency.
From top to bottom (O to H):
Chlorophyll conc’: increases (i.e. more algal blooms)
Secchi depth: decreases (i.e. visibility/clarity decreases)
P conc’: increases
What is the basic phosphorus balance on a lake?
VdP/dt = P(in)Q(in) - kP(out)*V - P(out)Q(out)
Where:
- k is the phosphorous removal rate
- Q is flow rate
- P is phosphorus conc’
At s.s. dP/dt = 0
If the removal rate (sometimes called the settling velocity where it does not include biological uptake) is given in units of distance per time (e.g., m s-1), the velocity should be multiplied by the surface area of the lake, rather than the volume.
What are population dynamics?
Why are they important?
Population dynamics is the study of the changes in the numbers and composition of individuals in a population within a study area and the factors that affect these numbers.
For environmental engineers evaluating population dynamics is critical to
1) understand how environmental perturbations affect populations
2) predict human populations for example to determine water resource needs
3) predict bacterial populations in engineered systems
4) use as indicators for environmental quality
Resource development specialist and wildlife biologists use population dynamics to
1) estimate how many animals can be harvested
2) predict when a species is threatened or endangered with extinction
3) understand species interaction (competition or predation)
How may the population of bacteria after the nth generation be calculated?
P = P(0)*2^n
Where:
P is population
P(0) is initial population
n is the number of generations
How is the change in numbers of animals within a population per unit time calculated?
N = N(0)e^(rt)
Where r is the specific rate of change
Define environmental science. What relevance does it have to people?
Environmental science, interdisciplinary academic field that draws on ecology, geology, meteorology, biology, chemistry, engineering, and physics to study environmental problems and human impacts on the environment.
Environmental science is a quantitative discipline with both applied and theoretical aspects and has been influential in informing the policies of governments around the world. Environmental science is considered separate from environmental studies, which emphasizes the human relationship with the environment and the social and political dimensions thereof.
Give some basic examples of causes of environmental problems:
Global warming, local air pollution in an urban area, desertification, microplastics pollution of the ocean, decrease of insects across Europe, eutrophication of lake, collapse of fisheries, disappearance of wetlands across the world, drying out of lakes and rivers.
Global warming, local air pollution, microplastics pollution, decrease of insects, eutrophication of lake are all examples that overwhelm the natural cleaning capabilities of the environment by pollution.
Desertification, collapse of fisheries, disappearance of wetlands, lake and rivers are due to the overuse of resources that cannot be renewed as fast as they are used up.
What is the first law of ecology?
Everything Is Connected to Everything Else. There is one ecosphere for all living organisms and what affects one, affects all.
What is the second law of ecology?
Everything Must go Somewhere. There is no “waste” in nature and there is no “away” to which things can be thrown. Any waste produced in one ecological process is recycled in another. A core principle for the Circular Economy.
What is the third law of ecology?
Nature Knows Best.
Humankind has fashioned technology to improve upon nature, but any human change in a natural system is, says Commoner, “likely to be detrimental to that system” And in the context of chemicals of concern we are looking to eradicate from buildings (through eg the ILFI Red List) “The absence of a particular substance in nature, is often a sign that it is incompatible with the chemistry of life”
What is the fourth law of ecology?
There Is No Such Thing as a Free Lunch. Exploitation of nature, will always carry an ecological cost and will inevitably involve the conversion of resources from useful to useless.
What are the 4 laws of ecology?
- Everything is connected to everything else
- Everything must go somewhere
- Nature knows best
- Nothing comes for free (i.e. exploiting nature will always have a cost)
Pick two of the 18th/19th century explorers mentioned in the lecture and research how their activities contributed to our modern understanding of the environment:
Georg Foster: botany, ethnology, modern travel literature (not direct contribution to environmental science and understanding of environment).
Charles Darwin: principles of natural selection (principles of evolution).
Joseph Hooker: mostly botany and defender of Darwin’s theory.
What are the five basic developmental stages in the relationship between people and the environment? Briefly describe each:
The five stages are Gathering and Hunting, Agriculture, Industry, Transition and Post-industrial.
Gathering and Hunting: Early humans were at mercy of their environments, weather, predators, disease etc. Population was relatively low and human-induced effects on the environment were localised.
Agriculture: Shift from hunting and gathering to cultivating food. This allowed increased populations and more people living in cities. However, land became an exploited resource and wilderness vanished.
Industry and environmentalism: Population grew faster with industrialisation, environment seen as both source of raw materials and place to dispose waste and by-products of industry. The result was a rapid decrease in air and water pollution, as well as problems with solid and hazardous waste disposal. At the end of this stage, pollution became so widespread that antipollution social movements emerged: The classic “environmentalism” movement.
Transition and sustainability: This is the transition stage since humanity must now decide how to act to determine the long-term fate of the environment.
Post-industrial: The next (future) stage of society has been called the postindustrial stage.
What form postindustrial society will take is open to speculation and debate,
but two possible alternatives have been proposed. One is a sustainable future
and the second is overshoot, where the population becomes too great and technology is harmful.
Explain the concept of ‘Commons’:
How does it apply to environmental issues?
Biologist Garrett Hardin argued that property that many people hold in common will be destroyed or at least overused until it deteriorates.
As a simple example one can imagine a pasture where herdsmen of a village can keep their cattle. Each cow that an individual herdsperson adds will benefit the owner, but the community will bear the cost of overgrazing. Because the benefit of adding another cow goes to the individual and the cost of overgrazing goes to the community, the “rational” choice of everyone is to add cows. Thus, the commons rewards behaviour that lead to deterioration, such as overgrazing, and punishes individuals who show restraint.
What is the precautionary principle?
The precautionary principle states that in the face of uncertainty the best course of action is to assume that a potential problem is real and should be addressed.
Better safe than sorry!
However, the precautionary principle acknowledges that urgent environmental problems exist and that these problems need to be addressed within the next few years, or at least decades, or they may lead to large-scale environmental degradation and overshoot.
Define the terms ecosystem and ecology. What are the differences in these terms?
Ecosystem - a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life.
Ecology - the study of organisms and how they interact with the environment around them.
Ecology studies the different ecosystems
Describe the difference between a food web and an ecological pyramid:
A food web is multiple food chains and an energy pyramid shows how energy moves through trophic levels.
What is ‘carrying capacity’, K?
The numbers of individuals an area
can support.
What are the 5 major processes occurring within the nitrogen cycle?
Fixation, uptake, mineralization, nitrification, and denitrification – all driven by microorganisms.
What are the 5 major steps of the phosphorus cycle?
Weathering Fertilizer Excretion and decomposition Dissolved phosphates Geologic uplift
How does the P cycle differ to other nutrient cycles?
The phosphorous cycle differs from other nutrient cycles, because it never passes through a gaseous phase like the nitrogen or carbon cycles.
What is natural and cultural eutrophication?
Eutrophication - excessive richness of nutrients in a lake or other body of water which causes a dense growth of plant life.
Natural eutrophication has been occurring for millennia. It is the process of addition, flow and accumulation of nutrients to water bodies resulting in changes to the primary production and species composition of the community.
Cultural eutrophication occurs when human water pollution speeds up the aging process by introducing sewage, detergents, fertilizers, and other nutrient sources into the ecosystem.
What are the phases of bacterial growth?
Lag Acceleration (log) Growth Stationary Death
What factors determine the number of a particular species in the wild?
- Density - dependent factors as the availability of food, locations to live and build nest for their young, concentration of toxic waste products, disease, predators, parasite, and so on.
- Environmental factors such as weather, temperature,
flooding will affect population dynamics.
What 5 components explain changes in population?
Birth Death Gender ratio Age structure Dispersal
What is the simplest model for animal population dynamics, assuming exponential growth and that there are limited resources?
dN/dt = rN
Where r is specific rate of change and N is number
The value of r can be found by plotting ln(N/N0) vs t.
What is the model for animal population dynamics, assuming that there is a limited amount of food and space?
N(t+1)/N(t) = λ = e^r
What is the model for animal population dynamics, assuming resource limitation?
A logistic growth model, which adds a density dependent term to describe the limitations that exist, is more useful than the simple model.
This model includes a term called the carrying capacity, K, which is simply the numbers of individuals an area can support. As the numbers approach K, the mechanisms (increased mortality, decreased reproduction, increased dispersal) that result in a decrease in the rate of population growth take over.
dN/dt = rN[(K-N)/K]
N(t) = KN0/(N0 + (K-N0)e^(-r*t))
What models explain the relationship between the number of predators, K, and prey, P?
dP/dt = aP - bPK
dK/dt = cPK - dK
Where: a = growth rate of the prey b = mortality parameter of the prey c = growth rate of the predator d = mortality parameter of the predator
These equations are often referred to as the Lotka-Volterra model and result in a cycling nature.
What are some examples of human activities which can have an impact on ecosystems and the
abundance of species?
- Large scale agriculture results in release of pesticides, fertilizers, carbon dioxide and other greenhouse gases.
- Hydroelectric power plants can have detrimental effects on river ecosystems.
- Release of chemicals such as (DDT), heavy metals, acid rain can have wide ranging effects.
- Introduction of non-native (exotic, invasive) species can destroy ecosystems and kill native species.
- Excessive hunting.
- Habitat disruption.
What are some causes of population growth and decline?
Cause of growth:
Increase available resources - Nutrient pollution in lakes
Competitive release - Poisoning of insect pests (competitors are killed)
Predator release - Overhunting of large carnivores
Introduce to new areas - Game release
Cause of decline: Habitat disruption (physical) - Draining a swamp, toxic pollution
Introduce new species (biological) - New predator / competitor
Overkill - Big-game hunting
Secondary extinctions - Loss of food species
Soils have six key parts in providing ecosystems services. State these 6 ways:
• Soils support plant growth, by providing habitat for plant roots and nutrient elements for the entire plant. Soil properties often determine the nature of the vegetation present and indirectly, the number and
types of animals (including people) that the vegetation can support.
- Soils regulate water supplies. Water loss, utilization, contamination, and purification are all affected by the soil.
- Soil functions as nature’s recycling system. Within the soil, waste products and dead bodies of plants, animals and people are assimilated, and their basic elements are made available for reuse by the next generation of life.
- Soils are alive and inhabit small mammals and reptiles, insects, microorganisms in large number and diversity.
- Soils influence the composition of the atmosphere by taking up and releasing, CO2, O2 and other gases and by contributing dust and re-radiated heat to the air.
- Soils are an important engineering medium by providing building material (earth fill and bricks) and providing the foundation for roads and houses.
What is soil?
A combination of weathered, disintegrated, decomposed rocks and minerals (technically known as regolith) plus the decayed remains of plants and animals (organic matter and humus); small living animals, plants, fungi, bacteria and other microscopic organisms; water; and air.
For all purposes, soil is alive. Typical soil is about 50% mineral and organic matter by volume and about 50% of water and air.
What are some threats towards soil?
Soil availability - In most parts of the world nearly all soils best suited for growing crops are already being farmed.
Soil degradation - Erosion (water, wind), overgrazing, top-soil loss, desertification, chemical contamination, soil quality decline, mismanagement of forests, farms, and rangeland.
Competition with natural ecosystems.
Chemical contamination and soil quality decline.
In the scale of human lifetimes they cannot be considered a renewable resource. Soils need thousands of years to develop.
What is a horizon, regarding soil?
Examination of a vertical section of a soil, as seen in a roadside cut or in the walls of a pit dug in the field, reveals the presence of more or less distinct
horizontal layers.
Such a section is called a profile, and the individual layers are known as horizons.
What are the 5 horizons of soil?
O - Litter A - Litter and topsoil B - Subsoil C - Transition zone D - Parent material
How are igneous, sedimentary, and metamorphic rock formed?
Igneous rock, formed by the cooling of magma (molten rock) inside the Earth or on the surface.
Sedimentary rocks, formed from the products of weathering by cementation or precipitation on the Earth’s surface.
Metamorphic rocks, formed by temperature and pressure changes inside the
Earth.
What are features of the soil horizons?
The all organic O-horizon does not occur in all soils but for example in forest soils. The uppermost layers of horizon of a soil profile are darker in colour than the lower horizons. This difference is due to the accumulation of organic matter that results from the decay of plant roots and of other organic
residues incorporated into the upper soil layers.
Also weathering tends to be more intense in the upper horizon than in the lower layers.
Some products of weathering have been leached out of these upper layers, which are collectively termed the A horizons.
The underlying layers contain comparatively less organic matter than those nearer the surface. They are characterized by an accumulation of varying amounts of substances such as silicate clays, iron and aluminium oxides, gypsum, and calcium carbonates. These materials may have been washed down from upper layers or they may have been formed in place through the weathering process. These underlying layers are referred to as B horizons.
The C horizon is a transition zone between which is often composed of unconsolidated parent material, i.e. weathered, partially decomposed rock.
Collectively, these horizons make up the solum of the upper part of the profile above the parent material (D horizon). The solum extends to a depth of 1 – 2 meters in temperate region soils, highly weathered soils of the tropics may be much deeper.
What does solum mean?
The altered soil or material overlying the parent material, often including the A-horizon and the B-horizon.
What factors affect soil formation?
- Climate (particularly temperature and precipitation)
- Living organisms (especially native vegetation, microbes, soil animals, and human beings).
- Nature of parent material
- Topography (physical arrangement) of the site.
- Time that parent material was subjected to soil formation.
What are the main processes involved in soil genesis?
- Weathering and organic matter breakdown, by which soil constituents are modified or destroyed and others are synthesized
- Translocation of inorganic and organic materials up and down the soil profile, the materials being moved mostly by water but also by soil organisms
- Accumulation of soil materials in horizontal layers in the soil profile.
What do mineral soils contain?
A mineral soil is a physical mixture of inorganic particles, decaying organic matter, air and water. The larger mineral fragments are usually embedded in
and coated with clay and other colloidal materials.
What is the particle density, bulk density, and pore space of mineral soils?
Particle density - the mass of a unit volume of soil solids and is called particle density (Dp).
Bulk density - Db is the weight of the solid particles in a standard volume of field soil (solids plus pore space occupied by air and water).
Pore space - the pore space (in %) is that portion of the soil volume occupied by air and water.
What pH of soil can be found?
Soils can be acidic, neutral or alkaline. Soil acidity is common in all regions where precipitation is high enough to leach appreciable quantities of exchangeable base-forming cations (Ca2+, Mg2+, K+ and Na+) from the surface layers of soil.
Alkalinity occurs in the presence of base-forming cations such as calcium, magnesium, and sodium carbonates, some soils can reach a pH of 9 or even
10. Alkaline soils are characteristic of arid and semiarid regions.
The soil pH significantly affects the availability of most of the chemical elements of importance to plants and microbes.
What is arable land?
Arable land is land that is or that can be cultivated. Agriculturally productive land consists of arable land and that which is not arable but is suitable for grazing.
What organisms assist with nitrogen fixation (into soils)?
- Symbiotic systems, nodule forming (obligatory)
a) with legumes
b) with non-legumes - Symbiotic systems, non-nodule forming (associative)
- Non-symbiotic systems
What are the 2 main issues with practical management and control of nitrogen in soils?
- The maintenance of and adequate nitrogen supply in the soil.
- The regulation of the soluble forms of nitrogen to ensure a ready availability to meet crop demands, while avoiding leaching and atmospheric loss.
What are the two ways in which water (vapour) is lost from soils?
Vapour losses of water from soils occur by evaporation (E) at the soil surface and by transpiration (T) from the leaf surfaces.
The combined loss resulting from these two processes, termed evapotranspiration (ET).
What is evapotranspiration and what does it depend on?
Vapour losses of water from soils occur by evaporation (E) at the soil surface and by transpiration (T) from the leaf surfaces. The combined loss resulting from these two processes, termed evapotranspiration (ET).
Evapotranspiration is dependent on radiant energy by the sun, atmospheric vapour pressure, temperature, wind and soil moisture content of the soil.
What is the water efficiency (T efficiency) of a crop?
The kg water transpired to produce 1kg of dry matter.
What practises affect the efficient use of water, regarding water management for soils?
- Those that increase the amount of water entering the soil and remaining there until taken up by plants.
- Those that increase crop production per unit of water taken up by plants.
What is tillage?
The preparation of land for growing crops.
What measures have been made to control wind erosion on croplands?
Conservation tillage, planting windbreaks, and tilling at right angles to the prevailing winds, so that furrows act as small windbreaks to capture blowing soil.
What are the major factors affecting accelerated soil erosion, mentioned in the universal soil loss equation?
A = (R)(K)(LS)(C)(P)
Where: A = predicted soil loss (in Mg ha-1) R = rainfall erosion index K = soil erodibility factor LS = topographic factor, a function of L = length in m; S = slope (%) C = crop management factor P = conservation practice factor
What are the 6 general kinds of pollutants that commonly reach soil?
Pesticides
Inorganic pollutants (e.g. mercury and lead)
Organic waste (e.g. from food-processing plants)
Salts
Radionuclides
Acid rain
How do pesticides move within soils?
In 6 major directions:
- Vaporize into atmosphere without chemical change.
- Adsorbed by humus and clay.
- Move downward in liquid or solution and be lost from soil by leaching.
- Undergo chemical reaction within or on surface of soil.
- Broken down by microorganisms.
- Adsorbed by plants, and potentially detoxified
If soils are contaminated with pesticides addition of easily degradable organic matter can help to bring levels down. Growth of high-nitrogen cover crops or addition of large quantities of animal manures should be also helpful.
