Environmental Science PDF

Environmental Science Behind the many direct causes of environmental issues, we find that there are common, underlying **indirect drivers**: - Human population growth - Dependence on fossil fuels for transport, electricity, industry - Consumerism/materialism -- unsustainable production and...

Environmental Science Behind the many direct causes of environmental issues, we find that there are common, underlying **indirect drivers**: - Human population growth - Dependence on fossil fuels for transport, electricity, industry - Consumerism/materialism -- unsustainable production and consumption patterns - Poverty and conflict - Degradation of common property (owned by nobody but accessible to all unless well regulated: air, sea, fish, land, forests etc.) **Sustainable development** Development of a country: **an improvement in quality of life of its people**. If development brings about damage to Earth's life support systems, it is unsustainable. Sustainable development: **development that meets the needs of the present generation without compromising the ability of future generations to meet their own needs.** (Brundtland report 1987) Sustainable development is based on integrating **three pillars** of human development: - Social progress (justice and quality of life) - Economic growth (generation of enough wealth to live well) - Environmental responsibility (caring for our planet) In 2015 the United Nations adopted Agenda 2030, based on 17 Sustainable Development Goals. These SDGs aim to achieve more sustainable\_ development, improving people\'s quality of life while protecting climate and biodiversity. **Natural Resources** Like any other organism, humans depend on natural resources. All humans' needs must be met from the environment. **Natural resource**: any substance, form of energy or object found in the **natural environment** that is **useful to any living organism**. (ex: air, water, soil) Natural resources are either: - **Biotic**: living resources -- crops, fish, trees - **Abiotic**: non-living resources -- metals, fossil fuels, wind, soil, flowing water Natural resources can be: - **Renewable resources** - these are resources that continue to exist despite being consumed or can replenish themselves as they are used. They include things like the sun, wind, and water as well as biotic resources that renew themselves through reproduction and growth. - **Non-renewable resources** - These are finite resources that do not replenish themselves, at least on human timescales, and are depleted by consumption. They include fossil fuels, metals and other minerals **Earth's structure**  **The CRUST** This is the outermost layer of Earth. It can be divided into: **Continental crust**: the solid layer of rocks that make up the continents and the continental shelves (shallow seabed close to the shore) **Oceanic crust**: that part of Earth's crust that forms the ocean bed. Earth's crust has a variable thickness. Continental crust is: **THICKER** but **LESS DENSE** than oceanic crust Continental crust and oceanic crust also differ in composition, since different rock types predominate. Continental crust is mainly made up of granites while Oceanic crust is mainly made up of basalts. **Both are igneous rocks**. The crust is made up of many elements (that are often combined with other elements forming compounds) but the most common are oxygen silicon and aluminium (in that order). **Continental crust** **Oceanic crust** ----------------------- --------------------------- THICKER LESS THICK LESS DENSE DENSER Made up of granites Made up of mainly basalts **The Mantle (HOTTEST)** This is a very thick layer (about 2900km) found beneath the crust. It **makes up most (84%) of the Earth's volume**. While there are various elements present it is mainly made up of oxides of SILICON and MAGNESIUM. Much of Earth's internal heat is found in the mantle, with temperatures of up to 4000◦C towards the bottom of the mantle (near the core) The Mantle can be further sub-divided into two parts: - **The upper mantle**: this consists of a solid layer below which is a layer of slow-flowing molten material (the asthenosphere) - **The lower mantle**: this is thought to be solid despite the very high temperatures because of the high pressures involved. **The CORE** This is separated into the: - **The outer core**: is a dense molten layer about 2300 km thick. It is composed mainly of molten iron and nickel. The outer core controls Earth\'s magnetic field. - **The inner core**: is 1200 km thick. It is a solid mass mainly made up of iron and nickel. The core is the hottest part of Earth with temperatures thought to be up to 6000°C The rigid, outermost part of Earth is known as the **lithosphere**. This \'floats\' on a semi-solid, plastic (can flow) layer known as the **asthenosphere** (Part of the upper mantle) **Lithosphere**: the rigid outermost part of Earth, consists of the crust and the solid outermost part of the mantle. **Asthenosphere** - a semi-solid, region of the upper mantle made up of partly molten rock that lies just below the lithosphere. **Plate tectonics** Plate tectonics: a scientific theory that explains natural phenomena such as earthquakes, volcanic eruptions, mountain building and the formation of mid-ocean ridges and ocean trenches. According to this theory the lithosphere is made up of seven major and several minor tectonic plates. These are massive rigid bodies of rock overlying the asthenosphere. These are in continuous, slow movement due to convection currents within the asthenosphere. Plate motion is slow (2-10cm per year) but over millions of years this results in massive changes in Earth's land masses. In fact, about 200 million years ago, there were no continents as we know them today, but just one huge super continent called **Pangea**. Plate boundaries (or plate margins) are the edges of the lithospheric plates, where plates interact with other plates resulting in earthquakes, volcanic activity, mountain building and other natural phenomena. Three main types of plate boundaries: - **Divergent boundarie**s (constructive boundaries) - **Convergent boundaries** (destructive boundaries) - Igneous rocks - Sedimentary rocks - Metamorphic rocks - These are rocks made from solidified magma. - Igneous rocks are by far the most common rocks on Earth. They include **basalts** (extrusive rocks formed by the quick cooling of surface lava) and **granites** (intrusive rocks formed by the slow cooling of magma trapped below Earth's surface). 3 types: 1\. Chemical weathering. 2\. Physical weathering. 3\. Biological weathering. **Physical weathering** (also known as mechanical weathering) involves the breakdown of rocks by physical prossess. Temperature changes cause repeated expansion and contraction of rock material, causing rocks to weaken and crack. Water is a major cause of mechanical weathering, for example freeze-thaw weathering which results from water within rocks expanding as it freezes and becomes ice. **Chemical weathering** involves chemical reactions between rock material and environmental chemicals such as oxygen, carbon dioxide, and water. These reactions produce substances that can make the rocks weaker. **Biological weathering** involves plants and animals. As trees grow roots can dig in and wedge rocks. Lichens (algae and fungi living together) slowly break down rock surfaces on which they grow. Burrowing animals expose rocks, increasing weathering. **Erosion** Erosion: is the process by which the Earth's surface is worn away. It is generally caused by moving water (streams, rivers, waves etc) and wind. Weathering and erosion take place together, but unlike weathering, erosion involves the physical removal of material. Erosion transports material away from the side. Biogenic sedimentation: the Maltese Islands Sometimes sediments of marine origin may contain large amounts of hard remains of dead organisms. This type of sedimentation is known as **biogenic sedimentation** (biogenic = of biological origin) Various marine organisms, (such as some microscopic plankton, coralline algae, sea urchins, seashells, and crabs) take up calcium and carbonate ions from the water to make shells, bones and other hard parts of their body. After death, these organisms decompose but the hard, calcareous parts may accumulate in sediments on the sea-bed Plankton -- organisms living in water but are not free swimming and are moved around by currents. Over time, these biogenic sediments can become sedimentary rocks through cementation and lithification. These rocks that make up the Maltese Islands are all typed of limestone formed by this process of biogenic sedimentation. The earliest sediments were laid down in the sea about 30 million years ago. This process of sedimentation continued until the Maltese islands were eventually raised above the sea about 6 million years ago.  The different strata reflect changes in the seabed environment when the sediments were deposited. Upper coralline limestone and lower coralline limestone are both thick layers of hard rock largely made up of remains of coralline algae that live in shallow, well-lit waters. Globigerina limestone is a thick layer full of fossils of tiny calcifying plankton that were deposited in deeper waters. Blue clay was also laid down in deep waters but contains a higher proportion of fine clay particles derived from land. Greensand is a thin layer containing minerals and fossils resulting from the erosion of sediments in strong currents as the sea was becoming shallower. Due to erosion, not all rocks are found everywhere -- over much of the Maltese Islands, globigerina limestone is the surface rock. **The Rock cycle**: Matter is neither created nor destroyed. So, rocks are not destroyed. They are broken down and changed over a long period of time through physical and chemical processes. The processes that change rocks from one type to another are collectively known as the rock cycle. The rock cycle is the slowest of the earth's cyclic processes since the rock cycle recycles material over millions of years. Igneous rocks are formed by the cooling and solidification of magma. Igneous and sedimentary rocks become metamorphic rock due to heat and pressure. Once exposed to the environment, all rock types can be converted to sedimentary rock through the processes of weathering, erosion, transport, deposition, cementation and lithification. Deep within the earth's lithosphere, especially at subduction zones, rocks melt, again becoming magma. 2\. Subsidence is the downward movement of the ground. When coal and minerals are extracted from beneath the ground, the land above can move downwards and fill the hollow mine workings. This can cause movement on the surface. 3\. Flooding -- Deforestation and habitat clearance caused by mining results in reduced absorption of water, increasing runoff that can lead to severe flooding. Surface mining also results in soil erosion with unconsolidated soil which can find its way into rivers. This causes siltation, which can block the flow of water leading to the river flooding the surrounding land. 4\. Water pollution -- Mining often leads to a serious form of water pollution known as acid mine drainage. Water accumulating in abandoned mines reacts with sulfur containing minerals that result in sulfuric acid being formed. This also dissolves metallic minerals. Water seeping through mines pollutes streams and groundwater with acids and toxic metals. No description available. 5\. Air pollution -- Surface mining and quarrying operations generate a lot of dust, resulting in air pollution with particulate material. This is harmful to health and smothers the surrounding vegetation. This heavy machinery and vehicles used are also a source of air pollution. 6\. Noise pollution -- the noise pollution caused by the operation, and maintenance of the machinery and facilities associated with mining and quarrying can be significant health danger both for mine employees and for nearby residents. Noise pollution also has negative effects on wildlife. In the case of metal ores, once the ore is extracted, the metal is separated from other rock material. For many this is done by smelting. **Smelting**: releasing the molten metal from the ore by strongly heating the one with other substances such as carbon and limestone. Smelting is an energy intensive process that typically depends on coal and other fossil fuels. Smelting plants can cause air pollution by releasing particulates (including heavy metal particles) and acidic gasses such as SO2. Modern smelting plants mitigate these issues by relying on various pollution abatement technologies. **Soil** Soil is a natural resource that supports terrestrial ecosystems and agricultural productivity. It is an abiotic resource that is formed very slowly by the weathering and erosion of rock. Soil is a complex mixture of weathered rock particles, mineral nutrients, decaying organic matter (detritus), water, air and living organisms interacting together. A soil is not a uniform material and soil structure changes with depth. In deep soils several distinct layers or soil horizons may be observed. Five main soil horizons may be observed. Five main soil horizons are generally recognised: - O horizon (humus/organic matter) - A horizon (topsoil -- this is the most fertile soil layer) - B horizon (subsoil) - C horizon (parent material -- weathered bedrock) - R horizon (bedrock) 1. Minerals and mineral holding capacity -- Plants require various mineral nutrients, particularly nitrates, phosphates and potassium. These are produced by the decay of organic matter. A lack of humus (dead organic matter) results in a low mineral content. A soil's mineral holding capacity is also important. If minerals are easily lost by leaching, the soil will lose fertility. 2. Water and water holding capacity -- soils lacking water cannot be fertile since most plants will not survive long without water. The amount of water present depends on the climate but also on soil texture. This depends upon the size of the particles that make up the soil. 3. Aeration -- Plants roots need air. If a soil lacks air spaces or all air spaces are filled with water (a waterlogged soil) the roots will rot, and plants will not survive. 4. Soil pH -- Most plants grow best between pH 6.5 and 7.2. A soil that is too acidic or too alkaline causes mineral nutrients unavailable to plants. Lime can be added to decrease acidity, while alkaline soils benefit from the addition of humus.  5. Salinity -- This is the salt content of soil. Salts are naturally found in soils due to weathering. However, certain climatic conditions and inappropriate farming techniques lead to an increase in salinity (salinization). High salinity inhibits plant growth by reducing water uptake and affecting beneficial soil microbes. Soil texture Soil texture depends very much on the size of the mineral components (particles) that make up the soil. Depending on their size, soil particles are referred to as: - Clay particles (very fine) - Silt particles (fine) - Sand particles (medium sized particles) Definitions related to water and soil - Permeability -- the ability of water to flow through the soil - Infiltration -- the process by which water on the surface enters the soil - Percolation -- the movement of water through the soil layers - Leaching -- the loss of water-soluble substance (nutrients) from the soil. The overall texture of a soil depends very much on the relative amounts of different sized particles. - Clay soils have a high proportion of fine clay particles - Sandy soils have a high proportion of sand particles - Loam soil have a more even mixture of particles of different sizes (sand, silt, and clay particles) i. Overgrazing ii. Deforestation iii. Over-cultivation iv. Off roading i. Gullying ii. Silting of water bodies iii. Loss of topsoil and decreased soil fertility Soil erosion leads to poor soil structures with poor drainage can become waterlogged (saturated with water). As water fills all the air spaces plant roots die. Waterlogging can lead to salinization with soil becomes more saline over time. When waterlogging takes place, rather than percolating through the soil, water accumulates at the soil surface. This then evaporates, leaving behind dissolved salts in the top layers of the soil. Waterlogging and salinization reduce agricultural yields and leave exposed soils that become more prone to further erosion. iv. Climate change v. Desertification Reducing soil erosion Good farming practices can minimize soil erosion. Such practices include: i. Contour farming: Planting crops in rows around a hill rather than up and down the hill. Contour farming creates hundreds of small ridges or dams that slow down water flow and increase infiltration, hence reducing erosion. Contour farming increases the amount of water percolating through the soil, promoting crop yields and helping recharge aquifers. ii. Terracing This involves shaping the land to create level steps (terraces) that retain soil and water. Locally, rubble walls are used to prevent the loss of soil from terraced fields. Terracing makes it possible to farm quite steep hills. Rubble walls are also the habitat of many different animal species. iii. Windbreaks iv. Multi-cropping (polyculture) v. Alternation of land use vi. Reduced tillage (reduced ploughing) Chemical fertilisers Natural fertilisers ------------------------------------------------------------------------------------------ ------------------------------------------------------------ Deliver an exact amount of nutrients -- you know exactly the amount of nutrients present Tend to be more variable in nutrient content Convenient to use May be less convenient to use and store They are likely to cause more air and water pollution Less likely to be major sources of air and water pollution i. **Clearing of forests (deforestation) and natural habitats to make way for agriculture.** ii. **Use of Pesticides** iii. **Monocropping (monoculture)** i. Livestock rearing contributes to air pollution. Ruminants (typically cows, goats and sheep) releases methane to the atmosphere as part of their digestive process. Decomposing manure also releases methane. Rice paddy fields also release a lot of methane. Methane is a greenhouse gas and is a driver of global warming. ii. Fertilizers supply nitrogen to the soil in the form of ammonium ions and nitrates. Nitrates are broken down by soil bacteria (denitrifying bacteria) into nitrogen and nitrous oxide. Nitrous oxide is both a greenhouse gas (contributes to global warming) and an ozone depleting substance. No description available. iii. Soil erosion and the burning of crop residues release particulate matter into the air. **Agriculture and water quality** Agriculture is a major driver of water pollution. i. Agriculture and eutrophication Eutrophication = an increase in nutrient levels in the water 1\. Fertilisers + Animal Waste Production and plant nutrients like nitrates and phosphates end up in the water body due to Leaching and Surface Runoff 2\. These nutrients cause Eutrophication, creating an increase in the nutrient levels in the water. 3\. This increase of nutrients that grow plants causes an Algal boom 4\. Algae are short lived and die so organisms who died become decomposed by bacteria. 5\. By decomposition, the Oxygen is used up, leaving water with very low Oxygen Levels. 6\. This low oxygen level causes ecosystem disruption as there won't be enough oxygen for other organisms IMP - Eutrophication ii\. Agriculture and groundwater pollution with nitrates Nitrates can leach into groundwater -- hence high nitrate levels of Maltese aquifers. iii\. Agriculture and water pollution with pesticides Pesticides are carried by wind and rainwater runoff into water bodies such as rivers and reservoirs, killing aquatic life and affecting biodiversity and ecosystems. iv\. Agriculture and silting of water bodies Soil carried away by rain can be deposited in lakes and reservoirs, silting water bodies. This affects aquatic ecosystems and can also lead to flooding by blocking the flow of water. **Agriculture and Genetically Modified Organisms (GMOs)** Genetically Modified Organisms (GMOs) = animal, plant or microbes whose genetic material (DNA) has been altered using genetic engineering techniques to have certain desired traits i. Heavy machinery tramples over saplings affecting forest regeneration. ii. Loss of habitat and biodiversity -- some species are endangered due to overharvesting (e.g. Brazilian mahogany which is now protected but still logged illegally) iii. Soil compaction and erosion leading to silting of watercourses Most unsustainable and illegal logging takes places in tropical forests with a huge loss of biodiversity. In poor countries, the lack of development opportunities makes unsustainable logging difficult to control. In much of Europe and North America, forestry is more sustainable involving planned harvests, replacement of harvested trees and areas of mixed forest to support biodiversity. **Hunting and Fishing** Many wild animals, common and rare, are killed for food, mainly in the less developed regions of Africa, Asia and South America. This practice is often unsustainable but overharvesting of wild animals is difficult to regulate since it is often driven by poverty. Animals are also killed for other purposes such as ivory, fur, hides etc. The largely illegal trade in wild-caught exotic species is also seriously endangering rare species. Even in North America and Europe, various species are regularly hunted for sport and food. In many cases recreational hunting is well-regulated and does not threaten wild populations. However, illegal hunting can be problematic. Many whale species have been hunted almost to extinction for their meat and blubber. A ban on commercial whaling, upheld by most countries, has led to the recovery of most species. Overfishing has depleted many fisheries. Most commercially important species are being over-harvested to their sustainable maximum e.g. the bluefin tuna in the Mediterranean and the North Atlantic cod. Apart from affecting the species being overharvested, overfishing can also disrupt marine ecosystems by interfering with predator-prey interactions. Unsustainable fishing is due to various reasons: i. Increased demand ii. Destructive fishing methods (e.g. trawling) iii. By-catches of juvenile and undersized fish iv. Large fishing fleets v. Large boats with fish catching technology vi. Illegal fishing vii. Fishing agreements that allow foreign fleets to over-fish the seas of developing nations. Urgent action is needed for the better management of many biotic resources. Sustainable management of resource can involve: i. Quotas -- these set limits on the harvesting of certain species -- ex: the bluefin tuna in the Mediterranean ii. Protected habitats -- terrestrial and marine protected areas are set aside to protect species from over-exploitation. They can be important as breeding grounds for the species concerned. iii. Monitoring and enforcement -- monitoring the populations of certain species and strict enforcement of legislation (quotas/hunting seasons/ minimum size of fish that can be sold etc.) can help manage biotic resources more sustainably. iv. Afforestation and restoration of degraded habitats -- Afforestation and restoration projects can create or recover habitats that support a variety of biotic resources. v. Aquaculture -- increased reliance on aquaculture reduces pressure on wild stocks of the species concerned, even though aquaculture itself needs proper management to minimize any negative impacts on the environment. Aquaculture: is the science and practice of breeding, growing, and harvesting fish, shellfish and aquatic plants. It is essentially farming in water. vi. Resource substitution -- this involves substituting a threatened resource with one which is less threatened. This includes initiatives promoting the increased consumption of commoner fish such as mackerel and reducing the consumption of rarer fish. \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--TILL THIS LINE FOR TEST\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-- Earth and Management of its resources **Energy sources** **Energy is the ability to do work.** The unit of energy is the Joule Energy sources are either renewable or non-renewable. Non-renewable energy sources are finite sources that do not replenish themselves, at least on human timescales, and are depleted by consumption. They include fossil fuels (coal, petroleum and natural gas) as well as uranium. Renewable energy sources are non-finite sources that continue to exist despite being consumed or replenish themselves as they are used. They include things like the sun, wind, water, geothermal, and biomass. The energy sources used will determine the carbon footprint. The carbon footprint is the total amount of greenhouse gases released to the atmosphere through anthropogenic activity. ANTHROPOGENIC -- OF HUMAN ORIGIN Anthropos (humankind) and genesis (origin) The water and electricity bills reflect the carbon footprint. Higher bills indicate a higher carbon footprint. The kilowatt-hour (kWh) is the unit of energy used to measure electrical consumption. One kilowatt-hour (kWh) is equivalent to 3,600,000 Joules. (1kWh is 1000 Watts for 1hr) The EU energy label is a means of quantifying the energy efficiency of appliances and electrical goods. The EU energy label helps consumers choose more energy efficient appliances. The energy efficiency of the appliance is rated in terms of a set of energy efficiency classes from A to G on the label, A being the most energy efficient, G the least energy efficient. Even though carbon emissions from the burning of fossil fuels is the main driver of global warming, more than 80% of the world's commercial energy still comes from fossil fuels. Decarbonisation is necessary to reduce the impacts of climate change. Decarbonisation is the removal or reduction of carbon dioxide outputs into the atmosphere. Decarbonisation is achieved by switching to usage of low carbon energy sources. Decarbonisation requires generating energy from a varied mix of sources, increasing the proportion of clean energy while gradually reducing the dependence on fossil fuels. Non-renewable sources of energy Despite not being sustainable (they are finite), non-renewable sources still supply most of the global commercial energy demands. Non-renewable energy sources include fossil fuels and nuclear fuels. 1. Fossil fuels Over 80% of the energy generated for electricity, industry and transport still comes from the combustion of fossil fuels. Fossil fuels were formed from the decomposition of the remains of dead organisms with Earth's crust. The main fossil fuels are petroleum (crude oil), natural gas, and coal. In oil refinery, different products (petrol, diesel, kerosene, light and heavy fuel oils, grease, asphalt) are produced from crude oil.  Hydrocarbon: Substance / compounds that are made up of Carbon and Hydrogen only Advantages of fossil fuels \- A relatively high net energy yield \- A well-developed technology for their extraction and use \- Unlike some renewables, they are forms of potential energy and are easily transported from one region/country to another using tankers/pipelines/ships and trains (coal) and can be used everywhere.