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SYSTEMS OF THE EARTH Dr. Jānis Zaļoksnis 1 Parana river (near the Iguasu waterfall) - boarder between Brasil un Paraguay Dump of cars, USA 3 HUMANS AND THE ENVIRONMENT An aggregate of interconnected elements that performs specific functions is called a system (from the Greek word systema, which means ‘a whole consisting of parts’). System theory classifies systems by their level of complexity. The natural systems comprising the Earth and everything on it are extremely complicated systems. The Earth functions by means of specific systems (spheres) – the atmosphere, hydrosphere and lithosphere – and the flows of substances and energy among these systems. 4 5 Systems Systems can be open, closed or isolated. In an open system, the flows of substances and energy are not restrict. The interaction can take the form of information too. As the environment influence the system, the system also influence environment. Isolated system exchanges neither energy, matter, nor information with its environment. In physics a closed system is permeable to energy but not to matter (smelted test-tube). A closed system is more resistant for incorporating new information. The concept was expanded upon with the information theory and subsequently systems theory. Today the concept has its applications in the natural and social sciences. 6 Earth systems Atmosphere 5,2 × 1018 Turnover period, years 0,2 Hydrosphere 1,4 × 1021 1600 Biosphere 4,2 × 1015 60 Crust 2,4 × 1022 >3 × 107 Mantle 4,0 × 1024 >108 silicates, carbonates, sulphides, oxides silicates (olivine, pyroxene) Core 1,9 × 1024 permanent iron and nickel Mass, kg Chemical elements N2, O2, H2O, CO2, Ar H2O (water, ice), dissolved substances in water (Na+, Ca+2, Cl-) organic substances , H2O Aggregative state gaseous liquid, solid liquid, solid Lithosphere: solid solid fluid (inner core – solid) 7 Earth systems The Earth, on the one hand, can be considered a closed system with respect to the flows of substances (the Earth’s mass is increased by a relatively small mass of falling meteorites, and a relatively small mass of substances leaves the upper layers of the atmosphere and dissipates into outer space). On the other hand, it is an open system with respect to the fluxes of energy (the Earth receives energy from the Sun and reflects part of the received energy into outer space). A characteristic feature of systems is their capability to react on various influences – feedback, which can be positive or negative. This feedback or counteraction is auto-regulative – it stabilises the system, maintains it in a relatively constant state. The feedback is positive when an impact on the system results in a further magnification of the system’s activity. 8 Watt’s Regulator A typical example of negative feedback in an inanimate, technical system is Watt’s Regulator. When the fly-ball rod rotation speed increases, the centrifugal force makes the system close the steam valve to the cylinder, thus ensuring that the engine always runs at the same speed. 9 Mechanism of feedback POPULATION;; INDUSTRIAL CAPITAL POPULATION 10 ATMOSPHERE Jupiter ATMOSPHERE The atmosphere is composed of gaseous substances (O2, N2), the hydrosphere consists of water and substances dissolved in it, whereas the structure of the lithosphere, which makes a large part of the Earth’s mass, is clearly heterogeneous. The total mass of the atmosphere is 5.2 × 1018 kilograms or approximately one millionth of the Earth’s mass, and it is relatively small compared to the masses of the hydrosphere and lithosphere. The atmosphere plays a vital role in climate control, preventing the Earth from becoming too hot or too cold. The atmosphere diffuses the energy from the Sun, thus maintaining the temperature balance and climate life-friendly. Water vapour and carbon dioxide in the atmosphere reflects part of the heat radiating from the Earth’s surface, helping to keep up temperature on the Earth considerably higher. The atmospheric gases are involved in an active substance exchange with lithosphere, biosphere and hydrosphere, taking active part in all kinds of migration processes of substances and elements. 12 Variability of the Earth’s atmosphere and temperature depending on the distance from the Earth’s surface 13 ATMOSPHERE The atmosphere’s high mobility supports transport of airborne pollutants from one area of the Earth to other regions and even their dispersion on a global scale. A large part of the processes taking place in the biosphere depend on the composition of the air that is used for maintaining life processes, especially in the case of organisms which are much more complicated. Even microscopic amounts of toxic substances can cause adverse effects on human health if exposure takes place for longer periods of time. Earth’s surface, while short-wavelength radiation (ultraviolet light, X-rays, γ rays) is absorbed in the upper layers of the atmosphere. 14 HYDROSPHERE The hydrosphere is the sum of all water on the Earth’s surface and in the Earth’s crust near the surface. The World Ocean makes the largest part of it. The presence of water is a precondition for life on the Earth, and the existing forms of living organisms are to a great extent determined by water. Water is the main substance forming living organisms. Water is not only the main component of the hydrosphere; it also significantly affects the processes in the biosphere, atmosphere and – being a critical factor for many geological processes – the lithosphere. 15 16 HYDROSPHERE The mass of the hydrosphere is 1.5 × 1018 tons, and its total area (ocean + glaciers and ice caps + lakes + rivers + swamps + wetlands) is 383 million km2 , which is 75 % of the total area of the Earth’s surface (510 million km2 ). 17 LITHOSPHERE The hard and rigid outer layer of the Earth – the lithosphere – is up to 200 km deep, and it comprises the Earth’s crust and the outer part of the upper mantle. The lithosphere is underlain by the asthenosphere and the deeper part of the upper mantle made of partly melted flowing rock and magma that can come to the Earth’s surface during volcanic eruptions. The Earth’s outer core is liquid, and it makes ~30% from the Earth’s mass, whereas the inner core is solid and composed mostly of iron and nickel. 18 LITHOSPHERE Inner structure of the Earth 19 FOUR SPHERES 20 Biological diversity 21 BIOSPHERE Biosphere is simultaneously both the entirety of all living beings (biomass) and their habitat environment. Biosphere is the space inhabited by living organisms in different concentrations. There are only a few bacteria per cubic meter in the upper layers of the atmosphere. In the tropical rainforests of the equatorial zone is not only high biological diversity but also a huge number of individuals within a specific unit area. Biosphere is an extremely complicated and dynamic system which is affected by a multitude of different external factors, including contingent ones, such as the tectonic processes in the Earth’s crust, ice covers, natural disasters etc. The total number of known species of animals and plants reaches almost 3 million; from these, almost 300 000 are autotrophy, i.e. organisms producing the primary biomass. 22 BIOSPHERE The total estimated global mass of living biological organisms is the biomass, and it ranges from 2.4 × 1012 tons to 1 × 1013 tons of dry matter, the largest part of which is phytomass (phytoplankton, trees, grasses), whereas the amount of zoomass is estimated from 2 to 10 % of the total biomass. The total of approximately 2.3 × 1011 tons of biomass is produced annually. Biomass constitutes 0.01 % of the mass of the Earth’s crust, and it would make a 2 cm layer if it were evenly dispersed over the Earth’s surface. The largest amounts of biomass are concentrated in tropical rainforests – 65 kg/m3 on average, whereas in boreal forests (taigas) it is 20–25 kg/m3, in fertile zone steppes – 1 kg/m3, in deserts – 0.25 kg/m3. The concentration of biomass in the World Ocean at large is close to that of deserts, while in some places it is comparable to steppes and savannas. 23 Rotor stump remover recover a tree roots for a biomass Sugarcane plantation in Brazil (State of São Paulo), cane remains used to production of biomass energy. A cogeneration plant in Metz, France. The station uses waste wood biomass as energy source, and provides electricity and heat for 30,000 dwellings. Eucalyptus in Brazil, remains of the tree are reused for biomass power generation. Barley: grains – 1.6–2.8 tons/acre, straw – 0.9–2.5 tons/acre, total – 2.5–5.3 tons/acre Corn: grains – 3.2–4.9 tons/acre, stalks and stovers – 2.3–3.4 tons/acre, total – 5.5–8.3 tons/acre Oat: grains – 1.4–5.4 tons/acre, straw – 1.9–3.2 tons/acre, total – 3.3–8.6 tons/acre Rye: grains – 2.1–2.4 tons/acre, straw – 2.4–3.4 tons/acre, total – 4.5–5.8 tons/acre Wheat: grains – 1.2–4.1 tons/acre, straw – 1.6–3.8 tons/acre, total – 2.8–7.9 tons/acre One international acre is defined as exactly 24 4046.8564224 square metres. BIOSPHERE The main categories of living systems are cell, organism, population and species community. Cells and organisms actively react on environmental changes, grow, develop and reproduce. The cell is the basic structural element of organisms, the organisms of one species make a population, while the species that are interrelated or have similar demands from the environment constitute communities of species. A species community and its non-living environment inhabited, make a system of a higher category – an ecosystem. Each species is unique, and it has specific and distinctive functions in the ecosystem. All species of organisms living on the Earth can be classified into four kingdoms: bacteria, fungi, plants and animals (viruses are not included in this classification). 25 ECOSYSTEM The living components of an ecosystem are made up of the organisms of different species that populate the same habitat, usually interact and make a food chain. The whole of species within an ecosystem is called a species community. The whole of all components of non-living nature (rocks, water, air) that host a species community is called a biotope. 26 ECOSYSTEM Hierarchy of ecosystems Ecosystems can be of different sizes, from microecosystems, such as a rotting stump, to mesoecosystems and macroecosystems, such as a forest, a lake, the island of Madagascar or the Pacific Ocean. All the ecosystems of the planet constitute the megaecosystem – biosphere. Ecosystems are open systems, which means that they continuously receive and emit energy and different substances. 27 ECOSYSTEM Boundary between the forest and meadow ecosystems makes a forest edge ecotone – brushwood, which contains both forest and meadow species The main function of an ecosystem is to maintain life continually, synthesising organic substances with complex molecular structure – such as cellulose, sugars, proteins and fats – from elementary inorganic substances, such as gases, water, salts etc. When organisms die off , they decompose back into elementary substances. Ecosystems cannot be described in spatial terms only, because there are no exact boundaries between them – unless nature itself has demarcated such boundaries, for example, the line between dry land and water. Usually the transition from one ecosystem to another is gradual, and the transition area is called an ecotone. 28 Moos is the symbiosis of the algae and fungi. 29 ECOLOGICAL FOOD CHAIN The ecological food chain represents the feeding hierarchy of organisms in an ecosystem as well as the flow of substances and energy in it. The ecological food chain ordinarily consists of three to four trophic levels. 30 Ecological pyramid of numbers Energy deficit and losses in the trophic food chain causes the situation when usually within an ecosystem there are more plants than herbivores and more pray than predators. 31 Ecological food web Species that act at different levels of the food chain make the nodes of the food web, whereas species that consume just one type of food are linked to the web with a single link. 32 Ecological succession in terrestrial ecosystems A field becomes overgrown and transforms into a spruce forest within a period of approximately 80–100 years. Several stages can be distinguished in this process. During each stage, there is a distinctive biological community with a specific composition of plant and animal species. 33 Humans in ecosystem Humans also are part of an ecosystem – one of the species of living organisms. However, humans surpass any other organisms in their ability to influence ecosystems most, to use the biological production of these ecosystems, to change the composition of species as they consider necessary. To manage the ecosystems successfully, a good knowledge of their functioning, the organisation of species within them etc. are required. With their actions, humans are capable of sustaining or destroying the ecosystems of the planet. Since the destruction of the biosphere would bring the very existence of human beings to an end, humans should be objectively concerned with sustainable development of ecosystems. 34 Rock cycle Some minerals are enduring and stable, and they have remained intact throughout the environment, pressure and temperature changes. Others, in contrast, are dynamic, have repeatedly changed their mineral form and play an active role in the transformations of the composition and properties of the Earth’s crust. This process is called the rock cycle, and for stable minerals it can last for billions of years. 35 ENERGY CYCLING AND THE EARTH’S CLIMATE The main source of energy on the Earth is the Sun. The key factors that determine the extent to which the Sun’s energy reaches the Earth are the following: - distance covered by radiation; - angle at which solar radiation reaches the Earth’s surface; - composition of the atmosphere; - the interaction of solar and cosmic radiation with gases forming the Earth’s atmosphere. 36 Natural waters on the Earth Natural waters are categorised according to their overall level of mineralization (the proportion of mineral substances dissolved in water). The main types of water are the following: freshwater (its overall concentration of salts is up to 1 g/l), brackish water (1– 10 g/l), saline water (10–35 g/l) and brine (35 g/l and more). Freshwater makes just a small part of all the water on the Earth – approximately 3 %. 37 Natural waters on the Earth 38 Water resources Water are consumed daily in order to satisfy all the needs of each person, including the production of food and commodities and provision of services. Due to the relatively high precipitation and low evaporation rates, there are sufficient freshwater supplies for people and economies in the Baltic Sea Region. At present, the amount of water that humans consume is comparable to a substantial part of the runoff of the world’s rivers. However, the consumption is expected to exceed the resources of natural water flows in the near future. 39 Aral Sea in 2008. The black line shows the area of the Aral Sea in 1960. 40 CARBON CYCLE Carbon is the most important element for living organisms. With the average concentration of 350 mg/kg, carbon is not so pervading on the Earth, but it has an exceptional role in the cycling of elements. In the carbon cycle (biogeochemical cycle), one carbon compound is converted into others, and this process occurs in the atmosphere, hydrosphere, lithosphere and biosphere. In the lithosphere, carbon is stored in carbonate sedimentary rocks (limestone – CaCO3, dolomite – CaMg(CO3)2 and others), and it also forms fossil fuel sediments (coal, oil, bituminous shale). Large amounts of carbon compounds (carbon dioxide and methane) are stored in the permafrost zone, and they also form water body sediments and the decomposition products of organic substances in the soil. In the hydrosphere, carbon compounds are present in living organic matter, carbonate ions and hydrogen carbonate ions in the form of dissolved carbon dioxide and methane. The atmosphere contains approximately 760 billion tons of carbon in the form of such compounds as carbon (II) oxide (CO), carbon (IV) oxide (CO2) and methane (CH4). Carbon compounds have different cycling periods at each stage of the cycle: in the atmosphere it is quite short – 3 years, in the soil – 25 years, in the oceans – 350 years, while the cycling period of carbonate rocks is more than hundreds of millions of years. 41 CARBON CYCLE Amounts stated in PgC, fluxes – in PgC/y. 42 METRIC PREFIXES Prefix Symbol 1000m 10n Decimal English word short scale long scale Since yotta Y 10008 1024 1000000000000000000000000 septillion zetta Z 10007 1021 1000000000000000000000 sextillion exa peta tera giga mega kilo hecto deca E P T G M k h da deci centi milli micro nano pico femto atto d c m µ n p f a 10006 10005 10004 10003 10002 10001 10002/3 10001/3 10000 1000−1/3 1000−2/3 1000−1 1000−2 1000−3 1000−4 1000−5 1000−6 1018 1015 1012 109 106 103 102 101 100 10−1 10−2 10−3 10−6 10−9 10−12 10−15 10−18 0.1 0.01 0.001 0.000001 0.000000001 0.000000000001 0.000000000000001 0.000000000000000001 quintillion trillion quadrillion thousand billion trillion billion billion thousand million million thousand hundred ten one tenth hundredth thousandth millionth billionth thousand millionth trillionth billionth quadrillionth thousand billionth quintillionth trillionth zepto z 1000−7 10−21 0.000000000000000000001 sextillionth thousand trillionth 1991 yocto y 1000−8 10−24 0.000000000000000000000001 septillionth quadrillionth 1000000000000000000 1000000000000000 1000000000000 1000000000 1000000 1000 100 10 1 quadrillion 1991 thousand trillion 1991 1975 1975 1960 1960 1960 1795 1795 1795 – 1795 1795 1795 1960 1960 1960 1964 1964 1991 43 NITROGEN BIOGEOCHEMICAL CYCLE Nitrogen makes 76% of the atmosphere’s mass, and it is one of the most important chemical elements in proteins and DNA; therefore, it is one of the elements necessary for the existence of living organisms. At the same time, the concentration of nitrogen compounds in the lithosphere and hydrosphere is quite low. Unlike oxygen, nitrogen is inert, and most living organisms cannot utilise it directly, because the bonds between atoms in nitrogen molecules are very stable. Processes in the nitrogen cycle ensure the bonding of atmospheric nitrogen (N2) into such compounds that can be utilised by living organisms. In the environment nitrogen compounds are found as nitrogen (I) oxide (N2O), nitrogen (II) oxide (NO), nitrogen (IV) oxide (NO3), nitric acid (HNO3), ammonia (NH3) and ammonium salts. Other nitrogen compounds either form intermediate products in various reactions, or are unstable and decompose fast. 44 NITROGEN BIOGEOCHEMICAL CYCLE 45 NITROGEN BIOGEOCHEMICAL CYCLE 46 USE OF THE NITROGEN COMPOUNDS Nitrogen fixation amounts in nature and by human activity on a global scale 47 NITROGEN ON THE EARTH Nitrogen compounds are among the basic nutrients needed for plant growth, and they are used in agriculture for soil fertilisation in order to promote the growth and yield capacity of cultivable plants. Unfortunately, a significant part of the nitrogen compounds used for fertilisation leaches into surface waters and groundwaters and, along with surface runoff – further into the seas and oceans. Nitrogen compounds also fall out with atmospheric precipitation. In effect, both water and soil become oversaturated, causing eutrophication. In present-day Europe, the emission of nitrogen compounds has become one of the most hazardous environmental pollution factors. It is an urgent problem for the Baltic Sea Region countries, where the concentration of nitrogen compounds incites many harmful processes, including the pollution in the Baltic Sea. Nitrogen compound fallout with atmospheric precipitation – changes in the amounts during the last centuries and a forecast 48 PHOSPHORUS BIOGEOCHEMICAL CYCLE The phosphorus cycle differs from the cycles of other elements by the fact that it does not contain substances in gas phase for the reason that most phosphate compounds are non-volatile or solid. The amount of phosphorus compounds in the atmosphere is small, and they are usually extracted from the lithosphere’s sedimentary rocks in the form of various apatites (mostly calcium phosphates) that have formed in shallow seas tens of millions years ago. Phosphorus compounds are predominantly (~90%) used as inorganic fertilisers in agriculture. The estimated global utilisation of fertilisers is 15 million tons per year. The second major area of phosphorus compound utilisation is in detergents. Phosphorus compounds intensifying the processes of eutrophication in waterbodies. 49 PHOSPHORUS BIOGEOCHEMICAL CYCLE 50 Men and environment – systemic approach 51 52 Critical attitude needed 53 Critical attitude needed 54 Thanks for attention ! 55