ECOSYSTEMS AND ENVIRONMENTAL HAZARDS.pptx

ECOSYSTEM AND ENVIRONMENTAL HAZARDS 1.

[Audio] An ecosystem is a community of different species interacting with one another and with their non-living environment, exchanging energy and matter. Ecosystems were first proposed by A G Tansley in 1935. They are the foundation of the biosphere and determine the health of the entire earth system..

[Audio] There are two main types of ecosystems: natural and artificial. Natural ecosystems include terrestrial and aquatic ecosystems. Terrestrial ecosystems can be further divided into grasslands, forests, oceans, and ponds. Aquatic ecosystems also have various subtypes such as oceans and ponds..

[Audio] The abiotic component of an ecosystem includes factors such as sunlight, precipitation, humidity, wind, water cycle, carbon cycle, nitrogen cycle, lipids, carbohydrates, proteins, and inorganic substances. These are all non-living elements that affect the functioning of the ecosystem. The biotic component consists of living organisms such as plants, animals, microorganisms, and decomposers that interact with each other and their environment to maintain the balance of the ecosystem..

[Audio] Biotic components interact with each other and their environment in an ecosystem. They can be categorized into three main groups: producers, consumers, and decomposers. Producers are organisms that produce their own food through photosynthesis, such as plants. Consumers are organisms that obtain their energy by consuming other organisms, including herbivores, omnivores, and carnivores. Decomposers are organisms that break down dead or decaying organic matter, such as fungi and bacteria. Interactions between these components play a crucial role in maintaining the balance and diversity of an ecosystem..

[Audio] The ecosystem consists of both living and non-living elements. These two types of components interact with each other in various ways. The presence of one component can have a positive effect on another, while its absence may lead to negative effects. For example, if there is no sunlight, plants will not undergo photosynthesis, which affects herbivores that feed on them, carnivores that prey on those herbivores, and so on. Similarly, the removal of any abiotic factor such as water or soil would disrupt the entire food chain. This demonstrates the interconnectedness of an ecosystem, where every element plays a vital role..

[Audio] Carbon plays a crucial role in sustaining life on Earth through its continuous cycle between living organisms and the atmosphere. This process involves two key mechanisms: photosynthesis and cellular respiration. During photosynthesis, carbon dioxide (CO2) from the atmosphere is absorbed by plants, algae, and some bacteria, using sunlight as energy. They convert this CO2 into glucose (C6H12O6), releasing oxygen (O2) in the process. On the other hand, cellular respiration occurs within these same organisms, where they break down glucose to release energy, producing carbon dioxide and water as byproducts. This constant exchange of carbon between the atmosphere and living organisms maintains the delicate balance necessary for life to thrive..

[Audio] An ecosystem comprises living organisms such as plants, animals and microorganisms interacting with each other and their physical environment. This interaction occurs within a specific area or habitat. The components of an ecosystem comprise biotic factors like producers, consumers and decomposers, and abiotic factors like water, soil and sunlight. These components interact and affect one another in complex ways, resulting in a dynamic balance within the ecosystem..

[Audio] Nitrogen makes up about 78% of the atmosphere's volume and is essential for life on Earth. However, this nitrogen gas cannot be used directly by living organisms; instead, it must be converted into a usable form through a process called nitrogen fixation. Nitrogen fixation involves converting atmospheric nitrogen into a more accessible state, such as ammonia or nitrate, allowing plants to absorb it through their roots. The steps involved in the nitrogen cycle are nitrogen fixation, assimilation, ammonification, nitrification, and denitrification. Nitrogen fixation is mainly performed by free-living or symbiotic bacteria, while some fixation also occurs naturally through lightning strikes. After being fixed, nitrogen is absorbed by plants in the form of nitrate ions or ammonium ions, which they use to build proteins, nucleic acids, and other vital compounds..

[Audio] The process of ammonification or mineralization occurs when a plant or animal dies, or an animal expels waste. Bacteria or fungi convert the organic nitrogen into ammonium (NH4+). Soil-living bacteria and other nitrifying bacteria primarily carry out the conversion of ammonium to nitrate. They oxidize the ammonium (NH4+) to nitrite, which is then further oxidized to nitrate by Nitrobacter. Nitrates are reduced back into the largely inert nitrogen gas (N2) through the action of certain bacterial species, such as Pseudomonas and Clostridium, under anaerobic conditions. These bacteria utilize nitrate as an electron acceptor instead of oxygen during respiration, resulting in the formation of various nitrogen compounds like nitric oxide (NO2¯), nitrous oxide (N2O), and ultimately nitrogen gas (N2)..

[Audio] Phosphorus moves in a cycle through rocks, water, soil and sediments and organisms. Rain and weathering cause rocks to release phosphate ions and other minerals over time. Inorganic phosphate is then distributed in soils and water. Plants take up inorganic phosphate from the soil. The phosphorus cycle is crucial because phosphorus is an essential nutrient for sustaining life on Earth. It plays a central role in the transfer of energy within organisms, the structure of the genetic material, and in the composition of cell membranes, bones and teeth. Weathering releases phosphorous present in rocks into the soil through the action of rain or by acid-producing bacteria. Water carries phosphorous down mountains and slopes, depositing it in oceans. Volcanic activity results in the release of phosphorous from the inside of the Earth to the soil. The phosphorous in this step is in inorganic form..

[Audio] Phosphorus present in the soil is absorbed by plants despite the limited availability of this nutrient. To meet the nutritional requirements of plants, phosphate fertilizers are applied to the soil. Herbivores ingest these plants, which are subsequently consumed by carnivores and omnivores, resulting in the transfer of phosphorus to various animals. Aquatic plants acquire the necessary phosphorus from the ocean floor, where it is deposited as sediment in the soil. Symbiotic organisms facilitate the release of oxygen from the soil to plants. In plant and animal bodies, inorganic phosphorus is converted into organic phosphorus, becoming a component of their DNA and enabling various physiological processes. Phosphorus in animals is used for the synthesis of biomolecules and bone formation..

[Audio] The decomposition process involves the breakdown of dead organisms into simpler substances by microorganisms such as bacteria and fungi. This process releases nutrients back into the ecosystem, making them available for other living things. In this context, the return of phosphorus back to the ecosystem occurs through the conversion of organic phosphorus into inorganic phosphorus by specific bacteria in the soil. This process allows phosphorus to be reused by plants and animals, maintaining the balance of nutrients within the ecosystem..

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[Audio] Sulphur is released from rocks through weathering. Contact between sulphur and air results in its conversion into sulphates. Plants and microbes absorb sulphates and convert them into organic forms. Organic sulphur is consumed by animals through their diet and thus sulphur moves within the food chain. Upon death, animals release some sulphur through decomposition, while other sulphur enters microbial tissues. Natural sources like volcanic eruptions, water evaporation, and swamp organic matter breakdown release sulphur directly into the atmosphere. This sulphur precipitates on earth with rain..

[Audio] The sulphur cycle involves several key processes. Decomposition of organic compounds begins with protein degradation, releasing amino acids containing sulphur. These amino acids are reduced to hydrogen sulphide by Desulfotomaculum bacteria. Next, hydrogen sulphide undergoes oxidation to produce elemental sulphur, initiated by certain photosynthetic bacteria from the families Chlorobiaceae and Chromatiaceae. However, elemental sulphur in the soil cannot be used directly by plants; instead, it is converted into sulphates by chemolithotrophic bacteria. Finally, sulphates are reduced to hydrogen sulphide by Desulfovibrio desulfuricans, occurring in two steps: firstly, sulphates are converted to sulphites using ATP, and secondly, sulphite is reduced to hydrogen sulphide..

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[Audio] The nitrogen cycle is a vital process that occurs within ecosystems, where nitrogen is converted between its various forms. This process involves the transformation of nitrogen from its gaseous state as nitrogen gas, through the atmosphere, into compounds such as ammonia, nitrites, and nitrates. These compounds can then be used by plants and other organisms for growth and development. The nitrogen cycle is essential for life on Earth, as it provides the necessary nutrients for plant growth and supports the food chain..

[Audio] Organic substances are formed by biotic components and are linked with biotic components. They have a strong influence on the structure, behavior, and interactions of various organisms within an ecosystem..

[Audio] The biotic components of an ecosystem comprise all living organisms such as plants, animals, fungi, and microorganisms. They interact with each other and their physical environment to form complex relationships that sustain life. In this ecosystem, we find producers like plants and algae that convert sunlight into energy through photosynthesis, supporting the food chain by providing organic matter. Consumers, including herbivores and carnivores, feed on these producers and other consumers, playing crucial roles in maintaining ecological balance. Decomposers like bacteria and fungi break down dead organic matter, recycling nutrients back into the system. This intricate web of interactions ensures the continued functioning of the ecosystem..

[Audio] An ecosystem has three main functions. The primary function involves the production of starch through photosynthesis. The secondary function entails the distribution of energy in the form of food to all consumers. The tertiary function includes the decomposition of dead organisms to initiate nutrient cycling. Studying concepts like energy and material flow, food chains, food webs, and food pyramids helps understand this process. Considering factors such as productivity, decomposition, energy flow, and nutrient cycling reveals how the ecosystem's components work together as a unit..

[Audio] The rate of biomass production is referred to as productivity. The rate of production of organic matter during photosynthesis is known as gross primary productivity, which can be calculated as the total energy fixed. Net primary productivity is obtained by subtracting respiration from gross primary productivity. The rate of formation of new organic matter by consumers is called secondary productivity..

[Audio] The process of decomposition breaks down complex organic matter into inorganic substances like carbon dioxide, water and nutrients. Catalysis, leaching, humification, fragmentation and mineralization are steps involved in this process. Decomposing dead plant and animal remains in a terrestrial ecosystem results in their breakdown into simpler forms that can be reused by living organisms..

[Audio] Energy flows unidirectionally through an ecosystem. Some energy is lost due to the second law of thermodynamics. In an ecosystem, there's a sequence of eating and being eaten, known as a food chain. A type of food chain is the grazing food chain, where we have a producer like grass, a primary consumer like a goat, and a secondary consumer like a man..

[Audio] Detritus is non-living particulate organic material including the bodies or fragments of dead organisms as well as fecal material. Decomposers are heterotrophic organisms also called saprotrophs. An example of decomposers includes fungi and bacteria..

[Audio] A food web is a complex network of relationships between different species that eat other species as their source of energy. This network is made up of many interconnected food chains. Each food chain represents a series of organisms that feed on one another, with each organism serving as both predator and prey. The food web illustrates how energy flows through an ecosystem from producers like plants and algae to consumers like herbivores and carnivores, and ultimately to decomposers like bacteria and fungi..

[Audio] Organisms in an ecosystem can be arranged in a hierarchical structure based on their feeding relationships. This hierarchy is known as the trophic level, representing the position of an organism within a community or a food chain..

[Audio] Energy flows from one trophic level to another through the process of consumption. In other words, energy moves from producers to primary consumers, then to secondary consumers, and so on. This movement of energy is known as the energy flow. The amount of energy available decreases as it passes from one trophic level to the next..

[Audio] The ecological pyramid is a graphical representation of the trophic levels in an ecosystem. It shows the relationship between the number of organisms and their biomass at different levels of the food chain. The pyramid typically has four main components: the base represents the producers such as plants and algae, the second level represents the primary consumers like herbivores, the third level represents the secondary consumers like carnivores, and the top represents the tertiary consumers like apex predators. The height of each level indicates the amount of energy available at that level. The pyramid shape illustrates how energy decreases from one level to the next, with most of the energy being stored in the producers and decreasing as it moves up the food chain. This concept helps us understand the flow of energy through ecosystems and the importance of each trophic level..

[Audio] In marine ecosystems, the pyramid of biomass is typically inverted compared to terrestrial ecosystems. This means that the biomass of fish and other aquatic organisms is greater than that of phytoplanktons, which form the base of the food web. The image shows this relationship, where the biomass of fish is much larger than that of phytoplankton..

[Audio] The pyramid of energy is always upright..

[Audio] An environmental hazard is a substance, a state or an event that has the potential to threaten the surrounding natural environment or adversely affect people's health, including pollution and natural disasters such as storms and earthquakes. Hazards can be categorized into four types: chemical, physical, biological and psychosocial. Common factors causing environmental hazards include air pollution, water pollution, soil pollution, radiation pollution and noise pollution..

[Audio] Air pollutants are substances present in the atmosphere in concentrations that disturb the natural equilibrium of the atmosphere and produce undesirable effects on humans and the environment. These pollutants can take various forms, including solid particles, liquid droplets, and gases. Particulate pollutants, which are solids or liquids smaller than 100 microns that remain suspended in the air, include examples such as dust, smoke, fog, mist, bacteria, and fumes. Air pollutants can be classified into two main categories: primary and secondary pollutants. Primary pollutants are those that are emitted directly into the environment and account for over 90 percent of global air pollution. They include carbon monoxide, nitrogen oxides, hydrocarbons, sulphur oxides, and particulates. Secondary pollutants, on the other hand, are formed through interactions between primary pollutants and the atmosphere..

[Audio] Air pollution causes approximately seven million premature deaths globally each year, according to the World Health Organization. It also contaminates soil, water, and air, affecting the environment. This can result in the loss of biodiversity and disrupt the balance of ecosystems..

[Audio] Air pollutants include sulphur dioxide, nitrogen oxides, hydrogen sulphides, carbon monoxide, ammonia, hydrogen cyanides, aldehydes, fats, arsenic, suspended particles, lead, and ozone. These substances contribute to several major environmental issues. Acid rain occurs when rainwater mixes with polluting gases like sulphur dioxide and nitrogen oxide in the atmosphere. Ozone layer depletion happens when chlorine and bromine atoms interact with ozone molecules in the stratosphere. The greenhouse effect is also a significant concern, primarily driven by water vapor, carbon dioxide, and methane emissions..

[Audio] Any change in the natural quality of water that makes it unfit for use by humans, animals, and aquatic life is referred to as water pollution. This can occur through various means, including the contamination of fresh water, marine water, and groundwater. Fresh water pollution can result from pesticides and fertilizers entering the groundwater, industrial chemicals flowing into streams and rivers, domestic sewage, thermal power plant discharges, and eutrophication caused by chemical effluent. Marine water pollution involves the release of pollutants into oceans and seas, while groundwater pollution occurs when contaminants enter underground aquifers. Water pollutants can be categorized into three main types: organic, inorganic, and biological. Organic pollutants originate from living organisms, inorganic pollutants come from non-living sources, and biological pollutants are derived from microorganisms. Large visible items polluting water are known as floatables, which encompass shipwrecks, marine debris, and trash such as paper, plastic, and food waste..

[Audio] Pesticides and fertilizers enter the groundwater, causing contamination of fresh water. Hazardous chemical pastes from industries flow into streams, rivers and ponds. Domestic sewage also flows into freshwater bodies. Thermal power plants and various industries release hot water into these bodies. This affects aquatic organisms and disrupts the aquatic ecosystem. Eutrophication occurs when chemical effluents are discharged into the water body..

[Audio] Soil pollution occurs when pollutants contaminate the soil. This can happen through various means such as industrial activities, agricultural practices, and improper waste disposal. As a result, the soil's fertility and ability to support plant growth are compromised. Additionally, soil pollution can have severe consequences on human health and the environment. For instance, exposure to certain pollutants in contaminated soil has been linked to increased risk of cancer and other diseases. Furthermore, polluted soil can lead to the contamination of groundwater, affecting the quality of drinking water. Therefore, it is essential to adopt measures that prevent soil pollution and mitigate its effects..

[Audio] Ionizing radiation refers to types of electromagnetic waves that have enough energy to remove tightly bound electrons from atoms and molecules. This process is known as ionization. As a result, these high-energy waves can penetrate tissues and deposit their energy within them. There are two main categories of ionizing radiation: electromagnetic radiation and corpuscular radiation. Electromagnetic radiation includes X-rays and gamma rays, which are forms of electromagnetic waves. Corpuscular radiation consists of alpha particles, beta particles (electrons), and protons. These particles are subatomic entities that carry energy and can cause damage to living organisms when they interact with biological tissues. Sources of radioactive pollution can be broadly classified into two groups: natural and man-made. Natural sources include cosmic rays, which originate from outside the Earth's atmosphere, and internal sources such as potassium-40 and carbon-14, which are naturally occurring isotopes found within the human body. Man-made sources encompass a wide range of activities, including medical and dental procedures involving X-rays and radioisotopes, occupational exposure in industries handling radioactive materials, nuclear reactors and radioactive fallout from nuclear accidents, environmental contamination through terrestrial and atmospheric pathways, and miscellaneous sources like TV sets, radioactive wristwatches, and isotope-tagged products..

[Audio] Nuclear explosions, radioactive wastes, and radio-isotopes are among the popular sources of radioactive pollution. They can be caused by various factors such as the production of nuclear weapons, decommissioning of nuclear weapons, mining of radioactive ore, coal ash, medical waste, and nuclear power plants. The detonation of atomic bombs over Hiroshima and Nagasaki in August 1945 led to significant effects of radiation exposure, including increased cancer rates, birth defects, and genetic mutations. Marie Curie's work with radioactive materials resulted in her death due to aplastic anemia..

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