Environmental Chemistry PDF

L1  Environmental Chemistry ❑ Environmental Chemistry is the study of chemical processes that occur in the environment and the effects of human activity on these processes. The environment refers to the natural world and the surrounding conditions in which living organisms, incl...

L1  Environmental Chemistry ❑ Environmental Chemistry is the study of chemical processes that occur in the environment and the effects of human activity on these processes. The environment refers to the natural world and the surrounding conditions in which living organisms, including humans, exist and interact. It encompasses both biotic (living) components like plants, animals, and microorganisms, and abiotic (non-living) components such as air (atmosphere), water (hydrosphere), soil (lithosphere).  Environmental Chemistry Human beings are totally dependent on the environment for life itself. Many human activities affected the environment causes pollution. Environmental Chemistry focuses on how chemicals interact with air, water, soil, and living organisms, both naturally and due to pollution or contamination.  Environmental Chemistry Environmental chemistry is vital for tackling global challenges like: Pollution. climate change. ozone depletion. resource sustainability. It provides the scientific knowledge needed to protect human health, ecosystems, and the planet while promoting cleaner, safer, and more sustainable practices.  Key Areas of Environmental Chemistry: 1.Atmospheric Chemistry: Studies chemical reactions in the Earth's atmosphere, including air pollution (e.g., smog, ozone depletion) and greenhouse gases. 2. Water Chemistry: Focuses on the chemical composition and reactions in water bodies, including oceans, rivers, lakes, and groundwater. It involves studying the impact of pollutants like heavy metals, pesticides, and nutrients (eutrophication).  Key Areas of Environmental Chemistry: 3. Soil Chemistry: Examines the chemical composition and reactions in soils. This includes the study of contaminants like heavy metals, organic pollutants, and nutrient cycling. 4. Biogeochemical Cycles: Environmental chemistry plays a crucial role in studying global cycles of elements like carbon, nitrogen, and sulfur, which are critical for life and climate regulation. 1- Atmospheric  Atmospheric Chemistry ❑ Atmospheric Chemistry is a branch of environmental chemistry that studies the chemical composition of the Earth's atmosphere, the processes and reactions that control this composition, and how human activities impact it. It is essential to understanding issues such as air pollution, climate change, and the depletion of the ozone layer.  Atmospheric Chemistry Layers of the Atmosphere: 1- Troposphere: The lowest layer (~0-12 km), where most weather phenomena and human activities occur. It contains about 75% of the atmosphere’s mass and 99% of its water vapor. The air is denser, and this is where human activities, such as aviation and pollution, mostly take place. The temperature decreases with altitude at an average rate of 6.5°C per kilometer.  Atmospheric Chemistry Layers of the Atmosphere: 2- Stratosphere: Above the troposphere (12-50 km), where the ozone layer is located, protecting Earth from harmful UV radiation. The temperature increases with altitude in this layer due to the absorption of ultraviolet (UV) radiation by the ozone layer. The stratosphere is relatively stable, with very few weather disturbances. This makes it an ideal layer for commercial jet aircraft to fly at its lower region.  Atmospheric Chemistry Layers of the Atmosphere: 3- Mesosphere: Extends from about 50 km to 85 km above the Earth. The temperature decreases with altitude, making the mesosphere the coldest layer of the atmosphere, with temperatures dropping to as low as -90°C at the top. It is the layer where most meteors burn up upon entering the Earth’s atmosphere due to increased air density. The air is too thin for commercial aircraft but too dense for satellites to orbit. (not suitable)  Atmospheric Chemistry Layers of the Atmosphere: 4- Thermosphere: Extends from about 85 km to 600-1000 km above the Earth. The temperature increases significantly, reaching as high as 2,500°C or more, due to the absorption of high-energy UV and X-ray radiation from the Sun. This layer is where the ionosphere is located, a region filled with charged particles that play a crucial role in radio communication by reflecting radio waves back to Earth. Spacecraft and satellites orbit** within this layer, as there is minimal drag due to the thin air.  Atmospheric Chemistry Layers of the Atmosphere: 5- Exosphere: Extends from about 600 km up to 10,000 km or more, blending into outer space. This is the outermost layer of the Earth’s atmosphere, where the air is extremely thin and gradually transitions into the vacuum of space. Atoms and molecules in this layer are so sparse that they rarely collide with each other, allowing them to escape into space. It consists mostly of light gases like hydrogen and helium, and the temperature can vary widely, depending on solar activity.  Atmospheric Chemistry Major Gases in the Atmosphere  Atmospheric Chemistry Major Gases in the Atmosphere 1- Nitrogen (N₂) – 78.08% (by volume), N2 is the most abundant gas in the atmosphere. It is relatively inert and does not easily react with other elements, but it plays a key role in biological processes like the nitrogen cycle, where it is converted into usable forms for plants and animals. 2- Oxygen (O₂) – 20.95%, O₂ is essential for respiration in most living organisms and is a vital component of the atmosphere. It also plays a role in combustion and is necessary for the survival of aerobic life forms.  Atmospheric Chemistry Major Gases in the Atmosphere 3- Argon (Ar) – 0.93%, Ar is a noble gas, chemically inert, and does not participate in any significant atmospheric reactions. It is the third most abundant gas in the atmosphere. 4- Carbon Dioxide (CO₂) – 0.04%, Although present in relatively small amounts, CO₂ is critical for photosynthesis and plays a significant role in regulating Earth's temperature through the greenhouse effect. Human activities such as fossil fuel combustion and deforestation have significantly increased atmospheric CO₂ concentrations, contributing to climate change.  Atmospheric Chemistry Major Gases in the Atmosphere 5- Water Vapor (H₂O) – Variable, typically 0-4%, Water vapor is a key component of the atmosphere and plays a crucial role in the water cycle, cloud formation, and weather patterns. Its concentration varies depending on temperature, location, and altitude. It is also an important greenhouse gas, contributing to the natural greenhouse effect. 6- Trace Gases in the Atmosphere: Neon (Ne) – Helium (He) – Methane (CH₄) –Krypton (Kr) – Hydrogen (H₂) – Ozone (O₃) –Nitrous Oxide (N₂O) – Chlorofluorocarbons (CFCs).  Atmospheric Chemistry Role of Atmospheric Gases: ❑ Life Support: Oxygen is crucial for respiration, and carbon dioxide is vital for photosynthesis. ❑ Climate Regulation: Greenhouse gases like CO₂, CH₄, and water vapor help maintain Earth's temperature by trapping heat. ❑ Protection from Radiation: Ozone in the stratosphere shields the planet from harmful UV radiation. ❑ Weather and Climate: Water vapor plays a key role in weather patterns and the water cycle, while gases like nitrogen and oxygen provide the stable environment necessary for life.  Atmospheric Chemistry Air pollution: ❑ Air pollution refers to the presence of harmful or excessive quantities of substances in the Earth's atmosphere, which pose risks to human health, ecosystems, and the environment. These pollutants can be in the form of gases, liquids, or solid particles, originating from both natural and human-made sources.  Atmospheric Chemistry Types of Air Pollutants: ❑ Air pollutants are generally classified into two broad categories: 1- Primary Pollutants: These are directly emitted into the atmosphere from sources such as vehicles, industrial processes, and natural events like volcanic eruptions. o Examples o Carbon monoxide (CO) o Sulfur Dioxide (SO₂) o Nitrogen Oxides (NOₓ) o Volatile Organic Compounds (VOCs) o Lead (Pb)  Atmospheric Chemistry Types of Air Pollutants: ❑ Air pollutants are generally classified into two broad categories: 2- Secondary Pollutants: These form in the atmosphere through chemical reactions between primary pollutants and other atmospheric components. o Examples o Acid rain o Particulate matter o Ground-level ozone (O₃)  Atmospheric Chemistry Types of Air Pollutants: ❑ Air pollutants are generally classified into two broad categories: 1- Primary Pollutants: These are directly emitted into the atmosphere from sources such as vehicles, industrial processes, and natural events like volcanic eruptions. o Carbon monoxide (CO) CO is a colorless, odorless gas produced by incomplete combustion of fossil fuels. It reduces the amount of oxygen that can be transported in the bloodstream, which can be harmful, especially for people with heart conditions.  Atmospheric Chemistry 1- Primary Pollutants: o Nitrogen Oxides (NOₓ) NOₓ is a group of gases, primarily nitrogen dioxide (NO₂) and nitric oxide (NO), produced during combustion (e.g., vehicle engines, power plants). NOₓ plays a key role in the formation of smog and acid rain and contributes to respiratory diseases. o Sulfur Dioxide (SO₂) SO₂ is a gas produced primarily from burning coal and oil in power plants and industrial facilities. It reacts with water vapor in the atmosphere to form sulfuric acid, leading to acid rain, which damages ecosystems, buildings, and aquatic environments.  Atmospheric Chemistry 1- Primary Pollutants: o Volatile Organic Compounds (VOCs) VOCs are organic chemicals that can vaporize into the atmosphere. They come from vehicle emissions, industrial processes, and the use of products like paints and solvents. VOCs are major contributors to the formation of ground-level ozone and smog. o Lead (Pb) Lead used to be a major air pollutant from gasoline, but its use has significantly decreased since the introduction of unleaded fuel. However, lead emissions still occur from industries such as smelting, waste incineration, and battery manufacturing. 1- Atmospheric L2  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Acid rain refers to any form of precipitation (rain, snow, fog, or even dust) that contains elevated levels of acids, primarily sulfuric (H₂SO₄) and nitric acid (HNO₃). It forms when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ), which are emitted from human activities and natural sources, react with water vapor in the atmosphere.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Sources of Acid Rain 1.Human Activities: a) Burning of fossil fuels: Power plants, factories, and motor vehicles burn coal, oil, and gas, releasing large quantities of SO₂ and NOₓ. b)Industrial processes: Refineries, smelters, and chemical plants also emit sulfur and nitrogen compounds into the atmosphere. 2. Natural Sources: a) Volcanoes: Release large amounts of SO₂ during eruptions. b)Biological processes: Decomposition of organic matter in wetlands and marine environments can emit sulfur gases. c)Forest fires and lightning: Both contribute to NOₓ emissions.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Chemical Reactions Leading to Acid Rain ❑ when SO₂ and NOₓ are released into the atmosphere, they undergo chemical transformations: 1.Sulfur Dioxide Reactions SO₂ reacts with oxygen (O₂) and water vapor (H₂O) in the atmosphere to form sulfuric acid (H₂SO₄). SO 2 + 0.5 O 2 + H 2O → H 2SO The resulting sulfuric acid then dissolves in water droplets in clouds, leading to acidic precipitation.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Chemical Reactions Leading to Acid Rain 1.Nitrogen Oxides Reactions : NOₓ gases, especially nitrogen dioxide (NO₂), react with water vapor to form nitric acid (HNO₃). 4NO 2 + O 2 + 2H 2O → 4HNO3 Like sulfuric acid, nitric acid also dissolves in water and falls as acid rain.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain pH of Acid Rain The pH scale measures how acidic or basic a substance is, ranging from 0 to 14, with 7 being neutral. Natural rainwater is slightly acidic, with a pH of around 5.6 due to the presence of dissolved carbon dioxide (CO₂), which forms carbonic acid (H₂CO₃). CO 2 + 0.5 O 2 + H2O → H2CO3 Acid rain typically has a pH between 4.2 and 4.4, but it can be even lower in areas with high pollution levels.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Environmental Effects of Acid Rain 1.Aquatic Ecosystems a) Acidification of lakes and streams: Acid rain lowers the pH of water bodies, leading to harmful effects on aquatic life. Fish, amphibians, and other aquatic organisms are sensitive to changes in pH. b)Loss of biodiversity: Many species, particularly fish, are highly sensitive to acidic conditions. Acid rain can lead to the death of fish populations and the loss of biodiversity. c)Aluminum release: Acid rain can cause the leaching of aluminum from soils into water bodies. Increased aluminum concentrations are toxic to fish and other aquatic species.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Environmental Effects of Acid Rain 2. Soil and Forests a) Soil acidification: Acid rain leaches important nutrients (e.g., calcium, magnesium, and potassium) from the soil, reducing fertility and affecting plant growth. b)Damage to forests: In forests, acid rain can weaken trees by dissolving nutrients in the soil and damaging leaves, making them more susceptible to disease, extreme weather, and pests. c)Nutrient depletion: Long-term exposure to acid rain can strip soils of essential nutrients, leading to stunted growth in forests and reduced agricultural productivity.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Environmental Effects of Acid Rain 3. Buildings and Infrastructure a) Corrosion of buildings and monuments: Acid rain accelerates the deterioration of structures made from limestone, marble, and concrete. Sulfuric acid reacts with calcium carbonate in these materials, causing them to wear away. CaCO3 + H2SO4→ CaCO3 + H2O + CO2 Historic buildings, statues, and cultural landmarks are particularly affected by acid rain damage.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Environmental Effects of Acid Rain 4. Human Health a) Respiratory issues: Although acid rain itself doesn’t directly harm humans, the pollutants (SO₂ and NOₓ) that cause acid rain can lead to respiratory problems, such as asthma, bronchitis, and other lung diseases, especially in children and the elderly. b) Fine particulate matter: SO₂ and NOₓ can form fine particles (PM₂.₅), which can penetrate deep into the lungs, causing health issues  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain Economic Impacts of Acid Rain 1. Damage to agriculture and forestry: Reduced soil fertility and damage to crops and forests can lead to economic losses in farming and logging industries. 2. Repair and maintenance costs: The corrosion of buildings, bridges, and infrastructure requires costly repairs, particularly in urban areas with high levels of air pollution. 3. Loss of fisheries: The acidification of lakes and rivers can destroy fish populations, affecting commercial and recreational fishing industries.  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain How to overcome acid rain a) Flue Gas Desulfurization (FGD): Power plants and industrial facilities use scrubbers to remove SO2 from exhaust gases. One common method is the use of wet scrubbers that use a slurry of limestone to react with SO₂, forming gypsum. SO2 + CaCO3 + O2 + 2H2O→ CaSO4.2H2O + CO2 a) Catalytic converters: Installed in vehicles, catalytic converters reduce nitrogen oxide emissions by converting them into nitrogen (N₂) and oxygen (O₂).  Atmospheric Chemistry 2- Secondary Pollutants: o Acid rain How to overcome acid rain c) Low-sulfur fuels: Switching to low-sulfur coal, oil, and natural gas reduces SO₂ emissions. d) Renewable energy: The use of wind, solar, and hydroelectric power reduces the burning of fossil fuels, which are the primary sources of acid rain-causing pollutants.  Atmospheric Chemistry 2- Secondary Pollutants: o Particulate Matter (PM) PM₁₀: Particles with diameters less than 10 micrometers (e.g., dust, pollen). PM₂.₅: Finer particles with diameters less than 2.5 micrometers, often resulting from combustion processes. These particles can penetrate deep into the lungs, causing respiratory and cardiovascular issues. Sources include burning fossil fuels, industrial emissions, and natural sources like wildfires.  Atmospheric Chemistry 2- Secondary Pollutants: o Particulate Matter (PM) PM₁₀: Particles with diameters less than 10 micrometers (e.g., dust, pollen). PM₂.₅: Finer particles with diameters less than 2.5 micrometers, often resulting from combustion processes. These particles can penetrate deep into the lungs, causing respiratory and cardiovascular issues. Sources include burning fossil fuels, industrial emissions, and natural sources like wildfires.  Atmospheric Chemistry 2- Secondary Pollutants: o Ground-level ozone (O₃) Ground-level ozone (O₃) is a harmful air pollutant that forms near the Earth's surface, primarily as a result of human activities. Unlike ozone in the stratosphere, which forms the protective ozone layer that shields the Earth from harmful ultraviolet (UV) radiation, ground-level ozone is a key component of smog and poses significant risks to human health, ecosystems, and materials.  Atmospheric Chemistry 2- Secondary Pollutants: o Ground-level ozone (O₃) Formation of Ground-Level Ozone Ground-level ozone is forms through complex chemical reactions involving precursor pollutants in the presence of sunlight. These precursor pollutants include: Nitrogen oxides (NOₓ): Emitted from vehicles, power plants, and industrial facilities. Volatile organic compounds (VOCs): Emitted from vehicle exhaust, industrial solvents, gasoline vapors, and certain plants.  Atmospheric Chemistry 2- Secondary Pollutants: o Ground-level ozone (O₃) Formation of Ground-Level Ozone The formation of ground-level ozone occurs primarily through photochemical reactions: 1.Nitrogen dioxide (NO₂) is broken down by sunlight into nitrogen monoxide (NO) and an oxygen atom (O): NO2​ + hν → NO + O. 2.The free oxygen atom (O) reacts with molecular oxygen (O₂) to form ozone (O₃): O2​ + O. → O3 3. VOCs play a role in stabilizing the ozone molecule, preventing its immediate breakdown, which helps maintain higher ozone concentrations at ground level.  Atmospheric Chemistry 2- Secondary Pollutants: o Ground-level ozone (O₃) How to over come ground-level ozone (O₃) 1. Transportation improvements: Shifting from gasoline and diesel-powered vehicles to electric and hybrid vehicles can reduce NOₓ and VOC emissions. Reducing the number of vehicles on the road decreases traffic emissions, which are a major source of ozone precursors. 2. Reducing solvent use: Limiting the use of paints, cleaning products, and other products that emit VOCs can help reduce ozone formation.  Atmospheric Chemistry 2- Secondary Pollutants: o Ground-level ozone (O₃) How to over come ground-level ozone (O₃) 2. Energy efficiency: Reducing energy consumption and promoting renewable energy sources can reduce emissions from power plants. Using energy-efficient appliances, reducing electricity use during peak hours, and choosing cleaner energy sources can help lower emissions. 4. Industrial regulations: Industries can reduce emissions by adopting cleaner technologies and using scrubbers and catalytic converters to remove pollutants before they are released into the atmosphere.Energy efficiency: (e.g., wind, solar) 1- Atmospheric L3  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Greenhouse gases play a critical role in regulating the Earth’s climate by trapping heat in the atmosphere. The Greenhouse Effect is a natural process that warms the Earth's surface. When the Sun’s energy reaches the Earth, some of it is reflected back to space, and the rest is absorbed by the planet’s surface. This absorbed energy is then re- radiated as heat (infrared radiation). However, human activities have intensified the greenhouse effect by increasing the concentration of GHGs in the atmosphere, leading to global warming and climate change.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Key Greenhouse Gases 1.Carbon Dioxide (CO₂): 1.Source: Burning fossil fuels (coal, oil, natural gas), deforestation, industrial processes, and cement production. 2.Contribution: CO₂ is the primary greenhouse gas emitted through human activities and is responsible for about 75% of global GHG emissions. Its longevity in the atmosphere, lasting hundreds to thousands of years, makes it a key driver of long-term climate change.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Key Greenhouse Gases 2. Methane (CH₄): 1.Source: Agriculture (livestock digestion), rice paddies, landfills, natural gas extraction, and decaying organic matter. 2.Contribution: Methane is about 25 times more effective at trapping heat than CO₂ over a 100-year period, although it has a shorter atmospheric lifetime (around 12 years).  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Key Greenhouse Gases 3. Nitrous Oxide (N₂O): 1.Source: Agriculture (fertilizer use), industrial processes, and combustion of fossil fuels and biomass. 2.Contribution: N₂O has a global warming potential about 298 times greater than CO₂ over a 100-year period and lasts for about 100 years in the atmosphere.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Key Greenhouse Gases 4. Fluorinated Gases: (e.g., hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride): 1.Source: Industrial activities, refrigeration, air conditioning, and electrical transmission. 2.Contribution: These synthetic gases are much more potent than CO₂ in terms of their heat-trapping capacity. Some can persist in the atmosphere for thousands of years.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Key Greenhouse Gases 5. Water Vapor (H₂O): 1.Source: Natural processes, including evaporation and transpiration. 2.Contribution: Water vapor is the most abundant greenhouse gas, but its concentration is controlled by temperature rather than direct human activity. However, as the atmosphere warms, it can hold more water vapor, which amplifies the greenhouse effect in a process known as positive feedback.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects The increased concentration of greenhouse gases due to human activity has led to significant changes in the Earth's climate system, with wide-ranging effects: 1. Global Warming Rising Temperatures: The Earth’s average surface temperature has increased by approximately 1.1°C since the late 19th century. Most of this warming has occurred in the past few decades, largely driven by human activities. Heatwaves: Increased temperatures lead to more frequent and severe heatwaves, affecting human health, ecosystems, and agriculture. Extreme heat events are becoming more common and lasting longer.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 2. Melting of Ice and Snow Polar Ice Melt: The Arctic is warming twice as fast as the global average, leading to the rapid melting of sea ice. Glaciers and ice sheets in Greenland and Antarctica are also losing mass. Sea-Level Rise: As ice sheets and glaciers melt, they contribute to rising sea levels. Global sea levels have risen by about 20 cm since 1900, and the rate of rise is accelerating. Loss of Snowpack: Warmer temperatures reduce snowpack in mountainous regions, which impacts freshwater availability for millions of people, particularly in areas like the Himalayas, Andes, and western North America.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 3. Changing Weather Patterns More Intense Storms: Warmer air and oceans provide more energy for storms. These storms are becoming stronger, with heavier rainfall, increasing the risk of flooding and storm surges. Shifting Precipitation Patterns: Some regions are experiencing increased rainfall and more severe storms, while others are becoming drier. This shift leads to longer and more intense droughts in some areas, while others may face increased flooding. More Frequent Floods: Warmer temperatures cause more rapid evaporation and increase the capacity of the atmosphere to hold moisture, leading to heavier rainfall and increased flood risks.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 4. Ocean Changes Ocean Warming: Over 90% of the excess heat trapped by greenhouse gases has been absorbed by the oceans, leading to warmer water temperatures. This affects marine ecosystems and contributes to sea-level rise. Ocean Acidification: Increased CO₂ in the atmosphere is absorbed by the oceans, where it reacts with seawater to form carbonic acid, lowering the pH of the ocean. This process, known as ocean acidification, negatively impacts marine life, particularly species that rely on calcium carbonate to form shells and skeletons, like corals and mollusks.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 5. Ecosystem Disruption Species Migration: Many species are shifting their ranges toward cooler habitats. This migration can disrupt ecosystems, leading to mismatches between species and their food sources or breeding environments. Biodiversity Loss: Climate change is placing additional stress on already vulnerable species, contributing to higher extinction rates. Polar bears, penguins, amphibians, and many plant species are particularly at risk. Forest Health: Higher temperatures and changes in precipitation patterns can stress forests, making them more susceptible to pests, diseases, and wildfires. Increased wildfires are already being seen in regions like the Amazon, Australia, and California.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 6. Impact on Human Health Heat-Related Illnesses: More frequent and severe heatwaves increase the risk of heatstroke, dehydration, and other heat-related illnesses. Spread of Diseases: Warmer temperatures and changing precipitation patterns can expand the range of vector-borne diseases, such as malaria, dengue, and Lyme disease. Air Quality: Higher temperatures contribute to the formation of ground-level ozone, a harmful air pollutant.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 7. Food and Water Security Agricultural Disruptions: Climate change affects crop yields by altering growing seasons, increasing the frequency of extreme weather events, and intensifying droughts. Water Scarcity: Glacial melt, reduced snowpack, and changing precipitation patterns threaten freshwater supplies in many regions. This creates challenges for drinking water, agriculture, and energy production in areas that rely on hydroelectric power.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect Climate Change Effects 8. Economic Impacts Damage to Infrastructure: Rising sea levels, stronger storms, and more frequent flooding can damage buildings, transportation networks, and energy infrastructure, leading to costly repairs and economic losses. Displacement: Communities in low-lying coastal areas and small island nations are at risk of being displaced due to rising sea levels.  Atmospheric Chemistry ❑ Greenhouse gases and climate change effect How to reduce greenhouse emission to overcome climate change? Transition to Renewable Energy: Shifting from fossil fuels to renewable energy sources such as solar, wind, and hydropower can significantly reduce CO₂ emissions. Energy Efficiency: Improving the energy efficiency of buildings, transportation, and industry reduces the amount of energy needed, thus cutting emissions. Carbon Sequestration: Technologies like carbon capture and storage can remove CO₂ from the atmosphere. Natural carbon sinks, such as forests, also play a vital role in absorbing CO₂. Reforestation and Afforestation: Planting trees and restoring degraded forests can sequester CO₂ and restore ecosystems. 2- Hydrosphere L4  Hydrosphere chemistry ❑ Hydrosphere chemistry is a branch of environmental chemistry that deals with the chemical composition, reactions, and processes occurring within the hydrosphere, which involve all water on Earth in various forms, including oceans, rivers, lakes, groundwater, and even atmospheric water vapor. ❑ The chemistry of the hydrosphere is essential for understanding water quality, marine ecosystems, and the interactions between water and the Earth's atmosphere, lithosphere, and biosphere. Hydrosphere chemistry  Hydrosphere chemistry Components of the Hydrosphere 1- Oceans: Make up about ≈ 97% of the Earth's water. They contain salts, minerals, gases, and organic matter. 2- Freshwater Systems: Rivers, lakes, and groundwater make up the remaining 3%, with less than 1% of it being accessible for human use. 3- Atmospheric Water: Water vapor, clouds, and precipitation play a role in the water cycle and influence both weather and climate. 5- Ice and Glaciers: Frozen water stores, especially in polar regions, represent a significant part of the Earth's freshwater.  Hydrosphere chemistry Importance of Hydrosphere Chemistry 1.Ecosystem Health: The chemical composition of water affects the distribution and abundance of aquatic species, from phytoplankton to fish. Changes in water chemistry can disrupt entire ecosystems, especially sensitive habitats like coral reefs and freshwater lakes. 2.Water Quality: Understanding water chemistry helps in assessing and managing water quality for human use, including drinking, agriculture, and recreation. Factors like salinity, pH, nutrient levels, and pollutants must be monitored to ensure safe water supplies.  Hydrosphere chemistry Importance of Hydrosphere Chemistry 3. Global Climate Regulation: Oceans play a key role in regulating the Earth’s climate by absorbing heat and carbon dioxide from the atmosphere. Changes in ocean chemistry, such as ocean acidification and warming, have profound impacts on global climate patterns. 4. Natural Resource Management: Knowledge of hydrosphere chemistry is critical for managing natural resources like fisheries, freshwater supplies, and mineral deposits. Understanding the chemical interactions in water can help in the sustainable use of these resources.  Hydrosphere chemistry ❑ Water quality Water quality refers to the chemical, physical, and biological characteristics of water, which determine its suitability for various uses such as drinking, recreational activities, agriculture, and industrial processes. Several factors are used to assess water quality, and they can be broadly categorized into a) Physical factors b) Chemical factors c) Biological Factors  Hydrosphere chemistry ❑ Water quality a) Physical factors: Physical parameters influence the appearance and physical properties of water. i. Temperature: Importance: Temperature affects water chemistry and the metabolic rates of aquatic organisms. Warmer water holds less dissolved oxygen, which can stress aquatic life. Sources of Change: Natural sunlight, industrial discharges, and power plants that release heated water (thermal pollution).  Hydrosphere chemistry ❑ Water quality a) Physical factors: ii. Turbidity: Definition: A measure of how clear or cloudy water is, determined by the amount of suspended solids such as silt, clay, algae, and organic matter. Importance: High turbidity reduces light penetration, affecting photosynthesis in aquatic plants and can also clog the gills of fish. Sources: Soil erosion, urban runoff, construction activities, and algae growth.  Hydrosphere chemistry ❑ Water quality a) Physical factors: iii. Color: Definition: Natural or unnatural color in water due to dissolved or suspended substances, such as decaying organic matter or industrial pollution. Importance: Water color may indicate the presence of contaminants. Natural color (from organic materials) is typically harmless but can affect aesthetics. iv. Odor: Definition: Water may have different odors depending on its quality. For example, the presence of hydrogen sulfide gives off a rotten egg smell. Importance: Unpleasant odors often signal the presence of organic decay, sewage, or industrial waste.  Hydrosphere chemistry ❑ Water quality a) Physical factors: v. Taste: Importance: Taste is a key factor in determining the potability of water. Contaminants such as metals, chlorides, and chemicals may cause off-tastes. vi. Total Suspended Solids (TSS): Definition: The total amount of solid particles suspended in the water. Importance: High TSS levels can reduce water quality, affect aquatic organisms, and indicate erosion or runoff pollution.  Hydrosphere chemistry ❑ Water quality a) Chemical Factors: These parameters help determine the chemical composition and potential contamination of water. i) pH: Definition: A measure of how acidic or basic the water is on a scale of 0 to 14, with 7 being neutral. Importance: pH affects the solubility of metals and nutrients in water. Most aquatic organisms prefer water with a pH between 6.5 and 8.5. Sources of Change: Acid rain, industrial discharges, and natural processes like the decomposition of organic material.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: ii) Dissolved Oxygen (DO): Definition: The amount of oxygen dissolved in water, critical for the survival of fish and other aquatic organisms. Importance: High levels of DO are necessary for healthy ecosystems. Low DO levels can result in "dead zones" where aquatic life cannot survive. Sources of Change: Temperature, organic pollution (such as sewage), and photosynthesis by aquatic plants.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: iii) Biochemical Oxygen Demand (BOD): Definition: The amount of oxygen required by microorganisms to decompose organic matter in water over a specified period (usually 5 days). Importance: High BOD levels indicate high levels of organic pollution, which can deplete oxygen and harm aquatic life. Sources: Sewage, industrial waste, and agricultural runoff.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: iv) Chemical Oxygen Demand (COD): Definition: A measure of the total amount of chemicals (both organic and inorganic) in water that can consume oxygen. Importance: Like BOD, high COD levels indicate pollution and a potential oxygen deficiency in water bodies.  Hydrosphere chemistry ❑ Water quality  Hydrosphere chemistry ❑ Water quality  Hydrosphere chemistry ❑ Water quality  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: v) Total Dissolved Solids (TDS): Definition: The total concentration of dissolved substances (minerals, salts, metals) in water. Importance: High TDS levels can affect water taste and health. High mineral content may cause scaling in pipes and affect crop growth when used in agriculture. Sources: Natural mineral deposits, agricultural runoff, industrial discharge, and saltwater intrusion.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: vi) Nutrients (Nitrogen and Phosphorus): Definition: Nitrogen (in the form of nitrates or ammonium) and phosphorus are essential nutrients for aquatic plants, but excessive amounts can lead to water quality issues. Importance: Excess nutrients contribute to eutrophication, causing algal blooms and dead zones due to oxygen depletion. Sources: Agricultural runoff (fertilizers), sewage, and industrial waste.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: vii) Heavy Metals (e.g., Lead, Mercury, Arsenic, Cadmium): Importance: Heavy metals are toxic to both aquatic life and humans, even at low concentrations. They can accumulate in organisms over time, leading to bioaccumulation and biomagnification. Sources: Industrial discharge, mining activities, and improper disposal of waste.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: viii) Salinity: Definition: The concentration of salts in water. Importance: High salinity levels affect water’s suitability for drinking, agriculture, and aquatic life. Some species are sensitive to changes in salinity. Sources: Natural processes (evaporation, saltwater intrusion) and human activities like irrigation runoff and wastewater discharge.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: ix) Pesticides and Herbicides: Definition: Chemical substances used in agriculture to control pests and weeds. Importance: Pesticides can be toxic to aquatic life and may accumulate in the food chain, posing risks to human health. Sources: Agricultural runoff, urban runoff, and improper disposal.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: x) Organic Pollutants: Definition: Pollutants like petroleum products, solvents, and detergents. Importance: Organic pollutants can be toxic to aquatic organisms and may persist in the environment, causing long-term damage. Sources: Industrial discharge, spills, and urban runoff.  Hydrosphere chemistry ❑ Water quality b) Chemical Factors: x) Organic Pollutants: Definition: Pollutants like petroleum products, solvents, and detergents. Importance: Organic pollutants can be toxic to aquatic organisms and may persist in the environment, causing long-term damage. Sources: Industrial discharge, spills, and urban runoff. 2- Hydrosphere L5  Hydrosphere chemistry ❑ Water pollution Water pollution refers to the contamination of water bodies by harmful substances, often as a result of human activities. Pollutants in water can have serious consequences for aquatic life, ecosystems, and human health. The sources of water pollution are diverse, and the effects can be both immediate and long-term.  Hydrosphere chemistry ❑ Water pollution Types of Water Pollution 1.Chemical Pollution: 1.Sources: Industrial discharges, agricultural runoff (pesticides and fertilizers), household chemicals, and pharmaceuticals. 2.Examples: Heavy metals (like mercury, lead, and arsenic), oil spills, synthetic chemicals (such as detergents, solvents), and nutrients (like nitrogen and phosphorus). 3.Effects: Toxic chemicals can poison aquatic organisms, disrupt ecosystems, and contaminate drinking water supplies, leading to health problems like cancer, reproductive issues, and neurological disorders.  Hydrosphere chemistry ❑ Water pollution Types of Water Pollution 2. Biological Pollution: 1.Sources: Sewage discharge, animal waste, and agricultural runoff containing organic matter. 2.Examples: Pathogens like bacteria (E. coli), viruses, protozoa, and parasites. 3.Effects: Biological pollution can lead to waterborne diseases, including cholera, typhoid, and dysentery, which are especially dangerous in areas with inadequate sanitation and water treatment systems.  Hydrosphere chemistry ❑ Water pollution Types of Water Pollution 3. Thermal Pollution: 1.Sources: Power plants and industrial facilities that use water for cooling and discharge the heated water back into water bodies. 2.Effects: Higher water temperatures can reduce dissolved oxygen levels, affecting aquatic life and causing thermal shock to organisms, leading to death and biodiversity loss.  Hydrosphere chemistry ❑ Water pollution Types of Water Pollution 4. Nutrient Pollution: 1.Sources: Agricultural runoff (excessive use of fertilizers), wastewater, and stormwater. 2.Examples: Nitrogen and phosphorus compounds. 3.Effects: Excess nutrients lead to the overgrowth of algae (algal blooms), which can produce toxins and deplete oxygen in the water when the algae die and decompose, resulting in dead zones where aquatic life cannot survive.  Hydrosphere chemistry ❑ Water pollution Types of Water Pollution 5. Sediment Pollution: 1.Sources: Soil erosion from construction sites, deforestation, mining, and agriculture. 2.Effects: Sediment can smother aquatic habitats, disrupt the food chain, and reduce the clarity of water, affecting photosynthesis and reducing oxygen levels in the water. 6. Radioactive Pollution: 1.Sources: Nuclear power plants, medical and research facilities, and improper disposal of radioactive waste. 2.Effects: Radioactive pollutants can cause long-term environmental damage, with effects on aquatic organisms' genetic material, potentially leading to mutations, cancer, and reproductive issues.  Hydrosphere chemistry ❑ Water pollution Major Sources of Water Pollution 1.Industrial Discharges: 1.Factories and industries release a variety of pollutants, including heavy metals, toxic chemicals, and thermal pollution, directly into water bodies or indirectly through runoff. 2.Agricultural Runoff: 1.Excess fertilizers, pesticides, herbicides, and animal waste from farms are washed into nearby water bodies by rain, contributing to nutrient pollution, pesticide contamination, and sediment buildup.  Hydrosphere chemistry ❑ Water pollution Major Sources of Water Pollution 3. Wastewater and Sewage: 1.Domestic sewage and untreated or partially treated wastewater from urban areas can introduce pathogens, organic matter, and nutrients into water systems. Poor sanitation systems in developing regions contribute significantly to biological pollution. 4. Oil Spills: 1.Oil spills from ships, offshore drilling rigs, and accidents release crude oil or petroleum products into oceans and seas, causing severe damage to marine life and coastal ecosystems.  Hydrosphere chemistry ❑ Water pollution Major Sources of Water Pollution 5. Plastic Pollution: Plastics, including microplastics (tiny plastic particles), are major pollutants in water bodies. They come from discarded packaging, fishing gear, and synthetic clothing fibers, affecting marine animals and potentially entering the human food chain. 6. Mining and Quarrying: Mining operations can lead to the contamination of water bodies with heavy metals and toxic chemicals, while quarrying can increase sediment loads in rivers and streams.  Hydrosphere chemistry ❑ Water pollution Effects of Water Pollution 1. Impact on Aquatic Ecosystems: 1.Biodiversity Loss: Water pollution can kill fish, plants, and other aquatic organisms, disrupting entire ecosystems. Species sensitive to pollutants may be wiped out, reducing biodiversity. 2.Food Chain Disruption: Pollutants like heavy metals and microplastics can accumulate in organisms, moving up the food chain and affecting larger predators, including humans. 3.Dead Zones: Nutrient pollution can cause hypoxic zones (areas with low oxygen), where most marine life cannot survive. Examples include the Gulf of Mexico's "Dead Zone."  Hydrosphere chemistry ❑ Water pollution Effects of Water Pollution 2. Human Health Hazards: 1.Waterborne Diseases: Contaminated water can carry pathogens that cause illnesses like cholera, dysentery, and hepatitis A. Lack of access to clean water is a major public health issue in many developing countries. 2.Toxic Contamination: Long-term exposure to polluted water (containing substances like mercury, arsenic, and lead) can lead to chronic health conditions, including cancer, kidney damage, and neurological disorders. 3.Impact on Drinking Water: Contaminated water sources can make drinking water unsafe, posing a risk to millions of people worldwide.  Hydrosphere chemistry ❑ Water pollution Effects of Water Pollution 3. Economic Impact: 1.Fishing and Aquaculture: Water pollution can devastate fisheries, both wild and farmed, resulting in economic losses for communities that rely on fishing for food and income. 2.Tourism: Polluted beaches, rivers, and lakes can deter tourists, leading to economic losses for regions dependent on tourism. 3.Increased Water Treatment Costs: Water pollution increases the cost of treating water to make it safe for drinking and other uses.  Hydrosphere chemistry ❑ Water pollution Effects of Water Pollution 4. Environmental Impact: 1.Soil Contamination: Polluted water used for irrigation can degrade soil quality, reducing agricultural productivity and harming crops. 2.Climate Change: Pollutants like nitrogen oxides (NOₓ) and methane (CH₄) not only pollute water but also contribute to climate change, exacerbating issues like sea-level rise and more frequent extreme weather events, which further affect water quality.  Hydrosphere chemistry ❑ Water pollution Control and Prevention of Water Pollution 1.Wastewater Treatment: Municipal wastewater treatment plants remove contaminants from sewage and industrial wastewater before it is released into the environment. Improving wastewater infrastructure is critical in preventing water pollution. 2.Agricultural Best Practices: Farmers can reduce runoff by using less fertilizer, adopting crop rotation, planting cover crops to reduce erosion, and building buffer strips (vegetation planted along waterways) to filter runoff.  Hydrosphere chemistry ❑ Water pollution Control and Prevention of Water Pollution 3. Industrial Regulations: 1.Governments can impose stricter regulations on industries, requiring them to treat effluents before discharge and limiting the release of toxic substances into water bodies. 4. Oil Spill Prevention and Cleanup: 1.Stronger regulations on offshore drilling, shipping, and oil transport can help prevent spills. Technologies like booms, skimmers, and dispersants can help clean up oil spills when they do occur.  Hydrosphere chemistry ❑ Water pollution Control and Prevention of Water Pollution 5. Reducing Plastic Pollution: Bans on single-use plastics, improving waste management systems, and promoting recycling can help reduce plastic pollution in water bodies. 6. Public Awareness and Education: Educating the public about the causes and consequences of water pollution, as well as encouraging responsible waste disposal, can lead to changes in behavior that reduce water contamination. L6  Biogeochemical Cycles Biogeochemical cycles refer to the movement and transformation of chemical elements between living organisms (bio), the Earth's geological systems (geo), and chemical processes. These cycles ensure the availability of essential nutrients for life and maintain the balance of ecosystems. The key biogeochemical cycles include: 1- carbon cycle. 2- nitrogen cycle. 2- sulfur cycle. 4- water cycle. 5- phosphorus cycle. Carbon cycle  Carbon cycle The carbon cycle describes the movement of carbon among the Earth's atmosphere, oceans, soil, and living organisms. Carbon is essential for life and is a major component of biological molecules, such as proteins, carbohydrates, and lipids. Main Processes in the Carbon Cycle: 1- Photosynthesis: Plants, algae, and cyanobacteria absorb carbon dioxide (CO₂) from the atmosphere and convert it into organic compounds (glucose) using sunlight. This process removes CO₂ from the atmosphere. 6CO2 + 6H2O + sunlight → C6H12O6 + 6O2  Carbon cycle Main Processes in the Carbon Cycle: 2- Respiration: Organisms (plants, animals, and microbes) release carbon dioxide back into the atmosphere through cellular respiration as they convert organic molecules into energy. C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy 3- Decomposition: Dead plants, animals, and waste products are broken down by decomposers (bacteria and fungi), releasing carbon into the soil or water as organic matter decomposes and into the atmosphere as CO₂ or methane (CH₄).  Carbon cycle Main Processes in the Carbon Cycle: 3- Combustion: The burning of fossil fuels (coal, oil, and natural gas) or biomass releases carbon dioxide into the atmosphere. This is a major source of anthropogenic carbon emissions, contributing to climate change. 4- Ocean-Atmosphere Exchange: CO₂ dissolves in oceans, forming H₂CO₃. The ocean acts as both a sink and source of atmospheric CO₂. Marine organisms also use dissolved carbon to form shells and skeletons (e.g., calcium carbonate). 5- Sedimentation and Fossilization: Over long periods, some carbon is stored in the form of fossil fuels (coal, oil, gas) or sedimentary rocks like limestone. This carbon is released back into the cycle through weathering or human activities (e.g., burning fossil fuels).  Carbon cycle Key Components of the Carbon Cycle: Atmosphere: Contains CO₂ and CH₄, both greenhouse gases. Oceans: Dissolved carbon in the form of CO₂, bicarbonates (HCO₃⁻), and carbonates (CO₃²⁻). Terrestrial Biosphere: Plants and animals store carbon in organic molecules. Lithosphere: Carbon is stored in fossil fuels and sedimentary rocks. *Human Impact: Burning fossil fuels, deforestation, and industrial activities increase atmospheric CO₂ levels, contributing to global warming and climate change. Nitrogen Cycle  Nitrogen Cycle The nitrogen cycle describes the movement of nitrogen between the atmosphere, living organisms, and the soil. Nitrogen is a critical element in proteins, nucleic acids (DNA, RNA), and other essential biological molecules. Main Processes in the Carbon Cycle: 1- Nitrogen Fixation: Atmospheric nitrogen (N₂), which is inert and unavailable to most organisms, is converted into ammonia (NH₃) or ammonium (NH₄⁺) by nitrogen-fixing bacteria, either free-living or in symbiosis with plant roots (e.g., legumes). N2 + 8H+ + 8e− → 2NH3 + H2 2- Nitrification: NH4+ is oxidized by nitrifying bacteria into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), which can be absorbed by plants. NH + → NO₂⁻ → NO₃⁻ 4  Nitrogen Cycle Main Processes in the Carbon Cycle: 3- Assimilation: Plants take up nitrates from the soil and incorporate them into organic molecules (proteins, nucleic acids). Animals obtain nitrogen by consuming plants or other animals. 4- Ammonification (Decomposition): Organic nitrogen in dead organisms and waste products is converted back into ammonium by decomposers (bacteria and fungi). 5- Denitrification: In anaerobic conditions, denitrifying bacteria convert nitrates back into nitrogen gas (N₂), releasing it into the atmosphere and completing the cycle. NO₃⁻ → NO₂⁻ → 𝑁2𝑂 → 𝑁2 Sulfur Cycle  Sulfur Cycle The sulfur cycle describes the movement of sulfur between the Earth's atmosphere, oceans, soil, and living organisms. Sulfur is essential for the synthesis of proteins and enzymes and is a component of some vitamins and amino acids (e.g., methionine). Main Processes in the Sulfur Cycle: 1- Weathering of Rocks: Sulfur is released from rocks as sulfate (SO₄²⁻) through weathering and carried to soils and water bodies. 2- Assimilation by Plants: Plants and microorganisms take up sulfate from the soil and incorporate it into organic molecules, such as amino acids. 3- Decomposition: When plants and animals die, organic sulfur is released back into the soil, where it is converted back into inorganic forms like sulfate or hydrogen sulfide (H₂S) by bacteria.  Sulfur Cycle Main Processes in the Sulfur Cycle: 4- Sulfur Oxidation: In aerobic conditions, sulfur bacteria oxidize H₂S to sulfate SO₄²⁻, making it available for plants again. H₂S + 2O2 → SO4− + H+ 5- Sulfur Reduction (Anaerobic Conditions): In environments without oxygen, sulfate-reducing bacteria convert sulfate into hydrogen sulfide gas (H₂S), which is released into the atmosphere or used by sulfur-oxidizing bacteria. SO4− + 8H+ + 8e− → H₂S + 4H2O 6- Volcanic Activity: Volcanic eruptions release SO₂ and H₂S into the atmosphere, where they can form sulfuric acid (H₂SO₄) and return to the Earth's surface as acid rain.  Sulfur Cycle Key Components of the Sulfur Cycle: Atmosphere: Contains sulfur gases like sulfur dioxide (SO₂) and hydrogen sulfide (H₂S), which contribute to acid rain. Soil and Water: Sulfate (SO₄²⁻) is the most common form of sulfur available for plant uptake. Living Organisms: Sulfur is a component of certain amino acids, vitamins, and proteins. *Human Impact: Burning of fossil fuels and industrial processes release large amounts of sulfur dioxide (SO₂), contributing to acid rain, which can harm ecosystems and degrade buildings and structures.