1 Summary New Environment Class 11 ## A BRIEF OVERVIEW OF THE PREVIOUS CLASS (1:15 PM) ## WATER POLLUTION (1:20 PM) - Any undesirable change in physical, chemical, or biological characteristics of air, land, water, or soil is called pollution - The agents bringing the change are called pollutants - Undesirable changes in the quality of water through the addition of undesirable substances or undesirable levels of existing compounds are called water pollution - ***Source of water pollution*** - | | | | --- | --- | | ***Point Source*** | ***Non-Point Source*** | | It has a single identifiable source of pollution | There is no single identifiable source and the pollutants originate from a very wide area | | The pollutants enter the water bodies at specific locations directly from the source | The pollutants enter the water bodies at multiple locations from wide areas | | They can be regulated and monitored easily | They can not be regulated or monitored easily | | E.g. Industrial effluents, municipal sewage outlets, oil spills, etc. | E.g. Urban runoff, agricultural runoff, atmospheric deposition (like dried deposition of acid rain), etc. | - ***Impacts of some specific pollutants*** - | | | | --- | --- | | ***Pollutants*** | ***Impact*** | | Mercury | Minimata disease, dropsy (particularly in fish) | | Lead | Dyslexia | | Cadmium | Itai-Itai | | Fluoride | Fluorosis | | Arsenic | Black-foot disease | | Chromium | Allergies and asthma | | Nickle | skin issues, pneumonia | | Uranium | Cancer, kidney failure | | Iron | Skin issues | | Nitrate | Blue-baby syndrome | - ***Impacts of water pollution*****(1:54 PM)** - *==Decreased dissolved oxygen==* - The amount of oxygen dissolved in the water is called dissolved oxygen - It is measured in mg/liter - A non-polluted water contains at least 8 mg/l of dissolved oxygen - With pollution, oxygen demand increases - Oxygen demand has an inverse relation with dissolved oxygen - Oxygen demand can be classified into biochemical oxygen demand (BOD) and chemical oxygen demand (COD) - Biochemical oxygen demand represents the amount of oxygen consumed by bacteria and other microorganisms to decompose biodegradable organic material present in the water under aerobic condition - Chemical oxygen demand (COD): It is the amount of oxygen consumed to break down both biodegradable and non-biodegradable organic matter present in water through chemical oxidation process - While COD measures oxygen demand for all organic matter, BOD measures only biodegradable organic matter, therefore, COD is always greater than BOD - Both BOD and COD indicate the level of water pollution and harm to aquatic ecosystem - *==Eutrophication==* - The enrichment of water bodies with nutrients is called eutrophication - It can be due to natural factors such as erosion, rainwater runoff, etc. - It is a part of the natural aging process of water bodies - The rapid increase in nutrients available due to anthropogenic factors is called cultural eutrophication - *Sources of eutrophication:* - 1. Excessive use of fertilizers particularly nitrogenous, phosphorus - 2. Flood-irrigation method and agricultural runoff due to rainfall - 3. Discharge of sewage water into water bodies - 4. The release of industrial effluents - 5. Urban runoff - 6. Religious and cultural practices - *Impacts of eutrophication:* - 1. Increase in oxygen demand (both COD and BOD) - 2. Decrease in dissolved oxygen - 3. Large-scale growth of algae, water hyacinth, duckweeds, and various phytoplanktons - 4. No. of species in the water bodies decreases due to low levels of oxygen and sunlight - 5. Harmful algal blooms - Reasons for algal blooms include an increase in water temperature, global warming, thermal pollution, and excessive uncontrolled eutrophication - *The impact of harmful algal bloom includes:* - 1. Very low levels of dissolved oxygen - 2. Rapid decrease in other species and very low biodiversity - 3. Large-scale fish kill - 4. Discoloration of water with a foul smell making it unfit for use - 5. Certain toxic microorganisms survive like Clostridium Botulinum - 6. Increased pH level - 7. Gradual emergence of dead zones or hypoxic condition - *Controlling eutrophication:* - 1. Stop the runoff and divert rain waters - 2. Increase aeration and water movement - 3. Remove blooms manually - 4. Adding some artificial particles like clay which binds with algae and sinks - *==Bioaccumulation and Biomagnification==* - Bioaccumulation is the process through which the concentration of certain chemical substances increases continuously in the body tissues of an organism within a trophic level due to absorption from food and environment - Biomagnification or bio-amplification is the process by which certain chemical substances become more concentrated in the body tissues of organisms as one moves up the food chain - *Properties of compounds suitable for biomagnification:* - 1. They are long-lived or don't decompose easily - 2. They are persistent and cannot be disintegrated easily - 3. They are water-insoluble - A few examples include most heavy metals (e.g. lead, mercury, copper, cadmium, tin, etc.), cyanide compounds, and poly-nuclear aromatic hydrocarbons - Impacts the nervous system and immune system, increases cancer risk, impacts fertility, child growth, and failure of eggs due to the thinning of eggshells in birds ## AIR POLLUTION (3:29 PM) - It refers to the release of pollutants into the air that are detrimental to human health and the ecosystem - ==Primary Pollutants== - They are the air pollutants released directly from the source in the atmosphere - For example, sulfur dioxide, carbon dioxide, etc. - *==Secondary Pollutants==* - They are not released directly from the source but are formed due to the reaction of primary pollutants in the atmosphere - For example, smog, acid rain, etc. - | | | | | --- | --- | --- | | ***Pollutants*** | ***Sources*** | ***Harmful Impacts*** | | Carbon monoxide (CO) | Incomplete combustion of wood, biomass, coal, petroleum, etc. | Reduced oxygen levels in the blood (have an immediate impact on humans) | | Carbon dioxide (CO2) | Burning of any fossil fuel | Global warming, ocean acidification | | Oxides of sulfur, SOx (sulfur dioxide or SO2, hydrogen sulfide or H2S) | Thermal power plants, petroleum refineries, volcanic eruptions; decomposition releases H2S | Acid rain, respiratory issues, chlorosis (loss of chlorophyll pigment in plants) | | Oxides of nitrogen, NOx (nitric oxide NO, nitrous oxide N2O, nitrogen dioxide NO2) | Fossil fuels, fertilizers, denitrification, automobile exhausts | Acid rain, respiratory issues, eye irritation, reduced plant productivity | | Hydrocarbons (benzene and ethylene) | Burning of fuels | Respiratory issues, carcinogenic | | Particulate matter (PM) | Construction activities (demolition), stubble burning, industrial exhaust, automobile exhaust, waste burning, biomass burning, cement industries, spraying of chemicals in agricultural fields, textile and carpet industries, sandblasting | Respiratory diseases, headache, nausea, carcinogenic, reduced visibility resulting in the formation of smog | | Black carbon and brown carbon | Black carbon- High-temperature combustion in diesel engines, incomplete combustion in coal thermal power plant Brown carbon- burning of organic matter, cow dung | Greenhouse gases, they are particulate matter, impact the albedo of glaciers leading to faster melting | ## Topic for the next class: Air pollution (continued), Land degradation