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Environmental chemistry
- 1. 1 | P a g e Assignment Of General Chemistry Topic: Introduction And Scope Of Environmental Chemistry Submitted To: Sir Usman Khan Submitted By: Azam Khan Bs(H) Zoology 4th semester (Evening) University of Education Lahore Okara Campus.
- 2. 2 | P a g e Sr# Contents Page # 1 1.1 1.2 1.2.1 1.2.2 1.2.3 1.2.4 1.3 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 1.3.8 1.3.9 1.3.10 1.3.11 Environmental chemistry Introduction of environmental chemistry Environmental segments Biosphere Atmosphere Hydrosphere Lithosphere Environmental quality standards Tolerance Toxic substances Toxicology Pollution Contaminant Pollutant Receptor Sink Pathways of pollutant Pollution control Speciation 4 4 5 6 6 7 7 7 7 7 8 8 8 8 8 8 9 9 9
- 3. 3 | P a g e 1.3.12 1.4 1.4.1 1.4.2 1.4.3 1.4.4 1.5 1.6 1.7 Total pollution loading Environmental indicators Dissolved oxygen Chemical oxygen demand Biochemical oxygen demand Total dissolved solids Scope of environmental chemistry Need for public awareness References 9 10 10 10 10 11 11 13 14
- 4. 4 | P a g e 1-Environmental Chemistry Environment: “Environment literally means surrounding and everything that affect an organism during its lifetime is collectivelyknown as its environment.” OR ”Environment is sum total of water, air and land interrelationships among themselves and also with the human being, other living organisms and property “ Environmental Chemistry: Environmental science will be defined as the study of the earth, air, water, and living environments, and the effects of technology thereon 1.1Introduction Environmental Chemistry deals with the origins, transport, reactions, effects and fates of chemical species in the water, air, terrestrial and living environments. It overlaps with different branches of chemistry such as organic chemistry, analytical chemistry, physical chemistry, photochemistry, geochemistry and biological chemistry and also includes many widely different fields such as physics, life sciences, agricultural sciences, medical sciences, public health and sanitary engineering. Environmental chemistry is the study of chemical processes occurring in the environment which are impacted by humankind's activities. These impacts may be felt on a local scale, through the presence of urban air pollutants or toxic substances arising from a chemical waste site, or on a global scale,
- 5. 5 | P a g e through depletion of stratospheric ozone or global warming. Environmental Chemistry deals with the origins, transport, reactions, effects and fates of chemical species in the water, air, terrestrial and living environments. It overlaps with different branches of chemistry such as organic chemistry, analytical chemistry, physical chemistry, photochemistry, geochemistry and biological chemistry and also includes many widely different fields such as physics, life sciences, agricultural sciences, medical sciences, public health and sanitary engineering. Environmental chemistry is the study of chemical processes occurring in the environment which are impacted by humankind's activities. These impacts may be felt on a local scale, through the presence of urban air pollutants or toxic substances arising from a chemical waste site, or on a global scale, through depletion of stratospheric ozone or global warming. The focus in our courses and research activities is upon developing a fundamental understanding of the nature of these chemical processes, so that humankind's activities can be accurately evaluated. Environmental chemistry involves first understanding how the uncontaminated environment works, which chemicals in what concentrations are present naturally, and with what effects. Without this it would be impossible to accurately study the effects humans have on the environment through the release of chemicals.. Environmental chemists draw on a range of concepts from chemistry and various environmental sciences to assist in their study of what is happening to a chemical species in the environment. Important general concepts from chemistry include understanding chemical reactions and equations, solutions, units, sampling, and analytical techniques. 1.2-Environmental Segments: The environment consists of various segments such as atmosphere, hydrosphere, lithosphere and biosphere. Before explaining the Chemistry that
- 6. 6 | P a g e is taking place in these segments one by one, a brief out line about their importance will be discussed. 1.2.1-Biosphere The biosphere refers to the realm of living organisms and their interactions with the environment (VIZ: atmosphere, hydrosphere and lithosphere) The biosphere is very large and complex and is divided into smaller units called ecosystems. Plants, animals and microorganisms which live in a definite zone along with physical factors such as soil, water and air constitute an ecosystem. Within each ecosystems there are dynamic inter relationships between living forms and their physical environment These inter relationships manifest as natural cycles.(hydrologic cycle, oxygen cycle, nitrogen cycle, phosphorous cycle and sulphur cycle). The natural cycles operate in a balanced manner providing a continuous circulation of essential constituents necessary for life and this stabilizes and sustains the life processes on earth. 1.2.2-Atmosphere The following points highlight the vital role played by atmosphere in the survival of life in this planet. The atmosphere is the protective blanket of gases which is surrounding the earth. It protects the earth from the hostile environment of outer space. It absorbs IR radiations emitted by the sun and reemitted from the earth and thus controls the temperature of the earth.
- 7. 7 | P a g e It allows transmission of significant amounts of radiation only in the regions of 300 – 2500 nm (near UV, Visible, and near IR) and 0.01 – 40 meters (radio waves). i.e. it filters tissue damaging UV radiation below 300 nm. It acts as a source for CO2 for plant photosynthesis and O2 for respiration. It acts as a source for nitrogen for nitrogen fixing bacteria and ammonia producing plants. The atmosphere transports water from ocean to land. 1.2.3-Hydrosphere The hydrosphere is a collective term given to all different forms of water. It includes all types of water resources such as oceans, seas, rivers, lakes, streams, reservoirs, glaciers and ground waters. As can be seen, only 1% of the total water supply is available as fresh water in the form of rivers, lakes, streams and ground water for human consumption and other uses. The major problem with global water supply is it’s non-uniform distribution, since people in areas with low precipitation often consume more than people in regions with more rainfall. 1.2.4-Lithosphere The lithosphere consists of upper mantle and the crust. The crust is the earth’s outer skin that is accessible to human. The crust consists of rocks and soil of which the latter is the important part of lithosphere. 1.3-Environmental Quality Standards The maximum limit or concentration of the pollutant which is permitted in specific media such as air, water, soil etc. 1.3.1-Tolerance It refers to the ability of a organism to cope with changes in environment. It also refers to the safe level of any chemical applied to crops that will be used as food or seed.
- 8. 8 | P a g e 1.3.2-Toxic Substances Those substances which are harmful for an organism and cause death called toxic substances. 1.3.3-Toxicology The branch of chemistry which deals with toxic substances, mechanism of toxic substances by which they effect the organism. 1.3.4-Pollution This term is used to indicate about the substances introduce into the environment which has potentially harmful effects like air pollution, water pollution or soil pollution. 1.3.5-Contaminant Any material that is not present in nature but introduce by human activity and effect the environment is called contaminant. The effect of contaminant may be positive or may be negative. CO2 into environment. 1.3.6-Pollutant A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. Smoke in air. 1.3.7-Receptor Medium that is effected by the pollutant is called receptor. Human body is receptor for photo-chemical smog. 1.3.8-Sink Medium that is long lived effected by pollutant is called sink. Acid rain when fall on marble CaCO3 + H2SO4 Ca2SO4 + H2O + CO2
- 9. 9 | P a g e 1.3.9-Pathways of pollutant The mechanism by which pollutant get distributed into different segments of environment is called pathways of pollutant. Example: T.E.L exhaust PbCl2 + PbBr2 Soil Plants Tetra Ethyl Led Animals Humans 1.3.10-Pollution control By the help of methods or principles or equipment we can control the pollution this is known as pollution control. 1.3.11-Speciation Some compounds have various chemical forms about which we can predict that which form is harmful and which is not this is called speciation. CH3Hg and C2H5Hg, CH3Hg is more harmful than C2H5Hg. 1.3.12-Total Pollution Loading The aggregate mass of a specific pollutant discharge to the environment in a given time period is called total pollution loading. Aggregate mass is more important than the concentration of a pollutant as a basis of environmental protection.
- 10. 10 | P a g e 1.4-Environmental Indicators Chemical measures of water quality include Dissolved oxygen (DO) Chemical oxygen demand (COD) Biochemical oxygen demand (BOD) Total dissolved solids (TDS) 1.4.1-Dissolved oxygen (DO) The amount of oxygen dissolved in water is known as dissolved oxygen. Dissolve oxygen < 4-6 mg/L water will be polluted. Dissolve oxygen > 4-6 mg/L water will be. 1.4.2-Chemical Oxygen Demand (COD) The chemical oxygen demand (COD) test is commonly used to indirectly measure the amount of organic compounds in water. Most applications of COD determine the amount of organic pollutants found in surface water (e.g. lakes and rivers) or waste water, making COD a useful measure of water quality. It is expressed in milligrams per liter mg/L, which indicates the mass of oxygen consumed per liter of solution. 1.4.3-Biochemical Oxygen Demand (BOD) Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed (I. e., demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The BOD value is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days of incubation at 20 °C and is often used as a surrogate of the degree of organic pollution of water.
- 11. 11 | P a g e BOD can be used as a gauge of the effectiveness of waste water treatment plants. BOD is similar in function to COD, in that both measure the amount of organic compounds in water. However, COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biodegradable organic matter. 1.4.4-Total dissolved solids (TDS) Total dissolved solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a filter with two-micrometer (nominal size, or smaller) pores. Total dissolved solids are normally discussed only for freshwater systems, as salinity includes some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants. 2-Scope Of Environmental Chemistry Almost everything that happens in world around us could come under the general heading “Environmental Chemistry”. Chemical reactions of all kind occur continuously in the atmosphere, in oceans, lakes and rivers, in all living things and even underneath the earth’s crust. These reactions take place quite independently of human activities.
- 12. 12 | P a g e To understand environmental problems, we must have knowledge not only of what materials are being deliberately or inadvertently release into the environment, but also the process then they undergo. More than this we need to understand the general principles underlying these processes so that reasonable predictions can be made about the effects to be expected from new but related substances. We must also understand the principles that underline natural environmental processes to anticipate human interferences. Environmental chemistry emphasizes the chemical principles underlying environmental processes and the chemistry of anthropogenic components----- - the materials and changes that human have introduced. But to put these into context, some topics that are rather distant from reactions and equations need to be discussed. In addition, knowledge in biological, meteorological, oceanographic, and other fields is equally important to the overall understanding of the environment. Indeed, although convenient to segment topics for study purposes, Barry Commoner’s first law of the environment should always kept in mind: “Everything is related everything else.” Conservation of nature and natural resources. Conservation of biological diversity. Control of environmental pollution. Stabilization of human population and environment. Social issues in relation to development and environment. Development of non-polluting renewable energy system and providing new dimension to nation’s security. Environment belongs to all the living beings and thus is, important for all. Each and every body of whatever occupation he or she may have, is affected by environmental issues like global warming, depletion of ozone layer, dwindling forest, energy resources, loss of global biodiversity etc. Environment study deals with the analysis of the processes in water, air, land, soil and organisms which leads to pollute or degrade environment. It helps us for establishing standard, for safe, clean and healthy natural ecosystem.
- 13. 13 | P a g e It also deals with important issues like safe and clean drinking water, hygienic living conditions and clean and fresh air, fertility of land, healthy food and development. Sustainable environmental law, business administration, environmental protection, management and environmental engineering are immerging as new career opportunities for environment protection and managements. Heavy metal contamination of land by industry. These can then be transported into water bodies and be taken up by living organisms. Nutrients leaching from agricultural land into water courses, which can lead to algal blooms and eutrophication. Urban runoff of pollutants washing off impervious surfaces (roads, parking lots and rooftops) during rain storms. Typical pollutants include gasoline, motor oil and other hydrocarbon compounds, metals, nutrients and sediment (soil). Organometallic compounds 3-Need For Public Awareness With the ever increasing development by modern man, large scale degradation of natural resources have been occurred, the public has to be educated about the fact that if we are degrading our environment we are actually harming ourselves. To encourage meaningful public participation and environment, it is necessary to create awareness about environment pollution and related adverse effects. The United Nations conference on Environment and Development held in Rio-de-Janeiro, followed by Earth summit on sustainable Development have high-lighted the key issues of global environmental concern and have attracted the general public towards the deteriorating environment. Any Government at its own level can’t achieve the goal of environment conservation, until the public has a participatory role in it. Public participatory role is possible only when the public is awarded about the ecological and environmental issues. In short, if we want to manage on planet earth, we would have to make the entire population, environmentally educated. The objectives of environmental awareness should be: (a) Improving the quality of environment.
- 14. 14 | P a g e (b) Creating an awareness among people on environmental problems and conservation. (c) Creating such an atmosphere as people find themselves fit enough to participate in decision making process of environmental development programs. 4-References 1. Williams, Ian. Environmental Chemistry, A Modular Approach. Wiley. 2001. 2. American Meteorological Society. 3. J North Carolina State University. Department of Soil Science. 4. Global Resource Action Center for the Environment (GRACE). New York, NY. 5. Harrison, R.M (edited by). Understanding Our Environment, an Introduction to Environmental Chemistry and Pollution, Third Edition. Royal Society of Chemistry. 1 6. United States Environmental Protection Agency (EPA). Washington, DC. Document No. EPA 841-F-05-001. March 2005. 7. EPA. Document No. EPA 841-F-03-003. February 2003. 8. Sigel, A. (2010). Sigel, H.; Sigel, R.K.O., eds. Organometallics in Environment and Toxicology. Metal Ions in Life Sciences 7. Cambridge: RSC publishing. 9. Van Loon, Gary W.; Duffy, Stephen J. (2000). Environmental Chemistry. Oxford: p. 7. 10. Clescerl, Leonore S. (Editor), Greenberg, Arnold E.(Editor), Eaton, Andrew D. (Editor). Standard Methods for the Examination of Water and Wastewater (20th Ed.) American Public Health Association, Washington, DC. . This publication is also available on CD-ROM and online by subscription.