Environmental chemistry -Ocean pollution -A.pptx

Environmental chemistry -Ocean p

1. WATER QUALITY ASSESSMENT AND POLLUTION CONTROL WMA 318 Prof. O. Martins and Dr O.Z. Ojekunle Dept of Water Res. Magt . & Agromet UNAAB. Abeokuta. Ogun State Nigeria [email protected] https://slideplayer.com/slide/10954136/

2. COURSE CODE : WMA 318 COURSE TITLE : Water Quality Assessment and Pollution Control COURSE UNITS : 2 Units COURSE DURATION: 2 hours per week

3. COURSE DETAILS Course Cordinator : Prof. O. Martins B.Sc., M.Sc., PhD Email:[email protected] Office Location: Room B208, COLERM Other Lecturers: Dr. O.Z. Ojekunle B.Sc., M.Sc., PhD

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5. COURSE CONTENT Solvent properties of water; principles of physico -chemical analysis, major ionic components of natural water. Chemistry of natural waters, water quality requirements, standards for potable water, irrigation and livestock. Types of water, lithological control of surface and ground water. Water Pollution Studies: Sources, fate, pathways and effects of water pollution, Chemical, Mechanical and Biological methods of maintaining and improving water quality. Pre-requisite: CHM 202

6. COURSE REQUIREMENT This is a required course for students in the College of Environmental Resources Management. They are supposed to passed CHM 202 before registering for this course. As a school regulation, a minimum of 75% attendance is required of the students to enable him/her write the final examination

7. READING LIST Eidon D. Enger , Bradley F. Smith 2003. Environmental Science: A study of Interrelationships (Ninth Edition) McGraw-Hill International Edition Publication. William P. Cunningham, Mary Ann Cunningham 2008. Principles of Environmental Sciences, Inquiry and Applications (Fifth Edition) McGraw-Hill International Edition Publication. William P. Cunningham, Mary Ann Cunningham 2008. Environmental Sciences, A Global Concern (Eleventh Edition) McGraw-Hill International Edition Publication.

8. PROPERTIES OF WATER Water is a chemical compound of oxygen and hydrogen and in the gaseous state can be represented by the molecular formula H 2 O. The isotopes of hydrogen and three isotopes of oxygen exist in nature, and if these are taken into account, 33 varieties of water are possible. The physical properties of liquid water are unique in a number of respects, and these departure from what might be considered as normal for such a compound are of the greatest importance with respect to both the existence of life on earth and the operation of many geochemical processes. The boiling point and freezing point of water are both far higher than would be the theoretically expected, considering the low molecular weight of the compound, and the range of temperature over which water as a liquid is wider than might be expected. The reason for these and other departures from “ normal ” behaviour can be gained by more detailed consideration of the molecular structure of the compound.

9. MOLECULAR STRUCTURE OF WATER The spheres representing the ions coalesce to some extent, and the molecule might be thought of as a sphere having two rather prominent bubbles of “ blisters ” attached to it. Te bonds connecting the hydrogen ’ s to oxygen describe an angle of 105 o , so that the two hydrogen are relatively close together on one side of the molecule. Although this representation of the molecule is somewhat empirical it helps to explain some of the abnormal features of the behaviour of water. The molecule has dipolar properties because the positive charge associated with the hydrogen are connected on one side of the molecule, leaving a degree of negativity on the opposite side. Forces of attraction thus exist between hydrogens of one molecule and the oxygen bonds. They hold molecule together in a fixed pattern in the solid state. In contrast to the orderly arrangement of molecules in crystal of ice, the molecules of liquid water are in a chaotic condition of disorder. Hydrogen bonds still remain an important force but their arrangement is continually shifting The cohesive forces represented by the hydrogen bonds impact to liquid water is high heat of vaporization. The forces also tend to prevent the passage to electric currents and impart to the fluid its high dielectric constan t. The attraction between molecules of a liquid is shown at a liquid surface by the phenomenon called Surface tension. The surface of water is 75.6 dynes per centimeter at 0oC and 71.8 dynes per centimeter at 25 o C, which are very high values compared with the many other liquids

10. PROPERTIES OF WATER Chemical Constitution of Water 1 Ionic and Non Ionic Ionic Anion Cations 2 Major Anions Bicarbonate, Chloride, Sulphate Major Cations Sodium, Potassium, Calcium, Magnesium Non-Ionic SiO 2 , Dissolved gases, oily Substance, Synthetic detergent, etc

11. CHARACTERISTICS OF WATER Hardness Carbonate (Temporary) Hardness CaCO 3 Non Carbonate (Permanent) Hardness CaSO 4 Concentration of Hydrogen-ion, which are expressed in pH units. It is the — Log 10 H + Specific Electrical Conductance - Increases with temperature: values must therefore be related to the same temperature (2%) Colour Alkanity: Ability to neutralize acid; due to the presence of OH-, HCO 3 - , CO 3 2- , Acidity: Water with pH 4.5 is said to have acidity; caused by the presence of free mineral acids and carbonic acids Turbidity: Measure of transparency of water column; indirect method of measuring ability of suspended and colloidal materials to minimize penetration of light through water. Dissolved gasses: O 2 , N 2 , CO 2 , H 2 S, CH 4 , NH 3 , etc.

12. PHYSICAL CHEMICAL PARAMETER Since water is not found in its pure in nature, it is important to determine its combined physical, chemical and biological characteristics. This is done through monitoring of water for its quality. Physical chemical parameter analyzed in natural environments; Atmosphere (rainfall), hydrosphere (river, lakes, and oceans) and Lithosphere (Groundwater) are similar-

13. PHYSICAL CHEMICAL PARAMETER (Cont) Temperature: Measurement is relevant For Aquatic life Control of waste treatment plants Cooling purposes for industries Calculation of solubility of dissolved gases Identification of water source Agriculture Irrigation Domestic uses (Drinking, bathing) Instrument of measurement is thermometer pH: Controlled by CO 2 /HCO 3 - /CO 3 2- Equilibria in natural water. Its values lie between 4.5 and 8.5. It is important Chemical and biological properties of liquid Analytical work Measurement is done in the field. Most common method of determination is the electrometric method, involving a pH-meter. It is important to calibrate the meter with standard pH buffer solutions

14. PHYSICAL CHEMICAL PARAMETER (Cont) Dissolved Oxygen: Water in contact with the atmosphere has measurable dissolved oxygen concentration. It values depends on Partial pressure of O 2 in the gaseous phase Temperature of the water Concentration of salt in the water (the higher the salt content in water, the lower the concentration of dissolved oxygen and the other gases). Measurement is important in Evaluation of surface water quality Waste-treatment processes control Corrosivity of water Septicity Photosynthetic activity of natural water

15. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS Temperature: Temperature affects the density of water, the solubility of constituents (Such as oxygen in water), pH, Specific conductance, the rate of chemical reactions, and biological activity of water . Continuous water quality sensor measure temperature with thermistor, which is a semiconductor having resistance that changes with temperature. Thermistor are reliable, accurate, and durable temperature sensors that require little maintenance and are relative inexpensive. The preferred water-temperature scale for most scientific work ids the Celcius scale. measure temperature to plus or minus 0.1 degree celcius ( o C)

16. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont) Specific Conductance: Electrical conductivity is a measure of the capacity of water to conduct an electrical current and is a function of the types and quantities of dissolved substance in water. As concentration of dissolved ions increase, conductivity of the water increases. Specific conductance is the conductivity expressed in units of Microsiemen per centimeter at 25 o C. Specific conductance are a good surrogate for total dissolved solids and total ions concentrations, but there is no universal linear relation between total dissolved solids and specific conductance. Specific conductance sensors are of 2 types: contact sensors with electrodes and sensor without electrodes.

17. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont) Salinity: Although Salinity is not measured directly, some sondes include the capability of calculating and recording salinity based on conductivity measurement. Conductivity has long been a tool of estimating the amount of chloride, a principle component of salinity in water. Salinity is commonly reported using the Practical Salinity Scale (PSS), a scale developed to a standard potassium-chloride solution and based on conductivity, temperature and barometric pressure measurement. Before developing the PSS, salinity was reported in part per thousand/million. Salinity expressed in the PSS is a dimensionless value, although by convection, it is reported as practical salinity unit.

18. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont) Dissolved Oxygen: Sources of DO in surface waters are primarily atmospheric reaeration and photosynthetic activity of aquatic plants. DO is an important factor in chemical reactions in water and in the survival of aquatic organisms. In surface water, DO concentration typically range from 2-10mg/l. DO saturation decreases as water temperature increases, and DO saturation increases with increased atmospheric pressure. Occasion of super saturation (greater than 100 percent DO saturation) often are related to excess photosynthetic production of oxygen by aquatic plants as a result of nutrient (nitrogen and Phosphorus) enrichment, sunlight and warm water temperature. DO may be depleted in inorganic oxidation reaction or by biological and chemical processes that consume dissolved, suspended or precipitated organic matter. The DO Solubility in saline environments is dependent on salinity as well as temperature and barometric pressure . DO in water that have specific conductance values of greater than 2000 microsiemens/centimeter should be corrected for salinity. The newest technology for measuring DO is the Luminescent sensor that is based on dynamic fluorescence quenching.

19. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont) pH: The pH of aqueous solution is controlled by the interrelated chemical reactions that produce or consume hydrogen ions. The pH of a solution is a measure of the effective hydrogen-ion concentration. More specifically, pH is a measure that represents the negative base-10 logarithm of hydrogen-ion activity of a solution, in moles per liter. Solutions having a pH below 7 are described as acidic, and solutions with pH greater than 7 are described as basic or alkaline. Dissolved gases such as carbon dioxide, hydrogen sulphide and ammonia, apparently affect pH. Dagasification (for example, loss of carbon dioxide) or precipitation of a solid phase (for example, calcium carbonate) and other chemical, physical, and biological reactions may cause the pH of a water sample to change appreciably soon after sample collection . The electrometric pH-measurement method, using a hydrogen-ion electrode, commonly is used in continuous water-quality pH sensors. A correctly calibrated pH sensor can accurately measure pH to -+ 0.2 pH units; however, the sensor can be stretched, broken or fouled easily. If the streamflow rates are high, the accuracy of the pH measurement can be affected by streaming-potential effects.

20. MEASUREMENT & RELATIONSHIP OF PHYSICAL CHEMICAL PARAMETERS (Cont) Turbidity: Turbidity is defined as an expression of the optical properties of a sample that cause light rays to be scattered and absorbed, rather than transmitted in straight lines through a sample. ASTM further describe turbidity as the presence of suspended and dissolved matter, such as clay, silt, finely divided organic matter, plankton, other microscopic organisms, organic acids, and dyes. Implicit in this definition is the fact that colour, either of dissolved materials or of particles suspended in the water also can affect turbidity. Turbidity sensors operate differently from those for temperature, specific conductance, DO, and pH, which convert electrical potentials into the measurement of constituent of interest. Submersible turbidity sensors typically direct a light beam from light-emitting diode into water sample and measure the light that scatters or is absorbed by suspended particles in water. Most commercially available sensors report data in Nephelometric Turbidity Units (NTU)/ with a sensor range of 0-1000 and an accuracy of -+5 percent or 2NTU, whichever is greater.

21. WATER QUALITY ASSESSMENT AND POLLUTION CONTROL WMA 318 PART 2

22. Note For any water body to function adequately in satisfying the desired use, it must have corresponding degree of purity. Drinking water should be of highest purity. As the magnitude of demand for water is fast approaching the available supply, the concept of management of the quality of water is becoming as important as its quantity .

23. Contaminant Are physical, chemical, biological or radiological substances found as unwanted residue in or on a substance. Pathogens: Are micro organisms that can cause diseases e.g bacteria Metals (Metals that are harmful in relatively small amounts are labeled toxic)

24. Disease caused by contaminants Salmonella Typhi Typhoid fever Vibro Cholera Cholera Entameoba histolytica Amoeba Dysentery Escherichia Coli (E. Coli) Gastroenterits Enterovirus Polio Hepatitis Infestious Hepatitis Heavy Metal Cancer

25. Water Purification Process Abstraction: Abstraction involves pumping and transportation of raw water, a process with high rate of electrical energy consumption. It occurs at the intake. Screening: Is defined as the process whereby relatively large and suspended debris is removed from the water before it enters the plant. Aeration: Aeration (Air Stripping) is a physical treatment process whereby air is thoroughly mixed with water to removed dissolved gasses and odour. Coagulation: Addition of chemical to remove suspended solids. Flocculation: A chemical flocculent, such as aluminium sulphate, is mixed rapidly with the water to remove mud. Sedimentation: Also known as clarification- is the gravity-induced removal of particles. Filtration: Involves the removal of suspended particles from water by passing it through a layer or bed of a porous granular material e.g sand. The filter water the passed through nozzles, the nozzles and sand in the filter beds must be cleaned periodically (This is known as back washing). Chlorination: After filtration, the water looks much more cleaner than it was in the dam or river but it may not yet be healthy to drink because it may contain unseen micro-organism (bacteria) that are dangerous to the human body and can serious illness (such as diahorrea) 4.5 liters – 1 Gallon. 1 Liter – 100cl. 1 m3 – 5 drums or 200 liter volume.

26. WATER QUALITY OBJECTIVES AND REQUIREMENT A major advantage of the water quality objectives approach to water resources management is that it focuses on solving problems caused by conflicts between the various demands placed on water resources, particularly in relation to their ability to assimilate pollution. The water quality objectives approach is sensitive not just to the effects of an individual discharge, but to the combined effects of the whole range of different discharges into a water body. It enables an overall limit on levels of contaminants within a water body to be set according to the required uses of the water.

27. WQ Criteria For some other water quality variables, such as dissolved oxygen, water quality criteria are set at the minimum acceptable concentration to ensure the maintenance of biological functions.

28. Examples of the development of national water quality criteria and guidelines in Nigeria In Nigeria, the Federal Environmental Protection Agency (FEPA) issued, in 1988, a specific decree to protect, to restore and to preserve the ecosystem of the Nigerian environment. The decree also empowered the agency to set water quality standards to protect public health and to enhance the quality of waters

29. Background Information FEPA approached this task by reviewing water quality guidelines and standards from developed and developing countries as well as from international organisations and, subsequently, by comparing them with data available on Nigeria's own water quality. The standards considered included those of Australia, Brazil, Canada, India, Tanzania, the United States and the World Health Organization (WHO). These sets of data were harmonised and used to generate the Interim National Water Quality Guidelines and Standards for Nigeria

30. Background Information (Cont) These sets of data were harmonised and used to generate the Interim National Water Quality Guidelines and Standards for Nigeria. These address drinking water, recreational use of water, freshwater aquatic life, agricultural (irrigation and livestock watering) and industrial water uses. The guidelines are expected to become the maximum allowable limits for inland surface waters and groundwaters, as well as for non-tidal coastal waters. They also apply to Nigeria's transboundary watercourses, the rivers Niger, Benue and Cross River, which are major sources of water supply in the country.

31. THE NATIONAL ENVIRONMENTAL STANDARDS AND REGULATIONS ENFORCEMENT AGENCY (NESREA) Prior to the dumping of toxic waste in Koko village, in Delta State, in 1987, Nigeria was ill equipped to manage serious environmental crisis, as there were no institutional arrangement or mechanisms for environmental protection and enforcement of environmental laws and regulations in the country. Arising from the Koko toxic episode, the Federal Government promulgated the Harmful Waste Decree 42 of 1988, which facilitated the establishment of the Federal Environmental Protection Agency (FEPA) through Decree 58 of 1988 and 59 (amended) of 1992. FEPA was then charged with the overall responsibility of environmental management and protection. It is on record that by the establishment of FEPA, Nigeria became the first in African country to establish a national institutional mechanism fir environmental protection.

32. NESREA (Cont) In the wisdom of Government, FEPA and other relevant Departments in other Ministries were merged to form the Federal ministry of Environment in 1999, but without an appropriate enabling law on enforcement issues. This situation created a vacuum in the effective enforcement of environmental law standards and regulations in the country. To address this lapse, the Federal Government in line with Section 20 of the 1999 constitution of the Federal Republic of Nigeria, established the National Environmental Standard and Regulations Enforcement Agency (NESREA), as a parastatal of the federal Ministry of Environment. By the NESREA Act 2007, the Federal Environmental Protection Agency Act Cap F10 LFN 2004 has been repealed (NESREA 2007).

33. Table 1 Definition Related to Water Quality and Pollution Control

34. Water quality criteria for individual use categories Water quality criteria have been widely established for a number of traditional water quality variables such as pH, dissolved oxygen, biochemical oxygen demand for periods of five or seven days (BOD 5 and BOD 7 ), chemical oxygen demand (COD) and nutrients. Such criteria guide decision makers, especially in countries with rivers affected by severe organic pollution, in the establishment of control strategies to decrease the potential for oxygen depletion and the resultant low BOD and COD levels.

35. Development of criteria for Aquatic DO Numerous studies have confirmed that a pH range of 6.5 to 9 is most appropriate for the maintenance of fish communities. Low concentrations of dissolved oxygen, when combined with the presence of toxic substances may lead to stress responses in aquatic ecosystems because the toxicity of certain elements, such as zinc, lead and copper, is increased by low concentrations of dissolved oxygen. High water temperature also increases the adverse effects on biota associated with low concentrations of dissolved oxygen.