...What is Dissolved Oxygen? Dissolved Oxygen in a stream may vary from 0 mg/l to 18 mg/l. Readings above 18 mg/l are physically impossible. Dissolved oxygen gets into the water by diffusion from the atmosphere, aeration of the water as it tumbles over falls and rapids, and as a waste product of photosynthesis. What factors affect the DO level? Reduced DO levels in stream water may be because the water is too warm. The increased molecular activity of the warm water pushes the oxygen molecules out of the spaces between the moving water molecules. Decreased DO levels may also be indicative of too many bacteria and an excess amount of biological oxygen demand - BOD (untreated sewage, partially treated sewage, organic discharges, anoxic discharges) which use up DO. A third reason for decreased DO may be fertilizer runoff from farm fields and lawns. The same fertilizer which was meant to make land plants grow better now makes the aquatic plants do the same. If the weather becomes cloudy for several days, respiring plants will use much of the DO while failing to photosynthesize. When the increased numbers of aquatic plants eventually die, they support increasing amounts of bacteria which use large amounts of DO. Water Quality Index Chart- Based on Dissolved Oxygen Water Quality Index and BOD - Biological Oxygen Demand Students should be aware that plants, in general, only produce oxygen when light is available for photosynthesis. Rooted aquatic...
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...What is dissolved oxygen? Dissolved oxygen alludes to the level of free oxygen not bonded to any existing molecule in the water or other liquid substances. It is an important parameter in assessing water quality because of its influence on the organisms living within a body of water. In limnology (lakes studies), dissolved oxygen is a crucial factor second only to water itself. A dissolved oxygen level that is too high or too low can harm aquatic life and affect water quality. Non-compound oxygen, or free oxygen (O2), is oxygen that is not bonded to any other element. Dissolved oxygen is the existence of these free O2 molecules in the water. The molecule of oxygen bonded in a water molecule (H2O) is in a compound and does not count toward dissolved oxygen levels (Rivsbech et al., 1988). Dissolved oxygen from the atmosphere Dissolved oxygen goes into the water through the air or as a byproduct of a plant. From the air, oxygen can slowly diffuse across the water’s surface from the nearby atmosphere, or be assorted in rapidly through aeration, whether natural or man-made. Water aeration can be brought about by wind (creating...
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...DETERMINATION OF DISSOLVED OXYGEN Sl. No. Contents Preamble 10.1 Aim 10.2 Introduction 10.2.1 Environmental Significance 10.3 Principle 10.4 Materials Required 10.4.1 Apparatus Required 10.4.2 Chemicals Required 10.5 Sample Handling and Preservation 10.5.1 10.6 Precautions Procedure 10.6.1 Preparation of Reagents 10.6.2 Testing of Water Sample 10.7 Calculation 10.7.1 Table 10.7.2 Data Sheet 10.8 Interpretation of Results 10.9 Inference 10.10 Evaluation 10.0 EXPERIMENT ON DETERMINATION OF DISSOLVED OXYGEN PREAMBLE: “How to determine dissolved oxygen in Water and Wastewater”. Test procedure is in accordance to IS: 3025 (Part 38) - Reaffirmed 2003. In addition to our Indian Standard, we also discuss in brief regarding the procedure stated in (1) APHA Standard Methods for the Examination of Water and Wastewater - 20th Edition. Method 4500-O G. (2) Methods for Chemical Analysis of Water and Wastes, EPA-600/4-79-020, USEPA, Method 360.1. 10.1 AIM To determine dissolved oxygen (DO) in the given water sample with the stipulations as per IS: 3025 (Part 38) - Reaffirmed 2003. 10.2 INTRODUCTION Before performing this experiment, few questions may arise to the learners: 1. What is meant by Dissolved Oxygen (DO)? Is it oxygen in dissolved form? 2. Why we need to determine DO? 3. What are the methods available to determine DO? 4. Is it measured in natural water or wastewater? 5. Whether is it mandatory as per our codal provision to determine DO? The term Dissolved Oxygen...
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...DETERMINATION OF DISSOLVED OXYGEN IN WATER INTRODUCTION The dissolved oxygen content is an important index when considering its suitability for town supply. A good clean potable water will give dissolved oxygen value close to the theoretical value for the saturated solution of oxygen in water. When there is pollution from organic matter and other trade effluents, the dissolved oxygen is up in various biochemical oxidation processes and its is only slowly replaced through surface absorption. Such water will give a low dissolved oxygen content until oxidation is completed. Adequate dissolved oxygen is necessary for the life of fish and other aquatic organisms. The methods described below for the determination of oxygen in water is based on that devised by Winkler. When manganese hydroxide is precipitated in the water sample it is quickly oxidized to higher hydrated oxides (probably in the four valent state) by the dissolve oxygen. Iodine, equivalent to the dissolved oxygen content, is then liberated on acidification in the presence of iodine, and it may be titrated with standard thio‐sulphate. INTERFERENCES AND PRE – TREATMENT Most oxidising and reducing substances e.g dissolved organic substances, nitrite ions, higher‐valency manganese compounds, active chlorine, sulphide and sulphite ions, iron (II) and irons interfere. The influence of the dissolved organic substances can be excluded by conversion of the manganese hydroxides into oxygen‐sensitive carbonates by subsequent addition of 4 cm3 ...
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...EXPERIMENT 11: DETERMINATION OF DISSOLVED OXYGEN IN A WATER SAMPLE (WINKLER METHOD) INTRODUCTION In an alkaline solution, dissolved oxygen will oxidize manganese(II) to the trivalent state. 8OH-(aq) + 4Mn2+(aq) + 2H2O(l) －－＞ 4Mn(OH)3(s) The analysis is completed by titrating the iodine produced from potassium iodide by manganese(III) hydroxide. 2Mn(OH)3(s) + 2I-(aq) + 6 H+(aq) －－＞ 2Mn2+(aq) + I2(aq) + 6H2O(l) Sodium thiosulphate is used as the titrant. Success of the method is critically dependent upon the manner in which the sample is manipulated. At all stages, every method must be made to assure that oxygen is neither introduced to nor lost from the sample. Furthermore, the sample must be free of any solutes that will oxidize iodide or reduce iodine. Chemicals: Manganese(II) sulphate solution – prepared by dissolving 48 g of MnSO4.4H2O in water to five 100 cm3 solution; alkaline potassium iodide solution—prepared by dissolving 15 g of KI in about 25 cm3 of water, adding 66 cm3 of 50% NaOH, and diluting to 100 cm3; concentrated sulphuriv(VI) acid; 0.0125 M sodium thiosulphate solution; starch solution (freshly prepared). Apparatus: 250 cm3 volumetric flask, 250 cm3 conical flask, measuring cylinders, titration apparatus, magnetic stirrer Procedure: 1. Use a 250 cm3 volumetric flask to collect water sample. Fill the flask completely with water without trapping any air bubbles. 2. Add 1 cm3 of manganese(II) sulphate solution to the sample using a pipette...
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...DETERMINATION OF DISSOLVED OXYGEN BY WINKLER TITRATION 1. Background Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples. 2. Scope and field of application This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water) -1. The method is suitable for the assay of oceanic levels of oxygen in uncontaminated...
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...Topic : Determination of the amount of dissolved oxygen in a water sample by iodometry-the winkler’s method. Objective: To determine the amount of dissolved oxygen in a water sample by iodometry- the winkler’s method. Apparatus: volumetric pipette, 3 conical flask, burette, burette clamp, Pasteur pipette, reagent bottle, conical flask stopper, retord stand, white tile Materials: 2 ml manganese sulphate solution, 2 ml alkaline-iodine solution, 0.025M sodium thiosulphate solution, 2ml concentration sulphuric acid, starch solution Procedure 1. When sampling water, care must be taken to ensure that a good representative sample of the water to be analyzed is obtained. For most purposes, this includes attention to dissolved gases. Therefore, the water sample should be taken in a clean bottle which must be filled to overflowing and tightly sealed with stopper without introduction of air. If the water is sampled from a tap, it must be allowed to run for at least 5 minutes prior to sampling. For this purpose, you may collect the water into a 1 L reagent bottle fitted with a stopper. 2. The stopper is removed carefully from the conical flask and 2 mL of the manganese sulfate solution is added, discharging the reagent from the tip of a pipette put well below the water surface. Stopper is replaced. 3. Similarly, 2 mL of the alkaline-iodide solution is introduced. 4. The stopper is placed in the bottle, be sure that no air becomes entrapped. Some overflow may occur....
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...Santa Cruz, Trinidad | 4 | Site 4:Mt Hololo Rd Santa Cruz, Trinidad | 5 | Lab Reports | | Lab 1:Dissolved Oxygen and Biological Oxygen Demand | 7 | Lab 2:Total Suspended Solids | 10 | Lab 3:Total Dissolved Solids | 12 | Lab 4:Macro Invertebrate Fauna | 14 | Final Report | | Problem Statement, Objectives | 17 | Methods of Data Collection | 18 | Literature Review | 19 | Presentation and Analysis of Data | 20 | Discussion of Findings | 22 | Conclusions | 23 | Recommendations | 23 | Bibliography | 24 | Site Number: 1 Date: 28/11/13 Site: Reservoir Road, Santa Cruz, Trinidad (Control site – Furthest Upstream) Objective(s): To investigate a section of the river with little or no human impact to use as a control site. Activities: The class arrived at site 1 around 9:15am. Observations of the riverbed, the water itself, human influences and both flora and fauna were made. Also the temperature, depth, width, turbidity and rate of flow of the water were measured. Water samples for later analysis of total suspended solids, total dissolved solids and biological oxygen demand were collected. Upstream of the site a sample of water was collected to perform a dissolved oxygen test which was done at the site as seen in the dissolved oxygen lab report. After all the...
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...to use several pieces of equipment and several chemical kits in order to analyze the water sample. Each group may split up the tasks however it sees fit- however, each person in the group is expected to be able to complete any and all of the tests performed, with directions of course! Make sure that you answer the question on the last page of this handout as you work through the lab. You will need to share your answers with the others in your group. Test to Perform | Equipment or Kit Used | pH | Smart Colorimeter | Turbidity | Smart Colorimeter | Conductivity | Vernier LabQuest 2 and Conductivity probe | Ammonia Nitrogen | Smart Colorimeter | Nitrate Nitrogen | Smart Colorimeter | Phosphates | Smart Colorimeter | Dissolved Oxygen | Smart Colorimeter | Fecal Coliform | Coliscan EasyGel | To Begin: You have several small beakers and transfer pipettes on your table. You will need to transfer some of your water samples into these beakers, or other test tubes (found in the kits) in order to complete these tests. Do not put the pH meter or the conductivity probe directly into the large beaker of sample water- this could contaminate the entire sample, thus affecting the results of your other tests. The instructions for the Smart Colorimeter tests are in a pdf file on blackboard. You do not have to print out this document but it is there for you to refer to when needed. The directions needed for the specific tests we do in the lab will be there for you as...
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...Exercise 1: The Scientific Method Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since many living organisms require oxygen to survive, it is a necessary component of water systems such as streams, lakes, and rivers in order to support aquatic life. The dissolved oxygen is measured in units of parts per million (ppm). Examine the data in Table 4 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from and then answer the questions below. QUESTIONS 1. Make an observation – Based on the data in Table 4, describe the relationship between dissolved oxygen content and fish populations in the body of water. Discuss the pattern observed in the data set. Answer = as the Dissolved Oxygen goes up the greater the survival rate is for the fishes. The pattern for the Dissolved Oxygen goes up by two’s and the number of fish has a unique pattern when matched with the dissolved oxygen. Pattern (2, 4 ppm)…..the fishes decrease by one. (6, 8 ppm)……the fishes increase by 4 (10, 12 ppm)…the fishes increase by 3 (14, 16 ppm)….the fishes decreases by 4 18 ppm…..the fishes decreases by 5 2. Do background research – Utilizing at least one scholarly source, describe how variations in dissolved oxygen content in a body of water can affect fish populations. Answer = According to research the dissolved oxygen should be 5 mg or above in order...
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...Science Exercise 1: The Scientific Method Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since many living organisms require oxygen to survive, it is a necessary component of water systems such as streams, lakes, and rivers in order to support aquatic life. The dissolved oxygen is measured in units of parts per million (ppm). Examine the data in Table 4 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from and then answer the questions below. QUESTIONS 1. Make an observation – Based on the data in Table 4, describe the relationship between dissolved oxygen content and fish populations in the body of water. Discuss the pattern observed in the data set. Answer = quantitative because you can measure the dissolved oxygen and number of fish observed 2. Do background research – Utilizing at least one scholarly source, describe how variations in dissolved oxygen content in a body of water can affect fish populations. Answer = “Dissolved oxygen is necessary to many forms of life including fish, invertebrates, bacteria and plants. These organisms use oxygen in respiration, similar to organisms on land. Fish and crustaceans obtain oxygen for respiration through their gills, while plant life and phytoplankton require dissolved oxygen for respiration when there is no light for photosynthesis 4. The amount of dissolved oxygen needed varies from creature to creature...
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...Topic: Comparative analysis of portable water of Dhaka City Course: ENV 107 Section: 34 Semester: Summer 2016 Prepared by Istiaque Rahman ID: 1611345630 Prepared For Dr. Md. Tajuddin Sikder M. Sc. In Environmental Sciences (JU), Ph. D in Environmental Science (Hokkaido University, Japan) Department of Environmental Science and Management North South University, Dhaka, Bangladesh ABSTRACT Comparative examination of different samples of portable water sources of water in Dhaka city was carried out with a view to assess the different sources of water and determine the water quality of the different sources. The sources of water examined are MUM drinking water, NSU drinking water, NSU tap water, distilled water, Pepsi and waste water. Many parameters were taken in consideration to test the water including physical conditions such as smell, color, turbidity and chemical conditions such as pH, DO, E.coli, TDS and NaCl present in the samples. Finally, a comparative analysis was done to assess the water quality of each samples based on the results from the experiment done. INTRODUCTION Importance of Water: With two thirds of the earth's surface covered by water and the human body consisting of 75...
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...Date Lab 1 - Exercise 1: Data Interpretation Dissolved oxygen is oxygen that is trapped in a fluid, such as water. Since many living organism requires oxygen to survive, it is a necessary component of water systems such as streams, lakes and rivers in order to support aquatic life. The dissolved oxygen is measured in units of parts per million (ppm). Examine the data in Table 4 showing the amount of dissolved oxygen present and the number of fish observed in the body of water the sample was taken from; finally, answer the questions below. Questions 1. What patterns do you observe based on the information in Table 4? The fewer amounts of fish, the more oxygen there is in the water. They oxygen is measured in 2’s and the less fish there is the more oxygen there is. 2. Develop a hypothesis relating to the amount of dissolved oxygen measured in the water sample and the number of fish observed in the body of water? The more fish there is, the less amount of oxygen there is in the water. According to author’s Mckinsey& Chapman, “for fishes, dissolved oxygen is an abiotic factor that can limit habitat quality and affect survival, growth, and reproduction” (Mckinsey, D. & Chapman, L. 1998, pg. 211, para. 1). 3. What would your experimental approach be to test this hypothesis? I would add fish to the water and test the oxygen, and then remove fish and test the oxygen with each (ppm) in counts of 2 (ppm). Also, I would...
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...test to determinate the concentration of dissolved oxygen in water samples This test was originally developed by Lajos Winkler, an Hungarian analytical chemist, in 1888, modifying a preceding test. Winkler discovered a safer and more precise method of dissolved oxygen analysis thanks to an iodometric titration. https://medseastareso2012.wordpress.com/2012/06/23/winkler-method-by-walter/ Posted on June 23, 2012 by lormau An excess of manganese(II) salt, iodide (I−) and hydroxide (OH−) ions is added to a water sample causing a white precipitate of Mn(OH)2 to form. This precipitate is then oxidized by the dissolved oxygen in the water sample into a brown manganese precipitate. In the next step, a strong acid (either hydrochloric acid or sulfuric acid) is added to acidify the solution. The brown precipitate then converts the iodide ion (I−) to iodine. The amount of dissolved oxygen is directly proportional to the titration of iodine with a thiosulfate solution. https://en.wikipedia.org/wiki/Winkler_test_for_dissolved_oxygen Chiya Numako and Izumi Nakai (1995) The water sample used in this experiment is the tap water from UTAR and it has a ppm of 7.8 and average volume of titrant required for titration is 7.83 cm3 . While the standard data given in table 1 is when temperature at 20 c where the do of pure water is 9.2 and when the temperature increases by 10 c the do of water has dropped to 7.2 ,it indicates that the solubility of oxygen in water decreases with increasing temperature...
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...TECHNOLOGICAL INSTITTUTE OF THE PHILIPPINES 938 Aurora Blvd. Quezon City DISSOLVED OXYGEN INDICATOR ALARM IN FISH PONDS Members: Dulce, Rei Justin Faustino, John Benidict A. Serafica, Leopoldo Jr. Uru, Vincent C. Villaganas, Arbert A. Instructor: Engr. Kim KeryllTria Chapter 1 1.1Introduction and its Background The following students intend to have a promising research study contributing to the community creating a useful tool. This research project is an addition of what so called Microbial Fuel Cell a newly discovered technology on producing electricity using bacteria. In this Technology if an electrode is placed in waste water, bacteria automatically begin to grow on it. These bacteria are capable of transforming the organic compounds present in the water into electricity. This process purifies the waste water, which in and of itself is a useful application. But researchers from Wageningen UR and Wetsus, a water technology institute, who are working with each other as part of the Microbial Fuel Cell project, are more interested in generating electricity. They are testing organic materials which may act as catalysts on the process. They are also improving the design of the model to enable generating electricity on a larger scale. How a microbial fuel cell works A microbial fuel or biofuel cell requires: * Two electrodes * Bacteria such as those present in waste water or manure * A conducting wire with resistor (such as a light...
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