Reverse osmosis (desalination) is a process of purifying water using a semi-permeable membrane. In this process, a form of counter pressure is applied to overcome the osmotic pressure that is determined by chemical potential and a thermodynamic constraint. The concentrations of seawater and brackish water differ considerably; hence, there is a distinction involving the concentrate acquired from seawater desalination plants and brackish water desalination plants (Bergman, 2007).
Seawater reverse osmosis systems are meant to eradicate huge quantities of salts and other mineral deposits from seawater. Seawater has a high salinity rate because it is found in areas that experience high evaporation rates mostly in the latitudes of north and south. Therefore, seawater reverse osmosis entails applying high pressure to the water that is contaminated forcing it to pass through semi-porous membranes, which prevents salts and other organics from passing. The main function of the membrane is to remove dissolved solids in the solution with an aim of separating the feed water from purified water. Seawater desalination utilizes minimal energy exploitation corresponding to the osmotic pressure multiplied by the volume of desalinated water. This energy is general and efficient to all desalination technologies that are used in water purification (Cipollina, Micale, & Rizzuti, 2007).
Brackish water contains a higher amount of salinity than fresh, but not as much as sea or ocean water. Moreover, brackish water is obtained through a mixture of fresh water and seawater, at a point where rivers run into the ocean. The brackish water reverse osmosis is a technique that removes organic wastes and impurities from water. This process is also capable of removing constituents that have a higher molecular mass. For instance, heavy metals and organic compounds are also found in brackish water, and they have a great impact on the concentration of the water. Therefore, hydraulic pressure is used to overcome a nourish solution’s osmotic pressure and induce the distribution of pure water through a semi-permeable membrane. In this case, this process is applicable in foodstuff and drink industries, potable drinking water, hospitals, farming and resorts, water bottling and ice manufacture, pharmaceuticals (Greenlee, Lawler, & Freeman, 2009).
Before water starts to undergo the above treatments, there is a stage of the pretreatment process, which is aimed at reducing fouling that may cause reduction of the water flux; hence, minimizing the water recovery in the process. Pretreatment also minimizes hydrolysis and oxidation, which may result from reactions between metals and chemicals found in the feed water. Some of the processes that are involved in pretreatment include acid treatment, cartridge filtration, dechlorination, and coagulation. On the other hand, chemicals used during these processes include chlorine, sulphuric acid, sodium bisulphate, and calcium hypochlorite (Committee on Advancing Desalination Technology, 2008). In the desalination process, high concentrations of brine composed of large quantities of chemicals are discharged at the end. There are other discharges, which are obtained in the process of pretreated water that has undergone treatment, but not obtained by the required quality to pass through the membrane. The other discharge is permeating. It has not yet qualified as a final product; in fact, the permeating process has a lower salinity, and it contains very few harmful chemicals (Mauguin & Corsin, 2005).
References
Bergman, R. (2007). American Water Works Association Denver Reverse Osmosis and Naofiltration. Denver, CO: American Water Works Association.
Cipollina, A., Micale, G. & Rizzuti, L. (2007). Seawater Desalination. Conventional and Renewable Energy Processes. New York: Springer.
Committee on Advancing Desalination Technology. (2008). Desalination: A National Perspective. Washington, D.C.: The National Academies Press
Greenlee, L., Lawler, D. & Freeman, B. (2009). Reverse osmosis Desalination: Water sources, technology, and today’s challenges. Water Research. 2317-2348. Web.
Mauguin, G. & Corsin, P. (2005). Concentrate and other waste disposals from SWRO Plants: characterization and reduction of their environmental impact. Mauguin-SWRO rejects-Italy-may 05, 182(1–3), 355–364. Web.
Although medicine is generally seen as a field of human knowledge existing irrespective of social and political influences, the reality is that all spheres of life are closely interconnected. While diseases themselves are not political, the causative factors as well as approaches to solving medical problems are often directly influenced by the government. Medical anthropology studies diseases and illnesses within the context of political, social and economic conditions that exacerbate or cause such issues. Exploration of medical problems associated with water contamination will provide the most striking example of the essence of medical anthropology.
Few natural resources are as essential for survival and as commonly underestimated as water is. It is used to satisfy a number of basic human needs, ranging from preventing dehydration to hygiene and sanitation. Regular intake of clean water helps maintain physical health, ensures effective digestion, directly influences cellular functions and blood pressure. Meanwhile, the absence of water is a threat to health and well-being, which may cause a plethora of diseases. Finally, protracted deprivation of water can lead to death within the course of several days. It should be evident that access to clean water is an important constituent of individual and collective health and survival.
It should also not be surprising that water forms the backbone of economy and politics. Water is the reason why the majority of cities were built on rivers. It is essential in feeding communities, crop cultivation and functioning of irrigation systems. Water provides an effective means of transportation necessary for flourishing of commerce. Rivers and lakes are geographical barriers important for safety and security. Overall, there are many anthropological explanations for the significance of water for mankind. Control of water is also directly related to power and politics. The role of water is so important that any economic or political disturbance can result in the worsening health problems of the population.
Even though most of the media do not communicate it, the current world is also experiencing a serious water crisis. Wells and Whiteford quote the World Health Organization: “an estimated 2 billion people drink water that is contaminated and an estimated 4.5 billion use sanitation systems that do not protect their health” (160). The absence of water is a cause of deaths of hundreds thousands of lives, including children. However, the most important aspect about this observation is that the majority of such cases transpire in low-income countries. These governments cannot provide for the basic needs of their populations, thus worsening the crisis.
The most recent and evident example of the failure in disease management due to the absence of water is COVID. Probably, the first piece of advice regarding this infection each person hears is the necessity to wash hands. Exposure to soap and clean water removes germs from the skin. Regular handwashing reduces the risk of contracting an airborne virus. However, the necessary precursor to effective hygiene is the availability of clean water. The more challenged in terms of water resources a community is, the more likely it is to experience higher disease transmission frequency. It is reasonable to suggest that had more poor countries not experienced water scarcity, the impact of the pandemic would not have been as devastating.
However, as alarming as disease outbreaks are, they are not the only medical consequence of water scarcity. Actually, most of the health complications caused by water shortage are not reported and publicly known. The reason for this is that the most water-challenged community do not receive sufficient media attention. Most of the healthcare content online covers widespread issues in developed world. Meanwhile, the resource-challenged communities are often forgotten. As a result, people in such communities cannot protect themselves from pathogens or satisfy the basic human need for drinking.
The most evident example of such a community is Indigenous peoples in Canada. Duignan, Moffat, and Martin-Hill point out the drastic health disparities between mainstream Canada society and its indigenous communities (50). Most Canadians have adequate healthcare and experience no water shortage. In comparison, indigenous communities have contaminants in water sources such as E. coli, chromium, aluminum, manganese, arsenic, mercury, and uranium (Duignan, Moffat and Martin-Hill 53). As a consequence, indigenous Canadians are restricted in the choice of water sources and has worse health outcomes than mainstream Canadians, who are not aware of the formers’ issues.
In conclusion, water shortage is a serious factor negatively impacting the quality of life and overall health resilience. Water control determines the distribution of power in society and economy. The less the government is able to provide for the water needs of the population, the worse the overall health outcomes are. The COVID pandemic was especially devastating in water-challenged communities. Meanwhile, indigenous communities continue to experience the effects of complex inequality, with the indigenous peoples in Canada suffering from health disparities and water shortage in particular. Ultimately, medical anthropology showcases the relationship between socio-economic and political conditions and health outcomes using water shortage as the causative factor determined by political context.
Works Cited
Duignan, Sarah, Tina Moffat, and Dawn Martin-Hill. “Using Boundary Objects to Co-Create Community Health and Water Knowledge with Community-Based Medical Anthropology and Indigenous Knowledge.” Engaged Scholar Journal: Community-Engaged Research, Teaching and Learning, vol. 6, no. 1, 2020, pp. 49-76.
Wells, E. Christian, and Linda M. Whiteford. “The Medical Anthropology of Water and Sanitation.” A Companion to Medical Anthropology, edited by César E. Abadía-Barrero, Merrill Singer and Pamela I. Erickson, Wiley, 2022, pp. 160-179.
Metal ions in solution can be determined by titration with complex forming ions. EDTA is one of the most popular complexing agents that is suitable for this purpose because it complexes with multiple metal ions. EDTA forms stable complexes with many metals anions. The bonding is through the carboxyl oxygens and the two nitrogens.
Introduction
Titrometry is one of the techniques that chemical analysts use to determine the concentration of metal ions in mineral water. A complexing agent is necessary to facilitate accurate estimation of metal ions concentration in water. EDTA is the most popular complexing agent scientists use in the titrometry of metal anions in mineral water.
Complexes form from the interaction of metal ions with tetrabasic ions from an acid. The nickel chemical structure includes an oxygen atom from a molecule of water that substitutes an oxygen atom from EDTA at the sixth position of the structure. This chemical reaction can be represented in the equation below (Gordon & Lim 2012):
Mn+ + Y4- ↔ MYn-4
Y4- represents the tetrabasic anion of EDTA.
Titration using EDTA involves indicators that are specific or selective. These indicators form complexes with dissolved metal ions, but EDTA complexes with metal anions preferentially, liberating the indicator at the stoichiometric point. Both the complex and the indicator are colored. Thus, the liberation of indicator causes a color change that is unique to the metal anion (Gordon & Lim 2012). A buffer is necessary to provide suitable pH for the complexing of EDTA with metal. Masking agents may be added to the mixture in the flask to avert interference from extraneous metal anions.
Structure of EDTA.
Method
A 0.01 M EDTA solution was prepared for the titrometry. 25.00ml of aliquot was measured using a pipette into the Erlenmeyer flask. A 2 mL of ammonia, buffered at pH 10, were added into the Erlenmeyer flask before adding 0.2 g of ascorbic acid, and a few drops of Eriochrome Black T Indicator. The water sample with Eriochrome Black T indicator was titrated with the standard solution of EDTA until the color of the mixture in the flask turned from wine red to clear blue. The addition of titrant was done slowly because the change of color towards the endpoint is usually steady. The titration was repeated thrice to obtain three concordant results.
Results
First reading of titration = 17.5
Second reading of titration = 17.4
Third reading of titration = 17.5
Titration
1st
2nd
3rd
Amount of titrant (ml)
17.5
17.4
17.5
Concentration of Mg2+ = 52.0
M (EDTA) = 0.01 M
V (EDTA) = 17.18
n = C*V
n = 0.0100*00175 = 0.175
Calculations
Discussion
Since Eriochrome Black T acts as an acid-base indicator, the titration should be performed at a stable pH. Eriochrome Black T can occur in three different forms as shown below depending on the pH of the environment.
This complex is wine red in colour and less steady compared to Mg (EDTA)2 complex. In the event of titration of a solution containing Mg ions, the EDTA complexes with free Mg2+ first before reacting with MgIn– complex to liberate the indicator and yield blue color.
These are the results I have expected as there can be more than one type of metal ion in mineral water. I used more EDTA because of extraneous metal ions that the titrant formed complexes with. Thus, more EDTA was necessary to reach the endpoint.
Because the hardness of mineral water differs based on the source, the volume of sample water for every titration ought to be determined following the first experiment with a choice volume of the water sample. An experimenter must dilute the standard 0.01 M EDTA solution for use with extremely soft water. Conversely, little water samples or higher molar EDTA solutions are used for very hard water (Blackman, Bottle, Schmid, Mocerino & Wille 2012). Often, the test water contains sufficient Mg ions to facilitate direct titration.
Ions of aluminum, copper, nickel and iron if they are present, even in negligible concentrations, complex with the indicator obscuring the sharpness of the color change at the endpoint. Consequently, the experimenter should add KCN to eradicate all the extraneous metal ions.
The experimenter cannot titrate Ca2+ by itself to the endpoint of the Eriochrome Black T, because the association constant for a calcium-Eriochrome T complex is negligible. The titration of a metal ion is non-selective. The success of a non-selective titration of a metal ion is usually facilitated by the addition of a determined amount of Mg ions if the association constant of the other metal ion with EDTA exceeds that of Mg2+ with EDTA. In addition, the association constant for the metal-indicator complex must be low for the mentioned situation to take place (Housecroft & Constable 2010).
Among all metal ions for which the titration with EDTA applies, a Magnesium ion is apparently the most insensitive to solutes that are capable of forming complexes with EDTA. Thus, experimenters are able to perform all magnesium titrations with a single indicator.
Conclusion
In the most popular way of titrating magnesium with EDTA (Schwarzenback’s technique), Eriochrome Black T is the most popular indicator of choice. It allows the experimenter to adjust the medium of titration to pH 10 by adding ammonia or ammonium chloride buffer. Adding 0.2 g of ascorbic acid helps remove oxygen from the titrate to avert oxidation of the indicator by air. The color of titrating is red at pH 10 in the presence of Mg2+ before titration, because of magnesium-Eriochrome Black T complex. Thereafter, it turns magenta because magnesium-EDTA complex immediately before the reaction reaches the stoichiometric point. After the endpoint, it turns blue with titration of excess EDTA.
References
Blackman, A, Bottle, S, Schmid, S, Mocerino, M & Willie, U. 2012. Chemistry, John Wiley & Sons Australia, Milton Qld. Chapter 13.
Gordon, J & Lim, K 2012, SLE235 Chemical Systems Laboratory Manual, Deakin University of Australia, School of Life and Environmental Sciences, Faculty of Science & Technology:
Housecroft, C & Constable, E 2010, Chemistry, Prentice Hall. Chapter 23.
For Davis Water Suppliers to meet the requirements of the Water Regulatory Bodies, they need to install Water Fluoridating Systems. Accordingly, the Water Fluoridating Plant design is to help them meet the requirement of the laws regulating water suppliers at an efficient cost. Additionally, the system meets the minimum requirements of fluoride chemical prescription under section 4 of the Water Fluoridation Regulation. That is, it can use any of the chemicals suitable for fluoridating water including Sodium fluorosilicate, Fluorosilicic acid, and sodium fluoride. Whereby, the system does not allow the amount of fluoride to exceed 1.5mg/l.
There are various roles that the system is expected to play. For instance, it must have an instrument measuring the immediate fluoride levels in the water, calculate the real-time water flow rates, fluoride dose rate, and analyze fluoride concentration. Additionally, it must have both manual and automatic shut down available at all times for closing the dosing in cases of emergency (Queensland Government 4).
To meet the high regulations demanded, the system operations designs are fully automated, the dosing equipment interlocks and it has a flow meter to measure the rate of water flows. The fact that the system interlocks, allows the dosing system to lock itself in case one part of the system fails. On the other hand, the flow meter provides the rates of water flow to the dosing facility, which interprets the amount of fluoride needed in the water. It is from the flow rates, the dosing facility releases fluoride. In case the flow meter malfunctions, the system interlocks and prevents the release of wrong volumes of fluoride.
Another thing helping to feed the dosing facility with water flow information is the flow switch. When the flow switch is off, the dosing system will never release fluoride. Hence, the dosing facility releases fluoride when it detects the flow switch is on. However, there occurs inconsistency between the flow switch and flow meter. As a result, the control system is available to ensure the dosing facility switches off when these differences occur. Nevertheless, the whole system may fail in its regulations and as a result, there is an alarm system to notify persons attending them when the fluoride levels exceed 1.3ml/l.
Similarly, the tanks holding chemicals such as sodium fluoride and fluorosilicic acid have online level indicators monitoring them and the graduated scale is readable at ease. Consequently, the tanks refill before being exhausted.
Operational Feature
Fluorosilicic acid is unloaded at an unloading bay where spills are contained easily and pumped using 3-phase power pumps into fluorosilicic storage tanks. Each fluorosilicic tank for every borehole holds 10, 000 liters, and radar installation help to prevent spills. Then, from the fluorosilicic tank, another pump transfers the chemicals slowly to the second tank with lower capacity but fills automatically. Load cells monitor the second tank to maintain the recommended volume. Additionally, the pump feeding the second tank is fitted with an alarm and safety pipe to deliver chemicals back to the first tank in times of malfunctions (Maffescioni 17).
From there, the chemical passes through the control room. In the control room, it provides access points for starting or stopping all automated operations. It can also stop any flow of chemical and already treated water. Then, the pipe supplying chemicals reaches the dosing pumps where water is treated. After the water is treated, a sample of water is taken to the online analyzer positioned in the laboratory, and the remaining water is checked through a local control system, which is fitted with a checking alarm. The alarm makes a notification when there is a persistent 1.3ml/g level of fluoride (Maffescioni 18).
In conclusion, from the above, the below diagram illustrates the operational feature of the fluoridation system to be used when adding fluoride to each wells water serving Davis company.
References
Queensland Government. Queensland Health-Population Health Queensland Investigators Report. Water Fluoridation Incident-North Pipe Water Treatment Plant. 2009.Web.
Extensive techniques of molecular spectroscopy allow for combined analyses of the physical and chemical properties of substances. Among a large number of techniques, special attention should be paid to those that qualitatively describe the phenomena of luminescence. In general, luminescence is understood as the glow of substances not accompanied by heat production but initiated by the absorption of photons.
The nature of such luminescence can be due to various intramolecular mechanisms, one of which is the transition of an excited molecule from the lowest singlet vibrational level to the ground state. Broadly speaking, any multiplets transitions can be safely called fluorescence, whether in the singlet or triplet state. Consequently, the intensity of fluorescence emitted by matter is described by Equation 1. Considering the width b, the molar absorptivity ε, and the incident radiation power P0 as constant quantities, it is appropriate to light equation 1 to equation 2.
Then it becomes evident that there is a linear dependence with the coefficient K between the concentration of the substance and the intensity of the emission registered by the spectrofluorometer. This statement was used for this laboratory work, in which the concentration of quinine in a sample of tonic water was quantified by measuring the fluorescent emission intensity of the substance. Moreover, the study’s additional objective was to try to establish the effect of heavy atoms on fluorescence is commonly understood as the glow of substances not accompanied by heat production but initiated by absorption of photons.
Figure 1. Structure of Quinine.
Experimental
Reagents
Sulfuric acid, H2SO4, high purity
Potassium bromide, KBr, high purity
Potassium iodide, KI, high purity
Quinine, C20H24N2O2, high purity
Solutions
sulfuric acid, 0.050 M. 3.0 mL of concentrated sulfuric acid was quantitatively transferred into a flask and diluted with 500 mL of distilled water. After vigorous stirring, the solution was transferred into a 1 L flask and diluted with distilled water to the mark.
stock quinine,μg/mL. 0.3125 g of quinine were dissolved in 100 mL of 0.050 M sulfuric acid solution. After vigorous stirring, an additional amount of sulfuric acid was added until the mark was reached in 250 mL.
working standard quinine,μg/mL. 2 mL of stock quinine were quantitatively transferred to a 250 mL flask and brought to the mark with a 0.050 M sulfuric acid solution.
potassium bromide,M. 0.2980 g of potassium bromide was placed in a 100 mL flask and diluted with distilled water to the mark.
potassium iodide,M. 0.4500 g of potassium iodide was placed in a 100 mL flask and diluted with distilled water to the mark.
Instrumentation
Cary Eclipse FL1005M010.
Procedure
This laboratory work was performed as described in the Instrumental Methods of Analysis Chem 447 Winter 2020 manual experiment titled Determination of Quinine in Tonic Water with Fluorescence Spectroscopy, and the External Heavy Atom Effect on Fluorescence written by Judith Bazzi. A series of five mixtures with different working solution concentrations was created by adding 0.050 M sulfuric acid to a given amount of the active substance.
Additionally, fivefold series for potassium bromide (0.025 M) and potassium iodide (0.0271 M) were prepared by mixing aliquots of different volumes of salt with 10 mL of working solution of quinine and the required amount of 0.050 M sulfuric acid. A sample of tonic water containing an unknown concentration of quinine was dissolved with 0.050 M sulfuric acid to the 100 mL mark: this procedure was performed three times to achieve more reliable results. The prepared solutions were examined qualitatively using a spectrofluorometer to create a calibration curve and subsequently establish quinine concentration.
An additional procedure preceding the examinations was to determine the necessary and sufficient conditions for recording the fluorescence. For this purpose, a sample of the calibration solution was placed in the cell of the apparatus and measured at a photomultiplier tube voltage range of 400 V to 800 V in increments of 50 V. After selecting the actual empirical parameters, spectroscopic measurements were made for a series of previously prepared solutions.
Results and Discussion
For a series of calibration solutions, the intensity of fluorescence radiation was measured at different photomultiplier tube voltages. The graphical dependence of intensity on voltage is shown in Figure 2, from which it can be noted that the optimum value of PMT voltage was 700 V. The choice of this value was justified by the boundary condition, at which the graph shows a rapid increase after this value. To put it another way, a voltage of 700 V was the maximum sufficient to carry out further investigations.
Figure 2. The dependence of the working solutions’ fluorescence intensity on the photomultiplier tube’s voltage allows identifying the point of optimal voltage: it was 700 V.
The optimal voltage was used to examine the dependence of the emission intensity on the amount (ppb) of quinine in the working standard solutions as shown in Table 1. The linear regression for working standard solutions is shown in Figure 3. This regression automatically projected for this relationship has high reliability, as evidenced by the square of the coefficient of determination. This was well supported by the data from equation 2.
Quinine WS Series
VWS, mL
Vsol’n, mL
ppb of quinine
fluorescence intensity700, a.u.
2.00
25.00
0.8
38.242
5.00
2
169.285
10.00
4
412.862
15.00
6
740.073
20.00
8
969.793
KBr series plus 10 mL WS Quinine
VWS, mL
Vsol’n, mL
VKBr, mL
CKBr, M
fluorescence intensity700, a.u.
10.00
25.00
1.00
1.00×10-3
508.175
2.00
2.00×10-3
430.820
5.00
5.01×10-3
339.111
10.00
1.00×10-2
236.110
KI series plus 10 mL WS Quinine
VWS, mL
Vsol’n, mL
VKBr, mL
CKI, M
fluorescence intensity700, a.u.
10.00
25.00
1.00
1.08×10-3
460.248
2.00
2.17×10-3
293.495
5.00
5.42×10-3
198.002
10.00
1.08×10-2
124.420
Table 1. Concentration for Working Solutions of Quinine, Potassium Bromide, and Potassium Iodide and Measured Fluorescence Values.
Figure 3. Linear Dependence of Fluorescence Emission on the Amount (ppb) of Quinine in a Series of Standard Solutions.
A linear regression equation was used to determine the amount of quinine (ppm) in the two tonic water samples: calculations are presented in equations 3 and 4. The data given are significantly different from the FDA standard, as reflected in equation 5. More specifically, the Agency set the upper limit for quinine in tonic water at 83 ppm1. In addition, the calculated values differ from typical values for tonic water, the quinine content of which varies from 50 to 60 ppm2. Such a marked discrepancy between the results could indicate, for example, a highly diluted quinine tonic solution.
Finally, the last step of the work was to determine the effects of the presence of heavy atoms in the mixture on the fluorescence yield. Samples of potassium bromide and potassium iodide of equal concentrations were used for this purpose. Hence Figure 4 illustrates how the fluorescence intensity of quinine depended on these compounds’ concentration. Most noticeably, the less heavy potassium bromide had less effect on the decrease in intensity, which means that the presence of heavy atoms causes it. In addition, the higher was the concentration of the impurity compound, the lower was the final intensity of emission. These effects can be determined by the phenomenon of fluorescence quenching initiated by particle collisions or the formation of non-luminescent products.
Figure 4. Dependence of Quinine Fluorescence Intensity on the Concentration of Impurity Compounds: Potassium Bromide (Orange) and Potassium Iodide (Yellow).
Summary
In this work, a spectrographic study of the concentration of quinine in tonic water samples was carried out using fluorescence. In particular, the concentration of an organic molecule emitting upon excitation was determined using the calibration method, and it was confirmed that the relationship between the substance concentration and the fluorescence intensity was close to linear. The determined amounts of quinine in the two tonic water samples were 1.47 ppm for 5 mL and 4.18 ppm for 10 mL or 2.825 ppm on average with %RSD = 67.9%.
This value shows an insufficient level of confidence in the data. Such errors could have been caused by an outdated tonic water preparation, measurement errors, or inherently low quinine content in commercially available samples. In addition, it has been shown that the calculated amounts of quinine in tonic water differ greatly from the normal values and the maximum threshold set by the FDA. Furthermore, it was shown empirically that the presence of heavy atoms in the mixture initiates quenching of the fluorescence, resulting in a consistent decrease in emission intensity.
Reference
Izawa, K.; Amino, Y.; Kohmura, M.; Ueda, Y.; Kuroda, M. 4.16 Human Environment Interactions — Taste. Comp. Nat. Prod. 2010, II, 631-671.
In the introduction, it was stated that quinine may be excited with two bands centered at 250 nm and 350 nm. Regardless of which band is used to excite quinine, the λ of maximum emission is at 450 nm. What is the reason for this phenomenon?
In fact, quinine has several peaks responsible for different transitions. At 250 nm, the singlet S0→S2 transition occurs at 350 nm S0→S1; however, the maximum peak is observed only at 450 nm, where the S1→S0 level transition occurs. The reason for this effect lies in the simultaneous phenomena of fluorescence and internal transformations initiated by photon absorption. Fluorescence leads to excitation of the molecule, while the substantial overlap of excited states, on the contrary, leads to energy dissipation. As a result, the maximum peak is noticeable at the longest incident wavelength.
Why is fluorescence more sensitive than absorbance spectrophotometric methods? Are there any disadvantages to the fluorescence technique?
The intensity of fluorescence flux is usually measured directly, whereas other spectrophotometric processes’ absorbance is evaluated through the difference between the reference best and the observed one. Despite its obvious advantage, however, fluorescence has a critical disadvantage: not all molecules are able to fluoresce. In addition, this method is susceptible to interference and also has a relatively short analysis time.
Compare and contrast fluorescence and chemiluminescence with respect to instrumentation requirements and design.
Both luminescence methods use the effects of a molecule’s radiation upon excitation, but the design and principle of the equipment used are different. In particular, fluorometers require an external EMR source, whereas a chemical reaction initiates chemiluminescence. In addition, a chemiluminescence spectrometer does not require a set wavelength setting, and since this type, unlike fluorescence, is not multi-wavelength selective, an output wavelength recorder is not required.
What is the difference between excitation and emission spectra? Be sure to point out what is held constant and what is plotted for each?
An excitation spectrum occurs when electromagnetic radiation passes through an absorbing medium that absorbs a certain wavelength’s radiation. Graphically it is a continuous spectrum with dark lines. In other words, it is a picture of light rays after passing through a given substance. On the other hand, emission spectra (constant wavelength) arise when electrons, atoms, particles, or fragments of molecules being excited, go from a higher energy state to a lower energy state. Graphically, this looks like a series of well-separated frequencies, which spectrometers record as bands: the arrangement of these bands indicates a particular element in the gas and is called the atomic spectrum.
Why does fluorescence not take place from the highest vibrational level of the excited state?
Since fluorescence is a slow process, it is a highly undesirable way for a particle to dissipate excess energy, especially in energy states above the first level. Moreover, assuming that higher states initiate fluorescence, it should be noted that energy will be dissipated by vibrational relaxation and internal conversion.
What is the difference between internal and external heavy atom effect?
The external heavy atom effect appears in the case of heavy atoms (halogens) in the medium, which leads to the formation of a system of charge-transfer complexes and, consequently, to quenching of fluorescence. In the case of the internal effect, the heavy atom is chemically incorporated into the molecule under study and covalently bound to it.
Would the fluorescence measurements be affected if the source of quinine used to prepare the solutions were quinine hydrobromide?
Definitely yes, because the structure of quinine hydrobromide contains a bromine atom, which is a heavy particle. Thus, if this compound were used as the quinine source, it would be reasonable to expect lower intensity values.
Water is not stagnant on the earth surface. It evaporates and precipitates back. This process involves absorption of heat by water molecules which leads to breakage of molecular bonds. As a result, water molecules are able to move from the earth surface to the atmosphere through a process known as evaporation.
On the reaching the atmosphere water molecules bond together again and come back to the earth surface through the process of precipitation. It should, however, be noted that the amount of water that leaves the earth surface and the amount that comes back is more or less equal.
How the Process Occurs
When water molecules gain energy from the surrounding, their latent heat increases. Latent heat is gained up to the point where it is able to break the molecular bond that holds water molecules together. Water then changes into a gaseous state known as water vapor. The water vapor is moved from the earth surface to the atmosphere by moving air currents as well as due to increased internal pressure. It is important to note that water vapor can only be absorbed into the atmosphere if humidity is low enough to allow evaporation.
As water vaporizes, its molecules come into contact with molecules of other substances which are relatively cooler than the water molecules. Consequently, water molecules start losing their latent heat through a process known as adiabatic cooling. This process continues until water molecules loose enough energy to allow the molecules to bond together again.
As the temperatures become lower, the molecules come together to form clouds in the atmosphere. With continued evaporation, the specific humidity of the atmosphere increases. Nonetheless, additional water vapor can be absorbed until dew point is reached. Dew point is reached when air is fully saturated and can no longer hold any more water vapor. As a result, water vapor condenses and falls back to the earth surface. This process is known as precipitation.
It should, however, be noted that it is not always that the process of condensation takes place completely. If condensation takes place completely, precipitation will occur in form of rain. Nevertheless, when water molecules are not fully condensed, they remain suspended in the air resulting to fog or mist. There are other forms of precipitation which include hail, snow and sleet. Notably, evaporation and precipitation take place at different rates in various regions.
This is due to the difference in pressure and temperature which influences saturated specific humidity hence the amount of water vapor that can be held. Arguably, evaporation and precipitation help in maintaining a constant cycle of water in the world. It is not definite that evaporation and precipitation will occur at the same place. Water vapor is sometimes pushed to a different place where precipitation takes place.
Factors affecting the process
The whole process of evaporation and precipitation is affected by various factors. Firstly, the speed of wind is highly influential. Increased speed of wind enhances the rate of transportation of water vapor and hence the rate of evaporation. In addition, humidity is very crucial. When humidity is high the rate of evaporation decreases because the rate of absorption of water vapor is low. On the same note, high temperatures increase the latent heat absorbed by water molecules hence increasing evaporation rate.
Water Holding Capacity (WHC) is an essential technological production parameter that determines the ability of chicken to absorb and contain moisture. In terms of consumer appeal, low WHC values give the chicken a visually deficient appearance, expressed as excessive pallor, inappropriate texture, and dry meat. For this reason, the study of patterns related to the moisture content in chicken is one of the critical objectives of production technology; one such predictor is the medium acidity index. In the present laboratory work, the main issue is to investigate the potential relationship between WHC as a measure of moisture content and chicken pH; specifically, the question is to identify the effect of meat pH on WHC. Determining the relationship between these two variables allows for a deeper understanding of processes to optimize production steps.
Results
Direct measurements for fifteen chicken meat samples yielded mass values (in grams) for both raw but acid-treated and cooked meat. Table 1 below shows the results of the direct measurements. For each sample (3 cm thickness), the weight is given both after treatment with acetic acid (column 4) and after cooking (column 5), as well as the original weight corresponding to the raw chicken disc before any interventions (column 3). In addition, the table contains information on the pH measurement for each of the chicken meat treatments, whether acidification or cooking in a water bath at 80°C. Notably, after treatment of the chicken meat samples with acetic acid, the mass of each disk increased by an average of 3.026 g, which may indicate that the samples absorbed liquid over time, with the maximum increase in mass being true for the maximum acid concentration.
Table 1. Results of direct measurements for each chicken sample.
Based on the weights of the chicken samples after and before the return, it was possible to set the water holding capacity factor by dividing the first by the second. For example, for the first sample, WHC was calculated by dividing 7.080 g by 6.715 g for the acid-treated disc and 3.645 g by 6.715 g for the water-cooked disc. Table 2 shows the calculated values for each of the fifteen meat discs.
Table 2. Calculated WHC coefficients for acetic acid treated and cooked meat.
The graph of the pH dependence of WHC for raw and cooked meat was plotted based on the available data. Figure 1 shows a graph of these relationships. At first glance, it appears that an increase in pH is inversely related to WHC since the coefficient values decrease as the acidity of the medium increases. On the other hand, the relationship is indeed not linear because it is seen that the decrease in WHC does not occur uniformly as the pH decreases.
Figure 1. Dependencies of WHC on pH value for the two types of treatment.
Discussion
This laboratory work aimed to identify the pH dependencies on WHC. The pH was measured once for each sample, in the intermediate period between the acid treatment and the water bath cooking, using a pH meter whose probe tip was placed in the center of the disk. The values obtained determined that the relationship between WHC and pH was not linear and showed a downward trend. This meant that as the acidic environment increased, the WHC decreased.
At first glance, the results seem to contradict theoretical expectations. Academic discourse reports that as pH increases, WHC values should also increase (Khidhir, 2019). However, this is true for high pH values, whereas for low values, the WHC does fall as the acidity of the medium increases (Jankowiak, Cebulska, and Bocian, 2021). Thus, the overall dependence of WHC on pH is inverted bell-shaped. The main reason for this pattern is the isoelectric point, a certain physical and chemical state of the system in which the number of positive and negative charged particles is identical; in this case, a minimum WHC is observed for meat (QPC, 2020). In the case of low pH values, however, there are more positive particles (protons from the acid) in the medium, resulting in bipolar proteins turning into positively charged protein particles with NH3+ ends. The surplus content of positively charged proteins binds water molecules through the negatively charged O-end of the molecule, which contributes to removing water from the meat composition. In other words, the liquid medium absorbs excess water, causing the WHC to drop. WHC values for raw meat were higher on average than for cooked meat, as follows from Figure 1. A likely reason for this could be the cooking process, which causes the chicken proteins to denature and are no longer able to retain moisture in the same way that the non-denatured molecules did.
WHC significantly affects meat because it determines the consumer properties of the product. Maximizing moisture retention in the meat structure allows for the product’s attractive traits, including texture and appearance. At the isoelectric point, the WHC value turns out to be minimal. In this case, the proteins are bipolar, which eliminates excessive water retention or expulsion, as observed at higher or lower pH values. To improve the work, it is possible to investigate the effect of acid concentrations and the nature of these acids on the WHC, which will deepen the knowledge of the topic.
Conclusion
To summarize the present laboratory work, the effect of pH on WHC for raw and cooked meat was evaluated. It was determined that the WHC decreases with increasing pH values, which is true for low acidity levels (3.57 to 6.37 in this work). This meant that in areas of low acidity, excessive amounts of positively charged protein particles caused water to be pushed out of the meat structure, negatively affecting consumer appeal parameters. In this context, it is evident that increasing pH (in the region up to the isoelectric point) negatively affects product quality and is not a desirable measure.
Reference List
Jankowiak, H., Cebulska, A. and Bocian, M. (2021) ‘The relationship between acidification (pH) and meat quality traits of polish white breed pigs’, European Food Research and Technology, 247(11), pp. 2813-2820.
California is the third-largest state in United States situated in the western coastal region. It is a well-developed state with various activities as well as having high population of around 37 million people. In this state, there is a well and organized water distribution system for water utilization as compared to the other states of the United States. Nowadays, California has various water reservoirs- one of the advantages the state has, becoming the leading agricultural state in United States as well as worldwide. With well-developed water reservoirs, storage and formation of many projects, California transformed its natural resources as well as desertification environment into a productive farmland (Carle, 33-46).
Main Body
There is less rainfall in California and most cities in this state receive less than 20 inches of rainfall yearly. The economy of California State has grown rapidly due to the presence of well-distributed water systems in most cities within the state. The distributed water comes from industries, developers and manufacturers within the state. Well-organized water distribution plants from different cities have distributed quality water to their customers, giving a reputation to the distribution system body in California States. The harnessing and capturing of water in dams, reservoirs and rerouting it in concrete rivers within the cities of California has made the distribution bodies feel proud (Outwater, 5-16).
It is useful to take and use treated water every time as directed by health bodies in the medical department in our homes. This helps to control water-borne diseases like cholera and typhoid that affect a number of people within a given area. Water in California State sometimes exposes to chemicals from industries as well as sewages that carry harmful microorganisms, which are vulnerable to an outbreak of diseases. However, many plants in California State use high technology to ensure that water distributed is of higher quality before it reaches the consumers’ tap. Microbial found deep in water supply distribution systems are threats to water channels hence, the results in water quality degradation (Geldreich, 45-62).
Larger plants have abilities to treat water acidity, alkalinity, color, hardness, taste and odor through their own laboratories, before supplying their products to customers. Meanwhile, most plants use basic techniques when treating water by applying fluoride to regulate tooth decay in water drainage. All these methods of water treatment vary from one community to the other due to the contamination of the different systems realized within different cities in California State.
Most piping systems installed in California State use polybutylene, galvanized, copper and kites pipes. Meanwhile, copper is widely used in piping systems. It is strong and lasts for a longer period of around 25 to 50 years. The level of acidity in water affects copper piping systems by creating leakages; hence, the distributors through water treatment programs control this problem. In 2005, California water distribution systems enacted an amendment code by setting copper PVC as the standard plumbing material to use when doing piping installation. The results of the research made showed that copper was portable to hot and cold water (Frankel, 66-87).
Many plants associated with water distribution uses natural gases to provide pressure in the piping systems. Many plants use complex standard delivery pressure systems to control the cost of piping within the state. Meanwhile, the engagement of water distribution Companies into the provision of high-pressurized water to their clients has regulated the size and the cost of gas piping, leading to the growth of economy in the California state. The use of pressurized systems in water distribution is less costly as compared to electricity.
California State uses air tankers when fighting against fire. The S2 tankers drop retardant foam: hence, water does not mix with retardant foam. This is the most efficient system since it consumes less time when fighting fire in most cities in California State. However, hydrants water may be applicable in those areas far from offshore and lakes. The hydrant affects water piping systems as well as reservoirs by contaminating water- a threat that results in the outbreak of water-borne diseases (Heyden, 72-93).
Conclusion
Overall, being a desert state in United States, California has emerged as one of the leading agricultural states in the world. The cities of California have developed well-organized water distribution systems that serve their communities. The economy of California State has grown rapidly due to the presence of well-distributed water systems in most cities within the state. However, many plants in California State use high technology to ensure that water distributed is of higher quality before it reaches the consumer’s tap. Copper PVC is a standard plumbing material used when doing the piping installation
The level of acidity in water affects copper piping systems by creating leakages; hence, the distributors through water treatment programs control this problem. Many plants use basic techniques when treating water by applying fluoride to regulate tooth decay in water drainage. The hydrants water system is applicable in those areas far from offshore and lakes; since most parts of the state uses S2 tankers to fight against fire outbreaks.
Works cited
Carle, D. Introduction to Water in California (California Natural History Guides). United States: University of California Press. 2009.
Frankel, M. Facility Piping Systems Handbook: For Industrial, Commercial, and Healthcare Facilities. United Kingdom: McGraw-Hill Professional. 2009.
Geldreich, E. Microbial quality of water supply in distribution systems. United Kingdom: 1996.
Heyden, V. Description of Fire Engines with Water Hoses and the Method of Fighting Fires Now Used in Amsterdam. New York: Science History Publisher. 1996. Outwater, A. Water: A Natural History. California: Basic Books. 1996.
Adham, S., Hussain, A., Minier-Matar, J., Janson, A., & Sharma, R. (2018). Membrane applications and opportunities for water management in the oil & gas industry. Desalination, 440, 2-17. Web.
The importance of water management and its application in the oil industry is the primary focus of Adham et al. (2018) in this article. The oil and gas industry depends much on water management. According to Adham et al. (2018), advanced methods are needed for water treatment to eliminate the present challenges. Membrane bioreactor processes are examined as a viable technological tool that can potentially impact water treatment. This article is crucial in understanding water management principles and their implications on the oil and gas industry.
Azhoni, A., Jude, S., & Holman, I. (2018). Adapting to climate change by water management organizations: Enablers and barriers. Journal of Hydrology, 559, 736-748. Web.
In this article, Azhoni et al. (2018) address climate change in line with water shortage. Water resource management has been affected by various enablers and barriers. The article analyses literature in line with water management programs. This research facilitates a deeper understanding of past and current management issues. The importance of this article is promoting the development of future multi-scale management programs spanning across many organizations.
Datta, A., Ullah, H., & Ferdous, Z. (2017). Water management in rice. In Chauhan, B., Jabran, K., & Mahajan, G. (eds) Rice Production Worldwide. Springer, Cham. Web.
The article by Datta et al. (2017) discusses the challenges of rice production brought about by water shortage. According to the authors, rice production requires plenty of water ( Datta et al., 2017). Due to water shortages in many countries, there is a need for improved rice production methods. The methods highlighted facilitate water conservation, thus alleviating the water challenges. This article is essential in developing viable solutions for agricultural production and water resource management.
Eggimann, S., Mutzner, L., Wani, O., Schneider, M., Spuhler, D., Moy de Vitry, M., Beutler, P., & Maurer, M. (2017). The potential of knowing more: a review of data-driven urban water management. Environmental Science & Technology, 51(5), 2538-2553. Web.
Eggimann et al. (2017) show the impacts of utilizing large volumes of data in urban water management (UWM). The role of data-driven UWM in facilitating sea change is addressed in the article. According to Eggimann et al. (2017), the future of UWM lies in the collection, analysis, and utilization of data. This article is relevant in the current efforts for water management in many urban applications. This information is crucial for integrating network-based and novel technological solutions in water management.
Kamienski, C., Soininen, J., Taumberger, M., Dantas, R., Toscano, A., Salmon Cinotti, T., Maia, R.F., & Neto, A.T. (2019). Smart water management platform: IoT-based precision irrigation for agriculture. Sensors, 19(2), 276. Web.
Agriculture is one of the sectors that should be considered about water resources management, according to Kamienski et al. (2019). This article addresses the need for precision irrigation through smart water management. The development of intelligent water management techniques depends highly on IoT applications. The authors discuss a SWAMP technique that presents a practical solution to water management issues related to agriculture. This article is essential because the techniques and processes highlighted here provide a solution for water management globally with a particular focus on the agricultural sectors.
Nazari, B., Liaghat, A., Akbari, M., & Keshavarz, M. (2018). Irrigation water management in Iran: Implications for water use efficiency improvement. Agricultural Water Management, 208, 7-18. Web.
Water management depends on its utilization in the various sectors of the economy, as highlighted by Nazari et al. (2018). In this article, the issue of irrigation and its impact on water management are discussed. The authors show that Iran’s water shortage can be attributed to inefficiency in irrigation systems. The role of political, legal, social, and technological changes in water use have been elaborated. This article is crucial in understanding the root causes of water problems and how to mitigate them.
Neupane, J., & Guo, W. (2019). Agronomic basis and strategies for precision water management: A review. Agronomy, 9(2), 87. Web.
Jasmine and Guo (2019) argue that agriculture faces an enormous challenge of feeding many people with limited resources available for production. The article illustrates that site-specific solutions of irrigation present the solution to food production challenges. The primary focus is placed on variable-rate irrigation (VRI) techniques and their implications on agriculture. This article is crucial in understanding the current technological solution for resource management and sustainable production. This information can be applied in many countries to increase food production while utilizing scarce water resources.
Novoa, V., Ahumada-Rudolph, R., Rojas, O., Sáez, K., de la Barrera, F., & Arumí, J. (2019). Understanding agricultural water footprint variability to improve water management in Chile. Science of The Total Environment, 670, 188-199. Web.
The article by Novoa et al. (2019) establishes a connection between agriculture, climate variability, and water management. The authors assess the water footprint of the Cachapoal River agricultural basin (34°S 71°W). In their analysis, Novoa et al. (2019) show that regions with high variability of water availability require formulating and enforcing policies on water management. Sustainable water management begins by understanding the water consumption and variability data. This article is relevant because it addresses the root causes of water management challenges and the viable solutions.
Sun, A., & Scanlon, B. (2019). How can Big Data and machine learning benefit environment and water management: a survey of methods, applications, and future directions. Environmental Research Letters, 14(7), 073001. Web.
Sun and Scanlon (2019) discuss how machine learning and Big Data could impact environmental and water management practices. Machine learning has become increasingly important in the deployment of SMART solutions in many sectors. Environmental and water management can benefit from Big Data and machine learning by applying remote sensing and information systems. Increased data availability is crucial in the development of practical solutions to present and future water utilization. This article is relevant to water management because it incorporates technology in finding long-lasting solutions to resource management challenges
Zhupankhan, A., Tussupova, K., & Berndtsson, R. (2018). Water in Kazakhstan, a key in Central Asian water management. Hydrological Sciences Journal, 63(5), 752-762. Web.
Zhupankhan et al. (2018) have addressed the issues pertaining to water management. Their article discusses water management policies in central Asia with a particular focus on Kazakhstan. The article discusses how establishing legal frameworks for water management, and inter-boundary cooperation can alleviate the water deficiency in Central Asia. This article is important because it highlights some viable solutions to water management problems around the globe. The concepts addressed in this article apply to any other country or region.
Datta, A., Ullah, H., & Ferdous, Z. (2017). Water management in rice. In Chauhan, B., Jabran, K., & Mahajan, G. (eds) Rice Production Worldwide. Springer, Cham. Web.
Nazari, B., Liaghat, A., Akbari, M., & Keshavarz, M. (2018). Irrigation water management in Iran: Implications for water use efficiency improvement. Agricultural Water Management, 208, 7-18. Web.
Sun, A., & Scanlon, B. (2019). How can Big Data and machine learning benefit environment and water management: a survey of methods, applications, and future directions. Environmental Research Letters, 14(7), 073001. Web.
Everyone should have access to safe drinking water. It is possible to address the issues that prevent certain people from accessing safe drinking water. The people face challenges as they live in overcrowded slums in urban areas and in refugee camps. There are others who live in the rural areas of the developing countries which are greatly poverty-stricken. Unfortunately, they have no political power to ensure that their right to safe drinking water is enforced.
The leaders have neglected to provide resources for them to access safe drinking water. These people are estimated to be about one billion in the world (Global Water, 2010). International organizations are penetrating these countries and with the financial assistance of donors, they are providing resources for these people in order for them to live a healthy life. There is underground water in even the most arid areas and the government and the international community can assist by digging wells for these communities.
Water shortage and Food Supply
Food supply and water shortage are inter-related. The population has been rapidly increasing causing the demand for food to also increase. In those areas where there is water scarcity, they are not able to participate in agricultural activities. The crop life withers and dies. The livestock also die due to hunger.
There is also the adverse effect on the population. The people become weak and are not even able to participate in farming. Others get water-borne diseases such as cholera and typhoid from utilizing water that is dirty. The limited crop produce that the community could have harvested is not even harvested well due to decreased labour. It is estimated that over three million people suffer and die from water-borne diseases annually (Water.org, 2012). As the water shortage increases, there will be growing food insecurity in the world.
Addressing the global water shortage
It is possible to ease the global water shortage especially in the developing countries. There are cost-effective ways to do it. It is not enough for the governments to provide food for the poor people but it is important to equip them with the resources to access clean water and participate in farming. This will cause them to stop utilizing dirty water for their activities. There are two main ways to address the problems.
The first is to dig wells in the rural and arid areas to aid the people to have access to water. The other alternative is to treat water and use it in the home. The increasing population in the world requires water saving measures to be applied. There are technologies available to ensure high water quality. The harmful micro-organisms and chemical contaminants are removed. The people can also be educated on efficient and safe distribution techniques to ensure the water does not become dirty.
Environmental challenges and water shortage
In periods of water shortages the environment is adversely affected. When it comes to the ecosystem, there will be animal and plant life unable to survive in certain areas. The drought makes it hard to grow certain crops. Animals will travel long distances to look for areas where they can find water.
The change in the ecosystem affects the other animals which rely on the animals and crops as food creating imbalance (World Water Council, 2012). It is therefore important for governments and other international organizations to address the water shortage problems.