PH

You learned in general chemistry that pH is the negative log of the molar hydrogen ion concentration Ions in water are always surrounded by water molecules that partially cancel out the charge of the ion. The hydrogen ion, like all ions in solution, is surrounded by waters of hydration. For ease of writing, we normally represent the hydrogen ion as H3O+, suggesting one water of hydration, although in reality it can have 5 to 9. In fact, it is a cluster of water molecules with one extra proton....

Basic Input Sources Wastewater Flow Rates And Bod Levels

The Streeter-Phelps equation is designed to model the oxidation of any constant (step) input of oxidizable waste flowing to streams. Thus, the input source can be a variety of point and non-point sources, including the waste from domestic sewage plants, food-processing facilities, and inputs from livestock feedlots and agricultural settings. The only wastewater parameters that must be known are the flow rate of wastewater, the temperature of the wastewater, the DO of the wastewater (usually...

The Concept Of Risk

What is an acceptable risk This is a major, and largely unanswerable, question. In order to attempt to answer this question, we will first look at commonly accepted risks that each of us exposes ourselves to every day. Table 10.1 shows the annual risk associated with a variety of actions. These are listed in decreasing degree of risk and show that smokers routinely accept an increased mortality risk of 3600 per million that is, for every one million smokers, 3600 or 0.36 of them will die each...

List Of Contaminants And Their Mcls Epa 816F02013 July 2002

List of Contaninants and Their MCLS (EPA 816-F-02-013, July 2002) (mg L)2 (mg L)2 Potential Health Effects from Ingestion of Water Sources of Contaminant in Drinking Water Heterotrophic plate n a TT3 (including fecal coliform and E. coli) Gastrointestinal illness (e.g diarrhea, vomiting, cramps) Gastrointestinal illness (e.g diarrhea, vomiting, cramps) HPC has no health effects it is an analytic method used to measure the variety of bacteria that are common in water. The lower the concentration...

[H2 pT

Then the previous equations for the diprotic system can be simplified to By taking the log transform of each equation, we now have equations describing every line in the pC-pH diagram. The utility of a pC-pH diagram is that all of the ion concentrations can be estimated at the same time for any given pH value. The computer program (the pC-pH Simulator) used to create this diagram, included with your textbook, allows the user to select an acid system, enter the pK values, and draw the pC-pH...

And Amendments

The Clean Air Act is probably the most amended environmental act in U.S. history. While we would like to think an act is amended because of increased knowledge or tightening of pollutant emissions, this has not necessarily been the case with the Clean Air Act. Although, in general, air quality has improved since the introduction of clean air legislation in 1955, some critics of the process feel we have regressed in our efforts by deregulating what we are having trouble controlling or what we...

Ingestion of Water While Swimming

Exposure from ingestion of water during swimming can be calculated by Intake of water (mg kg day) - (10.2) where CW is the pollutant concentration in the water (mg L), CR is the contact rate (0.050L hr EPA, 1989b), ET is the exposure time (hours swimming event), EF is the exposure frequency (swimming events year, national average is 7 days year), ED is the exposure duration 70 years (lifetime), 30 years (national upper-bound time (90th percentile) at one residence), 9 years (national median...

Safety and Hazards

As in all laboratory exercises, safety glasses must be worn at all times. All of the chemicals used in this laboratory are relatively safe, but standard laboratory cautions and safety should be practiced. You will spill and spread dilute flourescein solution everywhere in this lab. Dilute concentrations are safe when spilled on your skin, but may turn your skin yellow for a brief time. We recommend wearing latex gloves during this laboratory exercise. Student Procedures. Your laboratory...

Important Factors In The Modeling Of Streams Conceptualization Of Terms

In order to describe a stream mathematically, we must first make a list of variables (mathematical symbols) for the important terms SA is the cross-sectional area of the stream (width, w, multiplied by average depth, d) (m2). Qi is the flow rate at the beginning of the section of the stream to be modeled (m3 yr). Qe is the flow rate at the end of the section of the stream to be modeled (m3 yr) (we usually assume that Qt is equal to Qe and we represent both by simply C(x) is the pollutant...

Bioconcentration Calculations

In Chapter 2 and 3, we discussed bioconcentration and looked at DDT data from a food chain on Long Island, NY (Table 2.3). The data from Table 2.3 are reproduced in Table 10.10, where we used it to calculate bioconcentration factors (BCFs) for each animal species. Each BCF is calculated by dividing the DDT concentration in each animal by the water concentration. As you can clearly see, DDT is increasingly bioconcentrated as we move up the food chain, from 800 in the first tropic level to...

Kinetics Of Transformation Reactions

In Chapters 2 and 3, we have looked at various chemical processes that are important in understanding how chemistry affects fate and transport. These have included acid-base, precipitation, and oxidation-reduction processes and sorption equilibrium. These processes affect the transport but do not necessarily account for any removal of pollutants from the system under study. As noted earlier, most sorption equilibrium reactions are reversible if they were not, we would not be concerned with...

The National Environmental Policy

The National Environmental Policy Act (NEPA) is the Magna Carta of environmental law. Yet there are few today, even among environmentalists, who know what the law contains or understand the potential it once had, and may still have, to shape the U.S. federal policy toward the environment. The statute has been misunderstood ever since it was signed into law by President Nixon on January 1, 1970. There are four main purposes to the Act (NEPA, 1969) (1) to declare a national policy which will...

Remediation

No text on pollutant fate and transport would be complete without considering remediation of the contaminated system. Thus, each fate and transport chapter in this book (Chapters 5-9) will close with a section on remediation. Each environmental system discussed in this book presents a unique set of conditions, and thus problems, with respect to remediation. Issues specific to lakes include the hydraulic retention time, t0, introduced in Section 5.5.2, which is determined by the total volume of...

Physical Parameters Important In Pollutant Fate And Transport

In Section 8.4, we mentioned the importance of bulk density and porosity in relating Kd and Kp to retention (R) in a aquifer or column. These physical measurements are also important in estimating water velocity. In rivers and lakes, logically, the water flows downhill, and it is also generally easy to tell how fast the water is flowing with a tool as simple as a tennis ball. But in aquifers, where we cannot see the slope of the water table, it is difficult and in many cases impossible to...

Putting It All Together Where Chemistry Enters Into The Modeling Effort

We have covered many important and complicated chemical concepts in Chapters 2 and 3. But where do they all fit into the pollutant fate and transport modeling approach, and when is each important It depends on the pollutant and the environmental system under study, but we will attempt to summarize the role of chemistry in the modeling effort. We will divide our discussions into a metal pollutant and a hydrophobic (organic) pollutant, and important chemical processes are summarized in Table 3.3....

Student Procedures

To 250-mL or 300-mL sample bottle full of sample, add 1mL MnSO4 solution, followed by 1 mL alkali-iodide-azide reagent. If your pipets are dipped into the sample (as they should be), rinse them before returning them to the reagent bottles. If the solution turns white, no dissolved oxygen is present. 2. Place stoppers on the sample bottles in a manner to exclude air bubbles and mix by rapidly inverting the bottle a few times. When the precipitate has settled to half the bottle volume, repeat the...

Info

A linear calibration model. Figure 4.1. A linear calibration model. the response over to the calibration line and then down to the concentration line and determine the concentration of pollutant in the sample (6.49mg L in this example). This is typically how instrumental measurements are made. This concept can be extended to environmental systems, where we look at flow rate and travel time in a system. If the water or wind flow rate is 2.00 m sec, then we can calculate that it will...

Stratification Of Lake Systems

Most lakes undergo some form of thermal stratification during the year. Stratification is a process in which differential heating or cooling occurs and two climates are set up in the lake. If a lake undergoes only one stratification event during the yearly cycle, it is referred to as a monomictic lake. The most common stratification scenario is illustrated in Figure 5.3b. Figure 5.3a shows the unstratified lake during Figure 5.3. Stratification of lakes during annual cycles. Figure 5.3....

Suggested Papers For Class Discussion

Looney, and J. D. Thornton. Airborne organic contaminants in the Great Lakes ecosystem. Environ. Sci. Technol. 15(1), 30-38 (1981). Holloway, T., A. Feore, and M. G. Hastings. Intercontinental transport of air pollution Will emerging science lead to a new hemispheric treaty Environ. Sci. Technol. 37(20), 4535-4542 (2003). Engstrom, D. R., E. B. Swain, T. A. Henning, M. E. Brigham, and P. L. Brezonik. Atmospheric mercury deposition to lakes and watersheds A quantitative...

Total Suspended Solids TSS and Total Dissolved Solids TDS Measurements

In this procedure, you will first use 100mL of your sample to perform the most commonly used solids measurement, the total suspended solids (TSS). This requires you to filter a known volume of sample through a pre-heated and pre-tared glass-fiber filter, to remove the suspended solids. The difference between the initial (just filter) and final (filter with solids) weights, divided by the volume of sample, will yield the TSS. The TSS measurement accounts for all solids that do not pass...

Determination Of A Claywater Distribution Coefficient For Copper

To determine the distribution coefficient of a metal on a characterized soil. Background. Perhaps the most important fate and transport parameter is the distribution coefficient, Kd. The distribution coefficient is a measure of adsorption phenomena between the aqueous and solid phases and is fundamental to understanding processes responsible for the distribution of pollutants in aquatic systems. For applications of the distribution coefficient to fate and transport modeling of...

Mathematical Development Of Model

As discussed in Chapter 4, the derivation of the fate and transport equations used in this textbook requires that the student has taken linear algebra or differential equations. Since this textbook is designed for students who have only taken college chemistry and algebra, we will skip the derivation and simply state the governing fate and transport equation. A more mathematical derivation is given in the background section of Fate for the Streeter-Phelps module. The Streeter-Phelps equation...

The Determination Of The Biochemical Oxygen Demand Bod Of Sewage Influent Bod5 Andor Bod20

To determine the biochemical oxygen demand (BOD) in a domestic wastewater sample. Background. The focus of this laboratory exercise will be to determine the amount of oxidizable organic matter (sewage) in a wastewater sample. As we discussed in the dissolved oxygen chapter, the term DO refers to the chemical measurement of how much dissolved oxygen is present in a water sample, expressed in mg L. The biochemical oxygen demand (BOD) is an estimate of how much total DO is required to...

Health Risk Calculations For Carcinogens

Perhaps the most disputed, but very important, aspect of determining the effects of a pollutant on human health is our attempt to estimate the increase in cancer risk in a population exposed to the pollutant at a specific concentration. We start with the standard approach of developing a dose-response curve, such as the one shown in Figure 10.1, by exposing an animal to increasing concentrations of pollutant. After a given time period days, months, or even a lifetime the animal is sacrificed...

Calculation Of The Free Metal Ion Concentration In Natural Waters

3.2.1 Calculating Chemical Equilibria Students begin their study of chemical equilibrium in general chemistry with basic equilibrium expressions and Le Chatelier's principle. However, these courses rely on many simplifications regarding equilibria. These simplifications were fine when you were working in simple solutions solutions containing only one or two salts at low concentration but are rarely acceptable in environmental chemistry (as in groundwater, estuary, and ocean water). Courses in...

Historic Examples Of Where Fate And Transport Modeling Are Useful

There is no lack of unfortunate and disastrous pollution events that fate and transport models have been applied to in an effort to better understand and be able to predict pollutant movement in the environment. These are divided into surface water, groundwater, and atmospheric events. You may recall many of the events, discussed below, from news reports or case studies that you have covered in other classes. The Release of Biochemical Oxygen Demand (BOD) Waste to Streams. One of society's...

Mathematical Development Of Simple Transport Models

As discussed in Chapter 4, the derivation of the fate and transport equations used in this textbook requires that the student has taken linear algebra or differential equations. Since this textbook is designed for students who have only taken college chemistry and algebra, we will skip the derivation and simply state the governing fate and transport equation. A more mathematical derivation is given in the background section of Fate for the river and stream module. As we also discussed in...

Methods For Determining Kd AND Kp

As discussed in Chapter 2, distribution coefficients are central to our modeling of equilibrium sorption processes in environmental media. First, we will mathematically define several terms (refer to Table 2.6 for a description of their use) For partitioning between the aqueous phase and dissolved organic matter K _ Conc. of pollutant in DOM (mg kg) DOM Conc. of pollutant in water (mg L) For distribution between the aqueous phase and particles in solution K _ Conc. of pollutant on particle (mg...

Mathematical Models

Instantaneous (Pulse) Pollutant Input. If we assume the spill contaminates the entire thickness of the aquifer, as shown in Figure 8.22, an equation can be obtained using Laplace transformation to predict the pollutant concentration as a function of time or distance from the point source Figure 8.22. An illustration of an instantaneous (pulse) input of pollution to an aquifer. Figure 8.22. An illustration of an instantaneous (pulse) input of pollution to an aquifer. where x is distance from the...

The Determination Of Hardness In A Water Sample

In the past, water hardness was defined as a measure of the capacity of water to precipitate soap. However, current laboratory practices define total hardness as the sum of divalent ion concentrations, especially those of calcium and magnesium, expressed in terms of mg CaCO3 L. There are no known adverse health effects of hard or soft water, but the presence of hard waters results in two economic considerations (1) Hard waters require considerably larger amounts of soap to foam and clean...

Reactions And Equilibrium

The three basic types of chemical reactions are precipitation, acid-base, and oxidation-reduction. We covered precipitation to the extent necessary in Section 2.4.2 (and we will cover it again in Section 3.2.2). We will spend a little more time covering acid-base and oxidation-reduction reactions in this section. First, we will extend your knowledge of acid-base chemistry through the concept of buffers and pC-pH diagrams. By far the most important buffer system in nature is the carbonate...

The Federal Insecticide Fungicide and Rodenticide Act FIFRA

The passing of the FIFRA in 1947 was the first attempt to regulate the manufacture and use of pesticides across the nation. Although the enforcement efforts, and thus the act itself, were weak, the act was a starting point for a major movement. The act was amended in 1972 in 1988, to regulate all phases of pesticide sale, use, handling, and disposal and in 1996, under the Food Quality Protection Act FQPA , to establish tolerances for pesticide residues in food. The heart of FIFRA is the...

Two Basic Mathematical Models For Lakes

As discussed in Chapter 3, the derivation of the fate and transport equations used in this textbook requires knowledge of linear algebra or differential equations. Since this textbook is designed for students who have only taken college chemistry and algebra, we will skip the derivation and simply state the governing fate and transport equation. A more mathematical derivation is given in the background section of Fate for the lake module. By substituting the mathematical terms for mass input,...

Putting It All Together Margin Of Error Uncertainty Of The Entire Estimation Process

We are finally at the culmination of a long and complicated discussion of source characterization, chemistry, fate and transport modeling, and now risk assessment. But how good are our risk assessment values We have discussed a number of precautions in every chapter. The major ones include the following 1. Every number we generate in our modeling efforts depends on an accurate characterization of the waste site or polluted system with respect to pollutant mass dumped or contained in the system....

Sources Of Pollution

As with types of waste, there are many ways of categorizing sources of waste or potential pollutants . We will only mention a few of the more useful approaches and give examples of generated volumes from major industrialized countries. First, we will discuss point and nonpoint sources. Sources of pollutants are commonly divided into one of two types, point or nonpoint sources. Point sources are well-defined sources such as the end of a pipe, smoke stack, or drain. Nonpoint sources are less well...

The Determination Of Dissolved Oxygen In Water Using The Winkler Method Iodiometric Titration Method

To determine the dissolved oxygen DO concentration in a water sample. To learn the chemical reactions involved in the Winkler DO method. Background. It is a common perception that all life is dependent upon the presence of oxygen, either in the atmosphere or in the water. However, this is anything but true. The first lifeforms to evolve on Earth are thought to have been anaerobic, requiring an oxygen-free environment to grow. In fact, free oxygen is toxic to anaerobic organisms'...