New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here

Geography of Environmental Systems

by: Ferne Wiza

Geography of Environmental Systems GEOG 110

Marketplace > University of North Carolina - Chapel Hill > Geography > GEOG 110 > Geography of Environmental Systems
Ferne Wiza
GPA 3.64


Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Class Notes
25 ?




Popular in Course

Popular in Geography

This 20 page Class Notes was uploaded by Ferne Wiza on Sunday October 25, 2015. The Class Notes belongs to GEOG 110 at University of North Carolina - Chapel Hill taught by Staff in Fall. Since its upload, it has received 33 views. For similar materials see /class/228662/geog-110-university-of-north-carolina-chapel-hill in Geography at University of North Carolina - Chapel Hill.


Reviews for Geography of Environmental Systems


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 10/25/15
Modeling Surface Water Contamination One of the resources required for an ecosystem to function is an available source of fresh water This is quite true for human settlements as well If you examine the pattern of development you will nd a strong in uence exerted by the availability of fresh water While fresh water is usually abundantly available in the locations Where people tend to settle there is also an unfortunate tendency for development to cause the contamination of that same fresh water source Surface water contamination through a variety of types of pollution results in reduced water quality David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Types of Water Pollution We can classify types of pollution in a few different ways Source We can distinguish between point source pollution where the origin of the material can be identi ed and measures can be taken and nonpoint source pollution where there is no singular source of the pollution usually because the material originates throughout the landscape Ecological Impacts We can group pollutants based on how they effect the ecosystem eg pollutants that lower dissolved oxygen content vs pollutants that mimic estrogenic compounds etc Types of Water Pollution General Type We can group pollutants based on 1 the nature of the material or energy in question Heat thermal pollution As we heat the water either by returning heated water to the system directly or indirectly the solubility of dissolved oxygen in the water is decreased Silt amp Sediment Erosion of soils from a variety of activities increases turbidity which decreases light penetration decreasing photosynthesis in aquatic plants which lowers the dissolved oxygen content Nutrients Through careless fertilizer use increased N and P can boost algal growth again blocking light penetration etc David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Types of Water Pollution Organic Wastes When we add organic material to wastewater ef uent it can decompose in the water and reduce dissolved oxygen content Microorganisms Also associated with organic material these can transmit infectious disease Acids Whether through acid precipitation or industrial ef uent including mining by changing the pH of surface waters we can create conditions where some key organisms in an ecosystem cannot survive Various chemicals Any number of toxic compounds such as heavy metals organochloranes etc sources from pesticides and industrial discharges can be damaging to organisms David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Dissolved Oxygen The concentration of dissolved oxygen D0 in fresh water is a particularly important criterion of water quality because most aquatic life depends on a certain amount of oxygen being present A few processes can reduce the DO content of water Dumping organic waste in the water provides organic carbon compounds in the presence of DO and various decomposers thus organic waste 02 9 CO2 H20 various compounds Aquatic plants photosynthesize and provide the DO but excessive algal growth due to nutrients slows this Some aquatic organisms use the DO eg sh etc David Tenenbaum r GEOG 110 r UNCCH Fall 2005 Dissolved Oxygen 0 We can model DO and CO2 in an aquatic environment using the following schematic Atmospheric Oz and so I 01 Aqualic dissolved 01 and col Aquatic Plants FIGURE 51 Inflows and outflows of oxygen in an aquatic environment mmr i ll rmc c mzms Henry 5 Law In order to model the dissolved oxygen content in an aquatic ecosystem we rst need to understand the physical law that determines how much dissolved oxygen the water can hold The amount of DO that water can hold is a function of Henry s constant and partial pressures based on Henry s Law Co 2K02Poz 2 Where C02 is the concentration of D0 in H20 mgL P02 is the partial pressure of 02 at the atmosphere water boundary atm K0 is Henry s Constant which varies inversely with temperature mgLatm David Tenenbaum r GEOG 110 r UNCCH Fall 2005 2 Henry 5 Law Henry s Constant can be determined for any gasliquid interface through experiments We nd that for water and oxygen Henry s Constant becomes larger as the temperature drops eg At 5 degrees Celsius KO2 612 mgLatm At 20 degrees Celsius KO2 402 mgLatm We can use Henry s Law to calculate the maximum amount of DO called DOsat that water can contain at a given temperature and standard pressure 1 atm Since 02 comprises approximately 21 of the gases in the atmosphere the partial pressure of oxygen in the atmosphere is thus 021 atm David Tenenbaum r GEOG 110 r UNCCH Fall 2005 Henry s Law C02 KO2 P02 At 5 degrees Celsius using KO2 612 mgLatm C02 612 mgLatm 021 atm 129 mgL At 20 degrees Celsius using KO2 402 mgLatm C02 402 mgLatm 021 atm 84 mgL You can see this phenomenon of warmer water having a lower DO concentration manifesting itself in the summer when sh come up to the surface on very hot days to gain access to the slightly more oxygenrich water near the very surface There is so little oxygen in the warm water that fish will take the risk of coming closer to surface David Tenenbaum r GEOG 110 r UNCCH Fall 2005 Biochemical Oxygen Demand From our previous listing of processes that diminish the D0 in an aquatic system we know that adding organic waste can reduce DO levels through the decomposition of that waste The amount of oxygen required to decompose a certain amount of waste is its biochemical oxygen demand BOD and like D0 is measured in concentration units such as mgL BOD is a useful way to describe the general water quality of a sample because it indirectly measures the amount of organic waste present in the water Ultimate BOD BODult is used to describe the total amount of DO required to oxidize all the organic waste all 2005 Modeling Surface Water Contamination A municipal wastewater treatment facility is planning to locate upstream on a popular shing river The wastewater facility will continuously discharge wastewater into the river The ef uent will have have high biochemical oxygen demand BOD and low dissolved oxygen DO concentrations We want to determine the impact of the ef uent on the DO concentration of the river and ultimately the sh population in the river We also want to evaluate the potential impact of corrective measures the facility can take to address potential DO problems David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 89939993 31 Flows in this System Objective Predict DO levels in the river when organic waste is added from the treatment plant What pieces of information do we need to do this We need all the in ows and out ows of 02 DO of river water before organic waste is added DO of ef uent containing organic waste BOD of river water before organic waste is added BOD of ef uent containing organic waste Volume of river ow before ef uent is added Volume of ef uent ow The DO ef uent sat level of the river before mixing with the David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Processes and Model Structure We will model the resulting DO concentration in the river using a twostep approach 1 We will establish initial values of DO and BOD immediately after the river water and ef uent are mixed using a massbalance approach 2 We will predict the expected downstream DO levels taking into account some processes that will occur as the water moves downstream that change the DO Reoxygenation or aeration will absorb 02 from the atmosphere as the water moves downstream Deoxygenation will consume D0 in the river through the consumption of the organic waste David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Initial Stage River and Ef uent Mixing We will begin by assuming that the river water and ef uent mix uniformly throughout the original body of water this is the uniform mixing assumption The total mass of the the DO after mixing is equal to the sum of the masses of the D0 in the river and in the ef uent ie there is conservation of mass making the massbalance assumption a reasonable one We can calculate the D0 of the mixed water using a massbalance equation DOSVS DOpr DOaVS VP DOC DOSVS DOpr VS VP Initial Stage River and Ef uent Mixing DOa DOSVS DOpr VS VP where D0 is the DO conc in the mixed water mgL DOS is the DO conc in the river water mgL V is the volume of river water before mixing L D0 is the dissolved oxygen concentration in the ef uent mgL V is the volume of ef uent L For owing water we can use ow rates Q in L sec instead of volumes yielding D001 2 10st DOpr Q Q We can apply the very same massbalance principles to calculate the BOD values immediately after mixing the river water and the ef uent David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Downstream DO Levels Out ows As the mixed water containing newly added organic waste from the ef uent ows downstream decomposition of the waste will begin to occur rapidly The more organic waste was added the bigger the BOD and the easier it will be for microbes in the water to nd organic waste to decompose and decrease the BOD which we can model using BODWQ leODt or in STELLA terms a typical exponential model structure BUD k1 is known as the deoxygenation coef cient and has units of inverse a B out 1 Egg t1meeg days David Tenenbaum r GEOG 110 r UNCCH Fall 2005 Downstream DO Levels Out ows As the waste is consumed and the BOD is reduced the D0 is reduced at the same rate DOouzU leODO or in STELLA terms we must de ne the out ow from the DO reservoir to be identical to that from the BOD reservoir using this model structure BIIIEI n f my an o I E f Deoxygenation Downstream DO Levels In ows While D0 is being consumed through organic waste being decomposed it is also added back to the water through the reoxygenation process The rate at which reoxygenation occurs is a fx of how much more oxygen the water could theoretically hold ie how far from DOsat is the water or what is the water s oxygen de cit DOsat DO If the oxygen de cit is large the water can rapidly absorb oxygen from the atmosphere whereas if it is small atmospheric oxygen will be absorbed slowly according to the following equation Dome kziDOm r Dow Downstream DO Levels In ows DOmO k2DOsat t D003 k2 is the reoxygenation coef cient also measured in inverse time units eg dayS39l and varies according to surface water exposure to the atmosphere eg whitewater vs stagnant water and does not account for photosynthesis In STELLA terms BUD a BUDnut Wag w k1 on a i i c He yge an I Deoxygenation H2 EIUsat xquot David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005 Downstream DO Levels In ows We can also take into account that BOD is increased naturally in the river when organic matter ows into the system which we will model as occurring at a constant rate BODmQ A In STELLA terms m Boom QR BUDom hh wi f k1 on f HER eg E a Re yge El nquot Demcygenation U L It 00531 David Tenenbaum 7 GEOG 110 r UNCCH Fall 2005


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."

Anthony Lee UC Santa Barbara

"I bought an awesome study guide, which helped me get an A in my Math 34B class this quarter!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.