Lab 10: Contaminated water and remediation
Water on and in the Earth
Where is Earth's water located and in what forms does it exist? You can see how water is distributed by viewing these bar
charts. The left-side bar shows where the water on Earth exists; about 97 percent of all water is in the oceans. The middle
bar shows the distribution of that three percent of all Earth's water that is freshwater. The majority, about 69 percent, is
locked up in glaciers and icecaps, mainly in Greenland and Antarctica. You might be surprised that of the remaining
freshwater, almost all of it is below your feet, as groundwater. No matter where on Earth you are standing, chances are
that, at some depth, the ground below you is saturated with water. Of all the freshwater on Earth, only about 0.3 percent is
contained in rivers and lakes—yet rivers and lakes are not only the water we are most familiar with, it is also where most
of the water we use in our everyday lives exists.
How much of Earth's water is available for our uses ... and in what forms does it exist? You can best see how water is
distributed by viewing the pie charts. The top pie chart shows that over 99 percent of all water (oceans, seas, ice, most
saline water, and atmospheric water) is not available for our uses. And even of the remaining fraction of one percent (the
small brown slice in the top pie chart), much of that is out of reach. Considering that most of the water we use in everyday
life comes from rivers (the small dark blue slice in the bottom pie chart), you'll see we generally only make use of a tiny
portion of the available water supplies. The bottom pie shows that the vast majority of the fresh water available for our
uses is stored in the ground (the large grey slice in the second pie chart).
For a detailed explanation of where Earth's water is, look at the data table below. Notice how of the world's total water
supply of about 332.5 million cubic miles (1,386 million cubic kilometers) of water, over 96 percent is saline. And, of the
total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Thus,
surface-water sources (such as rivers) only constitute about 22,300 cubic miles (93,100 cubic kilometers), which is about
0.0067 percent of total water, yet rivers are the source of most of the water people use.
One estimate of global water distribution:
Water volume, in
cubic miles
Water volume, in cubic
kilometers
Percent of
fresh water
Percent of
total water
Oceans, Seas, & Bays
321,000,000
1,338,000,000
--
96.5
Ice caps, Glaciers, &
Permanent Snow
5,773,000
24,064,000
68.7
1.74
Groundwater
5,614,000
23,400,000
--
1.7
Fresh
2,526,000
10,530,000
30.1
0.76
Saline
3,088,000
12,870,000
--
0.94
Soil Moisture
3,959
16,500
0.05
0.001
Ground Ice & Permafrost
71,970
300,000
0.86
0.022
Lakes
42,320
176,400
--
0.013
Fresh
21,830
91,000
0.26
0.007
Saline
20,490
85,400
--
0.006
Atmosphere
3,095
12,900
0.04
0.001
Swamp Water
2,752
11,470
0.03
0.0008
Rivers
509
2,120
0.006
0.0002
Biological Water
269
1,120
0.003
0.0001
332,500,000
1,386,000,000
-
100
Water source
Total
Source: Gleick, P. H., 1996: Water resources. In Encyclopedia of Climate and Weather, ed. by S. H.
Schneider, Oxford University Press, New York, vol. 2, pp.817-823.
Water pollution is a large set of adverse effects upon water bodies such as lakes, rivers, oceans, and groundwater caused
by human activities.
Although natural phenomena such as volcanic eruptions, algae blooms, storms, and earthquakes also cause major changes
in water quality and the ecological status of water, water is only called polluted when it is not able to be used for what one
wants it to be used for. Water pollution has many causes and characteristics. Increases in nutrient loading may lead to
eutrophication. Organic wastes such as sewage impose high oxygen demands on the receiving water leading to oxygen
depletion with potentially severe impacts on the whole eco-system. Industries discharge a variety of pollutants in their
wastewater including heavy metals, resin pellets, organic toxins, oils, nutrients, and solids. Discharges can also have
thermal effects, especially those from power stations, and these too reduce the available oxygen. Silt-bearing runoff from
many activities including construction sites, deforestation and agriculture can inhibit the penetration of sunlight through
the water column, photosynthesis and causing blanketing of the lake or river bed, in turn damaging ecological systems.
Pollutants in water include a wide spectrum of chemicalpathogen, and physical chemistry or sensory changes. Many of the
chemical substances are toxic. Pathogens can produce waterborne diseases in either human or animal hosts. Alteration of
water's physical chemistry include acidity, electrical conductivity, temperature, and eutrophication. Eutrophication is the
fertilization of surface water by nutrients that were previously scarce. Even many of the municipal water supplies in
developed countries can present health risks. Water pollution is a major problem in the global context. It has been
suggested that it is the leading worldwide cause of deaths and diseases, and that it accounts for the deaths of more than
14,000 people daily
Contaminants
Contaminants may include organic and inorganic substances.
Some organic water pollutants are:
Insecticides and herbicides, a huge range of organohalide and other chemicals
Bacteria, often is from sewage or livestock operations
Food processing waste, including pathogens
Tree and brush debris from logging operations
VOCs (volatile organic compounds), such as industrial solvents, from improper storage
DNAPLs (dense non-aqueous phase liquids), such as chlorinated solvents, which may fall at the bottom of
reservoirs, since they don't mix well with water and are more dense
Petroleum Hydrocarbons including fuels (gasoline, diesel, jet fuels, and fuel oils) and lubricants (motor oil) from
oil field operations, refineries, pipelines, retail service station's underground storage tanks, and transfer
operations. Note: VOCs include gasoline-range hydrocarbons.
Detergents
Various chemical compounds found in personal hygiene and cosmetic products
Disinfection by-products (DBPs) found in chemically disinfected drinking water
Some inorganic water pollutants include:
Heavy metals including acid mine drainage
Acidity caused by industrial discharges (especially sulfur dioxide from power plants)
Pre-production industrial raw resin pellets, an industrial pollutant
Chemical waste as industrial by products
Fertilizers, in runoff from agriculture including nitrates and phosphates
Silt in surface runoff from construction sites, logging, slash and burn practices or land clearing sites
Transport and chemical reactions of water pollutants
Most water pollutants are eventually carried by the rivers into the oceans. In some areas of the world the influence can be
traced hundred miles from the mouth by studies using hydrology transport models. Advanced computer models such as
SWMM or the DSSAM Model have been used in many locations worldwide to examine the fate of pollutants in aquatic
systems. Indicator filter feeding species such as copepods have also been used to study pollutant fates in the New York
Bight, for example. The highest toxin loads are not directly at the mouth of the Hudson River, but 100 kilometers south,
since several days are required for incorporation into planktonic tissue. The Hudson discharge flows south along the coast
due to coriolis force. Further south then are areas of oxygen depletion, caused by chemicals using up oxygen and by algae
blooms, caused by excess nutrients from algal cell death and decomposition. Fish and shellfish kills have been reported,
because toxins climb the foodchain after small fish consume copepods, then large fish eat smaller fish, etc. Each
successive step up the food chain causes a stepwise concentration of pollutants such as heavy metals (e.g. mercury) and
persistent organic pollutants such as DDT. This is known as biomagnification which is occasionally used interchangeably
with bioaccumulation.
The big gyres in the oceans trap floating plastic debris. The North Pacific Gyre for example has collected the so-called
"Great Pacific Garbage Patch" that is now estimated at two times the size of Texas. Many of these long-lasting pieces
wind up in the stomachs of marine birds and animals. This results in obstruction of digestive pathways which leads to
reduced appetite or even starvation.
Many chemicals undergo reactive decay or chemically change especially over long periods of time in groundwater
reservoirs. A noteworthy class of such chemicals are the chlorinated hydrocarbons such as trichloroethylene (used in
industrial metal degreasing and electronics manufacturing) and tetrachloroethylene used in the dry cleaning industry (note
latest advances in liquid carbon dioxide in dry cleaning that avoids all use of chemicals). Both of these chemicals, which
are carcinogens themselves, undergo partial decomposition reactions, leading to new hazardous chemicals (including
dichloroethylene and vinyl chloride).
Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great
distances through unseen aquifers. Non-porous aquifers such as clays partially purify water of bacteria by simple filtration
(adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity: however, in some
cases, the pollutants merely transform to soil contaminants. Groundwater that moves through cracks and caverns is not
filtered and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use
natural sinkholes as dumps in areas of Karst topography.
There are a variety of secondary effects stemming not from the original pollutant, but a derivative condition. Some of
these secondary impacts are:
Silt bearing surface runoff from can inhibit the penetration of sunlight through the water column, hampering
photosynthesis in aquatic plants.
Thermal pollution can induce fish kills and invasion by new thermophilic species. This can cause further
problems to existing wildlife.
Wastewater must pass through numerous systems before being returned to the environment. Here is a partial listing from
one particular plant system:
Barscreens - Barscreens remove large solids that are sent into a grinder. All solids are then dumped into a sewer pipe
at a Treatment Plant.
Primary Settling Tanks - Readily settable and floatable solids are removed from the wastewater. These solids are
skimmed from the top and bottom of the tanks and sent to the Treatment Plant.
Secondary Treatment - The wastewater is cleaned through a biological treatment method that uses microorganisms,
bacteria which digest the sludge and reduce the nutrient content. Air bubbles up to keep the organisms suspended and
to supply oxygen to the aerobic bacteria so they can metabolize the food, convert it to energy, CO2, and water, and
reproduce more microorganisms. This helps to remove ammonia also through nitrification.
Secondary Settling Tanks - The force of the flow slows down as sewage enters these tanks, allowing the
microorganisms to settle to the bottom. As they settle, other small particles suspended in the water are picked up,
leaving behind clear wastewater. Some of the microorganisms that settle to the bottom are returned to the system to be
used again.
Tertiary Treatment - Deep-bed, single-media, gravity sand filters receive water from the secondary basins and filter
out the remaining solids. As this is the final process to remove solids, the water in these filters is almost completely
clear.
Chlorine Contact Tanks - Three chlorine contact tanks disinfect the water to decrease the risks associated with
discharging wastewater containing human pathogens. This step protects the quality of the waters that receive the
wastewater discharge.
One of two procedures is then followed according to the future disposal site:
1. Reclaimed Water Pump Station - The pump station distributes reclaimed water to users around the City. This
may include golf courses, agricultural uses, cooling towers, or in landfills.
2.
Water is passed through high level purification to be returned to the environment. Currently this means a reverse
osmosis system.
Procedure for using the colorimeter:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Step 3
Plug in the power cord of the instrument.
Set the absorption wavelength to 680 nm.
Press the power switch.
Insert the reference sample (distilled water)
Press the reference button.
Insert the first sample with the non-corrugated side facing towards the screen.
Press the green sample button
Record the absorption number.
Continue with 6 and 7 for each remaining sample.
Step 4
step 5
step 7
This instrument measures the absorption, thus, it detects when absorption is taking place in a sample. Absorption can
be caused by disseminated solids but also by dissolved compounds that absorb certain parts of the visible spectrum.
Polluted Water Lab
This lab deals with a small region in Upper-Lower Slobovia. This is the site of several small businesses, which, for the
most part, thrived until recently. Karen Marchal’s Mica Analysis Lab used to produce the world’s most accurate mica analyses data, but recently all her data has shown weird results . The guinea pigs at Falster’s Airborne Guinea Pig Ranch
have lost all desire to perform their shows. The owner is currently under medical care due to intense mental anguish.
The students at Drew Boudreaux’s Center for the Geologically Disabled have not noticed any problems, nor have the
employees at Sarwar’s Bengali Poetry Press. You are a consultant hoping to identify the cause of the recent problems and water pollution is strongly suspected as
each location is obtaining water from wells on the properties. In the area, you see all sorts of potential trouble spots.
The abandoned quarry to the NW may house oil-based lubricants and fuels, possibly in rusty, leaking containers,
Downhill, the waste oil recycling plant poses similar hazards. The township dump to the north could be the source of all
sorts of problematic compounds, especially if the foundation of the dump is not sealed. The radio tower may house
PCBs in the equipment which after time may seep and escape. Sarwar’s Bengali Poetry Press may use materials in a
careless fashion and release them into the environment.
You collected 16 water samples for this investigation. After calibration with the standard sample, measure and record
the absorption rate of each sample. Plot the data on the map of sampling locations, and answer the corresponding
question.
Location #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Absorption rate
↑north ---------- 100 m
Use this section to contour your data.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Is there any evidence from where any pollution may originate from? Why is Boudreaux’s property seemingly unaffected?
Additional questions:
Groundwater accounts to how much of the world’s total water (fresh and saline waters)?
How are germs in tap water removed?
What do you think is the pore size of those ceramic filters that hikers buy? They filter out even very small germs.
To purify water, why don’t we just distill the waste water? All solids would be left behind. What are two major drawbacks to this method?
Other methods used to purify water, especially to desalinate water in desert regions, do exist. Why do you think such
methods are not more commonly utilized?
Slightly saline ground water like it occurs in the American SW in a number of regions is used there for irrigation. What
do you think happens to the salt that is dissolved in this water? Consider the fact that rainfall in those regions is sparse,
that is why irrigation is needed in the first place.
You probably heard of the food chain, and if not, it essentially says that ‘the bigger guy eats the little guy’. If these animals live in slightly polluted water and assume that the pollutant has a tendency to end up in fatty tissue, what is
your prediction for the continued welfare of the ‘bigger guy’? Even such seemingly harmless compounds as laundry soap can influence the environment in a negative aspect. In the
1950-1970s, phosphate-containing laundry soap was widely used. It ended up in rivers and streams and caused rapid
algal growth and then collapse of the algal growth and eutrophication (extensive using up of dissolved oxygen in the
water and widespread fish kill. Are we still using phosphate-based laundry compounds now?