Common Water Measurement

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22 Φεβ 2014 (πριν από 3 χρόνια και 5 μήνες)

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Common Water Measurement

1.
Temperature

2.
pH

3.
Specific
conductance/Total
Dissolved Solids

4.
Hardness/Mineral Content

5.
Turbidity/Suspended Sediment

6.
Salinity/Buoyancy

7.
Dissolved
Gasses: Oxygen,
Carbon Dioxide,
Nitrogen


8.
Plant Nutrients: Oxygen Cycle;
Carbon Cycle; Nitrogen Cycle;
Phosphorus

9.
Bacteria


What components of a water environment can we change to
increase or decrease the number of organisms that can exist in it
?

CWM Objectives:


The student should be able to:


Explain what specific conductance is and what
factors influence


Understand what TDS means and why we study it


Compare mineral content to water hardness, and
analyze water hardness effect on detergent
performance (lathering)


Explain how suspended solids relate to turbidity




Term
: Specific Conductance




1 5

What it means to me:


1.
A measure of the ability of water to
conduct an electrical current. (Electrical

Conductivity = EC
)


2.
highly dependent on the amount of total
dissolved solids (TDS) in the water.




Examples:


1.
Pure water, such as distilled water, will
have a very low specific conductance,
and sea water will have a high specific
conductance


2.
High TDS = High specific conductance


3.
High dissolved
-
solids concentration
can cause deterioration of plumbing
fixtures and appliances, scale

build
-
up,

and
unpleasant taste or odor

of
drinking water.

My understanding: 1=No 5=Yes



Total Dissolved Solids (TDS)


TDS

is a measure of the combined content of all
inorganic

and
organic

substances contained in a liquid


Total dissolved solids are normally discussed only for
freshwater systems, as salinity comprises some of the ions
constituting the definition of TDS.



The principal application of TDS is in the study of
water
quality

for
streams
,
rivers

and
lakes


TDS is not generally considered a primary pollutant


it is not deemed to be associated with health effects


It is used as an indication of aesthetic characteristics of
drinking water

and as an aggregate indicator of the
presence of a broad array of chemical contaminants.


Term:
Hardness





1 5

What it means to me:



Hard water is water that has high mineral
content (in contrast with soft water).


Rainwater and distilled water are soft,
because they also contain few ions.
[




Hard water minerals primarily consist of
calcium (Ca2+), and magnesium (Mg2+)
metal
cations
, and sometimes other
dissolved compounds such as bicarbonates
and sulfates.




Examples:



The simplest way to determine the
hardness of water is the lather/froth
test:


soap or toothpaste, when
agitated, lathers easily in soft
water but not in hard water.



These ions enter a water supply by
leaching from minerals within an
aquifer



Soft Water
vs

Hard Water


The
World Health Organization

says that
"there does not appear to be any
convincing evidence that water
hardness causes adverse health effects
in humans."
[

My understanding: 1=No 5=Yes



Hardness can be quantified by
instrumental analysis.


Reported in parts per million (ppm) or mass/volume (mg/L)


U
sually measures only the total concentrations of calcium and magnesium, the two most prevalent
divalent metal ions.


iron
,
aluminium
, and
manganese

can also be present at elevated levels in some locations.


The presence of iron characteristically confers a brownish (rust
-
like)
colour

to the calcification, instead of white (the color of most of the other compounds).


A

mixture of minerals dissolved in the water, together with the water's
pH

and
temperature
, that
determines the behavior of the hardness



Descriptions of hardness correspond roughly with ranges of mineral concentrations:


Soft:


0

60 mg/L



Moderately hard:


61

120 mg/L



Hard:



121

180 mg/L



Very hard:


≥181 mg/L


Water hardness varies throughout the United States.


Term:
Suspended Sediment




1 5

What it means to me:


Solid particles transported in a fluid media or found
in deposit after transportation by flowing
water, wind, glacier and gravitational action.


Their concentration in a water body is affected by
many factors.


Negative

Effects of S.S.:




transport adsorbed toxic substances


They block light from reaching submerged
vegetation, which in turn slows down
photosynthesis


suspended solids absorb heat from sunlight,
increasing the water temperature, decreasing
the dissolved oxygen level even more.




Examples:


In
rivers
, the concentration depends on the
water’s flow rate, turbidity, soil erosion,
urban runoff, and wastewater and septic
system effluent


In
lakes
, the concentration depends on
decaying plants and animals, bottom
-
feeding fish, and wind/wave action play a
larger role




Suspended particles can transport heavy

metal and other toxic substances into
aquatic habitats


This effect causes less dissolved oxygen to be
released into the water by the plants and
in extreme cases, results in death of the
plants.


My understanding: 1=No 5=Yes



Term:
Suspended Sediment




1 5

What it means to me:


When it rains, soil and debris from the
surrounding land are eroded and washed into
streams.


Sediment particles from as small as clay to as
large as boulders flow along with the water.



Fast
-
moving water can pick up, suspend, and
move larger particles more easily than slow
-
moving waters.



This is why rivers are more muddy
-
looking during storms
--

they are carrying
a
LOT

more sediment than they carry
during a low
-
flow period.



In fact, so much sediment is carried
during storms that well over one
-
half of
all the sediment moved during a year
might be transported during a single
storm period.


My understanding: 1=No 5=Yes



Term:
Suspended Sediment

So what does this have to do
with people?



1 5

On the
plus

side, sediment deposited on
the banks and flood plains of a river is
often mineral
-
rich and makes excellent
farmland.


On the
negative

side, when rivers flood, they
leave behind many tons of wet, sticky,
heavy, and smelly mud
--

not something
you would want in your basement.


Sediments can also harm dams and reservoirs.
When a river is dammed and a reservoir
is created, the sediments that used to
flow along with the relatively fast
-
moving river water are, instead,
deposited in the reservoir.



The Nile in Egypt and the Mississippi River here
in the United States are good examples.









This happens because the river water flowing
through the reservoir moves too slowly
to keep sediment suspended
--

the
sediment settles to the bottom of the
reservoir.

Reservoirs slowly fill up with sediment and
mud, eventually making them unusable
for their intended purposes.

My understanding: 1=No 5=Yes



Suspended sediments play a key role in shaping the
characteristics of a body of water; triggering changes in
morphology of an area.


As sedimentation and
resuspension

occur, particles are moved
to different areas, altering the depths of
waterbodies
.



Term:
Turbidity




1 5

What it means to me:


1.
Turbidity measures the scattering effect
that suspended solids have on light: the
higher the intensity of scattered light, the
higher the turbidity.


2.
the cloudiness or haziness of a fluid caused
by suspended particles


secchi

disk




Examples:


1.
Turbidity is measured by shining a light
through the water and is reported in
nephelometric

turbidity units (NTU).


2.
Material that causes water to be turbid
include:


clay


silt


finely divided organic and inorganic
matter


soluble colored organic compounds


plankton


microscopic organisms


My understanding: 1=No 5=Yes