Water Quality Sampling
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Transcript of Water Quality Sampling
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WATER QUALITY SAMPLING
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WATER QUALITY
Water quality refers to the chemical, physical andbiological characteristics of water. It is a measure of
the condition of water relative to the requirements of
one or more biotic species and or to any human need
or purpose. It is most frequently used by reference to aset of standards against which compliance can be
assessed. The most common standards used to
assess water quality relate to health of ecosystems,
safety of human contact and drinking water.
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In the water industry:
Water Sampling and Analysis ensures water is of aquality and standard appropriate to its use and
determines the treatment processes required to ensurethe supply of safe water
The accuracy of water analysis is dependent on thesampling method used, the time elapsed betweensampling and analysis, the techniques used in laboratory
analysis and interpretation of the results. There are alsostandards governing water sampling frequency andtechniques/methodology used.
In the setting of standards, agencies make political and
technical/scientific decisions about how the water will beused. In the case of natural water bodies, they alsomake some reasonable estimate of pristine conditions.Different uses raise different concerns and thereforedifferent standards are considered. Natural water bodies
will vary in response to environmental conditions.
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CATEGORIES
THE PARAMETERS FOR WATER QUALITY ARE DETERMINED BY
THE INTENDED USE. WORK IN THE AREA OF WATER QUALITY
TENDS TO BE FOCUSED ON WATER THAT IS TREATED FOR HUMANCONSUMPTION, INDUSTRIAL USE, OR IN THE ENVIRONMENT.
Human consumption
Contaminants that may be in untreated water
include microorganisms such as viruses and bacteria;inorganic contaminants suchas salts and metals; organic chemical contaminantsfrom industrial processes and petroleumuse; pesticides and herbicides; and radioactive
contaminants. Water quality depends on the localgeology and ecosystem, as well as human uses suchas sewage dispersion, industrial pollution, use of waterbodies as a heat sink, and overuse (which may lowerthe level of the water).
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INDUSTRIAL AND DOMESTIC USEDissolved minerals may affect suitability of water for a range
of industrial and domestic purposes. The most familiar of
these is probably the presence of ions of calcium and
magnesium which interfere with the cleaning action of soap,
and can form hard sulfate and soft carbonate deposits inwater heaters or boilers. Hard water may be softened to
remove these ions. Hard water may be preferable to soft
water for human consumption, since health problems have
been associated with excess sodium and with calcium and
magnesium deficiencies. Softening decreases nutrition and
may increase cleaning effectiveness.
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ENVIRONMENTAL WATER QUALITY
Environmental water quality, also called ambient water
quality, relates to water bodies such as lakes, rivers, and oceans.
Water quality standards for surface waters vary significantly due to
different environmental conditions, ecosystems, and intended
human uses. Toxic substances and high populations of certain
microorganisms can present a health hazard for non-drinking
purposes such as irrigation, swimming, fishing, rafting, boating, and
industrial uses. These conditions may also affect wildlife, which use
the water for drinking or as a habitat.
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There is some desire among the public to return waterbodies to pristine, or pre-industrial conditions. Mostcurrent environmental laws focus on the designation ofparticular uses of a water body. In some countries thesedesignations allow for some water contamination as long
as the particular type of contamination is not harmful tothe designated uses. Given the landscape changes inthe watersheds of many freshwater bodies, returning topristine conditions would be a significant challenge. Inthese cases, environmental scientists focus on achieving
goals for maintaining healthy ecosystems and mayconcentrate on the protection of populationsof endangered species and protecting human health.
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SAMPLING AND MEASUREMENT
The complexity of water quality as a subject isreflected in the many types of measurements ofwater quality indicators. The most accuratemeasurements of water quality are made on-site,because water exists in equilibrium with itssurroundings. Measurements commonly made on-site and in direct contact with the water source in
question include temperature, pH, dissolvedoxygen, conductivity, oxygen reduction potential(ORP), pH, etc.
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WATER QUALITY EQUIPMENTS AND SAMPLING
PROCEDURES
Equipment and sampling for water quality arehighly specialized.
Special procedures are required for samples to
be analyzed for heavy metals or trace organicsto avoid contamination, oxidation, or adsorptionto the sampling equipment.
The U.S. Geological Survey has published a
series of manuals dealing with sampling andanalysis procedures for storm-water runoff,receiving water, and groundwater.
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An automated sampling station installed
along the East Branch Milwaukee
River,New Fane, Wisconsin. The cover of
the 24-bottle autosampler (center) is
partially raised, showing the samplebottles inside. The autosampler was
programmed to collect samples at time
intervals, or proportionate to flow over a
specified period. The data logger (white
cabinet) recorded temperature, specific
conductance, and dissolved oxygenlevels.
A rosette sampleris used to
collect samples in deep water,
such as the Great Lakes or
oceans, for water quality testing.
http://en.wikipedia.org/wiki/File:WQ_sampling_station_USGS_2004.jpghttp://en.wikipedia.org/wiki/File:WQ_sampling_station_USGS_2004.jpghttp://en.wikipedia.org/wiki/File:Rosette_sampler_EPA.gif -
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A gas chromatograph-
mass
spectrometermeasures pesticid
esand other organic polluants
An electrical conductivity
meter is used to
measure total dissolvedsolids
http://en.wikipedia.org/wiki/File:Electrical_conductivity_meter.jpghttp://en.wikipedia.org/wiki/File:GCMS_open.jpg