LITERATURE REVIEW
Water pollution is a major environmental problem that occurs in many
surface and ground water sources. It can be characterised in the form of
chemical, physical and biological pollution. Chemical pollution includes things
such as toxic metals, inorganic compounds such as phosphates and nitrates,
acidic waters from mining activities and industry pharmaceuticals and many
other chemical compounds from industries and wastewater treatment plants.
Whereas, physical pollution includes sediment pollution, trash thrown in water
bodies, thermal and other suspended loads. In addition, biological pollution
refers to pathogenic bacteria, viruses, and parasitic protozoa. Common
pathogenic microbes introduced into natural water bodies are pathogens from
untreated sewage or surface runoff from intensive livestock grazing.
Water can be contaminated naturally by both geological or meteorological
events and by anthropogenic means. Human sources of contamination can be
classified as either point source or nonpoint source. Point source pollution is
defined as any contaminant that enters the environment from an easily identified
and confined place. Examples include sewage-outflow pipes, drainage ditches
and smokestacks. Non point sources are the opposite of point source pollution,
with pollutants released in a wide land area and not from one specific location.
Examples include agricultural runoff and urban stormwater runoff. It occurs
when rainwater, snowmelt, or irrigation washes off ploughed fields, city streets,
or suburban backyards and carries pollutants into the water sources. As this
runoff moves across the land surface, it picks up soil particles and pollutants,
such as nutrients, metals and pesticides.
Water quality is a term that expresses the suitability of water to
sustain various uses or processes. It can be expressed in terms of the
concentration and state of some or all of the organic and inorganic
materials present in the water, together with certain physical characteristics
of the water. In order to determine the quality of water, scientists measure
a variety of properties. These properties include temperature, acidity (pH),
dissolved solids, particulate matter (turbidity), dissolved oxygen, hardness
and suspended sediment. Each parameter has an environmental
management limit that sets a maximum or minimum standard used as a
benchmark of indication to determine whether the quality of water is good
or bad.
Mitchell, H. (n.d.). “Chapter 8 - Water Quality” in “Introduction to
Environmental Science” on OpenALG. OpenALG. Retrieved March 13, 2022,
from
https://alg.manifoldapp.org/read/introduction-to-environmental-science/section/
acc4e077-c8d0-47c7-a92c-c639e4071d14
Turbidity is the amount of cloudiness in water. High levels of turbidity
can occur as a result of higher concentrations of silt, clay, and organic materials.
It can vary from a river full of mud and silt where it would be impossible to see
through the water to a spring water which appears to be completely clear (low
turbidity). A Secchi Disk is a simple way to measure turbidity. The Secchi disk
is lowered into the water until it is no longer visible, and that depth is measured.
Secchi depth values that are high indicate clearer water, and low Secchi depths
indicate high turbidity.
Three Main Types of Water Quality Parameters Explained. (2021, September
20). Sensorex. Retrieved March 13, 2022, from
https://sensorex.com/2021/09/20/three-main-types-of-water-quality-parametersexplained/
Dissolved Oxygen is the amount of oxygen dissolved in water. Oxygen
gets into water by diffusing within the surrounding air, aeration and as a waste
product from plants through photosynthesis. Biological oxygen demand directly
affects the amount of dissolved oxygen in rivers and streams. The rate of
oxygen consumption is affected by variables such as temperature, pH, the
presence of certain kinds of microorganisms, and the type of organic and
inorganic material in the water. The amount of dissolved oxygen in the water
dictates how polluted the water sample is. Low amounts of dissolved oxygen
indicate that the water is highly polluted and that organic contaminants are
consuming the dissolved oxygen. The concentration of dissolved oxygen is
inversely related to the temperature of water. Cold water holds more dissolved
oxygen than warm water. The environmental management limit for dissolved
oxygen is less than 4. Whereas the environmental management limit for
temperature is 40 for coastal nearshore and 45 for marine offshore.
Biochemical Oxygen Demand - BOD testing and measurement in water. (n.d.).
YSI. Retrieved March 13, 2022, from
https://www.ysi.com/parameters/biochemical-oxygen-demand-bod
Phosphates are chemicals containing the element phosphorus which affect
water quality by causing excessive growth of algae and eventually
eutrophication. Excessive amounts of algae clouds the water in an effect called
an algal bloom, which reduces the sunlight available to other plants and
sometimes kills them. When the algae die, the bacteria that break them down
use up dissolved oxygen in the water, depriving and sometimes suffocating
other aquatic life. Phosphates enter waterways from human and animal waste,
phosphorus-rich bedrock, laundry and cleaning wastewater, industrial effluents,
and fertiliser runoff. The Environmehnt management limit for phosphates in
water is 0,02 ppm.
Green, J. (2018, August 6). How Do Phosphates Affect Water Quality?
Sciencing. Retrieved March 13, 2022, from
https://sciencing.com/phosphates-affect-water-quality-4565075.html