1.0 Paleo limnologists now recognise that climate change,

1.0 Eutrophication

1.1 Introduction

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Eutrophication, is the
artificial enrichment of a water body or aquatic system with phosphorus and
nitrogen nutrients, usually with an excess amount of nutrients. This process
cause an excessive growth of plants and algae and due to the biomass load, may
result in oxygen depletion of the water body. For example, as a
response to increased levels of nutrients,  there is a great increase of phytoplankton which
is called algal bloom occurs in the water body .The
nutrients can be come from the animal wastes, fertilizers that are often used
in farming and sewage which are washed by rain or irrigation into the water
bodies through surface runoff. This will
increase the nutrient level and contribute to eutrophication. Eutrophication
can be divided into cultural eutrophication which is caused by human activity
and natural eutrophication which is a natural process.

     Cultural
eutrophication is the process that speeds up natural eutrophication because of
human activity. Due to clearing of land and building of towns and
cities, land runoff is accelerated and more nutrients such as phosphates and nitrate are supplied to lakes
and rivers, and then to coastal estuaries and bays. Extra
nutrients are also supplied by treatment plants, golf courses, fertilizers,
farms and  untreated sewage in many
countries.

 

     Natural eutrophication is a natural process.
Eutrophication occurs in many lakes in temperate grasslands. Paleo limnologists now
recognise that climate change, geology, and other external influences are
critical in regulating the natural productivity of lakes. Some lakes also demonstrate
the reverse process, becoming less nutrient rich with time. The main difference
between natural and anthropogenic eutrophication is that the natural process is
very slow, occurring on geological time scales.

 

 

 

 

 

1.2 Why it happens ?

    
Eutrophication is mainly caused by human action due to their dependence
on using fertilizers. Agricultural practices and the use of fertilizers on
lawns, golf courses and other fields contribute to phosphate and nitrate
nutrient accumulation. When the concentration of nutrients increases until the
ground is no longer able to assimilate them, the nutrients are carried by rain
into rivers and groundwater that flow into lakes or seas. The plankton, algae
and other aquatic plant life are then well fed and their photosynthesis
activity is increased. They grow and reproduce more rapidly, resulting in dense
growth of algal blooms and plant life. This will disrupt the normal ecosystem
functioning and causes many problems. (Refer
appendice-1)

    
On the other hand, eutrophication can be caused by the input of
untreated sewage as well as discharge from sewage treatment plants. We can see
that the sewage water is directly
discharged into water bodies such as rivers, lakes and oceans in various
parts of the world, especially
the developing nations. The result of this is the released of a high
quantity of  chemical nutrients which
stimulates the disproportionate growth of algae and other aquatic plants that threatens the survival
of aquatic life in many ways. Some countries may also treat the sewage water,
but still discharge it into water bodies after treatment. Although the water is
treated, but it can still cause the accumulation of excess nutrients and lead
to eutrophication. (Refer appendice-1)

     Besides
that, it is also caused by aquiculture.
Aquiculture is a technique of growing shellfish, fish and even
aquatic plants in water containing dissolved nutrients. Hence, the unconsumed
food particles together with the fish excretion can significantly increase the
levels of nitrogen and phosphorous in the water if aquiculture is not properly
managed. This will results in the dense growth of microscopic floating plants.    

    
Lastly, eutrophication may be caused by natural event such as floods and
the natural flow of rivers and streams. The excess nutrients will be washed off
from the land and flow into the water systems that causes the excessive growth
of algal blooms. Also, as lakes grow old, they naturally accumulate sediments such
as phosphorus and nitrogen nutrients which contribute to the explosive growth
of phytoplankton and cyanobacterial blooms.

1.3 How it happens ?

    
Firstly, the excess nutrients are applied to the soil. Then, they get
drained into the ponds, lakes, or rivers. This encourages the rapid growth of
photosynthesising organisms, especially algae. This results in a population
explosion known as algal bloom. The algal bloom blocks the light of the sun
from reaching the bottom of the water body. As a result, the aquatic plants
beneath the algal bloom die because they cannot get sunlight to photosynthesize
and this further decreases the supply of oxygen in water. Eventually, the algal
bloom dies and sinks to the bottom of the lake, decomposing microorganisms,
especially aerobic bacteria, grow rapidly and use up oxygen for respiration at
fast rate. The aerobic bacteria use up oxygen faster than it can be
replenished. This cause the biochemical oxygen demand (BOD) to increase
resulting in the depletion of oxygen in water. Due to the lower level of oxygen
concentrations, the larger life forms, such as fish, suffocate are not able to survive.
In extreme cases, if the oxygen level continue to drop until the water become
completely deoxygenated, aerobic bacteria will growth and releases toxic gases
that are harmful to aquatic life. This body of water can no longer support life
and this process is called eutrophication. (Refer
appendices-2)

 

1.4 Effects
of eutrophication with some examples

     For aquatic plants, they need two
essential nutrients to
grow such as nitrogen (N) and phosphorus (P). In a healthy lake, the
biochemical oxygen demand (BOD) must be low which indicates the better water
quality and the nutrients must occur in small amounts for the survival of
aquatic plants. Inversely, major water pollution problem
will results if the nutrients are in large quantities. Too many nutrients will
stimulate the rapid growth of plants and algae, clogging waterways and
sometimes creating a serious algal bloom. If the situation happens, the
survival of fish and other aquatic life forms will be threaten. The algal blooms that caused by the
excessive nutrients in the water body will limit the amount of dissolved oxygen
required for respiration by the aquatic life forms. When the algae and aquatic
plants die and decompose, it will encourage the growth of detritus and oxygen depletion
happens. When the dissolve oxygen reaches hypoxic levels, the animal and plant
species under the water such as shrimp, fish and other aquatic biota suffocate
will die. In extreme cases, the anaerobic conditions encourage the growth of
bacteria that produces toxins which are deadly to the marine mammals and birds.
The growth of phytoplankton also causes the light penetration into the water to
be reduced. This can bring about aquatic dead zones, loss of aquatic life and
it also lessens biodiversity.
(Refer appendices-3)

    
Furthermore, it results in the deterioration
of water quality and limited access to safe drinking water. This is because algal blooms are highly
toxic and once the water reaches the anaerobic conditions, the growth of more
toxic bacterial is promoted. Extensive deterioration of water quality and decline in the
availability of clean drinking water will be the consequence. Due to the dense
growth of algal blooms and photosynthetic bacteria in surface waters, the water
systems will be blocked and thus availability of piped water become limited. On
this regard, toxic algal blooms have shut down numerous water supply systems
across the globe. For example, in 2007, more than 2 million residents of Wuxi,
China could not access piped drinking water for more than a week due to severe
attack by algal blooms on Lake Taihu. (Refer appendices-4)

     Moreover,
it is poisoning which will cause
several negative impact on human health and animal
when ingested the water in drinking water. Even at very low concentrations, the cyanobacteria
which generates red tide will release very powerful toxins with high poison
levels in the water. Besides that, the toxic compound is doubled by the anaerobic
conditions which created by the explosive plant growth in the water. It is
harmful to humans and animals even at the least concentration when ingested in
drinking water. In addition, algal blooms can threaten livestock health. For
example, the first recorded incidence of animal poisoning from a blue–green
algal bloom was in Lake Alexandrina , Australia in the late 1800s. (Refer appendice-5) Cattle, horses, pigs, sheep and
dogs died after drinking water covered by a scum of the blue–green algae. The major
cause of deaths in animals is from liver poisoning and neurotoxicity that leads
to respiratory failure. This is because the toxic compounds can make their way
up the food chain, contributing to various negative health impacts such as
cancers. The shellfish accumulate the poison in their muscles and then poisons
humans upon consumption. Other than that, high nitrogen concentration in
drinking water will have negative effects on infants. For example, the infant will suffer blue baby syndrome. This is
because the drinking water with high nitrogen concentration is associated with the
ability of inhibiting blood circulation in infants. Hence, the baby will takes
on a bluish hue because of poorly oxygenated blood resulting in blue baby
syndrome.

    
Lastly, it endangers fishing. This is due to the increased
growth of floating plants such as algae and photosynthetic
bacteria which is the obstacle that limits the movement of boat to a location
and the fishing vessels. We will also have some difficulties to set the fishing
nets in water because of the accumulation of floating plants on the surface of
water.

 

1.5 Solutions for eutrophication

    
Eutrophication mainly arises from the use of nitrate and phosphate fertilizers. Hence, composting can be the effective solution
for eutrophication. This is because composting is a substitute for fertilizers.
It is a practice of converting organic matter
such as food residues and decaying vegetation into compost manure. Nutrients in
the compost manure do not contain the phosphorus and nitrates that cause algae
to bloom, so when there is run-off, it does not harm the quality of water. In
compost fertilizer, all the essential elements are broken down and synthesized
by the plants thereby not creating the cycle of eutrophication. This method of
controlling eutrophication is termed as nutrient limitation. (Refer appendices-6)

     Other than that, limiting pollution is an easy and effective method of cutting back on the amount of nitrogen and
phosphates discharged into water systems. Big manufacturing companies and
municipalities ought to reduce pollution and desist from discharging waste into
water systems to reduce the amount of toxins and nutrients ending up in the
waters that feed the algae and other microscopic organisms. If industries and
municipalities can cap their waste discharge and pollution to a lower level, then nutrient content is reduced
in the water systems which can subsequently control eutrophication.

     Last but not least, strengthening laws and
regulations against non-point water source pollution is also a solution that can substantially control eutrophication.
The amount of nutrients entering the aquatic ecosystems can essentially
lessening by minimizing non-point pollution. The laws should aim at enhancing
high water quality standards and zero-tolerance to non-point solution. With the
support of policymakers, citizens, pollution regulatory authorities and the
government, it is easy to control eutrophication.

2.0 Deforestation

2.1 Introduction

Deforestation
is the thinning or clearing of a forest or stand of trees. (Refer appendice-7) Deforestation is done by human
where the land is then used for agriculture and development. For
examples, the forestland or woodlands is converted to farms, ranches,
or urban use. Recent and present deforestation mainly
occurs in tropical rainforests.
About 30% of Earth’s land surface is covered by forests.

     Moreover,
deforestation on a major scale had been occurring in both developed and developing
countries since about 1700 when it is estimated that forests covered as much as
4.5 billion hectares of the planet. If this estimation is correct, total forest
cover has declined by about 1.0 billion heactares or 23% during last 300 years.
During war, deforestation has been used to deprive the enemy of vital resources and
cover for its forces. Modern examples of this were the use of Agent Orange by the British military in Malaya during the Malayan Emergency and the United States military in Vietnam
during the Vietnam War.
As of 2005, net deforestation rates have ceased to increase in countries with a
per capita GDP of
at least US$4,600. Deforested regions typically incur
significant adverse soil erosion and
frequently degrade into wasteland.

    
The problem of deforestation is become
more serious from years to years. According to the United Nations’ Food and
Agriculture Organization (FAO), an estimated 18 million acres (7.3 million
hectares) of forest, which is roughly the size of the country of Panama, are
lost each year. Besides, about half of the world’s tropical forests have
been cleared. On the other hand, according to the research, about 30% of the
world’s land mass can be found to be covered by the forests. Recently, forest
loss has contributed between 6% and 12% of annual global. Furthermore, World Wildlife Fund (WWF) found that about 36
football fields worth of trees lost every minute.

 

 

2.2 Causes of
deforestation

     There
are various factors that can caused deforestation. First of all, deforestation
can be caused by agriculture activities (Refer appendices-8). A
major cause of deforestation is agriculture plantations. Due to the increasing
populations, the demand for food products such as soybeans and palm oil
increases dramatically. This causes a large quantity of trees or forests are
cleared at an unnerving rate to grow crops and for cattle. In some extreme
situation, the farmers will clear a forest area until the soil is completely
degraded and then move to a new woodland to continue the process. The abandoned
land, will eventually reforest but it will take many years to return to its
original condition.

     Next, mining also results in deforestation
(Refer appendices-9). Deforestation occurs in Brazilian
Amazon particularly since the 1980s with miners often
clearing forest to open the mines (Refer
appendice-10). This require
considerable amount of woodlands. They often use them for building material,
collecting wood for fuel and subsistence agriculture. In addition, due to the
rising demand and high mineral prices, mining on tropical forests increases. These projects are
often accompanied by large infrastructure construction, such as roads,
railways, and power systems.
The
waste that comes out from mining pollutes the environment and affects the nearby
species.

     Lastly, logging is also contributed to
deforestation (Refer appendice-11). Logging is the process of
cutting and processing trees to produce timber and pulp to
supply the world’s markets for furniture, construction, paper, and
other products. Wood-based industries such as paper,
matchsticks, and furniture need a large quantity of wood. Cooking and heating
process required coal and lumber which can used as fuel for burning and half of
the illegal removal from forests is used as fuelwood. Large areas of forests
will be cleared to construct roads for the large trucks to enter the logging
sites. Logging is important to
regional economies and rural communities. However, if it is not managed
properly, it can contribute to deforestation and forest degradation. 

 

 

 

 

2.3 Effects of deforestation with examples

     One of the devastating effect that caused by
deforestation is the loss of animal and plant species due to the loss of their
habitat. Most of the animals and plants live in forest and many
cannot survive and caused the removal of the bases of numerous food webs. The
trees of the rainforest provide shelter for the species and provide canopy that
regulates the temperature. However, deforestation thins the
forest canopy which is meant to block sun rays during the day and holds in the
heat at night. This will lead to extreme condition. In conclusion, animals and
plants will began to extinct due to the loss of their habitat and extreme
temperature that are harmful to them. For example, Indonesia and Malaysia produce more than 85% of the world’s
palm oil and are the only remaining home to orangutans. Fewer than 80,000 of
these animals survive today, their habitats under constant threat of deforestation.

Apart from that, trees are
important in absorbing greenhouse gases that fuel global warming. If the trees
are cut, burned or removed, the amount of trees will reduced which means larger
amounts of greenhouse gases entering the atmosphere. It is found
that deforestation is responsible for around 20% of greenhouse
gas emissions and 1.5 billion tons of carbon is released every year by tropical
deforestation. Hence, deforestation can cause the increased of greenhouse gas emissions.

Furthermore,
deforestation can cause landslides, soil erosion, and flash floods. Without a
proper planning and development, a land stripped of its vegetations is subject
to soil erosion. This is because the trees are used to retain water and
topsoil, if there are no
plant root systems, it will cause the soil structure become unstable. When
there are heavy rains for a long period of time, the soil will crumble and
washes away. This leads to landslide on steep hillsides. (Refer appendices-12)
Then, the eroded soil is carried by the flow of the water
to the river and deposited in the bottom of river. If this continue for to
happen, the water catchment areas will deplete and causes flash floods during
rainy seasons.

In
a nutshell, deforestation disrupts the normal weather patterns, creating
hotter, drier weather and causing the change in climate. The removal of trees
reduced respiration, rainfall and the rate at which plants absorb carbon
dioxide from atmosphere during photosynthesis. This leads to an increase in the
concentration of carbon dioxide in the atmosphere. This will prevent heat from
escaping from the atmosphere. Burning of trees normally adds around 25% more
carbon dioxide to the atmosphere.