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Файл:Fundamentals of Geography. Study guide
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Human impact on the biosphere
71
of artificial canals and dams, and much more. However, up to a certain time the
changes were not significant. In the last few decades, these actions in certain
areas have become critical and dangerous for the existence of man himself.
As a result of economic activity, a huge amount of chemical compounds is released into the atmosphere. This leads to an increase in the concentration of atmospheric aerosols, which causes a decrease in direct solar radiation to the
Earth's surface. As a result of the burning of all types of combustible minerals,
the amount of carbon dioxide in the atmosphere increases, which, according to
calculations, increased the average global temperature of the Earth's surface by
0.6 °C (Revvel, Revvel, 1995).
The most striking example of the impact of anthropogenic factors on the
global climate of the planet is the emergence of the problem of the "ozone hole"
over Antarctica. It is known that atmospheric ozone is formed as a result of complex photochemical reactions under the influence of ultraviolet radiation from
the Sun. Although its content is small, its significance for the biosphere is
enormous. Ozone, absorbing ultraviolet radiation, protects all life on Earth from
death.
In the early 80s, it was found that the amount of ozone in the atmosphere in
the south polar region of the Earth began to decrease. In October 1985, foreign
reports appeared that the ozone content in the atmosphere over the English Antarctic station Halley Bay has been falling catastrophically over the past 10 years,
and the concentration of ozone in the layer 15–25 km above the Japanese station
Syova in Antarctica in the spring has decreased by 2 times. This decrease in the
concentration of ozone over Antarctica has been called the "ozone hole". Various
hypotheses of the origin of this phenomenon have appeared, and above all the role
of the anthropogenic factor.
In August 1986, an expedition of the US National Science Foundation car-
ried out a complex of works at the South Pole, which made it possible to find
out the main causes contributing to the formation of the "ozone hole". It was
found that the intensity of ozone depletion was actively influenced by meteorological conditions, i.e. the amount of ozone input to Antarctic regions had
changed: there was a "shortage" of ozone during the winter period, and the most
important reason was the anthropogenic factor – the use of chlorofluorocarbons
(freons).
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72
It is known that freons are widely used in production and everyday life as refrigerants, foaming agents, solvents, as well as in aerosol packages. According to
foreign sources, freons can stay in the atmosphere for about 50–200 years (Revvel,
Revvel, 1995). Freons entering the atmosphere, under the influence of solar radiation, break up into a number of compounds, which contain chlorine oxide, which
intensively destroys ozone.
In addition, freons, like carbon dioxide, contribute to the "greenhouse effect",
thus make global climate warming problem more serious. In 1977, the use of freons in the production of aerosols was banned in the UK, which became widespread
all over the world. According to WHO, a decrease in stratospheric ozone content
by 1 % (and, accordingly, an increase in UV radiation by 2 %) leads to an increase
in number of human skin cancer by 6 %; the human immune system is significantly
weakened, the number of eye cataract diseases increases, etc.
In 1985, an international protocol was developed (the Montreal Protocol on
Substances that Deplete the Ozone Layer), the purpose of which was to counteract
the destruction of the ozone layer – the phasing out of the production and use of
groups of ozone-depleting substances freons. On condition of 2010, 196 UN member States ratified its original version. In the USA and Russia, active physicochemical methods (laser, electromagnetic) have been developed that accelerate the formation of ozone in the stratosphere, which will preserve the ozone shield, and
hence modern terrestrial civilization.
A man has always been pleased with blessed raindrops, but in some areas of
the globe rains have turned into a serious danger. A complex and difficult problem of acid rain appeared, that was difficult to be solved. Technogenic sulfur
emissions into the Earth's atmosphere reaches 75–100 million tons per year.
about 60 % of these emissions come from the burning of coal, another 30 % is
from petroleum products, the remaining 10 % are accounted for by chemical industry and metallurgy enterprises. The problem of acid rain at the international
level was first discussed by Sweden at the UN Environment Conference, held in
Stockholm in 1972. Since then, it has become one of the main environmental
problems of mankind.
Acid rains, i.e. sulfuric and nitric acids dissolved in atmospheric precipitation,
have a detrimental effect on living organisms of reservoirs, damage forest vegetation and agricultural crops, and finally, all these substances pose a certain danger
to human health (Fig. 15).
Human impact on the biosphere
73
Fig. 15. Acid rain and its consequences (according to Vronsky, 2006)
Hundreds of lakes in many areas of Scandinavia, southeastern Canada, the
USA, and Scotland have turned into acidic reservoirs. The more acidity of the
water is, the faster aluminum content increases, which leads to numerous fish kill
in Swedish lakes. In addition, an increase in the concentration of aluminum in
water leads to a reduction in primary production, on which the life of all inhabitants of freshwater reservoirs depends. The increase in the acidity of the waters led
to the fact that in 1750 fish completely disappeared out of 5000 lakes in Southern
Norway, fishing industry in 2500 freshwater lake areas was seriously affected in
Sweden.
Acid rain has also a negative effect on soils and vegetation. An increase in the
aluminum content in soils leads to a decrease in plant viability, stimulates the processes of rotting, and reduces the productivity of forest ecosystems. Acid rains
increase the leaching of mineral nutrition elements from leaves, they are especially
toxic to conifers (pine) and increase the removal of minerals from the soil.
SO2
NOx
Acid rain
Negative consequences:
Visibility reduced
Acidification of freshwater reservoirs
Acidification of soils and reduction of fertility
Damage and death of forest formations
Extermination of some animal species
Harm to human health
Acceleration of corrosion of bridges, dams, metal structures of buildings, etc.
Damage to monuments of world architecture
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Excessive acidity accelerates corrosion of metal structures of buildings,
bridges, dams, power lines, etc. Under the influence of acid rains, architectural
monuments are destroyed, especially those which are made of carbonate rocks.
So, the famous Parthenon in Athens, Trajan's marble column in Rome, sculptural
groups in Krakow and many others are gradually destroyed by acid rains. A number of countries take various measures by putting lime fertilizers into lakes and
rivers, which somewhat reduces the damage caused by acid rain.
Impact on the hydrosphere and water balance. The fresh water resources
of Earth are formed in the process of the global water cycle, which is a desalination of water and contributes to their continuous renewal. However, the total
consumption of river waters increases from year to year in all regions of the
world. Since the beginning of this century, the consumption of fresh water has
increased by more than 6 times, and in the next 20–30 years it will increase by
at least 1.5 times.
Plowing of virgin lands and their agricultural development, agrotechnical and
forest reclamation measures, use of water for irrigation, irrigation of arid territories, creation of reservoirs, urban development, pollution of fresh water by industrial and domestic effluents affect the change in the natural regime of land reservoirs and the water balance of the planet. All this creates a complex problem of
water deficiency in some areas of the globe and forces people to develop effective
measures to optimize water consumption.
Anthropogenic transformations of waters have already spread globally. When
considering the water cycle, we have already briefly mentioned the economic unit
and the increase in water consumption in the world.
A man transforms the waters of the hydrosphere by constructing hydraulic
structures, in particular reservoirs. Many ancient civilizations developed in arid
regions where irrigation was a vital necessity (Revvel, Revvel, 1995). The first
reservoirs were created in ancient Egypt more than 3000 years BC, which allowed the Egyptians to develop the formerly dry lands of the Nile Valley. Sometime later, reservoirs were built in Mesopotamia, the Middle East, China, India,
Japan and other countries for the purpose of irrigation and flood control. In
Russia, under the reign of Pe ter I, the connection the rivers of Moscow and
Volga, Volga and Don was planned. The first reservoir in Russia was created
in 1703–1709 by M. I. Serdyukov on the Vyshnevolotsk system, which connected the Volga with the Baltic Sea.
Human impact on the biosphere
75
Modern reservoirs are hydraulic structures for the retention and accumulation
of water for the purpose of its consumption for economic needs (electricity generation, irrigation of land, drinking water supply, navigation, fishing, recreational
purposes, etc.). In the twentieth century, the building of reservoirs reached a huge
scale in the world, which eventually began to have a significant impact on the
hydrosphere and the water balance of our planet.
According to Avakyan (2002), at present there are more than 60 thousand reservoirs on the globe, the water-surface area of which is about 100 thousand km2,
and the volume of water has exceeded 6,600 km3. However, more than 90 % of
the total volume of water falls on large reservoirs (with a volume of more than
100 million m3). There are more than 3000 of them in the world, of which Asia
accounts for 937, North America – 931, Europe – 603, Africa – 185, etc. The
largest reservoirs in the world (in terms of water volume, in km3) are: Victoria
(Uganda) – 204.8; Bratskoe (Russia) – 169.3; Caribbean (Zambia) – 160.3, etc.
237 large reservoirs were built on the territory of the former USSR, including
the largest valley reservoir (in terms of water volume) – Bratskoye, and the second
in the world in terms of mirror area – Kuibyshevskoye (5900 km2). In Russia, the
major reservoirs are: Zeyskoye, Ust-Ilimskoye, Boguchanskoye, Krasnoyarsk, etc.
However, large reservoirs have also serious negative impacts on the environment: they change the groundwater regime in the coastal area, affect soils and plant
communities, their water areas occupy large territories of fertile land, etc. These
problems have become particularly acute in recent years and have turned into reasonable concerns to society. We need to consider many fixed notions again and
pay much attention to the environmental issues of the operation of reservoirs in
order to reduce their impact on the environment.
The effectiveness of water resources protection is closely related to the point
of how much they are saved in all sectors of the economic link of the water cycle.
This is especially true for irrigated agriculture, which nowadays requires more
than 70 % of the world's irretrievable water consumption. Therefore, in many
countries, they try to search for the latest advanced irrigation technologies, so drip
irrigation is 3–4-times more beneficial than modern irrigation methods regarding
water savings. To solve the problems of rational water use, it is necessary to join
the efforts of scientists from different countries together.
Impact on soils and vegetation cover. As a result of human influence on the
living matter of the biosphere, the natural life of the earth's surface – its soil and
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76
vegetation cover – changes significantly. On our planet, only 10 % of the land is
arable and is used in agriculture. 40 % of agriculture in the world is concentrated
on four types of soils: chernozems, dark prairie soils, gray forest and brown forest
soils (Maksakovsky, 2006). The best soils are plowed, and in the future a man will
have to develop less favorable land resources, using artificial irrigation, land reclamation, soil salinization, etc. As a result of the impact of anthropogenic factors
(erosion, irrigation, secondary salinization, etc.), there is a sharp decrease in soil
fertility (Fig. 16).
Fig. 16. Factors of degradation and reduction of soil fertility
(by Gorshkov, 1987)
Soil degradation in the world is global, almost 2 billion ha of soils are exposed to it., 55,6 % of which is due to water erosion, 28 % is because of wind
erosion, etc.
The land resources of the Russian Federation include 1709.8 million hectares.
They are classified into: agricultural lands (662 million hectares), forest lands
(828 million hectares), etc. In Russia, there are 1.3 hectares of farmland per 1 person (0.8 hectares of them are arable land), on average this value is 0.14 hectares
of arable land worldwide (in the USA – 0.6, China – 0.09 hectares). In Russia, the
soil condition is very unsatisfactory: out of 186 million hectares, 32 % are subject
FACTORS OF SOIL DEGRADATION
The open-pit mining
Irrigation and drainage
Secondary salinization
Overgrazing
Acid rain
Soil erosion
Toxicant contamination
Application of pesticides
Incorrect agricultural
technology
Urbanization
Human impact on the biosphere
77
to erosion, 21,5 % to secondary salinization, 27 % to progressive desertification,
etc. The intensification of soil degradation processes leads to a decrease their fertility and the productivity of farmland (Gorshkov, 1987: Maksakovsky, 2006).
The widespread use of pesticides to control pests, weeds and plant diseases has
a harmful effect on soils. Excessive use of pesticides in agriculture opens the door
for their accumulation in soils, as well as in nearby reservoirs and vegetation.
For the last few years, the problem of soil salinization in arid areas has become
more acute. Around the world, 40 % of irrigated lands are subject to salinization.
Even with weak soil salinization, crop yields are sharply reduced: cotton – by
50–60 %, wheat – by 40–60 %, corn – by 40–50 %. the main cause of secondary
salinization of soils is the rise of mineralized groundwater, which arose as a result
of breaking the water balance of the territory by filtration waters of irrigation systems and irrigated lands.
It should be noted that in the world there is a tendency to reduce the area of
productive land due to intensive human activity. Therefore, the problem of recultivation of man-made landscapes has arisen. The ultimate goal of these works is to
create productive biocenosis on the surface of dumps, mainly for agricultural and
forestry purposes.
Forest plantations on rock dumps have an important reclamative, soil protection and rehabilitation role. Along with these types of recultivation, water reclamation activities are sometimes done at the site of old quarries, which have the
following tasks: the creation of reserves of industrial water or drinking water, recreational centers and zones. Artificial lakes in former mining pits in combination
with forest plantations on dumps can serve as recreation areas. On the dumps of
rocks in Kuzbass, in the Urals, in the Donbass, full forests (from pine, birch, alder,
sea buckthorn, etc.) have been planted. In recent years, the area of reclaimed land
in Russia annually is 58–72 thousand hectares.
Similar recultivation of damaged lands is done in other countries (such as
USA, England, Germany, the Netherlands). Since the world is experiencing a further boost in the extraction of many minerals using the open-pit mining, the importance of reclamation research and activities should become increasingly important, being an integral part of the protection and reproduction of land resources.
The role of plants in the biosphere is huge due to their ability to carry out
photosynthesis. Vegetation influences all components of the natural complex of
the biosphere – the atmosphere, the hydrosphere, the soil, the animal world. The
Topic 9
78
role of plants in the life of human society is immense. They create the necessary
environment for existence and supply it with various substances. Forests cover
about 1/3 of the surface of all the continents. Forests are one of the types of renewable resources of the biosphere. Although forests are the most productive biological formations on the globe, but due to intensive deforestation by humans, in
some cases they don’t have the ability to restore. Every year, the world's demand
for wood increases, and the size of the forested area reduces. Tropical rainforests
are destroyed especially quickly, the reason is the lands occupied by them is used
in agriculture, as well as roads and settlements are built. (Table 8).
Table 8
Areas and rates of rainforest reduction in the largest land areas
(according to S. P. Gorshkov, 2007)
Place
Area of forests
(mln. hectare)
Deforestation rate
(mln. hectare/year)
%
Central America
60
1,0
1,7
South America
526
8,9
1,7
Western Africa
100
0,9
0,9
Eastern Africa
88
0,8
0,9
Western Asia
31
1,1
3,5
South-Eastern Asia
330
7,1
2,1
It has been found out that deforestation leads to a change in the albedo of the
earth's surface and disrupts the carbon balance in the atmosphere, as well as intensifies erosion processes. The destruction of forests in India has led to an increase
in the modern denudation of land by almost 5 times, which contributes to the siltation of reservoirs, etc.
Within the framework of the UNESCO program "Man and the Biosphere" in
Venezuela in the Amazon basin, scientists from a number of countries conducted
a unique experiment to study the ecosystem of tropical rainforests. With the help
of "labeled atoms" of nutrients (calcium, phosphorus), it was found that over 99
% of them were absorbed by the root layer. This shows that almost all the nutrients
released as a result of the decomposition of organic matter are absorbed directly
by the roots of plants, bypassing the mineral part of the soil. The root layer (up to
30 cm thick) in humid tropical forests prevents the loss of nutrients, and doesn’t
Human impact on the biosphere
79
let them leave their systems. These studies have revealed the greatest weakness of
the ecosystem of tropical forests – when they are destroyed, despite the resilience
and abundance of biomass, the productivity of these systems drastically drops.
Humid tropical forests have proved to be less resistant to anthropogenic impact
compared to forests of temperate latitudes, and some researchers even classify
them as nonrenewable resources.
A man realized that his existence on the planet depends on the life of forest
formations. Therefore, in recent years, the inventory of tropical forests, as well as
artificial afforestation has been made in many countries of the world. For example,
in the USA, the size of area of forests decreases by an average of 2.8 million hectares per year, but an area of 650–750 thousand hectares is annually planted. In
recent decades, reforestation and the organization of highly productive forest plantations have become widespread in European countries.
However, many plant species have become rare or endangered due to direct or
indirect human influence. It has been established that at least 25–30 thousand species of vascular plants, or 8–10 % of the total number of them on Earth, are under
threat of extinction on our planet. The second edition of the Red Book of the USSR
(1984) included about 603 species of rare higher plants. These include: water walnut, ironwood, silk acacia, oak (Imeretian, Pontic, chestnut-leaved), Hyrkan boxwood, oriental plane tree, holly, pistachio, berry yew, pine (Pitsunda, Eldar, chalk,
grave), Semenov fir tree, wingnut, Asiatic poplar, etc. Rare and endangered plant
species are protected mainly in various types of protected areas (nature reserves,
nature reserves, etc.).
Impact on the animal world. Together with plants, animals play an exceptional role in the migration of chemical elements, which underlies the relationships
existing in nature. The role of animals in human life is also significant. Many of
them serve as an important source of nutrition and technical raw materials (farm
animals, fish, fur-bearing animals, game, etc.). The fauna of wild animals is a natural source for the domestication of valuable fur-bearing animals (sable, mink,
arctic fox, fox, etc.).
However, human economic activity has greatly influenced the animal world of
our planet. According to the International Union for Conservation of Nature,
94 species of birds and 63 species of mammals have become extinct on Earth since
1600. The fauna of oceanic islands was particularly affected. For example, 26 bird
species, or 60 % of the entire fauna, have become extinct on the Hawaiian Islands.
Topic 9
80
Under the influence of anthropogenic factors, 86 % of local bird species have become extinct on the Mascarene Islands (the Indian Ocean), which is the highest
percentage of extinct species in the world. Human impact on animals is seen both
in direct persecution and violation of the population structure, and when they
change their habitats. Recently, a powerful factor of environmental pollution, especially pesticides, has been added to the list of general changes in living conditions.
All of the above mentioned factors have become reasons of extinction of many
animals: tarpan, tur, zebra-quaggy, marsupial wolf, sea mink, European ibis, blue
horse antelope, sea (Steller's) cow, etc. The latter, a large representative of the
order of sirens was 7–8 m long and weighed 4 tons. For the first time this animal
was described by naturalist G. Steller in 1741, a doctor of the Russian expedition
of Vitus Bering. The delicious meat of Steller's cows, and their credulity caused
death. Intensive hunting led to the fact that by 1768, i.e. 27 years after their discovery, there were no sea cows. The same situation was with many birds (the flightless dodo pigeon, the wingless loon, the spectacled cormorant, the Carolina parrot,
etc.). as a result of human activity on the continents, the number of endangered and
rare animal species has increased. So, in North America, bison, the white American
crane, the California condor were on the verge of extinction; in South America, the
vicuna, large cats. The number of animals such as rhinoceros, lion, tiger, cheetah,
lancer, Przewalski's horse and many others has drastically decreased in Asia.
In our country, by the beginning of the twentieth century, many species of
valuable animals had become rare, and some were on the verge of extinction.
Hunting for them was completely prohibited, and reserves were established to conserve and reproduce the most valuable species (buffalo, river beaver, sable, muskrat, kulan). The fate of buffalos is especially interesting. The last buffalo was
killed in the Belovezhskaya Pushcha in 1919, and in the Caucasus – in 1927, only
48 buffalos were preserved in zoos, the buffalos were threatened with extinction
from the planet. Colossal work began to restore the number of buffalos, some
individuals w ere used, which were kept in zoos. In total, there are more than
2000 buffalos in the world, of which 80 % are found in Central Europe. The
number of Amur tigers has increased (at the beginning of the XXI-st century it
exceeded 400 heads), polar bears (about 25,000 individuals in the Arctic alone),
sea otters, or sea otters. When sea otter fishing was banned, its number has now
increased to 5,000 individuals in the Kuril Islands and up to 3,000 in Kamchatka.
But by the end of the XIX-th century. the sea otter was almost completely killed,
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