Human impact on the environment refers to the changes in ecosystems, biodiversity, and natural resources caused by human activities [1]. It includes environmental degradation, pollution, climate change, and ocean acidification.
For economic development and better living, man has sacrificed forest land for agriculture, industries, urbanization, etc. This has brought trail environmental disaster and backfired on the man himself, endangering his existence on earth.
Agriculture
The dawn of human civilization can be traced back to the discovery of agriculture almost 10,000 years ago. In the early period, man used the primitive practice of slash and born cultivation or shifting cultivation, which is still prevalent in many tribal areas, such as in North East in the hill regions.
The two modes of agriculture, traditional and modern, are described below as their impacts.
(i) Traditional Agriculture and its Impact:
It involves small plots, simple tools, natural water, organic fertilizer, and several crops. The yield is low, but it is still used by about 50% of the world’s population. The impacts of this type of agriculture are as follows:
(a) Depletion of Nutrients:
During the slash and burn of trees in forests, the organic matter in the soil is destroyed, and within a short period, the crops take up most of the nutrients. Thus the soil becomes deficient in nutrients and compels the cultivators to shift to another area.
(b) Deforestation:
Forest land is cleared by slashing and burning trees in the forest for cultivation. Frequent shifting of cultivation plots leads to deforestation i.e., loss of forest cover.
(c) Soil Erosion:
As a result of deforestation, the soil gets exposed to weathering forces i.e., rain, wind, and storms, and is subjected to erosion. The net result is the loss of top fertile soil.
(ii) Modern Agriculture and its Impact:
It is based on high input–high output technique using hybrid seeds of high-yielding variety and abundant irrigation water, fertilizers, and pesticides.
This is the basis of the “Green Revolution,” which boosted wheat production, and India became self-sufficient in food. But the fallout from Green Revolution has become evident since the 90s (1990), as shown below:
(a) Impacts from HYV (High-Yielding Varieties):
Application of seeds of HYV gave rise to mono-culture i.e., the same species (genotype)
grown over vast areas, such monoculture is vulnerable to attack by some pathogen, which
spreads like wildfire, devastating crops over large areas.
(b) Fertilizer Problems:
Chemical fertilizers supply essential micro-nutrients nitrogen, phosphorus, and potassium (NPK). Indiscriminate use of chemical fertilizers causes a micro-nutrient imbalance in the soil, ultimately leading to a loss of productivity.
(c) Nitrate Pollution:
From agricultural fields, nitrogenous fertilizers leach into the soil and finally contaminate groundwater. When the nitrate level of groundwater exceeds 25 mg/l, it can cause a serious health hazard known as “Blue Baby Syndrome,” which primarily affects infants and even leads to their death.
(d) Eutrophication:
Agricultural run-off water contains fertilizer components, particularly nitrogen, and phosphorus, which reach nearby water bodies and cause their nourishment. Excessive use of these fertilizers leads to over nourishment of the lakes/water bodies and gives rise to eutrophication.
As a result, there is excessive growth of algal species, known as an algal bloom. The water body or lake soon gets filled up with algal species, which quickly complete their life cycle and die, thus adding a lot of organic matter.
Dissolved oxygen in the lake is consumed, and fish get killed, so the lake becomes a dead pool of water devoid of plants and animals. Thus the lake ecosystem gets degraded due to eutrophication.
(e) Pesticide Side Effects:
Several thousand pesticides are used in agriculture for destroying pests and boosting crop production. In early human civilization, arsenic, sulfur, lead, and mercury were used to kill pests. Since 1940 synthetic organic pesticides have been used.
Among these, DDT (dichlorodiphenyltrichloroethane), discovered by Paul Mueller (1939), deserves special mention. From 1940 to 1950, it saved 5 million lives from malaria, typhus, etc., and protected crops from huge losses. But DDT and other pesticides show several harmful side effects on the environment.
Inducing Pest Resistance and Yielding New Pests:
In the course of time, new generations of pests develop resistance to pesticides to survive even after pesticide spray. About two dozen pest species are known to be immune to all types of pesticides.
Biological Magnification/Amplification:
Many pesticides, including DDT, are non-biodegradable and persist in the food chain. At each step of the food chain, the pesticide level gets more and more concentrated. This is the process of biological magnification or amplification.
Thus, DDT builds up from 0.04 ppm in plankton to 75 ppm in fish-eating birds. Man occupies a high trophic level in the food chain and hence gets a high dose of pesticide, which is quite harmful.
Waterlogging:
Excessive irrigation of croplands for good growth of crops leads to waterlogging. In the absence of adequate drainage, excess water is accumulated, seeping into the underlying water table.
Pore spaces in the soil get fully drenched with water, and soil air becomes deficient. The water table rises, and the roots of plants have insufficient air for respiration. There is a decline in crop yield with a decrease in soil strength.
Salinity Problem:
In addition to waterlogging, salinity also rises from excessive irrigation water. The latter contains dissolved salts that evaporate under dry conditions, leaving salts in the upper soil profile.
Saline soils are characterized by the accumulation of soluble salts, such as sodium chloride, sodium sulfate, calcium chloride, magnesium chloride, etc., in the soil profile.
Salinity causes stunted plant growth and reduces crop yield. Thousands of hectares of land in Punjab have been affected by soil salinity. The best method for removing salinity is to flush it out by applying freshwater to such soils.
Industry
Industries produce environmental hazards everywhere. They consume 37 percent of the world’s energy and emit 50 percent of the world’s CO2, 90 percent of SOx, and almost all the chemicals now threatening the O3 layer with depletion.
They produce 2100 million tonnes of solid waste annually and 350 million tonnes of hazardous waste. In developing countries, small as well as big industries discharge untreated waste. There is worldwide concern about the disposal of radioactive wastes from nuclear reactors.
Nuclear reactor accidents are expected to increase over the years. The stock of nuclear power stations is also aging. In developed countries, industries have enforced economies during the last two decades in the use of resources and energy consumption.
It is a common practice for these industries to recycle and reuse water. The average person in a developed country still consumes 15 times more energy than in a poor country. However, in developed countries, energy is being used more efficiently, and the expected rate of increase in energy
consumption is only 1.3 percent per year.
Transport
Transport is a great consumer of land and energy. The length of motorways has almost doubled in developed countries over the past two decades, reaching 1,500,00 km. in 1990.
Transport consumes 30 percent of the world’s energy (82 percent is consumed on roads), producing 60 percent of CO emissions, 42 percent of NOx, and 40 percent of hydrocarbon emissions.
But there is a hope of new cleaner transport becoming popular in future. Almost one-third of Brazil’s cars run on pure ethanol, obtained from specially grown crops, and many run on an ethanol/petrol mixture.
Natural gas is used as a fuel in several countries, including Italy, where 3 lakh cars run on compressed natural gas (CNG).
Developed countries have significantly reduced petrol consumption by 50 percent of the amount used two decades ago. Auto-emissions have also been cleaned up.
Lead-free petrol has curtailed Lead (Pb) emissions by 87 percent during 1980-1990.
Mining
Minerals find extensive use in domestic, agricultural, industrial, and commercial sectors and thus form a very important part of any nation’s economy. Minerals are broadly of two types:
(a) Non-metallic minerals e.g., graphite, diamond, quartz, feldspar etc.
(b) Metallic minerals e.g., bauxite, laterite, hematite, etc.
Since the early days of human civilization, man has used metals extensively. That is why history labeled the eras as Bronze Age and Iron Age.
Iron and Steel are the most abundantly used metals (Annual use of 750 million tonnes) followed by Manganese, Copper, Chromium, Nickel, and Aluminium.
Mining and processing of minerals involve major environmental concerns, including disturbance of land, air pollution from dust and smelter emissions, and water pollution from disrupted aquifers.
Six major mines are known to cause severe environmental problems.
(a) Jadugoda Uranium Mine, Jharkhand: Exposing local area and the population to radioactive hazards.
(b) Jharia Coal Mines, Jharkhand: Underground fire causing land subsidence and displacement of people.
(c) Sukinder Chromite Mine, Orissa: Seeping of hexavalent chromium into river posing a serious health hazard. Chromium Cr+6 (hexavalent) is highly toxic.
(d) Kudremukh Iron Ore Mine, Karnataka: Causing river pollution and threat to biodiversity.
(e) East-Coast Bauxite Mine, Orissa: Land encroachment and rehabilitation issue.
(f) North-Eastern Coal Fields, Assam: Very high sulfur contamination of groundwater.
Impacts of Mining:
Mining involves the extraction of minerals/fossil fuels from deep deposits in soil employing the techniques of sub-surface mining or surface mining.
The former method is more dangerous and expensive, including risks and accidents. The environmental damages are described as follows:
(a) Devegetation and Defacing of Landscape:
Large-scale devegetation or deforestation leads to ecological imbalances besides disfiguring the landscape. The huge debris and tailings spoil the region’s environment and make it vulnerable to soil erosion.
(b) Subsidence of Land:
Underground mining (e.g., coal) causes subsidence of the soil above, resulting in tilting of buildings, cracks in soil/road, bending of rail tracks, etc.
(c) Groundwater Contamination:
Mining disturbs the hydrological processes and also pollutes the groundwater. Sulfur impurity in many areas gets converted into sulfuric acid through microbial action, which makes the water acidic.
The acid mine drainage often contaminates the nearby streams and lakes and damages aquatic life (plants and fish).
(d) Air Pollution:
In metallurgical industries, smelters in metal extraction processes emit massive air pollutants, sulfur oxides, soot, arsenic, lead, cadmium particles, etc. These have public health hazards for local residents.
(e) Occupational Health Hazards:
Most miners suffer from respiratory and skin diseases due to constant exposure to suspended particulate matter and toxic substances. Such diseases include asthma, bronchitis, black-lung disease, asbestosis, silicosis, etc.
Sustainable Development
As per the definition of the then director of the World Health Organization (WHO), Prime Minister G.H. Bruntland (Norway), sustainable development means “meeting the needs of the present without compromising the ability of future generations to meet their needs”!
Nowadays, sustainable development is the keynote of many projects, but only a few achieve sustainable growth.
The essential components of sustainable development are:
• Population stabilization (growth below 0.5 percent)
• Integrated land-use planning
• Conservation of biodiversity
• Air and water pollution control
• Renewable energy resources
• Recycling of wastes and residues
• Environmental education and awareness at all levels.
Questions
What is the significance of sustainable development? What are its main components?
Sustainable development is a way of meeting the needs of the present without compromising the ability of future generations to meet their own needs.
It is a concept that seeks to balance economic, social, and environmental concerns to create a more sustainable and equitable world. The main components of sustainable development are:
Economic development: This involves creating economic opportunities and improving living standards while minimizing negative environmental and natural resource impacts.
Environmental protection: This involves protecting and preserving natural resources, such as forests, water, and air, for future generations. It also involves minimizing pollution and waste and promoting clean and renewable energy sources.
Social development: This involves promoting social justice and equity and ensuring that all people have access to basic human rights, such as education, healthcare, and housing. It also involves promoting cultural diversity and respect for different communities and cultures.
Good governance: This involves transparent and accountable decision-making processes that involve all stakeholders and consider the long-term impacts of actions. It also involves the effective management of natural resources and the fair distribution of benefits and costs.
Give a short account of the impacts of agriculture on the environment.
Agriculture can have both positive and negative impacts on the environment. Some of the main impacts of agriculture on the environment include:
Land use and deforestation: Agriculture often involves the conversion of natural habitats, such as forests, into agricultural land. This can lead to deforestation and the loss of biodiversity.
Soil erosion and degradation: Improper agricultural practices, such as the overuse of chemicals and monoculture, can lead to soil erosion and degradation, which can reduce the productivity of the land and harm the environment.
Water pollution: Agricultural chemicals, such as fertilizers and pesticides, can leach into water sources, leading to water pollution. This can harm aquatic life and affect the quality of drinking water.
Climate change: Agricultural practices, such as livestock farming, can contribute to greenhouse gas emissions, contributing to climate change.
Habitat destruction: Agricultural expansion can also destroy habitats, such as wetlands and grasslands, harming wildlife.
What is meant by Eutrophication?
Eutrophication is when a body of water becomes overly enriched with minerals and nutrients, often leading to the excessive growth of aquatic plants and algae.
What is meant by Waterlogging?
Waterlogging is the saturation of soil with excess water. It can cause the soil to become anaerobic, resulting in poor plant growth and other problems.
What is meant by the Salinity of soil?
The salinity of soil refers to the amount of salt in the soil. High salinity levels can lead to poor crop growth, moisture loss, and other negative effects.