Mineral Resources
Mineral Deposits
Metallic resources are those minerals that contain metals in their chemical composition (a product obtained when the mineral was melted). These usually have bright and metallic luster. Examples include iron ore, chromite and bauxite.
Non-metallic resources such as sand, gravel, gypsum, halite, talc, are those resources that do not yield new products when melted. These do not have metallic luster.
There are many geologic processes involved in the rock cycle that plays a major role in the accumulation and concentration of valuable elements / minerals.
1. Magmatic Ore Deposits
These deposits are substances concentrated within an igneous body through magmatic processes such as crystal fractionation and crystal settling. These magmatic processes concentrate the ore minerals having the valuable substances that were widely dispersed and in low concentrations within the magma.
Crystal settling . The early crystallization and settling of heavier minerals at the lower portion of the magma chamber as magma cools down.
Examples are Chromite (FeCr2O4), Magnetite (Fe3O4) and Platinum (Pt).
Fractional crystallization . The residual melt from separated component favors the formation of pegmatites which may be enriched in Lithium, Gold, Boron or large crystals of quartz, feldspars and muscovite.
2. Hydrothermal Ore Deposits
These are substances by concentrated through hot aqueous (water-rich) fluids flowing through fractures and pore spaces in rocks. These hydrothermal solutions can dissolve valuable substances (at low concentrations) from rocks. When the metal enriched hot waters move into cooler areas the dissolved substances precipitate into solid forms.
• Vein type deposits (in fault or fissure openings or in shear zones ) has most productive deposits of gold(Au), silver(Ag), copper(Cu), lead(pb) , zinc(Zn), and mercury(Hg).
• Disseminated deposits (large volumes of rocks) for porphyry copper deposits
• Massive sulfide mineral deposit (at oceanic spreading centers or ridges) such as sphalerite (ZnS) and chalcopyrite (CuFeS2)
.• Strata bound ore deposits (in lake or oceanic sediment) forms minerals such as galena (PbS), sphalerite (ZnS) and chalcopyrite (CuFeS2).
3. Sedimentary Ore Deposits
A type of deposit of valuable substances concentrated through chemical precipitation from lakes or seawater.
The most commom are evaporite deposits (in closed marine environment) that precipitate halite (NaCl), gypsum (CaSO4∙2H20), borax (used in soap), sylvite (KCl), hematite and magnetite.
4. Placer Ore Deposits
These are deposits of valuable substances concentrated through gravity separation during sedimentary processes. In these process, the heavy minerals are left and concentrated by water currents and the less-dense particles remain suspended and are carried further downstream.
Common placer ore deposits are gold, platinum, diamonds and tin.
5. Residual Ore Deposits
An accumulation of valuable substances through chemical weathering processes wherein the volume of the original rock is greatly reduced by leaching.
Common deposits are bauxites (the principal ore of aluminum ) and
nickeliferous laterites or nickel laterites (mixture of the insoluble nickel, magnesium and iron oxide ).
Lesson 4.2 – Mineral Exploration
Mineral exploration follows the well-defined stages. The steps below are for general exploration projects wherein the activities may be different based on the type of mineral being explored.
1. Project Design
This is the initial stage in formulating a project. This involves review of all available data (geologic reports, mining history, maps, etc.), government requirements in acquiring the project, review of social, environmental, political and economic acceptability of the project, and budget and organization proposals.
2. Field Exploration
This stage involves physical activities in the selected project area. This can be subdivided into three phases:
a. Regional Reconnaissance
The main objective is to identify targets or interesting mineralized zones covering a relatively large area (regional). In general, the activities involve regional surface investigation and interpretation.
b. Detailed Exploration
This involves more detailed surface and subsurface activities with the objective of finding and delineating targets or mineralized zones.
c. Prospect Evaluation
The main objective is to assess market profitability by
(1) extensive resource, geotechnical and engineering drilling
(2) metallurgical testing and
(3) environmental and societal cost assessment.
3. Pre-production Feasibility Study
The feasibility study determines and validates the accuracy of all data and information collected from the different stages. The purpose is for independent assessors to satisfy interested investors to raise funds and bring the project into production.
Mining Methods
1. Surface Mining
This mining is used to extract ore minerals that are close to Earth’s surface. The different types include open pit mining, quarrying, placer mining and strip mining.
Open pit mining creates big hole in the ground from which the ore is mined.
Quarry is a type of open pit mine usually associated with the mining of non-metallic resources such as limestone, sand and gravel.
Placer mining uses water to excavate, transport, concentrate, and recover heavy minerals from alluvial sediments or placer deposits.
In Strip mining method, ore is removed or extracted in strips. This involves removing the top layer of soil instead of digging deep holes.
2. Underground Mining
This method of mining is used to extract ore minerals that is deep under the Earth’s surface.
The Milling Process
The materials extracted or “mined" are rocks composed of both ore and waste material. Waste materials are part of the rock which contain very little or no element or mineral of economic value. The rocks that were extracted will further undergo processes of mineral (e.g. metal) separation and recovery through some processes usually done in a mill.
Initial Stage
The initial stage involves crushing and screening for controlled size reduction followed by grinding where the rocks are pulverized.
1. Heavy media separation
The crushed rocks are submerged in liquid where the heavier/denser minerals sink thus are separated from the lighter minerals. This is commonly used to separate chalcopyrite from quartz before the refining processes of extracting copper.
2. Magnetic separation
If the metal or mineral is magnetic, the crushed ore is separated from the waste materials using a powerful magnet.
3. Flotation
The powdered ore is placed into an agitated and frothy slurry where some minerals and metals based on physical and chemical properties may either sink to the bottom or may stick to the bubbles and rise to the top thus separating the minerals and metals from the waste.
4. Cyanide heap leaching
This method used for low-grade gold ore where the crushed rock is placed on a “leach pile” where cyanide solution is sprayed or dripped on top of the pile.
As the leach solution percolates down through the rocks, the gold is dissolved into the solution. The solution is processed further to extract the gold.
The waste material is either used as a backfill in the mine or sent to a tailings pond, while the metals are sent for further processing.
Environmental Impacts
There are several possible environmental impacts of irresponsible mining. Improper mining can cause flooding, erosion, subsidence, water and air pollution, damage to wildlife and habitat.
These are some of the measures that may prevent or mitigate the harmful effects of irresponsible mining:
1.) Topsoil replacement using uncontaminated soil
2.) Reintroduction of flora and fauna
3.) Neutralizing acidic waters
4.) Backfilling and sealing of abandoned underground mines
5.) Stabilizing the slope of impacted area to reduce erosion
6.) Promote environmental awareness and protection in relation to mining.
Energy Resources
Energy
Energy is a very important resource for human consumption. It has many uses in the field of Agriculture, Transportation, Residential, Commercial and Industrial purposes.
There are also various energy sources which can be classified into two broad categories:
Non-Renewable Sources
1. Coal
2. Oil
3. Natural Gas
4. Nuclear
Renewable Energy Sources
1. Solar
2. Wind
3. Hydroelectric
4. Biomass
5. Geothermal
Types of Energy Resources
A.) Fossil Fuels
Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of dead organisms that have been buried for thousands or millions of years and mostly contain high amounts of carbon. These energy resource include coal, natural gas, petroleum and other fuel derivatives such as kerosene and propane.
1. Coal
Coal is a very combustible black or brownish-black sedimentary rock formed in layers of rock strata in layers or veins referred to as coal beds or coal seams.
It is composed mainly of carbon and with smaller amounts of other elements such as hydrogen, oxygen, sulfur, and nitrogen.
The Different Types of Coal
Anthracite contains 86 to 98% pure carbon with 8 to 3% volatile matter. It is widely used as fuel heat homes.
Bituminous coal has 70 to 86% carbon with 46 to 31% volatile matter. It is used to make coke, used in metallurgy.
Sub-bituminous coal contains 70 to 76% carbon and with 53 to 42% volatile matter. It is primarily burned in industrial boilers.
Lignite has 65 to 70% carbon with 63 to 53% volatile matter. It is considered a low-grade fuel due to its high moisture content and it is mainly used in industrial boilers.
Peat is formed from partially decomposed vegetation. It is considered a poor fuel due to the low carbon content of less than 60% and it is composed entirely of volatile matter. It was used for cooking, domestic heat and few industries.
2. Petroleum
Petroleum is a naturally occurring fossil fuel formed by the decomposition of organic matter beneath the Earth's surface over millions of years . It is a yellowish-black liquid that may be refined into various types of fuels.
The refining of petroleum is carried out in an industrial process plant wherein the crude oil or petroleum is refined or transformed into more useful products such as liquefied petroleum gas, heating oil, gasoline, petroleum naphtha, kerosene, jet fuel, diesel fuel, fuel oils, and asphalt (bitumen).
3. Natural gas
Natural Gas is a fossil fuel energy source that was formed deep beneath the earth's surface and often with or near petroleum deposits.
Natural gas is a mixture of several hydrocarbons and consists mainly of methane. It also has lesser contents in varying amounts of butane, propane, ethane, and nitrogen.
Fossil Fuel Power Generation
Steam turbines may be used to extract thermal energy from the fuel. The steam is converted to kinetic/mechanical energy. Then a rotary generator is used to further convert it to electrical energy.
B. ) Geothermal Energy
Geothermal energy is a clean and sustainable form of energy generated from the thermal energy contained in the earth. This renewable energy source can be used directly to supply heat or may be converted to mechanical or electrical energy.
C. Hydroelectric Energy
Hydroelectric energy is a form of renewable energy resource that harnesses water stored in dams, water flowing in rivers and lakes, as well as waves, tides and currents to create electricity.
Hydropower plants are the world’s leading renewable energy source, producing 83% of renewable power. Inside hydropower plants, rotating blades spin a generator that converts the mechanical energy of the spinning turbine into electrical energy.
Water Resources
Water
Water is a simple compound that is very important to life and has remarkable and useful properties. Many scientists believe that, the presence of water made life possible to exist on Earth.
Distribution of Water on Earth
Water is the considered as the most abundant substance on the surface of the Earth and nearly all ( at 97.5% ) of the Earth's water can be found in the oceans. This leaves only a small portion ( at 2.5% ) is freshwater.
Most of the freshwater locked as ice in the wide glaciers of Greenland ( 68.7% ), a small portion at permafrost (0.8%), and 30.1% as groundwater. This means, there is only 0.4% of freshwater available for humans use.
The rest of the freashwater can be found in lakes (67.4%), rivers and streams (1.6%), wetlands (8.5%) and in the atmosphere as water vapor (9.5%). Others are present in plants and animals (0.8%), and in soil moisture (12.2%).
Our knowledge of how water cycles through the environment helps us in determining the amount of water available in different parts of the world. This is referred to as the Earth’s water cycle ( or Hydrologic Cycle ). It is the global mechanism by which water moves from the air to the Earth and eventually back to the atmosphere.
Movement of Water through the Cycle
Approximately 40% of precipitation comes from previously evaporated water from the oceans while the rest from different parts of the land. Around the world, the amount of this precipitation may vary greatly. In desert climates, it may only be less than 100 mm a year, but in tropical settings precipitation rises to over 3,400 mm a year.
In temperate climates, about one-third of precipitation returns to the atmosphere through evaporation, the other third filters into the ground and adds to the groundwater and the rest flows into water bodies.
In drier climates, there is a higher the proportion of precipitation that returns to the atmosphere and lower proportion replenish the groundwater.
Earth Resources : Mineral Resources , Water Resources & Energy Resources
ECOSYSTEM : INTERACTION AND INTERDEPENDENCE
Ecology is the branch of science that deals with the relationship and interactions between organisms and their environment, including other organisms. Ecology includes not only how living things interact with each other, but how they interact with their physical environment: things such as climate, water, and soil.
Biodiversity is the variety of all life forms on earth - the different plants, animals and micro-organisms and the ecosystems of which they are a part.
Ecosystem
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces.
There are two primary types of ecosystems:
• Natural ecosystems: Natural ecosystems may be terrestrial ( meaning desert, forest , or meadow) or aquatic, ( pond ,river, or lake). A natural ecosystem is a biological environment that is found in nature (e.g. a forest) rather than created or altered by man.
• Artificial ecosystems: Humans have modified some ecosystems for their own benefit. These are artificial ecosystems. They can be terrestrial (crop fields and gardens) or aquatic (aquariums, dams, and manmade ponds).
There are two main components that exist in an ecosystem: the abiotic and biotic components. The abiotic components of any ecosystem are the properties of the environment; the biotic components are the life forms that occupy a given ecosystem.
Abiotic Components
Abiotic components of an ecosystem consist of the nonorganic aspects of the environment that determine what life forms can thrive. Examples of abiotic components are temperature, average humidity, topography and natural disturbances. Temperature varies by latitude; locations near the equator are warmer than are locations near the poles or the temperate zones. Humidity influences the amount of water and moisture in the air and soil, which, in turn, affect rainfall. Topography is the layout of the land in terms of elevation. Natural disturbances include tsunamis, lightning storms, hurricanes and forest fires.
Biotic Components
The biotic components of an ecosystem are the life forms that inhabit it. The life forms of an ecosystem aid in the transfer and cycle of energy. They are grouped in terms of the means they use to get energy. Producers such as plants produce their own energy without consuming other life forms; plants gain their energy from conducting photosynthesis via sunlight. Consumers exist on the next level of the food chain. There are three main types of consumers: herbivores, carnivores and omnivores. Herbivores feed on plants, carnivores get their food by eating other carnivores or herbivores, and omnivores can digest both plant and animal tissue. Decomposers , like fungi and bacteria ,are organisms that break down dead or decaying organisms, and in doing so, they carry out the natural process of decomposition. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development.
Ecosystems are controlled both by external and internal factors :
External factors such as climate, the parent material that forms the soil, and topography control the overall structure of an ecosystem and the way things work within it, but are not themselves influenced by the ecosystem. Other external factors include time and potential biota. Ecosystems are dynamic entities—invariably, they are subject to periodic disturbances and are in the process of recovering from some past disturbance . Ecosystems in similar environments that are located in different parts of the world can have very different characteristics simply because they contain different species. The introduction of non-native species can cause substantial shifts in ecosystem function.
Internal factors not only control ecosystem processes but are also controlled by them and are often subject to feedback loops. While the resource inputs are generally controlled by external processes like climate and parent material, the availability of these resources within the ecosystem is controlled by internal factors like decomposition, root competition or shading. Other internal factors include disturbance, succession and the types of species present. Although humans exist and operate within ecosystems, their cumulative effects are large enough to influence external factors like climate.
Processes of Ecosystems
The figure on the side, with the plants, zebra, lion, and so forth, illustrates the two main ideas about how ecosystems function: ecosystems have energy flows and ecosystems cycle materials. These two processes are linked, but they are not quite the same.
Energy that enters the biological system as light energy, or photons, is transformed into chemical energy in organic molecules by cellular processes including photosynthesis and respiration, and ultimately is converted to heat energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost it cannot be re-cycled.
Without the continued input of solar energy, biological systems would quickly shut down. Thus the earth is an open system with respect to energy. Elements such as carbon , nitrogen, or phosphorus enter living organisms in a variety of ways. Plants obtain elements from the surrounding atmosphere, water, or soils. Animals may also obtain elements directly from the physical environment, but usually they obtain these mainly as a consequence of consuming other organisms. These materials are transformed biochemically within the bodies of organisms, but sooner or later, due to excretion or decomposition, they are returned to an inorganic state.
Often bacteria complete this process ,through the process called decomposition or mineralization. During decomposition these materials are not destroyed or lost, so the earth is a closed system with respect to elements (with the exception of a meteorite entering the system now and then). The elements are cycled endlessly between their biotic and abiotic states within ecosystems. Those elements whose supply tends to limit biological
activity are called nutrients.
Interaction
Biotic components and abiotic components of an eco-system interact with and affect one another. If the temperature of an area decreases, the life existing there must adapt to it. Global warming, or the worldwide increase in temperature due to the greenhouse effect, will speed up the metabolism rates of most organisms. Metabolic rate increases with temperature because the nutrient molecules in the body are more likely to contact and react with one another when excited by heat. Accordingly, tropical ectothermic - cold-blooded-organisms could experience increased metabolic rates from an increase of as little as 5 oC because their internal temperature is almost entirely dependent on external temperature. To adapt to these circumstances, cold-blooded life forms could reside in the shade and not actively search for food during daylight hours when the sun is at its brightest.
Different Types of Ecosystems
There are essentially two kinds of ecosystems; Aquatic and Terrestrial. Any other sub-ecosystem falls under one of these two headings.
Terrestrial Ecosystems
Terrestrial ecosystems can be found anywhere apart from heavily saturated places. They are broadly classed into:
The Forest Ecosystems
They are the ecosystems in which an abundance of flora, or plants, is seen so they have a big number of organisms which live in relatively small space. Therefore, in forest ecosystems the density of living organisms is quite high. A small change in this ecosystem could affect the whole balance, effectively bringing down the whole ecosystem. They are further divided into:
• Tropical evergreen forest: These are tropical forests that receive a mean rainfall of 80 for every 400 inches annually. The forests are characterized by dense vegetation which comprises tall trees at different heights. Each level is shelter to different types of animals.
• Tropical deciduous forest: There, shrubs and dense bushes rule along with a broad selection of trees. The type of forest is found in quite a few parts of the world while a large variety of fauna and flora are found there.
• Temperate evergreen forest: Those have quite a few number of trees as mosses and ferns make up for them. Trees have developed spiked leaves in order to minimize transpiration.
• Temperate deciduous forest: The forest is located in the moist temperate places that have sufficient rainfall. Summers and winters are clearly defined and the trees shed the leaves during the winter months.
• Taiga: Situated just before the arctic regions, the taiga is defined by evergreen conifers. As the temperature is below zero for almost half a year, the remainder of the months, it buzzes with migratory birds and insects.
The Desert Ecosystems
Desert ecosystems are located in regions that receive an annual rainfall less than 25. They occupy about 17 percent of all the land on our planet. Due to the extremely high temperature, low water availability and intense sunlight, fauna and flora are scarce and poorly developed. The vegetation is mainly shrubs, bushes, few grasses and rare trees. The stems and leaves of the plants are modified in order to conserve water as much as possible. The best known desert ones are the succulents such as the spiny leaved cacti. The animal organisms include insects, birds, camels, reptiles all of which
are adapted to the desert conditions.
The Grassland Ecosystem
Grasslands are located in both the tropical and temperate regions of the world though the ecosystems vary slightly. The area mainly comprises grasses with a little number of trees and shrubs. The main vegetation includes grasses, plants and legumes that belong to the composite family. A lot of grazing animals, insectivores and herbivores inhabit the grasslands. The two main kinds of grasslands ecosystems are:
1. Savanna: The tropical grasslands are dry seasonally and have few individual trees. They support a large number of predators and grazers.
2. Prairies: It is temperate grassland, completely devoid of large shrubs and trees. Prairies could be categorized as mixed grass, tall grass and short grass prairies.
The Mountain Ecosystem
Mountain land provides a scattered and diverse array of habitats where a large number of animals and plants can be found . At the higher altitudes, the harsh environmental conditions normally prevail, and only the treeless alpine vegetation can survive. The animals that live there have thick fur coats for prevention from cold and hibernation in the winter months. Lower slopes are commonly covered with coniferous forests.
Aquatic Ecosystems
The aquatic ecosystem is the ecosystem found in a body of water. It encompasses aquatic flora, fauna and water properties, as well. There are two main
types of aquatic ecosystem- Marine and Freshwater.
The Marine Ecosystem
Marine ecosystems are the biggest ecosystems, which cover around 71% of Earth's surface and contain 97% of out planet's water. Water in Marine ecosystems features in high amounts minerals and salts dissolved in them. The different divisions of the marine ecosystem are:
• Oceanic: A relatively shallow part of oceans which lies on the continental shelf.
• Profundal: deep or bottom water.
• Benthic Bottom substrates.
• Inter-tidal: The place between low and high tides.
• Estuaries
• Coral reefs
• Salt marshes
• Hydrothermal vents where chemosynthetic bacteria make up the food base.
Many kinds of organisms live in marine ecosystems: the brown algae, corals, cephalopods, echinoderms, dinoflagellates and sharks.
The Freshwater Ecosystem
Contrary to the Marine ecosystems, the freshwater ecosystem covers only 0.8% of Earth's surface and contains 0.009% of the total water. Three basic kinds of freshwater ecosystems exist:
• Lentic: Slow-moving or till water like pools, lakes or ponds.
• Lotic: Fast-moving water such as streams and rivers.
• Wetlands: Places in which the soil is inundated or saturated for some lengthy period of time.
The ecosystems are habitats to reptiles, amphibians and around 41% of the world’s fish species. The faster moving turbulent waters typically contain a greater concentrations of dissolved oxygen, supporting greater biodiversity than slow moving waters in pools.
BIOTIC POTENTIAL AND ENVIRONMENTAL RESISTANCE
Population
It is a group of organisms of the same species living in an area at the same time.
Birth rate is the ratio of total live births to total population in a specified community or area over a specified period of time. The birthrate is often expressed as the number of live births per 1,000 of the population per year.
Death rate is the ratio of total deaths to total population in a specified community or area over a specified period of time. The death rate is often expressed as the number of deaths per 1,000 of the population per year. Also called fatality rate.
Population Density
It is a measurement of population per unit area or unit volume; it is a quantity of type number density. It is frequently applied to living organisms, and most of the time to humans.
Environmental resistance
Environmental resistance is the limiting effect of environmental conditions on the numerical growth of a population.
Environmental resistance factors are things that limit the growth of a population. They lower the chances for reproduction, affect the health of organisms, and raise the death rate in the population. They include biotic factors like predators, disease, competition, and lack of food, as well as abiotic factors like fire, flood, temperature, wrong amount of sunshine ,and drought.
Environmental Resistance Factors
Food supply
As the population increases, the food supply, or the supply of another necessary resource , may decrease. When necessary resources, such as food , decrease, some individuals will die. Overall, the population cannot reproduce at the same rate, so the birth rates drop. This will cause the population growth rate to decrease.
Competition
When populations become crowded, organisms compete for food,water, space, sunlight and other essentials.
Predation
Populations in nature are often controlled by predation. The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanism of population control.
Parasitism and Disease
Parasites and disease can limit the growth of a population. A parasite lives in or on another organism (the host) and consequently harms it.
Natural disasters
Natural disasters such as droughts, floods, hurricanes, and fires, can all influence whatever populations are in the area at the time. Not only do these occurrences kill individuals in all populations, they also disrupt the availability of resources for survivors.
Biotic Potential
The biotic potential of a population is how well a species is able to survive.
While environmental resistance acts like a hill pushing back against population growth, biotic potential is what urges a population to grow. Biotic potential has to do with how well a species can survive, including how well adapted it is to the environment and its rate of reproduction. Some species produce a lot of young very often (while others produce fewer babies less often), but invest a lot of energy raising and protecting them. So while the biotic potential of a species causes the population to increase, environmental resistance keeps it from increasing relentlessly.
When the population is small, environmental resistance factors are, well, not as big of a factor. There may be plenty of resources around so the population can keep growing quickly. It's kind of like pushing a piece of gravel uphill rather than a boulder. But, as competition get stiffer and resources start to become limited, population growth starts to slow.
EFFECTS OF HUMAN ACTIVITIES TO THE NATURAL ECOSYSTEM
An ecosystem is comprised of communities of plants, animals and other organisms in a particular area that interact with each other and their surrounding environment. Both living and non-living things are considered part of an ecosystem.
Humans threaten ecosystems by producing waste and disposing them improperly, damaging habitats by logging forests, planting crops, construction of dams, conversion of agricultural lands into housing projects, using chemical base pesticides and fertilizers, and removing too many species without giving the ecosystem time to naturally regenerate.
Human activities that affect natural ecosystem
1. Introduction of Invasive Species
Invasive species are brought on by transporting species either intentionally or accidentally from other areas of the world. This can be devastating to existing species as invasive species are introduced on a time scale much more quickly than typically would happen with evolution over longer time periods. This can include outcompeting native species in the ecosystem, leading to the decline or extinction of local species, and overpopulation as these invasive species may not have any predators in this new ecosystem.
2. Overexploitation
Overexploitation is a major threat to ecosystems and therefore sustainability. It is the consumption of a natural resource at a rate greater than that natural resource can maintain itself.
• Overhunting
When humans overhunt key predators such as lions, tigers and bears, they remove the very animals that keep plant consumers in balance and prevent overgrazing. A healthy ecosystem has a balance of predators and prey that naturally cycle through life and death sequences. Over-hunting often results in ecosystem species imbalance and environmental stress.
• Overfishing
Humans also practice commercial overfishing , where massive fishing nets result in “bycatch,” in which unwanted fish are caught in nets and then thrown away. Bycatch results in the death of one million sharks annually. Large weights and heavy metal rollers that are used with the commercial fishing nets also drag along the bottom of the ocean, destroying anything in their path including fragile coral reefs.
• Overgrazing
It occurs when plants are exposed to intensive grazing for extended periods of time , or without sufficient recovery periods. It reduces the usefulness, productivity, and biodiversity of the land and is one cause of desertification and erosion.
• Illegal logging
Illegal logging contributes to deforestation, degrades forest environments, reduces biodiversity, and contributes to green gas emissions.
• Continuous cropping
Continuous cropping refers to a system in which certain crops are ‘‘replanted” in soils that had previously supported the same or similar plant species. Because of limited arable land sand expansive populations, continuous cropping systems are commonly practiced in the production of grain crops and cash crops. However, long-term continuous cropping usually leads to plant growth inhibition and serious soil-borne diseases. Continuous cropping can lead to soil exhaustion, erosion and low productivity if soil and nutrients conservation practices are not adopted. Excess fertilizers can be washed off by rain into bodies of water that could cause pollution
3. Pollution
Vehicles, trains and planes emit toxic gases that include carcinogenic particles and irritants, creating air pollution. Humans have also dumped large amounts of pesticides, such as organophosphates, onto crops that migrate into groundwater and bodies of water, poisoning ecosystems. Plants and animals die from exposure to pollutants such as excess nutrients from chemical fertilizers and other harmful chemicals. Pollution is increasing around the world and results in loss of biodiversity causing severe damage to self-sustaining ecosystems.
4. Habitat destruction
• Deforestation
Humans have always cut down trees throughout history. The world’s rainforests are being destroyed resulting in vegetation degradation, nutrient imbalance, flooding and animal displacement. Trees act as a natural air filter in the carbon cycle by taking in carbon dioxide and releasing oxygen, so deforestation contributes to global warming.
• Kaingin System
Kaingin system is the cutting down and burning of trees and plant growth in an area for cultivation purposes. Kaingin is a Filipino word that means clear-ing. Known as swidden farming in other countries, it is a traditional but destructive agricultural system practiced in many parts of the globe.
• Land Conversion
Through urban development, the continued rapid construction of road systems and buildings has changed the Earth's natural surface, removing soil nutrients, surface vegetation and trees that filter the air and equalize the carbon cycle. Urbanization also displaces animals and increases environmental pollution from vehicles and factories. A system of highways also causes migratory obstacles for animals and replaces native plants with impermeable concrete, resulting in habitat destruction. This practice of human construction continues at a rapid pace, leading to urban sprawl, where cities are essentially forever expanding outside the traditional inner-city limits.
THE EARTH SAVERS TEN COMMANDMENTS FOR SUSTAINABLE DEVELOPMENT
1. Thou shalt not throw garbage along canals, creeks or rivers.
2. Thou shalt not resort to destructive and illegal methods of fishing.
3. Thou shalt not resort to open burning methods to dispose your drug waste.
4. Thou shalt improve and maintain your care and vehicles in good running.
5. Thou shalt not smoke cigars and cigarettes .
6. Thou shalt minimize if not put to stop the use of CFC products.
7. Thou shalt not waste energy and water.
8. Thou shalt plant more trees and nurture them.
9. Thou shalt protect endangered species of plants and animals.
10.Thou shalt minimize if not totally stop the use of farm chemicals.