Lecture 7

 Land pollution is the degradation of Earth's land surfaces often caused by human activities and their misuse of land resources. It occurs when waste is not disposed properly.  Health hazard disposal of urban and industrial wastes, exploitation of minerals, and improper use of soil by inadequate agricultural practices are a few factors.

 Land Pollution Comprises Of: 1. Solid Waste 2. Soil Pollution  Soil Pollution: Soil pollution is chiefly caused by chemicals in pesticides, and herbicides. Hence, soil pollution results from:  Unhealthy methods of soil management.  Harmful practices of irrigation methods.

 Soil contamination or soil pollution is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment.

 Urbanization and industrialization are major causes of land pollution. Urbanizationindustrialization  The Industrial Revolution set a series of events into motion which destroyed natural habitats and polluted the environment, causing diseases in both humans and other species of animals.

 The major increase in the concentration of population in cities, along with the internal combustion engine, led to the increased number of roads and all the infrastructure that goes with them.

 As the demand for food has grown exponentially with the increase of the human population, there is an increase in field size and mechanization.  When crops are harvested, the naked soil is left open to wind after it has been compacted by heavy machinery

 Another consequence of more intensive agriculture is the move to monoculture.  This is unnatural, will deplete the soil of nutrients, allows diseases and pests to spread and, as it happens, it quickly exhausts all the natural resources in an area, causing the introduction of chemical fertilizers and foreign substances to the soil that poisons it. The chemical fertilizers in the soil cause its infertility.

 A pesticide is a substance or mixture of substances used to kill a pest.  A pesticide may be a chemical substance, biological agent (such as a virus or bacteria), antimicrobial, disinfectant or device used against any pest.

 Pests include insects, plant pathogens, weeds, mollusks, birds, mammals, fish, nematodes (roundworms) and microbes that compete with humans for food, destroy property, spread or are a vector for disease or cause a nuisance.  Although there are benefits to the use of pesticides, there are also drawbacks, such as potential toxicity to humans and other organisms.

 Herbicides are used to kill weeds, especially on pavements and railways.  Most are biodegradable by soil bacteria.  However, one group derived from trinitrotoluene (2:4 D and 2:4:5 T) have the impurity dioxin, which is very toxic and causes fatality even in low concentrations.

 Another herbicide is Paraquat. It is highly toxic but it rapidly degrades in soil due to the action of bacteria and does not kill soil fauna.

 Insecticides are used to rid farms of pests which damage crops.  The insects damage not only standing crops but also stored ones and in the tropics it is reckoned that one third of the total production is lost during food storage

 There are now two main groups of synthetic insecticides ––  Organochlorines include DDT, Aldrin, Dieldrin and BHC. They are cheap to produce, potent and persistent.  Organophosphates, e.g. parathion, which is highly toxic, methyl-parathion is less so and Malathion is generally considered safe as it has low toxicity and is rapidly broken down in the mammalian liver.

 Modern mining projects leave behind disrupted communities, damaged landscapes, and polluted water.  Mining also affects ground and surface waters, the aquatic life, vegetation, soils, animals, and the human health.  Acid mine drainage can cause damage to streams which in return can kill aquatic life.  The vast variety of toxic chemicals released by mining activities can harm animals and aquatic life as well as their habitat.

 Mining gas and petroleum also pollutes the land. Petroleum extraction and manufacturing contaminates the soil with bitumen, gasoline, kerosene and mining brine solutions.  Opencast mining, which is a process where the surface of the earth is dug open to bring out the underground mineral deposits, destroys the topsoil and contaminates the area with toxic metals and chemicals.

 Waste management is the collection, transport, processing, recycling or disposal, and monitoring of waste materials.  The term usually relates to materials produced by human activity, and is generally undertaken to reduce their effect on health or the environment

 Solid Waste: Semisolid or solid matter that are created by human or animal activities, and which are disposed because they are hazardous or useless are known as solid waste.

Solid waste is classified as:  hazardous (radioactive, pesticides, medical, poisons) which is health and life threatening; or  non-hazardous (domestic, urban, mining, industrial, scrap metal.) which is unsightly and disposal takes up much space.

 Municipal solid waste (MSW), commonly known as trash or garbage, is a waste type consisting of everyday items we consume and discard. It predominantly includes food wastes, yard wastes, containers and product packaging, and other miscellaneous inorganic wastes from residential, commercial, institutional, and industrial sources.

 Municipal solid waste does not include industrial wastes, agricultural wastes, and sewage sludge.  The term residual waste relates to waste left from household sources containing materials that have not been separated out or sent for reprocessing

Following are the different types of wastes.  Biodegradable waste: food and kitchen waste, green waste, paper (can also be recycled).  Recyclable material: paper, glass, bottles, cans, metals certain plastics, etc.  Inert waste: construction and demolition waste, dirt, rocks, debris.  Composite wastes: waste clothing, Tetra Packs, waste plastics such as toys.  Domestic hazardous waste (also called "household hazardous waste") & toxic waste: medication, paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and pesticide containers, batteries, shoe polish.

 Hazardous waste presents immediate or long-term risks to humans, animals, plants, or the environment.  It requires special handling for detoxification or safe disposal.

In the U.S., hazardous waste is legally defined as any discarded solid or liquid that:  contains one or more of 39 carcinogenic, mutagenic, or teratogenic compounds at levels that exceed established limits (including many solvents, pesticides, and paint strippers);  catches fire easily (such as gasoline, paints, and solvents);

 is reactive or unstable enough to explode or release toxic fumes (including acids, bases, ammonia, and chlorine bleach); or  is capable of corroding metal containers such as tanks, drums, and barrels (such as industrial cleaning agents and oven and drain cleaners).

 Toxic waste is waste material that can cause death or injury to living creatures.  It spreads quite easily and can contaminate lakes and rivers.  The term is often used interchangeably with “hazardous waste”, or discarded material that can pose a long-term risk to health or environment.

 Toxic waste comes in many forms, such as liquid, solid, or sludge, and it contains chemicals, heavy metals, radioisotopes, dangerous pathogens, or other toxins.

 Toxic wastes often contain carcinogens, and exposure to these by some route, such as leakage or evaporation from the storage, causes cancer to appear at increased frequency in exposed individuals

Land pollution can affect wildlife, plants, and humans in a number of ways, such as:  Cause problems in the respiratory system  Cause problems on the skin  Lead to birth defects  Cause various kinds of cancers

The toxic materials that pollute the soil can get into the human body directly by:  Coming into contact with the skin  Being washed into water sources like reservoirs and rivers  Eating fruits and vegetables that have been grown in polluted soil  Breathing in polluted dust or particles