INDUSTRIAL & ENVIRONMENTAL BIOTECHNOLOGY
Course # KIBGE-707
AFSHEEN AMAN, Ph.D.Assistant Professor
Industrial Biotechnology SectionDr. A.Q. Khan Institute of Biotechnology & Genetic
Engineering (KIBGE)University of Karachi
Pakistan
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BIOAVAILABILITY & TOXICITY OF POLLUTANTS
Course # KIBGE-707
ECOTOXICOLOGYThe term ecotoxicology was coined by
Rene Truhaut in 1969
Branch of toxicology concerned with the study of toxic effects, caused by natural or synthetic pollutants, to the constituents of ecosystems, animals (including human), vegetables and microbes”
Ecology in the presence of toxicants3
A 5-steps understanding process useful for research/regulation
• Release of pollutant into the environment• Transport and fate into biota (with/out chemical transformation)• Exposure to biological and ecological system• Understanding responses and/or effects (molecular to ecological systems)• Design experiments, remediation, minimization,
conservation, and risk assessment plans tounderstand, eliminate, prevent or predict
environmental and human health pollutions situations.
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Ecotoxicity • Subject of study of the field of ecotoxicology refers to the potential for biological, chemical or physical stressors to affect ecosystems.
Such stressors might occur in the natural environment at densities, concentrations or levels high enough to disrupt the natural aspects that comprise the ecosystem.•Biochemistry•Physiology •Behavior•Interactions of the living organisms 5
Bioavailability of a pollutant
The extent to which a pollutant is available to living things. Some compounds are very bioavailable to plants and animals because they are soluble in water; different compounds are soluble to different degrees.
If a substance is insoluble in water, or hydrophobic, it is generally not bioavailable.
Hydrophobic compounds have an affinity for lipids and thus do not associate with water.
Bioavailability will vary with soil structure and organic matter content.
The higher the clay content of a soil, the more likely a pollutant is to be bound to the soil and therefore unavailable for plant uptake.
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Clay soils have a smaller particle size, and thus more surface area. This high surface area provides for more exchange sites.
Organic compounds that have a charge are subject to these exchange sites and become less bioavailable.
High organic matter content in the soil will bind lipophilic (i.e. hydrophobic) compounds, making petroleum hydrocarbons less available. 8
TYPES OF POLLUTANTSGreenhouse Gases: Carbon dioxide and methane are two of the
most important of these gases, called greenhouse gases because they trap heat in the earth's atmosphere.
This is already causing severe problems around the world and the situation will only get worse.
The rising temperatures will likely lead to more severe weather events, cause shifts in natural communities, and probably lead to greater species extinction rates, among numerous other effects.
Pesticides: A broad group of chemicals that enable
us to live more comfortable lives by and large, but whose main purpose underlies the central problem with pesticide pollution.
A lot of these chemicals will wash into our rivers and streams and cause direct toxicity to fishes, and may work their way up the food chain to affect birds, bears, whales, and other predatory wildlife, including humans.
InsecticidesFungicidesHerbicides
Plant-growth regulator Other compound
They are all poisons
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Some of these pesticides will persist for long periods of time in the environment.
DDT was a pesticide used for along time in the US (and is still being used in parts of the world for mosquito control), but has been banned in the US since 1972.
Yet we still find DDT in our environment, sometimes at very high levels.
Heavy metals:Metals are continuously released into the
biosphere by volcanoes, natural weathering of rocks but also by numerous anthropogenic acitivities, such as mining, combustion of fuels, industrial and urban sewage and agricultural practices.
On a global scale there is now abundant evidence that anthropogenic activities have polluted the environment with heavy metals from the poles to the tropics and from the mountains to the depths of the oceans. 13
Most heavy metals, such as mercury, are a natural part of the earth's crust, and would be slowly released into the environment over time just by weathering of soils and rocks.
However, our consumption of fossil fuels has greatly increased the introduction of heavy metals into our environment.
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The world-wide emissions of metals to the atmosphere by natural sources is estimated as (thousand t yr-1):
Ni: 26, Pb: 19, Cu: 19, As: 7.8, Zn: 4, Cd: 1.0, Se: 0.4
Whereas, from anthropogenic sources (thousand t yr-1):
Pb: 450, Zn: 320, Ni: 47, Cu: 56, As: 24, Cd: 7.5, Se: 1.1 15
It is estimated that half of the mercury introduced into the environment today is due to human sources.
The problem is mercury, as well as other heavy metals, that cannot be detoxified.
Once it is in the environment, it is here for good. Toxic effects of heavy metals vary.
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Mercury is a potent toxin in people targeting nervous tissue, but targets other tissues in other animals.
The effects of heavy metals can also be quite severe, since plants and animals have no natural ability to deal with heavy metals specifically and heavy metals do not have any functions in our bodies.
List of Environmental Issues Climate change — Global warming • Fossil
fuels • Sea level rise • Greenhouse gas • Ocean acidification
Conservation — Species extinction • Pollinator decline • Coral bleaching • Holocene extinction event • Invasive species • Endangered species
Dams — Environmental impacts of dams Energy — Energy conservation •
Renewable energy • Efficient energy use • Renewable energy commercialization
Intensive farming — Overgrazing • Irrigation • Monoculture • Environmental effects of meat production
Land degradation — Land pollution • Desertification
Soil — Soil conservation • Soil erosion • Soil contamination • Soil salination
Land use — Urban sprawl • Habitat fragmentation • Habitat destruction
Nanotechnology — Nanotoxicology • Nanopollution
Nuclear issues — Nuclear fallout • Nuclear meltdown • Nuclear power • Radioactive waste
Overpopulation — Burial Ozone depletion — CFC
Toxins — Chlorofluorocarbons • DDT (dichlorodiphenyltrichloroethane) • Endocrine disruptors • Dioxin • Heavy metals • Herbicides • Pesticides • Toxic waste • Bioaccumulation
Waste — E-waste • Litter • Waste disposal incidents • Marine debris • Landfill • Recycling • Incineration
Genetic engineering — Genetic pollution • Genetically modified food controversies
THANK YOU
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