Human Influences on Environment

Human Influences on Environment

1. Water Pollution

   • Fertilisers
     • Eutrophication
       • minerals are leached from the soil
         • minerals speed up the growth of algae in slow-moving waterways
           • increased competition means that most of the algae die
             • dead algae is decomposed by decomposers
               • these decomposers multiply rapidly and use up all the oxygen for respiration
                 • this creates anoxic (anaerobic) conditions causing many aquatic organisms to die
                   • e.g. Fish
   • Toxic Chemicals
     • Biomagnification
       • Some chemicals are non-biodegradeable and persist in the environment
         • if they accumulate to high enough concentrations they become toxic
           • they build up in the food chain reaching lethal concentrations in the top predators
             • e.g. DDT persists in the fatty tissues of the osprey - every time it eats a fish it gains a repeat dose of the pesticide - accumulation
       • it happens because each organism in a food chain eats many of the preceding organisms in the chain

2. Air Pollution

   • Sulfur Dioxide
     • Mainly Produced by Power Stations
     • Acid Rain
       • Pollution of Water
         • Kills aquatic organisms
           • e.g. Fish
       • Erosion of Buildings
       • Leaching Minerals
     • can be measured using lichen
       • crusty lichen=high S02 concentrations
       • shrubby lichen=low S02 concentration
   • Carbon Monoxide
     • Mainly Produced by cars
       • smoking
     • Harms humans
       • able to bind with haemoglobin
         • can die from lack of oxygen
   • Greenhouse Gases
     • e.g. Water Vapour, C02, Nitrous Oxide, Methane and CFCS
     • occurs because the greenhouse gases transmit and absorb different wavelengths of radiation
       • greenhouse gases allow short-wave radiation through (mostly visible light)
         • the earth absorbs this radiation and warms up
           • the hot earth radiates long-wave radiation (infared)
             • greenhouse gases absorb this radiation causing the atmosphere to warm up
               • some of this energy is reradiated back to earth causing the earth to warm up

3. Deforestation

   • Definition: Where natural forests are cleared through logging and/or burning, either to use the timber or replace the area for alternative uses
   • Impacts
     • Increase leaching due to more surface run off
     • accelerated rate of soil erosion due to increasing surface run off, reducing soil protection from tree litter and there are no tree roots to bind the soil together
     • Drier climate due to reduced levels of transpiration and trees no longer absorb groundwater
     • More CO2 in the atmosphere relative to O2 because no photosynthesis is taking place