Human Influences On The Environment

It dissolves in water to make it acidic, leading to acid rain.

CO has a stronger affinity than O2 for haemoglobin, meaning that the haemoglobin binds more strongly with the CO than with oxygen. This means less oxygen can be transported around the body and may lead to asphyxiation.

Sulfur is found in impurities in fuels, and burns in O2 when the fuel burns to form SO2

Formed when carbon compounds are burned in a limited supply of O2

The deprivation of O2

In car engines, the heat and pressure are high enough to cause N2 and O2 in the air to react together.

• as rain flows into lakes and rivers, their water becomes more acidic, meaning that fish can have trouble breathing and, consequently, die • causes soil leaching, meaning that the soil loses some of its nutrients, so tree roots become stunted and trees are more at risk of diseases and frost • can damage stonework, especially limestone by dissolving it.

They dissolved in water to make it acidic, leading to acid rain

the introduction of harmful substances or heat into the environment (air, water, or land) that cause undesirable effects on organisms and ecosystems

• carbon dioxide • carbon monoxide • sulfur dioxide • nitrogen oxides • methane • CFCs

organisms that show pollution levels by their presence or absence.

• small moss-like organisms. They act as indicators for SO2 as different types have varying tolerances to SO₂ levels. In polluted areas, only hardy, crusty lichens survive, while areas with clean air support more diverse and abundant leafy or bushy lichens.

Greenhouse gases in the atmosphere trap the heat energy from the sun which is reflected off the Earth’s surface. Instead of escaping into space, the heat energy warms the Earth.

Increased concentration of greenhouse gases causing an increased greenhouse effect, making the Earth warmer than it should be

CO2 is produced in the complete combustion of fuels containing carbon. E.g. when hydrocarbons are burned in power stations

• Reduced CO₂ absorption: Fewer trees → less photosynthesis → less CO₂ removed → imbalance of gases → disrupts the carbon cycle. • Reduced O₂ production: Less autotrophic activity → less oxygen for respiration → contributes to atmospheric gas imbalance. • Reduced soil fertility: Fewer leaves fall → less organic matter/nitrates returned to soil → soil less fertile. • Changes in water cycle / increased flooding: Normally 25% of rainfall is absorbed by foliage or evaporates and 50% by roots. Fewer trees → water accumulates rapidly → landslides more likely. • Disrupted evapotranspiration: Less transpiration → slower evaporation → drier atmosphere → reduced rainfall → affects water cycle. • Leaching of minerals: Without trees, heavy rainfall washes soluble nutrients (nitrates, minerals) out of the soil → further reduces fertility. • Local climate changes: Bare soil absorbs heat → warms lower atmosphere → thermal gradients → more frequent/intense winds. • Loss of habitat / biodiversity: Many species depend on forests (e.g., mountain gorilla) → populations decline. • Soil erosion: Without roots and canopy, wind and rain remove soil → soil structure destabilised → erosion.

Methane is produced when microorganisms break down organic matter in anaerobic conditions. This happens in places such as waterlogged soils, rice fields, landfill sites and in the digestive systems of cows

An increase in the average temperature of the Earth’s surface

The enhanced greenhouse effect happens when human activities (like burning fossil fuels, deforestation, and farming) increase the concentration of greenhouse gases such as carbon dioxide and methane in the atmosphere. These gases trap more heat energy from the Sun by absorbing infrared radiation that would otherwise escape into space. This extra trapped heat causes the Earth’s average temperature to rise — this is global warming

• melting of the polar ice caps, causing a rise in sea level, which may threaten many cities such as London, New York and Amsterdam • weather patterns will change with more unusual weather • tropical diseases may become more common in other regions, such as Europe • change in distribution of pests that attack crops, which will have an impact on food security in some areas

The progressive enrichment of a water body with minerals which ultimately leads to a decrease in oxygen levels and the death of aquatic organisms.

• Inorganic fertilisers contain soluble nitrates and phosphates. • Soluble fertilisers are easily leached from soil into rivers and lakes by rainwater. • Excess nutrients in water cause eutrophication. This means: • Rapid algal growth (algal bloom) occurs. • Algae multiply rapidly, forming a blanket on surface of water- blocking sunlight → submerged aquatic plants cannot photosynthesise and die. • Algae compete with each other for space and resources → many algae die. • Large volumes of dead plant material at the bottom of the water and dead algae at the surface provide organic matter for bacteria. • Bacteria respire while decomposing this material → oxygen in water is used up. • Water becomes anoxic (lacking oxygen). • Fish and other aquatic animals suffocate and die.

• Sewage contains organic matter and harmful microorganisms. • Sewage enters rivers and lakes, adding large amounts of organic matter to the water. • The organic matter provides food for bacteria. • Bacteria respire while decomposing the organic matter, using up oxygen in the water. • The dissolved oxygen concentration falls, and the water can become anoxic. • Fish and other aquatic animals suffocate and die due to lack of oxygen.

The cutting down of trees to clear the land for human use