Environmental Science: Human Impact & Sustainability

What are the four primary greenhouse gases (GHGs) that contribute to the anthropogenic greenhouse effect?

The four primary greenhouse gases are Carbon Dioxide (CO2), Methane (CH4), Nitrous Oxide (N2O), and Fluorinated gases (such as CFCs and HFCs). Water vapor is also a GHG but is primarily naturally regulated.

Which international agreement was specifically designed to phase out the production and consumption of ozone-depleting substances like chlorofluorocarbons (CFCs)?

The Montreal Protocol (1987) is the international treaty designed to protect the ozone layer by phasing out substances responsible for ozone depletion.

In the 'Reduce, Reuse, Recycle' hierarchy of waste management, why is 'Reduce' considered the most sustainable option?

Reducing is most sustainable because it prevents the generation of waste at the source, thereby eliminating the energy and resources required for production, transport, and eventual disposal or recycling.

What is the fundamental difference between a primary air pollutant and a secondary air pollutant?

A primary pollutant is emitted directly from a source (e.g., CO from a tailpipe), while a secondary pollutant forms in the atmosphere through chemical reactions between primary pollutants and other compounds (e.g., ground-level ozone).

How does deforestation contribute to the increase of atmospheric CO2 levels through two distinct mechanisms?

Deforestation increases CO2 by removing 'carbon sinks' (trees that perform photosynthesis) and by releasing stored carbon into the atmosphere when the biomass is burned or decomposes.

Which renewable energy source utilizes the kinetic energy of moving water to rotate a turbine and generate electricity?

Hydroelectric power (or Hydropower) uses the kinetic energy of flowing or falling water to drive turbines connected to generators.

Explain the chemical process of ocean acidification and its specific impact on marine calcifying organisms.

CO2 dissolves in seawater to form carbonic acid (H2CO3), which dissociates into hydrogen ions (H+) and bicarbonate. The increase in H+ lowers the pH and reacts with carbonate ions (CO3^2-), making them less available for organisms to build calcium carbonate (CaCO3) shells.

Describe the 'Albedo Effect' as a positive feedback loop in the context of melting Arctic sea ice.

As Arctic ice melts, highly reflective white surfaces (high albedo) are replaced by dark ocean water (low albedo). The dark water absorbs more solar radiation, increasing local temperatures and causing further ice melt, which accelerates the warming cycle.

What are the necessary precursors and environmental conditions required for the formation of photochemical smog?

Photochemical smog requires Nitrogen Oxides (NOx), Volatile Organic Compounds (VOCs), and intense sunlight. These react to form secondary pollutants like ground-level ozone (O3) and peroxyacetyl nitrates (PANs).

Define 'Eutrophication' and outline the sequence of events that leads to the formation of a 'dead zone' in aquatic ecosystems.

Eutrophication is nutrient over-enrichment (N and P). This triggers an algal bloom; when the algae die, aerobic bacteria decompose them, consuming dissolved oxygen. This leads to hypoxia (low oxygen), creating a 'dead zone' where fish cannot survive.