MATSEC IM Environmental Science cheat sheet

Earth's four interacting spheres are the atmosphere (gases), hydrosphere (water), lithosphere (rock and soil) and biosphere (living organisms); a change in one sphere alters fluxes in the others.

Surface energy balance: net radiation = incoming solar − reflected solar − outgoing longwave; absorbed energy drives sensible heat, latent heat (evaporation) and photosynthesis.

Albedo is the reflected fraction of incoming solar radiation; fresh snow is about 0.8–0.9, forest about 0.1–0.2 and open ocean about 0.06; higher albedo generally cools the surface.

In the troposphere temperature falls at an average environmental lapse rate of about 6.5 °C/km; air pressure falls with altitude, and rising air cools to the dew point, forming cloud.

Global circulation cells are Hadley (equator to about 30°), Ferrel (about 30–60°) and Polar (about 60–90°); Coriolis deflection creates trade winds, westerlies and polar easterlies.

Hydrological cycle stores and fluxes include ocean evaporation, atmospheric transport, precipitation, interception, infiltration, groundwater flow, runoff and evapotranspiration; rivers return water to oceans.

Rock cycle: igneous rocks crystallise from magma; weathering and erosion produce sediment; compaction and cementation form sedimentary rock; heat and pressure form metamorphic rock; melting returns magma.

Biogeochemical cycles: carbon has atmospheric CO2, oceanic, fossil and biotic pools; nitrogen requires fixation, nitrification and denitrification; phosphorus has no atmospheric gas phase and is often limiting.

Energy flows one way through ecosystems, whereas nutrients cycle; sunlight is captured by producers, transferred to consumers and lost mainly as heat via respiration.

Trophic efficiency is typically about 10%; this explains why food chains rarely exceed four or five trophic levels and why top predators need large areas.

NPP = GPP − respiration; net primary productivity is the organic matter available to consumers and decomposers and can be expressed as energy per area per time.

Exponential growth is dN/dt = rN, where r is the intrinsic rate of increase; logistic growth is dN/dt = rN(1 − N/K), where K is carrying capacity.

Density-dependent factors such as food, disease, predation and space intensify as population rises; density-independent factors such as fire, storm and drought affect populations regardless of density.

Species interactions include competition (−/−), predation and parasitism (+/−), mutualism (+/+) and commensalism (+/0); the competitive exclusion principle states that complete competitors cannot coexist indefinitely.

Biodiversity includes genetic, species and ecosystem diversity; high biodiversity can increase resilience, and habitat loss and invasive alien species are major threats.

Maltese habitats include garigue, maquis, steppe, coastal cliffs, saline marsh, sand dunes, islets and Posidonia oceanica seagrass meadows; endemic examples include the Maltese rock-centaury and Maltese wall lizard.

IPAT: Impact = Population × Affluence × Technology; reducing any factor can lower impact, but the factors interact and technology can be either damaging or corrective.

Demographic transition: high stationary → early expanding (death rates fall) → late expanding (birth rates fall) → low stationary; population momentum can cause growth after fertility declines.

Water stress is assessed as freshwater availability per person; Malta relies heavily on desalination and groundwater, and over-abstraction can cause saline intrusion in coastal aquifers.

Energy sources are renewable (solar, wind, hydro, biomass, geothermal, marine) or non-renewable (coal, oil, gas, nuclear fuel); EROI compares energy returned to energy invested.

Waste hierarchy decision order: prevent, reuse, recycle, recover energy, then dispose; sanitary landfill is the last option, and methane capture reduces its greenhouse impact.

Pollution classification: point source has an identifiable outlet; non-point source is diffuse. Persistent, fat-soluble pollutants can bioaccumulate and biomagnify.

Land-use impacts: urban sprawl increases sealed surfaces, runoff, car dependence and habitat fragmentation; agriculture can cause soil erosion, nitrate leaching and pesticide pollution.

A carbon footprint is total greenhouse gases expressed as CO2 equivalent; key gases include CO2, methane, nitrous oxide and fluorinated gases with different global warming potentials.

Brundtland definition: sustainable development meets present needs without compromising future generations; it integrates environmental, social and economic dimensions.

Environmental principles: precaution (act despite uncertainty), prevention (stop harm at source), polluter pays (costs internalised) and proximity (treat waste near its source).

EIA sequence: screening → scoping → baseline study → impact prediction and significance → mitigation → reporting → decision → monitoring and audit.

Malta's Environment Protection Act (Cap. 549) provides the main framework; the Environment and Resources Authority regulates environmental permits, protected areas and EIA.

Natura 2000 comprises Special Protection Areas under the Birds Directive and Special Areas of Conservation under the Habitats Directive; Malta designates terrestrial and marine sites.

Conservation approaches: in situ protection (species in natural habitat, such as nature reserves) and ex situ protection (seed banks, captive breeding); in situ is generally preferred for ecosystem function.

Circular economy keeps materials in use through reuse, repair, remanufacturing and recycling; it reduces waste, energy demand and raw-material extraction compared with a linear economy.

Environmental economics tools: externalities are uncompensated third-party costs; taxes, charges, tradable permits and subsidies can internalise them; cost-benefit analysis compares discounted costs and benefits.