Environmental Science and Engineering Introduction

Topic 1: Introduction to Environmental Science and Engineering

• Environmental science brings together fields like ecology, biology, zoology, oceanography, atmospheric science, soil science, geology, and chemistry to study how natural and man-made processes interact and affect the Earth's biomes.
• Environmental engineering applies mathematics and science to utilize the properties of matter and sources of energy to solve environmental sanitation problems.

Ecosystems

• An ecosystem is a functional unit of nature where living organisms interact among themselves and with the surrounding physical environment.
• Ecosystems vary greatly in size, from small ponds to large forests or seas.
• The two basic categories of ecosystems are:
  • Terrestrial (forest, grassland, desert)
  • Aquatic (pond, lake, wetland, river, estuary)
• There are four levels of ecological organization:
  1. Population: all members of a species in a given location
  2. Community: all interacting populations in a given area
  3. Ecosystem: the living community and physical environment functioning together as an independent and relatively stable system
  4. Biosphere: the portion of the Earth where life exists, comprising numerous complex ecosystems

Major Components of Ecosystems

• Inorganic substances (C, N2, S, P, O2, CO2, H2O, etc.) involved in material cycles
• Organic compounds (proteins, carbohydrates, lipids, nucleic acids) that link biotic and abiotic components
• Climatic regime (temperature, humidity, sunlight, amount of water, etc.)
• Producers (autotrophic organisms) that manufacture food from simple inorganic substances
• Macro-consumers (phagotrophs or heterotrophic organisms) that eat or ingest other organisms or particulate organic matter
• Micro-consumers (saprotrophs or osmotrophs) that break down complex compounds of dead organisms

Human Influences on Ecosystems

• Human activities affect the environment, and the carrying capacity of the environment is limited by available abiotic and biotic resources and the ability of ecosystems to recycle residue.

Nutritional Relationships

• Autotrophs: can synthesize their own food from inorganic compounds and a usable energy source
• Heterotrophs: cannot synthesize their own food and are dependent on other organisms for their food
• Types of heterotrophs:
  • Saprophytes: live on dead matter (decomposers)
  • Herbivores: plant-eating animals
  • Carnivores: meat-eating animals
  • Omnivores: consume both plants and meat

Symbiotic Relationships

• Symbiosis: living together with another organism in close association
• Types of symbiosis:
  • Mutualism: both organisms benefit from the association
  • Parasitism: the parasite benefits at the expense of the host
  • Commensalism: one organism benefits and the other is unharmed

Food Chains and Food Webs

• Food chain: the transfer of energy from green plants through a series of organisms with repeated stages of eating and being eaten
• Food web: the flow of energy and materials in a natural community, with many interactions occurring along food chains

Biogeochemical Cycles

• The cycles of elements (carbon, oxygen, nitrogen, sulfur, phosphorus) through the Earth's systems (atmosphere, hydrosphere, biosphere, and lithosphere)
• These cycles are essential for life and are influenced by human activities.