final unit 4

Unit 4

• Weather: the state of the atmosphere with respect to wind, temperature, cloudiness, moisture, pressure, etc. •

•  Climate: the long-term pattern of temperature and precipitation averages at a location

• The greenhouse effect: a natural process that occurs when greenhouse gases in a planet's atmosphere trap heat from the sun, warming the planet's surface and lower atmosphere

Greenhouse effect

• Carbon dioxide • Increases due to deforestation and burning fossil fuels

• Methane • Increases largely due to agricultural practices, landfills, and thawing tundra

• Nitrous oxide • Increases largely due to oxidation of nitrogen- containing compounds from burning fossil fuel

• Chlorofluorocarbons (CFCs) • Synthetic compounds used as refrigerants, cleaning solvents, fire retardants, and manufacturing of foam products

• Black carbon: particles released to the atmosphere from burning that directly absorb sunlight and heat the atmosphere

• Consequences of Climate Change 

  • Climate patterns are changing • Drier and wetter depending on region • 

  • Storms and fires more frequent and more severe • 

  • Melting glaciers and ice sheets • 80%+ of Earth's glaciers retreating •

  •  Rising sea levels • Thermal expansion • Glacial meltwater (but not from sea ice) •

  •  Changing populations and ecosystems

• Changing populations and ecosystems • Climate cues for animal migration and hibernation • Food chains/webs may change • Spread of tropical diseases

• Renewable energy: • Energy derived from sources that are not depleted when they are used or are replenished in a short amount of time

• Air quality: gases and small particles in atmosphere that influence ecosystems or human well-being •

•  Pollution: the addition of any substance (solid, liquid, or gas) or any form of energy (such as heat, sound, or radioactivity) to the environment at a rate faster than it can be dispersed, diluted, decomposed, recycled, or stored in some harmless form •

•  Air pollution: gases or particles that are high enough concentrations to harm humans, organisms, or structures

• Primary air pollutants: chemicals or particles directly released in air • Secondary air pollutants: chemicals and particles that are formed by reaction of other chemicals or aerosols in the atmosphere

• Point source • Stationary, localized sources • Smokestacks, etc. • Can produce a large amount of pollution • 

• Non-point source • Numerous sources that produce a relatively small amount individually; collectively it adds up quickly

• Hydrologic cycle: the continuous movement of water between the Earth's atmosphere, land, surface water, and groundwater • Over 70% of Earth's surface is covered with water • Equal amount of water evaporates as precipitates

• Residence time of water: the average time a water molecule resides in that part of the cycle

• • Watershed: area of land that drains to form a river or lake • Also called drainage basins • Separated by geological features • Mountains, plateaus 

• • Open watersheds: eventually drain to sea •

•  Closed watersheds: do not drain to sea

• Baseline water stress: total annual water withdrawals as a percentage of annual flow in that region

• Recharge zone: area from which water enters water table from surface 

• Discharge zone: groundwater flows to surface 

• Unconfined aquifers: located beneath recharge zones 

• Confined aquifers: trapped between impermeable rock or sediment

• Groundwater: water that resides in rocks and soil beneath the ground • 

• Most is in aquifers: layers of sediment and rock saturated with water 

• Zone of aeration: rocks and sediments not saturated with water (also called unsaturated zone) 

• Water table: underground depth were rocks and sediment are saturated with water 

•  Zone of saturation: rocks and sediments that are completely saturated with water

• Subsidence: sinking of land above an aquifer • May occur slowly • May occur quickly 

•  Saltwater intrusion: migration of saltwater into freshwater aquifers

• Impervious surfaces: a hard area that prevents water from soaking into the ground, mainly artificial • Pavement, roofs • Do not absorb rainfall

• Point pollution: water contamination that comes from a single, identifiable source, such as a pipe; is a direct “pipe” to a body of water

• Water Pollution 3 Charateristics

  • Physical • Turbidity, sediment 

  • Biological • Bacteria, pathogens 

  • Chemical • Industrial discharge, pharmaceuticals, personal care products

• Non-point pollution: is defined to mean any source of water pollution that does not meet the legal definition of "point source

• Bioassessment: using organisms living in the water as an indicator of quality

• Eutrophication the process where a water body receives excessive amounts of nutrients, like nitrates and phosphates, leading to an overgrowth of algae and plants

• Energetics • Agroecosystems funnel energy into plants and animals useful to humans • Simple food chain • 

• Harvest index: fraction of total production that can be used by humans

• trophic-level efficiency than wild animals (10%) due to selective breeding and easier to digest feed 

• Trophic level efficiency: the fraction of energy that an animal consumes that is converted into biomass

• Agroecosystems: crops and domesticated animals, the physical environment, and other organisms associated with them 

• Agroecology: the science of managing farms as ecosystems; work with nature, not against it

• Soil fertility: refers to ability of soil to support plant growth

• Preventing soil erosion • Best practices: 

  • • Prevent erosion on uneven ground and from wind • 

  • Keep soil covered •

  •  Disturb soil as little as possible • 

  • Keep plants growing all year to feed soil • 

  • Crop rotation and cover crops

• Irrigation: the watering of land by artificial means to foster plant growth by water diversion and pumping

• soil salination: the buildup of salts in the soil, primarily due to irrigation and high evaporation rates

• Biological pest control: use of microbes, predators, and parasites to control pests