Hydrosphere and Bioaccumulation

Water Cycle:

• All water on Earth continuously cycles through ecosystems by the interaction of three main processes through solar energy and gravity

  • Evaporation: Heat from the Sun causes water at Earth’s surface to evaporate

  • Condensation: As warm air rises, it cools and condenses, forming clouds

  • Precipitation: Water falls back to Earth’s surface when it rains or snows

• Run off: Water moves over Earth’s surface and moves downhill back into the ocean water due to gravity and moves downhill back into the ocean water

Transpiration:

• Water moves through the biosphere through transpiration

• Process which water is absorbed by the roots of plants, carried through plant and lost as water vapour through small pores in the leaves

Water Distribution:

• Small portion of the water in the hydrosphere is fresh (less than 1%）

  • Ex. Precipitation, rivers, streams, groundwater, frozen glacier

• 97% of Earth’s water is salty (oceans)

• Ice (more than 2%)

Ocean currents (Surface Currents)

• Ocean currents also redistribute thermal energy and nutrients around Earth

• Surface currents are created by wind

• Warm currents: move heat (warm water from the equator) towards the poles (higher colder latitudes

• Cold currents: bring cold water from colder, higher latitudes to tropical regions

The Great Ocean Conveyer Belt

• Massive system of deep water currents

• Moves deep water, heat, and nutrients around Earth

• Movement of currents is based on differences between the temperature and salt content of water

  • Cold water is denser than warm water

  • Cold water sinks and displaces the warm water

  • Saltier water is more dense than less salty water

  • Saltier water sinks and displaces less salty water

• Also moves nutrients such as nitrogen and phosphorus

  • Surface water that sinks is not nutrient poor

  • After the water sinks, bacteria in deep water break down organic material and return nutrients to the water

  • When the deep water returns to the surface, it has a high concentration of nutrients

Water pollution:

• A physical, biological, or chemical change in water quality that harms organisms or makes water unuseable

• Major problem: Synthetic (human made) chemicals and pollutants enter the environment in air, water and soil,

• Decomposers cannot break them down through the biodegradation process so they stay in the environment for a long time

Sources of water pollution:

• Point sources

  • Examples: factories, power plants, sewage treatment plants, oil wells

  • Easy to monitor and regulate

• Non-point sources

  • Examples: run off from farms, lawns, construction sites, logging areas, roads, parking lots

  • Difficult to monitor, regulate and treat since pollution is regularly repeating

Bioaccumulation:

• The gradual buildup of chemicals and pollutants in cells and tissues of organisms

• Accumulation: chemical taken up and stored faster than it is broken down or excreted via. Food intake, skin contact or respiration

• Ex. Algae toxins from red tide taken by clams and human shellfish

• PCBs accumulating in orcas and raptors

• DDT affecting birds of prey

• Can cause birth defects and damage body systems

Biomagnification:

• Increase in concentration of pollutants in tissues of organisms in higher levels of a food chain or web

  • Because they eat many smaller contaminated organisms, concentrating the toxins further

Bioremediation:

• method that uses living organisms to help clean up chemical pollution naturally

  • Ex. Some microorganisms naturally feed on chemicals and reduce them to non toxic compounds

  • Plants can act as stabilizers to contaminated soil, reducing wind water erosion that could spread contaminants