Understanding Water Pollution: Sources and Impacts
Organic Contamination
Organic pollution can cause anoxic conditions, to the extent that only chemotrophs (reducing anaerobic bacteria) can persist. During anaerobic biodegradation, organic acids, alcohols, aldehydes, methane, hydrogen sulfide (H2S), and ammonia are produced. Intermediate compounds include phenols, indoles, and mercaptans. This results in a very high chemical oxygen demand (COD), which must be offset by dissolving oxygen (O2) in water. Organic contamination stems from the lack of
Read MoreEarth’s Structure, Forces, and Plate Tectonics
Earth’s Composition and Structure
Geology: The science of Earth.
- Continental Shelf (C-Shelf): Extends past the shoreline.
- Continental Crust (C-Crust): 35-40km average thickness, granite composition (light-grey).
- Oceanic Crust (O-Crust): 7km average thickness, basalt composition (dark), 46% O, 28% Si, 3gm/cm3.
- Mantle: 35% Fe, 30% O, 15% Si, 5g/cm3, extends to 2900km depth, upper (olivine), lower (same composition, higher pressure minerals).
- Core: 85% Iron (Fe), 11% Nickel (Ni), 4% Sulfur (S), 11gm/cm3
Forearm Muscles: Anatomy and Function
Anterior Group
Pronator Quadratus
It extends from the distal fourth of the ulna’s anterior face to the anteroexternal face of the distal fourth of the radius.
Function: Forearm pronation.
Flexor Digitorum Profundus
It originates from the proximal three-fourths of the ulna’s anterior face. It inserts via four tendons that pass through the wrist into the base of the third phalanx of the four ulnar digits.
Function: Flexion of the wrist, metacarpals, and third phalanges over the second ones.
Flexor Pollicis
Read MoreKey Concepts in Geography and Geology
Altitude
Altitude is the vertical distance of a point of land relative to sea level.
Dryness
Dryness is the lack of water in the soil and moisture.
Relief
Relief is the residual of an ancient horizontal platform or a slope, which testifies to its previous length. These hills have been cut off due to differential erosion caused by us and gullies.
Continental Climate
The continental climate is a factor due to a greater or lesser distance from the sea and the influence of land masses.
Mountain Range
A mountain
Read MoreUnderstanding Earth’s Dynamic Landscapes: From Debris Flows to Karst Formations
Understanding Earth’s Dynamic Landscapes
Debris Flows and Soil Creep
Debris flows are movements that involve large flows of regolith, with so much water that they could be categorized as quasi-river flows. If these flows transport abundant fine material, they are called earthflows. Soil creep, or simply creep, is a slow process that is sometimes the dominant evolutionary force in a field. Its driving force is gravity and is favored by seasonal changes in temperature, such as freeze-thaw cycles. Its
Read MoreEarthquakes and Volcanoes: Causes, Types, and Impacts
Earthquakes: Causes and Effects
Earthquakes occur when tension is released from inside the Earth’s crust. Tectonic plates do not always move smoothly alongside each other and sometimes get stuck. When this happens, pressure builds up. When this pressure is eventually released, an earthquake tends to occur.
- Magma rises through cracks or weaknesses in the Earth’s crust. Pressure builds up inside the Earth.
- When this pressure is released, e.g. as a result of plate movement, magma explodes to the surface