The United States Geological Survey estimates that (as of 2005, the most recent year for which data is available) we withdraw 410 billion gallons of water a day, including both fresh and saline water. Most (80%) of these withdrawals go to thermoelectric power plants (for cooling) and agriculture (for watering crops).
Level 4 is the hair color level that is represented as dark brown. It is one of the most common natural hair colors and also very commonly found in hair dye. Level 4 is also common in red or...
Two types of pigment give hair its color: eumelanin and pheomelanin. Pheomelanin colors hair orange and red. All humans have some pheomelanin in their hair. Eumelanin, which has two subtypes of black or brown, determines the darkness of the hair color. A low concentration of brown eumelanin results in blond hair, whereas a higher concentration of brown eumelanin results in brown hair.