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  2. Abundance of elements in Earth's crust - Wikipedia

    en.wikipedia.org/wiki/Abundance_of_elements_in...

    The composition of the Earth changed after its formation due to loss of volatile compounds, melting and recrystalization, selective loss of some elements to the deep interior, and erosion by water. [ 3 ] : 55 The lanthanides are especially difficult to measure accurately.

  3. Trophic state index - Wikipedia

    en.wikipedia.org/wiki/Trophic_state_index

    The TSI of a water body is rated on a scale from zero to one hundred. [1] Under the TSI scale, water bodies may be defined as: [1] oligotrophic (TSI 0–40, having the least amount of biological productivity, "good" water quality); mesotrophic (TSI 40–60, having a moderate level of biological productivity, "fair" water quality); or

  4. Hardnesses of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Hardnesses_of_the_elements...

    This page was last edited on 16 November 2024, at 12:16 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.

  5. Dead zone (ecology) - Wikipedia

    en.wikipedia.org/wiki/Dead_zone_(ecology)

    From 2015-2019, 11 different conditions were measured in various areas of the Elizabeth River. Throughout the river, there were consistently high levels of nitrogen and phosphorus, along with high levels of other contaminants contributing to the poor quality of life for bottom feeders along the river.

  6. Phosphorus - Wikipedia

    en.wikipedia.org/wiki/Phosphorus

    The predominant source of phosphorus in modern times is phosphate rock (as opposed to the guano that preceded it). According to some researchers, Earth's commercial and affordable phosphorus reserves are expected to be depleted in 50–100 years and peak phosphorus to be reached in approximately 2030.

  7. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.

  8. List of gases - Wikipedia

    en.wikipedia.org/wiki/List_of_gases

    This is a list of gases at standard conditions, which means substances that boil or sublime at or below 25 °C (77 °F) and 1 atm pressure and are reasonably stable. List [ edit ]

  9. Water distribution on Earth - Wikipedia

    en.wikipedia.org/wiki/Water_distribution_on_Earth

    Typically, fresh water is defined as water with a salinity of less than 1% that of the oceans – i.e. below around 0.35‰. Water with a salinity between this level and 1‰ is typically referred to as marginal water because it is marginal for many uses by humans and animals. The ratio of salt water to fresh water on Earth is around 50:1.