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  2. Trophic state index - Wikipedia

    en.wikipedia.org/wiki/Trophic_state_index

    The Trophic State Index (TSI) is a classification system designed to rate water bodies based on the amount of biological productivity they sustain. [1] Although the term "trophic index" is commonly applied to lakes, any surface water body may be indexed. The TSI of a water body is rated on a scale from zero to one hundred. [1]

  3. 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.

  4. 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.

  5. Eutrophication - Wikipedia

    en.wikipedia.org/wiki/Eutrophication

    Health problems can occur where eutrophic conditions interfere with drinking water treatment. [50] Phosphorus is often regarded as the main culprit in cases of eutrophication in lakes subjected to "point source" pollution from sewage pipes. The concentration of algae and the trophic state of lakes correspond well to phosphorus levels in water ...

  6. Chart datum - Wikipedia

    en.wikipedia.org/wiki/Chart_datum

    A chart datum is the water level surface serving as origin of depths displayed on a nautical chart and for reporting and predicting tide heights. A chart datum is generally derived from some tidal phase, in which case it is also known as a tidal datum. [1] Common chart datums are lowest astronomical tide (LAT) [1] and mean lower low water (MLLW).

  7. Plant nutrients in soil - Wikipedia

    en.wikipedia.org/wiki/Plant_nutrients_in_soil

    Nutrients in the soil are taken up by the plant through its roots, and in particular its root hairs.To be taken up by a plant, a nutrient element must be located near the root surface; however, the supply of nutrients in contact with the root is rapidly depleted within a distance of ca. 2 mm. [14] There are three basic mechanisms whereby nutrient ions dissolved in the soil solution are brought ...

  8. Lake Langdon - Wikipedia

    en.wikipedia.org/wiki/Lake_Langdon

    Though the lake's MCWD Report Card shows a significant drop off of the phosphorus levels over the past 20 years, it is still a problem. A higher outflow from Langdon could lower the phosphorus level, but its water clarity remains poor, despite the fact that it was treated with Alum in 1998.

  9. Boiling points of the elements (data page) - Wikipedia

    en.wikipedia.org/wiki/Boiling_points_of_the...

    Group → 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18; ↓ Period 1: H 2 20.271 K (−252.879 °C) He 4.222 K (−268.928 °C) 2: Li 1603 K (1330 °C) Be 2742 K ...