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  2. Soil guideline value - Wikipedia

    en.wikipedia.org/wiki/Soil_guideline_value

    Soil Guideline Values (SGVs) are figures which are used in non-statutory technical guidance for assessors carrying out risk assessments to determine whether land is considered "contaminated" under United Kingdom law, that is "land which appears to... be in such a condition, by reason of substances in, on or under the land, that (a) significant harm is being caused or there is a significant ...

  3. Parts-per notation - Wikipedia

    en.wikipedia.org/wiki/Parts-per_notation

    As the concentration increases the colour becomes a more vibrant yellow, then orange, with the final 10,000 ppm a deep red colour. In science and engineering , the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities , e.g. mole fraction or mass fraction .

  4. Soil quality - Wikipedia

    en.wikipedia.org/wiki/Soil_quality

    Soil quality reflects how well a soil performs the functions of maintaining biodiversity and productivity, partitioning water and solute flow, filtering and buffering, nutrient cycling, and providing support for plants and other structures. Soil management has a major impact on soil quality. Soil quality relates to soil functions. Unlike water ...

  5. Unified Soil Classification System - Wikipedia

    en.wikipedia.org/wiki/Unified_Soil...

    The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt):

  6. USDA soil taxonomy - Wikipedia

    en.wikipedia.org/wiki/USDA_soil_taxonomy

    About 1,000 soil subgroups are defined in the United States. [6] A soil family category is a group of soils within a subgroup and describes the physical and chemical properties which affect the response of soil to agricultural management and engineering applications. The principal characteristics used to differentiate soil families include ...

  7. Air pollution measurement - Wikipedia

    en.wikipedia.org/wiki/Air_pollution_measurement

    Measuring air pollution is the first step in identifying its causes and then reducing or regulating them to keep the quality of the air inside legal limits (mandated by regulators such as the Environmental Protection Agency in the United States) or advisory guidelines suggested by bodies such as the World Health Organization (WHO). [3]

  8. National Ambient Air Quality Standards - Wikipedia

    en.wikipedia.org/wiki/National_Ambient_Air...

    9 ppm (10 mg/m 3) 8-hour Not to be exceeded more than once per year 40 CFR 50.8: Ozone (O 3) Primary and Secondary 0.12 ppm (235 μg/m 3) 1-hour a: expected number of days per calendar year, with maximum hourly average concentration greater than 0.12 ppm, is equal to or less than 1 40 CFR 50.9: Primary and Secondary 0.070 ppm (140 μg/m 3) 8-hour

  9. World Reference Base for Soil Resources - Wikipedia

    en.wikipedia.org/wiki/World_Reference_Base_for...

    The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. [ 1 ]