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Vertisols of the world A more detailed map of the global distribution of Vertisols. A vertisol is a Soil Order in the USDA soil taxonomy [1] and a Reference Soil Group in the World Reference Base for Soil Resources (WRB). [2] It is also defined in many other soil classification systems. In the Australian Soil Classification it is called ...
Expansive clay, also called expansive soil, is a clay soil prone to large volume changes (swelling and shrinking) directly related to changes in water content. [1] Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called vertisols.
Soils with this shrink-swell capacity fall under the soil order of Vertisols. [6] As these soils dry, deep cracks can form on the surface, which then allows water to penetrate to deeper levels of the soil. [7] This can cause the swelling of these soils to become cyclical, with periods of both shrinking and swelling.
Some of the UNECE's water related problems are of water quantity and water quality, high water stress and overexploitation of water resources, increasing droughts and floods, contaminated water resulting in water-related diseases, etc. These issues are even harder to solve due to transboundary nature of the water sources in the UNECE region.
Water pollution is the contamination of natural water bodies by chemical, physical, radioactive or pathogenic microbial substances. [2] Point sources of water pollution are described by the CWA as "any discernible, confined, and discrete conveyance from which pollutants are or may be discharged."
Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. [1] Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. [2]
Operators must use the BAT to control pollution from their industrial activities to prevent, and where that is not practicable, to reduce to acceptable levels, pollution to air, land and water from industrial activities. The Best Available Techniques also aim to balance the cost to the operator against benefits to the environment.
Histosols are generally very difficult to cultivate because of the poor drainage and often low chemical fertility. However, Histosols formed on very recent glacial lands can often be very productive when drained and produce high-grade pasture for dairying or beef cattle.