Glossary of Environmental Science - M

M

• magma - molten rock that sometimes forms beneath the surface of the Earth (or any other terrestrial planet) that often collects in a magma chamber and is ejected by volcano's.
• manure - organic matter used as fertilizer in agriculture.
• market benefits - benefits of a climate policy that can be measured in terms of avoided market impacts such as changes in resource productivity (e.g., lower agricultural yields, scarcer water resources) and damages to human-built environment (e.g., coastal flooding due to sea-level rise).
• material flow – the cycling of materials, which is driven by the flow of energy.
• material identification - words, numbers or symbols used to designate composition of components of a product or packaging. Note: a material identification symbol does not indicate whether an item can be recycled.
• materials recovery facility (MRF) - a centre for the reception and transfer of materials recovered from the waste stream. At a MRF, materials are also sorted by type and treated (e.g. cleaned, compressed)
• Mauna Loa record - the record of measurement of atmospheric CO₂ concentrations taken at Mauna Loa Observatory, Mauna Loa, Hawaii, since March 1958. This record shows the continuing increase in average annual atmospheric CO₂ concentrations.
• maximum soil water deficit – amount of water stored in the soil that is readily available to plants
• megadiverse countries – The 17 countries that are home to the largest fraction of wild species (Australia is one such)
• microorganism – an organism visible only through a microscope.
• middle East– 15 countries - Bahrain, Islamic Rep. Iran, Iraq, Israel, Jordan, Kuwait, Lebanon, Oman, Qatar, Saudi Arabia, Syria, United Arab Emirates, Yemen.
• mobile garbage bin - A wheeled kerbside container for the collection of garbage or other materials.
• monoculture - the practice of producing or growing one single crop over a wide area.
• mortality rate – generally understood as the total number of deaths per 1000 people of a given age group
• mulch - any composted or non-composted organic material, excluding plastic, that is suitable for placing on soil surfaces to restrict moisture loss from the soil and to provide a source of nutrients to the soil.
• municipal waste - solid waste generated from domestic premises (garbage and hard waste) and council activities such as street sweeping, litter and street tree lopping. Also includes waste dropped at transfer stations and construction waste from owner/occupier renovations.