蓝水、绿水和灰水

Blue water

The blue water footprint is the volume of water that has been sourced from surface or groundwater resources (lakes, rivers, wetlands and aquifers) and has either evaporated (for example while irrigating crops), or been incorporated into a product or taken from one body of water and returned to another, or returned at a different time. Irrigated agriculture, industry and domestic water use can each have a blue water footprint.[9]

Green water

The green water footprint is the amount of water from precipitation that, after having been stored in the root zone of the soil (green water), is either lost by evapotranspiration or incorporated by plants. It is particularly relevant for agricultural, horticultural and forestry products.[9]

Grey water

The grey water footprint is the volume of water that is required to dilute pollutants (industrial discharges, seepage from tailing ponds at mining operations, untreated municipal wastewater, or nonpoint source pollution such as agricultural runoff or urban runoff) to such an extent that the quality of the water meets agreed water quality standards.[9] It is calculated as:{\displaystyle {\frac {L}{c_{\text{max}}-c_{\text{nat}}}}}

{\displaystyle {\frac {L}{c_{\text{max}}-c_{\text{nat}}}}}

where L is the pollutant load (as mass flux), cmax the maximum allowable concentration and cnat the natural concentration of the pollutant in the receiving water body (both expressed in mass/volume).[10]

Reference: https://en.wikipedia.org/wiki/Water_footprint#Blue_water_footprint

Updated: 2019-07-25 — am8:48

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