Glossary of Terms

Here are some scientific terms you will encounter in this issue's stories. Definitions adapted from Wikipedia unless otherwise noted.

Aquifer: An underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well.

Cover crop: A crop planted primarily to manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity, and wildlife in an agroecosystem.

Enteric: Of, relating to, or affecting the human gastrointestinal tract.

Fracking: The injection of fluid into shale beds at high pressure in order to free up petroleum resources such as oil or natural gas. Definition adapted from Merriam-Webster.

Green infrastructure: A network for solving urban and climatic challenges by building with nature. The main components of this approach include stormwater management, climate adaptation, less heat stress, more biodiversity, food production, better air quality, sustainable energy production, clean water, and healthy soils.

Groundwater: The water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. See also surface water.

Headwaters: The furthest place in a river or stream from its estuary (brackish transition zone between the river environment and the open sea) or confluence (meeting) with another river, as measured along the course of the river.

Hydrogeology: The area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aquifers).

Hydrology: The scientific study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources, and environmental watershed sustainability.

Nutrient pollution: A form of water pollution referring to contamination by excessive inputs of nutrients, usually nitrogen or phosphorus, that stimulate algal growth. Sources of nutrient pollution include surface runoff from farm fields and pastures, discharges from septic tanks and feedlots, and emissions from combustion.

Pathogen: In the oldest and broadest sense, anything that can produce disease. Typically the term is used to describe an infectious agent such as a virus, bacterium, prion, fungus, or even another micro-organism.

Point/nonpoint source: A point source of pollution is a single identifiable source of air, water, thermal, noise or light pollution (such as a smokestack or wastewater treatment plant). Non-point source pollution affects a water body from sources such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Although these pollutants have originated from a point source, the long-range transport ability and multiple sources make them a non-point source of pollution.

Potable water: Water that is safe to drink or to use for food preparation.

Recharge: Groundwater recharge is a hydrologic process where water moves (i.e., is restored) to groundwater. Surface water recharge is a hydrologic process where water runs off to surface watercourses.

Riparian zone: The interface between land and a river or stream.

Rotavirus: The most common cause of diarrhoeal disease among infants and young children. Nearly every child in the world is infected with rotavirus at least once by the age of five. Immunity develops with each infection, so subsequent infections are less severe; adults are rarely affected.

Sediment: Any naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice, and/or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea be deposited by sedimentation and may eventually become sandstone and siltstone (sedimentary rocks).

Surface water: Surface water is water on the surface of the planet such as in a river, lake, wetland, or ocean. It can be contrasted with groundwater and atmospheric water.

Tile drainage: In agriculture, a type of drainage system that removes excess water from soil below the surface. Whereas irrigation is the practice of adding additional water when the soil is naturally too dry, tile drainage brings soil moisture levels down for optimal crop growth. Too much subsurface water can prevent root development and inhibit the growth of crops. Too much water also can limit access to the land, particularly by farm machinery.

Tillage: The agricultural preparation of soil for growing crops by mechanical agitation of various types, such as digging, stirring, and overturning.

Trophic: Describing the relationships between the feeding habits of organisms in a food chain.

Vernal pond: A temporary pool of water that provides habitat for distinctive plants and animals. Such ponds are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe development of natal amphibian and insect species unable to withstand competition or predation by fish.

Watershed: Drainage divide; the line that separates neighboring drainage basins (areas of land where surface water converges).

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