Water (resources and pollution)

Residence time

the length of time water typically stays in a compartment

River discharge

a measure of the amount of water passing a fixed point in a given amount of time

Major role of the atmosphere

redistribute water over landmasses

Water pollutants

anything that degrades water quality

River’s fresh water comes from

precipitation, groundwater, snowmelt

Important wetland characteristics for humans

help slow waters, decreasing flooding and erosion severity; plant growth stabilizes soil; hold back surface runoff

Air currents

carriers of pollution in atmospheric deposition of a contaminant

Oligotrophic waters

have little nutrition; characteristics

Eutrophic waters

good; well-nourished; organic and organism rich

Eutrophication

natural sedimentation and nutrient influx from streams; anthropogenic

Inorganic pollutants

acids, salts, metals

Sediment pollution

largest source; responsible for widespread problems

Sources of inorganic chemicals

weathered rocks; mining/processing/using/discarding minerals

Organic pollutants

plastics, pesticides, drugs

Problems of excess sediment in water

obstructing shipping channels, fills in lakes and reservoirs, increases cost of water purification

Power plant cooling water

largest single industrial use; 50-75% of industrial withdrawal

Developed vs developing country water usage

developed countries use roughly 10x more than developing nations; poorer countries can’t afford infrastructure to obtain/deliver water

Water scarcity

lack of sufficient available water resources to meet regional demands; due to lack of natural resources or poor economic management

Factor determining water rich/poor

renewable water supplies

Countries without adequate water supplies

roughly ⅓ of global population

Droughts

extended period of consistently below average participation; often cyclic

1930s Dust Bowl

worst in US to that point; poor soil conservation made it bad; loss of topsoil

Point sources

discharge pollution from specific locations (drain pipes, ditches, sewer outfalls); easy to find, monitor and regulate

Non-point sources

no specific location where they discharge into a particular body of water (runoff); hard to identify

Inorganic chemical water pollutants

heavy metals are greatest concern; toxic in minute concentrations; highly persistent (bioaccumulation); mercury is most widespread contaminant

Permafrost

beneath active layer; soil frozen in place for at least 2 years; stores mercury

Mercury deposited from atmosphere

bounds to organics; microbial decay releases mercury; decay ceases when frozen

Main sources of organic chemical water pollutants

improper disposal of industrial and household wastes; pesticide and herbicide runoff

Pathogens as biological water pollutants

disease-causing organisms; most serious pollutants for human health

Organic waste as biological water pollutants

increases oxygen consumption; oxygen removed by respiration and chemical processes; quantify with biochemical oxygen demand

Oxygen sag

downstream of point source (sewage outflow); long times and distances to recover

Marine eutrophication

partially enclosed seas are susceptible; urban and agriculture effluents often dumped untreated into the sea (creates dead zones); supports blooms of deadly aquatic microorganisms (such as toxic algae)

Rivers and sediments

rivers naturally carry sediment; fertilizes floodplains, creates deltas; increased by farming and urbanization

Thermal pollution

heat from cooling effluent (power plants/ other industries)

Microbeads

tiny plastic beads; allowed for industrial uses; banned from personal care products

Microfibers

shed from synthetic clothing; smaller than microbeads and maybe more pervasive

Microplastics

wastewater treatment can’t remove; don’t biodegrade; widespread globally

1972 water pollution control act/“clean water act”

goal to make USA waters swimmable and fishable; national pollution discharge elimination system; must disclose what is being dumped

1974 safe drinking water act

goal to set maximum allowable levels of pollutants in drinking water; control what comes out of lakes, rivers, etc

Ozone depletion/hole

reduction over antarctica in southern hemisphere winter; found in 1985

Source of ozone depletion

chlorine-based aerosols; inert (didn’t chemically react); synthetic compounds (use began in 1930s and grew from there); exceptionally cold winters cause high-altitude ice crystals to form and absorb ozone and CFCs; sunlight during spring breaks apart CFCs and chlorine ions pull an oxygen from ozone

Distribution of water

96.5% oceans, 68.7% snow and ice, ground water 30%, lakes 20%