Water quality indicators

upright=1|thumb|right|Test tubes containing solutions of pH 1–10 colored with Universal indicator|an indicator

Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble (inorganic) nitrate is bismuth oxynitrate.

thumb|upright=1.3|right|Annual mean sea surface salinity for the World Ocean. Data from the [[World Ocean Atlas 2009.]] thumb|upright|right|International Association for the Physical Sciences of the Oceans (IAPSO) standard seawater. Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal to ‰).

chemical, physical, biological, and radiological characteristics of water

thumb|Caddisfly (order Trichoptera), a [[macroinvertebrate used as an indicator of water quality.]] A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other small water crustaceans that are present in many water bodies can be monitored for changes (biochemical, physiological, or behavioural) that may indicate a problem within their ecosystem. Bioindicators can tell us about the cumulative effects of different

oxygen needed to remove organics from water

measure of the amount of oxygen that can be consumed by reactions in a solution

thumb|Turbidity standards of 5, 50, and 500 NTU

water that has a high mineral content

intervals in the Earth's past

measurement in environmental chemistry

thumb|right|200px|Sea surface alkalinity (from the Global Ocean Data Analysis Project|GLODAP [[climatology).]]

group of bacterial species

low environmental oxygen levels

thumb|300px|Lake Erie in October 2011, during an intense cyanobacteria bloom

water color in different conditions

relative measure of the amount of oxygen that is dissolved or carried in a given medium

concentration of organic carbon in a sample

bloom of algae that causes harm to the nearby ecosystem

water chemistry parameter influencing dissolved oxygen concentration

measure of the ability of a solution containing electrolytes to conduct electricity

Bacterium

water quality measurement

test to determine concentration of dissolved oxygen in water

Euxinia or euxinic conditions occur when water is both anoxic and sulfidic. This means that there is no oxygen (O2) and a raised level of free hydrogen sulfide (H2S). Euxinic bodies of water are frequently strongly stratified; have an oxic, highly productive, thin surface layer; and have anoxic, sulfidic bottom water. The word "euxinia" is derived from the Greek name for the Black Sea (Εὔξεινος Πόντος (Euxeinos Pontos)) which translates to "hospitable sea". Euxinic deep water is a key component of the Canfield ocean, a model of oceans during part of the Proterozoic eon (a part specifically kno

Water purity rating based on fecal bacteria content