Evaporation ponds are artificial

pond A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...

s with very large surface areas that are designed to efficiently

evaporate Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when hum ...

water by

sunlight Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrare ...

and expose water to the ambient temperatures. Evaporation ponds are inexpensive to design making them ideal for multiple purposes such as

wastewater treatment Wastewater treatment is a process which removes and eliminates contaminants from wastewater. It thus converts it into an effluent that can be returned to the water cycle. Once back in the water cycle, the effluent creates an acceptable impact on ...

processes, storage, and extraction of minerals. Evaporation ponds differ in purpose and may result in a wide range of environmental and

health Health has a variety of definitions, which have been used for different purposes over time. In general, it refers to physical and emotional well-being, especially that associated with normal functioning of the human body, absent of disease, p ...

effects.

Uses

Extraction

Salt evaporation pond A salt evaporation pond is a shallow artificial salt pan designed to extract salts from sea water or other brines. The salt pans are shallow and expansive, allowing sunlight to penetrate and reach the seawater. Natural salt pans are formed thr ...

s produce

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

from

seawater Seawater, or sea water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximat ...

. Evaporation ponds are used to extract

lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...

from underground brine solution. The extracted Lithium is then used to make ion batteries. Mines use them to separate

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

from water. The ore can be sold for use in different industries. Potash evaporation ponds are used to extract

potassium Potassium is a chemical element; it has Symbol (chemistry), symbol K (from Neo-Latin ) and atomic number19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to ...

from the mineral rich solution. The potassium extracted is used for products like

fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...

Storage

Evaporation ponds are also used to dispose of

brine Brine (or briny water) is a high-concentration solution of salt (typically sodium chloride or calcium chloride) in water. In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawat ...

from

desalination Desalination is a process that removes mineral components from saline water. More generally, desalination is the removal of salts and minerals from a substance. One example is Soil salinity control, soil desalination. This is important for agric ...

plants. Evaporation ponds at contaminated sites remove the water from

hazardous waste Hazardous waste is waste that must be handled properly to avoid damaging human health or the environment. Waste can be hazardous because it is Toxicity, toxic, Chemical reaction, reacts violently with other chemicals, or is Corrosion, corrosive, ...

, which reduces its weight and volume and allows it to be more easily transported and stored. Evaporation ponds are used to prevent run off agricultural wastewater contaminants like

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s and

s from entering bodies of water they would normally flow into.

Design and operation

Location of the evaporation pond should be considered for optimal results. Evaporation will be higher in places with high amounts of

solar radiation Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible light perceptible to the human eye as well as invisible infrared (typically p ...

, high temperatures, and low

wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...

levels. Since evaporation ponds operate best with greater surface area of evaporation, large amount of land is required, so low quality, low cost land is betterA shallow pond covering greater surface area will result in faster rates of evaporation. An evaporation pond has

shallow Shallow may refer to: Places * Shallow (underwater relief), where the depth of the water is low compared to its surroundings * Shallow Bay (disambiguation), various places * Shallow Brook, New Jersey, United States * Shallow Inlet, Victoria ...

depths and, to prevent

contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that renders something unsuitable, unfit or harmful for the physical body, natural environment, workplace, etc. Types of contamination Within the scien ...

of the environment from its content, a range of pond liners are used, categorized as

geomembrane A geomembrane is very low permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (liquid or gas) migration in a human-made project, structure, or system. Geomembranes are m ...

, constructed

bentonite Bentonite ( ) is an Absorption (chemistry), absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelli ...

clay, or natural

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...

. Each pond liner is prone to leakage and requires regular maintenance. The contents of the evaporation pond depend on the use, the evaporation pond will contain

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

and the desired contents hoping to be extracted. The desired contents range from

waste Waste are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic value. A wast ...

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): M ...

, and the remaining contents are either stored or extracted.

Health impacts

Evaporation ponds, when not maintained, may leak contaminated contents into the environment which directly effect human and animal health. The contents within the evaporation pond can be found to contaminate surrounding soil and surrounding water sources. Contaminated water can contain sources of chemicals and hard metals like

selenium Selenium is a chemical element; it has symbol (chemistry), symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elem ...

which in accumulation can be

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

when ingested by humans or animals. Employees working directly with the evaporation ponds may experience acute health conditions like dry skin and

irritation Irritation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant. Irritants are typically thought of as chemical age ...

from close contact of contents within the pond.

Environmental impacts

Evaporation ponds pose a threat to

environmental sustainability Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...

because resources like water, land, and minerals are rapidly used at large scales. These resources are limited in nature. An increasing demand for extracted products and treated wastewater will result in evaporation ponds expanding and related issues worsening until the depletion of these resources. Evaporation ponds are found to increase

green house gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

emissions and therefore contribute to environmental issues like warming of the planet and

ocean acidification Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ...

. As the pond evaporates, it carries with it volatile pollutants into the air.

Technology

Advancing technology has made evaporation pond design and implementation more effective. With new resources such as fabric evaporations for salt-tolerant plants, the ponds' costs and environmental impacts can be mediated.

References

California Department of Water Resources - Evaporation Ponds
* ttp://www.ars.usda.gov/is/pr/2005/050912.htm USDA - Turning Evaporation Ponds into Arable Landbr>World Bank - AgWater Sourcebook
* * * {{pond Ponds Resource extraction Waste treatment technology