• Eutrophication• Tsunami• Salt water intrusion• Quicksand• Waterspout

Arcelie P. Maata

Eutrophication• An enrichment by or excess of nutrients

to the water. and may result in an explosive growth of algae.

• is the ecosystem response to the addition of artificial or natural substances, mainly phosphates, through detergents, fertilizers, or sewage, to an aquatic system.

• Eutrophication was recognized as a water pollution problem in European and North American lakes and reservoirs in the mid-20th century.

Since then, it has become more widespread. Surveys showed that 54% of lakes in Asia are eutrophic; in Europe, 53%; in North America, 48%; in South America, 41%; and in Africa, 28%.

Cause of Eutrophication

• Domestic wastewater• Industrial waste• Agriculture (fertilizer

use)Atmospheric deposition of nitrogen (livestock and gases)

Effects of Eutropication• Increasing biomass of phytoplankton resulting in

'algal blooms'.• Hypoxia (reduced dissolved oxygen content of a

body of water).• An increasing number of incidents of fish kills.• The water can have a bad taste, color and odor

which has a negative impact on tourism. Governments have to invest more in waste water treatment.

• Decline or loss of species biodiversity (commercially important species may disappear).

• Some phytoplankton species produce toxins that cause severe symptoms such as diarrhea, memory loss, paralysis and in severe causes death.

• Changes in macrophyte species composition and biomass

• Decreases in water transparency (increased turbidity)

• Colour, smell, and water treatment problems • Dissolved oxygen depletion • Loss of desirable fish species • Reductions in harvestable fish and shellfish • Decreases in perceived aesthetic value of the water

body

• Sodium triphosphate, once a component of many detergents, was a major contributor to eutrophication.

Natural Eutrophication• Although eutrophication is commonly caused by

human activities, it can also be a natural process, particularly in lakes. Eutrophy occurs in many lakes in temperate grasslands, for instance. Paleolimnologists now recognize that climate change, geology, and other external influences are critical in regulating the natural productivity of lakes. Some lakes also demonstrate the reverse process (meiotrophication), becoming less nutrient rich with time. The main difference between natural and anthropogenic eutrophication is that the natural process is very slow, occurring on geological time scales.

Ocean waters eutrophication • Eutrophication is a common phenomenon in

coastal waters. In contrast to freshwater systems, nitrogen is more commonly the key limiting nutrient of marine waters; thus, nitrogen levels have greater importance to understanding eutrophication problems in salt water. Estuaries tend to be naturally eutrophic because land-derived nutrients are concentrated where run-off enters a confined channel. Upwelling in coastal systems also promotes increased productivity by conveying deep, nutrient-rich waters to the surface, where the nutrients can be assimilated by algae.

Terrestrial ecosystems eutrophication • Terrestrial ecosystems are subject to similarly adverse

impacts from eutrophication. Increased nitrates in soil are frequently undesirable for plants. Many terrestrial plant species are endangered as a result of soil eutrophication, such as the majority of orchid species in Europe. Meadows, forests, and bogs are characterized by low nutrient content and slowly growing species adapted to those levels, so they can be overgrown by faster growing and more competitive species. In meadows, tall grasses that can take advantage of higher nitrogen levels may change the area so that natural species may be lost. Species-rich fens can be overtaken by reed or reedgrass species. Forest undergrowth affected by run-off from a nearby fertilized field can be turned into a nettle and bramble thicket.

ecological impacts

• decreased biodiversity • changes in species composition and

dominance• toxicity effects.

• Eutrophication is apparent as increased turbidity in the northern part of the Caspian Sea, imaged from orbit

The eutrophication of the Potomac River

evident from the bright green water, caused by a dense bloom of cyanobacteria.

Eutrophication in a canal

Green algae on the beach (Nord Finistère, Brittany-France)

Tsunami• is a series of ocean waves caused by an

underwater earthquake, landslide, or volcanic eruption. More rarely, a tsunami can be generated by a giant meteor impact with the ocean. These waves can reach heights of over 100 ft.

• A tsunami is a series of ocean waves with very long wavelengths (typically hundreds of kilometres) caused by large-scale disturbances of the ocean

Causes of Tsunami

• earthquakes• landslide• volcanic eruptions• explosions • meteorites

How are tsunamis measured or observed?

• In the deep ocean, a tsunami has a small amplitude (less than 1 metre) but very long wavelength (hundreds of kilometres). This means that the slope, or steepness of the wave is very small, so it is practically undetectable to the human eye. However, there are ocean observing instruments that are able to detect tsunamis.

facts About Tsunamis• If caught by a tsunami wave, it is better not to

swim, but rather to grab a floating object and allow the current to carry you.

• Tsunamis retain their energy, meaning they can travel across entire oceans with limited energy loss.

• Tsunami means “harbor wave” in Japanese (tsu = harbor + nami = wave), reflecting Japan’s tsunami-prone history.

• Tsunamis can travel at speeds of about 500 miles or 805 kilometers an hour, almost as fast as a jet plane.

• Hawaii is always at great risk for a tsunami – they get about 1 per year and a severe one every 7 years. The biggest tsunami that occurred Hawaii happened in 1946, the coast of Hilo Island was hit with 30 ft waves at 500 mph.

• In 2004, the Indian Ocean tsunami was caused by an earthquake with the energy of 23,000 atomic bombs. After the earthquake, killer waves radiating from the epicenter slammed into the coastline of 11 countries. The final death toll was 283,000.

• The first wave of a tsunami is usually not the strongest, successive waves get bigger and stronger.

• Scientists can accurately estimate the time when a tsunami will arrive almost anywhere around the world based on calculations using the depth of the water, distances from one place to another, and the time that the earthquake or other event occurred.

• The states in the U.S. at greatest risk for tsunamis are Hawaii, Alaska, Washington, Oregon, and California.

Earthquakes under the ocean can cause giant waves called tsunamis. Here, a tsunami heads toward shore after a small earthquake off the coast of Indonesia.

Salt water intrusion

• Salt water intrusion occurs in coastal freshwater aquifers when the different densities of both the saltwater and freshwater allow the ocean water to intrude into the freshwater aquifer.

• Saltwater intrusion is the movement of saline water into freshwater aquifers, which can lead to contamination of drinking water sources and other consequences.

When groundwater levels in aquifers are depleted faster than they can recharge. This is directly related to the position of the interface and determines the amount of saltwater that can intrude into the freshwater aquifer system. Since saltwater intrusion is directly related to the recharge rate of the groundwater, this allows for other factors that may contribute to the encroachment of seawater into the freshwater aquifers. Climatic variables, such as precipitation, surface runoff, and temperature can play a big role in affecting saltwater intrusion.

What causes saltwater intrusion?

With lower precipitation amounts and warmer temperatures, the recharge rate will be much less due to lack of groundwater present and increased evaporation. other factors may influence the groundwater recharge rate indirectly. An example of this would be the rising carbon dioxide emissions in the atmosphere. Increasing carbon dioxide levels can lead directly to an increase in average surface temperatures, indirectly increasing the evaporation rate and affecting the recharge of freshwater into the coastal aquifers.

Effect on water supply• Many coastal communities around the United

States are experiencing saltwater contamination of water supply wells, and this problem has been seen for decades. The consequences of saltwater intrusion for supply wells vary widely, depending on extent of the intrusion, the intended use of the water, and whether the salinity exceeds standards for the intended use. In some areas such as Washington State, intrusion only reaches portions of the aquifer, affecting only certain water supply wells. Other aquifers have faced more widespread salinity contamination, significantly affecting groundwater supplies for the region.

Catfish Point control structure

(lock) on the Mermentau River

in coastal Louisiana

• Saltwater is also an issue where a lock separates saltwater from freshwater (for example the Hiram M. Chittenden Locks in Washington). In this case a collection basin was built from which the saltwater can be pumped back to the sea. Some of the intruding saltwater is also pumped to the fish ladder to make it more attractive to migrating fish.

Water Ways (St. Johns River Water Management District, 2008)

Quicksand

• Quicksand is a colloid hydrogel consisting of fine granular material (such as sand or silt), clay, and water.

• Quicksand forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it creates a liquefied soil that loses strength and cannot support weight.

Quicksand can form in standing water or in upwards flowing water (as from an artesian spring). In the case of upwards flowing water, seepage forces oppose the force of gravity and suspend the soil particles.

Quicksand may be found inland (on riverbanks, near lakes, or in marshes), or near the coast.

The saturated sediment may appear quite solid until a sudden change in pressure or shock initiates liquefaction. This causes the sand to form a suspension and lose strength. The cushioning of water gives quicksand, and other liquefied sediments, a spongy, fluidlike texture. Objects in liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced soil/water mix and the submerged object floats due to its buoyancy.

Liquefaction is a special case of quicksand. In this case, sudden earthquake forces immediately increase the pore pressure of shallow groundwater. The saturated liquefied soil loses strength, causing buildings or other objects on that surface to sink or fall.To move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefy it. The forces required to do this are quite large: to remove a foot from quicksand at a speed of .01 m/s would require the same amount of force as "that needed to lift a medium-sized car."

Properties• Quicksand is a shear thinning

non-Newtonian fluid: when undisturbed, it often appears to be solid ("gel" form), but a minor (less than 1%) change in the stress on the quicksand will cause a sudden decrease in its viscosity. After an initial disturbance—such as a person attempting to walk on it—the water and sand in the quicksand separate and dense regions of sand sediment form; it is because of the formation of these high volume fraction regions that the viscosity of the quicksand seems to decrease suddenly. Someone stepping on it will start to sink.

Quicksand itself is harmless; a human or animal is unlikely to sink entirely into quicksand due to the higher density of the fluid (assuming the quicksand is on dry ground and not under water). Continued or panicked movement may cause the victim to sink deeper, leading to belief that quicksand is dangerous. Because it increasingly impairs human locomotion, it allows harsher elements such as sunlight, dehydration, carnivores, omnivores, hypothermia or tides to harm a trapped person.

Quicksand may be escaped by slow movement of the legs in order to reduce viscosity of the fluid, and rotation of the body so as to float in the supine position.

waterspout

• A waterspout is a whirling column of air and water mist

• A waterspout is an intense columnar vortex (usually appearing as a funnel-shaped cloud) that occurs over a body of water. They are connected to a towering cumuliform cloud or a cumulonimbus cloud.In the common form, it is a non-supercell tornado over water.

Waterspouts fall into two categories

Tornadic waterspouts.• tornadic waterspouts develop downward in a

thunderstorm.• Tornadic waterspouts are tornadoes that form

over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.

Tornadic waterspout on 15 July 2005 off the coast of Punta Gorda, Florida, caused by a severe thunderstorm.

fair weather waterspouts• Fair weather waterspouts usually form along

the dark flat base of a line of developing cumulus clouds. This type of waterspout is generally not associated with thunderstorms.

• a fair weather waterspout develops on the surface of the water and works its way upward. By the time the funnel is visible, a fair weather waterspout is near maturity.

• Fair weather waterspouts form in light wind conditions so they normally move very little.

Non-tornadic waterspouts seen from the beach at Kijkduin near The Hague, the Netherlands on 27 August 2006.

Waterspouts have a five-part life cycle:

•formation of a dark spot on the water surface.•spiral pattern on the water surface.•formation of a spray ring.•development of the visible condensation funnel.•ultimately decay.

A family of four waterspouts seen on the Great Lakes (Lake Huron) on 9 September 1999.

Four waterspouts seen in the Florida Keys on 5 June 2009.

If a waterspout moves onshore, the National Weather Service issues a tornado warning, as some of them can cause significant damage and injuries to people. Typically, fair weather waterspouts dissipate rapidly when they make landfall, and rarely penetrate far inland.

According to NOAA's National Weather Service, the best way to avoid a waterspout is to move at a 90-degree angle to its apparent movement. Never move closer to investigate a waterspout. Some can be just as dangerous as tornadoes.

THANK YOU for listening !!

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