How Sinkholes Develop?... With Chemical Equation

How Sinkholes Develop?... With Chemical Equation

•Naturally occurring sinkholes are most commonly found in a type of terrain known as karst topography, which consists of bedrock (rock beneath the soil) filled with nooks and crannies. The underlying bedrock in karst landscapes is usually made of limestone. A great portion of the state of Florida is, in essence, sitting atop one continuous slab of limestone, making it vulnerable to sinkholes. Limestone is composed of calcium carbonate (CaCO3), which primarily comes from the remnants of corals and other types of marine organisms, whose shells are made of calcium carbonate.

•Sinkholes often form when acidic groundwater or acid rain dissolves limestone, a porous 9-rock present in the soil, creating voids and cavities. The soil resting on top of the limestone then sinks or collapses, causing a sinkhole.

•Limestone builds up slowly after these animals die and their shells are deposited and accumulate over time. Other substances composed of calcium carbonate include marble, chalk, Tums antacid tablets, and eggshells. To understand how limestone bedrock contributes to sinkholes, consider what happens when you place an egg in a glass of vinegar, which contains 5% acetic acid (CH3COOH). You will notice that little bubbles of carbon dioxide gas form almost immediately and, within a day or two, the eggshell will have completely disappeared, leaving you with the egg’s translucent membrane to protect the egg. The eggshell, which is composed of calcium carbonate, does not normally dissolve in water, but in the presence of acetic acid, calcium carbonate and acetic acid react with each other, causing the eggshell to dissolve according to the following chemical reaction:

•2 CH3COOH (aq) + CaCO3 (s) Acetic acid + Calcium carbonate
•➞ [Ca2+ (aq) + 2CH3COO– (aq)] + H2O (l)
•➞ Calcium acetate + Water + CO2 (g) + Carbon dioxide

•Any substance made of calcium carbonate will react with an acid. Limestone, being made of calcium carbonate, will react with an acid and will be slowly worn away. But are there acids underground?

•To answer this question, consider what happens to rainfall (which eventually 9-becomes groundwater) as it passes through the atmosphere. While falling through the air, the rain comes into contact with carbon dioxide. Although carbon dioxide comprises only about 0.04% of the atmosphere, that is enough to make rainfall acidic, lowering its Ph to about 5.6. So, by the time rainfall reaches the ground, it has turned into acid. The reaction is as follows:

•H2O (l) + CO2 (g) ➞ H2CO3 (aq)
•Water + Carbon dioxide ➞ Carbonic acid
•Carbonic acid then dissociates to give a hydrogen ion (H+) and a bicarbonate ion (HCO3 –):

•H2CO3 (aq) ➞ H+ (aq) + HCO3 – (aq)

•The ability of carbonic acid to dissociate by producing hydrogen ions is what makes this molecule an acid. Over time, acidic rainwater seeps into the ground and comes into contact with limestone bedrock. Water makes its way into cracks or pockets in the rock, reacting with the limestone and eventually making holes and fissures in the rock. Sinkholes occur when acidic rainwater has eaten away so much of the underlying limestone bedrock beneath the soil that the ground collapses.

•The more it rains, the greater the amount of carbonic acid leaching into the soil below.

•Humid areas have the most rainfall. High humidity in the air leads to cloud formation, which eventually produces rainfall. So it is no surprise that Florida leads the United States in the number of sinkholes because it has both limestone bedrock and high humidity.


•The acidity of rainwater is not the only reason water in the ground is acidic. Decaying organic materials and root respiration also produce carbon dioxide, which dissolves in soil water to form carbonic acid.

Land subsidence

Land subsidence

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials.

Causes of  Subsidence 

Subsidence is caused by a diverse set of human activities and natural processes, including :-
1.mining of coal , metallic ores,
2.Limestone , salt, and sulfur; withdrawal of groundwater, petroleum, and geothermal fluids;
3.dewatering of organic soils;
4.pumping of groundwater from limestone;
5.wetting of dry, low-density deposits, which is known as hydro compaction; natural sediment compaction;
6.melting of permafrost; liquefaction; and crustal deformation

Catastrophic Subsidence as Result For Water Level Decline (Sinkholes).

•Water is stored in underlying carbonate rocks and moves through interconnected openings along bedding planes, joints, fractures, and faults, some of which are enlarged by solutioning.
•Recharge from precipitation, in response to gravity, moves downward into this system of openings or toward the stream channel, where it discharges and becomes streamflow

•Sinkholes can be separated into categories described as“induced” and “natural.” Induced sinkholes are those caused or accelerated by human activities, whereas natural ones occur in nature. Sinkholes resulting from water level declines

Induced sinkholes

•Induced sinkholes (catastrophic subsidence) are those caused, or accelerated, by human water development/management activities
•activities. These sinkholes commonly result from a water level decline due to pumpage.
•Are most predictable in a youthful karst area impacted by groundwater withdrawals.

Triggering mechanisms resulting from water level declines

(1)loss of buoyant support of the water
(2)increased gradient and water velocity
(3)water-level fluctuations

Effects of Groundwater Contamination

Effects of Groundwater Contamination

Understanding the common sources of groundwater pollution is always a good first step, but from there, you should realize what the effects on your health and the world around you can potentially be when this type of contamination is present. Now that you can recognize what are possible sources of groundwater contamination, read on to find out more about what this means for you and your community.

1-Health

Health effects are some of the greatest risks associated with groundwater pollution. Here are just a few you should be concerned with.

Hepatitis. In areas where septic systems have not been installed or kept up correctly, groundwater may become infected with hepatitis due to human waste present in the water supply. Hepatitis is a very serious condition that causes irreversible damage to the liver.

Dysentery. Much like hepatitis, dysentery can be caused by drinking water where waste is present—either human or animal in nature. Once again, when septic systems don’t operate correctly, the chance for dysentery is much higher, much like with hepatitis. Dysentery causes infection throughout the intestine and digestive system, and can also cause diarrhea so severe it can lead to dehydration and even death when not treated properly.

Poisoning. When wells are not dug or placed correctly, poisons from both nature and from human use of pesticides and solvents can leach into the well water and poison the water supply. When humans then drink this water, they can become very ill very fast from exposure to chemicals and other pollutants that are unsafe for ingestion. This can also make animals sick as well, including animals that might be watered from a well on a farm.

2-Economy

When groundwater becomes contaminated, the economy can also easily suffer. Check out this list of potential economic problems associated with groundwater pollution.

Depreciating value of land. When groundwater becomes more contaminated in a given area, that area becomes less capable of sustaining human, animal, and plant life. If the area is known for its natural beauty and that nature begins to suffer the effects of pollution, the chances of people wanting to live there decrease even more. Although it might not be an immediate result of groundwater pollution, the depreciation of land value is definitely a potential side effect.

Less stable industry. Many industries rely on groundwater to help produce their products and keep their factories running smoothly. Since the pH and quality of groundwater from a given area rarely changes, it becomes a vital part of many industries that rely on water they don’t have to constantly test. However, when groundwater becomes polluted, this convenience is stripped away, and the industries are less capable of stable production. This, in turn, can affect the economy in any given area as industries are forced to move.

3-Environment

Last but certainly not least, the environment can be seriously altered when groundwater is polluted. Here are just some of the ways in which this occurs.

Nutrient pollution. Groundwater pollution can cause certain types of nutrients that are necessary in small amounts to become far too abundant to sustain normal life in a given ecosystem. Fish might start dying off quickly because they are no longer able to process the water in their water supplies, and other animals might become sick from too much of certain types of nutrients in the water they drink. Plants might not be able to absorb water as easily, and the entire ecosystem will suffer

Toxic water in ecosystems. When groundwater that supplies lakes, rivers, streams, ponds, and swamps becomes contaminated, this slowly leads to more and more contamination of the surface water as well. When this happens, fish, birds, animals and plants that live in the area become sick and die off quickly. This is a huge factor in the destruction of the wetlands, which rely heavily on groundwater to recharge their lakes and ponds after drought periods. In turn, people who use this land for hunting, fishing, and even for their own sources of clean water are affected by this type of pollution.

Sources of Groundwater Contamination

Sources of Groundwater Contamination

It’s always a good idea to be able to recognize what causes groundwater pollution so you can help step up and make a difference when you see it in your area. When it comes to this type of pollution, every source can be grouped into one of four categories: direct, indirect, manmade, and natural. Although natural sources of pollution often can’t be changed much, there is always something you can do about other sources.

1-Direct

When learning about what causes groundwater contamination, you should first start with direct contaminants, as these are the ones you’re more likely to come into contact with.

Hazardous waste. When hazardous waste is disposed of or dumped incorrectly, the chances of it spilling and leaching into soil and water are great. It’s very likely for this type of spill to occur and go completely unnoticed. Unfortunately, this is also true of more widely recognized hazardous waste spills, but there’s very little that can be done about it. Once a spill occurs, it can almost never be removed from groundwater.

Landfills. Landfills are another direct cause of pollution in groundwater. The longer a landfill remains full of waste, the more the toxins from that waste seep into the soil below and around the landfill. This leads to groundwater contamination almost immediately. When landfills are very large, the amount of groundwater polluted by them is significant.

2-Indirect

But what are some sources of groundwater pollution that are less direct?

Atmospheric pollutants. Sometimes, when surface water in the area becomes polluted, this can lead to those pollutants evaporating into atmospheric air and water. In turn, polluted air can drift into areas where humans are more present, and polluted rain can fall as acid rain. This damages the environment and can also cause serious health risks for people in the area, too.

Petroleum fuels. Diesel and gasoline are well-known indirect causes of groundwater pollution. In some instances, these fuels, when kept in underground storage, can leak significantly and seep into the ground around them, leading to groundwater contamination. Most of the time, however, the use of these fuels pollutes the atmosphere and leads to indirect atmospheric pollution of groundwater through the rain.

3-Man-made

It’s no secret that human beings are a huge polluter of groundwater. These are just some of the manmade ways groundwater gets contaminated.

Septic systems. In much of the United States, city-based water and sewage are unavailable, especially in very rural areas. When this is true, septic systems are usually the go-to solution to provide running water and plumbing to people in these regions. Septic systems are very common in the U.S., and in most cases, they aren’t supposed to cause any groundwater contamination at all. Unfortunately, sometimes they are installed incorrectly or become damaged over time without regular maintenance. This causes human waste to leach into the surrounding soil, which in turn causes a lot of pollution very fast.

Chemicals. Road salts, solvents, and chemicals used on roads, in lawns, and around the home are some of the leading manmade causes of groundwater pollution. When these products are used on land surfaces or homes, they are easily washed away by natural rainfall. From there, since there’s nowhere else for them to go, they seep into the soil and reach the groundwater quickly. When humans and animals then drink this water, they are ingesting these chemicals, which can cause major health problems very fast. Also, when groundwater that has been affected by these chemicals is then used in agriculture or industry, it is unable to provide the proper nutrients and hydration required to get the job done.

Pesticide. Much like chemicals and other man-made solutions, pesticide is prone to washing into the soil after heavy rainfalls, especially when it is used frequently by farmers and other members of the agricultural industry. The chemicals involved in pesticides are very dangerous for both human and animal consumption, and when they reach groundwater, they can almost never be completely removed.

4-Natural

Learning about groundwater contamination involves finding out more about natural contaminants like animal waste, which is not a major source of groundwater pollution.

Animal waste. Although animal waste is usually more of a problem for surface water contamination and often stays out of groundwater, this isn’t always the case. In some situations, especially where animal life is very prevalent, urine and feces left behind by animals seep into the ground and cause some pollution to the groundwater there. When this happens, the type of pollution caused by these contaminants is usually easy to remove by water treatment facilities. However, it does make groundwater unsafe to drink without treatment.

Arsenic. Sometimes, arsenic is naturally present in rocks. When groundwater passes through or sits in these rocks for too long, it can cause arsenic to build up in the groundwater to levels that are capable of poisining animals or people who drink it. This is rare, but it does occur, especially in areas where mining has been present and might have exposed these types of rocks. Again, regular water treatment can usually remove arsenic from groundwater.

Radon. Radon gas is also another natural pollutant that can nevertheless cause serious problems. If a human being or an animal consumes water that has been polluted with radon gas, the results can be potentially fatal. Like the other types of natural pollution in groundwater, radon gas can sometimes be removed by treatment. However, it’s very important not to drink water that could have potentially been polluted with radon until it has been thoroughly tested by professionals.

The Importance of Groundwater

The Importance of Groundwater

Most of our drinking water in the United States comes from groundwater. In rural parts of the country, up to 99% of the water used for drinking is sourced from groundwater. Although this number is smaller in cities and more built-up areas, the total amount of drinking water in the United States that comes from groundwater sources is still 51%. This means that just over half of the water we drink comes from groundwater, which in turn means that if this water gets contaminated, we will have fewer clean drinking water sources throughout the country.

Most of the water used in agriculture in the United States comes from groundwater. Around the country, 64% of the water used in agricultural processes comes from groundwater sources. Once again, this means that issues with the groundwater can significantly impact human life, this time by cutting back on healthy and successful crop growth. As more and more farmers rely on groundwater to grow their crops, the importance of keeping this water source clean grows.

Surface water cannot recharge without groundwater. It’s very important to the environment and the whole planet to replenish wetlands, swamps, lakes, and rivers after periods of drought. When groundwater is present, this water can be used as a source of refill and recharge for these important ecosystems. However, when groundwater is contaminated or not present at all, these parts of the environment suffer significantly. This can have major impacts around the world.

Where surface water isn’t present, groundwater often still is. There are many parts of the United States as well as the world that rely heavily on groundwater to provide drinking water as well as water for other uses, simply because there isn’t a lot of surface water present. This is especially true in dry parts of the country, such as the western U.S. In other countries where clean drinking water is a major source of crises, groundwater is a crucial part of providing people with something safe to drink.

Groundwater doesn’t often have to be treated much. When it isn’t already contaminated, groundwater is usually much cleaner than surface water, and it requires far fewer harsh chemical treatments to make it safe enough for human consumption. Many contaminants that come from nature are also removed by nature as the water passes through rocks and sand that serve as filtration.

The Secret of Puquios

The Secret of Puquios

A team of researchers led by Rosa Lasaponara with the Institute of Methodologies for Environmental Analysis, in Italy has found evidence that suggests that the purpose of the spiral, rock-lined holes called puquios carved into the ground in an area near the 'Nasca lines' in Peru, were part of an ancient water distribution system. In their paper to be published in Ancient Nasca World: New Insights from Science and Archaeology, the team describes their study of the structures using satellite technology and what they believe their findings say about the Nasca people.

The Nasca people lived in the area from sometime before 1,000 BC to approximately 750 AD, which historians have noted, was remarkable because the area is one of the driest on the planet. Prior research has suggested that they were the creators of the famous 'Nasca lines' that cover the desert floor with huge images of geometric shapes, plants and animals. Some have suggested that the massive drawings are also part of a huge water movement project, possibly serving as markings for major parts.

People living in the Nasca region of Peru over the years, and some scientists. have been aware of the puquios for quite some time, many puzzling over their purpose. Most have suggested they likely had something to do with obtaining water, but until now, no one had any idea how that might have come about. Making matters worse was that because they were made with the same materials as the surrounding terrain, it was impossible to carbon date them, which might have proved that they were actually constructed during the time of the Nasca people. To unravel the mystery, the researchers turned to images taken from satellites—that allowed them to get a better perspective of where each of the puquios were in relation to one another.

After much analysis, the team reports that the evicence suggests that the puquios served as part of a vast hydraulic system that carried water in underground canals to where it was needed—either to water crops or into populated areas as drinking water. The puquios, they explained further, caused air to be pulled down into the underground canal system—the wind actually helped to push the water through the system, which meant they served as ancient pumps.

This, the team suggests, indicates that the underground water system allowed the people access to water the whole year round. It also showed that the early people where highly technically advanced and extremely well organized. Making the system work and keeping it going would have required major effort and coordination. They note that some of the puquios were so well constructed that some of them are still in use today.

Hydrogeologist Job (sneak peek)

Hydrogeologist Job (sneak peek)

What Does a Hydrogeologist Do?

Hydrogeologists are a type of environmental geologist that study how water interacts with the natural environment of rocks and soils. People with these qualifications can carry out one of two jobs, but sometimes will be expert in both. The first role is that of environmental geographer. They study the relationship between water and rocks and soil as a natural process. Their data will help other experts understand such environmental processes as glaciation, river formation and movement, flood and other natural disaster risk and long-term environmental processes. They help us understand the world around us in terms of the relationship between water and dry land. They will look equally at data collected from the field, GIS analysis and old maps.

The second role of a hydrogeologist is to ensure that water supplies remain safe and healthy. Some rock and soils contain contaminants that are harmful to human health. It is their job to identify and mitigate them. Most of these will be naturally occurring contaminants, but they may also be the result of pollutants. They may provide expert analysis in litigation against the businesses responsible should a court case be necessary.

They may also be involved in environmental planning. The amount of waste that we produce requires space to put them. Hydrogeologists will look at the underlying soil and geology of proposed sites to ensure that pollution risks are low (for example subterranean rivers or lakes that flow into domestic water supplies). Land use planners will often consult hydrologists and hydrogeologists. They differ from hydrologists in that these professionals study surface water rather than how water changes the environment.

Where Does a Hydrogeologist Work?

Hydrogeology is closely related to hydrology and the Earth sciences, so they will have a good all round understanding of the environment. The largest employer of hydrogeologists at present is Federal government. They will work in a wide range of areas such as monitoring for bodies like the National Park Service, as researchers for the EPA and in legal (public prosecution). Around 28% of hydrogeologists work for the Federal government. Others will also work in academia and teaching.

Around 22% presently work for scientific and technical consulting services. These individuals will work independent of bodies and hired on a case by case basis. Government, private businesses and third sector organizations may hire them for a specific task per contract. Similarly, the 17% who work for engineering services will be hired for the same sort of role by (typically) civic engineering and construction companies, or they may work on projects that their employer manages.

17%and 9% respectively work for state and local government. Their roles will be similar to the Federal government jobs but at a local level. Regardless of which sector they work in, their role will be a mix of office work and fieldwork.

What Is the Job Demand for Hydrogeologists?

Like other geoscientists, hydrologists and geologists, demand for this sector is expected to grow around 7% between 2014 and 2024. This is the average across all jobs. As demand for environmental services increase, so too will experts in various fields. There may be a demand increase in environmental mitigation, especially as natural disasters such as floods increase due to climate change. The broad scope of problems caused by floods exists beyond the damage caused by the actual flood, but also public health and ecology.

What Are the Education Requirements to Become a Hydrogeologist?

At minimum, candidates will require a bachelor's degree for the majority of entry level jobs. Students should take a degree in environmental science, geography, geology, earth sciences or related. Physics will also be an advantage, as will geoengineering. Students should tailor their minors and electives to environmental subjects. You should also consider taking math related subjects, specifically statistics, as this will aid your analytical work.

As hydrogeology concerns much fieldwork, you are advised to study master's degrees where possible. This will provide experience and understanding of the sort of project work that you can expect to carry out in your career. MA/MS courses are highly advisable and will be essential in areas where there is much competition.

A doctorate will be required for teaching and research roles at colleges and universities. Although those wanting to go into environmental law may find the higher qualifications help them develop in their career.

History of Hydrogeology

History of Hydrogeology

-Early 17th century – groundwater was believed to be seawater pumped up into the land by either tidal forces or air pressure, Some major advances in the development of hydrogeology as a science:

- In the latter part of the 17th century Pierre Perrault conducted hydrologic investigations in the Seine River basin First person to use a water balance approach to hydrogeology; he established that the local annual precipitation was more than ample to account for the annual runoff.

- Henri Darcy, a French hydraulic engineer, concluded that the rate of flow of a fluid through a porous media is directly proportional to the energy loss and inversely proportional to the length of the path of flow (1856).

- Arsène Dupuit (another French engineer) extended Darcy's work and developed equations for
underground flow toward a well, for the recharge of aquifers, and for the discharge of artesian wells.

- O.E. Meinzer (American scientist with the US Geol. Survey) published several seminal documents on the subject, including his 1923 USGS Water Supply Paper 489 (The occurrence of groundwater in the United States with a discussion of principals) and the 1942 book titled Hydrology.

- In 1935, C.V. Theis recognized the analogy between groundwater flow and heat flow. Why is this
important?

• At that time the mathematical characterization of heat flow was well developed, while the mathematics of groundwater flow were not
• Understanding the mathematics of heat flow allowed him to develop analytical equations for flow to wells; these are widely used in aquifer pumping test analysis and drawdown predictions

- In 1940, M. King Hubbert developed the theory that describes flow in large groundwater basins Identified the difference between regional and local flow systems

 

- Also in Jacob put forth groundwater flow theory that incorporates the elastic behavior of porous rocks
1940,

- In early 1960s, J. Tóth took Hubbert’s theoretical treatment of regional flow systems and Jacob’s
mathematics and used a computer to generate one of the first computer groundwater models

- 1970’s and 80’s: environmental and contamination issues became important; also research on
potential use of geothermal energy

- 1984: McDonald and Harbaugh publish the first version of MODFLOW

- 1990’s: drastic technological advances in personal computers makes groundwater modeling
widespread and available to everyone

- Current issues and contemporary areas of research:

• Groundwater resource studies, especially concerning water availability determination and long-term sustainability of groundwater resources.
• Flow in “non-porous media” (i.e., fractures and karst conduits), especially related to flow modeling and contaminant transport
• Effects of long-term climate change on groundwater resources