Groundwater Pollution: Unveiling The Silent Threat To Our Planet

by | May 25, 2023 | Water Pollution

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More than 1.5 billion people rely on aquifers for drinking water; it irrigates much of the world’s most productive agriculture and refills rivers and streams. The aquifer contains 97 per cent of the world’s fresh water. These critical services are now jeopardized. Human activities contaminate groundwater worldwide with hazardous substances such as nitrates from fertilizers and sewers, pesticides sprayed on fields, petrochemicals from leaking petrol tanks, and industrial solvents abandoned by enterprises leading to major groundwater pollution.

What Is Groundwater Pollution?

Groundwater pollution happens when pollutants are dumped into the earth and enter groundwater. Water pollution of this type can also occur naturally due to a tiny and undesired element, contaminant, or impurity in groundwater, usually called contamination instead of pollution. Groundwater pollution can arise from onsite sanitation structures, landfill leachate or effluent from wastewater treatment facilities, leaky sewers, petroleum stations, hydraulic fracturing (fracking), or excessive fertilizer application in agriculture. Naturally occurring pollutants, like arsenic or fluoride, can also cause pollution (or contamination). Using polluted groundwater endangers public health by poisoning or spreading water-borne diseases.

Groundwater Contaminants That Are Silently Attacking The Planet

Groundwater contaminants include physical, inorganic, organic chemical, bacteriological, and radiological characteristics. Many of the same chemicals that contribute to surface water pollution can also be detected in polluted groundwater, albeit their relative importance varies.

1. Arsenic And Flouride

The World Health Organisation (WHO) has identified arsenic and fluoride as the most severe inorganic pollutants in drinking water globally. Arsenic, a metalloid, can naturally occur in groundwater, as found most often in Asia, particularly in India, China, and Bangladesh. Natural arsenic pollution of groundwater impacts 25% of water sources in the shallower of two regional aquifers in the Ganges Plain of northern India and Bangladesh. The usage of arsenic-based insecticides has also damaged groundwater in specific locations. Arsenic in groundwater may additionally be found in areas where mineral extraction or mine waste dumps leach arsenic.

Naturally, fluoride in groundwater is becoming an essential issue as deeper groundwater is exploited, with over 200 million individuals at risk of drinking water containing elevated concentrations. When the hardness of water is low, fluoride is more easily liberated from acidic volcanic rocks and distributed volcanic ash.

2. Pathogens

Drinking water can get polluted with germs in faeces and urine due to insufficient sanitation and poorly located wells. Typhoid, cholera, and diarrhoea are examples of faecal-oral transmitted illnesses. The first three pathogen categories found in faeces (bacteria, viruses, protozoan organisms, and helminths or helminth eggs) are regularly detected in contaminated groundwater. In contrast, the comparatively large helminth eggs are typically filtered through the soil matrix.

Deep, constrained aquifers are generally regarded as the safest source of drinking water in terms of pathogens. Disease-causing organisms from wastewater that has been treated or not can pollute certain aquifers, exceptionally shallow ones.

3. Nitrate

The most frequent chemical contamination in worldwide groundwater and aquifers is nitrate. Nitrate concentrations in groundwater are high in some low-income nations, creating serious health concerns. It remains stable (does not decay) in high-oxygen environments. On-premises sanitation, sewage sludge disposal, and agricultural operations can all contribute to increased nitrate levels in groundwater. As a result, it could originate from an urban or farming origin.

4. Volatile Organic Compounds

Volatile organic compounds (VOCs) are harmful groundwater contaminants. They are commonly introduced into the environment due to irresponsible industrial practices. Aromatic hydrocarbons such as BTEX chemicals (benzene, toluene, ethylbenzene, and xylenes) and chlorinated solvents such as tetrachloroethylene (PCE), trichloroethylene (TCE), and vinyl chloride (VC) are among the primary VOC contaminants detected in groundwater. BTEX are critical components in petrol.

Polycyclic aromatic hydrocarbons, or PAHs, are another organic contaminant found in groundwater and produced from industrial activity. Naphthalene is among the most soluble and mobile PAH detected in groundwater due to its molecular weight, but benzo(a)pyrene is the most hazardous. In most cases, PAHs are formed as byproducts of partial combustion of organic materials.

Pathway Of Groundwater Contaminants

groundwater flow chart

1. Naturally Occurring

Natural arsenic pollution occurs due to organic materials in aquifer sediments, which create anaerobic environments. These conditions cause the bacterial breakdown of iron oxides in the deposition, releasing arsenic, which is ordinarily strongly bonded to iron oxides, into the water.

2. Sewage Sludge

Untreated sewage discharge can pollute groundwater, causing skin rashes, bloody diarrhoea, and dermatitis. This is particularly typical in areas with minimal wastewater treatment infrastructure or if the onsite sewage disposal system fails regularly. Along with diseases and nutrients, untreated sewage can contain significant amounts of heavy metals, which can leach into the groundwater system.

If treated wastewater from wastewater treatment facilities penetrates or is discharged to nearby surface water bodies, it may reach the aquifer. As a result, contaminants not eliminated in traditional wastewater treatment facilities may end up in groundwater.

3. Fertilizers And Pesticides

Nitrate can also infiltrate groundwater from excessive fertilizer use, such as manure spreading. This is because only a portion of nitrogen-based fertilizers is utilized to produce other plant-based products. The remainder settles in the ground or is lost as runoff. High nitrogen-containing fertilizer application rates and nitrate’s high water solubility result in higher runoff into surface waters and leaching into groundwater, resulting in groundwater pollution.

4. Industrial Leakage

Mineral extraction and metal processing plants are the principal sources of anthropogenic metals in groundwater, including arsenic. The low pH level related to acid mine drainage (AMD) increases the solubility of potentially harmful metals that may infiltrate the groundwater system.

5. Onsite Sanitation Systems

Depending on population density and hydrogeological circumstances, groundwater contamination with pathogens and nitrate can also arise from liquids penetrating the ground via onsite sanitation facilities such as septic tanks.

Groundwater Pollution Of Ganga River In India: A Case Study

The Ganga River Basin (GRB), considered a holy body of water for Hindus, suffers from severe arsenic poisoning. Because India accounts for 79% of the GRB, many states have experienced being affected. Uttarakhand, the state of Uttar Pradesh, Delhi, Madhya Pradesh, Bihar, Jharkhand, the state of Rajasthan, Chhattisgarh, Punjab, Haryana, and the West Bengal region are among the states affected. Arsenic levels in groundwater can reach 4730 g/L, irrigation water can reach 1000 g/L, and food materials can reach 3947 g/kg, all of which surpass the standards set by the United Nations Food and Agricultural Organization’s irrigation water standard and the World Health Organization’s drinking water standard. As a result, those exposed get disorders that impact their cutaneous, neurological, reproductive, and cognitive functions, possibly leading to cancer.

To address the growth in groundwater pollution in certain districts of India, the government has promoted sanitation development. The work has yielded results, reducing groundwater pollution and the risk of illness for mothers and children disproportionately affected by this issue. Based on the study, approximately 117,000 children under five years of age die each year as a result of drinking dirty water. The country’s initiative has achieved results in the country’s more economically developed areas.

To Conclude

Polluting substances such as nitrate and bacteria may be formed and keep seeping through the soil as pesticides, fertilizers, and animal manure combine and spread out on land. The contaminants will continue to sink until they reach groundwater sources. Groundwater pollution could significantly affect plants, animals, and humans who rely on contaminated groundwater to meet their basic needs. Furthermore, soil pollution from waste disposal tanks, landfills, and mining and quarrying sites could all contribute to groundwater pollution similarly.

Also ReadFive Ways To Conserve Water


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