compounds (VOCs) including chemicals like toluene, styrene, phosgene, gasoline additives, and adhesives, and microorganisms like Salmonella, Vibrio cholera, and Shigella, also contribute to chronic diseases like typhoid, fever, vomiting, diarrhoea, dysentery, gastroenteritis, and cholera (Council 2009; Soni et al. 2018).
Generally, water spoiled with pollutants causes different health problems to humans, plants, and aquatic life (which directly/indirectly affects humans). Exposure to these noxious wastes lead to chronic poisoning characterized by neurological, gastrointestinal, and cardiovascular problems, and liver damage (Dada et al. 2016).
Fluoride in water is essential for protection against bone weakening but concentration above 0.5 mg/L leads to fluorosis. Ingesting large quantities of Cu‐contaminated water causes diarrhoea, fever, liver, and kidney damage. Exposure to PFAS can lead to fertility problems, cholesterol rise, cancer, and thyroid problems. According to the Environmental Protection Agency, a person’s exposure to PFAS should be less than 70 parts per trillion and in Hoosick Falls, it was detected to be 1 30 000 parts per trillion (Michaels 2017).
Long‐term Cd exposure by consuming the food crops irrigated by effluents may cause kidney and skeletal damage (Friberg and Vahter 1983). Infants and pregnant ladies consuming Lead (Pb) contaminated water can experience developmental delay, abdominal pain, birth defects, hypertension, and preeclampsia. Pb contaminates in drinking water from pipes, solder, and household plumbing systems and affects the blood, central nervous system, and kidneys. Flint, Michigan, is an example in this regard. The city officials decided to start using Flint River as an alternative point water source for short period of time in 2014. The new water pipeline was built but not treated with any anti‐corrosive agent to deter Pb contamination. Studies revealed that this negligence led to increase in the blood lead levels by a factor of two, three, or more, which actually causes many skin‐related problems (Grossman and Slutsky 2017).
Metallic Hg is an allergen which may cause oral lichen and damage to the nervous system. The Minamata case is the best known example, where the Minamata Bay was contaminated by high content of Hg discharge. Around 2000 were poisoned; hundreds of deaths were reported from Minamata disease, which arises due to the consumption of fish containing methyl mercury (Mishima 1992). Intake of large quantities of arsenic (As) metal for long periods of time leads to haemolysis, melanosis, polyneuropathy, bone marrow depression, etc.
Accumulation of heavy metals also affects the aquatic flora and fauna and constitutes public health problem when contaminated species are used for food. It has been reported by World Health Organisation (WHO) in 2019 that transmitted diseases from polluted water like diarrhoea, pneumonia, typhoid, cholera, polio, etc. cause more than 4 85 000 deaths per year (WHO, 14 May 2019). Despite affecting human health, water pollution also has an adverse effect on plants. Nutrient deficiency in water ecosystem, excess use of agricultural chemicals, etc. hinders plant growth and also poisons the plant.
Though we have made technological advancements in the previous decades, the lack of sustainable usage and pretreatment solutions have made thousands of rural towns unavailable of safe potable water. As per the WHO report, two million people received groundwater comprising contaminants like arsenic, radium, and fluoride ions. It is not surprising that thousands of communities could not afford to filter these pollutants off and intake the same polluted water (Shannon et al. 2010). Here, it should be mentioned that heavy metal sources are the major source in water deterioration.
The chapter discusses all the above mentioned aspects and is divided in sections. The first section addresses the general introduction of water quality. The second section emphasizes the different sources of the major pollutant, i.e. heavy metal contamination in groundwater for detailed study. The third part of this chapter contributes to the type of pollution. This section emphasizes heavy metal pollution. In the fourth section, we have discussed the effect of heavy metal pollution on human body. The fifth and sixth sections throw light on recent strategies to control water pollution and remediation of heavy metals. We have discussed the future strategies adopted by different governments and suggest some measures to remove these exudates in the water. At last, this chapter ends with future expects and conclusions drawn.
4.2 Sources of Heavy Metal Contamination
Pollutants can enter the water bodies from various sources and then get transported along the streamline. Legal and illegal discharges from factories, spills and leakages in underground oil pipelines or during transportation, hydraulic fracturing operations, and sewer overflows pollute various water discharge bodies. Other potential sources include radiation leaks from nuclear power plants and drinking water disinfection processes.
This can be broadly categorized under pointed and non‐pointed sources. Pointed sources refer to pollutants that enter the waterway through traceable sources like industrial outlet pipes, domestic sewage outlets, etc. It should be noted that most of these pointed sources are due to human intervention and untreated waste discharge. Non‐pointed sources refer to diffused contamination of water bodies through activities like leaching, littering garbage, etc., which cannot be monitored and controlled owing to the difficulty of tracing them. The sources of heavy metal pollution in water can also be categorized as natural as well as anthropogenic. These are discussed in brief in Figure 4.1.
Figure 4.1 Sources of heavy metal pollution in ground water and their effects on human health.
4.2.1 Natural Sources
Natural sources like geothermal and volcanic activity and rock weathering are some natural sources known to play their part in contamination of water sources. Rainwater is also a common source of water contamination as it dissolves air pollutants and transports them in groundwater, as is the case in acid rain. Moreover, the rock oxidation, sea intrusion, decay of radioisotopes (uranium‐enriched bedrock), and surrounding vegetation add on to these contaminants in water sources. Rock oxidation and rock weathering are also some natural activities that are major causes of heavy metal pollution (Talabi and Kayode 2019).
4.2.2 Anthropogenic Sources
Anthropogenic sources (caused by human activity) are the main source of heavy metal pollution. Industries and chemical companies directly discharge contaminated water without any pretreatment in groundwater and surface water sources. On the other side, agricultural irrigation is a huge reason for the degradation of drinking water quality owing to excess use of various types of harmful pesticides, fertilizers, and insecticides for crop production (Talabi and Kayode 2019). Other reasons for water pollution are discharge of sewage waste (wastewater, waste dump, and solid waste), exoneration of the by‐products and wastes produced by mining activities, dissociation of radioactive elements, over pumping, etc. The discharges of waste chemicals (inorganic and organic) by laboratories, experimental wastes which are directly thrown in water, are some types of anthropogenic sources which deteriorate the water quality. These anthropogenic activities are more toxic and harmful for humans as well as animals.
4.2.3 Point Sources
Point sources are recognizable, quantifiable, and controllable sources. The drainage pipes of industries and factories that directly break out into the water, oil spilling by oil ship and tankers, and discharge of municipal and sewage waste are all major point sources of water pollution. The other point sources are domestic, hospital, industrial, and mining wastes. The domestic wastes that occur from residence, faculties, institutions, and laboratories are major threats to human health because these sources directly pollute the drinking water. While the industrials and landfills are vital sources, heavy metal pollution is a huge cause of contamination of groundwater as well as surface water (Talabi and Kayode 2019).