The previous article reviewed the indicators of air pollution and their use in economic studies. This article focuses on a number of water pollution indicators and their use in economic studies. This is because indicators of water pollution help analyse the impact of economic growth on the environment. Water pollution refers to the contamination of water by toxic elements and harmful chemical agents. It implies an alteration in the natural state of water including its physical, chemical and biological properties. Water pollution due to chemicals from industrial toxic releases. Pollution level in water can be classified into two categories:
- chemical or physical indicators and
- composite organic indicators (Shanghai.Gov, 2018).
Physical indicators of water pollution
Physical indicators of water pollution include water temperature, colour, odour, turbidity, transparency, pH, salinity, conductivity, oxidation-reduction potential and the level of carbon dioxide among others.
- Water temperature– Temperature of water is a crucial factor as it affects the physical and chemical properties of water. Some of these properties include the level of dissolved oxygen and other gases, pH, water density, and salinity (Fondriest Environmental, 2016). Pollution of water alters its temperature and adversely affects water quality. However this, in turn, has a negative effect on aquatic life.
- Turbidity, transparency and pH– Transparency and turbidity are just the opposite of each other denoting the state of water quality. Transparency of water refers to its clean state whereas turbidity is the number of waste materials in a sample of water. Increase in turbidity also results in a rise in the water temperature. On the other hand, pH indicates the water temperature. An increase in water temperature increases its pH value and vice versa.
- Salinity– Salinity serves as a significant indicator of water quality through the determination of its chemical composition. It is the total amount of mineral components present in water (Berezina, 2003).
- Conductivity– Conductivity, or the electrical potential of ions, increases with a rise in water temperature and decreases with a fall in it. The conductivity of polluted water is higher than that of clean water.
- Level of carbon dioxide– The presence of carbon dioxide in water is mainly due to the decomposition of organic matters and other sediments (Shanghai.Gov, 2018). Therefore, water pollution involving organic wastes causes an increase in carbon dioxide.
Composite indicators of water pollution
Composite indicators of water pollution include the level of dissolved oxygen, total organic carbon, total phosphorus, total nitrogen and ammonia among others. These types of indicators denote the amount of corresponding element present in the organic matters that are dissolved in water.
- Level of dissolved oxygen–Dissolved oxygen is extremely crucial and essential for aquatic life. It is also an important indicator of water pollution as wastewater typically contains low level of oxygen. This results in the death of fishes and other organisms. The expected level of dissolved oxygen in water is 4 to 12 milligrams per litre (Lower Colorado River Authority, 2018).
- Total organic carbon– Total organic carbon indicates the level of organic pollution by determining the carbon content in the organic matters present in water.
- Total phosphorus– Phosphorus is toxic for human bodies and its presence in water results in adverse health effects for humans.
- Ammonia– When microorganisms react with organic compounds containing a high level of nitrogen, it generates ammonia (Shanghai.Gov, 2018). It is harmful to aquatic life and is an indicator of water pollution.
- Total nitrogen– Level of nitrogen in dirty water is greater than that in clean water. It is useful in the process of growth of many microorganisms which reduce the level of dissolved oxygen. High level of total nitrogen in water is indicative of water quality deterioration.
Use of water pollution indicators in economic studies
The table below shows some of the recent economic studies and the use of water pollution indicators in their analysis.
Study and indicators of water pollution using
|(Jorgenson, 2007)||Investigating the association of foreign investment in the manufacturing sector in developing countries with environmental pollution as the study objective. On the other hand, for less developed countries, organic water pollutants was the indicator.|
|(Muyibi, Ambali, & Eissa, 2008)||In order to examine the effect of development activities on water pollution in Malaysia, the authors used water pollution index with ammoniacal nitrogen, suspended solids and pH value to estimate the impact of the industrial growth of manufacturing industries, GDP and urbanisation.|
|(Lee, Chiu, & Sun, 2010)||In order to test the relationship hypothesised by the environmental Kuznets curve, the authors examined a sample of 97 countries for the time period 1980 to 2001. They used a generalised method of moments technique to establish the relationship between real income and water pollution indicator of biological oxygen demand.|
|(Avazalipour et al, 2013)||Finding the relationship between FDI and environmental quality was the main objective of the study. For this purpose, the researchers also used biological oxygen demand as the indicator of water pollution.|
|(Greenstone & Hanna, 2014)||The study was an in-depth assessment of environmental regulation in India with respect to air pollution and water pollution. As water pollution indicators, these researchers also used biochemical oxygen demand, dissolved oxygen and faecal coliforms.|
|(Choi et al, 2015)||In order to study the environmental Kuznets curve hypothesis in South Korea, the researchers examined the relationship between GDP and biochemical oxygen demand and chemical oxygen demand in four major rivers of the country.|
Table 1: Summary of a few economic studies using water pollution indicators
Importance of water quality indicators
Water quality and safety are one of the fundamental factors for human development according to the World Health Organization as they directly affect human well-being (WHO, 2018). As an international institute of public health, WHO coordinates efforts across countries and communities in order to ensure access to safe water. It is therefore important for the concerned authorities to allocate resources for water quality management. Moreover, discussed indicators can also help in studying the relationship between growth and environment. Furthermore the proceeding articles in this study attempt to establish the impact of foreign direct investment on these water pollution indicators.
- Avazalipour, M. S., Zandi, F., Saberi, R., Hakimipour, N., & Damakeshideh, M. (2013). The Impact of FDI on Environmental Resources in Selected Countries (Non- OECD). International Journal of Research and Reviews in Applied Sciences, 17(1), 111–115.
- Berezina, N. A. (2003). Tolerance of Freshwater Invertebrates to Changes in Water Salinity. Russian Journal of Ecology, 34(4), 261–266.
- Choi, J., Hearne, R., Lee, K., & Roberts, D. (2015). The Relation between Water Pollution and Economic Growth using the Environmental Kuznets Curve: a Case Study in South Korea. Water International, 40(3), 499–512.
- Fondriest Environmental. (2016). Water Temperature – Environmental Measurement Systems. Retrieved July 11, 2018, from https://www.fondriest.com/environmental-measurements/parameters/water-quality/water-temperature/.
- Greenstone, M., & Hanna, R. (2014). Environmental Regulations, Air and Water Pollution, and Infant Mortality in India. American Economic Review, 104(10), 3038–3072.
- Jorgenson, A. K. (2007). Does Foreign Investment Harm the Air We Breathe and the Water We Drink? A Cross-National Study of Carbon Dioxide Emissions and Organic Water Pollution in Less-Developed Countries, 1975 to 2000. Organization & Environment, 20(2), 137–156.
- Lee, C. C., Chiu, Y. Bin, & Sun, C. H. (2010). The Environmental Kuznets Curve Hypothesis for Water Pollution: Do Regions Matter? Energy Policy, 38(1), 12–23.
- Lower Colorado River Authority. (2018). Water Quality Indicators. Retrieved July 11, 2018, from https://www.lcra.org/water/quality/colorado-river-watch-network/Pages/water-quality-indicators.aspx.
- Muyibi, S. A., Ambali, A. R., & Eissa, G. S. (2008). The Impact of Economic Development on Water Pollution: Trends and Policy Actions in Malaysia. Water Resources Management, 22(4), 485–508.
- Shanghai.Gov. (2018). What are the water pollution indices? Retrieved July 11, 2018, from http://www.shanghai.gov.cn/shanghai/node27118/n31193/n31212/u22ai71924.html.
- WHO. (2018). Water Safety and Quality. Retrieved July 11, 2018, from http://www.who.int/water_sanitation_health/water-quality/en/.