Water Pollution Monitoring: Advanced Techniques And Technologies

Water quality monitoring is essential for maintaining ecosystem health and ensuring safe drinking water for the population. It involves sampling and analysing water constituents and conditions, such as dissolved oxygen, bacteria, nutrients, pH, temperature, and introduced pollutants like pesticides, metals, and oil. Monitoring can be conducted at fixed stations, selected sites, temporary or seasonal sites, random sites, or on an emergency basis, such as after a spill. Data is collected by state, local, and federal agencies, as well as volunteer monitors, and entered into databases like STORET for analysis and reporting to organisations like the EPA. Water quality monitoring helps identify water pollution problems and guides pollution control and prevention efforts, with the ultimate goal of protecting human health and the environment.

Water quality monitoring methods

Water quality monitoring is a critical aspect of maintaining healthy aquatic ecosystems and ensuring safe drinking water supplies. Here are some commonly used methods for monitoring water pollution:

In-Situ (On-Site) Monitoring:

• Visual Assessment: This involves simply observing the water body for any signs of pollution, such as discolouration, foam, or floating debris. Trained observers can often identify potential issues through regular visual inspections.
• Dissolved Oxygen (DO) Testing: DO levels are a key indicator of water quality. Low DO levels can indicate pollution from organic matter or certain chemicals. Portable DO meters or probes are used to measure the amount of oxygen dissolved in the water.
• PH Testing: The acidity (pH) of water is important for aquatic life and can be affected by pollution. Handheld pH meters or test kits are used to measure the pH of water samples.

Laboratory Analysis:

Sample Collection and Testing: Water samples are collected from the site and sent to a laboratory for analysis. This allows for a more comprehensive assessment of water quality, including testing for specific pollutants such as heavy metals, pesticides, bacteria, and nutrients (nitrates and phosphates).

Remote Sensing:

Satellite Imaging: Satellites equipped with special sensors can provide valuable data on water quality over large areas. For example, they can detect changes in water colour, which may indicate the presence of algae or pollutants. This method is especially useful for monitoring coastal waters and large lakes.

Biological Monitoring:

Biomonitoring: This involves using aquatic organisms, such as fish, invertebrates, or algae, as indicators of water quality. Certain species are more sensitive to pollution, so their presence or absence can provide information about the health of the ecosystem. Biomonitoring is often used in combination with other methods to confirm the impact of pollution on aquatic life.

Real-Time Monitoring:

In-Situ Sensors and Probes: Technological advancements have led to the development of in-situ sensors and probes that can provide real-time data on water quality. These devices are placed directly in the water body and can measure various parameters, such as temperature, conductivity, turbidity, and even specific pollutants, depending on the sensor type.

Water quality monitoring is often a combination of these methods, providing a comprehensive understanding of the health of a water body. Regular monitoring allows for the early detection of pollution incidents, helping authorities take prompt action to mitigate potential environmental and health risks. It also assists in assessing the effectiveness of pollution control measures and ensures that water bodies meet the required standards for their designated uses.

Water pollution sources

Water pollution can be caused by a variety of sources, both natural and human-made. Natural sources of water pollution include excess soil erosion, dissolved solids, or excess growth of microorganisms, which can cause turbidity (cloudiness) and reduce light and oxygen levels in the water.

Human activities that generate domestic sewage and toxic waste are major contributors to water pollution. Improperly disposed of wastewater from industrial plants, chemical process facilities, and agricultural activities can introduce harmful chemicals and pollutants into water sources. Oil spills, for example, have devastating impacts on surrounding ecosystems, killing many marine species and creating "dead zones" where aquatic life cannot survive due to a lack of oxygen.

Non-point sources of pollution, which are the leading cause of water pollution in the United States, include agricultural fields, urban areas, and abandoned mines. Pollutants from these sources, such as herbicides, pesticides, fertilizer, oil, and animal waste, are carried by runoff into surface water bodies and groundwater. Point source pollution, on the other hand, can be traced to specific points of discharge, such as combined sewer systems during heavy rain, where untreated sewage and stormwater can overflow into water bodies.

Other human-made sources of water pollution include the discharge of cooling water from power plants, which can increase water temperatures and decrease oxygen levels, and the use of pesticides, metals, and petroleum products that can contaminate water through surface runoff. Additionally, radioactive waste from nuclear facilities, if not properly disposed of, can be extremely hazardous to the environment and human health.

Volunteer monitors and state and local agencies play a crucial role in collecting and analyzing water samples to identify these pollution sources and address water quality issues.

Water quality monitoring instruments

• Turbidity: Turbidity refers to the clarity of water, or how clear it is. This determines how much light penetrates the water and how deep it goes. Turbidity can be caused by excess soil erosion, dissolved solids, or excess growth of microorganisms, which can block light.
• Dissolved Oxygen: The amount of dissolved oxygen in water is important for the survival of aquatic species, such as fish and insect larvae. The concentration of dissolved oxygen can be influenced by factors such as temperature and the presence of organic debris.
• Temperature: Water temperature can affect the reactions that take place in the bodies of aquatic organisms, such as photosynthesis and digestion. Temperature also influences the amount of dissolved oxygen that water can contain.
• PH: The potential of hydrogen (pH) is a measure of the acidity of water, with values ranging from 0 (extremely acidic) to 14 (extremely basic) and 7 being neutral. Most water has a pH in the range of 6.5–8.5. pH can affect the toxicity of certain substances, such as ammonia.
• Pollution: Water quality monitoring instruments can be used to detect the presence and amounts of metals, pesticides, oil, and other pollutants in water.

Water quality monitoring can be conducted by various entities, including state and local agencies, volunteer monitors, and private entities. The data collected is used to assess water quality standards, identify pollution problems, and inform decision-making for pollution control and environmental management.

Water quality standards

Water quality criteria are set to protect designated uses, such as fishing, swimming, drinking water supply, and supporting aquatic life. These criteria include measuring the levels of chemical pollutants, dissolved oxygen, temperature, pH, turbidity, phosphorus, nitrates, total solids, conductivity, alkalinity, and fecal bacteria. Turbidity, for example, refers to the clarity of water and is influenced by factors such as excess soil erosion, dissolved solids, or excess growth of microorganisms, which can block light and affect aquatic plants and oxygen levels.

To design a water quality monitoring program, it is essential to first determine its purpose and select the appropriate parameters to monitor. For example, volunteers typically monitor basic parameters such as stream flow, dissolved oxygen, temperature, pH, and turbidity, while more sophisticated equipment may be required for detecting toxic substances like heavy metals and organic chemicals. By establishing water quality standards and conducting regular monitoring, municipalities, industries, and other water dischargers can obtain the necessary permits to operate while ensuring the health and safety of water ecosystems and the public.

Water quality monitoring programs

The US Environmental Protection Agency (EPA) plays a crucial role in supporting and conducting water quality monitoring. The EPA provides grants to states, eligible interstate agencies, and tribes to enhance ambient water quality monitoring programs. These grants enable the development and maintenance of monitoring programs and facilitate reporting of results to the EPA. The EPA also conducts its own limited monitoring through its Environmental Monitoring and Assessment Program (EMAP).

State and local water quality professionals, along with volunteers, have been monitoring water quality for many years. Volunteer monitors are trained citizens who regularly collect and analyse water samples, conduct visual assessments, and measure the biological health of water bodies. They provide valuable data that supplements state water quality information and guides local decision-making. Volunteer monitoring programs, such as Nature Forward's Water Quality Monitoring Program in Maryland, often focus on identifying benthic macroinvertebrates, which are small organisms that exhibit varying sensitivities to pollutants, providing insights into stream health.

Frequently asked questions