Air Pollution: Biomonitoring For A Greener Future

Biomonitoring is a technique used to study the biological responses of organisms such as plants and animals to air pollution. It is a qualitative and quantitative approach to pollution control that provides information on the health of an ecosystem. Biomonitors are organisms that accumulate pollutants within their tissues and can be used to detect the presence and impact of pollutants in the environment. Plants, for example, exhibit different damage symptoms when exposed to different air pollutants, allowing for the determination of the species and concentration of pollutants. This method of biomonitoring is simple, cost-effective, and reliable compared to traditional monitoring methods. It has been used in various studies to assess air pollution levels and their impacts on the environment and human health.

Plants and lichens as bioindicators

Biomonitoring is a technique used to study biological responses to air pollution. Bioindicators provide a pollutant measurement that can be compared with an instrument measurement, offering a "snapshot" of an ecosystem's health. Plants and lichens are both used as bioindicators of air pollution.

Plants as Bioindicators

Plants are an economic, simple, and reliable method of monitoring air pollution. They exhibit different damage symptoms depending on the type of air pollutant, which can be used to determine the species of pollutant and its concentration. For example, ozone bioindicators are certain plants that exhibit distinct leaf injuries with locally elevated ozone concentrations. Some plants that have been used as bioindicators include morning glory, petunia, black poplar, red clover, and tobacco.

Lichens as Bioindicators

Lichens are sensitive to atmospheric pollution, such as nitrogen, because they receive all their nutrients and water from atmospheric deposition. Nitrogen deposition can harm and kill the algae's chlorophyll, which feeds the fungi. Scientists monitor lichen communities, and if there is an increase in nitrogen-tolerant species and a decrease in nitrogen-sensitive species, this may indicate an increase in atmospheric nitrogen deposition. Lichens can also be used to monitor mercury deposition.

Monitoring air quality

One common method of biomonitoring is the use of bioindicators, which are organisms that exhibit specific responses to environmental pollution. Plants, for example, show distinct damage symptoms when exposed to different air pollutants. By observing these symptoms, scientists can determine the type and concentration of pollutants in the atmosphere. This method is simple, cost-effective, and reliable compared to traditional monitoring techniques. Additionally, the use of bioindicator plants allows for the detection of phytotoxic levels of O3 pollution, which is crucial for establishing air quality standards to prevent harmful effects.

Another concept in biomonitoring is bioaccumulation, where organisms accumulate pollutants within their tissues over time. These organisms, known as bioaccumulators, can provide valuable information about the exposure of an ecosystem to a particular pollutant. For example, moss transplants have been used to assess air quality around an oil refinery, with the accumulation of pollutants in the moss bags providing stable measurements. Similarly, native moss surveys in Poland monitored heavy metal pollution levels over several decades, highlighting the changes in air quality despite the implementation of environmental protection legislation.

Biomonitors, on the other hand, provide quantitative information on the health of an ecosystem. They accumulate contaminants, facilitating analytical measurements and helping identify polluted areas. Biomarkers are also essential in biomonitoring, as they represent biochemical, cellular, physiological, or behavioural variations in organisms exposed to chemical pollutants. These biomarkers provide evidence of exposure and potential toxic effects, making them valuable tools for risk assessment and management.

Overall, biomonitoring is a versatile and indispensable tool for assessing air quality and the impacts of air pollution. It complements physicochemical techniques of air pollution measurements and provides fundamental information for environmental and health risk assessments. By utilizing various concepts such as bioindicators, bioaccumulation, biomonitors, and biomarkers, we can gain valuable insights into the effects of air pollutants and work towards mitigating their negative consequences.

Assessing the health of an ecosystem

Biomonitoring is an important technique for assessing the health of an ecosystem by evaluating the negative effects of air pollution on vegetation. It is a qualitative and quantitative approach to pollution control, providing information on the quality of the environment and the actual condition of an ecosystem. This technique has been used for over 60 years to study biological responses to air pollution, and specific responses to environmental pollution among organisms such as plants and animals are represented as biomarkers.

Plants are commonly used in biomonitoring as they are economic, convenient, and credible indicators of air pollution. They exhibit different damage symptoms depending on the type of air pollutant, which can be used to determine the species of air pollutants. For example, in a study by De Agostini et al. (2020), moss transplants were used to assess the air quality around an oil refinery in Sardinia, Italy, over 16 years. The study found that the distance from the contamination source and rainfall influenced the element content in the biomonitor.

Bioaccumulators are another type of organism used in biomonitoring. They accumulate pollutants within their tissues and are good indicators of the exposure of an ecosystem to a pollutant. For example, native mosses have been used as indicators of heavy metal air pollution levels in Poland since the 1970s.

Biomonitoring can also be used to assess the accumulation of pollutants in plant tissue, which has been used to assess the effects of many pollutants, such as atmospheric nitrogen deposition. Changes in species composition or diversity can also provide valuable information about the impacts of emissions and the status of an ecosystem.

In addition to plants and bioaccumulators, lichens are also considered good bioindicators of air pollution as they show changes in their components, such as chlorophyll content or respiration level, in response to environmental air factors. Biomonitoring programs are often framed by government organizations and are essential for evaluating risks to human health and the environment.

Bioaccumulation in organisms

Bioaccumulation is a critical concept in environmental science that addresses the gradual build-up of chemicals or substances in an organism's body, often leading to harmful levels over time. This process is necessary for an organism to grow and develop, but the accumulation of harmful substances can also occur. These harmful substances enter the body of an organism through various pathways such as ingestion, skin contact, or respiration. Over time, these substances can accumulate in body tissues, particularly in fat, due to their inability to be easily metabolised or excreted. This is because some chemicals are fat-soluble and easily dissolve in fats rather than water, and are thus stored in fat tissues, making them harder to get rid of. For example, many fish have fat deposits where chemicals can accumulate over time.

The phenomenon of bioaccumulation is particularly important in aquatic ecosystems, where marine organisms such as fish, plants, and shellfish may absorb harmful substances from the water and their food. These harmful substances enter aquatic ecosystems through various pathways, including agricultural and urban runoff, industrial effluents, and atmospheric deposition. For example, factories may discharge untreated or partially treated wastewater containing heavy metals and organic pollutants into rivers and oceans. Atmospheric deposition occurs when pollutants deposit from the air onto water surfaces, including particles and gases. Each of these pathways contributes to the accumulation of pollutants in aquatic environments, posing risks to aquatic organisms.

Bioaccumulation can have serious impacts on ecosystems, disrupting food chains, harming wildlife, and decreasing biodiversity. When harmful substances build up in one organism, they can affect the entire food web. Many animals rely on each other for food, so pollution in one organism can affect others. Animals at the top of the food chain, including humans, are at greater risk of accumulating high levels of pollutants. This phenomenon is known as biomagnification, where the concentration of pollutants increases at each level of the food chain, leading to dramatic changes in ecosystem dynamics.

Human activities significantly contribute to the levels and spread of bioaccumulative substances in the environment. Industrialisation, agriculture, and waste management practices are among the key drivers of chemical dispersion, leading to increased instances of bioaccumulation. For example, pesticides and fertilisers used in farming can wash into rivers and lakes, concentrating in aquatic ecosystems and the organisms that inhabit them. Similarly, improper waste disposal can lead to pharmaceuticals and chemicals leaching into the surrounding environment, entering food chains through soil and water contamination.

Addressing bioaccumulation requires cooperation between governments, industries, scientists, and the public. Sustainable agriculture practices, such as organic farming, crop rotation, and integrated pest management, can help to minimise the use of pesticides and fertilisers, thereby decreasing the contamination of soil and water. Proper waste management and disposal are also essential for preventing contaminants from entering the environment. Bioremediation is an eco-friendly approach that utilises microorganisms and plants to detoxify contaminated environments, offering a sustainable and natural solution to pollution.

Biomonitoring as a forensic tool

Biomonitoring is a useful tool for forensic analysis of air pollution. It can be used to understand potential exposures to specific sources of pollution and to identify historical elevations in exposure. It is a qualitative and quantitative approach to pollution control, with biomonitors providing quantitative data on the health of an ecosystem.

Biomonitors can be used to detect the presence of pollutants and to quantify their impact on an organism or ecosystem. They are particularly useful for detecting pollutants that are difficult to measure analytically, as very low exposure rates can accumulate in biological systems over time, eventually reaching quantifiable levels. This is especially relevant for Persistent Organic Pollutants (POPs), which are characterised by persistence in biological systems, limited metabolism, slow elimination, and bioaccumulation.

Biomonitoring can be active or passive. Active biomonitoring involves the deliberate introduction of plants, while passive biomonitoring examines organisms already present in the ecosystem. Passive biomonitoring was used in a study of air pollution around an oil refinery in Sardinia, where moss transplants were used to assess air quality over 16 years. The study found that the distance from the contamination source and rainfall influenced the element content in the biomonitor.

Plants are a common tool for biomonitoring, as they exhibit different symptoms in response to different pollutants. These symptoms can be used to determine the type and concentration of pollutants, and the time of exposure. For example, certain plants can be used to monitor SO2, and will exhibit visible symptoms after a certain concentration of SO2 has been present for a certain amount of time.

Well-designed biomonitoring schemes can help focus risk assessment and management efforts, and demonstrate the effectiveness of control measures.

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