Ecotoxicology: The Study of Toxic Chemicals in the Environment
1. Introduction
Ecotoxicology is the study of the effect of toxic chemicals on ecosystems. It includes the study of how these chemicals move through food chains and what effect they have on individual organisms, populations and communities.
The main goal of ecotoxicology is to protect the environment and human health by reducing the risks posed by toxic chemicals.
Ecotoxicology is a relatively new scientific discipline, arising in the 1970s in response to public concern about the impact of pesticides on the environment.
2. Ecotoxicology
-What is ecotoxicology?
Ecotoxicology is the study of the effect of toxic chemicals on ecosystems. It includes the study of how these chemicals move through food chains and what effect they have on individual organisms, populations and communities.
-History of ecotoxicology
The history of ecotoxicology can be traced back to the early days of pesticide use in agriculture. In the 1930s, chemists working for agrochemical companies began to develop synthetic pesticides, such as DDT and other organochlorines. These pesticides were very effective at controlling pests, but they also had a range of negative side effects. They were found to accumulate in the environment and build up in the food chain, causing harm to wildlife and humans alike.
In 1962, Rachel Carson’s book Silent Spring drew public attention to the harmful effects of DDT and other pesticides on the environment. This book sparked a wave of public concern about the impact of pesticides on the environment and led to calls for more research into their effects.
In response to this public concern, scientists began to study the environmental impact of pesticides in more detail. This work led to the development of a new scientific discipline called ecotoxicology.
-Ecotoxicology and the law
Ecotoxicology has played a key role in shaping environmental law and policy around the world. In many countries, government agencies use data from ecotoxicological studies when making decisions about which pesticides to approve for use and how to regulate them.
3. Weeds
-What are weeds?
A weed is defined as a plant that is growing where it is not wanted (Holm et al., 1997). Weeds can be both native or introduced species (Evans et al., 2016). Many weeds are capable of colonising disturbed habitats such as road sides, railway lines, construction sites, gardens and agricultural land (Evans et al., 2016). Once established, these plants can cause a range of problems including: competing with crops for water and nutrients; harbouring pests and diseases; reducing crop yields; and affecting human health (Evans et al., 2016). Weeds can also have negative impacts on native ecosystems by outcompeting native plants, altering soil properties and altering habitats (Evans et al., 2016).
Because of their negative impacts, there is a need to control weeds. Unfortunately, many traditional methods of weed control such as ploughing, hoeing and pulling by hand are labour intensive and often not very effective (Evans et al., 2016). As a result, chemical herbicides have become widely used as they are relatively cheap and easy to use (Evans et al., 2016). Unfortunately, herbicides can also have negative impacts on the environment, including harming non-target plants, animals and pollinators (Duke, 2010).
-Weeds in the wetland
Wetlands are habitats that are permanently or seasonally flooded with water (Dalrymple & Madsen, 1991). They can occur naturally or be created through human activities such as damming rivers or digging canals (Dalrymple & Madsen, 1991). Wetlands are important habitats for a range of plants and animals, including many that are rare or threatened with extinction (Dalrymple & Madsen, 1991). Unfortunately, wetland habitats are under threat from a range of human activities including drainage for agriculture, pollution and the introduction of invasive species (Dalrymple & Madsen, 1991).
One of the biggest threats to wetlands is the introduction of invasive plant species. These plants are often introduced accidentally through activities such as water transportation or soil movement (Nentwig et al., 2010). Once introduced, these plants can spread rapidly and dominate wetland ecosystems (Nentwig et al., 2010). This can have a range of negative impacts including altering water quality, changing habitat structure and reducing native biodiversity (Nentwig et al., 2010).
Chemical herbicides are often used to control invasive plants in wetlands. However, this can be problematic as many herbicides are non-selective and will kill any plant they come into contact with (Duke, 2010). This can lead to the loss of native vegetation and the negative impacts that come with it. Furthermore, herbicides can persist in the environment and be transported into other areas through runoff or leaching (Duke, 2010). This can cause damage to non-target plants and animals, as well as polluting waterways.
4. Pests
-What are pests?
A pest is an organism that causes harm to humans or their activities (Croft, 1990). Pests can be both plant and animal species. They can cause a range of problems including: crop damage; human health concerns; and economic losses (Croft, 1990).
Pests often occur in agricultural situations where they feed on crops or stored food products. This can cause yield losses which can have a significant economic impact on farmers (Croft, 1990). In addition to crop damage, some pests can also transmit diseases to humans or livestock which can have serious consequences for human health (Croft, 1990).
There are a range of methods that can be used to control pests. These include physical methods such as trapping or hand picking; biological methods such as using predators or parasites; and chemical methods such as using pesticides (Croft, 1990).
-Pests in the wetland
Wetlands are often home to a range of insect pests. These insects can damage crops that are grown in wetland areas or they can bite humans and animals, causing irritation and discomfort (FAO, 2006). In addition to causing direct harm to humans and animals, these pests can also transmit diseases such as malaria and Dengue fever (FAO, 2006).
Chemical pesticides are commonly used to control insect pests in wetlands. However, this can be problematic as many pesticides are non-selective and will kill any insect they come into contact with (FAO, 2006). This can lead to the loss of beneficial insects such as pollinators and predators, which can have a range of negative impacts. Furthermore, pesticides can persist in the environment and be transported into other areas through runoff or leaching (FAO, 2006). This can cause damage to non-target organisms, as well as polluting waterways.
5. Chemicals
-Glyphosate
Glyphosate is a broad-spectrum herbicide that is used to control a range of weeds (Mulla & Duke, 2009). It is effective against both annual and perennial plants (Mulla & Duke, 2009). Glyphosate is relatively safe to use and does not persist in the environment (Mulla & Duke, 2009).
-Altrazine
Altrazine is a herbicide that is used to control a range of weeds (Giesy et al., 2000). It is effective against both annual and perennial plants (Giesy et al., 2000). Altrazine is moderately toxic to mammals and does not persist in the environment (Giesy et al., 2000).
-Chlorpyrifos
Chlorpyrifos is an insecticide that is used to control a range of pests (Dukes, 2010). It is effective against both adults and larvae (Dukes, 2010). Chlorpyrifos is moderately toxic to mammals and does not persist in the environment (Dukes, 2010).
6. Conclusion
In conclusion, ecotoxicology is the study of the effect of toxic chemicals on ecosystems. It includes the study of how these chemicals move through food chains and what effect they have on individual organisms, populations and communities.
Ecotoxicology is a relatively new scientific discipline, arising in the 1970s in response to public concern about the impact of pesticides on the environment.
Ecotoxicology has played a key role in shaping environmental law and policy around the world. In many countries, government agencies use data from ecotoxicological studies when making decisions about which pesticides to approve for use and how to regulate them.