Pesticides travel far and wide, endangering aquatic ecosystems

Sustainable Development Goals (SDGs) and the Impact of Pesticides on the Environment

Although nearly three million tons of agricultural pesticides are used across the globe each year, little is known about where these chemicals end up after their initial application.

Now, a team of scientists led by the University of Sydney has analyzed the geographical distribution of 92 of the most widely used agricultural pesticides, and discovered that about 70,000 tons of these potentially harmful chemicals leach into aquifers, rivers, oceans, and soils each year, impacting a variety of ecosystems and freshwater resources.

Daughter molecules

The study conducted by the University of Sydney found that nearly 80 percent of applied pesticides degrade into by-products known as “daughter molecules” that leach into the soil surrounding crops.

This degradation of pesticides often occurs as a ‘cascade’ of molecules into the surrounding environment, which can persist in the environment for a long time and can be just as harmful as the parent molecule or applied pesticide. One such example is glyphosate. Although it is highly degradable, it breaks down into a molecule known as AMPA that is both highly persistent and toxic.

River systems

While only a small fraction of pesticides was found to enter river systems after field application, once in the water, most of their active ingredients end up in the ocean. This negatively impacts marine wildlife and coral reefs, and often puts the very basis of marine and freshwater food chains at risk.

According to the researchers, 730 tons of pesticides enter rivers each year, causing about 13,000 kilometers of rivers to reach chemical concentrations above safety limits for a variety of aquatic plants and invertebrates.

Conservative estimate

Although the scientists used a large collection of publicly accessible geospatial data, the results are a conservative estimate, since some pesticides – such as legacy pesticides and those used in aquaculture, public spaces, and private dwellings – were not included in the analysis.

To mitigate the negative impact of pesticides leaching into the environment, officials should urgently adopt sustainable management strategies to promote reductions in field applications of harmful pesticides and set in place systems to effectively monitor their use under the 2030 Sustainable Development Agenda, concluded co-author Francesco Tubiello, a senior environmental statistician at the United Nations’ Food and Agriculture Organization.

Pesticides and the environment

Pesticides are substances used to prevent, destroy, repel, or mitigate any pest ranging from insects, animals, and weeds to microorganisms such as fungi, molds, bacteria, and viruses.

While they play a significant role in controlling pests that damage or hinder agricultural productivity, they can have negative impacts on the environment when not used appropriately or managed effectively.

Contamination of water bodies

Pesticides can reach water bodies such as rivers, lakes, and even oceans through run-off from agricultural fields or through leaching into groundwater. This contamination can disrupt aquatic ecosystems, harming or killing off certain species and leading to an imbalance.

Impact on non-target species

Pesticides are not always specific to the target pests. They can also impact non-target organisms, including beneficial insects, birds, and mammals. For instance, pesticides like neonicotinoids have been linked to the decline in bee populations, a serious issue given the critical role bees play in pollination.

Biodiversity loss

Through the above-mentioned mechanisms, pesticides can lead to a loss of biodiversity. By eliminating certain species or disrupting ecosystems, they can negatively impact the overall health of the environment.

Bioaccumulation and biomagnification

Some pesticides do not break down quickly and can accumulate in the environment or within organisms. They can also biomagnify, meaning they become more concentrated as they move up the food chain. This can lead to high levels of the chemicals in top predators, posing serious health risks.

Resistance

Pests can develop resistance to pesticides, requiring increasing amounts of the chemicals to achieve the same level of control. This can result in a vicious cycle of ever-increasing pesticide use, known as the ‘pesticide treadmill’.

Soil health impact

Pesticides can alter the balance of fungi and bacteria in the soil, reducing its fertility and leading to a reduction in crop yields over time.

Given these environmental concerns, many are advocating for more sustainable pest management strategies, such as integrated pest management (IPM) which relies on a combination of biological control, habitat manipulation, modification of cultural practices. Further research into alternative, less harmful pest control methods and stricter regulation of pesticide use is also part of the solution.

Source: Nature

By Andrei Ionescu, Earth.com Staff Writer

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SDGs, Targets, and Indicators

1. SDG 6: Clean Water and Sanitation

   • Target 6.3: By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials.
   • Indicator 6.3.2: Proportion of bodies of water with good ambient water quality.

2. SDG 14: Life Below Water

   • Target 14.1: By 2025, prevent and significantly reduce marine pollution of all kinds, particularly from land-based activities, including marine debris and nutrient pollution.
   • Indicator 14.1.1: Index of coastal eutrophication and floating plastic debris density.

3. SDG 15: Life on Land

   • Target 15.1: By 2020, ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services.
   • Indicator 15.1.1: Forest area as a proportion of total land area.
   • Indicator 15.1.2: Proportion of important sites for terrestrial and freshwater biodiversity that are covered by protected areas.

Analysis

The issues highlighted in the article are connected to several Sustainable Development Goals (SDGs), targets, and indicators:

1. SDG 6: Clean Water and Sanitation

The article discusses the leaching of agricultural pesticides into aquifers, rivers, oceans, and soils, impacting freshwater resources. This is directly related to SDG 6, which aims to ensure access to clean water and sanitation for all.

2. SDG 14: Life Below Water

The leaching of pesticides into rivers and eventually the ocean negatively impacts marine wildlife and coral reefs, as mentioned in the article. This aligns with SDG 14, which focuses on the conservation and sustainable use of marine resources.

3. SDG 15: Life on Land

The contamination of soils and freshwater ecosystems by pesticides is relevant to SDG 15, which aims to protect, restore, and promote sustainable use of terrestrial ecosystems. The article mentions the impact on aquatic plants and invertebrates in rivers due to pesticide pollution, highlighting the need for conservation and restoration efforts.

Based on the article’s content, the specific targets under these SDGs can be identified:

1. Target 6.3: Improve water quality

The leaching of pesticides into water bodies contributes to water pollution. Target 6.3 aims to improve water quality by reducing pollution and minimizing the release of hazardous chemicals and materials.

2. Target 14.1: Prevent marine pollution

The entry of pesticides into the ocean through rivers negatively impacts marine ecosystems. Target 14.1 focuses on preventing and reducing marine pollution from land-based activities, including nutrient pollution and marine debris.

3. Target 15.1: Conservation and restoration of ecosystems

The contamination of soils and freshwater ecosystems by pesticides highlights the need for the conservation, restoration, and sustainable use of terrestrial and inland freshwater ecosystems. Target 15.1 specifically addresses this goal.

The article mentions or implies several indicators that can be used to measure progress towards the identified targets:

1. Indicator 6.3.2: Proportion of bodies of water with good ambient water quality

This indicator can be used to assess the impact of pesticide leaching on water quality in aquifers, rivers, and oceans. It measures the proportion of bodies of water that meet the criteria for good ambient water quality.

2. Indicator 14.1.1: Index of coastal eutrophication and floating plastic debris density

While not directly related to pesticides, this indicator can be used to monitor the overall health of marine ecosystems impacted by pollution, including pesticide contamination. It measures the index of coastal eutrophication and the density of floating plastic debris.

3. Indicator 15.1.1: Forest area as a proportion of total land area

This indicator measures the extent of forest cover as a proportion of the total land area. It indirectly reflects the impact of pesticide contamination on terrestrial ecosystems, as forests play a crucial role in maintaining biodiversity and ecosystem services.

4. Indicator 15.1.2: Proportion of important sites for terrestrial and freshwater biodiversity covered by protected areas

This indicator assesses the extent to which important sites for terrestrial and freshwater biodiversity are covered by protected areas. It reflects efforts to conserve and restore ecosystems affected by pesticide pollution.

Table: SDGs, Targets, and Indicators

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Source: earth.com

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