The Role of Agriculture in Arsenic Water Contamination
- Published:
- Updated: January 6, 2025
Summary
Agriculture significantly contributes to arsenic water contamination through practices like pesticide use, animal feed additives, and irrigation. Arsenic, a naturally occurring element, can leach into water sources, posing health risks. Sustainable farming practices and regulations are crucial for managing arsenic levels and safeguarding water quality.
- Agricultural practices contributing to arsenic contamination
- Health effects of arsenic exposure
- Sustainable farming strategies and regulatory measures
The role of agriculture in the contamination of arsenic water is a tricky, pervasive problem with long-term consequences for human health and the environment. Nature’s naturally occurring element arsenic is deposited in water sources by various farming practices (arsenic pesticides and fertilisers), and through irrigation of polluted water supplies. The way in which agriculture can cause arsenic contamination is important to determine how to approach sustainable farming practices, manage water, and protect water bodies from arsenic contamination.
Understanding Arsenic
The element arsenic is an element that naturally occurs in the crust of Earth and comes in organic as well as inorganic forms. The more dangerous inorganic arsenic is usually thought of as pollution from industry and agriculture. Some arsenic in soil and water is a natural part of the environment, but human activities such as agriculture can massively increase it in the environment.
When it comes to agriculture, arsenic enters the environment via many pathways and leads to the pollution of groundwater – most people’s water source. Knowledge of these pathways is fundamental to developing good approaches to controlling arsenic concentrations in drinking water.
Which agricultural practices are known to contribute to arsenic contamination in soil and water?
Some agriculture can help the mobilization and transport of arsenic from the land to the water. Arsenic-based pesticides and fertilisers, arsenic-containing animal manure on the fields, some forms of irrigation – all can increase arsenic levels in the water.
The arsenic contamination is made worse in places where bedrock is arsenic-rich. Water that soaks into the soil can strip arsenic from rocks and leach it into groundwater. Eventually, this can accumulate arsenic in water bodies very quickly.
Pesticides and Arsenic
Arsenic has always been an important component of many pesticides and herbicides because it controls pests. And even though these products were discontinued in most countries, there is still an inheritance to be made. Previously used arsenic pesticides, if dropped into fields decades ago, remain in the ground and, if strewn or dispersed, can seep into groundwater.
This arsenic legacy of pesticides is an issue for arsenic control going forward. Even when these products aren’t used anymore, they can still contaminate drinking water with arsenic.
Arsenic in Animal Feed
The other agricultural arsenic source is certain forms of animal feed. Others feed additives in poultry and pig production used to be made up of arsenic compounds designed to grow animals, remove parasites and increase pigmentation. Grass from animals who have been given these add-ons may be extremely rich in arsenic.
If used as fertiliser in the fields, this manure can lead to soil arsenic. The rain and irrigation water can then mobilise this arsenic and move it into surface and groundwater.
Irrigation and Arsenic Contamination
Crop irrigation, especially in arsenic-heavy places, can help to mobilise and transport arsenic. When water is pumped into fields, arsenic in the soil will be drawn out and filtered into the groundwater.
Also, when groundwater is ploughed into the ground, this pumping of water can pull arsenic-laden water towards the surface. That can make arsenic concentrations higher in the shallower groundwater sources commonly consumed as drinking water.
Health Effects of Arsenic Exposure
The health risk of arsenic in tap water is very real. Arsenic can cause all sorts of diseases and ailments when long-term exposure occurs, from skin disease and cancers to heart disease and childhood development disorders.
Arsenic in drinking water is a reference level recommended by the World Health Organization (WHO) of 10 g/L. But in most areas, especially in rural areas where groundwater is untreated, arsenic levels can go much higher than this rule.
What are some sustainable agricultural practices that can help reduce arsenic contamination in soil and water?
Changing to more sustainable agriculture can also help reduce arsenic pollution. Some potential measures include:
Abandoning arsenic-based products in animal feed.
Applying tougher restrictions to arsenic-containing manure use and disposal.
Incentivizing non-arsenic pesticide-free farming practices.
Adapted irrigation methods to restrict arsenic mobilization and transportation.
Such measures — in conjunction with regular water quality testing and research on new forms of remediation — can protect our water from arsenic exposure.
Regulations and Guidelines for Arsenic in Agricultural Practices
Due to the health effects of arsenic, a number of policies and guidelines have been developed to control arsenic use in agriculture. Arsenic pesticides, for example, have been prohibited or limited in most countries. In the same vein, animal feeds have been banned in quantities limited to arsenic.
Such policies and rules are essential for preventing arsenic pollution. But that can be hard to enforce, particularly in places where agriculture is not well-regulated. What’s more, such measures mainly tackle new arsenic inputs and don’t entirely eliminate legacy arsenic in the soil.
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