This paper examines the environmental consequences of chemical fertilizer use on aquatic ecosystems. Beginning with an overview of how water systems naturally purify themselves and the conditions under which that capacity breaks down, the paper identifies the primary chemical components of modern fertilizers — nitrogen, phosphorus, and potassium — and traces their pathways into rivers, lakes, and oceans. Drawing on data regarding annual fixed-nitrogen releases, the analysis addresses phenomena such as Florida red tide, acid-driven aluminum toxicity, and the broader disruption of aquatic biodiversity. The paper concludes by projecting future trends in fertilizer use and calling for sustainable agricultural alternatives to protect the world's finite water supplies.
Following World War II, innovations in fertilizer production resulted in an explosion in their use. To date, chemical fertilizers have been credited with saving millions of people around the world from starvation, but the accumulated impact of their continued use on aquatic life in surrounding areas has become a source of increasing concern within the scientific community. Because the world's water supplies are finite, it is important to recognize and act on these potential threats before it is too late.
This paper provides an overview of water systems and how they function, followed by a discussion of the different types of chemical fertilizers in use today. An analysis of the impact of chemical fertilizers on aquatic life is followed by an assessment of current and future trends in chemical fertilizer use and their effect on the world's water systems and aquatic life. A summary of the research and key findings is presented in the conclusion.
Ordinarily, water systems are naturally self-cleansing, using oxygen to break down organic pollutants that enter them into benign or inoffensive forms. However, when too much of any type of waste enters a water system, the natural purification processes are diminished and the water becomes unsuitable for a variety of human needs (Henning & Mangun 251). Today, waterborne sewage is comprised primarily of various types of wastes, heavy metals, and toxic substances such as pesticides and chemical fertilizers; the major pollution sources are municipalities, industries, and agriculture, especially hog farms (Henning & Mangun 251).
The quality of water systems is determined by the degree to which bodies of water are able to support aquatic life while also meeting standards for the protection of human health. This level of contamination is determined by establishing baseline standards against which the periodic relative quality of each individual water system is measured (Henning & Mangun 251). Attempts to maintain or restore water quality in these systems are developed according to the amounts and kinds of material discharged into the waterways; the quality of water in streams, rivers, lakes, and oceans therefore depends on the capacity of each water system to cleanse itself of various pollutants. According to Henning and Mangun, this ability depends on the types and amounts of the pollutants as well as on water temperatures, rate of water flow, degree of sedimentation, and mineral content (251). The mineral content of pollutants containing chemical fertilizers already accounts for the lion's share of the nitrogen being released into the world's water systems, but there are other elements involved in modern chemical fertilizers as well, as discussed below.
Modern chemical fertilizers are typically formulated from a combination of one or more of three basic elements: (a) nitrogen, (b) phosphorus, and (c) potassium. Many such fertilizers also contain secondary ingredients in the form of sulfur, magnesium, and calcium ("Fertilizer" 2006). Chemical fertilizers account for an increasingly large share of the total pollutants being discharged into the world's water systems.
Inexpensive methods for synthesizing ammonia were identified after World War II, resulting in the mass production of artificial fertilizer in what the ecologist and nitrogen expert David Tilman has termed "the 35 most glorious years of agricultural production" (quoted in Nierenberg 30). Farmers in industrialized countries as well as those in developing countries now have access to inexpensive and almost limitless quantities of chemical fertilizers. Because these products are cheap, however, much of the material is wasted: "Fertilizer is often very inefficiently applied; much of it never reaches the crop. It leaches out of the fields and into the streams, or it's converted into a nitrogenous gas like nitrous oxide and escapes into the atmosphere" (Nierenberg 30). The impact of these increasing discharges of chemical fertilizers into the world's water systems is examined further below.
"Nitrogen pollution, red tide, and acid toxicity"
"Projected nitrogen discharge increases through 2020"
The research showed that chemical fertilizers represent a dual-edged sword for the sustainability of the world's population. On the one hand, their use has allowed farmers in industrialized nations — and increasingly, farmers in developing nations — to achieve greater crop yields through more intensive agriculture. On the other hand, the continuing use of chemical fertilizers threatens the world's finite water systems through a wide range of chemical interactions, many of which endanger human and animal life alike.
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