31
Aug
Synthetic Fertilizers Mobilize Uranium, Contaminating Water
(Beyond Pesticides, August 31, 2015) A study published in Environmental Science and Technology, funded in part by the U.S. Geological Survey (USGS), has found that almost 2 million people are living near aquifer sites contaminated with uranium that is mobilized by human-contributed nitrate. Nitrate is a common groundwater contaminant that is sourced mainly from chemical fertilizers and animal waste. Chronic exposure to elevated levels of uranium can lead to kidney damage and cancer. These findings emphasize the dangers of synthetic fertilizer overuse, and highlight the need to switch to safer alternatives.
The study, “Natural Uranium Contamination in Major U.S. Aquifers Linked to Nitrate,” analyzed approximately 275,000 groundwater samples from the Great Plains regions and California, finding that many residents often live less than a mile from uranium-contaminated wells that exceed guidelines set by the Environmental Protection Agency (EPA). In the High Plains aquifer, researchers find uranium concentrations up to 89 times EPA standards, while the Central Valley aquifer measure up to 180 times EPA standards. The study also reports that 78% of these uranium-contaminated sites are linked with the presence of nitrates. Nitrate mobilizes naturally occurring uranium through a series of reactions that oxidize the material, making it water soluble. This means that the uranium is released into the aquifers due to the interaction with nitrates.
In the High Plains and Central Valley aquifers, nitrate concentrations are 189 and 34 times the EPA standard, respectively. A 2013 study found that the loss of synthetic nitrogen fertilizer in groundwater occurs at low rates over many decades, which means it could take years to reduce nitrate contamination in groundwater, including in aquifers that supply drinking water and irrigation. The High Plains aquifer is the largest in the U.S., providing drinking and irrigation water to eight states, while the Central Valley aquifer is California’s largest, and sits just below the state’s most fertile agricultural lands. Previous studies have shown that food crops can accumulate uranium when irrigated with contaminated water, according to the researchers of this study.
Synthetic fertilizers not only release nitrates, but they also have a tendency to be high in phosphorus, due to the fact that it is a critical nutrient for plant growth and development in synthetic systems that focus on delivering soluble nutrients to the plant while ignoring and harming microbial life in the soil. The synthetic fertilizers are also a major source of non-point pollution in U.S waterways because much of the soluble nitrogen is not taken up by the plant. Non-point pollution occurs as a result of runoff from diffuse sources moving into rivers, lakes, streams, wetlands or groundwater. On the other hand, organic soil fertility methods deliver insoluble nutrient nitrogen through the work of soil organisms that release the nitrogen at about the rate that they are used by the plant. Similarly, soil high in organic matter produces phosphorus that is stable in the soil and taken up by the plant.
High phosphorus loads increase water turbidity, spur toxic algae blooms, and decrease light penetration. Once algae dies off, aerobic bacteria consume the dead algae, resulting in dangerously low oxygen levels, which further decreases biodiversity and can stress or even kill aquatic wildlife. The residential use of lawn fertilizers is responsible for a significant amount of the non-point pollution of nitrate and phosphorus. Legislative efforts to reduce this harmful runoff have fallen short, although states are increasingly adopting measures that restrict the application of high levels of phosphorus.
While organic turf and lawn management nurtures natural sources of soil nutrients and reduces hazardous runoff, the chemical industry repeatedly claims that the source (whether organic or synthetic) of nutrients in a fertilizer is irrelevant. However, because of the harm they cause to soil life and the environment, synthetic fertilizers are prohibited in certified organic systems under the national Organic Foods Production Act (OFPA).
What Can You Do?
Preventing soil erosion and preforming soil tests should be a focal point for concerned citizens working to stop nitrate and phosphorus pollution. In this context, the source of a fertilizer is extremely relevant to these efforts. While organic production methods build a lawn’s capacity to hold soil, synthetic systems weaken this ability. From a holistic soil management perspective, organic management yields the optimum environmental safeguards, while nurturing healthy plants. The goal of an organic production system, whether in agriculture or turf management, is to feed the soil by utilizing methods that build organic matter and encourage microbial diversity. This is achieved through cultural practices, such as mowing, aeration, irrigation, and over-seeding, without the use of synthetic inputs, including chemical fertilizers, insecticides, herbicides, or fungicides.
There are a few simple steps that can make a difference in preventing non-point source pollution and subsequent harm to waterways, the environment, and the public’s health:
- Prevent Soil Erosion — Preventing soil erosion keeps phosphorus from entering local rivers, lakes, and streams. Mulch bare soil with straw or wood chips, and edge your yard with native trees and shrubs to prevent the loss of topsoil. Also, be careful not to over-water your lawn.
- Keep fertilizer, leaves, and grass clippings off of impermeable surfaces and on your lawn — When left on impermeable surfaces, these materials have a greater chance of running off into local waterways where they degrade and contribute to excessive nutrient loads.
- Keep fertilizers away from ponds, rivers, lakes, and streams — Be careful when applying fertilizers near water. Create a buffer of at least 25 ft. in order to minimize runoff. Additionally, keep an eye on the weather forecast in order to prevent applying fertilizer before a heavy downpour, as heavy rain can cause recently applied fertilizers to runoff before being incorporated into the soil.
- Maintain a healthy organic lawn — By maintaining a healthy lawn through proper care, you can cut down on your overall fertilizer needs. Beyond Pesticides Lawns and Landscapes webpage has all the information you need to maintain a healthy lawn.
Clean water is essential for human health, wildlife, and a balanced environment. Check out Beyond Pesticides’ Threatened Waters webpage for more information.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: phys.org
Photo Source: phys.org
