When I teach about ways to protect our water quality, I use a watershed model. The big plastic tabletop-sized relief map includes a lake, streams, a farm, a factory, a subdivision, a golf course, roads, bridges, sewage treatment plant, etc. — a typical assortment of anthropogenic additions one will find in most developed areas on earth. This model represents a watershed; all the people living and working there share the same drinking water. I use the model to clearly illustrate that everything that everyone does above ground can influence the quality of the water underground.
During the lesson, I call for volunteers. I ask for someone to role-play a farmer, a wealthy polluting industrialist, a greedy land developer, and a road/bridge builder. Then I give each of them a pile of scale-sized accoutrements to live out their newly acquired occupation within the model. The farmer places his barn, tractor, livestock and fencing; tilled ground meets the water’s edge. The industrialist builds his factory; polluted sludge drains into the adjacent stream. The developer puts houses on streetside lots; storm drains run debris directly to the lake. The road builder bulldozes and flattens; soil erodes and oil drips. Once the model pieces are in place, I give little shakers of powders to the volunteers to represent the fertilizers, pesticides and oils that are then liberally applied to the farms, lawns, roadways and golf courses. The thin layer of powder is harmless enough until along comes the big spray bottle to represent a crashing thunderstorm of Florida proportions. The water drops that form on the plastic land turn red and green, quickly making way downhill to the spring fed lake. I pull the plug from the lake bottom and the dyed water, now a muddled mess, drains into a bowl below: the Florida aquifer. My offer of a refreshing cup of the brown sludgy water is unanimously rejected. Imagine that. It’s only kool-aid and cocoa, but in our minds it has become glyphosate, imidacloprid, urea formaldyhede and petroleum residues — pollutants that have destroyed our precious, life-giving water supply.
Water covers almost two-thirds of the earth’s surface, and much of its subsurface, too. Water is a common element that links ecosystems, transporting food, nutrients and organisms. Fresh water — critical for human consumption — is very limited with less than 1% of the planet’s water in lakes, streams, rivers, and groundwater. Fortunately, we do not live on plastic land that allows all runoff to go directly to our drinking water source. But, in spite of the earth’s best efforts at self-defense, many harmful particles and residues do end up as runoff into our local water bodies, and can have a profound effect on the quality of our water.
U.S. Geological Survey (USGS) research has shown that some fungicides are moved from areas of intense use to nearby streams and groundwater at concentrations of concern for environmental health. For instance, the Toxic Substances Hydrology Program study documented the presence of bascalid in groundwater, zoxaminde in sediments and pyraclostrobin in suspended sediments.
Some studies suggest that fungicides may be more toxic to freshwater biological communities, including beneficial fungi, than previously expected. The results of this study indicate the importance of including fungicides in pesticide-monitoring programs, particularly in areas where crops are grown that require frequent treatments to prevent fungal diseases. There are more than 3,600 pesticide products containing fungicides registered with the U.S. Environmental Protection Agency, yet very few studies have investigated fungicide occurrence in the environment. When USGS scientists recently researched this, they found at least one fungicide in 75% of the surface waters sampled and in 58% of the groundwater wells sampled. They also found at least two fungicides in 55% of the bed sediment samples and in 83 percent of the suspended sediment samples that were collected.
|Summary of Fungicides Detected|
|12 fungicides were detected in streams, including|
|Six fungicides were detected in sediments, including:|
Source: USGS Toxic Substances Hydrology Program
The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) defines a pesticide as “any substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest.” This can include plant growth regulators, defoliators and desiccants, and categories of insecticides, fungicides, herbicides, rodenticides and more. The physical properties of pesticides are the factors that influence the fate of pesticides in our environment.
 “Crosscutting Topics: Surface-Water Contaminant Transport,” USGS Toxic Substances Hydrology Program, last modified April 12, 2013, http://toxics.usgs.gov/topics/sw_contamtransport.html.