The Effects of Atrazine Application to the Environment The Effects of Atrazine Application to the Environment. By: Perry Loken, Tim Weisbrod, Nick Taylor, Sara Schmidt

What is Atrazine? Atrazine is a 6-carbon S-chlorotriazine. Atrazine is the most widely used S-triazine. Other S-triazines used as herbicides are Symazine and cyromazine. Atrazine is not very volatile, reactive or flammable but dissolves readily in water. -atrazine is a 6-carbon S-chlorotriazine -Pure atrazine is a man-made odorless white powder that is not naturally occurring, it is used in a powder, liquid and granular form. -Atrazine has been known to persist in soil and water long after application has ended Bio-degradation is theoretically possible but studies have found that atrazine is still persistant in the environment. Atrazine has been seen to Bio-accumulate in Zebra fish embryo’s with a BCF of 19

How Atrazine is released into the environment. Atrazine is a selective herbicide used primarily in the agriculture industry Atrazine is primarily applied to corn, sorghum and sugar cane. Atrazine is a Restricted Use Pesticide (RUP). -Atrazine is a selective herbicide used primarily as a broadleaf weed and grass controller in many agricultural settings. -Atrazine is usually applied in the spring or summer months because in order to be activated atrazine must be dissolved in water and enter the target plants root system. -this causes problems because of the large amount of rain in the spring which can make it mobile and wash it into another median. -Atrazine is a restricted use pesticide(rup) this means that in order to use atrazine a farmer must go through a yearly certification process where that person is liscenced by the state.

Amounts of Atrazine released into the environment. In 1993 the total amount of atrazine used in the whole country was 35,000 tons. Atrazine usage have been increasing steadily since the 1960’s to the current level of 70,000-90,000 tons per year. Environmental levels of atrazine in countries that use it average 5ug/L -In small agricultural ponds with intense run-off can obtain levels of 1mg/L

Map of Atrazine application by agriculture in the U.S.

How Atrazine Works Atrazine was designed to block photosynthesis. Crop plants are able to detoxify the atrazine. Atrazine works well as both a pre- and post emergent herbicide. -Atrazine was designed to reduce the CO2 fixation in selected plants by blocking photosynthesis. -Crop plants aren’t effected when they are induced with Glutathione S-transferences (GST) which is one mechanism for detoxifying the Atrazine that is in contact with the plants by breaking it down before it can disrupt photosynthesis. Atrazine works well as both a pre- and post emergent herbicide- due to its ability to block photosynthesis when in contact with non crop plants.

Why Atrazine may be a threat to the environment The complete effects of Atrazine’s ability to block normal functions of plants and animals (expecially humans) is unknown. Atrazine is being found in surface and drinking water reserves in areas of atrazine use It takes considerable time to biodegrade out of the an aqueous system. Because of our extensive reliance on herbicides. -The complete effects of Atrazine’s ability to block normal functions of plants and animals (expecially humans) is unknown due to a lack of data on humans because of obvious morality issues that would be involved in such a study. Atrazine is being found in surface and drinking water reserves in areas of atrazine use It takes considerable time to biodegrade out of the an aqueous system this is due to diverse conditions that are present in the system . Because of our extensive reliance on herbicides such as Atrazine in order to continue to produce enough food to support our planet going to need to find better more biodegradable pesticides or we will have to cut back on our use of the currently used ones such as atrazine.

Outline of Atrazine’s course through the environment -Because of the application techniques of spraying herbicides broadly on the fields over the soil the first thing affected is the soil -From here it can be evaporated into the air or stay in the plants washed into the surface water

Atrazine in the soil Degradation effects of Atrazine while it is in the soil. Microbial degradation is the principle mechanism. The kinetics is based on the nitrogen avalibility in the soil.

Application history Two types of fields Adapted Non-adapted Has had atrazine applied on a consistent basis. Non-adapted Has not had atrazine applied to the soil. Adapted soils have a higher degradation rate due to a higher microbial population. Almost like the atrazine is feeding the microbial and causing the population to grow. Dealkylation dehalogenation. Non-adapted soils has a lower degradtion rate. Lower microbial population.

Nitrogen rich soils Nitrogen rich soils contain nitrogen molecules that are easier for the microbial to break down. So Atrazine will be less likely attacked. If nitrogen is deficient, then Atrazine would be a source of nitrogen for the microbial. Addition of organic amendments stimulates the microbial biomass, accelerates biodegradation.

Movement through the soil Clay and silty soil Movement is limited to soil layers of minimal depth. Sandy soil movement reaches depths greater than clay and silty soil.

Atrazine in the air Highest Concentration is in Summer, Lowest Concentration is in Winter Remains in the air more in enclosed areas

Atrazine run-off to surface water In the spring Atrazine levels are highest. Most of the Atrazine in the soil eventually runs off into surface water. Once in surface water it can be transported long distances before it has time to degrade. In the spring Atrazine levels are highest. -most of the atrazine applied to kill pre-emergent plants ends up as run-off in local surface water. Most of the Atrazine in the soil eventually runs off into surface water -Once in surface water it can be transported long distances before it has time to degrade. once in surface water it degrades very slowly it can have a half life of >200 days. -though atrazine does biodegrade slow in water sources there is a possibility for special bacteria to be grown that survive off of atrazine as their only energy source. But unfortunately the natural systems are far more complex and at the present time such solutions are unrealistic.

Atrazine’s effect on animals Once in surface water, atrazine is in direct contact with many species which drink or live in the water. Atrazine does not bioaccumulate up the food chain. The major effects of atrazine on animals are: Endocrine/Reproductive effects and Neurological effects Once in surface water, atrazine is in direct contact with many species which drink or live in the water. Atrazine does not bioaccumulate up the food chain. The major effects of atrazine on animals are: Endocrine effects, Neurological effects and reproductive effects.

Endocrine and Reproductive Effects Atrazine disrupts pregnancy by inhibiting normal ovulatory surges. Which include a release in luteinizing hormone (LH), Prolactin (PRL) and testosterone (in males). Also atrazine has been known to cause detoxification problems. -Atrazine disrupts pregnancy by inhibiting normal ovulatory surges .-Which include a release in luteinizing hormone (LH) and Prolactin (PRL) and testosterone(in males). Inhibiting the release of (LH) with 30-50mg/kg of atrazine causes the pregnancy to be terminated. Inhibiting the release of (PRL) causes the cancerous mammary gland tumors. Inhibitng the release of testosterone can slow down the normal development of the reproductive track. In zebra fish embryos the process of detoxifying the atrazine can use up the available yolk and harm the fish’s development.

Nerveous system problems Atrazine effects the Purkije cells of the nerveous system. Cellular activity is lowered by 50% in 60 minutes. The exact mechanism of this is unknown. Atrazine causes motor disorders in animals. Atrazine effects the Purkije cells of the nerveous system. Cellular activity is lowered by 50% in 60 minutes. The exact mechanism of this is unknown. Atrazine causes motor disorders in animals.

Human Exposure 2-3 million people are exposed 0.2 ppb exposed to in drinking water Minimal amounts from food

Chemical Affects Atrazine has aromatic activities Estrogen levels reduce Underlying reason for hormonal disruption and tumor promoting properties

The Future Womb Exposure Suffer permanent brain defects Breast Feeding Exposure

Children Sonora, Mexico Compared preschoolers that were exposed to Atrazine to the students that were not. Differences is: Hand-eye coordination Metal and Physical skills

Long Term Exposure Increase Risk of Ovarian Cancer Increase Risk of Breast Cancer Increase Infertility Increase Reproductive Disorder

Modeling with Stella Model Logic Method to find Atrazine sink Predict environmental degradation Compare soil, Air, Water degradation Interpretation of Stella

Model

Atrazine In Soil Outflows Inflows Biological Degradation, Half-life 42.5 days Erosion, 55% immediately lost Evaporation, Half-life 97 days Inflows Application of 34 million kg Condensation from Air

Atrazine In Air Inflows Outflows Evaporation, Half Life 97 days initial applicationspraying Outflows Oxidation, Half life 0.11 Days Photodegradation, Half life 0.796 days Condensation Take into account 30% of Earth land

Atrazine In Water Inflows Outflows Erosion, 55% Condensation, F(x) of Air Outflows Sedimentation, Half life 14 days Aquatic Degradation, Half life 3.2 days Ingestion

Atrazine Movement

Water as the Sink Air is not:Degradation less than 1 day Soil, initially a sink, long run NO The Data suggest that water is the sink the sink is draining, does not acumulate Warning: decrease with one application after years steady increase

Degradation Routes Air initial spike degrades quickly Water Spikes later and degrades slower Soil initial spike but degrades out

Future Projection Projected to 2020 It can be seen that it would take until 2012 or 22 years to be nearly rid of Atrazine Indicates steadily rising levels of ATR over time with yearly application

Demonstration Atrazine Movement Through the Environment Begins with application, mainly crops

Stella Agreement Stella agrees with the literature in that atrazine does not persist relatively long in the environment Stella is also in agreement in terms of water being the final sink.

Demonstration It then works its way to the water supply, by runoff and other mechaisms then it follows tributaries and streams Ends up in Large rivers, Lakes and Oceans

Conclusions Banning atrazine would decrease the environmental problem but could increase health and environmental risks. Corn and Sorghum crop yields would be reduced. The banning would increase the use of atrazine alternatives, which are less well understood. A better plan might be to find alternative methods of crop management in order to get the best yeilds with the smallest amount of pesticides.

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