Phytoremediation Essays - Soil Contamination, Ecological Restoration

Phytoremediation Essays - Soil Contamination, Ecological Restoration Phytoremediation Introduction: In recent years it has become clear that some environmental chemicals can cause risks to the developing embryo and fetus. Evaluating the developmental toxicity of environmental chemicals is now a prominent public health concern. The suspected association between TCE and congenital cardiac malformations warrants special attention because TCE is a common drinking water contaminant that is detected in water supplies throughout the U.S. and the world. There is a lot of concern about the clean up of toxic pollutants from the environment. Traditional methods for cleaning up contaminated sites such as dig and haul, pump and treat, soil venting, air sparging and others are generally harmful to habitats. Some methods strip the soil of vital nutrients and microorganisms, so nothing can grow on the site, even if it has been decontaminated. Typically these mechanical methods are also very expensive. Most of the remediation technologies that are currently in use are very expensive, relatively inefficient and generate a lot of waste, to be disposed of. Cleaning up contamination: Phytoremediation is a novel, efficient, environmentally friendly, low-cost technology, which uses plants and trees to clean up soil and water contaminated with heavy metals and/or organic contaminants such as solvents, crude oil, polyaromatic hydrocarbons and other toxic compounds from contaminated environments. This technology is useful for soil and water remediation. Mechanisms: Phytoremediation uses one basic concept: the plant takes the pollutant through the roots. The pollutant can be stored in the plant (phytoextraction), volatized by the plant (phytovolatization), metabolized by the plant (phytodegradation), or any combination of the above. Phytoextraction is the uptake and storage of pollutants in the plants stem or leaves. Some plants, called hyperaccumulators, draw pollutants through the roots. After the pollutants accumulate in the stem and leaves the plants are harvested. Then plants can be either burned or sold. Even if the plants cannot be used, incineration and disposal of the plants is still cheaper than traditional remediation methods. As a comparison, it is estimated a site containing 5000 tons of contaminated soil will produce only 20-30 tons of ash (Black, 1995). This method is particularly useful when remediating metals. Some metals are also being recycled from the ash. Phytovolatization is the uptake and vaporization of pollutants by a plant. This mechanism takes a solid or liquid contaminant and transforms it to an airborne vapor. The vapor can either be the pure pollutant, or the plant can metabolize the pollutant before it is vaporized, as in the case of mercury, lead and selenium (Boyajian and Carriera, 1997; Black, 1995; Wantanbe, 1997). Phytodegradation is plants metabolizing pollutants. After the contaminant has been drawn into the plant, it assimilates into plant tissue, where the plant then degrades the pollutant. This metabolization by plant-derived enzymes such as nitrosedictase, laccase, dehalogenase, and nitrilase assimilates into plant tissue, where the plant then degrades the pollutant. This metabolization by plant-derived enzymes such as nitroredictase, laccase, dehalogenase, and nitrilase, has yet to be fully documented, but has been demonstrated in field studies (Boyajian and Carriera, 1997). The daughter compounds can be either volatized or stored in the plant. If the daughter compounds are relatively benign, the plants can still be used in traditional applications. The most effective current phytoremediation sites in practice combine these three mechanisms to clean up a site. For example, poplar trees can accumulate, degrade and volatize the pollutants in the remediation of organics. Techniques: Phytoremediation is more than just planting and letting the foliage grow; the site must be engineered to prevent erosion and flooding and maximize pollutant uptake. There are 3 main planting techniques for phytoremediation. 1.Growing plants on the land, like crops. This technique is most useful when the contaminant is within the plant root zone, typically 3 - 6 feet (Ecological Engineering, 1997), or the tree root zone, typically 10-15 feet. 2.Growing plants in water (aquaculture). Water from deeper aquifers can be pumped out of the ground and circulated through a reactor of plants and then used in an application where it is returned to the earth (e.g. irrigation) 3.Growing trees on the land and constructing wells through which tree roots can grow. This method can remediate deeper aquifers in-situ. The wells provide an artery for tree roots to grow toward the water and form

How to Make and Use Homemade Ant Bait Traps

How to Make and Use Homemade Ant Bait Traps To get rid of ants for good, you need to use a treatment that kills the entire colony, including the queen back in the nest. Dont waste your time squishing the ants on your counters because as long as the colony is actively nesting nearby, more ants will appear. Ant baits, whether homemade or commercial, are the treatment of choice for eliminating kitchen infestations. Ant-killing bait combines a desirable ant food with a pesticide. Worker ants carry the food back to the nest, where the pesticide works on the entire colony. You can make an effective ant killer using boric acid, a low toxicity pesticide available in hardware stores and pharmacies. Identify the Ants Before you make and use homemade ant bait, youll need to confirm which type of ants you have. Ants that youd find in your kitchen usually fall into one of two groups: sugar ants or grease ants.   From an entomological perspective, theres really no such thing as sugar ants. People use the term sugar ants to describe any number of ants that happen to like sweets. Depending on where you live, your sugar ants may actually be Argentine ants, odorous house ants, pavement ants, or some other kind of ants. Grease ants, also referred to as protein-loving ants, prefer proteins or fats over sugars. This doesnt mean they wont eat sweets, but theyre more interested in food with some protein content in it. Grease ants include little black ants, big-headed ants, and pavement ants, among others. To determine which kind of ants you have, do a taste test. Put a teaspoon of jelly and a teaspoon of peanut butter  in the area where you see the most ant traffic. Tape down a piece of waxed paper, or use a paper plate, and apply the bait on the paper or plate to avoid smearing jelly or peanut butter onto your counters or floor. Next, determine which type of baits the ants prefer. If they went for jelly, make a sugar ant bait. Ants that prefer peanut butter will respond to a protein-based bait. Now youre ready to make your homemade ant bait. Ingredients: Break Out the Borax Whether you have sugar or grease ants, boric acid is an effective, minimally toxic pesticide that you can use to create effective ant-killing bate. Both boric acid and sodium borate salts are derived from the element boron, which occurs naturally in soil, water, and rocks. Boric acid is a low-toxicity pesticide, but that does not mean its nontoxic. Virtually any substance can be harmful or fatal if used improperly. Read the label carefully, and follow any directions or cautionary information on the boric acid package. You can purchase boric acid at your local pharmacy or hardware store. Its commonly used as an antiseptic or mixed with water for use as an eyewash. To create a homemade ant killer, youll need to purchase borax in a powder or granule form. How to Make Homemade Ant Killer Use either of the following methods, depending on what kind of ants you have: Sugar ant bait recipe:  Mix 2 tablespoons of mint jelly with about  ¼ teaspoon of boric acid powder. Research suggests that mint jelly is the best sugar ant lure, but you can also try another jelly flavor if you dont have mint jelly in your fridge. Grease ant bait recipe:  Mix 2 tablespoons of peanut butter, 2 tablespoons of honey, and about  ½ teaspoon of boric acid powder. Protein-loving ants respond best to a bait made of both protein and sugar. Use and Application Place your ant bait in an area where you see ants the most. You want the bait to be somewhere along their regular travel path. Use masking tape to secure a square of waxed paper or cardboard, and place the ant-killing mixture on it. If you chose a good location and prepared the right kind of bait, youll probably find ants swarming around the bait within a few hours. If you dont, try moving the bait to a different location. How It Works Boric acid works primarily as a stomach toxin on ants. The worker ants will carry the bait food, loaded with boric acid, back to the nest. There, the ants in the colony will ingest it and die. The boric acid seems to interfere with the ants metabolism, although scientists arent exactly sure how it does so. Sodium borate salts affect an insects exoskeleton, causing the insect to desiccate. Tips and Warnings Keep children and pets away from the ant bait mixture. Although boric acid has low toxicity, you dont want your dog or cat licking up the bait, nor should you allow children to come in contact with it. Store the boric acid and any extra bait mixture where children and pets cannot access it. You will need to replace the bait regularly with a fresh batch, as the ants wont be interested in jelly or peanut butter once it dries up. Continue putting out bait until you no longer see ants. Sources Ant Baits: A Least Toxic Control, University of Nebraska-Lincoln, accessed May 1, 2012Boric Acid (Technical Fact Sheet), National Pesticide Information CenterMaking Your Own Ant Bait, Michigan State University Extension (General Fact Sheet)Boric Acid, National Pesticide Information Center (PDF)Sugar Ants, Washington State University Extension