Download Arsenic Content in the Soil of Waco Wetlands

Arsenic Content in the Soil of Waco Wetlands
Arusha Manasia, Emily Scannapieco, Tony Nguyen Biology 1406-­‐01, Spring 2011, Baylor University Waco, TX 76798 Results In Graph 3, the graphs show an inverse relaJonship. Amount of Arsenic Without Plants Amount of Arsenic With Plants 70 70 60 60 50 50 Units of Arsenic Units of Arsenic Abstract Arsenic is naturally found in wetlands soil due to natural acJviJes such as rock erosion and forest fires. We wanted to test the affect of plants on the quanJty of arsenic in the soil throughout the Waco Wetlands. We hypothesized that cell one would have the highest levels, while cell five would have the lowest. We collected 20 samples, and using a revised procedure from our arsenic kit we produced comparable results of arsenic levels within each cell, both by and away from plants. The arsenic levels in the wetlands showed a U-­‐shape, with cell one and five having the highest levels and cell three having the lowest. 40 30 20 10 Introduc.on 30 20 10 0 0 Cell One Cell Two Cell Three Cell Four Cell Five With Plants 1 Cell One Cell Two Cell Three Cell Four Cell Five With Plants 2 Without Plants 1 Average Amount of Arsenic 70 60 50 40 Average Without Plants 30 Average Plants 20 10 0 Cell One Cell Two Cell Three Cell Four Cell Five The North Bosque River water flows through the wetlands, which has a series of five cells that the water flows through before reentering the river. For the experiment, four different soil samples of approximately 3 grams were taken from each cell. In each cell, two of the samples were within six inches of plants, called “with plant” samples, and two samples were taken a meter away from all plants, called “without plant” samples. The kit used for tesJng the arsenic in the soil was The Quick Rapid Arsenic Test Kit (No. 481396). The non-­‐digesJve method was used as the arsenic soil screening procedure. Due to iniJal low arsenic readings, the procedure was modified to concentrate the amount of arsenic that was tested. Although the results do not actual arsenic units, it does act as a comparison of arsenic levels between cells. Discussion & Conclusion Based on the results, the hypothesis has been rejected. Although the hypothesis was rejected, there sJll seems to be an inverse relaJonship in arsenic levels between with and without plants. Graph 3 shows the average of arsenic content. The red line shows a U-­‐shape of the soil collected with plants and the blue line show an upside down U shape of the data that had the soil without plants. Some causes of that may have been the release of arsenic ader the death of plants, or microbial acJvity. In cell three, the arsenic levels with and without plants are extremely different. The without plants soil sample that was taken from cell 3, though not in the vicinity of live plants, had many dead caeails around it. When those caeails died, they may have released back into the soil any arsenic that was absorbed, which could have increased the arsenic level in cell three. As environment condiJons change in the wetlands, the speciaJon and mobility of arsenic is bound to change, as well as other things. The results that were obtained could change if the wetlands were drained again. For instance, in the presence of vegetaJon and increasing soil organic maeer, microbial acJvity is enhanced, which may have a great impact on the cycling of elements (Turpeinen et al. 1999). Microbes are aeributable to many reacJons that result in changes in speciaJon of arsenic (Turpeinen et al. 1999). Because of these microbes, the levels of arsenic could be constantly shiding through the wetlands. If there are more microbes in cell three, then the levels of arsenic would have increased compared to the other cell. Acknowledgements Marty L. Harvill, Ph.D.; Baylor University Biology Department; Baylor University Dean of Arts & Science; Ms. Nora Schell; Lake Waco Wetlands; URSA; Jade Webb; and Ellie Powell Graph 3 Methods & Materials Without Plants 2 Graph 2 Graph 1 Units of Arsenic Arsenic is a naturally occurring element in the earth’s crust (Habeck 1996-­‐2010). The concentraJon of arsenic in soil varies widely, generally raging from about 1 to 40 parts of arsenic to a million part of soil with an average level of 3 to 4 ppm (Habeck 1996-­‐2010). From runoff and leaching, Arsenic accumulates in the wetlands soil and water. In Figure 1, the Lake Waco Wetlands is made up of small interconnected bodies of water called cells, which water flows through. For the experiment, the amount of arsenic was tested in the soils of each cell, both with and without plants. The hypothesis was that cell one would have higher arsenic levels in comparison to cell five, both with and without plants. 40 Cell: 1 Cell: 2
Cell: 3
Cell: 4
Figure 1 Cell: 5
Literature Cited Carbonell, A., M. Aarabi, R. Delaune, R. Gambrell, and W. Patrickjr. "Arsenic in Wetland VegetaJon: Availability, Phytotoxicity, Uptake and Effects on Plant Growth and NutriJon." The Science of The Total Environment 217.3 (1998): 189-­‐99. Print. Duxbury, John M., Rafiqul M. Islam, M. Jahiruddin, M. Asaduzzaman Khan, Richard H. Loeppert, and G. M. Panaullah. "AccumulaJon of arsenic in soil and rice under wetland condiJon in Bangladesh." Plant & Soil 333.1/2 (2010): 263-­‐274. Academic Search Complete. EBSCO. Web. 3 May 2011. Habeck, Michael. "Arsenic." Eco-­‐USA. Agency for Toxic Substances and Disease Registry, 1996-­‐2010. Web. 03 May 2011. <hep://www.eco-­‐ usa.net/toxics/chemicals/arsenic.shtml> Turpeinen, R., M. Pantsarkallio, M. Haggblom, and T. Kairesalo. "Influence of Microbes on the MobilizaJon, Toxicity and Environment 236.1-­‐3 (1999): 173-­‐80. Print.