Applying Instrumental Neutron Activation Analysis (INAA) to the Study of Toxic Elements in Cotton Seeds

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USDA Final Bulletin

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Cotton has been an important cash crop in the Palmetto State since revolutionary times to the current day. Its seeds are about 15% of the value of the crop and used widely in making oil and feeding animals. Throughout the growing season, cotton assimilates numerous trace elements from the soil, including the toxic ones. Some of these trace elements are accumulated or enriched in cotton seeds. Therefore, cotton seeds can serve as an indicator of heavy metal contamination of local soil. South Carolina, like other states, is subject to the environmental impact of human behaviors. Dozens of heavily-polluted superfund sites are scattered in the state, and most of them are on the National Priority List (NPL) of EPA. Some NPL sites are close to local cotton plantations. It is conceivable that cotton may be under a contamination impact of these sites through ground water movement or other migration paths.We propose to study the cotton seeds and corresponding local soil with a radioanalytical method--Instrumental Neutron Activation Analysis (INAA). INAA has been a versatile tool in multi-element analysis for more than half a century, but it was seldom applied to studying agricultural products especially cash crops. After irradiation of the samples with nuclear reactors, qualitative and quantitative information of the elements can be obtained from the decay spectra recorded by gamma ray spectrometers. By analyzing cotton seeds and the corresponding local soil with INAA, it is possible to determine the level of elements with high accuracy and extreme sensitivity, as well as establish a relationship between the amount of toxic trace elements in the cotton seeds and the level of heavy metal contamination in the local soil.This study is the initial stage of a long-term project. It will concentrate on the Midlands and Low Country of South Carolina, particularly in Aiken, Charleston, and Lexington Counties. The cotton plantations near the NPL sites will be given special attention. Hundreds of cotton seed samples will be collected from local gins, and their corresponding local soil will be gathered, as well. All samples will be irradiated by thermal neutrons from PULSTAR reactor. Both short-lived isotopes and long-lived isotope spectra will be measured after irradiation. Our initial focus will be on concentrations of heavy metals, such as Cd, Zn, Hg, As, etc. In order to deal with the extensive data of nuclear spectra, an online spectra analysis program will be designed and implemented. Neutron flux of the PULSTAR reactor will be simulated with both GEANT4 and MCNPX to mimic the real situation in thermal neutron irradiation.This study will support the mission of the natural resource management program in 1890 Research and train highly- skilled, competent, and well-prepared students in the fields of Nuclear Engineering and Radiochemistry. The immediate outcome of the project is a detailed survey map of toxic elements level in cotton seeds and local soil in South Carolina (initially in the Midlands and Low Country), which will give the public a better understanding of the environmental impact of human activities on traditional cash crops and food industry. Pertinent information from the research will be disseminated to local farmers through 1890 Extension, particularly to those classified as small-limited, resource farmers. This project will make a contribution to enhance the cotton productivity, environmental quality of plantations, food quality and safety, and to improve the economic vitality of rural communities in South Carolina.South Carolina State University (SCSU) is an 1890 land-grant, senior comprehensive institution. This project is conducted by its Nuclear Engineering Program, the only ABET accredited undergraduate Nuclear Engineering program in South Carolina and at an HBCU.


Cotton seeds; Soil; Instrumental neutron activation analysis; INAA; Toxic trace elements; Heavy metal contamination


Agricultural Science | Life Sciences | Plant Sciences



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