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Huang, C. (2014). Screening organic contaminants in the desert tortoise in the mojave. Unpublished thesis , San Diego State University. 
Added by: Sarina Wunderlich (06 Jul 2014 16:11:41 UTC)
Resource type: Thesis/Dissertation
BibTeX citation key: anon2014i
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Categories: General
Keywords: Ernährung - nutrition, Geoemydidae, Habitat - habitat, Heosemys grandis, Nordamerika - North America, Schildkröten - turtles + tortoises, Toxikologie - toxicology
Creators: Huang
Publisher: San Diego State University
Views: 6/464
Views index: 28%
Popularity index: 7%
URLs     http://sdsu-dspace ... dle/10211.3/115564
Testudinidae Anthropogenic activities such as recreation, agriculture, and transportation are major contributors to environmental contaminants. These contaminants not only affect human health, but can also exert an ecological risk. For example, the Mojave Desert tortoise (Gopherus agassizii) population around the town of Primm is at risk from being exposed to anthropogenic activities. The objectives of the study were to i) examine desert tortoise plasma utilizing a non-targeted analysis method to screen for bio-accumulating organic contaminants, ii) identify sources of pollution in the desert environment that may affect wildlife health, iii) obtain baseline data for future comparison with studies conducted on contamination levels in desert tortoise, and iv) compare the two groups of tortoises sampled to see if there was statistical correlation between contaminant levels and factors such as sex and size of the animal. This study utilized two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCGC/ToF-MS) to screen for the presence of organic contaminants in the threatened Desert tortoise. A non-targeted approach was utilized to examine the tortoise plasma for pollutants. Twenty-six tortoise plasma samples were collected. Due to the fact that the non-targeted analysis is time consuming, among these, four samples were selected from the Silver State (SS) region for non-targeted screening of POPs. As result, four main groups of compounds and a total of 15 compounds were identified. The four main groups were alkylated aromatic rings, partially saturated benzyls, polycyclic aromatic hydrocarbons (PAHs), and other compounds of interest. They can originate from a wide range of sources such as various forms of fuel (petroleum, shale, and coal), and combustion byproducts. Utilizing the official standards, we were able to confirm the presence of 9,10-dihydrophenanthrene, 1,4-bis(1-methylethyl)-benzene, and 1,1-diethylpropyl-benzene in the samples. Some contaminants seem to originate from plants, and are potentially toxic. The sampling area was a native desert environment, which is in close proximity to the town of Primm, solar, and natural gas power plants, Interstate 15, a radioactive settling pond, and gas stations, all capable of contributing to the organic pollutants we have detected in the samples. Statistical analysis suggests that the concentration of 9,10-dihydrophenanthrene was statistically significantly higher in the tortoise plasma collected at SS than SL. This finding warrants further study on the compound and the region. There was a significant correlation between the contaminant concentrations in plasma and the contaminant concentrations in lipid in both regions, implying that these compounds are lipophilic. Furthermore, analysis also displayed a significant correlation between 9,10-dihydrophenanthrene and 1,1-diethylpropyl-benzene suggesting a common pollutant source for both contaminants. Tortoise size and sex were not significant predictors of concentration of the organic pollutants. Statistical analysis also showed a higher concentration of 9,10-dihydrophenanthrene, 1,4-bis(1-methylethyl)-benzene, and 1,1-diethylpropyl-benzene in the SS region. However, only the concentration of 9,10-dihydophenanthrene was statistically significant, the other two compounds had high concentrations but were not statistically significant. Moreover there were also unidentified compounds found in all four samples that were analyzed. The SS region demonstrated that the relative response (RR) was statistically significantly higher at SS than SL in both normalized plasma and lipid content. Although tests demonstrate that there is significant correlation between the RR of the unknown compounds and 9,10-dihydrophenanthrene, further analysis for identification is required.
Added by: Sarina Wunderlich  
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