Matching Items (4)
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- All Subjects: Pollution
- All Subjects: water treatment
- Creators: Halden, Rolf
Description
Microplastics are defined as small pieces of plastics that are less than five millimeters in size. These microplastics can vary in their appearance, are known to be harmful to aquatic life and can threaten life cycles of marine organisms because of their chemical make-up and the toxic additives used in their manufacture. Although small in size, it is hypothesized that microplastics can serve as an example of how human activities can alter ecosystems near and far. To investigate the implications and determine the potential impact of microplastics on a protected atoll’s ecosystems, red-footed booby (Sula sula) guano samples from six locations on Palmyra Atoll were acquired from North Carolina State University via The Nature Conservancy and were inspected for the presence of microplastics. Each of the guano samples were weighed and prepared via wet oxidation. Microplastic fibers were detected via stereoscope microscopy and analyzed for chemical composition via Raman spectroscopy. All six sampling locations within Palmyra Atoll contained microplastic fibers identified as polyethylene terephthalate, with North-South Causeway and Eastern Island having the highest average number of microplastic fibers found per gram of guano sample (n = 0.611). These data provide evidence that seabirds can serve as vectors for the spread of microplastic pollution. This research lends context to the widespread impact of plastic pollution and states possible implications of its presence in delicate ecosystems.
ContributorsAnderson, Alyssa Cerise (Author) / Lisenbee, Cayle (Thesis director) / Halden, Rolf (Committee member) / Rolsky, Charles (Committee member) / College of Health Solutions (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Heavy metals and persistent organic pollutants contribute to human health risks worldwide. Among the most common routes of exposure to pollutants for humans are through the consumption of contaminated water and food, with fish being among the greatest vectors for ingestion of heavy metals in humans, particularly mercury.This dissertation consists of three chapters with a central theme of investigating heavy metal and persistent organic pollutant concentrations in fish and corned beef, which are two commonly consumed food items in American Samoa. A literature review illustrated that historically the primary pollutants of concern in fish muscle tissue from American Samoa have been mercury, arsenic, and polycyclic aromatic hydrocarbon mixtures. To better understand the changes in heavy metals and persistent organic pollutants in fish, this study reports an updated data set, comparing concentrations in pollutants as they have changed over time. To further investigate pollutants in fish tissue, 77 locally caught and commonly consumed fish were analyzed for heavy metals and persistent organic pollutants, and baseline human health risk assessments were calculated for contaminants that had available oral reference doses. While in American Samoa collecting fish for contaminant analyses, it was realized that canned corned beef appeared to be more commonly consumed than fresh fish. An IRB approved consumption survey revealed that 89% of American Samoan adults regularly consume fish, which is the same percentage of people that reported eating canned corned beef, indicating a dramatic increase in this food item to their diet since its introduction in the 20th century.
Results of this study indicate that fish muscle tissue generally has higher heavy metal concentrations than canned corned beef, and that mercury continues to be a main contaminant of concern when consuming fresh and canned fish in American Samoa. While none of the heavy metal concentrations in corned beef exceeded calculated action levels, these foods might contribute to negative health outcomes in other ways. One of the main findings of this study is that either the presence or the ability to detect persistent organic pollutant concentrations are increasing in fish tissue and should be periodically monitored to adequately reflect current conditions.
ContributorsLewis, Tiffany Beth (Author) / Polidoro, Beth (Thesis advisor) / Neuer, Susanne (Thesis advisor) / Halden, Rolf (Committee member) / Schoon, Michael (Committee member) / Arizona State University (Publisher)
Created2023
Description
Arsenic (As) and chromium (Cr) occur naturally in AZ surface and groundwaters, pose different health impacts, and exhibit different treatment efficacies. Hexavalent chromium (Cr(VI)) has newly recognized human health concerns, and State and Federal agencies are evaluating a low Cr(VI)-specific maximum contaminant level (MCL) for drinking water. Occurrence of Cr and As in municipal drinking waters and industrial cooling tower waters was quantified by grab samples and compared with sampling results obtained from a new passive sampler developed specifically for Cr(VI). Cr(VI) and As concentrations in groundwater used for cooling tower make-up water concentrations were ~3 ppb and ~4 ppb, respectively, and were concentrated significantly in blowdown water (~20 ppb and ~40 ppb). Based upon pending Cr(VI), As, and other metal regulations, these blowdown waters will need routine monitoring and treatment. Cr(VI) concentrations in a water treatment plant (WTP) raw and finished water samples varied from 0.5 and 2 ppb for grab samples collected every 4 hours for 7 consecutive days using an ISCO sampler. The development of an ion exchange (IX) based passive sampler was validated in the field at the WTP and yielded an average exposure within 1 standard deviation of ISCO sampler grab data. Sampling at both the WTP and cooling towers suggested sources of Cr(III) from treatment chemicals or wood preservatives may exist. Since both facilities use chlorine oxidants, I quantified the apparent (pH=5) second-order rate constant for aqueous chlorine (HOCl/OCl-) with Cr(III) to form Cr(VI) as 0.7 M-1s-1. Under typical conditions (2 ppb Cr(III) ; 2 mg/L Cl2) the half-life for the conversion of Cr(III) to the more toxic form Cr(VI) is 4.7 hours. The occurrence studies in AZ and CA show the Cr(VI) and As treatment of groundwaters will be required to meet stringent Cr(VI) regulations. IX technologies, both strong base anion (SBA) and weak base anion (WBA) resin types were screened (and compared) for Cr removal. The SBA IX process for As removal was optimized by utilizing a reactive iron coagulation and filtration (RCF) process to treat spent IX brine, which was then reused to for SBA resin regeneration.
ContributorsBowen, Alexandra (Author) / Paul, Westerhoff K. (Thesis advisor) / Hristovski, Kiril (Committee member) / Halden, Rolf (Committee member) / Arizona State University (Publisher)
Created2014
Description
The Future of Wastewater Sensing workshop is part of a collaboration between Arizona State University Center for Nanotechnology in Society in the School for the Future of Innovation in Society, the Biodesign Institute’s Center for Environmental Security, LC Nano, and the Nano-enabled Water Treatment (NEWT) Systems NSF Engineering Research Center. The Future of Wastewater Sensing workshop explores how technologies for studying, monitoring, and mining wastewater and sewage sludge might develop in the future, and what consequences may ensue for public health, law enforcement, private industry, regulations and society at large. The workshop pays particular attention to how wastewater sensing (and accompanying research, technologies, and applications) can be innovated, regulated, and used to maximize societal benefit and minimize the risk of adverse outcomes, when addressing critical social and environmental challenges.
ContributorsWithycombe Keeler, Lauren (Researcher) / Halden, Rolf (Researcher) / Selin, Cynthia (Researcher) / Center for Nanotechnology in Society (Contributor)
Created2015-11-01