Plasticizers are plastic additives used to enhance the physical properties of plastic and are ubiquitous in the environment. A class of plasticizer compounds called phthalate esters that are not fully eliminated in wastewater treatment facilities are relevant to the ecological health of downstream ecosystems and urban areas due to their ecotoxicity, tendency for soil accumulation, and the emerging concern about their effects on public health. However, plasticizer concentrations in a constructed wetland environment have rarely been studied in the United States, prompting the need for a method of plasticizer quantification in the Tres Rios Constructed Wetlands which are sustained by the effluent of the 91st Avenue Wastewater Treatment Plant in Phoenix, Arizona. The concentrations of four common plasticizer compounds (dimethyl: DMP, diethyl: DEP, di-n-butyl: DnBP, and bis(2-ethylhexyl): DEHP phthalate) at five sites across the wetland surface water were quantified using solid-phase extraction followed by gas chromatography coupled with mass spectrometry (GC/MS). The sampling period included four sample sets taken from March 2022 to September 2022, which gave temporal data in addition to spatial concentration data. Quantification and quality control were performed using internal standard calibration, replicate samples, and laboratory blanks. Higher molecular weight phthalates accumulated in the wetland surface water at significantly higher average concentrations than those of lower molecular weight at a 95% confidence level, ranging from 8 ng/L to 7349 ng/L and 4 ng/L to 27876 ng/L for DnBP and DEHP, respectively. Concentrations for dimethyl phthalate and diethyl phthalate were typically less than 50 ng/L and were often below the method detection limit. Average concentrations of DnBP and DEHP were significantly higher during periods of high temperatures and arid conditions. The spatial distribution of phthalates was analyzed. Most importantly, a method for successful ultra-trace quantification of plasticizers at Tres Rios was established. These results confirm the presence of plasticizers at Tres Rios and a significant seasonal increase in their surface water concentrations. The developed analytical procedure provides a solid foundation for the Wetlands Environmental Ecology Lab at ASU to further investigate plasticizers and contaminants of emerging concern and determine their ultimate fate through volatilization, sorption, photodegradation, hydrolysis, microbial biodegradation, and phytoremediation studies.

Halogens in drinking water sources, such as bromine (Br) and iodine (I) pose no direct health risk, but are critical precursors in formation of cyto- and genotoxic brominated and iodinated (Br-/I-) DBPs. However, few spatial or historic datasets exist for bromine and iodine species in drinking water sources. This dissertation aims to quantify and understand the occurrence and speciation of Br and I in groundwater and surface water serving as source waters for drinking water treatment plants (DWTPs). Aggregation of data from >9000 non-drinking water sampling locations in USA collected from 1930-2017 on halides (bromide (Br-) and iodide (I-)) determined that Br- concentrations were 50 μg/L and 100 μg/L; and I- concentrations were 12 μg/L and 13 μg/L in surface and groundwater respectively. Although, these locations were not drinking water sources, this first of its kind analysis provides potential bounds for Br- and I-. To focus specifically on DWTP sources, a nationwide survey of >250 drinking water sources was conducted between 2018-2020. Br- ion is the only bromine specie, whereas both inorganic (iodide and iodate ions) and organic iodine occur. I- concentrations ranged from 1-250 μg/L and are 4 to 100 times lower than Br- concentrations (10-7800 μg/L, median=80 μg/L). No strong correlation exists between bromide and iodide occurrence (R<0.5, p<0.005). I- was detected in 50% of the samples (75th percentile=5 μg/L) and IO3- was detected in 40% (75th percentile=3 μg/L) of all the samples. To quantify iodine species, tandem ion chromatography and inductively coupled plasma mass spectrometry was applied for the first time in drinking water sources. I- and IO3- peaks were well resolved and have minimum detection limit of 0.4 μg/L and 0.7 μg/L respectively. Organic iodine (Org-I) peaks in select drinking water samples from the nationwide survey were partically resolved ranging from <5 to 40 μg/L. This dissertation provides updated nationwide Br- survey and first ever national I species survey. The data generated through this dissertation will be useful to further Br-/I-DBP formation and toxicity research by providing relevant drinking water sources information. Future research targeting Br- and I- removal is advocated for managing Br-/I-DBPs in watersheds.