Measured physical/chemical properties of chemicals can be impacted by varying environmental conditions, subsequently influencing chemical environmental fate and exposure. For example, salinity has been reported to influence the water solubility of organic chemicals entering marine ecosystems. However, there is limited data available on salinity impacts on chemical sorption as well as bioavailability and exposure estimates used in the chemicals regulatory assessment. The salinity impact were demonstrated on the estimates of environmental fate of model compounds with different polarities including pesticides, and polycyclic aromatic sulfur heterocycles (PASHs). The n-octanol/water partition coefficient (KOW) was measured in both distilled-deionized water as well as artificial seawater (3.2%). A linear correlation curve estimated salinity may increase the log KOW value 2.6% per one log unit increase in distilled water (R2 = 0.968). The water solubility, bioconcentration factor, organic carbon soil/sediment sorption coefficient, and acute toxicity in fish were estimated for chemicals using the measured log KOW values by EPI SuiteTM. The water solubility of pesticides was measured in both distilled-deionized water as well as artificial seawater (3.2%). Salinity appears to generally decrease the water solubility and increase partitioning potential. Environmental fate estimates indicate elevated chemical sorption to sediment, bioavailability, and toxicity in artificial seawater suggesting that salinity should be accounted when conducting exposure estimates for marine organisms. In addition, the relative impact of volatilization and hydroxyl radical degradation on estimates of PASH overall dissipation after entry into aquatic ecosystems as a function of depth (0.1, 1 and 2 m) were investigated using the EPA Exposure Analysis Modeling System (EXAMS). The hydroxyl radical rate constant (K.OH) and Henrys law constant (H) of PASHs were determined in distilled water. Simulated dissipation of PASHs using EXAMS suggest that volatilization is a dominant fate pathway for the higher molecular weight and less polar C2-DBT and C4-DBT at all depths and DBT and C1-DBT at 0.1 m. However, model scenarios suggest hydroxyl radical degradation may significantly contribute to the degradation of more polar DBT and C1-DBT at 1 m and 2 m depths.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-02022017-104439 |
| Date | 07 February 2017 |
| Creators | Saranjampour, Parichehr |
| Contributors | Marx, Brian, Armbrust, Kevin, Lomnicki, Slawomir, Overton, Edward, Mooney, Paul |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-02022017-104439/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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