Search

7 pages, 3 tables, 3 figures.-- Under a Creative Commons license, Determining the background is a crucial step in differentiating between natural and anthropogenic components in environmental samples. Geochemical normalization is a standard procedure for determining the background contents of trace elements in sediment samples, which involves the careful selection of a reference element. Aluminum (Al), iron (Fe), and other major, minor, and even trace constituents of sediments are commonly used as reference elements. A suitable reference element should behave conservatively, with contents that are not significantly affected by anthropogenic factors or post-depositional processes. In this study, the performance of uranium as a reference element in sediment samples taken from the Ulla River was tested. The Ulla River drains a mainly granitic basin in the Iberian Atlantic Margin, and samples were collected from headwaters to the coastal area. Iterative least squares simple regression was used to estimate the background contents (as background functions) of six trace elements of environmental concern, including arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Uranium demonstrated satisfactory performance with correlation coefficients ranging from approximately 0.7 for Cu to 0.9 for As. The background-estimated contents of the six target elements were in good agreement with several references at different geographical scales, with differences possibly attributed to peculiarities in the local lithology. Thus, uranium can be considered a suitable normalizing element. However, it was tested in a relatively homogenous granitic basin and, like any other reference element, should not be used automatically without empirical corroboration, M.A. Álvarez-Vázquez was supported by ‘Xunta de Galicia’, postdoctoral grant #ED481B-2019-066. This study is a contribution to the project AMBARULLA (Spanish Research Council – CSIC code: 20181970) and to the award of “Consolidation and Structuring of Competitive Research Group”: Océano (code IN607A2021/04 – Xunta de Galicia). Funding for open access charge: Universidade de Vigo/CISUG

Over the years, industrial activities that generate high salinity effluents have been intensifying; this has relevant potential for causing organic and microbiological pollution which damages both human and ocean health. The development of new regulations, such as ballast water convention, encourage the development of treatment systems that can be feasible for treating seawater effluents. Accordingly, an approach based on the UV activation of persulfate salts has been assessed. In this scenario, two different persulfate sources (S2O82− and HSO5−) were evaluated under UV-C irradiation for disinfection purposes. An optimization process was performed with low chemical doses ( E. coli > E. faecalis ≈ Marine Heterotrophic Bacteria. With an evaluation of regrowth after treatment, greater cell damage was detected with the addition of persulfate salts. The major ability of regrowth for marine bacteria encourages the use of a residual disinfectant after disinfection processes.