Search for: All records

Forested watersheds are instrumental in providing purified and reliable water to millions of people worldwide. The changing climate has increased the frequency and severity of global fire events. Forested watersheds and their ecosystem functions are greatly disrupted during fire activity. Postfire concerns in forested watersheds include unpredictable and potentially simultaneous alterations in source water quality and hydro-biogeochemical processes. The degree of fire severity can complexly modify water quality through the production of fire-transformed constituents on the burned forest floor (i.e., nutrients, metal(loid)s, dissolved organic matter, and the formation of disinfection byproducts). Correspondingly, fire severity and postfire rainfall patterns can refine hydro-biogeochemical processes that influence the transport of the fire-transformed constituents (i.e., vegetation function, soil structure, hydrological pathways, and microbial communities). Postfire alterations to water quality and hydro-biogeochemical processes introduce further complexity with varying temporal influence, which ranges from months to decades. As postfire water quality and watershed response research progresses, it is essential to homogenize interdisciplinary expertise to bridge knowledge gaps between fields ranging from forest ecology, hydrology, microbiology, and geochemistry. A multidisciplinary approach in wildfire research will facilitate a comprehensive perception of the diverse water quality risks associated with fire activity and mitigate fire concerns on a global level. 

Several areas around the world rely on seawater desalination to meet drinking water needs, but a detailed analysis of dissolved organic matter (DOM) changes and disinfection by-product (DBP) formation due to chlorination during the desalination processes has yet to be evaluated. To that end, DOM composition was analyzed in samples collected from a desalination plant using bulk measurements ( e.g. dissolved organic carbon, total dissolved nitrogen, total organic bromine), absorbance and fluorescence spectroscopy, and ultrahigh resolution mass spectrometry (HRMS). Water samples collected after chlorination ( e.g. post pretreatment (PT), reverse osmosis (RO) reject (brine wastewater) (BW), RO permeate (ROP), and drinking water (DW)), revealed that chlorination resulted in decreases in absorbance and increases in fluorescence apparent quantum yield spectra. All parameters measured were low or below detection in ROP and in DW. However, total solid phase extractable (Bond Elut Priority PolLutant (PPL) cartridges) organic bromine concentrations increased significantly in PT and BW samples and HRMS analysis revealed 392 molecular ions containing carbon, hydrogen, oxygen, bromine (CHOBr) and 107 molecular ions containing CHOBr + sulfur (CHOSBr) in BW PPL extracts. A network analysis between supposed DBP precursors suggested that the formation of CHOBr formulas could be explained largely by electrophilic substitution reactions, but also HOBr addition reactions. The reactions of sulfur containing compounds are more complex, and CHOSBr could possibly be due to the bromination of surfactant degradation products like sulfophenyl carboxylic acids (SPC) or even hydroxylated SPCs. Despite the identification of hundreds of DBPs, BW did not show any acute or chronic toxicity to mysid shrimp. High resolution MS/MS analysis was used to propose structures for highly abundant bromine-containing molecular formulas but given the complexity of DOM and DBPs found in this study, future work analyzing desalination samples during different times of year ( e.g. during algal blooms) and during different treatments is warranted.