Evaluation of real-time fluorescence sensors and benchtop fluorescence for tracking and predicting sewage contamination in the Tijuana River Estuary at the US-Mexico border.

Cross-border flow of untreated sewage from Mexico into the USA via the Tijuana River is public health issue with negative consequences for coastal communities. Here we evaluate the potential application of fluorescence-based, submersible tryptophan-like (TRP) and humic-like (CDOM) fluorescence sensors for real-time tracking of wastewater pollution in an estuarine environment. Sonde fluorescence measurements were compared with benchtop fluorescence, fecal indicator bacteria (FIB) concentrations, and real-time specific conductivity measurements in the Tijuana River Estuary during dry and wet weather conditions, and with and without cross-border flow.

Micron-size tire tread particles leach organic compounds at higher rates than centimeter-size particles: Compound identification and profile comparison.

Tire tread particles (TTP) are environmentally prevalent microplastics and generate toxic aqueous leachate. We determined the total carbon and nitrogen leachate concentrations and chemical profiles from micron (∼32 μm) and centimeter (∼1 cm) TTP leachate over 12 days. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were used to measure the concentration of leached compounds.

Groundwater-surface water interactions and flux of organic matter and nutrients in an urban, Mediterranean stream.

The chemical quality of dissolved organic matter (DOM) and the speciation of nitrogen exported from urban catchments is of great importance to biogeochemical cycling in riverine and coastal receiving waters. Many urban streams in Mediterranean climates have a flashy hydrologic regime, which would suggest a rapid pulsing and shunting of solutes downstream. However, the role of these systems both as passive pipes for solute transport or as reactors for DOM and nutrient transformation is still an open question for urban, Mediterranean streams.

An Assessment of Ambient Water Quality and Challenges with Access to Water and Sanitation Services for Individuals Experiencing Homelessness in Riverine Encampments.

Individuals experiencing unsheltered homelessness face significant barriers to accessing water, sanitation, and hygiene services, but the risks associated with this lack of access and barriers to service provision have been largely understudied. We analyzed water samples upstream and downstream of three homeless encampments in the San Diego River watershed and interviewed service providers from public and nonprofit sectors to assess local perceptions about challenges and potential solutions for water and sanitation service provision in this context. Water upstream from encampments contained detectable levels of caffeine and sucralose.

Fluorescence-based monitoring of anthropogenic pollutant inputs to an urban stream in Southern California, USA.

Fluorescence spectroscopy has been increasingly used to detect sewage and other anthropogenic contaminants in surface waters. Despite progress in successfully detecting bacterial and sewage inputs to rivers over diverse spatial scales, the use of fluorescence-based in-situ sensors to track contaminant inputs during storm events and to discern bacterial contamination from background natural organic matter (NOM) fluorescence have received less attention. A portable, submersible fluorometer equipped with tryptophan (TRP)-like and humic-like fluorescence sensors was used to track inputs of untreated wastewater added to natural creek water in a laboratory sewage spill simulation.