Seasonal Cytotoxic Effects of Urban Watersheds in the Greater Houston Area

Abstract

Steadily rising populations are turning Houston, Texas to the urban concrete jungle it is today. With communities growing and searching for homes, the need for new construction and establishments only increases the amount of impermeable surfaces relying heavily on the native waterways. Houston is known for its complex network of waterways surrounding and interweaving throughout the city, which are referred to as bayous. They work as a storm water runoff system to help prevent flooding, but many communities use the watersheds for recreational purposes. Local patrons boat, fish and swim in the bayous, unaware of the chemicals and pollutants lurking in the water. Due to the extensive flood history in Houston and the surrounding areas, communities do not have to be near the bayou to be inundated with the polluted water. Heavy rain for only an hour or two can cause bayous to rise, streets flood and water can make the find its way into low‐lying homes. Current studies have shown that there are high concentrations of As, Hg, Cr, Pb and Zn in the water. We hypothesize that the metals and chemical compounds identified could cause the water to have deleterious effects on living organisms occupying the watersheds or using its resources. My study objectives include observing the cellular response when the cells are subjected to the bayou water samples collected during the summer and fall of 2018 to compare cellular viability and to determine which of the watersheds has the greatest over cytotoxic effects.Water samples were collected in triplicates from Mustang Bayou, Dickinson Bayou, Horsepen Bayou, Houston Clear Lake, Cypress Creek and Cypress Creek Lake, which are six major waterways in the surrounding Houston area. The methods included buffering the water sample that will not be detrimental to the cells, then serial dilute the samples in media for varying concentrations (control or 0%, 12%, 25%, 50%, 100%) and tested the bayou water samples on the HT29 colon cells using a cytotoxicity assay and proliferation assays at 12, 24, and 48‐hour time points.We observed a linear decrease in viable cells as the treatment time points of bayou water increased. Cytotoxic effects were observed at every time point no matter the concentration of bayou water in the sample and the highest overall cellular viability was observed in the fall 2018 samples, because the overall viability percentages were roughly 20% higher than summer samples for both the 12hr and 24hr treatments although the 48hr results stayed consistent. Future studies include treating FHC colon cells with the same bayou water concentrations to compare to the HT29 cellular response and investigate the cytotoxic cellular effect with media containing the chemical elements at the concentrations determined from the chemical analysis.Support or Funding InformationThis research was primarily supported by the National Science Foundation (NSF) through Texas Southern University (TSU) under the award numbers HRD‐1622993, BCS‐1831205, and HRD‐1829184