The impact of combined sewer outflows on urban water quality: Spatio-temporal patterns of fecal coliform in indianapolis.

Many urban waterways with older stormwater drainage systems receive a significant amount of untreated or poorly treated waste from Combined Sewer Outflow (CSO) systems during precipitation events. The input of effluent waste from CSO to urban water streams during storm events often leads to elevated fecal coliform, specifically Escherichia Coli (E. Coli) in these waterways. The aim of the study is to examine fecal coliform concentration, water chemistry, and water quality parameters to better understand spatio-temporal patterns of fecal coliform associated with CSO events in three waterways from Indianapolis, Indiana (USA). The waterways are Pleasant Run Creek (PRW), Fall Creek (FC) and White River (WR). The sampling occurred biweekly over one year for PRW, nine months for FC, and an intense (∼every three days) sub-analysis of the presumed peak period of fecal coliform growth (July) for WR. All PRW and FC sampling sites significantly exceeded the EPA contact standard limit of 200 CFU/100 mL for fecal coliform concentrations during the sampling period. We found no relationship between fecal coliform levels and the number or density of CSO outfalls above a given site. The most significant predictors of increased fecal coliform concentrations were precipitation on the sampling day and cumulative degree days. The most significant predictors of decreased fecal coliform were maximum precipitation during the ten-day window prior to sampling and median discharge during a three-day window prior to sampling. These findings suggest a push-pull balance within the system where CSO activation and seasonal gradients replenish and promote fecal coliform growth. At the same time, large hydrologic events act to flush and dilute fecal coliform concentrations. The results from this study help us to better understand how different drivers influence fecal coliform growth and how this information can be potentially used to predict and remediate the conditions of urban water streams.

Using deciduous trees as bioindicators of trace element deposition in a small urban watershed, Indianapolis, IN, USA.

Annual and multiyear records of trace element deposition are difficult to develop using monitoring systems but have proven feasible using plant material in several settings. Here, we used material from several tree species (Populus deltoides W. Bartram ex Marshall, Platanus occidentalis L., and Ginkgo biloba L.) to detect atmospheric deposition of trace elements (Cd, Cu, Pb, and Zn) in six localities along a transect from near-urban to far-urban in southeastern Indianapolis, IN, and one control site. We captured soil (legacy footprint), bark (multiannual record), and leaves (seasonal record) across a broad swath of the urban landscape and using a multi-metal approach. Tree bark, leaf, and proximal soil samples were collected and analyzed for their trace element content. The highest trace metal concentrations occurred at the near-urban sites, with particularly high Cu and Pb values. The highest Zn values were found at one of the far-urban sites, which is located near a large brownfield that was a former coal and coke storage and processing facility. No correlation was found between soil trace element composition and that of bark and leaves, perhaps indicating a disconnect between legacy inputs recorded in soils and current inputs recorded in the biological materials. Overall, the tree species analyzed served well as trace element bioindicators, although less so for G. biloba, and thus this approach is promising for further understanding the role that airborne pollution and deposition play in urban watersheds.

Thorium impact on tobacco root transcriptome.

Thorium is natural actinide metal with potential use in nuclear energetics. Contamination by thorium, originated from mining activities or spills, represents environmental risk due to its radioactivity and chemical toxicity. A promising approach for cleaning of contaminated areas is phytoremediation, which need to be based, however, on detail understanding of the thorium effects on plants. In this study we investigated transcriptomic response of tobacco roots exposed to 200µM thorium for one week. Thorium application resulted in up-regulation of 152 and down-regulation of 100 genes (p-value <0.01, fold change ≥2). The stimulated genes were involved in components of jasmonic acid and salicylic acid signaling pathways and various abiotic (e.g. oxidative stress) and biotic stress (e.g. pathogens, wounding) responsive genes. Further, up-regulation of phosphate starvation genes and down-regulation of genes involved in phytic acid biosynthesis indicated that thorium disturbed phosphate uptake or signaling. Also expression of iron responsive genes was influenced. Negative regulation of several aquaporins indicated disturbance of water homeostasis. Genes potentially involved in thorium transport could be zinc-induced facilitator ZIF2, plant cadmium resistance PCR2, and ABC transporter ABCG40. This study provides the first insight at the processes in plants exposed to thorium.