Superfund Research Program
Improving Site Characterization to Assess Contaminant Removal
A computational model can be used to measure how different factors influence the removal of groundwater contaminants at hazardous waste sites, according to a study from the University of Arizona Superfund Research Program Center. Researchers led by Mark Brusseau, Ph.D., developed the predictive model and found that their contaminant estimates from the model compared well to measurements taken at a Superfund site.
Their model uses the relationship between reductions in contaminant discharge and removal as the metric to examine remediation efficiency. Characterization methods such as this may help researchers more easily understand factors that may impact the distribution of contaminants at a site, which can provide more information about the effectiveness of remediation efforts.
Building on these findings, the research team used the model to examine factors that influence contaminant removal in large groundwater contaminant plumes. Specifically, they looked at areas with low groundwater flow adjacent to large aquifer systems, which is common at many hazardous waste sites.
They found that the location of pump-and-treat wells, relative to contaminated water, can have a significant impact on how effectively contaminants are removed and how they persist in large groundwater systems. Based on well configuration, zones may be formed where contaminants remain stagnant, which reduces the effectiveness of pump and treat. This illustrates the need for dynamic system operations in which the system is routinely monitored and operational conditions are modified to maintain peak performance.
In a 2017 Risk e-Learning webinar, Brusseau described this work, as well as other efforts to improve characterization methods to understand the factors contributing to the persistence of contaminants in groundwater.
SRP Research Finds Ancestry-Based Differences in Telomere Length Genes
People with different ancestries may inherit telomere length differently, according to a new study from the Columbia University Superfund Research Program (SRP) Center. Telomeres are segments at the end of DNA, and telomere length plays an important role in aging and aging-related diseases. This study provides new information about the genes associated with telomere length across populations and highlights the importance of including diverse populations in genome-wide association studies (GWAS).
Although telomere length is a heritable trait, it still can vary considerably between individuals and populations, leading scientists to study how it is passed between generations. Previous studies that have investigated how telomere length is inherited have relied primarily on populations of European descent. In this study, researchers used samples from the Health Effects of Arsenic Longitudinal Study cohort in Bangladesh and found important ancestry-based differences in how telomere length might be passed on.
In addition to replicating some findings from other genome-wide association studies, such as those showing that gene regions called TERT and TERC are related to telomere length, the researchers also identified a new association. The study reports a link between telomere length and a gene region called RTEL1 and, importantly, a distinct second region of RTEL1 that had not been previously identified in relation to telomere length. This specific region of RTEL1 is common in South Asian populations but less so in other populations.
SRP Grantee Featured in Science Friday Video
Karletta Chief, Ph.D., of the University of Arizona Superfund Research Program (SRP) Center was recently interviewed on Science Friday. Her interview coincided with the release of the sixth and final installment of a short video anthology, "Breakthrough: Portraits of Women in Science," which follows women working at the forefront of their fields.
Bitter Water, the last film in the anthology, featured Chief and her SRP-funded work to address the concerns of the Navajo community after the Gold King Mine spill in 2015. In both the video and the interview, Chief explained how her research team helped identify more than 100 unique cultural uses of the river that were not previously considered in exposure estimates. They also studied how metals and other potentially toxic contaminants moved through the river’s sediment and water. Chief further shared her personal history and experiences leading her to become a hydrologist.
The Breakthrough anthology from Science Friday and the Howard Hughes Medical Institute blends the personal stories of women in science, technology, engineering, and math with highlights of their innovative scientific research and accomplishments.
Fish Adaptation to TCDD Seen at the Genome Level
Long-term exposure to environmental toxicants can affect the genome of Hudson River tomcod much more than previously expected, according to researchers led by Isaac Wirgin, Ph.D., at the New York University School of Medicine. A recent study led by Isaac Wirgin, Ph.D. and his team sheds light on the effects of exposure to the pollutant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the genomes, or full set of genes, from two tomcod populations 86 miles apart with distinctly different exposure histories.
The recent findings build on Wirgin’s Superfund Research Program (SRP)-funded work. The Hudson River Estuary in the New York City Metropolitan area has a long history of pollutants from both local and distant sources. In a study in the journal Science in 2011, funded in part by the SRP, Wirgin and his team describe how Atlantic tomcod in the Hudson River have genetically evolved to withstand the effects of pollutants, primarily polychlorinated biphenyls (PCBs), in the river.
In the new study, the researchers used larvae from both the pollutant-resistant Hudson River tomcod population and a non-resistant nearby Shinnecock Bay population. They exposed the two groups of larvae to TCDD and then compared the global expression of genes in the resistant and non-resistant tomcod.
They observed differences between the two populations in the number of genes that were expressed differently at all doses of TCDD. At the two lowest TCDD doses, 250 and 1,141 genes were differentially expressed in Shinnecock Bay larvae compared with only 14 and 12, respectively, in Hudson River larvae. At the highest dose, 934 genes were differentially expressed in Shinnecock Bay larvae and 173 in Hudson River larvae, but only 16 percent of affected genes were shared among both populations.
“I think the data is pretty dramatic in demonstrating just how great the effect of Hudson River-borne pollutants has been on the evolution of its tomcod population,” said Wirgin. “Pollutants can have far greater effects on exposed populations than we ever imagined.”
According to the authors, understanding differences in gene expression will allow them to better understand the toxic impacts of exposure and evaluate their mechanistic basis.
SRP Grantee Takes Cleanup Technology to the Field
Superfund Research Program (SRP) grantee Dibakar Bhattacharyya, Ph.D., of the University of Kentucky was recently awarded funding to help the Chevron Corporation remove metals and other potentially harmful contaminants from wastewater created during oil production.
Bhattacharyya's SRP-funded work was critical in laying the foundation that provided the opportunity to transfer his technology from the laboratory to the field. His team at the University of Kentucky SRP Center pioneered the development and use of specialized membranes to break down toxic organic compounds, such as polychlorinated biphenyls, trichloroethylene, and napthenic acids in water.
These membranes, which are embedded with nanoparticles in the lab, also can be used to capture metals like arsenic and mercury, making them ideal for the work with Chevron.