EAR-PF: Environmental source apportionment and soil-household dust relationships of urban metal pollutants across different regions and seasons

An NSF EAR Postdoctoral Fellowship has been granted to Dr. Matthew Dietrich to conduct research and scientific outreach activities at Indiana University–Purdue University Indianapolis (IUPUI) under the mentorship of Professor Gabriel Filippelli. Research will be focused on understanding the complex relationships between heavy metal pollutants in urban soils and urban household dusts, with a particular focus on lead (Pb).

Pb is a toxic element that especially affects children, leading to adverse health effects such as cognitive impairment. Hundreds of thousands of children in the U.S. still have blood Pb concentrations that harm their development, and this disproportionately affects children of color. Research in understanding mobilization, transport, and the sourcing of Pb and other heavy metals in urban environments is underdeveloped, particularly in the U.S., and is essential for efficient intervention and addressing environmental justice issues.

Thus, through using community members in two contrasting urban centers, Indianapolis, U.S. and Sydney, Australia, Dr. Dietrich will analyze household dust and soil samples to better understand where the heavy metal pollutants are coming from and how seasonal, climatic, and geologic variability affects the transfer of pollutants in dusts and soils. Innovative geochemical techniques such as copper (Cu), zinc (Zn), and Pb isotopes will help with assigning proportions of specific pollutant source contributions, while high resolution imaging such as scanning electron microscopy (SEM) will help characterize pollutant particles in the dusts and soils.

Outreach and community involvement in this project is essential, as local community members in each city will provide samples from their own households, which not only improves sampling resolution, but will allow Dr. Dietrich to directly communicate findings to the community members and the action steps they can take if pollution is detected. Additionally, scientific education to both community members supplying the samples and the greater community at large is an essential part of this project.

Specifically, partnerships with local inner-city high schools in Indianapolis and undergraduate classes at IUPUI will help in both dissemination of results and additional sampling. All data will eventually be freely available at www.mapmyenvironment.com, providing the ideal platform for accessible data for both research scientists and community members alike.

Through using household dusts and soils from homes in Indianapolis, U.S. and Sydney, Australia, this research will address whether pollution source apportionment and soil-dust relationships at the household scale can be agglomerated together to provide useful trends at the city scale. A large sample set collected with the help of local community members offers a unique opportunity to holistically utilize geochemical techniques to investigate heavy metal pollution at scales typically not easily accessible for research.

The techniques utilized will be full geochemical characterization of urban dusts/soils (e.g., mineralogy, percent organic carbon), and multiple metal isotope (Pb, Zn and Cu) ratios/multivariate statistics (i.e., principal component analysis) to differentiate between pollutant source endmembers (i.e., soils, house paint, vehicle wear, etc.) and the household dust to which children and adults are routinely exposed. These techniques will help answer the research questions: (1) why are some metals such as Cu and Zn (but not Pb) much higher in dusts relative to soils, and do different geographic regions have differing soil-household dust element correlations because of differing mineralogy, climate, and other geochemical characteristics?, (2) do household dusts contain different isotopic ratios and therefore pollutant sources in some seasons compared to others?, and (3) is there regional household dust isotopic variation between Sydney and Indianapolis that points to variation in geogenic background, climate, or pollutant sources in an area?

The novel approach of using multiple metal isotopes for source apportionment with multivariate statistics over different spatial and temporal scales provides a new and improved holistic framework for better identifying the greatest threats to human heavy metal exposure. Greater understanding of inorganic pollutant cycling in urban settings will ultimately enable more efficient intervention methods and thus improved support for pollution remediation, particularly in areas disproportionately affected by pollution.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.