Spatial Distribution of Arsenic in Ohio Soils Nate Wanner, CPG MGIS Capstone Project The Pennsylvania State University Peer Review Presentation Adobe Connect July 26, 2016 Advisor: Dr. Patrick Drohan
Industrial Occurrence of Arsenic Manufacturing Glass Strengthens Lead recycling.com/Lead-battery-recycling.html Avoid Corrosion of Brass Coal Clinker on Rail Beds Light-Sensitive Semiconductors (GaAs LEDs, solar panels, etc.) Elemental Arsenic
Historical Use of Arsenic Yakima Valley Museum ail.do?groupId=5&lineId=285&productTypeId=64&productId= Treating Lumber Improving Complexion Murdering Lonely Bachelors Killing Insects and Rodents
Health Risks Related to Arsenic Cancer Skin lesions Developmental effects Cardiovascular disease Neurotoxicity Diabetes Exposure to arsenic from drinking water and food has been associated with:
Introduction When there is an industrial release, it is necessary to quantify the risk and respond appropriately, but... Arsenic occurs naturally in soils and groundwater This complicates site assessment and remediation, particularly in Ohio: –High natural concentrations –Industrial history –Relatively populous USGS:
Steps to Assess Releases: 1.Do maximum As concentrations exceed standards? 1.Identify how the land will be used. 2.Collect samples. 3.Determine if other contaminants are also present that could amplify risk. Contact PathwayOhio Standard Residential12 mg/kg Commercial/Industrial77 mg/kg Construction/Excavation690 mg/kg Photos:
Steps to Assess Releases: 2.Can another representative concentration be used, such as an average or 95 th Upper Confidence Limit? –Maximum of 13 exceeds a standard of 12. –Average concentration of sampled soil is 4.9 –We are 95% certain that the mean concentration of all soil (sampled and not) is not over
Steps to Assess Releases: 3.Do concentrations exceed background levels? –Ohio EPA county studies 6 complete 2 in progress 2 not started No plans for the other 78 –Site-specific studies Contact PathwayOhio Standard Residential12 mg/kg Commercial/Industrial77 mg/kg Construction/Excavation690 mg/kg
What Causes High As Levels? When is a site-specific study worthwhile? Should something other than per-county studies be considered? Potential considerations: –Surficial geology –Bedrock geology and glaciation –Soil types Are there subsets that show statistically significant distributions? –Normal, lognormal, etc.
Previous Studies Venteris, et al (2014) – Ohio State and ODNR –Used USGS National Geochemical Survey data and Gaussian simulation to compare arsenic concentrations to bedrock geology. Brief mention of glacial geology. AECOM (2010) – analysis of arsenic concentrations and bedrock geology in Ohio and 6 other states. –Spatial analysis by simple overlay, no evaluation of glacial geology –Identified data source following presentation, working on getting a copy Venteris Shallow SoilVenteris SubsoilAECOM Bedrock
Methodology to Identify Factors 1.Assemble data –Geology –Arsenic Concentrations –Soil Types. 2.Interpolation –Kriging 3.Overlay –Visual overlays 4.Correlation –Testing with regression or ANOVA 5.Risk model –The ideal long-term outcome of this project –Beyond the present scope of work
Assemble Data Initial evaluation used an Esri file geodatabase. I plan to add more data and conduct more QA/QC I will also include additional types of data such as soil types and sampling depths. I plan to use PostGIS so I can relate multiple tables.
Sources of Geologic Data Bedrock Geology from USGS ODNR Quaternary Geology ODNR Glacial Drift Thickness
Sources of Arsenic Data Ohio EPA background studies in 6 counties –High quality data, but limited number of sampling locations –Used laboratory data. Did not use XRF screening data Cox-Colvin Evaluation of Background Metal Concentrations in Ohio Soils (1996) –Data compiled from various background studies conducted near CERCLA/RCRA sites –Not Ohio Voluntary Action Program (VAP)-Certified USGS National Geochemical Survey Database –Compiled from various mineral exploration studies over the years. –Soil and stream data available – only soil data was used –Not VAP-Certified –Both atomic absorption data (AA) and inductively coupled plasma (ICP) mass spectrometry data were collected at each point. –Used AA data because there was only a single non-detect. Data from individual site studies and other consultants
Arsenic Data Points Initial datasets included data from over 2000 analyses of arsenic in soil. I anticipate adding over 500 analyses from approximately 60 additional locations.
Interpolation Kriging Mathematical method to interpolate values in mapping Originally developed for gold exploration in Africa Accounts for spatial variability by attempting to fit data to a smoothed mathematical function Based on changes over distance, and optionally direction Predictive or Probability Evaluating possible functions to model a semivariogram. From Geographic Information Analysis 2 nd Edition (O’Sullivan and Unwin ), Figure 10.9
Predicted Arsenic Concentrations
Probability of Exceeding 12 ppm 12 mg/kg (ppm) is the VAP Residential Direct Contact Standard.
Overlay: Sulfide Minerals in Shale? Evaluation of Venteris et al hypotheses that arsenic concentrations in Franklin County (Columbus) are associated with sulfide minerals in Devonian shales.
Correlation and Risk Model Correlation –If patterns may be present within a particular type of geology, they could be tested using regression or ANOVA. Risk model –The ideal long-term outcome of this project is to develop a risk model for predicting background levels of arsenic in soil. –However, many of the factors are not naturally quantitative so this will likely be difficult and beyond the scope of current work. All DataUnglaciatedLake InfluenceIllinoian GlaciationFranklin County Samples Minimum Maximum Standard Deviation Mean Distribution-Lognormal-Gamma- 95% Upper Confidence Limit (UCL) of Mean % Upper Prediction Limit (UPL)
Anticipated Timeline August 2016 –Incorporate peer review comments and complete data aggregation in PostGIS September 2016 –Analysis via QGIS and Python October 2016 –Report preparation November 2016 –Identify journal for publication and submit paper
Spatial Distribution of Arsenic in Ohio Soils Nate Wanner, CPG MGIS Capstone Project The Pennsylvania State University Peer Review Presentation Adobe Connect July 26, 2016 Advisor: Dr. Patrick Drohan Questions?
Bibliography Cox, C., & Colvin, G. (1996, June 21). Evaluation of Background Metal Concentrations in Ohio Soils. Retrieved November 17, 2015, from Ohio DNR. (2015A, November 17). Ohio Quaternary Map. Retrieved from Ohio Geology Store: map/4,59.html Ohio DNR. (2015B, November 17). Shaded Drift Thickness. Retrieved from Ohio Geology Store: thickness/4,60.html Ohio EPA. (2014B, August 1). OAC Appendix A: Generic Numerical Standards. Retrieved from Rules and Laws Governing the Voluntary Action Program: Ohio EPA. (2015A, November 17). Evaluation of Background Metal Soil Concentrations. Retrieved from il%20Concentrations.pdf Thomas, M. A. (2016). Arsenic in Groundwater of Licking County, Ohio, 2012-Occurrence and Relation to Hydrogeology. U.S. Geological Survey Scientific Investigations Report , 38 p. Retrieved from
Bibliography (continued) U.S. EPA. (2003, August 22). Ecological Screening Levels. Retrieved from U.S. EPA, Region 5: pdf USGS. (2014, May 21). Getting the Dirt on Soil. Retrieved from Science Features: USGS. (2015A, November 17). Ohio Geologic Map Data. Retrieved from Mineral Resources On-Line Spatial Data: USGS. (2015B, November 17). National Geochemical Survey Database. Retrieved from Mineral Resources On-line Spatial Data: Venteris, E. R. (2014, June 24). Modeling Spatial Patterns in Soil Arsenic to Estimate Natural Baseline Concentrations. Journal of Environmental Quality, Vosnakis, K. A., Perry, E., Madsen, K., & Bradley, L. J. (2010). Background Versus Risk- Based Screening Levels - An Examination Of Arsenic Background Soil Concentrations in Seven States. Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy, 14(10),