Crowdsourcing hydrocarbon pollution monitoring in shale areas using passive sampling

Methods

Summary

We employ the Radiello cartridge and diffusion tube system to passively collect hydrocarbons from ambient air on a continuous weekly basis. The Radiello system allows various combinations of an adsorption tube and an outer diffusion tube. We have tested two of those combinations in the laboratory (see video) and will keep testing them using our dilution and chamber equipment in the lab. From our tests, we derive "uptake rates" for selected hydrocarbons, which we use to estimate ambient air concentrations during the week-long exposure.

To calibrate our measurements, we use the same adsorption material (a "Carbopack" adsorbent) in an actively (aka via a metered pump) collect hydrocarbons from a calibration gas standard tank.

In the field, the volunteer collaborating with us at the deployment site maintains a small rain-out shelter that houses two diffusion tubes with the carbon adsorbent cartridges (two replicates). Once a week, the volunteer switches out the exposed cartridges with fresh ones s/he received in the mail, then returns the exposed cartridges and the field blank to us, also in the mail (we use a homemade foam-box for shipping).

We quantify the amount and types of identified hydrocarbons within 1-2 days after receiving the samples, and inform the volunteer of the results regularly, including lay-person accessible explanations of relevance and significance.

Challenges

A learning curve is expected with all volunteers as the adsorption cartridges are somewhat fragile, and may have to be replaced regularly. 

Weather conditions around sample turn-over time could be an issue when trying to minimize shipping costs. This may have to be worked out at each site independently.

Pre Analysis Plan

Data from 1-3 sites will come in weekly, creating an expanding data set. It will take some time, we expect up to half a year, to judge whether the observations are meaningful. To increase comparability, we hope to find a volunteer who would operate a station next to a state-run monitoring station, which can provide increased confidence in our results.

If successful, we ultimately want to publish the results in an open-access scientific journal, relating the observations, which are representative of exposure to hydrocarbons at the measurement location, to public, ambient air quality data from state and academic sources in similar environments. In addition, we hope to expand our efforts if they prove to be meaningful, both scientifically and from the standpoint of our volunteers.