Passive samplers could improve hydrogen sulfide monitoring near CAFOs

By on May 24, 2013
A passive sampler housed under a section of rain gutter measures hydrogen sulfide near an Iowa CAFO (Credit: Brian Pavilonis)

An inexpensive and simple monitoring technology could help environmental health officials and scientists keep better track of the potentially harmful gasses emitted by massive livestock feeding operations, according to a recent study.

Studies have found that cases of asthma, wheeze and upper respiratory infections appear to be more common among people living near concentrated animal feeding operations, or CAFOs, that can typically house more than 2,000 livestock animals. But the associations that these studies draw between CAFOs and health problems have relied on proximity to the facilities rather than quantitative measurements of potential contaminants, according to Brian Pavilonis, a postdoctoral fellow with the Environmental and Occupational Health Sciences Institute at Rutgers University.

“There is this feeling that, ‘Well, it looks like an association, but we don’t really know what’s causing it,'” Pavilonis said. “There have been a lot of people that want to get at how we can effectively measure exposure near CAFOs. ”

One hurdle to quantifying the airborne pollutants around these facilities is the high startup costs of the direct-read instruments used to measure gases like hydrogen sulfide. These tools also need a constant source of power to run, which can be a challenge in the rural environments surrounding CAFOs.

“They’re sited, specifically, in the middle of nowhere,” Pavilonis said. “So there are no power outlets out there. Also, a CAFO is about the size of a football field, so it’s very hard to site a lot of direct-reading instruments around CAFO.”

But Pavilonis has been working with a device that could work around those obstacles. As a graduate student at the University of Iowa, he spend around two years monitoring hydrogen sulfide around Iowa feeding operations with Radiello passive samplers. The results of the study were recently published online by the journal Environmental Science: Processes and Impacts.

The samplers are relatively inexpensive and work without electricity. The gas diffuses through the sampler body and attaches to an absorbent cartridge, where it reacts to form a stable compound that can be quantified through simple lab analysis.

The research focused on hydrogen sulfide–known for its rotten egg smell–because it’s a contaminant generated by the waste stored on site. On its own, the gas can at low levels exacerbate asthma and cause shortness of breath, nasal irritation and other respiratory complaints. It’s also useful as a surrogate measurement for other air pollutants associated with hog manure, Pavilonis said.

For the first phase of the study, the researchers installed samplers at eight locations in a grid around a single facility that Pavilonis said was fairly representative of CAFOs across the U.S. The facility stored liquid waste in a lagoon, a pit without overhead containment.

Hydrogen sulfide concentrations over the seven-month sampling period were highly variable, Pavilonis said.

“Right near the lagoon, you could have measurements over two weeks up to 50, 60 parts per billion,” he said. “And two or three hundred feet away you’re getting almost right at the limit of detection.”

In a second phase of the study’s monitoring, a single sampler was installed at the fence line of 13 CAFOs, along with two more at schools near feeding operations. The concentrations at the schools were generally low, while the highest concentration was found at the facility permitted to house the largest volume of animals among those sampled.

But the number of animals in a facility isn’t always a good predictor of pollutant levels, Pavilonis said.

“It’s really hard to understand why concentrations at different CAFOs are different,” he said. “Manure management is a huge part of how much hydrogen sulfide is produced.”

The study is an early look at the potentially of passive samplers to monitor CAFOs, and it suggests that there is still work to be done to understand how the measurements are affected by environmental conditions like temperature. But they appear to show potential to get scientists and regulators closer to quantifying air pollutants around these facilities.

“And that’s why I went into this [study],” Pavilonis said. “How can people use new tools to monitor different contaminants near CAFOs?”

Top image: A passive sampler housed under a section of rain gutter measures hydrogen sulfide near an Iowa CAFO (Credit: Brian Pavilonis)

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