Join me for a drive through California’s San Joaquin Valley. Perhaps best known for agriculture, the Valley’s vast sea of tasty fruits and vegetables begins to overwhelm us as we drive down the freeway. You can even smell the garlic through the windows!
As we sit in gradually-building traffic, other observations stand out. Oil rigs and dairies dot the road. The gases coming from traffic and industry create a soupy mix of pollution that clouds our view as we continue our drive.
We finally arrive at our destination: a dairy farm in Visalia, California. As we drive onto the property, the strong smell of cows overwhelms our senses. The smell is strongest near the dairy’s manure lagoons, which are filled to the brim with liquid waste from the cows.
The Valley is dotted with thousands of these uncovered lagoons. Dairy operators build them to manage manure from their animals. Some dairy farms have only one or two, while others have as many as twenty. Although the strong smell is undoubtedly the first thing you would notice as we arrive, it’s not the biggest problem.
Lagoons release huge amounts of greenhouse gases like methane and carbon dioxide. Greenhouse gases are good in moderation. They keep our world at a comfortable living temperature. Without them, our Earth would be frigid and uninhabitable. However, when there are billions of people driving, cooking, managing dairy farms, and growing food all over the world, the extra greenhouse gases quickly tip the scale. These extra gases polluting our air can lead to health problems and even cause our climate to change. Understanding, monitoring, and reducing greenhouse gas emissions is the only way to prevent these large-scale changes.
California leads the way in trying to lessen greenhouse gas emissions, and the state has very ambitious reduction goals in place. Over the next decade, California plans to cut back emissions to low levels not seen since the 1990s. However, the state disagrees about greenhouse gas sources and amounts. Without knowing where and how much, it is nearly impossible to figure out how to cut back.
Scientists have discovered that the largest uncertainty in emissions is in the San Joaquin Valley, mostly from dairies. Dairy farms will need to reduce emissions so California can reach its reduction goals in time. It is not enough for dairy farms to own fewer cows. Modern technology should be implemented to decrease emissions. Despite these grand plans, the dairy industry is still not well regulated. This need for stricter rules will directly affect Central Valley residents at the forefront of these reductions. Luckily, we have the tools to reduce the uncertainty in dairy emissions.
We park the car and unload about a hundred two-liter, stainless steel canisters. The canisters have been pumped out ahead of time. When we open a canister, it will suck in air automatically. Over 300 samples have been collected at this dairy so far, and today we will collect more.
Using the canisters to collect samples is flexible and convenient because we have total freedom over the sample strategy. We can walk around the dairy and collect samples in places that are likely to have high amounts of gases (like downwind of manure lagoon). We can also pile the canisters into a vehicle and drive around while collecting samples. This mobile lab looks like the Scooby Doo van filled with, instead of snacks, scientific equipment that shows us what the levels of greenhouse gases are in real time.
We put the canisters into the mobile lab and drive around the dairy. We stop to collect samples where the cows eat as well as around the lagoons. We also collect samples upwind and downwind of the dairy.
Once we fill up all the canisters, we will transport them back to the lab for analysis. We can analyze these samples to figure out how much methane, carbon dioxide, and other gases come from cows and manure lagoons on dairy farms. By better understanding these emissions, dairy operators will know the best way to reduce them. For example, if most of the gases come from the lagoons rather than the cows themselves, dairy operators could cover and trap the gases from the lagoons.
It would be difficult for us to visit all the dairy farms in the Valley. It would be much easier if we could fly around and collect samples anywhere. It turns out this is not a futuristic dream—we can put our canisters on an airplane. My lab has been collaborating with NASA for over a decade to measure what gases we can “see” thousands of feet above California. This data shows greenhouse gas trends over the years and can give us more big-picture information about how the dairy farms impact air quality. I plan to compare these readouts to the air we collected in our Scooby Doo mobile lab to determine the influence of dairy farms on the Valley.
Although living in California during the big push for greenhouse gas reductions is a challenging and intimidating time, hope exists. Dairy farms in the San Joaquin Valley, like the one that we visited in Visalia, are open to positive change. Many of them have begun installing bioreactors. These bioreactors can trap greenhouse gas emissions that come out of the manure lagoons and turn them into electricity! This is an opportunity to not only reduce harmful emissions, but also to help local communities power their homes and businesses. In a few years, maybe dairy farms could become self-powered using their own emissions—this would save them money and clean up air quality! By fully understanding how dairy farms influence our air, we can make California a greener, cleaner, and better place to live.
Sources:
- Senate Bill 32 of 2016, Governor’s Executive Order B-30-15.
- Jeong, S., Newman, S., Zhang, J., Andrews, A. E., Bianco, L., Bagley, J., … & LaFranchi, B. W. (2016). Estimating methane emissions in California’s urban and rural regions using multitower observations. Journal of Geophysical Research: Atmospheres, 121(21), 13-031.
About the Author:
Brenna Biggs is a 4th year PhD candidate in the Department of Chemistry. As part of the Rowland-Blake group, she collects air samples all over the world. She is specifically interested in understanding air quality around landfills and dairy farms in California, and how those industries influence local communities and surrounding natural environments. Read more article by Brenna on The Loh Down on Science