Posted on 27 February 2012.
Born in San Diego, CA, Justin Richardson is a first-year graduate student in Dartmouth’s Earth Sciences department. Describing himself as “the soil man,” Justin’s research examines how toxic metals are transported in upland forest soils. As an undergraduate at University of California, Riverside, Justin worked as a Soil Science Adviser at his campus’s organic community garden, and for the nine months that he has been a member of the Dartmouth graduate community, he has used his knowledge of soils to assist instructors with the educational courses held at the Dartmouth Organic Farm. At the community farm in Southern California and Dartmouth’s Organic Farm, Justin applied his knowledge of sustainable farming methods to control the nutrient levels in each farm’s soil.
Justin’s graduate research builds upon his deep-seated interest in soil science and environmental sustainability. As a graduate student, Justin is researching the ability of soils from different regions of the northeastern United States to retain mercury—a toxic metal released into the atmosphere during coal combustion—and lead—a heavy metal released by automobiles before leaded gasoline was phased out in the 1970s. The organic matter and mineral content present within soils creates a buffer that slows the leeching of these metals into the region’s subterranean aquifers; once in the aquifers, these metals gradually move up the food chain. Though research suggests the lead that enters our waterways is not absorbed by humans, it has been proven that humans absorb mercury through the consumption of predatory fish that feed in contaminated waters.
“Though mercury isn’t good for you, I still enjoy eating locally caught fish,” says Justin. “You just have to watch which species you consume.”
Currently, Justin is examining the heavy-metal retention properties of both the organic matter and mineral content of various soils, which differ greatly from region to region. Comprised primarily of decomposing plant matter, the organic structures of a forest’s floor determines how well it is able to retain metals: in evergreen forests, the carbon structures of the fallen pine needles are relatively stable and are able to hold metals for longer than the carbon structures of the downed leaves in deciduous forests, which fall from the hardwoods of New England each autumn.
The mineral content of a soil is the final buffer that slows the leaching of lead and mercury into the waterways of the Northeast. After passing through the forest floor, different minerals hold toxic metals before they move into the subsoil. Recent studies suggest that the greater the clay content of a soil, the better it is at retaining toxic metals. Currently, Justin is examining the ability of New England’s soils, which vary in their clay content, to retain lead and mercury.
“Although there aren’t that many coal-burning plants in New England, there is a major mercury problem in this area,” says Justin. “The mercury released by coal plants in the midwestern United States travels through the atmosphere, and ends up in our soils.”
This summer, Justin helped teach laboratory sections held at the Dartmouth Organic Farm to the school’s ecological agriculture class. Located three miles up river from Dartmouth’s campus, the Organic farm is an educational facility that teaches students methods for sustainable food production. Unlike the organic community garden Justin worked at as an undergraduate—which is divided into small land plots that students and community members manage independently—Dartmouth’s Organic Farm is not partitioned, which allows for greater control over both the nutrient levels in the soil and the prevention of parasitical crop damage through organic farming methods. Justin explains that this structural feature of Dartmouth’s Organic Farm makes the facility well suited for teaching.
“One thing that’s unique about Dartmouth’s Organic Farm is that the farm is built upon the official ‘Dartmouth series soil,’” explains Justin. “The official soil taxonomic name for many of the low lying areas along the Connecticut River Valley is named after our school, and I think that’s something that Dartmouth students should know.”
To become involved in Dartmouth’s farming community, drop by the organic farm anytime to learn about its seasonal happenings. In the summer, students run a farmstand outside of the Collis Center where they sell fresh produce to the community. If you’re new to horticulture, Dartmouth’s Organic Farm holds “work days” designed to teach students the basics of sustainable farming; the farm also hosts pot-luck dinners on a regular basis for everyone who helps out at the farm.
If you’d like to learn more about Dartmouth’s Organic Farm, or are interested in soil science, it’s easy to spot Justin in Hanover: his NH license plate is “SOILSCI.”
by Wesley Whitaker