Clean Soil, Safe Food
“We try to improve soil health and to produce safe food by understanding the soil contaminants—all contaminants—especially those of emerging concern.”
An expert in analyzing the chemical behaviors of soil and soil contaminants, his more than 19,000 citations put Xing in the top 0.1 percent of cited authors for journals in his discipline, indicating the originality, impact, and significance of his research.
When asked to describe his work in a nutshell, Xing, who came to UMass Amherst in 1996 after receiving his PhD in environmental and soil chemistry from the University of Alberta, sums it up succinctly: clean soil for safe food.
“We try to improve soil health and to produce safe food by understanding the soil contaminants --all contaminants—especially those of emerging concern such as antibiotics, pharmaceutical compounds, and, lately, we are working with engineered nanoparticles,” says Xing.
His approach to understanding soil contamination and its environmental impact is twofold: to enhance soil quality by taking advantage of the soil’s chemical and physical properties and to understand the behavior of soil contaminants in order to minimize or eliminate their uptake by food crops.
“We don’t want contaminants in produce, in the agricultural products to negatively affect the health of those who eat them. To reach our goals, we first needed to understand the soil composition,” says Xing.
To that end, his early work focused on developing a number of widely used spectroscopic techniques to analyze soil organic matter (SOM).
“Soil organic matter is one of the indicators for soil health, just like blood pressure is for human health,” says Xing. “Once we know the organic matter structure, then we know how organic matter promotes soil health, including how matter can attenuate contaminants in soil.”
Xing’s groundbreaking research on SOM-mineral interactions provided much-needed explanations for the long-term persistence of organic contaminants and for carbon sequestration in soils. This work spurred his interest in developing an ancient method of soil enhancement that had been used in the rainforests of Brazil (among many other places) called biochar to remediate soil contaminants.
“A thousand years ago, people didn’t know the properties of the soil. But they knew if they put charcoal in the soil, the soil performed better. About 10 years ago, a lot of researchers got into this field. Before that, we didn’t know much about biochar for soil improvement,” says Xing.
As biochar pioneers, Xing and his colleagues discovered biochar was recalcitrant—resistant to microbial degradation and able to trap carbon in the soil for long periods of time. “You notice the beautiful leaves. Once they fall to the ground, in three, maybe four years, they will degrade, return most of the organic matter into the atmosphere as CO2. But if you convert this biomass waste into char, then it can last in the soil 100 years or 1000 years, depending on how you make the char. This is good for the climate because it can mitigate the greenhouse effect,” says Xing.
Biochar can also trap other chemicals in the soil, such as contaminants, notes Xing. “Biochar adsorbs them, ties them up. They are still there, but they are not available for the plants to uptake. We are trying to find an economical way to immobilize or reduce the mobility of toxins in the soil.”
With this in mind, Xing and others in his research group are investigating smart or “designer” biochar, to target specific aspects of soil improvement. “With designer biochar we try to understand what type of problems a soil has, such as acidity issues, metal contamination, or organic contaminant problems. Then we design this special char to target that soil’s problems.”
Xing’s newest area of research delves into a topic of emerging environmental concern, engineered nanoparticles (ENPs).
“I first want to say I am a proponent for nanotechnology. In this century, two technologies already affect our daily lives: biotechnology and nanotechnology. Nanotechnology brings so many benefits to human kind. But like anything, when you have so many benefits, you may have some side effects,” says Xing.
Because nanoparticles have unique properties, there is a risk that some can cause harm to organisms, such as bacteria, plants, and animals, including humans. “So we try to study the chemical behavior and toxicity of nanoparticles,” says Xing. “How do they effect bacteria and algae? How do they affect plant growth?”
Xing is particularly interested in the trophic transfer of contaminants, meaning which contaminants are bio-accumulated through the food chain. “We study from soil to plant to animal. The worm eats the plant leaves then the baby chicken eats the worm. We study all of the behavior with the goal of understanding their environmental behavior and to minimize our exposure through food consumption,” says Xing. Xing’s latest book, Engineered Nanoparticles and the Environment: Biophysicochemical Processes and Toxicity, which was published by John Wiley and Sons in October 2016, covers many of these issues.
“The book explores exposure and environmental risk assessment for ENPs and how we can produce safe food when using nanotechnology. Our goal is to promote safe, sustainable, nanotechnology. We will have more ENPs in our environment. We have to understand their exposure and toxicity,” says Xing.
Next up for Xing is a collaboration with food scientist and campus colleague Dr. Lili He to develop a quick, handy technique to identify and analyze nanoparticles on vegetables. The partnership takes advantage of Xing’s early work in developing spectroscopic techniques and his growing knowledge of ENPs, which match well with He’s expertise and work on surface-enhanced Raman spectroscopy (SERS), a technique that is being explored for detecting all types of contaminants in food. “We are applying for a patent. We are not there yet, but hopefully we can make this available for use by the public in a few years.”
Baoshan Xing is a Fellow of the Soil Science Society of America (SSSA) and the American Society of Agronomy (ASA). Other significant honors include the Kingenta Agricultural Science Award (2013), the ASA Environmental Quality Research Award (2016), the SSSA Marion L. and Chrystie M. Jackson Soil Science Award (2014), the Award for Outstanding Accomplishments in Research and Creative Activity from UMass Amherst (2015), and the Distinguished Career Award from the Association of Chinese Soil & Plant Scientists in North America (ACSPSNA) in 2012.
Banner Photo from left: Baoshan Xing, PhD candidate Huiyuan Guo, and undergraduate students Lauren Thistle '17 and My Huynh '18.
Karen J. Hayes '85