Soil sampler invented at XJTLU could promote food safety

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Scientists at Xi’an Jiaotong-Liverpool University have invented a unique soil solution sampling tool that could help ensure the safety of food grown on land once polluted by harmful heavy metals.

Dr Zheng Chen from XJTLU’s Department of Health and Environmental Sciences says the new tool could monitor soil contamination risks in the agriculture industry.

“A large amount of agricultural land worldwide is contaminated by heavy metals that can be harmful to people’s health, so engineers are trying to design methods to grow crops on these lands safely,” he says.

“If they were able to predict how a concentration of heavy metals in soil is linked to a concentration of heavy metals in the edible part of a plant, they could devise better ways to manage the soil. We hope our device can help them make that prediction.”

In addition to promoting food safety, he and his team believe the tool could aid farmers in growing crops more efficiently.

“We think this tool could be used to help farmers more accurately apply fertiliser by measuring nutrients in the soil around plant roots,” he says.

“While these uses for agriculture would need to be tested, we believe the tool has a number of applications which could lead to more efficient, environmentally-friendly practices.”

According to Dr Chen, the device is currently the best available to study distribution of heavy metals in flooded soils.

“Other tools easily disturb the soil being tested or cannot analyse the soil with the detail required in certain situations,” he says.

“Our tool has minimal risk for disturbing the soil, and can analyse a sampling zone at high resolutions – about two millimetres compared to the more-than-a-centimetre resolution offered by the previous method.

“Furthermore, our device can be used repeatedly and can measure changes over time.

“We might be the only group in the world who can measure heavy metals in high resolution at different time points.”

The tool is currently being tested at Zhejiang University – the first use outside of XJTLU. Dr Chen (pictured above) says he hopes other scientists doing related research will also try it, which could lead to an expansion of its uses.

The tool features a tube made of special plastic that is inserted into the soil. The tube’s surface is porous, with holes so small that large molecules or soil particles cannot pass through. However, the holes are large enough that heavy metal ions and small molecules can enter.

“When we bury the tube in soil and fill it with oxygen-free pure water, the heavy metals diffuse into the tube,” Dr Chen says.

“The solution inside the tube with the target chemicals can then be taken out and analysed. This process can be repeated.”

“When retrieving the sample or setting up the tool to collect another sample from the same location, we don’t need to touch the soil.”

“In addition to being able to collect samples from the same location at different times, we can also collect samples close to each other but at different depths by assembling samplers together.”

Interdepartmental collaboration at XJTLU helped make the tool a reality, Dr Chen notes. The researchers enlisted help from the Department of Industrial Design to create the soil sampler.

“We came up with the idea, but we did not have the skills to make the prototype,” he says.

“Yang Zou, an undergraduate student from the Department of Industrial Design, used a 3D printer to build the model.”

The patent-pending tool was recently introduced to other scientists through an article in the journal Environmental Science and Technology.

By Tamara Kaup

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