用价值1美元的工具对抗空气污染

The new tool is so simple that it could easily be mistaken for a grade-school science project. The chamber is made by removing the bottom of a large soda bottle and attaching it to the open bottle top. This shields a thin strip of foam that runs along the inside of the bottle from the mouth down to a small plastic cup anchored to the soil with three metal prongs. This foam is presoaked in an acid solution that traps ammonia. The chamber is placed alongside the plants or livestock area to be monitored, and the foam is removed every 24 hours and taken to the laboratory for analysis.

This unique and simple device and instructions on how to use it were created by scientists from the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, EMBRAPA and Brazil’s Agronomic Institute of Parana (IAPAR).

“This device could help us understand ammonia losses and move toward climate-smart solutions that leave enough nitrogen to boost plant productivity, especially in less fertile and nitrogen-deficient soil, which can have a major impact on food production,” said Mohammad Zaman, a soil scientist and plant nutritionist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.

The device can be used on its own to precisely measure ammonia losses, as well as in combination with agricultural practices designed to reduce greenhouse gas emissions and their impact on the environment. These practices include drip irrigation systems, co-application of fertilizers with nitrogen process inhibitors and crop rotation involving nitrogen-fixing legumes.

A major concern with such a simple setup was the reliability of its results. To test this, the scientists used an isotopic technique that involves adding nitrogen-15 to fertilizer (see The Science box) as a way to track, measure and compare the amounts of ammonia captured by the plastic chamber versus how much ammonia was released, which was determined by using the nitrogen mass balance method to check the amount of nitrogen in the soil over time. As ammonia is a compound containing nitrogen, the nitrogen-15 method allows scientists to track the ammonia losses.

The results of the tests showed that the chamber was reliable and suitable for tracking ammonia emissions from organic and synthetic fertilizers used for annual and perennial crops, as well as for excreta in livestock systems. “This method is highly efficient and precise in measuring and monitoring ammonia in comparison to the traditional closed chamber method,” Urquiaga said.

Experts in six countries — Brazil, Chile, Costa Rica, Ethiopia, Iran and Pakistan — have already started using the tool. More widespread use of the tool is expected, said Zaman, with the foreseen publication of the project results in a special edition of a peer-reviewed international scientific journal, as well as with a plan to recommend to the Intergovernmental Panel on Climate Change (IPCC) to include the tool as a method for use in agricultural systems worldwide, especially in developing countries.