On 16 December, the Workshop on the application of the tagged neutrons method in ecology took place in a hybrid format in the JINR Scientists’ Club. Participants focused their attention on the opportunities opened up by this method in measuring the carbon content in soils. The soil is one of the most important carbon reservoirs, so such measurements, the increase in their speed are getting increasingly relevant in the global environmental agenda.

A project on the creation of a carbon polygons network has started in Russia. These are special territories allocated for the development of technologies to increase the carbon storage in various natural reservoirs, as well as of devices and technologies for monitoring emissions and absorption of greenhouse gases. Representatives of carbon polygons, which have already opened or are planned for the launch, as well as specialists in ecology and soil science, took part in the Workshop.

The tagged neutrons method (TNM) meets many expectations from new methods of measurements in ecological studies:

• it has a considerable potential to increase efficiency, i.e. to increase the monitoring coverage;
• it does not require sample preparation;
• it can provide information about layers of the soil without extracting samples;
• it is potentially able to determine soil moisture and density, or measure the content of carbon in a corresponding layer per unit area;
• the TNM-based device can be mobile;
• the soil analysis is carried out fairly fast.

Head of the FLNP Sector of Research on Neutron and Nuclear Interactions, Head of the TANGRA project Yuri Kopach presented the essence of the method. He said that since 2014, the TANGRA project has been developed at JINR. It is a facility based on the tagged neutrons method. The key aim of the project is fundamental research. However, the method itself is used in various applied fields. Thus, commercial facilities based on the TNM are successfully used for detecting explosives and drugs, as well as for non-destructive analysis of rocks.

“We have studied the relevant literature and found out that for more than 10 years, there have been attempts to use this method to determine the carbon content in soils using this method. At first glance, it has some advantages for such activities,” Yuri Kopach said. “Nowadays, soil scientists mainly use the chemical analysis of soil samples. A rather time-consuming procedure of sample collection and preparation precedes it… The TNM vice versa can be used for fast analysis without taking samples. But of course, it is clear that evaluation of real opportunities provided by the method, particular scenarios of its use, and, subsequently, the development of methodical issues are only possible in partnership with specialists. At the same time, it is necessary to proceed from the TNM peculiarities: if the chemical analysis requires collecting small samples from various areas of the studied territory, then an average value for a significant physical volume is analysed when using the TNM-based devices. Neutrons penetrate to a depth of 150 cm, but the real analysed volume is the layer of about 30-50 cm deep with an area of 40×40 cm. Or just separate layers, for example, 0-10 cm and 10-20 cm.”

Participants discussed the proximal analysis methods. In particular, the Coordinator of the SMART URBAN NATURE research centre Vyacheslav Vasenev reported on the use of compact devices for the X-ray fluorescent analysis used nowadays by specialists in the fields of pedometry. According to the speaker, one of the options for the appearance of the “field” analytics platform is a mobile mini-laboratory uniting the opportunities of several analysis methods.

Head of the Sector of Neutron Activation Analysis and Applied Research of FLNP JINR Inga Zinicovscaia spoke about the experience and opportunities of the Sector to participate in ecological and agricultural projects. She exemplified it with the results of the content analysis of chemical elements, including heavy metals, in soils of Moldova and in the agricultural products grown on them.

She noted that the neutron activation analysis (NAA) can determine up to 45 elements of the Periodic Table. “The NAA method is a highly accurate qualitative non-destructive (samples are not dissolved) method that does not require any sample preparation,” she said. “We cannot create a mobile device based on it, but I am convinced that our opportunities may be a topical addition to other analysis methods used in ecological studies.”

Albina Akhunova and Egor Razinkov (the TANGRA collaboration, on behalf of Diamant LLC) shared the details of the appearance of the device for determining the carbon contents in soils based on the TNM. A. I. Akhunova spoke about the experience in the TNM use for measuring carbon in soils by research groups in the USA. E. A. Razinkov presented the original results of measurements of carbon in soils in bench tests conducted at JINR, as well as using the prototype of a TNM-based mobile facility at the carbon polygon in Kaluga region, Russia.

Participants of the event summed up the results of the Workshop at the round table. They discussed a number of fundamental issues. Specialists noted the necessity in determining correctly the accuracy and sensitivity of the method comparing its results to the results of already tested methods, for example, the chemical analysis. Other parameters of the method, scenarios of its application, including, for example, taking into account vegetation, its root system, soil composition features, etc. also require clarification.

Participants noted that it is necessary to solve the issue of evaluating the content of organic carbon. Some ways to solve it were proposed, like using the TNM in combination with other methods, the implementation of special scenarios of its use, for example, in conditions when the mineral fraction may be considered sufficiently stable with considerable organic dynamics.

The key milestone of the Workshop is the marked interest of possible users in the TNM methodology and the facility being created. Thus, the mobile/field facility of the TANGRA project has drawn the attention of specialists in the fields of carbon polygons. They are keen on fast carbon measurements in various soil layers in the conditions of a polygon/expedition. Moreover, according to the experts in the fields of natural resource management speaking at the Workshop, the opportunities of the tagged neutrons method are of great interest in the light of the current development of agriculture in Russia.

Participants of the event have agreed upon the development of the first practical steps. They are drafting the programme and methodology of joint experiments, scenarios of using the TNM for carbon polygons and ecological studies.

Read about event in JINR Weekly Newspaper