On April 15-16, 2021, the 2021 Stable Isotope Measurement Technology and Application Academic Exchange Conference hosted by the State Key Laboratory of Earth Surface Processes and Resource Ecology of Beijing Normal University and co-organized by ABB of Canada and LICA of China was successfully held online.
From Tsinghua University, Peking University, Beijing Normal University, Chinese Academy of Forestry, Chinese Academy of Sciences, China Agricultural University, Beijing Forestry University, Northeast Normal University, Shenzhen University, Southwest University, Nanjing University of Information Technology, Zhejiang University, Fudan University, Nankai University Experts, scholars and business personnel from more than 100 units including Tongji University, Xinjiang University, Northwest A&F University, Mainz University, Madrid Polytechnic University, etc. participated in the conference. The number of visits in the live broadcast room reached more than 3.5W in two days.
The theme of this exchange meeting is: Research progress in comprehensive monitoring of surface processes based on stable isotope technology. The purpose is to carry out technical exchanges and training focusing on the basic theories of stable isotope, technical methods, data analysis and comprehensive monitoring of surface processes and other aspects for scientific research personnel, and promote and popularize the application of stable isotope technology in different fields.
This seminar is divided into two parts: expert report and technical training.
The meeting began at 9:00 on April 15th, and General Manager Sun Baoyu of LICA delivered an opening speech for the meeting, welcoming the teachers who came to the meeting and wishing the seminar a complete success.
In the morning report, Professor Lin Guanghui of Tsinghua University, Professor Bai E of Northeast Normal University, Professor Song Xin of Shenzhen University, and General Manager Sun Baoyu of LICA respectively introduced:
Some new developments in stable isotope ecology and its applications;
Using stable nitrogen isotopes to study forest nitrogen cycle;
Study on the fractionation effect of plant water and cellulose oxygen and hydrogen isotope;
Research progress on new technologies and application practices of ecosystem monitoring.
In the afternoon report, Associate Professor Wang Pei from Beijing Normal University, Professor Yu Xinxiao from Beijing Forestry University, Professor Xinhua He from Southwest University, Dr. Frederic Despagne from ABB LGR, Senior Engineer Yang Lihu from the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, China Researcher Xu Qing from the Academy of Forestry respectively introduced:
Observation and tracing research of leaf water isotope in vegetation canopy;
Research on vegetation water and carbon process based on stable isotope technology;
Field in-situ 13C/15N double labeling experiment technology and carbon and nitrogen cycle tracking;
Applications of ABB LGR-ICOS stable isotope analyzers in ecology;
Application of isotope technology in hydrology and water resources;
Application of stable isotopes in the study of plant water use in terrestrial ecosystems.
On the morning of April 16, researcher Wen Xuefa from the Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Associate Researcher Sun Shoujia, Chinese Academy of Forestry, Professor Xiao Wei from Nanjing University of Information Technology, Professor Wu Xiuchen from Beijing Normal University, and Zhao Ni, an application engineer from LICA, respectively introduced Up:
Application of isotope technology in ecosystem ecology;
Application of stable carbon isotopes in ecological research;
Study the contribution of the surface to atmospheric water vapor based on the stable isotope method;
The impact of snow cover on the growth of forests in northern China;
The application of laser isotope measurement technology in the water carbon and nitrogen cycle of ecosystems.
On the afternoon of the 16th, the technical engineer Du Wensheng from LICA gave detailed operation training to the ABB LGR water isotope analyzer and the LI-2100 automatic vacuum condensation extraction system.
This exchange will make full use of the Internet platform and adopt the form of online live broadcast. Teachers can quickly answer questions by sharing screens, voice and text dialogues. During the training, everyone attentively listened to the lectures, faced with the difficulties, and actively participated in online communication. The learning atmosphere was good and the interaction was enthusiastic.
After the live broadcast ended, some students still asked questions in the live broadcast room and hoped to communicate with the teachers. We hereby collect related questions raised in the live broadcast room, as follows, thank you teachers for your patience.
Professor Bai E's Q&A
Q: May I ask Professor Bai E, what is the difference between zero tension and suction to obtain the source of the soil solution? Thank you.
A: The difference between the source of the soil solution obtained by zero tension and suction: This problem will be more clear to my colleagues in soil water. Zero tension is water leakage, which is what we call leaching. The suction sampling meter is pore water, and the collected water may not necessarily be able to be leached out. But sometimes there are very few samples collected at zero tension. In order to better understand the soil water, suction is used instead.
Q: Professor Bai E, hello, in the process of biodegradation of organic matter, more nitrogen needs to be added to degrade the organic matter. I want to know the whereabouts of nitrogen in the process of organic matter degradation. At this time, I can add N15. Is there more? Or can I add a small amount of labeled 15N and more unlabeled nitrogen? Thank you teacher.
A: In the case where the 15N abundance of the final product is very high, but the amount of N15 added is not enough to degrade the organic matter, I think it can degrade the organic matter and know the whereabouts of the nitrogen. I think it is possible to mix a large amount of unmarked nitrogen The 15N-labeled nitrogen source with a small source and amount is added after reaching the used amount. Only when calculating it, don’t make a mistake.
Q: Is there a specific numerical relationship between the isotope of predator and the isotope of prey by Professor Bai E?
A: The isotope of the predator is generally related to the isotope of the prey. The most important factor determining the isotope of an organism is its source. For example, the nitrogen of the prey is the source of the nitrogen of the predator, but the specific ratio depends on the ratio. If there are many other Source, and the proportion of this prey is small, the relationship is weak. If the predator only relies on this single source, there should be a strong correlation.
Q: Professor Bai E, hello. In the experiment you talked about Part1. The whereabouts of sedimentation nitrogen, are ammonium nitrogen and nitrate nitrogen added to different soils separately, or are they added to the same soil at the same time? If it is added to the same soil, then in a series of conversion processes of ammonium nitrogen and nitrate nitrogen, will there be a situation where N15 in ammonium nitrogen will run into the nitrate base? This should affect the nitrate The measurement of nitrogen and ammonium nitrogen, right?
A: Part1. The whereabouts of deposited nitrogen In this experiment, ammonium nitrogen and nitrate nitrogen were added to different soils. You cannot add to a sample at the same time, you are right.
Professor Song Xin Q&A
Q: Thank you Professor Song Xin for his wonderful report. There are two questions for you: 1. Do you want to peel the branches used for extraction? I think your PNAS article did not mention this clearly. Personally, I feel that peeling has a considerable impact on the extraction results; 2. You challenged the 'two water worlds' to a certain extent through the exchange of organic matter H and xylem water. ', have you considered the influence of the heterogeneity of the isotopic composition of different parts of the whole plant and the heterogeneity of the isotopic composition of the soil moisture (such as different pore sizes) on your overall results, thank you.
A: Very good question. 1) It is peeled, and it is actually mentioned in the method of the article; 2) This problem is very important. There is also potential fractionation in the process of soil water vacuum extraction, and the mechanism is relatively complicated. Many researchers are doing research in this area. Our control experiment uses sandy soil (we even considered hydroponics, so that we can clearly know the value of the real source water), because according to previous studies, the fractionation effect of sandy soil is almost negligible. Our paper is aimed at soil Discussion on the complexity of fractionation; another difference in isotopic composition of different parts of plants, - here is the branch water or leaf water? The difference in isotopic composition of different parts of plants, I thought about it, it doesn’t matter much in our experimental system. One is that we use small saplings and the canopy is relatively simple. In addition, the air in the chamber is fully mixed and there is no microclimate like in the wild. In addition, our sampling site is the main stem, not the side branches, and the main stem is wrapped with aluminum foil to prevent transpiration and enrichment. However, the situation in the field is much more complicated, and within-plant isotope heterogeneity is indeed a problem that needs attention.
Q: I would like to ask Professor Song Xin, does this kind of hydrogen isotope depletion change due to different growth periods and seasonal changes of plants? Will it change with time and space, or will there be a constant offset?
A: Very good question. The answer is not yet clear, and this question deserves to be better revealed through further data accumulation. According to the results that we found that the degree of depletion and the water content of the branches have a good correlation, if the spatiotemporal changes are accompanied by changes in the water content of the branches (for example, the water content of the branches in the dry season may be lower?), then the degree of depletion should also be There are differences, but the magnitude of the difference is not to be said. Generally speaking, the difference in water content of branches is greater between species than within species, so the degree of depletion should also be greater between species than within species?