Prof.  Irina  Shtangeeva
Institute of Earth Sciences, St. Petersburg State University,  Russia

Title: Factors influencing the results of field and greenhouse experiments at the stages of collection and analysis of plant and soil samples

Abstract:

Keywords: plants, soil, sampling, preparation for analysis, analytical techniques 

Sampling of plants and rhizosphere soil is one of the most important stages of environmental analysis. Errors made during this procedure can seriously influence the quality of the experimental results. Especially this concerns field trials when number of factors affecting the concentration of different organic and mineral components in environmental samples is usually rather high. It is important to remember that various external factors, such as temperature, humidity, ozone and nitric acid levels in ground air, the geomagnetic field, and many others, change over a short period of time (hours) even in a small area. An additional factor, often overlooked by researchers, is the circadian fluctuations of organic compounds, macro- and trace elements in both plants and rhizosphere soil, the condition of which is closely linked to the functioning of plant roots.

Preparing samples for elemental analysis is another important procedure that also can affect the experimental results. It is clear that plants should be cleaned before analysis to remove from the surface of leaves and especially root surface small particles of soil and dust. This operation should be carried out as soon as possible after harvesting. On the one hand, there is a certain risk that in the course of washing a small part of mobile elements may be lost. But if we conduct an elemental analysis of unwashed plant samples, we will determine not only the composition of the plant itself, but also the dust on its surface, and its contribution can be quite significant. Gentle methods should also be used to dry plant and soil samples. The samples can be dried till constant weight under room temperature. Drying at higher temperatures may result in the loss of some volatile elements.

Most part of routine analytical methods used for elemental analysis of environmental samples, including ICP techniques, requires dissolution of solid samples (soils and plants) in acids. Such sample processing, like any additional operation in the process of elemental analysis, may lead to some errors. To reduce this risk, it is necessary to seek methods that allow the analysis of samples in their natural state. Among others, instrumental neutron activation analysis is very promising analytical technique. In this case, the determination of more than 30 macro-nutrients, trace and ultratrace elements in various environmental samples can be performed with high sensitivity and accuracy without any pre-treatment of samples before analysis. Raman spectroscopy is another promising analytical technique that allows the determining various organic compounds in small samples without special pre-treatment of environmental samples before analysis.

This paper will present the results of recent field and greenhouse experiments and describe in detail the experimental design and sampling procedures, taking into account, first of all, the reasons for possible short-term changes in the elemental composition of various environmental samples.

 

Biography:

Affiliation and work address:
Institute of Earth Sciences, St. Petersburg State University, Universitetskaya nab., 7/9, St. Petersburg 199034 Russia, Tel: 007 812 687-61-22, E-mail: shtangeeva@gmail.com

Career/Employment:
2014 – senior researcher,InstituteofEarth Sciences,St. PetersburgUniversity
2006 – 2014 senior researcher, Chemical Department,St. PetersburgUniversity
1999 - 2006 - senior researcher,InterdisciplinaryCenter,St. PetersburgUniversity
1991 -1999 - senior researcher,InstituteofEarth Crust,St. PetersburgUniversity
1983 -1991 - researcher,InstituteofEarth Crust,St. PetersburgUniversity
1979 -1983 - junior research scientist,InstituteofEarth Crust,St. PetersburgUniversity
1978 -1979 - engineer,InstituteofEarth Crust,St. PetersburgUniversity

Main scientific interests:
Ecology, biogeochemistry, multivariate statistics and modelling, modern analytical techniques