# Influence of Phosphogypsum Dump on the Soil Ecosystem in the Sumy region (Ukraine)
## 2 Materials and Methods
### Methods of Investigation  
Fourier Transform infrared spectrophotometry (FTIR) measurements of phosphogypsum and soil samples were carried out on a Bruker Alpha Platinum-Attenuated Total Reflection (ATR) spectrometer (Bruker Optics, Ettingen, Germany). A total of 24 scans were performed on each sample in the range of 4000-400 cm\({}^{-1}\).  
The basic chemical composition of phosphogypsum and soil samples was determined by X-ray fluorescence analysis (XRF). A SPECTRO iQ II (Ametek, Berlin, Germany) operating with a silicon drift detector (SDD; resolution of 145 eV at 10,000 pulses) was used.  
Mineralogical analyses of the samples were carried out by X-ray diffraction (XRD) using a diffractometer Bruker D2 Phaser (Bruker AXS, GmbH, Germany) in Bragg-Brentano geometry (configuration Theta-2 Theta), using 1.54060 A CuK\(\alpha\) radiation, Ni K\(\beta\) filters, and a scintillation detector at a voltage of 30 kV and 10 mA current. Scan conditions: recording time of about 2.5 h, a step size of 0.04\({}^{\circ}\) (2\(\Theta\)), and step time of 5 s. The XRD patterns were processed using the software Diffrac.EVA v. 2.1. The International Centre for Diffraction Data (ICDD) Powder Diffraction File (PDF) database (ICDD PDF--2 Release 2009) was utilized for the phase identification. The pH was analyzed by pX-150 pX-meter (ionometer).  
Field research was carried out on the previously planned routes, which specify the boundaries of the contours of plant communities for description of photocenoses in the territory of the phosphogypsum dump. The cenopopulation (CP) of any plant is a historical and dynamic phenomenon that constantly changes and develops. The CP is a set of individuals of the species within the same phytocenosis, occupying a specific habitat.  
The study of CPs occurred in accordance with the standard method described in [27]. All dimensional and quantitative characteristics of plants in a CP vary over a wide range. Indices of a CP, such as total number and density, phytomass, area occupied by the population, projective cover, and age spectrum, are subject to change. The number of a CP is determined by the number of generative individuals and their shoots, potential and real seeds, vegetative productivity, diaspora stock in the soil, seed germination, and survival rate of undergrowth. Seed productivity, real and potential, can vary markedly in different age conditions and over time, depending on weather conditions, the impact of phytophages, etc. In most meadow plants, seed regeneration is limited by the survival rate of seedlings.  
Therefore, the analyses of the structure of the CP are a complex formation consisting of several categories [27]:  
- composition;  
- quantitative participation and the ratio of elements with different properties;  
- spatial structure;  
- mutual arrangement of plants in space;  
- functional structure;  
- a set of links between the elements, as well as between the system and the environment.  
Fluctuations in the number of seedlings in a CP are significant both during the season and over a span of years, and numbers range from 1-2 to 100-1000 per m\({}^{2}\). An indicator of dynamic processes can be a change in the age spectrum of a CP. The populations of different species have different degrees of dynamism: (1) Population waves move gradually, while the type of age spectrum does not change and remains full-term. This occurs with regular, but relatively small, replenishment of young individuals. (2) Population waves move quickly, and the age spectrum can be broken and incomplete. The great liability of all population indicators is characteristic of pioneering plants, capable of very quickly capturing vacant areas, but also freeing them when crowded out by competitive species. Various transitions are distinguished between these two types of dynamics.