# Influence of Phosphogypsum Dump on the Soil Ecosystem in the Sumy region (Ukraine)
## 3 Results and Discussion
### The Study of Biochemical Transformations of the Technogenic Array of Phosphogypsum
On old, reclaimed loans and slopes of the canopy, the projective covering of the herbaceous perennial vegetation is complete; on the lowest terrace, apart from the grassy annual and perennial vegetation, young trees have started to settle, which indicates the slow progressive succession changes in plant groups. [PERSON] et al. [37] reported that changes in plant communities are based on their visibility, and plants are usually used to predict the success of the restoration of degraded environments. On the three lower slopes of the heap, the projective covering of the vegetation is as complete as possible; in the upper part of the terraces, especially of those recently subjected to reclamation, the quantity and species diversity of plants decreases. The annual and perennial herbaceous plants are dominant on the reclaimed slopes of the phosphogypsum dump of the PJSC \"Sumykhimprom\" (Table 4). On the lower terraces (third and fourth), tree forms have begun to settle, represented mainly by _Populus tremula_, _Populus alba_, _Betula pendula_, and _Robinia pseudoacacia_. The stage of the formation of a permanent herbaceous cover with a full projection of the substrate coating lasts at least a decade for extreme substrates, including phosphogypsum. The acidity of the environment affects the plant growth and species dominance, and this effect is limited by a number of factors:  
* the features of the technogenic relief of the dump;
* the high concentration of certain chemical elements (calcium);
* the inconstant availability of water;
* a small length along the depth of the re \begin{table}
\begin{tabular}{c c} \hline \hline
**Named Family of Plants** & **Representatives** \\ \hline \hline \multirow{6}{*}{Gramineae} & _Calamagrostis epigeios_ \\  & _Elytrigia repens_ \\  & _Echinochla crusgalli_ \\  & _Selaria viridis_ \\  & _Poa amua_ \\  & _Lotus corniculatus_ \\  & _Trifolium pratense_ \\  & _Trifolium repens_ \\  & _Trifolium ocroleucum_ \\  & _Melitotus officinalisis_ \\  & _Tussilago farfara_ \\  & _Erigreen canadensis_ \\  & _Achillie millifolium_ \\  & _Erigreen anntus_ \\  & _Tanactum vulgar_ \\  & _Artemisia vulgaris_ \\  & _Sonchus arrenisis_ \\  & _Cirsium arrense_ \\  & _Polygonaceae_ \\  & _Onagracae_ \\  & _Onagra biennis_ \\  & _Linait vulgaris_ \\  & _Salicaceae_ \\  & _Populus tremula_ \\  & _Betula pendula_ \\  & _Loguminosae_ \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Herbaceous plants that dominate the reclaimed slopes of the phosphogypsum dump of PJSC “Sumykhimprom”. The formation of tree stands was observed mainly 20 years after dumping. This process of self-growth is affected by the high acidity of the substrate and the high concentration of chemical elements, which is mainly determined by the intake of chemical elements and their compounds from the dump [34]. Figure 11 shows a general diagram of the process of self-growth vegetation in the dump. The degree of projective coverage on the terrace 4 is almost 95%, then it decreases on terrace 3 (75%), terrace 2 (45%), and terrace 1 (5%). The upper deck is fully open, without vegetation. This trend in the blade covering depends on the arrival of new lots of fresh phosphogypsum, which contributes to the uneven distribution of vegetation. Thus, terrace 4 is the most reclaimed. A substrate is formed, which is to be populated with living organisms, primarily microorganisms and plants [35; 38]. According to [PERSON] [39] and [PERSON] et al. [40], microorganisms carry out the transformation (oxidation, reduction) of a number of inorganic compounds of the substrate, including mineral particles of phosphogypsum, transferring their components more or less conversely, depending on the conditions (pH, Eh). The roots of plants gradually settle on the surface of the substrate of the dump and absorb substances directly from the soil solution and in contact with the particles of the soil-absorbing complex.