**4. Conclusion**

(casts on bulk humic layer from ordinary chernozem in the plantings of Norway maple). This, apparently, is due to the fact that the casts formed on loess-like loam is represented by the soilforming rock that contain no organic matter (particularly humus), while the earthworm casts that formed on filling humic layer includes soil organic matter. Furthermore, the presence of humic compositions in earthworm casts is a powerful factor in process of stability formation

In the context of soil-casts system, effect of casts (Sref – Ssamp) on copper immobilization within concentration range of Cu from 50 to 400 mg is more than the effect of initial bulk soil (respectively 170.6 and 197.5 area units on the second variant with humus-free loess-like loam; 343.7 and 373.4 area units on the third variant with humic layer of ordinary chernozem). In both cases, difference between average effects was statistically significant; values of significance

Efficiency of immobilization in the studied casts (humus-free and humic variants) was more (23 and 43%, respectively) than the efficiency of immobilization in the initial soil: loess-like loam and chernozem (19.9 and 40.1% respectively, see **Table 1**). Efficiency of copper immobilization by casts compared with the corresponding initial soil (variants with loess-like loam and ordinary chernozem coating) was more by 3.1% (the difference between 23 and 19.9%) and 3.5%, respectively (the difference between 43.6 and 40.1%). It evidences for the positive environment-forming role of earthworms (particularly their tropho-metabolic activity) in development of protective and buffer shield of remediated soils and enhances the immobilization ability of the zoogenic soil neoformations—casts—within sites of forest remediation. Thus, earthworm tropho-metabolic activity within different variants of forest remediation sites affects the soil immobilization capacity maintenance (buffering capacity to heavy metals,

> **Loess-like loam, second variant**

0.0011 0.0012 –

**Table 2.** Statistical evaluation of differences between effects of earthworm cast and bulk soil against copper

0.0006 0.0009 0.045 –

**Casts (humic layer of ordinary Chernozem, third variant)** 

**Humic layer of ordinary**

**Chernozem, third**

**variant)**

in remediated soil against the effects of toxic concentrations of copper.

level were 0.03 and 0.045, respectively (**Table 2**).

284 Soil Contamination - Current Consequences and Further Solutions

**Item Casts (loess-like**

Loess-like loam, second variant 0.03\* –

*Note*: The table shows significance level to compare pairs of objects.

**loam, second variant)** 

–

including copper).

Casts (Loess-like loam, second

Casts (humic layer of ordinary Chernozem, third variant)

Humic layer of Ordinary Chernozem,

variant)

third variant)

contamination.

Ecosystem effectiveness of vital activity of soil saprophages (earthworms, *Lumbricidae*) was shown to be effected for increasing of buffering capacity in remediated soil against copper contamination. Resistance from concentrations of copper was increased in casts within the following range: from humus-free loess-like loam to humic layer of ordinary chernozem.

Effectiveness of copper immobilization by earthworm casts increased from 3.1 to 3.5% in comparison with the initial remediated soil. Thus, efficiency of process of land remediation increases with enrichment by earthworm casts; it leads to improvement of ecological quality in remediated soil. Earthworm ecoservice activity changes positively environmental features of remediated soil and speed up naturalization of artificial edaphotopes within remediated lands in steppe zone.
