Trophic-metabolic activity of earthworms (Lumbricidae) as a zoogenic factor of maintaining reclaimed soils’ resistance to copper contamination
Soil contamination by heavy metals, first of all, influences biological and ecological conditions, and it is able to change the conservative soil features, such as humus content, aggregation, acidity and others, leading to partial or total diminishing of soil fertility and decrease in soil economic value. Zoogenic issues of soil protective capacity formation in conditions of heavy metal content rise under technogenesis have been studied. The article discusses the features of earthworm trophic-metabolic activity in the afforested remediated site (Western Donbass, Ukraine) with different options of mixed soil bulk. Western Donbass is the large center of coal mining located in South-Western part of Ukraine. High rates of technical development in this region lead to surface subsidence, rising and outbreak of high-mineralized groundwater, and formation of dump pits of mine wastes. Remediated area is represented by the basement of mine wastes covered by 5 options of artificial mixed soil with different depth of horizons. The following tree species were planted on top of artificial soil: Acer platanoides L., Robinia pseudoacacia L., and Juniperus virginiana L. The main practical tasks were to define on the quantitative basis the buffer capacity of artificial mixed soil and earthworm excreta in relation to copper contamination and to compare its immobilization capacity in conditions of artificial forest plants in the territory of Western Donbass. It was proved that earthworm excreta had a great influence on soil immobilization capacity (particularly, on soil buffering to copper) which increased for excreta in the following range: humus-free loess loam - top humus layer of ordinary chernozem. Immobilization efficiency of copper by earthworm excreta from ordinary chernozem bulk compared with baseline (ordinary chernozem) was significantly higher. It should be noted that trophic-metabolic activity of earthworms plays very important role as a zoogenic factor which restricts movement of excess chemicals, maintains stability and increases resistance to soil contamination, in particular, with copper. Besides, it is possible to accelerate the artificial forest edaphotop naturalization on reclaimed land, and to increase its ecological value.