The basin of lake Khubsugul has not yet been affected by human influence (75% of endemics in ecosystem) and can serve to recreate and decoding of the model of the standard' nature system.
A comprehensive study of ecological functioning features of the soils, formed on outputs of phosphorites' layers of Ongolignur deposit of Khubsugul phosphorite basin of Baikal rift zone was conducted. It was found that the soil formation, biogeochemical migration of phosphorus and other elements, the humus state of soils and biological productivity of biocenosises of the study area is strongly determined by the influence of lithogenic basis of soil, intrazonal factors and cryogenesis.
Phosphate-carbonate lithogenic basis (matrix) of phosphorite soils, forming a strong organic-mineral frame of humate composition, helps to support a sufficiently high level of soil-ecological potential of the study area.
Weathering of phosphate-bearing soil-forming rocks of the deposit leads to a significant accumulation of silicate fine-thin aleurolite compounds as the decomposition and carrying out of carbonate component, and also - contributes to the residual accumulation of clay minerals and silty organic matter. Carbonates are “hiding” the impact of phosphate material of parent rocks for soil genesis, promoting to the formation of hydro-mica-chlorite-illite composition of the clay’ part of soils with signs of weak crystallization and super-dispersion’ fineness of illites. Phosphorite soils are characterized by a large quantity of total (up to 3% P2O5) and mobile phosphorus, which determines their peculiar morphological and physico-chemical properties. Phosphorus and carbonates are promoted to the stabilization of the humus accumulation process at the studied soils through the coagulation of solid carbonate-phosphorus-humus complexes, the mineralization of which has been inhibited by the formation of protective thin carbonate layer on them. Fractional analysis of mineral phosphates showed that under the influence of phosphorite layers clay substances and phosphates of Al and Fe are most active accumulated in the studied soil profiles,forming complexes with humus substances.
The lithogenic matrix determine the directions of soil formation because of its bioclimatic «reflectivity», forming a lithogenic spectrum of soils on rocks with different content of carbonate and phosphate, complicated of stratigraphic and facies variability of phosphate-(siliceous)-carbonate rocks. Carbonate barrier creates unfavorable conditions for growth of areas of distribution of phosphate dispersion and non-stability of phosphorite-soils in case of possible industrial mining and disintegration of the rocks of deposit.
In the landscapes surrounding lake Khubsugul, in addition to CA-P classes of soils and landscapes there are other "exotic", due to the presence of fluorine, polymetals, iron, copper and other chemical elements. Vanadium, nickel,fluorine, mercury are the elements with a high content in the environment of the Khubsugul phosphorite deposit, that can be accumulated in the trophic cycles.They are "transformers", which can lead to individual genetic disorders in biota.
Of the elements, which are typomorphic to the Khubsugul deposit, mercury belongs to the first class of the sanitary hygienic danger, but its anomalies are local and low-contrast; fluorine – belongs to second class (with large areas); phosphorus is a biogenic element. These data make it possible to formally classify the Khubsugul deposit as an ecologically average dangerous one.
If we take into account the contrasting natural and anthropogenic situation, the Khubsugul deposit should be attributed to the first class of danger, which is determined by the impact on the biota of landscapes with phosphorus-manganese specialization (which leads to increasing incidence of “urolithiasis”), and by influence of very large amounts of overburden rocks of the deposit.
During the open mining of the phosphorite deposit, there is possible to activate of naturally balanced system of Khubsugul depression with an increase of pollutants over long distances along the wind rose. Phosphorus can be involved in the biological cycle and in the form of phosphorus-organic compounds can migrate across the landscape, promoting to the phosphatization of lake Khubsugul. The open mining of the deposit will can bring eutrophication to part or all area of lake Khubsugul (and, possible,of lake Baikal). Hydrogen sulfide contamination of the lake will require of “geological” periods of time for restoration of it current ultra-oligotrophy.
Conducted researches of phosphorite soils confirm of necessity of preservation of these exotic unique landscapes of the Baikal rift zone, which have no analogues within Siberia and Mongolia.
|Publication||Journal of Cleaner Production|
|Affiliation of speaker||Department of soil science and land resources assessment, Irkutsk State University , faculty of biology and soil science|
|Position of speaker||senior lecturer|