TRACE ELEMENTS IN THE SOILS OF THE MAN-MADE LANDSCAPES IN PRIMORSKY TERRITORY

Полохин О.В.

ORCID: 0000-0002-5519-5808, кандидат биологических наук, Биолого-почвенный институт ДВО РАН

МИКРОЭЛЕМЕНТЫ В ПОЧВАХ ТЕХНОГЕННЫХ ЛАНДШАФТОВ ПРИМОРСКОГО КРАЯ

Аннотация

Определено содержание микроэлементов в эмбиоземах Павловского угольного разреза Приморского края. Выявлено повышенное содержание Pb, Co, Y, Sc, Zr, но оно не превышает региональное фоновое содержание и имеющихся ПДК, ОДК. Исследованные почвы по содержанию подвижных форм тяжелых металлов, растворимых в 1,0 н. растворе HCl относятся к 1 и 2 группе (низкий уровень загрязненности).

Ключевые слова: микроэлементы, рекультивация, почва, почвообразование.

 

Polokhin O.V.

ORCID: 0000-0002-5519-5808, PhD in Biology, Institute of Biology and Soil Science FEB RAS

TRACE ELEMENTS IN THE SOILS OF THE MAN-MADE LANDSCAPES IN PRIMORSKY TERRITORY

Abstract

The content of trace elements was determined in the young soils in Pavlovsky coal opencast of the Primorsky Territory. Their content in the soils is proved not to exceed the regional background and the existing MPC and APC. The content of Pb, Co, Y, Sc Zr is revealed to exceed its clarke value for the world soils, which is related to the natural origin of this elements. The contents of mobile forms of heavy metals low.

Keywords: trace elements, reclamation, soil, soil formation.

The problem of assessing soil and ecological status of man-made landscapes that form as a result of extraction of minerals is becoming increasingly important. In open-pit mining – the main brown coal extraction method in Primorsky Territory – overburden and inclosing rocks are submitted on the surface. Nonselective stacking leads to chaotic rocks mixing differ in granulometric, petrographic, mineralogical composition. Most of the dumps overgrow in time and are not reclamation. In this regard, specification of microelement composition of forming soils, and concentrations of elements dangerous for human health and environment are necessary in the study course of living conditions in the areas of deposits [5]. Such practice in Primorsky Territory is very rare [2, 3, 4].

Excess level of toxic elements and their compounds in the soil has a depressing and toxic effect on biota. The question of setting a standard of toxic elements level in the soil is difficult and debatable. Same element being a part of different chemical compounds may have different effects on living organisms. Taking into account the highest possible level of hazard, the classes of pollutants according to their hazard degree were developed in Russia (GOST 17.41.02-83): 1 class - high hazard (Hg, Cd, Pb, Zn, As, Se, F); Grade 2 - moderate hazard (Cu, Co, Ni, Mo, Cr, B, Sb); Grade 3 - low hazard (V, W, Mn, Sr, Ba). Heavy granulometric composition and a high level of organic matter lead to soil binding of toxic elements. Redox conditions and the pH level of the soil are equally important. [4]

Study subjects were the soils formed on the 20-years and 30-years-old outer dumps at the Pavlovsky-2 surface coal mine located in Primorsky Territory, 20 km North of the city of Ussuriisk. Open-cast mining of brown coal being used. Geomorphological state of 20-years-old external dump is represented by low ridges and is seen as a technological forming catena [6]. 30-years-old external dump was previously planned and looks like an upland hill 11-15 meters in height (P 8-11). Sampling of transaccumulative (P 1-11) and accumulative (P 2-11) relief feature was carried out at the 20-years-old external dump. The bulk composition of the soil samples was tested using the Shimadzy EDX 800 X-ray fluorescence spectrometer ().

Analysis of soil samples was performed with a Shimadzu EDX-800HS-P instrument (Shimadzu, Japan) equipped with a rhodium X-ray tube. Six certified reference standard samples from the Institute of Applied Physics of Irkutsk State University were used to obtain calibration curves and to assess the analytical recovery and precision.

Mobile forms of elements were tested in 0.1n hydrochlorid-acid extract using the Hitachi-0,5atomic absorption spectrophotometer.

Rock overburden at the Pavlovsky coal mine are represented by the Quaternary clays, alluvial sands and pebble deposits of Suifen suite, argillites, siltstones, consertal sandstones and assorted coal beds of Ust-Davydovskaya suite [10]. Medium reaction – from acidic to slightly acidic. Base saturation 60-85%. Granulometric composition of rocks is heavy, medium and light loamy [7,8].

We carried out the testing of 14 microelements in fine earth soils (embreozems - young soil developing on technogenic ground) of studied dumps. On the basis of the obtained results, we evaluated clarks of elements in relation to the average concentration in sedimentary rocks [1].

Concentration of total forms of elements was compared to the developed MPC for Russia and the MPC for the Far East developed by V.I. Golov [9].

Table 1 ˗ Clarks of microelements in dumps’ soils of the Pavlovsky coal mine

Table 2 ˗ Concentration of mobile elements in man-made landscapes embreozems (mg/kg air-dry material /% of total concentration)

The obtained results show that 20-years-old external dump contains lead (Kk 1.42-1.55) and cobalt (1,20-1,22) in increased amount (in comparison with clarks in sedimentary rocks) (Table 1); 30-years-old The obtained results show that 20-years-old external dump contains lead (Kk 1.42-1.55) and cobalt (1,20-1,22) in increased amount (in comparison with clarks in sedimentary rocks) contains manganese (1.09). In both dumps there is a high concentration of yttrium (3,23-4,02), zirconium (1,15-1,17) and scandium (1.09). In this case, the total concentration of all these elements does not exceed the threshold concentration limits. The remaining microelements are in amounts lower than the national and regional clarks (for the soils of Primorye) in sedimentary rocks.

Studied microelements make the following dependence by the concentration clarks: Y> Pb> Zr> Co> Sc> Mn> Cr> Zn> F> Ba = V> Cu> Ni> Sr.

The most informative indicator of the environmental assessment of soil is the concentration of mobile microelements that can, under certain conditions, move from solid phases of soils to soil solutions and migrate. Table. 2 shows the results of a study of mobile microelements in embreozems of the Pavlovsky surface coal mine.

Studied microelements make the following dependence by the magnitude of the average mobile concentration: Mn> Pb> Cu> Zn> Ni> Co.

Lead with the concentration from 15 to 52% of the total amount has the highest mobility among the highly hazardous elements. The amount of zinc is 20% of the total concentration. The most mobile element from the second class of hazard is copper, up to 30% of the total concentration. The mobility of cobalt, in some cases, goes up to 37%, at average is about 12% of the total element concentration. Manganese has the highest mobility, the third class of hazard, up to 68% of the total concentration.

In general, we can say that soils in man-made landscapes of the Pavlovsky surface coal mine are formed on rocks with low health and toxicological hazard. Given the short period of soil formation and regeneration in the dumps, we can assume that these formations will not pose a serious threat to the environment in future.

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