D:\CSD 4 (2008)\Kashin.P65
Total Page:16
File Type:pdf, Size:1020Kb
Chemistry for Sustainable Development 16 (2008) 383–393 383 Zinc in Environmental Objects of Transbaikalia V. K. KASHIN Institute of General and Experimental Biology, Siberian Branch of the Russian Academy of Sciences, Ul. Sakhyanovoy 6, Ulan Ude 670047 (Russia) E-mail: [email protected] (Received January 24, 2008) Abstract The content of zinc in abiotic components (soil-forming rocks, natural waters, soils) and plants of forest-steppe, steppe, arid steppe and floodplain landscapes of Transbaikalia has been studied. A complex character of zinc distribution in environmental objects have been revealed: the content of zinc in soil- forming rocks and the soils of steppe and arid steppe landscapes approximately corresponds to the clarke, being for the rocks and soils of the forest-steppe landscapes equal to 0.4–0.7 of the clarke. It has been established that a deficient content of zinc (20–80 %) in the vegetation of steppe, meadow and agricultural landscapes is inherent in the most part of the territory under investigation. Key words: zinc, distribution, soil-forming rocks, natural waters, soils, plants, landscapes INTRODUCTION tabolism of proteins, carbohydrates, lipids and nucleic acids. Zinc represents a vitally important micro- The daily demand of an adult human for element for all the taxonomic groups of or- zinc amounts to 15–20 mg. The coefficient of ganisms on condition that its content is normal. its absorption from dietary intakes of vegeta- At the same time it is a hazardous toxicant ble and animal food mixture is as high as 33 %. when superfluously contained in an organism. The symptoms of this element deficiency for Zinc is involved in the structure of about human and animal organisms are exhibited via 300 enzymes those belong to all six classes list- growth inhibition and development delay, dis- ed in the catalogue of enzymes, and in the order of reproductive function, bone forma- structure of hormones (thymulin, prolactin, tion and hemogenesis, cutaneous diseases, de- somatin). This element supports the structure crease in immunity [4–6]. of more than 200 proteins, transcription acti- The deficiency of zinc in soils results in oc- vators those participate in the genetic infor- currence of various diseases of plants, decrease mation transfer [1, 2]. Due to this fact zinc can in their productivity and deterioration of qual- be considered to be a unique microelement: itative composition. At the same time a consid- none microelement forms such a number of erable part of the territories of Russia (75 %), bioinorganic compounds (bioclusters) and ex- the USA (43 States) and other countries are hibits so many various functions. The most im- characterized by the deficiency of zinc in soils portant enzymes containing zinc include car- [7, 8], which represents a serious problem for bonic anhydrase providing the hydration of ÑO 2 the health of population, livestock farming and in biological systems, and superoxide dismu- agriculture. This is especially urgent for the tase catalyzing the disproportionation of su- optimum development of children and teenag- – peroxide ion ( O2 ) and playing an important role ers as the most vulnerable part of population in the protection of cells from free radicals [3]. Zinc-containing fertilizers take a leading place Zinc-containing enzymes take part in the me- in the developed countries abroad among other 384 V. K. KASHIN fertilizers with microelements concerning the rocks, in some plant species as well as in phy- assortment and production volumes [8]. tomass harvested from 1 m2, upon 4- to 6-fold At the same time the increased concentra- repetition. The sampling was carried out dur- tion of zinc exert a toxic effect on living organ- ing the period of a higher biologic efficiency isms. So, the proficiency of zinc in a human or- of dominant plants. Water sampling from the ganism results in nausea, vomiting, respiratory water sources neighbouring to the key plots was embarrassment, pulmonary fibrosis [9]. Under carried out during low-water season (August– the conditions of an increased concentration of September). The destruction of the organic zinc in soils the population morbidity rate value matrix in samples was carried out using a dry with respect to cancer is observed to grow; in ashing technique at 480 îÑ. The content of zinc this connection zinc is referred to priority toxic was determined by atomic absorption spec- elements. However, the toxicity of zinc exhibits troscopy technique, analytical replicated trials be- a restricted distribution being connected mainly ing triple. The detection limit of zinc for soils and to a man-caused environmental contamination plants amounted to 0.5 and 0.1mg/kg, respective- due to corresponding manufactures. ly, for water it was equal to 1.0 mg/L. The relative Thus, the problem of zinc in biosphere is error of determination was about 8–10%. Math- characterized by two practically important as- ematical data processing was carried out using stan- pects biological one, connected with zinc defi- dard techniques described in [14]. ciency, and ecotoxicological one caused by the increased content of zinc. In this connection it is necessary to carry out monitoring of zinc con- RESULTS AND DISCUSSION tent in various parts of biogeochemical food Zinc in soil-forming rocks chain for different regions. The content of zinc is poorly known for the The content of zinc in soil-forming rocks landscapes of Transbaikalia. There are only sep- varied from 23 to 157mg/kg while the aver- arate data concerning zinc content in the some age variation level was equal to 41% (Table 1). soils and fodder plants of the southern areas of The lowest content of zinc (26–30mg/kg) was Buryatia [10, 11], as well as about the accumu- observed in alluvial and diluvium sandy depos- lation of this element by plants growing on ore its of the taiga landscapes, and the highest deposits [12]. The purpose of the present work one (100–140mg/kg) was noted for diluvium consisted in the studies on the features of zinc loamy deposits of the steppe landscapes. For distribution in soil-forming rocks, natural wa- the most part the content of zinc varies within ters, soils and plants of various Transbaikalian the range of 40–100mg/kg (75% of samples) landscapes constituting the major portion of with the average value for all the set of soil- water collecting area of the Baikal Lake basin. forming rocks under investigation amounting to 71mg/kg, which value is corresponding to EXPERIMENTAL the clarke of zinc in the lithosphere. From the geological staindpoint Transbaika- The studies were carried out over the 12 most lia represents rather non-uniform territory populated areas of Buryatia (Western Transbaika- where Pre-Cambrian, Palaeozoic, Mesozoic lia) located within the Selenga River basin that is and Cainozoic igneous, metamorphic, sedimen- the main tributary of the Baikal Lake. The key tary formations are developed. Granitoids pre- sampling sites, plots 100 ´ 100m in size were cho- vail among the rocks, and there are diorites, sen at the typical areas of the steppe, meadow syenites, gabbro, dunites, basalts, limestones, and agricultural landscapes according to the me- sandstones, clay slates, too [15]. The rocks of- thodical recommendations presented in [13]. Each ten replace spatially each other; this fact ex- plot was treated to obtain a basic soil section hibits a lithologic variety of the territory, and 4 to 6 semi-sections. At all the points a con- which is connected with the variability of the jugate sampling was carried out for the deter- lithogeochemical background. Zinc belongs to mination of zinc content in soil horizons and chalcophilous chemical elements accumulated in ZINC IN ENVIRONMENTAL OBJECTS OF TRANSBAIKALIA 385 TABLE 1 Content of zinc in soil-forming rocks of Transbaikalia Soil-forming rock n Content, mg/kg Cc Fluctuation rangeAverage Northern part of the territory under investigation Taiga landscapes Diluvium sandy deposits524–36290.4 Alluvial deposits523–31260.4 Sandy deposits834–45380.6 Forest-steppe landscapes Diluvium deposits, loams1640–60490.7 Diluvium deposits, sandy loams1032–47370.5 Alluvial deposits1627–45330.5 Southern part of the territory under investigation Arid steppe landscapes Diluvium deposits, loams1576–107931.4 Diluvium deposits, sandy loams1564–91791.2 Alluvial deposits1560–96771.1 Ancient lacustrine deposits683–97901.3 Aeolian sands759–71651.0 Steppe landscapes Diluvium deposits, loams590–1571201.8 Diluvium deposits, sandy loams2285–112991.5 Aeolian sands965–87761.1 Alluvial deposits1865–115861.3 Notes. 1. The Earth’s crust clarke amounts to 68 mg/kg [16]. 2. Cc is the clarke of concentration related to Earth’s crust clarke. the base rocks in increased amounts (84mg/kg). basalts of the Dzhida district the content of zinc In the intermediate and acid rocks its content in rocks ranges from 108 to 177mg/kg [17]. is to some extent lower, amounting to 73 and The content of zinc depends on grain-size 58mg/kg, respectively [16]. Zinc is present in composition of rocks, too. So, for sandy loams rocks mainly as zinc sulphide ZnS, as well it and sand this parameter is 1.5–1.9 times lower uses to substitute magnesium in silicates. as compared to that for loamy deposits. It is con- The analysis of spatial distribution of zinc nected with the fact that zinc, as well as many in soil-forming rocks has allowed one to reveal other dispersed chemical elements are concen- the following regional feature. For the rocks trated at the negatively charged surface of su- those compose the southern part of the territo- perfine clay particles due to the sorption via elec- ry under investigation (steppe and arid steppe trostatic interaction and even the incorporation landscapes) the content of zinc is on the aver- into interlamellar space, and formation of stron- age 2.3 times higher as compared to that for the ger inner-sphere complexes [18].