ACCUMULATION OF HEAVY METALS IN SOILS AND BOTTOM SEDIMENTS IN NORTHERN TAIGA RIVER BASINS IN THE AREAS WITH INTENSIVE FOREST CUTS

22 Apr 2021, 16:20
20m
oral Environmental Protection Systems Environmental Protection Systems

Speaker

S.D. Chubova

Description

The ecosystems of rivers basins of the Onega Peninsula are a representative model for studying the impact of forest management on the terrestrial and aquatic ecosystems of northern taiga. The upper and middle parts of the river basins are located in the middle of the peninsula, the lower - in the coastal parts. The seaside parts of the peninsula are included in the specially protected natural territory - the Onega Pomerania National Park (NP), and the middle part of the peninsula is in the zone of active forest management. Now logging has a high intensity, which creates risks of contamination of habitats for biodiversity of the NP. Migration of pollutants within river basins has not previously been studied for the Onega Peninsula, which is the extreme northern zone of taiga forest distribution. The purpose of this study was to assess the geochemical state of soils and bottom sediments of river, coastal and forest ecosystems of the river basins of the Onega Peninsula under forest cuts and in intact basins.
The content of heavy metals (HM) in soils and bottom sediments in the ecosystems of catchment basins of 10 small rivers of the Onega Peninsula, having different levels of anthropogenic load from logging, was investigated in 2020. Analysis for the content of HM carried out using an X-ray fluorescence method. HM content analysis was performed using X-ray fluorescence spectroscopy.
It was established that the lead content in soils and sediments increased in comparison to the intact river basin of the region is characteristic of bottom rivers sediments in the areas of felling of the current year and logging up to 10 years old.
An increase in heavy metals in the soils of forest ecosystems is noted in watersheds with active forest management areas. Excess of HM content in was found: zinc in 7 areas out of 9, lead - in 6 areas, cobalt and manganese - in 2, as well as excess MPC in nickel are observed in all samples. For the studied soils, excess background values of TM content in soils of the Arkhangelsk region for zinc are 50% of samples, 89% for lead. Significant excesses of other heavy metals were not noted. Based on the information obtained, the total soil contamination index (Zc) was calculated. In general, at present, the soils of the Onega Peninsula can be classified as low contaminated by the indicator of total contamination with heavy metals (Zc) The lowest value of Zc = 6.13 is characteristic of the soils of the catchment area river Lopshengi, which does not have areas of logging, and the highest Zc = 12.32 for soil samples, in the basins of the rivers area of Lake Summer Zolotitsy, which have a high intensity and cutting of 2010 - 2020 year.
It is established, that both the sediments of the studied rivers and the forest soils of the basins of these rivers near the areas of active forest management accumulate lead, the content of which is not reduced during the initial periods of reforestation (up to 10 years). Soils also accumulate zinc, which is not observed in bottom sediments. At the same time, pollution with other studied heavy metals is not noted. Their level in soils and sediments lower than normative level, but it generally higher than in control area that does not have them. The revealed excess of normative and background indicators of the HM content in soils and bottom sediments in areas of intensive recent logging may be associated with the use of logging equipment and vehicles, as well as violation of the structure of soils and slow restoration of ground vegetation.
In addition to the revealed accumulation of lead and zinc, bottom deposits and soils of the Onega Peninsula have a generally low level of contamination with HM. This indicates that the disruption of the natural balance of heavy metals is in its initial stages, but due to the toxicity of pollutants and their risk of rare species of animals and plants of NP, urgent measures are needed to prevent lead and zinc from entering the food chains of the ecosystem.

Publication IOP Conference Series: Earth and Environmental Science
Affiliation of speaker ITMO Univerrsity

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