Heavy Metals in Sapropel of Lakes in Suburban Territories of Vilnius (Lithuania): Reflections of Paleoenvironmental Conditions and Anthropogenic Influence

Gytautas Ignatavičius,Howlader Rahidul Hassan,Jonas Satkūnas,Alma Grigienė,Vaidotas Valskys,Irena Nedveckytė

doi:10.3390/min12010017

Gytautas Ignatavičius, Howlader Rahidul Hassan + Show 4 more

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https://doi.org/10.3390/min12010017

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Abstract

Geochemical and lithological parameters of sapropel in lakes, combined with pollen data and radiocarbon 14C dating, contain a wide spectrum of environmental information. This includes records of fluctuations of water level and changes of conditions of sedimentation, accumulation of organic matter and chemical elements due to climate change, human impacts and other environmental changes. Rising concentrations of hazardous substances in the natural sediments are likely to be a high risk to the natural environment. At the same time, they can greatly reduce opportunities for environmental engineering of lakes. Four lakes with different trophic states and anthropogenic pressures were chosen for this study in Lithuania. Higher concentrations of elements like Cr, Cu and Zn were not only detected in the top most layers of sapropel but also in deeper layers and are attributed to lithogenic association of trace elements in such deep layers. Concentrations of Pb were detected only in upper layers of sapropel which indicates the impact of anthropogenic activity. The main source of heavy metals was multidimensional anthropogenic pollution leading to a biogenic–anthropogenic association of elements. Sapropel with low concentrations of heavy metals exhibits a different inter-association matrix because most of the elements tend to form lithogenic–clastogenic associations.

Highlights

Lakes continuously accumulate sediments after the formation of their basins and the time for development can last for several thousand years or even longer, dependent on paleoenvironmental conditions
Interrelations of heavy metals and associations with organic and mineral matter can depend on vegetation, anthropogenic load, depth and bottom relief of lakes as well as the nature of geological layers and geomorphology of the catchment area of the lake
It is noteworthy that variations of concentrations of heavy metals are influenced by anthropogenic activity, and geochemical processes

Summary

Introduction

Lakes continuously accumulate sediments after the formation of their basins and the time for development can last for several thousand years or even longer, dependent on paleoenvironmental conditions. The study area occurs in the zone of glacial formations of the Last (Late Weichselian) glaciation and the lacustrine sedimentation history is mainly. Sapropels are types of fine organogenic sediments commonly found in lakes in the North Temperate Zone [1,2,3]. According to the classification of lacustrine sediments used in Lithuania [4], the sapropel is water laid very fine material containing more than 15% of organic matter and, depending on the amount of admixture, can be organic, carbonatic, sandy, silty or clayey. The intensity and combination of these processes are very variable depending on the different geological and geomorphological settings, hydrological regimes and atmospheric conditions, as well as human activities [5,6,7]

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