Assessment of the metal pollution in surface sediments of coastal Tasaul Lake (Romania)

Dan Vasiliu,Andra Bucse,Catalin Gheablau,Ion Stanescu,Naliana Lupascu,Bogdan Ispas

doi:10.1007/s10661-020-08698-0

Abstract

Forty-three surface sediment samples were collected in September 2019 from Tasaul Lake (Black Sea coast, Romania) to examine the metal distribution patterns, assess the level of metal contamination, and identify the pollutant sources. The determined mean metal concentrations were as follows: Al 49,772 mg/kg, Zn 84.40 mg/kg, Cr 83.70 mg/kg, V 76.45 mg/kg, Ni 42.53 mg/kg, Cu 34.27 mg/kg, Pb 26.30 mg/kg, As 12.49 mg/kg, and Hg 0.06 mg/kg. The metals in the surface sediments of Tasaul Lake displayed moderate spatial variation, with higher metal concentrations mainly occurring in the south and southeast (As, Pb, and Hg), southwest (Cu and Zn), and west of the lake (Cr, Ni, and V). Heavy metal contamination in sediments is assessed using pollution indices such as enrichment factor, contamination factor, and pollution load index. The highest CFs and EFs were determined for As (moderate to high pollution), followed by Pb (low to moderate pollution). The Cu, Zn, and Hg pollution indices showed values corresponding to low pollution levels, while Ni, Cr, and V presented the lowest indices, suggesting unpolluted sediments. Multivariate statistical analyses were performed to identify the origin of the analyzed heavy metals. Cr was predominantly sourced from lithogenic components, Ni and V originated from both natural and anthropogenic sources, and As, Cu, Zn, Pb, and Hg showed mainly anthropogenic sources such as agricultural runoff, domestic and industrial wastewater discharges, and quarrying activities.

Highlights

Coastal lakes are threatened ecosystems due to the numerous human activities carried out within their watersheds, resulting in multiple pressures that negatively impact ecosystem components and human health
Heavy metal pollution is one of the major pressures impacting lacustrine ecosystems owing to the toxicity, abundance, and persistence of heavy metals in the environment and their subsequent accumulation in the environment and organisms (Rippey et al 2008; Atici et al 2008; Varol 2011)
The study area is covered by clayey silt (40% of samples), mostly in the western part, and sandy silt (56% of samples), except for two sampling stations located in the vicinity of Ada Island (TS29 and TS30), where the coarse fraction represents > 80% (Fig. 2)

Summary

Introduction

Coastal lakes are threatened ecosystems due to the numerous human activities carried out within their watersheds, resulting in multiple pressures (eutrophication, pollution, overfishing, etc.) that negatively impact ecosystem components and human health. Metals enter lakes from different sources, such as rock weathering, wind-borne soil particles, disposal of liquid effluents, terrestrial runoff carrying numerous chemicals resulting from urban, industrial, and agricultural activities, and atmospheric deposition (Jiang et al 2012) and are. Lake sediments act as either a permanent or temporary sink of metals; their level of contamination provides an overall picture of health status of the lake ecosystem. There are many coastal lakes along the Romanian Black Sea littoral region, some of them (those located in the south) strongly impacted by human activities (tourism, agriculture, industry, urban extension, etc.). Its importance at regional scale results from the ecosystem services offered, provisioning (fishery and water for agriculture purposes) and cultural (recreational and aesthetics)

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Conclusion