Geochemical investigations of potentially toxic trace elements in urban sediments of Idrija

Špela Bavec

doi:10.5474/geologija.2015.009

Abstract

Urban areas and associated human activities (industry, traffic, processes of mining and ore extracting, etc.) have induced anthropogenic emissions of potentially toxic trace elements (PTTE), which can present risk to living organisms and ecosystems in case of enriched levels. An example of such area in Slovenia is the Idrija town, the central part of the second largest Hg mining district in the world, which is heavily contaminated with Hg in all environmental compartments. The knowledge about levels and distribution of other PTTE in Idrija is very limited due to the outstanding Hg related problems. In this study the geochemical investigation of PTTE (As, Cd, Co, Cr, Cu, Mo, Ni, Pb and Zn) was performed in urban stream and road sediments of Idrija town for the first time. In addition, solid phases of PTTE were observed using SEM/EDS and their potential sources were assessed. The results show that the levels of PTTE in urban stream and road sediments are mostly below international guidelines, except for Cu some high values were measured in road sediments. The highest Cu level was determined in the vicinity of a commutator production industry. The associations of Cu with other elements in solid phases are very diverse, which is why the analyses could not reveal the specific source of high Cu levels.

Highlights

Trace elements are chemical elements that occur in natural and perturbed systems in small amounts and among others include arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), and zinc (Zn) (Adriano, 1986) that were investigated in this study
The basic statistics of potentially toxic trace elements (PTTE) levels in the road sediment samples and stream sediment samples are presented in Table 1 and Fig. 3
Median values were selected for comparison, because strong positive skewness, kurtosis (Table 1) and histogram inspection showed that the bulk of values for all elements were clustered around the median on the left side of the histogram

Summary

Introduction

Trace elements are chemical elements that occur in natural and perturbed systems in small amounts and among others include arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb), and zinc (Zn) (Adriano, 1986) that were investigated in this study. An inadequate supply of trace elements can affect the living organism in two ways: either there is a lack of a trace element in the living organism (deficiency) or an excess of a trace element in the living organism (toxicity). In both cases, the growth of a plant or an animal is abnormal, so it can neither grow nor complete some metabolic cycle (Adriano, 1986; Kabata Pendias & Pendias, 2001). Anthropogenic influences induced PTTE emissions that often accumulate in earth materials of urban areas (urban materials) (Thornton et al, 2008; Johnson et al, 2011)

Methods

Results

Conclusion