New geochemical data for defining origin and distribution of mercury in groundwater of a coastal area in southern Tuscany (Italy)

A geochemical study was conducted in a coastal plain in the Orbetello Lagoon area in southern Tuscany (Italy), acquiring new data on groundwater, lagoon water, and stream sediment for insights into the origin, distribution, and behaviour of mercury in a Hg-enriched carbonate aquifer. The main hydrochemical features of the groundwater are ruled by the mixing of Ca-SO4 and Ca-Cl continental fresh waters of the carbonate aquifer and Na-Cl saline waters of the Tyrrhenian Sea and Lagoon of Orbetello. Groundwater had highly variable Hg concentrations (< 0.1-11 μg/L) that were not correlated with the percentage of saline water, depth in the aquifer, or distance from the lagoon. This excluded the possibility that saline water could be the direct source of Hg in groundwater and responsible for release of the element through interaction with the carbonate lithologies of the aquifer. The origin of Hg in groundwater could be ascribed to the Quaternary continental sediments overlying the carbonate aquifer because i) high Hg concentrations were found in the continental sediments of the coastal plain and in the contiguous lagoon sediments; ii) waters from the upper part of aquifer had the highest Hg concentrations; iii) Hg levels in groundwater increased with increasing thickness of the continental deposits. The high Hg content in the continental and lagoon sediments is geogenic due to regional and local Hg anomalies and to sedimentary and pedogenetic processes. It can be assumed that i) water circulating in these sediments dissolves the solid Hg-bearing constituents and mobilises this element mainly as chloride complexes; ii) Hg-enriched water moves from the upper part of the carbonate aquifer due to the cone of depression generated by intense pumping of groundwater by fish farms in the study area

Exploring distribution of potentially toxic elements in soil profiles to assess the geochemical background and contamination extent in soils of a metallurgical and industrial area in Kosovo

This geochemical study explored the distribution of potentially toxic elements (PTEs), such as As, Cd, Co, Cr, Cu, Ni, Pb, Sb, Tl, U, and Zn, along soil profiles of a metallurgical and industrial area in Kosovo, with the aim of assessing geochemical background and contamination threshold of PTEs in soil, and defining surface and vertical level and extent of soil contamination by PTEs. The geochemical background was assessed by exploratory data analysis of PTE concentrations in soil profiles. The upper limit of geochemical background (contamination threshold) was used as reference value to calculate the single pollution index and establish the PTE contamination level. Cadmium, Pb, Sb, Zn were the primary soil contaminants and As, Cu, Tl the secondary ones. The main sources of soil contaminants were the Zvecan smelter for Pb, Sb, As, Cu, Tl, and the Trepca industrial complex for Cd and Zn. The highest levels of Pb and Sb contamination were found up to depths between 30 and 60 cm in soil profiles within 5 km north and south-east of the Zvecan smelter. Contamination by Pb and Sb decreased with depth and affected the whole thickness of soil profiles closer the smelter. Cadmium and Zn contamination declined with distance from the Trepca industrial complex and decreased with depth, extending down to depths of 40–90 cm and 30–70 cm, respectively. Anomalous natural concentrations of Co, Cr, and Ni were found in soils collected in the northern part of the study area, where the geology consists mainly of ultrabasic and basic magmatic rocks

Fractionation and geochemical mobility of heavy elements in soils of a mining area in northern Kosovo

This paper reports the results of a geochemical study focusing on the partitioning of As, Cd, Cu, Pb, Sb and Zn in soils of the Kosovska Mitrovica mining area in northern Kosovo. The main objective was to define the element mobility in soil and potential bioavailability in relation to soil contamination levels. The Kosovska Mitrovica area is one of the main industrial sites in the former Yugoslavia and a world-class mining district in Europe. Extensive and locally very marked contamination mainly by Pb, Zn, Cd and Sb was found in soils, with the highest concentrations measured close to the Zvecan smelter. The study of As, Cd, Cu, Pb, Sb and Zn partitioning in the water soluble, extractable with 0.11 M acetic acid, reducible, oxidable and residual fractions of soils revealed that Pb was mainly associated with the reducible fraction, Cd with the extractable and reducible fractions, and As, Cu, Sb and Zn with the residual fraction. Heavy element fractionation in contaminated soils was influenced by the presence of owner mineralogical phases related to the emissions of the Zvecan smelter and to materials windborne from mining and industrial dumps, as well as originated by in situ processes. The order of mobility of these heavy elements in contaminated soils resulted as follows: Cd ≫ Zn ≫ Pb ≫ Sb > As > Cu. Anthropogenic amounts of heavy elements were distributed in all soil fractions, with the most relevant enrichments in the extractable and reducible ones. Anthropogenic inputs were responsible for some deviations from natural fractionation, mainly for Pb, Zn and Cd. A significant amount of Cd, Pb and Zn in contaminated soils was rather mobile, which suggests that these elements can be readily available to plants and soil organisms

Caratterizzazione geochimica dei suoli dell'area urbana di Siena ed utilizzo dei lombrichi come bioindicatori

Nelle aree urbane il traffico veicolare rappresenta una delle principali fonti di contaminazione dell’ambiente di superficie, la cui chimica, in seguito alla variazione qualitativa e quantitativa dei contaminanti immessi, è soggetta ad una continua trasformazione. Nell’area di Siena è in fase di realizzazione una ricerca geochimica finalizzata alla valutazione dell’impatto del traffico veicolare sull’ambiente di superficie attraverso la determinazione dei contenuti di elementi in traccia in differenti comparti di esposizione: aria, suolo, organismi vegetali ed animali. Siena è una città di dimensioni medio-piccole, dove le attività industriali sono limitate; pertanto nell’area urbana la principale fonte di contaminanti è rappresentata dal traffico veicolare a cui, in inverno, si aggiunge l’apporto fornito dal riscaldamento domestico. In questo lavoro sono riportati i risultati preliminari inerenti le concentrazioni di elementi in traccia di interesse ambientale (per es., piombo, antimonio, cadmio, nichel, rame e zinco) in suoli ed esemplari di lombrico della specie Nicodrilus caliginosus (Savigny), campionati in siti urbani, peri-urbani ed extra-urbani di Siena. Nell’ambito della ricerca sono stati determinati i contenuti totali degli elementi: Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Pd, Pt, Rh, Sb, U e Zn, nonché la loro ripartizione nelle principali frazioni del suolo (estraibile, riducibile, ossidabile e residuale) allo scopo di definire la mobilità delle specie chimiche di interesse e stabilire le relazioni che intercorrono con l’assorbimento da parte dei lombrichi. Come bioindicatori della qualità del suolo sono stati utilizzati i lombrichi (Anellidi appartenenti alla famiglia Lumbricidae) poiché in grado di assorbire ed accumulare gli elementi chimici sia attraverso l’assorbimento dermale sia mediante l’ingestione delle particelle di suolo. I dati analitici prodotti hanno indicato che piombo ed antimonio sono gli elementi chimici maggiormente influenzati dalla circolazione veicolare, con le più elevate concentrazioni medie registrate nei suoli urbani (Pb=112.5 mg/kg; Sb=5.6 mg/kg). Per cadmio, manganese, rame e zinco è stato riscontrato nei suoli dei siti interessati dal traffico su strada un minore incremento delle concentrazioni rispetto al background geochimico locale. Per gli altri elementi chimici analizzati (cobalto, cromo, ferro, nichel, uranio e platinoidi) non è stata rilevata nessuna variazione significativa della loro abbondanza nei suoli dell’area di studio. Negli esemplari di lombrico le concentrazioni degli elementi chimici analizzati delineano un modello di distribuzione analogo a quello descritto per i contenuti totali nel suolo. Zinco e cadmio sono risultati gli unici elementi bioconcentrati, con contenuti nel lombrico che superano di un ordine di grandezza quelli del suolo

Uptake and bioaccumulation of heavy elements by two earthworm species from a smelter contaminated area in northern Kosovo

As, Cd, Cu, Pb, Sb and Zn concentrations were determined in two earthworm species (Allolobophora rosea and Nicodrilus caliginosus) from a mining and industrial area in northern Kosovo and compared with their contents in the bulk soil and the main soil fractions. Earthworm specimens were collected at fifteen sites located at different distances from a Pb–Zn smelter along a gradient of decreasing contamination. Individuals of A. rosea and N. caliginosus showed similar tissue levels of As, Cd, Cu, Pb, Sb and Zn, suggesting that earthworm species belonging to the same eco-physiological group have a similar propensity to uptake and bioaccumulate heavy elements. Cd, Pb, Sb and Zn concentrations in both earthworm species were positively correlated with the respective total soil contents and generally decreased with distance from the smelter. The bioaccumulation factor (BAF) revealed that Cd and Zn were the only elements bioaccumulated by earthworms. The rank order of BAF values for both species was as follows: Cd > > Zn > > Cu > As = Pb = Sb. The absorption of Cd, Pb, Sb and Zn by earthworms mostly depended on the extractable, reducible and oxidable soil fractions, suggesting that the intestine is likely the most important uptake route. The extractable soil fraction constantly influenced the uptake of these heavy elements, whereas the reducible fraction was important mainly for Pb and Zn. The water soluble fraction had an important role especially for the most mobile heavy elements such as Cd and Zn, suggesting that dermal uptake is not negligible. As a whole, the analytical data indicate that soil fractionation patterns influence the uptake of heavy elements by earthworms, and the extractable fraction is a good predictor of heavy element bioavailability to these invertebrates in soil

Influence of ore processing activity on Hg, As and Sb contamination and fractionation in soils in a former mining site of Monte Amiata ore district (Italy)

A geochemical study was carried out at the former Abbadia San Salvatore (ASS) mining site of the Monte Amiata ore district (Italy). Hg, As and Sb total contents and fractionation using a sequential extraction procedure were determined in soil and mining waste samples. Ore processing activities provided a different contribution to Hg contamination and concentration in soil fractions, influencing its behaviour as volatility and availability. Soils of roasting zone showed the highest Hg contamination levels mainly due to the deposition of Hg released as Hg0 by furnaces during cinnabar roasting. High Hg contents were also measured in waste from the lower part of mining dump due to the presence of cinnabar. The fractionation pattern suggested that Hg was largely as volatile species in both uncontaminated and contaminated soils and mining waste, and concentrations of these Hg species increased as contamination increased. These findings were in agreement with the fact that the ASS mining site is characterized by high Hg concentrations in the air and the presence of Hg0 liquid droplets in soil. Volatile Hg species were also prevalent in uncontaminated soils likely because the Monte Amiata region is an area characterized by anomalous fluxes of gaseous Hg from natural and anthropogenic inputs. At the ASS mining site soils were also contaminated by Sb, while As contents were comparable with its local background in soil. In all soil and waste samples Sb and As were preferentially in residual fraction

Chemical and biological methods to evaluate the availability of heavy metals in soils of the Siena urban area (Italy)

A biogeochemistry field study was conducted in the Siena urban area (Italy) with the main objective of establishing the relationship between available amounts of heavy metals in soil assessed by a chemical method (soil fractionation) and bioavailability assessed by a biological method (bioaccumulation in earthworm tissues). The total content of traffic-related (Cd, Cu, Pb, Sb, Zn) and geogenic (Co, Cr, Ni, U) heavy metals in uncontaminated and contaminated soils and their concentrations in soil fractions and earthworms were used for this purpose. The bioavailability of heavy metals assessed by earthworms did not always match the availability defined by soil fractionation. Earthworms were a good indicator to assess the bioavailability of Pb and Sb in soil, while due to physiological mechanisms of regulation and excretion, Cd, Cu and Zn tissue levels in these invertebrates gave misleading estimates of their bioavailable pool. No relationship was identified between chemical and biological availability for the geogenic heavy metals, characterized by a narrow range of total contents in soil. The study highlighted that chemical and biological methods should be combined to provide more complete information about heavy element bioavailability in soils

Frazionamento di elementi in traccia nei suoli dell'area urbana di Siena e loro assorbimento da parte dei lombrichi

Le aree urbane rappresentano ambienti a rischio di contaminazione da specie chimiche organiche ed inorganiche in quanto soggette alla pressione di diverse attività antropiche, tra cui il traico veicolare. Nell’area di Siena è stato condotto uno studio volto a valutare l’impatto del traffico veicolare sulla presenza e distribuzione areale di alcuni elementi in traccia nel suolo di zone urbane, peri-urbane ed extra-urbane, ed il loro trasferimento ai lombrichi della specie Nicodrilus caliginosus. I lombrichi sono organismi sensibili alla presenza di elementi in traccia nel suolo e per questo efficacemente utilizzati negli studi dei livelli di contaminazione. Nei campioni di suolo e negli esemplari di lombrico sono stati misurati i contenuti di Cd, Co, Cr, Cu, Ni, Pb, Sb, U e Zn, ed è stata definita la loro ripartizione nelle principali frazioni del suolo: solubile, estraibile, riducibile, ossidabile e residuale. Pb e Sb sono risultati gli elementi il cui contenuto nel suolo è maggiormente inluenzato dal traffico veicolare, seguono Zn, Cd e Cu. Per tutti questi elementi le concentrazioni più elevate contraddistinguono i suoli urbani s.s. Gli elementi considerati mostrano tre diversi pattern di ripartizione nelle frazioni del suolo: Co, Cr, Cu, Ni, Sb, U e Zn sono presenti prevalentemente nella frazione residuale, Pb nelle frazioni riducibile e residuale, Cd principalmente in quella estraibile. Per Cd, Cu, Pb, Sb e Zn l’apporto del traffico veicolare si distribuisce a vario grado in tutte le frazioni non residuali. Negli esemplari di lombrico le concentrazioni degli elementi in traccia rivelano un modello di distribuzione analogo a quello descritto per i loro contenuti totali nel suolo. Le modalità ed il grado di assorbimento degli elementi in traccia da parte dei lombrichi appaiono influenzate dal tipo di ripartizione nel suolo. Nel complesso la frazione estraibile è quella che maggiormente determina le concentrazioni di Cd, Pb, Sb e Zn nei lombrichi, mentre un contributo minoritario è dovuto anche alle frazioni solubile ed ossidabile; la frazione ossidabile è quella che regola in maggior misura i contenuti di Cu nei lombrichi

Potentially toxic element contamination in soil and accumulation in maize plants in a smelter area in Kosovo

A biogeochemical field study was carried out in the industrial area of Kosovska Mitrovica in northern Kosovo, where agricultural soils were contaminated by potentially toxic elements due to smelting activity. Total and bioavailable contents of As, Cd, Co, Cu, Pb, Sb, U and Zn in soil and their concentrations in maize roots and grains were determined. Soil contamination by As, Cd, Cu, Pb, Sb and Zn was variable from slightly to highly contaminated soils and influenced both the bioavailable fraction and accumulation of these potentially toxic elements in maize tissues. The comparison between potentially toxic element concentrations in roots and grains indicated that maize is able to limit the transfer of non-essential elements to edible parts. The plant-to-soil bioconcentration indices suggested that the transfer of potentially toxic elements from soil to plant was predicted better by bioavailable concentrations than by the total contents. These indices further identified some competitions and interactions among these elements in root uptake and root-to-grain translocation