The occurrence of heavy metals in irrigated and non-irrigated arable soils, NW Albania

The Presence of Ultra-Traces of Persistent Organic Pollutants (POPs) and Heavy Metals in Some Areas of Molise: The Importance of a "Blank" in Public Health Studies

The emission of chemicals into the environment has increased in a not negligible way as a result of the phenomenon of globalization and industrialization, potentially also affecting areas always considered as "uncontaminated". In this paper, five "uncontaminated" areas were analyzed in terms of the presence of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs), comparing them with an "environmental blank". Chemical analyses were carried out using standardized protocols. The 'environmental blank' results revealed the presence of Cu (<64.9 μg g^-1), Ni (<37.2 μg g^-1), and Zn (<52.6 μg g^-1) as HMs and fluorene (<17.0 ng g^-1) and phenanthrene (<11.5 ng g^-1) as PAHs. However, regarding the results of the pollution status of the areas under study, fluorene (#S1, 0.34 ng g^-1; #S2, 4.3 ng g^-1; #S3, 5.1 ng g^-1; #S4, 3.4 ng g^-1; #S5, 0.7 ng g^-1) and phenanthrene (#S1, 0. 24 ng g^-1; #S2, 3.1 ng g^-1; #S3, 3.2 ng g^-1; #S4, 3.3 ng g^-1; #S5, 0.5 ng g^-1) were found in all areas, while the other PAHs investigated were detected at a concentration averaging less than 3.3 ng g^-1. HMs were found in all of the investigated areas. In particular, Cd was detected in all areas with an average concentration of less than 0.036 μg g^-1, while Pb was absent in area #S5, but present in the other areas with an average concentration of less than 0.018 μg g^-1.

Influence of soil inorganic amendments on heavy metal accumulation by leafy vegetables

The present study aims to assess the effect of four inorganic soil amendments, such as lime (CaCO3), red mud consisting of 75% hematite (Fe2O3), gypsum (CaSO4·2H2O), and Al oxide (Al2O3), of an alkaline heavy metal-contaminated soil. For this purpose, a pot experiment was conducted by physically mixing individual six subsamples of a soil sample collected from Thessaly area with four inorganic soil amendments along with two leafy plants, spinach and lettuce. Al oxide causes the maximum reduction of the water-soluble Cu concentration, as its concentrations is no longer detectable. The Cu availability index decreases when aluminum oxide was used. The use of gypsum and red mud caused almost equal reduction while the smallest decrease was caused by the use of lime. The Zn availability index decreased equally when aluminum oxide and gypsum were mixed with the soil sample. The highest reduction of Cu and Zn transfer coefficient (TC) was observed when the Al2O3 was used. In spinach, Zn TC reduction was 39.8% and Cu TC reduction was 41.0%. In lettuce, the addition of Al2O3 led to Cu TC reduction of over 37.3% and Zn TC reduction of up to 38.7%. Generally, Al2O3 nanoparticles may function as suitable sorbents for the removal of Zn and Cu from soil samples, with an increasing effectiveness in spinach rather than lettuce. Liming materials seem to increase the soil alkalinity and promote the complexation of soluble heavy metals with hydroxide ions leading to immobilization of heavy metals in soil and reduce their amount in leafy vegetables. Remediation of contaminated soils is considered necessary to reduce environmental risks and to achieve the means available to increase agricultural production of safe and quality food.

Background concentrations and spatial distribution of heavy metals in Albania's soils

This research aimed to determine the background and precautionary values of Cd, Cr, Cu, Ni, Pb, Zn, Co, As, and Hg and provide the spatial distribution of these metals in Albania's soils using statistical and geostatistical methods. Since the distribution of the data was commonly not Gaussian, they were transformed into their natural logarithm for deriving background concentrations and precautionary values. Background concentrations were defined as antilog of the median. Precautionary concentration values for soil protection were defined as antilog of 90th percentile of the ln-transformed data. Background concentrations in forest soils were larger compared to those in soils under other land use types. The largest background concentrations for Cd, Cr, Ni, Cu, Co, and Zn were found in forest soils formed on magmatic rocks, while largest concentrations of Pb and Hg were found in soils formed on flysch and molasse. The background values and precautionary concentration values (in brackets) (mg kg^-1) for agricultural soils across flysch/molasses and quaternary deposits were as follows: Cd 0.24 (0.82), Cr 131.63 (527.42), Cu 41.26 (72.75), Ni 287.15 (632.70), Pb 19.11 (284.86), Zn 81.80 (113.90). The largest background values for Cd and Zn were found in Phaeozems, for Cr, Pb, and Co in Luvisols and Cambisols, and for Cu, Hg, and Ni in Fluvisols. The proposed background concentrations and precautionary values complete the picture of metal contents in European soils, can be used as reference concentrations for the Albanian environmental legislation, and allow the identification of potential contamination hot spots.

Level of Contamination Assessment of Potentially Toxic Elements in the Urban Soils of Volos City (Central Greece)

A three-year study, designed to record the level of potentially toxic elements within the urban complex in the city of Volos, Greece, was carried out between 2018 and 2020. For the needs of the aforementioned study, 62 surface (0–15 cm) soil samples were collected each year (i.e., 186 samples in total) from an urban area of 3.65 km2, and the average value of pseudo-total metal concentration was measured. Soil pollution indices, such as the contamination factor (CF) and the geo-accumulation index (Igeo), were estimated regarding each of the metals of interest. The respective thematic maps were constructed, and the spatial variability of the contamination degree was displayed. Higher values of the CF and Igeo were obtained near the heavy traffic roads and beside the railway station, the bus stations, and the commercial port. The maps based on the pollution indices, along with the database that was constructed using the appropriate mathematical tools of geostatistical analysis, may be a useful tool for monitoring, prediction, and continuous verification of contamination in the urban soils of Volos city.

Potentially toxic elements in saltmarsh sediments and common reed (Phragmites australis) of Burullus coastal lagoon at North Nile Delta, Egypt: A survey and risk assessment

Burullus lagoon is the second largest lake in Egypt. However, there has never been a comprehensive survey which studied nineteen potentially toxic elements in sediments and plants and evaluated the associated potential risk. Thus, we aimed to study the total and potentially available content of As, Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Sb, Se, Sn, Tl, V, and Zn in the sediments and common reed (Phragmites australis) at thirty two sites along the entire lagoon and connected drains. Contamination Factor (CF), Pollution Load Index (PLI), Geo-accumulation Index (I_geo), and Enrichment Factor (EF) were calculated to assess the grade of contamination. Element accumulation factor (AF) and bio-concentration ratio (BCR) were also calculated. Aluminum showed the highest median (mg kg^-1) total content (41,200), followed by Fe (30,300), Mn (704.7), V (82.0), Zn (75.5), Cr (51.2), Cu (47.8), Ni (44.3), As (31.9), Tl (24.6), Co (21.4), Se (20.3), Sb (17.6), Sn (15.6), Mo (11.3), and Hg (16.6 μg kg^-1). Values of the EF, CF, and I_geo showed that the sediments were heavily contaminated with As, Sb, Se, Tl, Mo, Sn, Co, Ni, and Cu. The drained sediment had significantly higher values of total and potentially available element content than the lagoon sediments. Sediments of the middle and western area showed significantly higher contents of total and available elements than the eastern section. The BCR and AF values indicate that the studied plant is efficient in taking up high amounts of Zn, Fe, As, Sn, Tl, Ni, Mo, Mn; then Co, Cu, and V. The results exhibit a dramatic contamination at certain sites of the lagoon, and the studied PTEs have a predominant role in contamination-related ecological risk. Further investigations concerning redox-induced mobilization of PTEs in sediments, the risk of fish contamination and the potential health hazards are highly recommended.

Bioavailability and health risk assessment of potentially toxic elements in Thriasio Plain, near Athens, Greece

Elevated concentrations of potentially toxic elements (PTEs) are usually found in areas of intense industrial activity. Thriasio Plain is a plain near Athens, Greece, where most of the heavy industry of the country has been situated for decades, but it also is a residential and horticultural area. We aimed at measuring the levels of PTEs in soils and indigenous plant species and assessing the health risk associated with direct soil ingestion. Samples of soils at roadsides and growing plants were collected from 31 sites of that area. Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn were measured in both soils (as pseudo-total) and aerial plant tissues. We found that As, Cd, Cr, Cu, Ni, Pb and Zn were higher than maximum regulatory limits. Element concentrations in plants were rather lower than expected, probably because indigenous plants have developed excluder behaviour over time. Copper and Zn soil-to-plant coefficients were highest among the other elements; for Cu this was unexpected, and probably associated with recent Cu-releasing industrial activity. Risk assessment analysis indicated that As was the element contributing more than 50 % of the health risk related to direct soil ingestion, followed by Cr, Pb, and, surprisingly, Mn. We concluded that in a multi-element contamination situation, elevated risk of PTEs (such as As, Cr and Pb) may reduce the tolerance limits of exposure to less-toxic elements (here, Mn).

Bioavailability and risk assessment of potentially toxic elements in garden edible vegetables and soils around a highly contaminated former mining area in Germany

Although soil contamination by potentially toxic elements (PTEs) in Europe has a history of many centuries, related problems are often considered as having been dealt with due to the enforcement of tight legislations. However, there are many unsolved issues. We aimed to assess PTE levels in highly contaminated soils and in garden edible vegetables using human health risk indices in order to evaluate the availability and mobilization of arsenic (As), copper (Cu), manganese (Mn), mercury (Hg), lead (Pb), and zinc (Zn). In four gardens in Germany, situated on, or in the vicinity of, a mine dump area, we planted beans (Phaseolus vulgaris ssp. nanus), carrots (Daucus sativus) and lettuce (Lactuca sativa ssp. capitata). We examined soil-to-plant mobilization of elements using transfer coefficient (TC), as well as soil contamination using contamination factor (CF), enrichment factor (EF), and bioaccumulation index (I_geo). In addition, we tested two human health risk assessment indices: Soil-induced hazard quotient (HQ_S) (representing the "direct soil ingestion" pathway), and vegetable-induced hazard quotient (HQ_V) (representing the "vegetable intake" pathway). The studied elements were highly elevated in the soils. The values in garden 2 were especially high (e.g., Pb: 13789.0 and Hg: 36.8 mg kg^-1) and largely exceeded the reported regulation limits of 50 (for As), 40 (Cu), 400 (Pb), 150 (Zn), and 5 (Hg) mg kg^-1. Similarly, element concentrations were very high in the grown vegetables. The indices of CF, EF and I_geo were enhanced even to levels that are rarely reported in the literature. Specifically, garden 2 indicated severe contamination due to multi-element deposition. The contribution of each PTE to the total of measured HQ_S revealed that Pb was the single most important element causing health risk (contributing up to 77% to total HQ_S). Lead also posed the highest risk concerning vegetable consumption, contributing up to 77% to total HQ_V. The presence of lead in both cases was followed by that of As, Mn and Hg. We conclude that in multi-element contamination cases, along with high-toxicity elements (here, Pb, As and Hg) other elements may also be responsible for increasing human health risks (i.e., Mn), due to the possibility of adverse synergism of the PTEs.

Identification and apportionment of hazardous elements in the sediments in the Yangtze River estuary

In this study, positive matrix factorization (PMF) and principal components analysis (PCA) were combined to identify and apportion pollution-based sources of hazardous elements in the surface sediments in the Yangtze River estuary (YRE). Source identification analysis indicated that PC1, including Al, Fe, Mn, Cr, Ni, As, Cu, and Zn, can be defined as a sewage component; PC2, including Pb and Sb, can be considered as an atmospheric deposition component; and PC3, containing Cd and Hg, can be considered as an agricultural nonpoint component. To better identify the sources and quantitatively apportion the concentrations to their sources, eight sources were identified with PMF: agricultural/industrial sewage mixed (18.6 %), mining wastewater (15.9 %), agricultural fertilizer (14.5 %), atmospheric deposition (12.8 %), agricultural nonpoint (10.6 %), industrial wastewater (9.8 %), marine activity (9.0 %), and nickel plating industry (8.8 %). Overall, the hazardous element content seems to be more connected to anthropogenic activity instead of natural sources. The PCA results laid the foundation for the PMF analysis by providing a general classification of sources. PMF resolves more factors with a higher explained variance than PCA; PMF provided both the internal analysis and the quantitative analysis. The combination of the two methods can provide more reasonable and reliable results.