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.

Temporal variability of environmental indicators for agriculture in Albania.

This study aimed to reveal the trends in soil nutrient (NPK) balances for agricultural land in Albania for the period 1950-2019, through the analysis of the main NPK sources to NPK inputs and outputs. The results showed a large temporal variation in the balances of these nutrients, especially nitrogen. This variability depends mainly on the dynamics of land use change, the amount of chemical fertilizers used, and the number of animals during study period. For all three soil nutrients, negative trends have been observed in their balance sheets. From 1950 to 1990, the negative balance has declined, returning to positive for nitrogen in 1990 and phosphorus between 1970 and 2000, but has increased again in the last two to three decades. For 2019, the deficit for N was -104.8 kg ha1, for P -8.7 kg ha-1, and for K -134.5 kg ha-1, making Albania have the largest deficit of soil nutrients compared to EU and OECD countries. This deficit is mainly due to the application of small amounts of chemical fertilizers. In this context, the increase in crop yields in the last two decades seems to be related more to the improvement of plant production technologies than to the increase in the use of nitrogen and potassium fertilizers. Currently, there appears to be no environmental pressure or potential risk of pollution at nationwide scale. However, this risk may exist at regional and field scales. Therefore, the assessment of soil nutrient balance at these two scales is necessary.

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

The study analysed the content of heavy metals in surface soil and sediment samples from the Bregu i Matit Plain in NW Albania in relation to irrigation in order to evaluate the soil pollution and the potential risk to human health. Evaluation of soil pollution was performed using the enrichment factor and geo-accumulation index. Contents of cadmium, chromium and nickel of irrigated soils were significantly higher than those of non-irrigated soil, while contents of lead (in three of the irrigated locations), zinc and arsenic (in one of the irrigated locations) were significantly lower. Correlation analysis (CA) and principal component analysis (PCA) indicated that the primary source of the first three metals was irrigation, and the last three metals were originated from other anthropic sources, like the use of chemicals, etc. Enrichment factor (E f) calculation showed that irrigated soils were most enriched in cadmium, chromium, copper and nickel. Index of geo-accumulation (I geo) revealed that arable soils of Bregu i Matit are unpolluted to moderately polluted with cadmium, chromium, copper and zinc and moderately to strongly polluted with nickel and arsenic. The presence of heavy metals in the studied soils indicates a potential risk of transfer of these elements in the food chain. Therefore, further studies on the speciation of heavy metals in the studied soils in order to evaluate their mobility are needed.

Pedogenesis and nickel biogeochemistry in a typical Albanian ultramafic toposequence.

This study aimed at relating the variability of Ni biogeochemistry along the ultramafic toposequence to pedogenesis and soil mineralogy. Hypereutric Cambisols dominate upslope; Cambic Vertisols and Fluvic Cambisols occur downslope. The soil mineralogy showed abundance of primary serpentine all over the sequence. It is predominant upslope but secondary smectites dominate in the Vertisols. Free Fe-oxides are abundant in all soils but slightly more abundant in the upslope soils. Whereas serpentines hold Ni in a similar and restricted range in every soil (approx. 0.3 %), Ni contents in smectites may vary a lot and Mg-rich and Al-poor smectites in the Vertisol could hold up to 4.9 % Ni. Ni was probably adsorbed onto amorphous Fe-oxides and was also exchangeable in secondary smectites. High availability of Ni in soils was confirmed by DTPA extractions. However, it varied significantly along the toposequence, being higher in upslope soils, where Ni-bearing amorphous Fe-oxides were abundant and total organic carbon higher and sensibly lower downslope on the Vertisols: NiDTPA varied from 285 mg kg(-1) in the surface of soil I (upslope) to 95.9 mg kg(-1) in the surface of Fluvic Cambisols. Concentration of Ni in Alyssum murale shoots varied from 0.7 % (Hypereutric Cambisols) to 1.4 % (Hypereutric Vertisol). Amazingly, Ni uptake by A. murale was not correlated to NiDTPA, suggesting the existence of specific edaphic conditions that affect the ecophysiology of A. murale upslope.

Heavy metals in soils from Tirana (Albania).

This study was aimed to establish background and reference values of total heavy metals in soils from a representative area of Albania (Tirana). Thirty-eight soil samples collected from genetic horizons of major soil types of Tirana were analyzed for important physicochemical properties by standard methods and for total contents of Cd, Cr, Ni, Pb, Zn, and Cu by atomic absorption spectrometer, after extraction with aqua regia. The results showed that the total contents of Cd, Cr, Ni, Pb, Zn, and Cu in surface horizons varied widely with respective mean values of 0.3 (± 0.6), 174.2 (± 63.7), 305.9 (± 133.0), 19.7 (± 12.4), 95.5 (± 26.3), and 42.7 (± 6.8) mg/kg. The highest metal contents were found in two soils developed in limestone. The depth distribution of metals showed a tendency for accumulation of Cd and Pb in the surface horizons of three soils, suggesting that these metals partially come from anthropogenic inputs. Correlation analysis indicated that the metal contents of soils were controlled by soil properties, including pH, CaCO3, clay, organic matter, cation exchange capacity, and Fe oxides. The background values (given as the 90th percentile) were much higher than those reported in the literature, showing that the levels of respective metals were naturally higher. The total metal contents of some soils were above background levels, suggesting metal pollution. The reference values for all the analyzed metals were quite consistent with those of the Dutch system. The proposed background and reference values can be used to evaluate the soil pollution with these elements.