Evaluation of potentially toxic elements in soils developed on limestone and lead-zinc mine sites in parts of southeastern Nigeria.

The present study investigated the distribution of elements and potentially toxic elements (PTEs) in soil profiles in the southeastern region of Nigeria, where unrefined and primitive mining practices are common. Soil samples were collected from mine and non-mine sites in Ameka and Nkalagu and analyzed for total elemental concentration using portable X-ray fluorescence (pXRF). The results showed that the Ameka mine-affected soils were heavily polluted, while the Ameka non-mine-affected soils were moderately polluted. The Nkalagu mine and non-mine-affected soils were also moderately polluted. The potential ecological risk (PER) was high in the Ameka mine-affected site due to elevated As, Cu, and Pb levels, while the Ameka non-mine-affected site had a low PER. The enrichment factor (EF) values indicated more enrichment of PTEs in the mine-affected sites compared to the non-mine-affected sites. The geoaccumulation index (Igeo) showed moderate to extreme contamination in the Ameka mine-affected site with Cu, Zn, As, and Pb. In contrast, the Nkalagu mine-affected site had considerably lower contamination. The regression model showed that site characteristics alone were insufficient to explain elements and PTEs distribution, emphasizing the importance of considering soil properties in understanding their spatial patterns. The study highlights the higher concentrations of As, Cu, and Pb in the mine-affected sites compared to the non-mine areas and recommends remediation strategies for these elements and PTEs, especially in the vicinity of mine sites. Further laboratory analysis is recommended to understand the mobility of PTEs with depth for better remediation approaches.

An in-depth human health risk assessment of potentially toxic elements in highly polluted riverine soils, Príbram (Czech Republic).

Environmental pollution by potentially toxic element (PTE) and the associated health risks in humans are increasingly becoming a global challenge. The current study is an in-depth assessment of PTEs including the often studied lead (Pb), manganese (Mn), zinc (Zn), arsenic (As) and the less-studied titanium (Ti), rubidium (Rb), strontium (Sr), zirconium (Zr), barium (Ba) and thorium (Th) in highly polluted floodplain topsoil samples from the Litavka River, Czech Republic. Soil chemical properties including carbon (Cox) and reaction (pH_H2O) together with iron (Fe) were assessed in the same soils. A portable X-ray fluorescence spectrometer (p-XRFS) (Delta Premium) was used to measure the PTEs and Fe contents of the soils. Soil organic carbon and reaction pH were determined following routine laboratory procedures. The concentration level of each PTE was compared against world average and crustal values, with the majority of elements exceeding the aforementioned geochemical background levels. Distributions of the PTEs were mapped. Two pollution assessment indices including enrichment factor (EF) and pollution index (PI) levels were calculated and their means for Zn (43.36, 55.54), As (33.23, 43.59) and Pb (81.08, 103.21) show that these elements were enriched. Zn, As and Pb accounted for the high pollution load index (PLI) levels observed in the study. The EF and PI distribution maps corresponded with the concentration distribution maps for each PTE. On health risk assessment, hazard quotients (HQ) in different human groups varied. Children had the highest HQs for all PTEs than adults (women and men). PTEs with high HQ levels in distinct human groups were As, Zr and Pb. Zirconium is a less likely element to pose a health risk in humans. Nonetheless, it should be kept in check despite its low pollution occurrence.

Multi-geochemical background comparison and the identification of the best normalizer for the estimation of PTE contamination in agricultural soil.

Identifying a suitable geochemical background level (GBL) and an appropriate normalizer is imperative for ensuring soil quality, health, and security. The objective of this study was to identify the appropriate normalizer and suitable GBL for determining PTE enrichment levels in agricultural soils and investigate if there are any statistical differences due to the GBL [World Average Value (WAV) European Average Value (EAV)] used. Forty-nine topsoil samples were obtained from seven agricultural communities in the Frdek-Mstek District (Czech Republic). Portable X-ray fluorescence was used to determine the total PTEs (Cr, Ni, Cu, Y, Ba, Th, As, Pb, and Zn) concentration levels in the soil. Correlation matrix analysis was used to determine the metallic relationship between the PTEs and the normalizers (Al, Fe, Ti, Zr, Sr and Rb). Pollution indices such as contamination factor (CF), geoaccumulation index (Igeo) and enrichment factor (EF) analysis were used to determine the most suitable GBL. Al, Fe, Sr, Ti and Rb strongly correlated with the CF, Igeo and EF, whereas WAV performed better than the other geochemical background (EAV). The results indicated that Rb was the suitable normalizer and WAV was the appropriate GBL for agricultural soil and provided a foundation for evaluating and surveilling soil quality and health in agricultural soil.

Using an ensemble model coupled with portable X-ray fluorescence and visible near-infrared spectroscopy to explore the viability of mapping and estimating arsenic in an agricultural soil.

Increasing concentrations of potentially toxic elements (PTE) in agricultural soils remain a major source of public concern. Monitoring PTEs in an agricultural field with no history of contaminants necessitate adequate analysis utilizing a robust model to accurately uncover hidden PTEs. Detecting and mapping the distribution of soil properties using portable X-ray fluorescence (pXRF) and proximal sensing techniques is not only rapid, but also relatively inexpensive. In this study, an ensemble model, consisting of partial least square regression (PLSR), support vector machine (SVM), random forest (RF) and cubist, was used for the prediction and mapping of soil As content in an agricultural field with no history of pollution. The datasets were collected using pXRF and field spectroscopy techniques. The main goal was to compare the ensemble model to each of the calibration techniques in terms of prediction accuracy of As content in such a field. Other components [e.g., soil organic carbon (SOC), Mn, S, soil pH, Fe] that are known to influence As levels in the soil were also retrieved to assess their correlation with soil As. The models were evaluated using the root mean squared error (RMSECV), the coefficient of determination (R2CV) and the ratio of performance to interquartile range (RPIQ). In terms of prediction accuracy, the ensemble model outperformed each of the individual techniques (R2CV = 0.80/0.75) and obtained the least error margin (RMSECV = 1.91/2.16). Overall, all the predictive techniques were able to detect both low and high estimated values of soil As within the study field, but with the ensemble model resembling the measurements better. The ensemble model, a promising tool as demonstrated by the current study, is highly recommended to be included in future studies for more accurate estimation of As and other PTEs in other agricultural fields.

vis-NIR and XRF Data Fusion and Feature Selection to Estimate Potentially Toxic Elements in Soil.

Soil contamination by potentially toxic elements (PTEs) is intensifying under increasing industrialization. Thus, the ability to efficiently delineate contaminated sites is crucial. Visible-near infrared (vis-NIR: 350-2500 nm) and X-ray fluorescence (XRF: 0.02-41.08 keV) spectroscopic techniques have attracted tremendous attention for the assessment of PTEs. Recently, the application of fused vis-NIR and XRF spectroscopy, which is based on the complementary effect of data fusion, is also increasing. Moreover, different data manipulation methods, including feature selection approaches, affect the prediction performance. This study investigated the feasibility of using single and fused vis-NIR and XRF spectra while exploring feature selection algorithms for the assessment of key soil PTEs. The soil samples were collected from one of the most heavily polluted areas of the Czech Republic and scanned using laboratory vis-NIR and XRF spectrometers. Univariate filter (UF) and genetic algorithm (GA) were used to select the bands of greater importance for the PTE prediction. Support vector machine (SVM) was then used to train the models using the full-range and feature-selected spectra of single sensors and their fusion. It was found that XRF spectra alone (primarily GA-selected) performed better than single vis-NIR and fused spectral data for predictions of PTEs. Moreover, the prediction models that were derived from the fused data set (particularly the GA-selected) enhanced the models' accuracies as compared with the single vis-NIR spectra. In general, the results suggest that the GA-selected spectra obtained from the single XRF spectrometer (for As and Pb) and from the fusion of vis-NIR and XRF (for Pb) are promising for accurate quantitative estimation detection of the mentioned PTEs.

The influence of land-use on tropical soil chemical characteristics with emphasis on aluminium.

Composition of soil vegetation cover and land management directly influences the cycling of chemical elements and is a key factor for soil biogeochemistry and also Al behaviour. Moreover, Al is an important factor limiting the growth of cultural plants. Our results are based on long-term observations of soils translocated from selected small areas of eight 1 ha plots of different land-use gradient, with identical geological, climatic and geographical conditions, located in the North of Congo Basin (near Mbalmayo, Cameroon). The plots are established in primary and secondary forests, cocoa agroforestry systems and a maize field (two plots per habitat). All soil plots were exchanged between each other in two layers; A. 0-5 cm, and B. 5-20 cm of depths. The soil was sampled at the times 0, +3, +6 months, and soil chemical parameters were determined. The most important differences between the particular habitats comprise of vegetation cover as a consequence of the land management. Particular plots differed mainly in their pH, organic C, exchangeable Al and contents of base cations. The most marked trends comprise of significant decrease of pH, increase of Al and decrease of the Ca/Al ratio in A layer after translocation to the agricultural plots. All translocations resulted into rapid loss of organic C and release of Al, which was more obvious when the forest-to-agriculture translocation took place.

Behaviour of aluminium in forest soils with different lithology and herb vegetation cover.

The aim of this study was to determine the content, distribution and behaviour of Al in soils under beech forest with different parent rock, and to assess the role of herbaceous vegetation on soil Al behaviour. We hypothesize that the contents of elements in the soil sorption complex (Al etc.) are strongly influenced by vegetation cover. Also, low molecular mass organic acids (LMMOA) can be considered as an indicator of soil organic matter (SOM) decomposition and vegetation litter turnover. Speciation of LMMOA, nutrition content (PO43-, Ca2+, K+) and element composition in aqueous extracts were determined by means of ion chromatography and inductively coupled plasma - optical emission spectrometry (ICP-OES) respectively. Active and exchangeable pH, sorption characteristics and exchangeable Al (Alex) were determined in BaCl2 extracts by ICP-OES. Elemental composition of parent rocks was assessed by means of X-ray fluorescence spectroscopy. Herb-poor localities showed lower pH, less nutrients (PO43-, Ca2+, K+), less LMMOA, a larger stock of SOM and greater cation exchange capacity. There was also lower mobilisation of Al in organic horizons, which explains the larger pools of Al. Generally, we can conclude that LMMOA, and thus soil vegetation cover, play an important role in the Al soil cycle.

Isotopic Tracing of Thallium Contamination in Soils Affected by Emissions from Coal-Fired Power Plants.

Here, for the first time, we report the thallium (Tl) isotope record in moderately contaminated soils with contrasting land management (forest and meadow soils), which have been affected by emissions from coal-fired power plants. Our findings clearly demonstrate that Tl of anthropogenic (high-temperature) origin with light isotope composition was deposited onto the studied soils, where heavier Tl (ε(205)Tl ∼ -1) naturally occurs. The results show a positive linear relationship (R(2) = 0.71) between 1/Tl and the isotope record, as determined for all the soils and bedrocks, also indicative of binary Tl mixing between two dominant reservoirs. We also identified significant Tl isotope variations within the products from coal combustion and thermo-desorption experiments with local Tl-rich coal pyrite. Bottom ash exhibited the heaviest Tl isotope composition (ε(205)Tl ∼ 0), followed by fly ash (ε(205)Tl between -2.5 and -2.8) and volatile Tl fractions (ε(205)Tl between -6.2 and -10.3), suggesting partial Tl isotope fractionations. Despite the evident role of soil processes in the isotope redistributions, we demonstrate that Tl contamination can be traced in soils and propose that the isotope data represent a possible tool to aid our understanding of postdepositional Tl dynamics in surface environments for the future.

The variations of aluminium species in mountainous forest soils and its implications to soil acidification.

Aluminium (Al) speciation is a characteristic that can be used as a tool for describing the soil acidification process. The question that was answered is how tree species (beech vs spruce) and type of soil horizon affect Al speciation. Our hypotesis is that spruce and beech forest vegetation are able to modify the chemical characteristics of organic horizon, hence the content of Al species. Moreover, these characteristics are seasonally dependent. To answer these questions, a detailed chromatographic speciation of Al in forest soils under contrasting tree species was performed. The Jizera Mountains area (Czech Republic) was chosen as a representative mountainous soil ecosystem. A basic forestry survey was performed on the investigated area. Soil and precipitation samples (throughfall, stemflow) were collected under both beech and spruce stands at monthly intervals from April to November during the years 2008-2011. Total aluminium content and Al speciation, pH, and dissolved organic carbon were determined in aqueous soil extracts and in precipitation samples. We found that the most important factors affecting the chemistry of soils, hence content of the Al species, are soil horizons and vegetation cover. pH strongly affects the amount of Al species under both forests. Fermentation (F) and humified (H) organic horizons contain a higher content of water extractable Al and Al(3+) compared to organo-mineral (A) and mineral horizons (B). With increasing soil profile depth, the amount of water extractable Al, Al(3+) and moisture decreases. The prevailing water-extractable species of Al in all studied soils and profiles under both spruce and beech forests were organically bound monovalent Al species. Distinct seasonal variations in organic and mineral soil horizons were found under both spruce and beech forests. Maximum concentrations of water-extractable Al and Al(3+) were determined in the summer, and the lowest in spring.

Profile distribution and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests.

The behaviour of principal inorganic anions in forest soils, originating mainly from acid deposition, strongly influences the forest ecosystem response on acidification. The aim of this study was to describe seasonal and temporal changes of sulphate and nitrate contents and related soil properties under beech and spruce forests in a region heavily impacted by acidification. The Jizera Mountains area (Czech Republic) was chosen as such a representative mountainous soil ecosystem. Soil samples were collected at monthly intervals from April to October during the years 2008-2010 under both beech and spruce stands. Soil samples were collected from surface fermentation (F) and humified (H) organic horizons, humic (A) organo-mineral horizons and subsurface mineral (B) horizons (cambic or spodic). A deionised water extract was applied to unsieved fresh samples and the content of anions in these extracts was determined by ion chromatography (IC). In the studied soil profiles, the lowest amount of SO(4)(2-) was found in the organo-mineral A horizons under both types of vegetation. Under spruce the highest amount of SO(4)(2-) was determined in mineral spodic (B) horizons, where a strong sorption influence of Fe and Al oxy-hydroxides is expected. Under beech the highest amount was observed in the surface organic F horizons (forest floor). The amount of NO(3)(-) is highest in the F horizons and decreases with increasing soil profile depth under both types of vegetation. A significantly higher amount of NO(3)(-) was determined in soils under the beech stand compared to spruce. For both soil environments - under beech and also spruce stands - we have determined a general increase of water-extractable SO(4)(2-) and NO(3)(-) during the whole monitoring period. The behaviour of SO(4)(2-) and NO(3)(-) in the soils is strongly related to the dynamics of soil organic matter and particularly to the DOC.

Comparison of water-soluble and exchangeable forms of Al in acid forest soils.

Soil acidification promotes Al release from minerals and parent bedrocks; it also affects Al mobilization and speciation. Speciation of KCl extractable and water-extractable Al in forest soils was done by means of HPLC/IC method. Species Al3+ were the most abundant Al forms in the KCl extracts (around 93%). Prevailing Al forms (more than 70%) in aqueous extracts were Al(X)1+, [i.e., Al(OH)2+, Al(SO4)+, AlF2+, Al(oxalate)+, Al(H-citrate)+, etc.] species. It is assumed that most of KCl and water-extractable Al is bound in soil sorption complex (i.e., highly dispersed colloidal fraction of the soil solid phase creating negative charge) where majority of Al exists in the form of Al3+ species. The ECEC values, total carbon content and parameters related to soil organic matter composition (N and S content) have apparent effect on Al speciation. The most toxic Al3+ species are more concentrated in the B horizons compared to the A and E horizons. Aqueous extracts simulate Al release to soil solution under normal conditions; it can thus exhibit the actual Al toxicity. On the other hand, KCl extraction describes a potential threat for case of strong disturbance of natural soil conditions.

Health care reform in six Central European countries. A focus on health economic requirements in the drug pricing and reimbursement processes.

This study gives an overview of the health care reform in six Central European countries after the transition from a central planning system to a regulated market economy. We focused on cost containment policies for drugs, especially the requirements for submitting health economic data in the pricing and/or reimbursement processes. The literature review was supplemented with a survey with decision makers at national health authorities in each country. The study covered Croatia, Czech Republic, Hungary, Poland, Slovakia, and Slovenia. All countries had in common that health economic information was used in reimbursement rather than in pricing processes. Differences between the six countries were mainly variations in the relative importance of health economic data and the presence of explicit requirements and guidelines. Published health economic guidelines exist in two countries and one of the six countries applies a mandatory submission system for a selected range of new drugs. In most of the Central European countries it is more typical that authorities issue a brief list of required data for reimbursement submissions that include health economic information among other data. There is a generally widespread expectation towards more systematic and formalized requirements for health economic and outcomes research data appearing within the next 3-5 years in the region.

Trends in consumption of calcium channel blockers in the Czech Republic during 1993-1999 and comparison with selected countries: drug utilization study.

OBJECTIVE: To determine the patterns of consumption in calcium channel blockers (CCB) groups in the Czech Republic between 1992 and 1999 and make a comparison with selected countries. METHODS: This was part of a drug utilization study using WHO methodology [Anatomical Therapeutic Chemical classification/defined daily doses (ATC/DDD)]. The wholesale data collected by drug distributors were used. Utilization was calculated as the DDDs for 1000 inhabitants per day. In focus was the consumption of short-acting nifedipine. Comparison with wholesale data from Finland, Norway, Germany and Australia was made. RESULTS: There was a decreasing tendency to use short-acting nifedipine in the Czech Republic over the period 1993-1999. Four years after publication of warning evidence, short-acting nifedipine still accounted for 23% of all calcium channel blockers in our country. The abundance of second-generation CCBs increased from less than 1% in 1993 to 43% in 1999. The consumption of short-acting nifedipine in the Czech Republic and Germany is probably three times more frequent than in Nordic countries and Australia. CONCLUSIONS: Consumption of short-acting nifedipine in the Czech Republic 4 years after recognition of its risks still remains very high. This suggests that implementation of clinical trial results to clinical practice is very slow and ineffective.