Compositional-geochemical characterization of lead (Pb) anomalies and Pb-induced human health risk in urban topsoil.

Urban areas are characterized by a constant anthropogenic input, which is manifested in the chemical composition of the surface layer of urban soil. The consequence is the formation of intense anomalies of chemical elements, including lead (Pb), that are atypical for this landscape. Therefore, this study aims to explore the compositional-geochemical characteristics of soil Pb anomalies in the urban areas of Yerevan, Gyumri, and Vanadzor, and to identify the geochemical associations of Pb that emerge under prevalent anthropogenic influences in these urban areas. The results obtained through the combined use of compositional data analysis and geospatial mapping showed that the investigated Pb anomalies in different cities form source-specific geochemical associations influenced by historical and ongoing activities, as well as the natural geochemical behavior of chemical elements occurring in these areas. Specifically, in Yerevan, Pb was closely linked with Cu and Zn, forming a group of persistent anthropogenic tracers of urban areas. In contrast, in Gyumri and Vanadzor, Pb was linked with Ca, suggesting that over decades, complexation of Pb by Ca carbonates occurred. These patterns of compositional-geochemical characteristics of Pb anomalies are directly linked to the socio-economic development of cities and the various emission sources present in their environments during different periods. The human health risk assessment showed that children are under the Pb-induced non-carcinogenic risk by a certainty of 63.59% in Yerevan and 50% both in Gyumri and Vanadzor.

Toxic element contents and associated multi-medium health risk assessment in an area under continuous agricultural use.

Soils and contaminated plants are in the group of significant environmental pathways of human exposure to toxic elements (TEs). This study aimed to assess the soil-to-plant transfer of TEs (Pb, As, Cd, Hg), as well as the plausible health risks via different exposure pathways in the Armavir region of Armenia. The contents of TEs were determined in soil, fruit and vegetable samples using X-ray fluorescence and atomic absorption spectroscopy, respectively, and the soil-to-plant transfer of TEs and induced chronic non-carcinogenic risks were evaluated. The detected TE contents did not exceed the available national and international regulatory levels. Moreover, the evaluated soil-to-plant transfer of these TEs was negligible. The obtained results indicated the absence of a single-element non-carcinogenic risk via one single ingestion pathway. Meanwhile, in the case of multi-food and multi-soil ingestion, the combined non-carcinogenic risk estimates for Pb and As exceeded the precautionary level of 0.1 indicating a low health risk. Similarly, the multi-element hazard index (HI) showed a low level of non-carcinogenic risk through a multi-pathway ingestion. Thus, the outcomes highlighted that there was a need for precautionary measures to prevent plausible health issues for the adult population in Armavir.

Multifractal features of activity concentration and stochastic risk assessment of naturally occurring and technogenic radionuclides in the soil of Yerevan, Armenia.

Spatial patterns and background ranges of naturally occurring radionuclides (NORs) (i.e. U-238, Th-232, K-40) and Cs-137 were studied in the urban soils of Yerevan, the capital city of Armenia. Multifractal Inverse Distance Weighting (MIDW) was used to generate and analyze distribution patterns of radionuclide activities. Based on Fourier transformation of radioactivity data, a spectral analysis was also applied to separate, where possible, background/baseline patterns from local anomalies: two ranges of background values were found to characterise the Yerevan territory. Specifically, in the south and south-east of Yerevan, the lower background ranges of U-238, Th-232 and K-40 comprised in the intervals 2.60-36.42 Bq/kg, 4.04-30.63 Bq/kg and 147.7-396.7 Bq/kg, respectively, were observed in association with the presence of sedimentary formations. In contrast, the higher ones were found, instead, in the central and northern parts of the city where andesite-basalt lavas and ignimbrite tuffs occur. Here, the background values rise to 142.4 Bq/kg, 138.76 Bq/kg and 1502 Bq/kg, respectively. As for the distribution of artificial Cs-137, its baseline levels in Yerevan seem to depend mostly on the global radioactive fallout and some local technogenic sources. Its distribution patterns partially differ from those of NORs. In the framework of this paper, Radium equivalent activity (RaEq), outdoor absorbed dose rate in air (ODRA) and annual effective dose equivalent (AEDEs) were also determined and mapped. They show a good coincidence of their spatial variations with those of NORs. The Monte Carlo simulation was used to assess excess lifetime cancer risk from a stochastic perspective. The related sensitivity analysis revealed that, among NORs, U-238 and Th-232 give the greatest contribution to the total variance (45.7% 42.8%, respectively). In comparison, K-40 has the lowest share (11.3%). Regarding Cs-137, a highly negligible contribution to the onset of health risks (accounting for 0.02%) was observed.

Revealing XRF data quality level, comparability with ICP-ES/ICP-MS soil PTE contents and similarities in PTE induced health risk.

Portable X-ray fluorescence spectroscopy (XRF) was recognized as an efficient and promising tools to study the contents of chemical elements in various media including soils under the impact of anthropogenic activities. However, the quality of data and the equality of chemical elements with other common analytical methods such as aqua-regia extraction vary depending on site, sample conditions, and analysis time. In this study, we examine the adequacy of XRF and ICP-ES/ICP-MS aqua-regia extractable (AR) results obtained for lab-type pretreated samples (N = 15) for Ti, Fe, Mn, Co, V, Pb, Zn, Cu, Cr, Mo, Sr, and As contents in soils under the impact of copper smelter and assess the equality of PTE contents induced health risk. The obtained results suggested that XRF reached definitive data quality level for As, Zn, and Mn and screening (quantitative) data quality level established for Cu, Pb, Fe, Mo, Cr, V, and Ti. Moreover, in some cases (i.e., for Ti) XRF overperformed AR indicating the high efficiency of XRF application when sparingly soluble mineral matrices are presented. At the same time, PTE induced health risk assessment at the established data quality level showed that equality of non-carcinogenic children health risk was observed for As, Zn, Cu, Pb, Mn, and V. The latter indicating the applicability of XRF to generate reliable base for risky sites identification and characterization.

Identification of spatial patterns, geochemical associations and assessment of origin-specific health risk of potentially toxic elements in soils of Armavir region, Armenia.

The study of soil potentially toxic elements (PTE) contents and establishment of the geochemical characterization of areas which have never been studied is of great concern. In 2019, soil survey of the Armavir region (Armenia) was conducted in order to investigate the spatial pattern of PTE, reveal PTE geochemical associations and assess the origin-specific health risks. The application of compositional data analysis and geospatial mapping allowed to identify two clusters of samples. The first cluster was spatially located on volcanic rocks and was represented by Fe, Co, Mn, Ti, Zn, Ba, Pb suggesting a natural origin of PTE in these areas. The second cluster was allocated on the alluvial, deluvial, and proluvial sediments and represented by As, Cu, Cr, Ni. Such combination of elements in the same group indicates the anthropogenic introduction of some quantities of PTE. The latter is confirmed by the presence of outliers and extreme values for As, Cu and Ni, as well as by the spatial colocation of Fe, Mn, Co, Pb, Zn outliers and extreme contents. The health risk assessment showed that for children the multi-elemental non-carcinogenic risk was detected, while for the adults the non-carcinogenic risk and carcinogenic risk were below the allowable level. The detailed study of the risk levels showed that in first cluster comparatively higher risk were observed for Pb, V, Ba, Zn while in the second cluster: Fe, Co, Mn, As, Cr, Cu, Ni. The results indicated the necessity of additional in-depth studies with special focus on bioavailability of PTE.

Yerevan soil radioactivity: Radiological and geochemical assessment.

Spatial pattern of naturally occurring radionuclides (NOR): 226Ra, 232Th, 40K, and artificial 137Cs was studied using soil samples of the multipurpose geochemical survey of the city of Yerevan, capital of Armenia. High purity Ge detector-based gamma spectrometry system was used for the determination of radionuclides activity concentrations in urban soils. A combination of compositional data analysis, geochemical mapping and radiological assessment were applied to reveal potential factors of technologically enhanced natural radioactivity and excess lifetime cancer risk for Yerevan's population due to NOR and artificial 137Cs in the urban environment. Statistical methods with the geochemical mapping revealed the great contribution of soil-forming rocks to NOR distribution in urban soils. The spatial distribution of calculated radiological indices and dose rates levels follows the distribution patterns of NOR. The activity concentration of fallout radionuclide 137Cs was within the range typical for the studied altitudes. Above baseline activity of 137Cs was observed in the north-western and western part of the city that is in typical ranges of 137Cs content in soil derived from global radioactive fallout. Urban soils of Yerevan were found radiologically safe, however, igneous rock derived soils are a sink of NOR and the main environmental source of continuous exposure to the residents. Values of excess lifetime cancer risk were higher than mean global value.

Combination of compositional data analysis and machine learning approaches to identify sources and geochemical associations of potentially toxic elements in soil and assess the associated human health risk in a mining city.

Mining activities change the chemical composition of the environment and have negative reflection on people's health and there is no single measure to deal with adverse consequences of mining activities, as each case is specific and needs to be understood and mitigated in a unique way. In this study, the combination of compositional data analysis (CoDA), k-means algorithm, hierarchical cluster analysis applied to reveal the geochemical associations of potentially toxic elements (PTE) in soil of Alaverdi city (Armenia) (Ti, Fe, Ba, Mn, Co, V, Pb, Zn, Cu, Cr, Mo, As). Additionally, to assess PTE-induced health risk, two commonly used approaches were used. The obtained results show that the combination of CoDA and machine learning algorithms allow to identify and describe three geochemical associations of the studied elements: the natural, manmade and hybrid. Moreover, the revealed geochemical associations were linked to the natural pattern of distribution of the element concentrations including the influence of the natural mineralization of the parent rocks, as well as the emission from the copper smelter and urban management related activities. The health risk assessment using the US EPA method demonstrated that the observed contents of studied elements are posing a non-carcinogenic risk to children in the entire territory of the city. In the case of adults, the non-carcinogenic risk was identified in areas situated close to the copper smelter. The Summary pollution index (Zc) values were in line with the results of the US EPA method and indicated that the main residential part of the city was under the hazardous pollution level suggesting the possibility of increase in the overall incidence of diseases among frequently ill individuals, children with chronic diseases and functional disorders of vascular system. The obtained results indicated the need for further in-depth studies with special focus on the synergic effect of PTE.

Continuous impact of mining activities on soil heavy metals levels and human health.

Soils samples collected during different geochemical surveys of the city of Kajaran located near the biggest Cu-Mo mining area in Armenia were subjected to the multivariate geostatistical analysis and geochemical mapping in order to reveal soil heavy metals spatial distribution pattern and assess human health risk level under continuous impact of mining activities. In addition, human health risk assessment was done for the contents of Pb, Cu, Zn, Co, Mo, Mn, Ti, and Fe. The results of Principal Component Analysis and Cluster Analysis verify each other and were also complemented by the spatial distribution features of studied heavy metals indicating that two groups of elements have been generated. The first anthropogenically predominated group includes the main industrial elements Mo and Cu, and their accessories Pb and Zn while Ti, Mn, Fe and Co with the naturally predominant contents were observed in the second group. Moreover, the study reveals that the superposition of geogenic and anthropogenic components lead to the alteration of the shapes of areas with the high natural contents of heavy metals and formation of polluted areas with the intensive anomalies of elements. Health risk assessment showed that Mo was the only studied element which poses a non-carcinogenic risk to adult and children's health in some sampling sites during the whole period of investigations. Moreover, in all studied locations multi-elemental non-carcinogenic risk to children health from all studied heavy metals were detected. Special attention was given to the soils of kindergarten territories, and the results indicated that Hazard Index in kindergartens was >1 indicating an adverse health effect to children. The results obtained can serve as a basis for the development and implementation of risks reduction measures and systematic monitoring program planning.

Human health risk assessment and riskiest heavy metal origin identification in urban soils of Yerevan, Armenia.

The pollution of urban soils by heavy metals remains a topical issue because of the risks it represents to human health. Heavy metal pollution levels of Yerevan's soils were evaluated using Pollution index and Enrichment factor, while associated health risk was assessed by US EPA model. The heavy metals with significant amount of PI > 1 values were observed for V (100%), Cr (95.4%), Ni (92.5%), Cu (95.6%), Zn (92.9%), Hg (89.0%), Pb (99.9%), As (72.0%), and Ba (61.6% of samples). EF showed that Yerevan topsoils were significantly contaminated with Hg, and moderately contaminated with V, Ni, Cu, Zn, Cr, and As. Topsoils near the smelting plants of molybdenum concentrate have moderately to extremely high contamination levels for Mo. Topsoils were moderate to extremely highly contaminated with Pb, too. The high amounts of samples with heavy metal contents greater than Maximum Acceptable Concentrations were observed for Pb, Cr, Zn, Ni, and Cu. Pb and Cr exceeded corresponding Soil Screening Levels in 3.39% and 2.43% of samples, correspondingly. The risk assessment showed children's multi-elemental non-carcinogenic risk and low level of arsenic carcinogenic risk in the whole Yerevan. The riskiest element was Pb which high contents in 72 risky sites correlate only with the metals having a natural origin. Moreover, its main source is historically polluted soils and Pb supposed to be redistributed in the city environment linked to the sorption complexes of Fe and Mn oxides.

Heavy metals pollution levels and children health risk assessment of Yerevan kindergartens soils.

Children, the most vulnerable urban population group, are exceptionally sensitive to polluted environments, particularly urban soils, which can lead to adverse health effects upon exposure. In this study, the total concentrations of Ag, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Ti, V, and Zn were determined in 111 topsoil samples collected from kindergartens in Yerevan. The objectives of this study were to evaluate heavy metal pollution levels of kindergarten's soils in Yerevan, compare with national legal and international requirements on heavy metal contents in kindergarten soil, and assess related child health risk. Multivariate geostatistical analyses suggested that the concentrations of Ag, As, Ba, Cd, Cu, Hg, Mo, Pb, and Zn observed in the kindergarten's topsoil may have originated from anthropogenic sources, while Co, Cr, Fe, Mn, Ni, Ti, and V mostly come from natural sources. According to the Summary pollution index (Zc), 102 kindergartens belong to the low pollution level, 7 to the moderate and only 2 to the high level of pollution. Summary concentration index (SCI) showed that 109 kindergartens were in the allowable level, while 2 featured in the low level of pollution. The health risk assessment showed that in all kindergartens except for seven, non-carcinogenic risk for children was detected (HI>1), while carcinogenic risk from arsenic belongs to the very low (allowable) level. Cr and multi-element carcinogenic risk (RI) exceeded the safety level (1.0E- 06) in all kindergartens and showed that the potential of developing cancer, albeit small, does exist. Therefore, city's kindergartens require necessary remedial actions to eliminate or reduce soil pollution and heavy metal-induced health risks.