Multivariate statistical analysis of urban soil contamination by heavy metals at selected industrial locations in the Greater Toronto area, Canada

A good understanding of urban soil contamination with metals and the location of pollution sources due to industrialization and urbanization is important for addressing many environmental problems. The results are reported here of an analysis of the metals content in urban soils samples next toindustrial locations in the Greater Toronto Area (GTA) in Ontario, Canada. Theanalyzed metals are Cr, Mn, Fe, Ni, Cu, Zn, and Pb. Multivariate geostatistcalanalysis (correlation matrix, cluster analysis, principal component analysis) is used to estimate soil chemical content variability. The correlation matrix exhibits a positive correlation with Mn, Fe, Cu, Zn, Cd, and Pb. The principal component analysis (PCA) displays two components. The first component explains the major part of the total variance and is loaded heavily with Cr, Mn, Fe, Zn,and Pb, and the sources are industrial activities and traffic flows. The second component is loaded with Ni, and Cd, and the sources could be lithology andtraffic flow. The results of the cluster analysis demonstrate three major clusters: 1) Mn-Zn, 2) Pb-Cd-Cu and Cr, 3) Fe-Ni. The geo-accumulation index and the pollution load index are determined and show the main I geovalues to be in the range of 0-1.67; the values indicate that the soil samples studied for industrial locations in the GTA are slightly to moderately contaminated with Cr, Fe, Cu, Zn, and Cd, and moderately contaminated with Pb,while Ni, and Mn fall in class "0". Regarding the pollution load ingindex (PLI), the lowest values are observed at stations 6, 7, 9, 10, 11, 12,25, 27 and 28, while the highest values are recorded for stations 1, 5, 6, 13,14, 16, 17, 18, 20, 22 and 24, and very high PLI readings are seen for stations 5, 13, 16, 17, 18, 22 and 24. These data confirm that the type of industries, especially metallurgical and chemical related ones, in the study area, in addition to high traffic flows, are the main sources for soil pollution in the GTA

Symptomatic dry eye disease among university students

Background: Dry eye disease (DED) is a multifactorial condition often characterized by a reduction in tear film quantity or quality. This study aimed to determine the frequency of DED and its associated subjective symptoms among students of Mu’tah University. Methods: In this cross-sectional study conducted at Mu’tah University, Mu’tah, Jordan, from January to April 2022, 489 students completed an online patient-reported DED symptom questionnaire and the ocular surface disease index (OSDI) questionnaire. Moreover, 106 participants underwent clinical examinations using the Schirmer test I and fluorescein tear breakup time (TBUT). Results: Approximately 74.6% of the students self-reported experiencing DED symptoms, and 72.6% had an OSDI score > 12, which is considered the threshold for an abnormal ocular surface. Clinical examinations revealed low Schirmer test scores (< 10 mm) in 26.4% (n = 28) and 25.5% (n = 27) of the right and left eyes, respectively. We observed low TBUT scores (< 5 s) in 19.8% (n = 21) and 18.9% (n = 20) of the right and left eyes, respectively. We noted significant differences between the self-reported DED symptoms and the Schirmer test scores (P = 0.003 for both right and left eyes), TBUT (P < 0.001 for both right and left eyes), and OSDI score (P < 0.001 for each self-reported DED symptom). We observed a weak significant positive correlation between Schirmer test scores and TBUT in the right (r = + 0.30; P = 0.002) and left (r = + 0.34; P < 0.001) eyes; a negligible significant inverse correlation between OSDI scores and Schirmer test scores in the right (r = - 0.24; P = 0.013) and left (r = - 0.23; P = 0.019) eyes; and a negligible significant inverse correlation between the OSDI score and TBUT of the left eye (r = - 0.25; P = 0.011) but not of the right eye (r = - 0.17; P = 0.077). Conclusions: The frequency of DED symptoms in this study was higher than that previously reported based on foreign statistics. The presence of self-reported DED symptoms was significantly associated with higher OSDI scores. Self-reported DED symptoms were more frequent than the abnormalities detected using objective methods. Therefore, a combination of subjective and objective measures may provide a higher diagnostic yield for DED. Further studies are required to confirm this hypothesis

Response of soil bacterial community composition and its associated geochemical parameters to rapid short-term cyclic groundwater-level oscillations: soil column experiments

Groundwater-level oscillations change geochemical conditions, carbon cycling processes and bacterial community composition, and these changes may vary vertically with depth in a soil. In this study, soil column experiments were conducted to explore variations in soil bacterial community composition and its associated geochemical parameters to rapid short-term cyclic groundwater-level oscillations driven by natural fluctuations (NF) and rainfall infiltration (RI) and the results are compared with quasi static (QS) column. Water saturation patterns in vadose and oscillated zones, and oxygen level patterns, soil total organic carbon (TOC) removal rates and soil bacterial community composition in vadose, oscillated and saturated zones were evaluated. Results showed that water saturation and oxygen level oscillated with groundwater level in NF and RI columns. TOC removal rates in RI column were the highest across vadose (~38.4%), oscillated (~35.8%) and saturated (~35.2%) zones. Deltaproteobacteria, which was significantly correlated with TOC removal (p < 0.05), exhibited relatively higher abundances in the vadose and oscillated zones of RI column than those of QS and NF columns. Soil bacterial community structure was dynamic at the class level due to water saturation, oxygen level and TOC removal. TOC removal was the driver to separate distribution of bacterial community structure in the vadose and oscillated zones of RI column from those of QS and NF columns. This study suggests that RI induced rapid short-term cyclic groundwater-level oscillations could significantly influence both soil carbon cycle and bacterial community structure in vadose and oscillated zones

Impact of Protracted War Crisis on Dental Students: A Comparative Multicountry Cross-sectional Study

BACKGROUND: The impact of conflict and war crisis on dental students is poorly understood. Given the prolonged conflicts and political instability in the Arabic-speaking countries, it is crucial to investigate the effect of these conditions on dental students. This study aimed to assess the impact of protracted war on dental students by comparing the personal, university, and wider context challenges they face across war-affected and unaffected countries. METHODS: A cross-sectional study was conducted including a convenience sample of dental students from 13 universities in 12 Arabic-speaking countries. Respondents were those at entry and exit points of their undergraduate dental training. A self-administered paper questionnaire collected anonymized data on sociodemographics, and personal, university, and wider context challenges that students were facing. Multivariable Poisson regression analyses were carried out. RESULTS: The overall response rate was 64.8%. The mean age was 21.2 (standard deviation = 2.1) years, with 68% of participants being female. After adjusting for age and sex, dental students in Arabic-speaking countries affected by protracted war crisis were significantly more likely to report wider context challenges compared to their counterparts in unaffected countries (n = 2448; beta = 1.12; 95% confidence interval: 1.10-1.13; P < 0.001). DISCUSSION: Dental students in Arabic-speaking countries affected by protracted war crisis were more likely to suffer from wider context challenges such as difficulties in attendance due to the deterioration of security and lack of flexibility of teaching time to accommodate the different circumstances induced by the war crisis. Supporting dental students in areas affected by protracted war crises is needed and may include developing online dental education programs

Evaluation of metals that are potentially toxic to agricultural surface soils, using statistical analysis, in northwestern Saudi Arabia

© 2015, Springer-Verlag Berlin Heidelberg. Heavy metals in agricultural soils enter the food chain when taken up by plants. The main purpose of this work is to determine metal contamination in agricultural farms in northwestern Saudi Arabia. Fifty surface soil samples were collected from agricultural areas. The study focuses on the geochemical behavior of As, Cd, Co, Cr, Cu, Hg, Pb and Zn, and determines the enrichment factor and geoaccumulation index. Multivariate statistical analysis, including principle component analysis and cluster analysis, is also applied to the acquired data. The study shows considerable variation in the concentrations of the analyzed metals in the studied soil samples. This variation in concentration is attributed to the intensity of agricultural activities and, possibly, to nearby fossil fuel combustion activities, as well as to traffic flows from highways and local roads. Multivariate analysis suggests that As, Cd, Hg and Pb are associated with anthropogenic activities, whereas Co, Cr, Cu and Zn are mainly controlled by geogenic activities. Hg and Pb show the maximum concentration in the analyzed samples as compared to the background concentration