scholarly journals Ανάλυση περιβαλλοντικού κινδύνου από βαρέα μέταλλα γεωγενούς και ανθρωπογενούς προέλευσης σε δύο αντιπροσωπευτικές περιοχές του Ελλαδικού χώρου

2016 ◽  
Author(s):  
Δήμητρα Μεγαδούκα
Keyword(s):  
Principal Component Analysis ◽  
Cluster Analysis ◽  
Factor Analysis ◽  
Hierarchical Cluster Analysis ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Component Analysis ◽  
Η Factor

Σκοπός της παρούσας μελέτης είναι η έρευνα έξι βαρέων μετάλλων σε δύο περιοχές του Ελλαδικού χώρου. Οι κεντρικοί άξονες της έρευνας αυτής αποτελούνται από τους εξής στόχους: i) να προσδιοριστούν οι συγκεντρώσεις των μετάλλων Pb, Cd, Zn, Co, Ni και Cr που εντοπίζονται σε αδιατάρακτα εδάφη, ii) να προσδιοριστούν οι πηγές προέλευσης των μετάλλων (ανθρωπογενής – γεωγενής) με εργαστηριακές και στατιστικές μεθόδους, iii) να προσδιοριστούν οι γεωχημικές μορφές των μετάλλων που κατανέμονται στα εδάφη, iv) να παρουσιαστούν γεωγραφικοί χάρτες κατανομής των μετάλλων με την χρήση του προγράμματος Γεωγραφικών Πληροφοριακών Συστημάτων, v) να προσδιοριστούν οι υποβόσκουσες σχέσεις μεταξύ των μετάλλων vi) να γίνει εκτίμηση περιβαλλοντικού κινδύνου που σχετίζεται με την ρύπανση εδαφών από βαρέα μέταλλα σε περιοχές επιβαρυμένες από ανθρωπογενή και γεωγενή αίτια.Επιλέχθηκαν δύο περιοχές μελέτης. α) Η Βόρεια Εύβοια επιλέχθηκε ως περίπτωση επιβάρυνσης από βαρέα μέταλλα γεωγενούς προέλευσης λόγω μητρικού υλικού - των βασικών και υπερβασικών πετρωμάτων που χαρακτηρίζουν γεωλογικά την περιοχή. β) Η Λαυρεωτική χερσόνησος επιλέχθηκε ως περίπτωση επιβάρυνσης από βαρέα μέταλλα ανθρωπογενούς προέλευσης από τις παλαιότερες (π.Χ.) αλλά και πρόσφατες μεταλλευτικές και μεταλλουργικές δραστηριότητες.Στην περιοχή της Βόρειας Εύβοιας επιλέχθηκαν 21 θέσεις δειγματοληψίας και στην Λαυρεωτική χερσόνησο επιλέχθηκαν 45 θέσεις δειγματοληψίας. Από κάθε θέση δειγματοληψίας, συλλέχθηκαν δείγματα από δύο διαφορετικά βάθη, 0-10 cm (Α) και 10-30 cm (Β). Σε όλα τα εδαφικά δείγματα προσδιορίστηκαν οι εξής φυσικοχημικές ιδιότητες των εδαφών : η κοκκομετρική σύσταση, το pH, το Eh, η οργανική ουσία και το ισοδύναμο CaCO3. Επίσης προσδιοριστήκαν οι μορφές των μετάλλων με την μέθοδο διαδοχικών εκχυλίσεων τροποποιημένη BCR. Η μέθοδος των διαδοχικών εκχυλίσεων στοχεύει επιλεκτικά και απελευθερώνει τα μέταλλα που είναι συνδεδεμένα σε : α) υδατοδιαλυτές & συνδεδεμένες με ανθρακικά άλατα, β) οξείδια Fe και Mn, γ) οργανική ουσία και δ) πυριτικές μορφές. Επίσης, για να γίνει μία σωστή και αντικειμενική σύγκριση των αποτελεσμάτων και να προσδιοριστούν οι σχέσεις μεταξύ των μετάλλων χρησιμοποιήθηκε το πρόγραμμα Factor Analysis (ανάλυση παραγόντων) και το πρόγραμμα Hierarchical Cluster Analysis. Η Factor Analysis με την μέθοδο της Principal Component Analysis, προσδιορίζει έναν μικρό αριθμό παραγόντων που εξηγούν το μεγαλύτερο μέρος της διακύμανσης που παρατηρείται, σε έναν πολύ μεγαλύτερο όγκο δεδομένων, ενώ η Hierarchical Cluster Analysis προσδιορίζει τις μεταβλητές ή τους παράγοντες, οι οποίοι εξηγούν τον τρόπο που συσχετίζονται τα μέταλλα απεικονιζόμενες σε ένα δενδρόγραμμα.

scholarly journals Groundwater quality assessment using principal component analysis and hierarchical cluster analysis in Alaçam, Turkey

2021 ◽  
Author(s):  
Mehmet Taşan ◽  
Yusuf Demir ◽  
Sevda Taşan
Keyword(s):  
Principal Component Analysis ◽  
Cluster Analysis ◽  
Groundwater Quality ◽  
Seawater Intrusion ◽  
Hierarchical Cluster Analysis ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Component Analysis ◽  
Quality Parameters ◽  
Multivariate Statistical

Abstract This study assessed groundwater quality in Alaçam, where irrigations are performed solely with groundwaters and samples were taken from 35 groundwater wells at pre and post irrigation seasons in 2014. Samples were analyzed for 18 water quality parameters. SAR, RSC and %Na values were calculated to examine the suitability of groundwater for irrigation. Hierarchical cluster analysis and principal component analysis were used to assess the groundwater quality parameters. The average EC value of groundwater in the pre-irrigation period was 1.21 dS/m and 1.30 dS/m after irrigation in the study area. It was determined that there were problems in two wells pre-irrigation and one well post-irrigation in terms of RSC, while there was no problem in the wells in terms of SAR. Piper diagram and cluster analysis showed that most groundwaters had CaHCO3 type water characteristics and only 3% was NaCl- as the predominant type. Seawater intrusion was identified as the primary factor influencing groundwater quality. Multivariate statistical analyses to evaluate polluting sources revealed that groundwater quality is affected by seawater intrusion, ion exchange, mineral dissolution and anthropogenic factors. The use of multivariate statistical methods and geographic information systems to manage water resources will be beneficial for both planners and decision-makers.

scholarly journals Analysis of the procedures used in the forensic evaluation of illegal substances: a statistical approach to interpreting reports

2019 ◽  
Vol 8 (1) ◽  
pp. 7-23
Author(s):  
Aline Thaís Bruni ◽  
Ricardo Luís Yoshida ◽  
Arthur Serra Lopes Ferreira ◽  
Jesus Antonio Velho ◽  
Bruno Spinosa De Martinis ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Cluster Analysis ◽  
Least Squares ◽  
Partial Least Squares ◽  
Hierarchical Cluster Analysis ◽  
Labor Demand ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Component Analysis ◽  
Final Report

ResumoEste estudo utilizou ferramentas estatísticas para avaliar laudos forenses sobre substâncias ilegais. Avaliamos variáveis quanto às características da análise e abordamos a metodologia empregada pelos peritos. Perguntas baseadas no que é necessário para esclarecer a lei foram formuladas. Analisamos 1008 documentos oficiais de diferentes jurisdições, divididos em 504 conjuntos compostos por um laudo preliminar e um laudo definitivo para cada caso. Os laudos foram examinados por uma equação empírica formulada para fornecer um parâmetro denominado “Report Relevance” (Relevância do Laudo), que teve por finalidade classificar cada documento de acordo com uma pontuação relacionada à quantidade de informação contida. A validação do método foi realizada por análise multivariada de dados: Análise de Componentes Principais (Principal Component Analysis, PCA), Análise de Agrupamentos Hierárquicos (Hierarchical Cluster Analysis, HCA), Soft Independent Modeling of Class Analogy (SIMCA) e Mínimos Quadrados Parciais (Partial Least Squares, PLS). A análise quantitativa mostrou que os documentos foram bem produzidos, com boa qualidade, uma vez que a Relevância do Laudo apresentou valores em torno de 0,74 ± 0,08 para aqueles provenientes da Polícia Estadual. Em comparação, os documentos provenientes da Polícia Federal obtiveram valores em torno de 0,87 ± 0,05. Fatores que podem explicar essas diferenças e as melhores pontuações para os laudos federais incluem maior investimento em tecnologia e treinamento de pessoal, e menor demanda de mão-de-obra e rotina. Para ambas as forças policiais, alguns aspectos poderiam ser melhorados, como imagens das evidências coletadas ou procedimentos analíticos laboratoriais. Finalmente, a metodologia neste estudo pode ser adaptada para ser usada em outros tipos de investigação forense.Palavras-chave: Substâncias Ilícitas, Procedimentos Periciais, Análise MultivariadaAbstractThis study used statistical tools to evaluate forensic reports on illegal substances. We evaluated variables regarding the characteristics of the analysis and we addressed the methodology employed by the experts. Questions based on what is required to clarify the law were formulated. We have parsed 1008 official documents from different jurisdictions, divided into 504 sets comprised of a preliminary and a final report for each case. The reports were examined by an empirical equation formulated to provide a parameter called “Report Relevance”, which intended to classify each report according to a score related to the amount of information it contained.  The validation of the method was performed by multivariate data analysis: Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), Soft Independent Modeling of Class Analogy (SIMCA) and Partial Least Squares (PLS). Quantitative analysis showed that the expert documents were well produced, with good quality, since the Report Relevance showed values around 0.74 ± 0.08 for the reports from the State Police. By comparison, reports from the Federal Police obtained scores around 0.87 ± 0.05. Factors that might explain these differences and the better scores for the Federal reports include increased investment in technology and training of staff, and a lower labor demand and routine. For both police forces, some aspects could be improved, such as images of the collected evidence or laboratory analytical procedures. Finally, the methodology in this study can be adapted to be used in other kinds of forensic investigation.Keywords: Illegal Substances, Expertise Procedures, Multivariate Analysis.  

scholarly journals Analysis of Geomagnetic Ap Index on Worldwide Earthquake Occurrence using the Principal Component Analysis and Hierarchical Cluster Analysis

2021 ◽  
Vol 50 (4) ◽  
pp. 1157-1164
Author(s):  
Nur Hidayah Ismail ◽  
Nazhatulshima Ahmad ◽  
Nur Anisah Mohamed ◽  
Mohammad Redzuan Tahar
Keyword(s):  
Principal Component Analysis ◽  
Cluster Analysis ◽  
Hierarchical Cluster Analysis ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Component Analysis ◽  
Research Centre ◽  
Before And After ◽  
Solar Events ◽  
Ap Index

Geoeffective solar events, especially the coronal mass ejection (CME) and the high-speed solar wind (HSSW) will induce geomagnetic storm upon its arrival to Earth. The solar events could trigger an earthquake occurred during the arrival. In this study, the focus is on the proxy of the geoeffective solar events, which is the geomagnetic Ap index and the data of shallow worldwide earthquakes. The main objective was to investigate the impact of geomagnetic storms on the occurrences of earthquakes from 1994 to 2017 from a statistical perspective. The geomagnetic Ap index data was obtained from the Helmholtz-Centre Postdam - GFZ German Research Centre for Geosciences and the shallow worldwide earthquake data were from the United States Geological Survey (USGS) earthquake catalogue. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were used to analyse the data. Two groups were obtained from the PCA biplot: Group 1 - before the event (Day-4 to Day-1) and Group 2 - after the event group (Day 0 to Day+4). A two-cluster solution was obtained from the HCA, which shows that days before and after geostorm are divided into two main clusters. The statistical results show that earthquakes activity might have different behaviour before and after the geostorm occurred. In conclusion, the results emphasize that there are differences between days before and after the geostorm occurrence, hence, the solar influence upon earthquake occurrences cannot be neglected entirely.

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