V. Simeonov

Assessment of metal pollution based on multivariate statistical modeling of ‘hot spot’ sediments from the Black Sea

The paper deals with application of different statistical methods like cluster and principal components analysis (PCA), partial least squares (PLSs) modeling. These approaches are an efficient tool in achieving better understanding about the contamination of two gulf regions in Black Sea. As objects of the study, a collection of marine sediment samples from Varna and Bourgas hot spots gulf areas are used. In the present case the use of cluster and PCA make it possible to separate three zones of the marine environment with different levels of pollution by interpretation of the sediment analysis (Bourgas gulf, Varna gulf and lake buffer zone). Further, the extraction of four latent factors offers a specific interpretation of the possible pollution sources and separates natural from anthropogenic factors, the latter originating from contamination by chemical, oil refinery and steel-work enterprises. Finally, the PLSs modeling gives a better opportunity in predicting contaminant concentration on tracer (or tracers) element as compared to the one-dimensional approach of the baseline models. The results of the study are important not only in local aspect as they allow quick response in finding solutions and decision making but also in broader sense as a useful environmetrical methodology.

Ten years trends (1984–1993) in the precipitation chemistry in central Austria

Abstract Since 1984, wet precipitation samples have been collected from five sampling sites in the eastern Alpine region of Austria. The chemical analysis performed included pH, NH4+, Na+, K+, Ca2+, Mg2+, Cl−, NO3− SO42− and precipitation amount. These data were used to determine the 10 years (1984–1993) trends in precipitation chemistry and deposition for all major ions. The statistical data treatment by the use of least-squares linear regression revealed a significant decrease of sulfate and hydrogen ion concentrations and depositions at all sites in consideration (above 65% for hydrogen ion and over 33% for sulfate concentration and 40% for hydrogen and 36% for sulfate deposition). An effort is made to explain the acidity decrease not only by the parallel decrease of sulfate concentration but by the participation of the other constituents of the wet precipitation events. It has been found that when the hydrogen ion concentration decrease is stronger than that of sulfate ion concentrations a compensation mainly by ammonium ion concentration increase is achieved. On the contrary, when the hydrogen ion concentration decrease is weaker than sulfate concentration decrease, a calcium ion concentration decrease is present for the sites in consideration. The results obtained indicate that the precipitation chemistry in Central Austria follows the global trends of controlled reduction of atmospheric acidity.

Determination of mercury by electrothermal atomic absorption spectrometry using different chemical modifiers or a slurry technique

The applicability of different chemical modifiers for thermal stabilization and ETAAS determination of mercury is studied. The modifier effect is strongly influenced by the type of acid and acid content in the sample solution. A method is described for mercury determination in tuna fish and sediment after high pressure digestion with nitric acid, using thioacetamide (TAC) as chemical modifier. The method permits determination of 0.5 µg g–1 mercury. A simpler and faster procedure using a slurry technique for the determination of mercury in reference materials (tuna fish, spinach, cabbage and sediments) was also evaluated. Optimal instrumental parameters for mercury determination in slurries are presented. On the basis of the results obtained a new procedure which allows determination of 0.1 µg g–1 mercury was developed.

CHEMOMETRICAL ANALYSIS OF WASTE WATER MONITORING DATA FROM YANTRA RIVER BASIN, BULGARIA

A chemometrical study of waste water data is carried out in order to reveal some new information about the pollution events in Yantra river basin, Bulgaria. Cluster analysis shows that no substantial difference in the behaviour of various sites along the river could be found if all chemical pollutants are simultaneously considered as variables (both for direct and indirect inlet of pollutants). Further, the clustering of the variables indicates a separation between organic and nutrition polluting species. The principal components analysis offered information about the latent factors influencing the data structure. In principle, three to four such latent factors explain over 80% of the total variance of the system. These factors are conditionally named “organic pollution”;, “nutrition pollution”; or “natural”; and are slightly different for the cases of direct and indirect inlet.

CHEMOMETRICAL CLASSIFICATION OF BIOMONITORING ANALYTICAL DATA FOR HEAVY METALS .PART I. TREES (LEAVES) AS BIOINDICATORS

The present paper deals with chemometric interpretation of the bioindicating ability of mosses for heavy metal pollution in urban and rural areas of Greece. Fourteen different moss species collected at twelve sampling sites are included in the study. Four heavy metals concentrations (lead, zinc, copper and cadmium) are determined in each of the totally 61 various samples (with respect to plant speciation and site characteristics). Cluster and principal components analysis are applied as classification and display approaches to reveal, on one hand, specific information about mosses specificity towards pollution species and, on the other hand, response of the sampling location towards bioindication by the use of mosses. It is shown that no specific differentiation with respect to the biotope or mosses’ family is proved probably, due to lack of sampling design strategy rather than to equal bioindicator response or similar ecological situation in the regions of sampling. Specific detection is proved mainly in...

Time trends in the concentrations of lead in wet precipitation from rural and urban sites in Austria

Trend and time series analysis of concentrations of lead in wet precipitation at different rural and urban sampling sites in Austria, collected during intervals of 6-12 years (between 1984 and 1995) is performed. A substantial decrease of the lead concentrations for all sites in consideration is observed similar to observations in Germany, Sweden and North sea and western Atlantic regions. Reductions in rural sites between 60 and 80% in 10 years and around 90% in 10 years in urban areas are found. This trend correlates with the reduction of lead emissions from combustion of gasoline. The seasonal deconvolution model of the data set reveals a typical seasonality with lead concentration peaks in summer and spring for the rural sites and winter peaks for urban sites. The average annual lead concentration in the rural region for 1995 was 1.25 micrograms/l, in the urban region 2.25 micrograms/l.

Chemometrical interpretation of analytical data for vertical distribution of some chemical components in sea water

SummaryAnalytical data for vertical distribution (depth profile) of components in sea water are interpreted by the use of multivariate statistical methods (principal components analysis, correspondence factor analysis and cluster analysis). The various chemical components (NH3, P, Zn, Mn, Cu, Fe, O2, pH, salinity and alkalinity) and some physical characteristics (Eh, T, suspended matter) or the depths of sampling (from 0 to 200 m) are classified as objects of similarity. Two principal components are identified as possible really existing natural factors determining the vertical distribution of the components in the sea water phase.

Distribution and correlation of elements in waters, suspensions, sediments and marine organisms from the black sea

The distribution of several ecologically important elements in Black Sea waters, suspensions, sediments and organisms was studied. The correlation analysis of the data carried out reveals a higher level of correlation along the natural process of elemental accumulation: from waters and suspended matter to the thin surface layer and, then, to sediments and living organisms. According to this conclusion a suggestion is made to perform anthropogenic studies in the marine environment mainly on sediment or biological samples where pollutants distribution can be effectively proven.

Interpretation of geochemical data by the use of multivariate data analysis

Different strategies of multivariate data analysis are used to interpret a data base from geological samples. Cluster and correspondence analysis are applied to classify properly 34 chemical elements from 10 representative rock samples (volcanic series from Borovitsa, Rhodopa mountains, Bulgaria). Principal components analysis is also used as display method to visualize the relation between the variables and objects of interest. The multivariate data analysis applied makes it possible to interpret the origin and orogenesis of the samples.

Chemometric study of atmospheric wet and dry precipitates from an urban region

Data from chemical analysis of rain water and aerosol samples collected in a large urban area have been treated by the use of chemometrical approaches. An attempt has been made to compare, on the one hand, various data treatment techniques (constituent ratios, correlation analysis, principal component analysis and principal component/multiple regression analysis) and, on the other, the formation mechanism of both types of precipitation. It is shown that the multivariate statistical approach reveals a new level of information concerning chemical sources and interactions in wet and dry atmospheric events. Substantial factors have been established to regulate the formation of the rain water and air‐particulate during different sampling seasons. It has been postulated that both types of precipitate formed in a large seaside urban atmosphere characterized by serious pollutants reveal different response to the atmospheric processes.