Persistent organic pollutants (POPs) in edible fish species from different fishing zones of Croatian Adriatic.

High-risk contaminants, OCPs and PCBs, were investigated in marine fish from the Adriatic Sea, from which retail fish in Croatia is commonly sourced. The pollutant levels in sardine, horse and chub mackerel, anchovy and round sardinella were analysed based on a two-year sampling and the joint use of generally accepted statistics and advanced clustering methods - self-organizing maps (SOM) and decision tree analysis (DT). Both the SOM and DT suggested fish mass and length rather than fat along with α-HCH, p,p'-DDT, PCB-74 and PCB-189 to cause variable pollutant uptake among species. Main distinctions of sardines occur in coastal and off coast regions rather than in a particular fishing zone and they are associated with both fish characteristics, levels of γ-HCH and PCBs: -60, -105, -150, -170, and -189. The results, mutually compatible or in agreement, could be useful for the design and implementation of the abatement strategies of fish pollution.

Assessment of spatial and temporal variations in trace element concentrations using honeybees (Apis mellifera) as bioindicators.

With the increase in anthropogenic activities metal pollution is also increased and needs to be closely monitored. In this study honeybees were used as bioindicators to monitor metal pollution. Metal pollution in honeybees represents pollution present in air, water and soil. Concentrations of As, Cs, Hg, Mo, Sb, Se, U and V were measured. The aim of this study was to assess spatial and temporal variations of metal concentrations in honeybees. Samples of honeybees were taken at five different regions in Serbia (Belgrade - BG, Pancevo - PA, Pavlis - PV, Mesic - MS, and Kostolac - TPP) during 2014. Spatial variations were observed for Sb, which had higher concentrations in BG compared to all other regions, and for U, with higher concentrations in the TPP region. High concentrations of Sb in BG were attributed to intense traffic, while higher U concentrations in the TPP region are due to the vicinity of coal fired power plants. In order to assess temporal variations at two locations (PA and PV) samples were taken during July and September of 2014 and June, July, August and September of 2015. During 2014 observing months of sampling higher concentrations in July were detected for Sb and U in BG, which is attributed to lifecycle of plants and honeybees. During the same year higher concentrations in September were observed for As, Sb in PA and Hg in PV. This is due to high precipitation during the peak of bee activity in spring/summer of 2014. No differences between months of sampling were detected during 2015. Between 2014 and 2015 statistically significant differences were observed for Hg, Mo and V; all elements had higher concentrations in 2014. This is in accordance with the trend of reduction of metal concentrations in the bodies of honeybees throughout the years in this region.

Honeybees as sentinels of lead pollution: Spatio-temporal variations and source appointment using stable isotopes and Kohonen self-organizing maps.

In this study, honeybees were used to determine spatio-temporal variations and origin sources of Pb. Lead concentrations and isotopic composition were used in combination with selected statistical methods. The sampling was carried out at five different locations in Serbia: urban region (BG), petrochemical industry (PA), suburban region (PV), rural region (MS) and thermal power plant region (TPP) during 2014. At PA and PV locations, samples were taken during multiple years. This is the first use of Kohonen self-organizing map (SOM) in combination with honeybees as bioindicators to determine spatio-temporal variations and origin of Pb pollution. It was observed that during the years Pb concentrations were in decline. Anthropogenic sources are most dominant in BG and TPP, in PA there are mixed sources of natural and anthropogenic origin and in PV Pb is of natural origin. It can be concluded that honeybees in combination with SOM can be used to differentiate between slight changes in spatio-temporal variations of Pb, as well as for source appointment.

Chemometrics in biomonitoring: Distribution and correlation of trace elements in tree leaves.

The concentrations of 15 elements were measured in the leaf samples of Aesculus hippocastanum, Tilia spp., Betula pendula and Acer platanoides collected in May and September of 2014 from four different locations in Belgrade, Serbia. The objective was to assess the chemical characterization of leaf surface and in-wax fractions, as well as the leaf tissue element content, by analyzing untreated, washed with water and washed with chloroform leaf samples, respectively. The combined approach of self-organizing networks (SON) and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) aided by Geometrical Analysis for Interactive Aid (GAIA) was used in the interpretation of multiple element loads on/in the tree leaves. The morphological characteristics of the leaf surfaces and the elemental composition of particulate matter (PM) deposited on tree leaves were studied by using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) detector. The results showed that the amounts of retained and accumulated element concentrations depend on several parameters, such as chemical properties of the element and morphological properties of the leaves. Among the studied species, Tilia spp. was found to be the most effective in the accumulation of elements in leaf tissue (70% of the total element concentration), while A. hippocastanum had the lowest accumulation (54%). After water and chloroform washing, the highest percentages of removal were observed for Al, V, Cr, Cu, Zn, As, Cd and Sb (>40%). The PROMETHEE/SON ranking/classifying results were in accordance with the results obtained from the GAIA clustering techniques. The combination of the techniques enabled extraction of additional information from datasets. Therefore, the use of both the ranking and clustering methods could be a useful tool to be applied in biomonitoring studies of trace elements.

The novel approach to the biomonitor survey using one- and two-dimensional Kohonen networks.

To compare the applicability of the leaves of horse chestnut (Aesculus hippocastanum) and linden (Tilia spp.) as biomonitors of trace element concentrations, a coupled approach of one- and two-dimensional Kohonen networks was applied for the first time. The self-organizing networks (SONs) and the self-organizing maps (SOMs) were applied on the database obtained for the element accumulation (Cr, Fe, Ni, Cu, Zn, Pb, V, As, Cd) and the SOM for the Pb isotopes in the leaves for a multiyear period (2002-2006). A. hippocastanum seems to be a more appropriate biomonitor since it showed more consistent results in the analysis of trace elements and Pb isotopes. The SOM proved to be a suitable and sensitive tool for assessing differences in trace element concentrations and for the Pb isotopic composition in leaves of different species. In addition, the SON provided more clear data on seasonal and temporal accumulation of trace elements in the leaves and could be recommended complementary to the SOM analysis of trace elements in biomonitoring studies.