Bedload sediment transport model for revealing the multi-year trend of polychlorinated biphenyl contamination in the river sediment (Kupa, Croatia).

This article investigated the multi-year polychlorinated biphenyl (PCB) burden of the sediment collected along the Kupa River flow in Croatia using the bedload sediment transport model. Kupa, as the natural border between Croatia and Slovenia, belongs to the water system Krupa (Slovenia) → Lahinja (Slovenia) → Kupa (Croatia) → Sava → Danube → Black Sea. From 1962 to 1985, the total quantity of waste calculated for pure PCBs, released by a capacitor manufacturer into the environment within various locations of the Krupa River in Slovenia, was 70 tons. Krupa River (Slovenia) has become one of the most PCB-polluted rivers in Europe, and consequently, PCBs have been detected in the Kupa River (Croatia). Model application revealed that contamination of the Kupa River (Croatia) started significantly earlier than 1983, when a high concentration of PCB was detected for the first time in the Krupa River (Slovenia), with probably significantly higher sediment concentrations at the upstream boundary of the Kupa. A slow concentration changes and PCB accumulation in the sediment should be expected downstream compared to the upstream boundary, governed mainly by high flow events. The PCBs in sediments from 2020/2021 are markedly different after the Lahinja confluence with Kupa (0.2-0.6 µg kg-1 vs. 1.4-34.3 µg kg-1). Measurements of PCBs in Kupa sediment suggest that the intake of PCB has not yet been completely stopped, which should be confirmed by detailed monitoring in the future. The contamination situation observed in the Kupa River represents an excellent example of the persistency of PCBs in the environment.

Salivary cortisone as potential predictor of occupational exposure to noise and related stress.

Salivary cortisone strongly correlates with serum cortisol, and since it is less invasive to measure salivary cortisone than serum cortisol and easier than to measure cortisol in saliva, as its concentrations are much lower, we wanted to compare salivary cortisone and cortisol levels as markers of noise-induced stress reaction. The study included 104 participants aged 19-30 years, 50 of whom were exposed to occupational noise ≥85 dB(A) and 54 non-exposed, control students. All participants took samples of their saliva with Salivette® Cortisol synthetic swabs on three consecutive working days first thing in the morning. Salivary cortisone and cortisol levels were determined with high-performance liquid chromatography. In addition, they completed a 10-item Perceived Stress Scale (PSS-10) questionnaire, and occupationally noise-exposed participants also completed the Health and Safety Executive (HSE) questionnaire on occupational psychosocial risks. The exposed participants had significantly higher cortisone (P<0.001) and cortisol (P<0.001) levels than controls, and the correlation between cortisone and cortisol levels in the exposed participants was strong (ϱ =0.692, P<0.001), which suggests that salivary cortisone can replace cortisol measurements in saliva as a more reliable method than salivary cortisol and less invasive than serum cortisol. However, the level of perceived stress scored on PSS-10 in the exposed participants did not differ significantly from stress reported by controls, but correlated negatively with cortisone levels, which is contrary to our expectations and raises questions as to why.

Seasonal distribution of multiclass pesticide residues in the surface waters of northwest Croatia.

As part of our OPENTOX project, we evaluated the incidence and mass concentrations of multiclass pesticide residues in 23 river/stream water samples collected in urban and agricultural areas of northwest Croatia at various points of the pesticide application season in 2015. The study included 16 compounds of five herbicide classes and seven compounds of three insecticide classes. Pesticide residues were accumulated from water by solid-phase extraction and analysed using high performance liquid chromatography with UV-diode array detection and/or gas chromatography-mass spectrometry. Herbicide residues were more common than the insecticide ones, and, as expected, they peaked in the middle of the application season. Metolachlor showed the highest concentrations and was found in 91 % of all samples, followed by terbuthylazine, found in 70 % of the samples. The highest total mass concentration of detected pesticides was measured in the water samples of the Krapina (3992 ng/L) and Sutla (3455 ng/L) collected in rural areas with intensive agriculture. Our findings strongly speak in favour of continued monitoring of surface waters and possibly extending the list of priority water pollutants.

Distribution of Organochlorine Pesticide and Polychlorinated Biphenyl Residues in Lake Sediment Cores from the Plitvice Lakes National Park (Croatia).

The occurrence and distribution of 11 organochlorine pesticides (OCPs) and their degradation products as well as of 17 polychlorinated biphenyl congeners (PCBs) were investigated for the first time in sediments of three (Lake Prosce, Lake Kozjak, Lake Kaluderovac) out of 16 cascading karst lakes within the protected area of the Plitvice Lakes National Park in central Croatia. The 15-cm-long sediment cores were divided for analysis into three 5-cm-long segments. The abundance and levels of sediment-associated OCPs and PCBs were evaluated with respect to sampling location and sediment depth, presumed age of deposition, and organic carbon content. The burden of sediments with OCPs and PCBs decreased downstream with the highest mass fractions measured in the uppermost Lake Prosce (total OCPs 2.72-5.86 µg kg-1 d.m., total PCBs 0.37-1.78 µg kg-1 d.m.) and the lowest in Lake Kaluderovac (total OCPs 0.30-0.58 µg kg-1 d.m., total PCBs 0.07-0.12 µg kg-1 d.m.). The predominant organochlorine pollutants were DDT-type compounds (total DDX, w = 0.30-5.72 µg kg-1 d.m.) with p,p'-DDE and p,p'-DDD accounting for up to 100% and 50%, respectively, of the total DDX. The findings indicated an old input of p,p'-DDT that largely converted to its degradation products. The OCP and PCB mass fractions in the Plitvice lake sediments were at trace levels characteristic for preserved pristine natural environments with no or limited anthropogenic impact wherein long-range atmospheric transport is considered as their main source.

Soil burden by persistent organochlorine compounds in the vicinity of a coal-fired power plant in Croatia: a comparison study with an urban-industrialized area.

The impact of a coal-fired Plomin Power Plant (PPP) in Croatia on PCB soil burden was examined by comparing the occurrence, levels, and profile of PCBs in soil from the PPP with the values determined in urban-industrialized soil (Varazdin, Croatia). Soil burden by organochlorine pesticides (OCPs) were also investigated at both locations. Topsoil samples were collected at five distances (100-800 m) along a downwind pollution gradient from the PPP and across the city. The total content of PCBs in 100-m soil was nearly 20-fold the levels found in 800-m soil, which pointed to the PPP as a local source of soil contamination. The PPP soils were dominated by indicator PCB congeners, particularly hexa-homologs. A different profile and mass fraction range of PCBs in soils from PPP and Varazdin area indicated the different sources of contamination. Levels of total PCBs in PPP soils (0.25-19.07 µg kg-1) were higher than PCB levels determined in soils from Varazdin (0.29-5.52 µg kg-1), partially as a result of higher OC content in PPP soils. PPP soil burden by PCBs corresponded to a lower end of PCB level ranges reported for cities with high population and heavy industry. OCPs were detected at significantly higher levels in Varazdin soils than in PPP soils, with the highest contribution of the DDT-like compounds (DDX) detected in soils affected by river deposits. The p,p'-DDE/p,p'-DDT ratio in Varazdin soils indicated a fresh atmospheric input of p,p'-DDT. The PPP soil analysis detected a presence of only p,p'-DDE and HCB at levels corresponding to their global environmental presence.

Dissipation dynamics of terbuthylazine in soil during the maize growing season.

Ever since terbuthylazine (TBA) replaced atrazine in herbicide crop treatment, its much greater persistence has raised considerable environmental concern. The aim of our field experiment was to establish the dissipation dynamics of TBA and its degradation product desethylterbuthylazine (DET) in soil over five months of maize growth. We applied TBA as part of pre-emergent treatment in the regular and double-the-regular amounts. Soil samples were collected periodically at the following depths: 0-10 cm, 10-20 cm, 20-30 cm, and 30-50 cm. For TBA and DET soil residue analysis we used microwave-assisted extraction with methanol, followed by HPLC-UV/DAD. Regardless of the application rate, more than 80 % of the applied TBA dissipated from the first 50 cm of soil in the two months after herbicide application and 120 mm of rainfall. Three months later (at maize harvest), less than 4 % of total TBA remained in the soil, mostly in the top 20 cm rich with organic carbon on which TBA is likelier to adsorb. The loss of TBA from soil coincided with the rise in DET, especially the top soil layers, during the periods of low rainfall and highest soil temperatures. This points to biodegradation as the main route of TBA dissipation in humic soils. The applied amount had no significant effect on TBA dissipation in the top (humic) layers, but in the layers with less than 1 % of organic carbon, it was higher when the doublethe- regular dose was applied.

The impact of multiple anthropogenic contaminants on the terrestrial environment of the Plitvice Lakes National Park, Croatia.

The anthropogenic impact on the terrestrial environment of the Plitvice Lakes National Park (PLNP) was investigated through the analysis of three groups of major contaminants (persistent organochlorine pollutants including 15 organochlorine pesticides (OCPs) and 17 polychlorinated biphenyls (PCBs), trace elements/heavy metals (6 major and 23 trace constituents), and anthropogenic radionuclides ((90)Sr, (134)Cs, and (137)Cs)) in three terrestrial compartments (soil, air, and bioindicators of air contamination) during 2011-2013. The correlation coefficients of element mass fractions with soil properties indicated that total Fe and Al minerals, soil organic matter (OM), and organic carbon (OC) content affected the mass fractions of most trace elements in the topsoils. The annual and spatial distributions of heavy metals in total deposited matter (TDM) indicated that the metals came from natural sources and long-range transfer of particulate matter. The PCB and OCP levels found in soil and conifer needles corresponded to global environmental pollution levels by persistent organic pollutants and represented the lower end of the mass fraction ranges reported in the relevant literature. Analyses of anthropogenic radionuclides in bioindicators (conifer needles, lichens, and mosses) showed low but measurable activity concentrations of (134)Cs (for the first time after the Chernobyl accident), which indicated origin from the March 2011 Fukushima Nuclear Power Plant accident. Our overall results indicated that human activity inside or near the PLNP had no significant impact either on contaminant spread by air or on their content in topsoils.

Catabolism of terbuthylazine by mixed bacterial culture originating from s-triazine-contaminated soil.

The s-triazine herbicide terbuthylazine (TERB) has been used as the main substitute of atrazine in many EU countries for more than 10 years. However, the ecological consequences of this substitution are still not fully understood. Since the fate of triazine herbicides is primarily dependent on microbial degradation, in this paper, we investigated the ability of a mixed bacterial culture, M3-T, originating from s-triazine-contaminated soil, to degrade TERB in liquid culture and soil microcosms. The M3-T culture grown in mineral medium with TERB as the N source and citrate as the C source degraded 50 mg L(-1) of TERB within 3 days of incubation. The culture was capable of degrading TERB as the sole C and N source, though at slower degradation kinetics. A thorough LC-MS analysis of the biodegradation media showed the formation of hydroxyterbuthylazine (TERB-OH) and N-t-butylammelide (TBA) as major metabolites, and desethylterbuthylazine (DET), hydroxydesethylterbuthylazine (DET-OH) and cyanuric acid (CA) as minor metabolites in the TERB degradation pathway. TBA was identified as a bottleneck in the catabolic pathway leading to its transient accumulation in culture media. The supplementation of glucose as the exogenous C source had no effect on TBA degradation, whereas citrate inhibited its disappearance. The addition of M3-T to sterile soil artificially contaminated with TERB at 3 mg kg(-1) of soil resulted in an accelerated TERB degradation with t 1/2 value being about 40 times shorter than that achieved by the native microbial community. Catabolic versatility of M3-T culture makes it a promising seed culture for accelerating biotransformation processes in s-triazine-contaminated environment.

Effect of organic and mineral soil fractions on sorption behaviour of chlorophenol and triazine micropollutants.

This article compares the sorption behaviour of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, pentachlorophenol, chlorotriazine atrazine, methylthiotriazine ametryn, methoxytriazine atratone, hydroxyatrazine, and didelakylated atrazine in a topsoil and an aquifer sediment before and after removal of sorbent organic matter and in humic acid. Freundlich isotherm coefficients Kf and 1/n and free energy change (deltaG degrees ) were calculated for all compounds in all sorbents. According to sorbent pH values, chlorophenolate anions and uncharged triazine species dominated in all sorption experiments with topsoil and aquifer sediment. In experiments with humic acid, chlorophenols, atrazine, and didealkylated atrazine existed almost completely as neutral species, whereas protonated species dominated for hydroxyatrazine, atratone, and ametryn. In addition to a hydrophobic partition, sorption of all compounds in native soil and sediment sorbents includes specific, more polar interactions, which greatly depend on sorbate acidity/basicity, specific properties of the sorbent organic matter and of mineral surface, as well as on the system pH. A significantly greater sorption intensity of all compounds in "organic-free" than in the native aquifer sediment confirmed the importance and possible dominance of mineral surface in the sorption process. Sorption intensity of chlorophenol and triazine compounds in humic acid was closely related to compound hydrophobicity. Greater sorption of almost completely protonated hydroxyatrazine than of the more hydropohobic but uncharged atrazine indicated different humic acid reaction sites for two compounds and consequently different sorption mechanisms.