Mining waste as a cause of increased bioaccumulation of highly toxic metals in liver and gills of Vardar chub (Squalius vardarensis Karaman, 1928).

Freshwater contamination with mining waste can result with high concentrations of toxic metals in the water and in fish organs. In North-Eastern Macedonia, several rivers (e.g., Zletovska, Kriva) are exposed to acid mine drainage from active Pb/Zn mines. Previous studies confirmed high concentrations of dissolved metals in their water. This study was performed in liver and gills of Vardar chub (Squalius vardarensis Karaman, 1928) from three Macedonian rivers (Bregalnica, Kriva and Zletovska) in spring and autumn 2012. The aim was to establish if increased exposure to certain metals have resulted with their increased bioaccumulation. The concentrations of 19 elements were measured in cytosolic tissue fractions, to obtain information on metabolically available metal species. The following ranges of cytosolic concentrations of highly toxic elements were measured in the Vardar chub liver (in µg/L): Cd, 1.18-184; Cs, 0.25-25.4; Tl, 0.02-5.80; Pb, 0.70-61.1. Their ranges measured in the gills (in µg/L) were the following: Cd, 0.24-59.2; Cs, 0.39-24.4; Tl, 0.01-1.00; Pb, 0.65-87.2. Although the water of the mining impacted Zletovska River was highly contaminated with several essential metals, especially with Mn and Zn, the majority of essential elements (Na, K, Ca, Mg, Co, Cu, Fe, Mn, Mo, and Zn) did not reflect the exposure level. In contrast, seven nonessential elements reflected the level of exposure in the water. Significantly increased hepatic and gill concentrations of Cs, Rb, Sr, and Tl were detected in Vardar chub from the Zletovska River compared to the other two rivers, of Cd and Pb in the Zletovska and Kriva River compared to Bregalnica, and of V in the Bregalnica River compared to Zletovska and Kriva rivers. Observed significant metal bioaccumulation, in particular of highly toxic elements, as a consequence of exposure to water contaminated with mining waste points to necessity of intensified supervision of mining impacted rivers.

Dissolved organic carbon as potential indicator of global change: A long-term investigation in the northern Adriatic.

Dissolved organic carbon (DOC) is an essential component of the biogeochemical marine system, effecting biological and chemical reactions that take place in the sea. DOC represents a dynamic component of the global carbon cycle. This paper reports 25years of measurements of DOC content and distribution at seven stations along the transect Po River delta - Rovinj in the northern Adriatic (NA). The results show strong temporal and spatial variability: (1) The highest average DOC concentrations were observed in 1998 and 2002 (143µmol/L and 137µmol/L, respectively); (2) The minimum average DOC was recorded in 2006 (88µmol/L) and (3) The short-term DOC accumulation (up to 203, average 102µmol/L) for the years 2009 to 2012, was observed during the summer and autumn months followed by unusually low DOC concentrations during the winter and spring. The DOC results from the more recent monitoring at the same stations indicate primarily oligotrophic characteristics of the NA seawater (88µmol/L). The results of DOC variability and distribution in the NA appears to be strongly influenced by complex circulation patterns. This paper provides a "link" between the Ionian circulation and the NA ecosystem as a part of the recently identified Adriatic-Ionian Bimodal Oscillating System (BiOS). A good agreement between the BiOS oscillation and other variables related to the DOC concentration, like the NA A and B winter types, the Po River discharge, salinity, chlorophyll a, occurrence of hypoxic-anoxic conditions, eutrophication and oligotrophication, suggests that DOC might be a good tool and indicator of global change.

Accumulation of metals relevant for agricultural contamination in gills of European chub (Squalius cephalus).

The study of metal bioaccumulation in the gills of European chub (Squalius cephalus) was conducted in September 2009 at the medium-sized rural river Sutla, characterized by agricultural and municipal type of water contamination. The concentration ranges were established for the first time in the soluble, metabolically available fractions of chub gills for 12 metals, which are environmentally extremely relevant and yet only seldom studied, as follows in a decreasing order: K, 225-895 mg L(-1); Na, 78-366 mg L(-1); Ca, 19-62 mg L(-1); Mg, 13-47 mg L(-1); Rb, 164-1762 µg L(-1); Sr, 24-81 µg L(-1); Ba, 13-67 µg L(-1); Mo, 1.3-16 µg L(-1); Co, 0.7-2.7 µg L(-1); Li, 0.4-2.2 µg L(-1); Cs, 0.2-1.9 µg L(-1); and V, 0.1-1.8 µg L(-1). The concentrations of Fe (1.6-6.4 mg L(-1)) and Mn (16-69 µg L(-1)) were also determined and were in agreement with previous reports. By application of general linear modelling, the influence of different abiotic (metal exposure level) and biotic parameters (fish sex, age, size and condition) on metal bioaccumulation was tested. It was established that bioaccumulation of many metals in fish depended on various physiological conditions, wherein Ba could be singled out as metal exhibiting the strongest association with one of biotic parameters, being significantly higher in smaller fish. However, it was also undoubtedly demonstrated that the concentrations of three metals can be applied as reliable indicators of metal exposure even in the conditions of low or moderate water contamination, such as observed in the Sutla River, and those were nonessential elements Li and Cs and essential element Fe. The results of our study present an important contribution to maintenance of high ecological status of European freshwaters, through enrichment of knowledge on the bioaccumulation of various metals in gills of European chub as frequently applied bioindicator species in monitoring of water pollution.

Adaptation of marine plankton to environmental stress by glycolipid accumulation.

A systematic investigation of non-phosphorus containing glycolipids (GL) was conducted in the northern Adriatic Sea during two years at two stations with different nutrient loads. GL concentration varied both spatially and temporally, with values of 1.1-21.5 µg/L and 0.4-44.7 µg/L in the particulate and the dissolved fraction, respectively. The highest concentrations were measured during summer in surface waters and at the more oligotrophic station, where GL yields (% of total lipids) were often higher than 20% and 50% in the particulate and dissolved fractions, respectively. To obtain more insight into factors governing GL accumulation autotrophic plankton community structure (pico-, nano- and microplankton fractions), chlorophyll a, heterotrophic bacteria and nutrient concentrations were measured together with hydrographic parameters and sunlight intensity. During the investigated period smaller autotrophic plankton cells (pico- and followed by nanoplankton) prevailed in abundance over larger cells (microplankton), which were found in large numbers in freshened surface samples. Several major findings resulted from the study. Firstly, during PO4 limitation, particularly at the oligotrophic station, enhanced glycolipid instead of phospholipid accumulation takes place, representing an effective phosphate-conserving mechanism. Secondly, results suggest that at seawater temperatures >19 °C autotrophic plankton considerably accumulate GL, probably to achieve thermal stability. Thirdly, high sunlight intensities seem to influence increased GL accumulation; GL possibly plays a role in cell mechanisms that prevent/mitigate photooxidation. And finally, substantial accumulation of GL detected in the dissolved fraction could be related to the fact that GL do not contain biologically relevant elements, like phosphorus, which makes them an unattractive substrate for enzyme activity. Therefore, substantial portion of CO2 could be removed from the atmosphere in P-limited regions during summer via its capture by plankton and conversion to GL.

[Organic contaminants in the Jakusevec landfill and their impact on groundwater quality]. / Organska oneciscenja u odlagalistu otpada Jakusevec i njihov utjecaj na podzemne vode.

Landfilling is probably, the most popular disposal method for the management of domestic and industrial waste. Unfortunately, many landfills around the world do not include leachate collection systems and present a considerable risk to the underlying aquifers. There have been numerous reports on groundwater contamination in the vicinity of unprotected landfills, paying particular attention to specific organic contaminants. This problem is especially pronounced in landfills which, in addition to ordinary domestic refuse, contain waste of industrial origin. Jakusevec, the main landfill of the city of Zagreb, belongs to this category. The recently completed remediation programme for Jakusevec included comprehensive investigations with the aim to quantify various organic contaminants in solid waste and establish their possible infiltration into the underlying soils and groundwater. A detailed analyses using chromatographic and mass spectrometric techniques made it possible to identify a number of contaminants. According to their origin, the identified compound classes can be divided into the two main categories: markers of biological waste and its microbial transformation and markers of anthropogenic waste. Our investigations have shown that the composition of organic contaminants changes dramatically during the vertical transport from the solid waste through the unsaturated zone of soil to aquifer sediments, which involves both physicochemical and biotransformation processes. The vertical transport of polar organic contaminants was very efficient and led to a significant contamination of the aquifer in the vicinity of the landfill.

Spatial and temporal variability of carbohydrates in the northern Adriatic--a possible link to mucilage events.

Large-scale mucilage events in the northern Adriatic have become more frequent during the last few decades. Since carbohydrates (CHO) comprise one of the major constituents of the Adriatic mucilage, studying their seasonal and spatial patterns is one of the key prerequisites for the understanding of this phenomenon. This paper reports on the distribution of particulate (PTCHO) and dissolved carbohydrates (DTCHO) in the period from June 1999 to July 2002, with a special emphasis on the summer mucilage events. A particular attention was paid to the relationship between the phytoplankton crop as reflected by photosynthetic pigments and carbohydrate levels in different seasons. The concentration of PTCHO varied in a very wide range (1-72 micromol C/l). Their seasonal distribution revealed that enhanced levels of PTCHO occurred only in the surface layer (0-5 m) and were associated with major phytoplankton blooms. However, the main pool of CHO was in the dissolved fraction, comprising on average 84+/-10% of the total CHO. In contrast to PTCHO, there was no seasonal coincidence between the enhanced phytoplankton biomass and concentrations of DTCHO. In fact, the concentration of DTCHO showed regularly a marked increase during summer, when the phytoplankton biomass remained relatively low. Nevertheless, the concentration of DTCHO in the productive surface layer, influenced by the Po River discharges, was significantly higher than that in the deeper layers. The detailed vertical distribution of carbohydrates indicated that phytoplankton populations in the bottom layer possessed a rather modest potential as a source of CHO. The spatial distribution in the surface layer along the transect Rovinj-Po River mouth revealed only a moderate increase of the total CHO concentration in the more eutrophic western part of the basin. Analysis of pluriannual variability of the total CHO levels showed that probability of a mucilage event in a given year depended on the accumulation of CHO during spring, but, even more, on the prevailing circulation pattern in the basin during the stratification period.