engleski

Accumulation of Macro- and Trace Elements in Amphipod Synurella ambulans from Hyporheic Zone of the Sava River, Croatia

The hyporheic zone (HZ) belongs to the local and regional interstitial groundwater ecosystems and to the most threatened aquatic environments. Bioaccumulation monitoring allows us to gain insight into the bioavailability of the pollutants in the environment and their biomagnification in the food chain. The aim of this research was to evaluate the accumulation of macro- and trace elements in stygophilous amphipod Synurella ambulans which inhabits HZ of the Sava River in Croatia. Concentrations of 12 elements (As, Ba, Cs, Rb, Se, Sr, Tl, V, Ca, K, Mg, and Na) in interstitial water and in amphipods were measured by high resolution inductively coupled plasma mass spectrometry. The study was conducted in the middle section of the Sava River at two study sites: 1) Medsave – located about 3 km upstream from the wastewater outlet of the city of Zaprešić and 2) Jarun – located about 13 km downstream from this wastewater outlet and within the Zagreb City area, during the 4 seasons: winter 2018, spring, summer, and autumn 2019. At both sampling sites the increasing order of metals in S. ambulans was as follows: Tl < Cs < V < As < Se < Rb < Ba < Sr < Mg < Na < K < Ca. In interstitial water, metals at both sampling sites had similar increasing order as in S. ambulans and the concentration ranges were the following: < 0.1 µg L-1 (Cs, Tl), < 1 µg L-1 (As, Se, V), 1 - 5 µg L-1 (Rb), > 10 µg L-1 (Ba) and > 100 µg L-1 (Sr). In general, higher metal accumulation was observed for Rb, Se, Tl, K, and Na in S. ambulans specimens from the Medsave site and for As, Ba, Cs, V, Ca, and Mg from the Jarun site in all studied seasons. Comparison between chemically similar alkali and alkaline earth macro- and trace elements in S. ambulans showed that bioaccumulation factors (BAFs) increase in the following order: Mg < Na < Ba ≈ Sr < Ca < K < Rb < Cs. In this case, the tendency to accumulate in S. ambulans increased with the relative atomic mass of the element. BAFs were generally higher at Medsave, with average values ranging from 165 to 19, 534 L kg-1, and Cs with the highest BAF. It is considered that Cs is concentrated by crustaceans probably because of its chemical similarity to K, and it may derive from the radioactive wastes in fresh water [1, 2]. Cesium has the potential to biomagnify with increasing trophic levels in aquatic food webs [3]. Also, it has been shown that Cs had an impact on the neuromuscular system by increasing the amplitude of excitatory postsynaptic potentials [4]. Biomonitoring of HZ is crucial for protection and conservation of these generally little- considered groundwater connected ecosystems. These are the first results on concentrations of presented elements in S. ambulans and as such are essential for assessing point source of water pollution and global evaluation of groundwater ecological quality.

groundwater ecosystems ; biomonitoring ; crustaceans ; alkali elements ; alkaline earth elements ; bioaccumulation factors

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