Content of Ni and Cr in water and in algae from selected Black Sea bays in the region of Sevastopol

Trace metals play an important role in functioning of marine and ocean ecosystems. The particular importance of these elements in ecosystems of salt water basins results from their low concentrations in waters of these basins. The content of trace elements in ocean waters is from a few to several dozen times lower than in fresh waters. Such conditions caused that sea organisms developed, by means of evolution, the ability to intensive absorption of trace elements from water in order to meet the physiological demand for them. However, such abilities can cause excessive bioaccumulation of trace elements in ecosystems with elevated their supply, caused by human pressure or enrichment of the water environment from natural sources. The aim of this paper was to assess the nickel and chromium content in water and in algae from selected Black Sea bays near Sevastopol. The samples of water and algae were collected in August 2012 from eight bays in the region of Sevastopol (Galubaja, Kozacha, Kamyshova, Kruhla, Striletska, Pishchana, Pivdenna, the Sevastopolska Bay) as well as one sample from the open sea near Fiolent. Cystoseira barbata and Ulva rigida algae were collected from the same places. The collected water samples were conserved in situ and after being brought to the laboratory their contents of nickel and chromium were determined. The collected algae were rinsed in distilled water, dried, and then homogenized and mineralized. Content of the studied elements was determined in mineralisates by AAS method with electrothermal atomization. It was found that both elements concentrations in water from individual bays were 2–3 times different. The nickel content ranged between 1.74 and 4.14 gNi dm, and the chromium content was between 1.56 and 5.97 gCr dm. Water from the Striletska Bay contained the highest amount of the studied elements. The nickel content in the studied algae ranged between 1.967 and 12.87 mg kg d.m., and the chromium content between 0.342 and 7.650 mg kg d.m. A higher accumulation of these elements was found in Cystoseira barbata than in Ulva rigida. Algae collected in the Sevastopolska Bay contained the highest amount of nickel, and algae from the Pivdenna Bay contained the highest amount of chromium. The content of the studied DOI: 10.2428/ecea.2015.22(4)34 ECOL CHEM ENG A. 2015;22(4):433-446 1 Department of Agricultural and Environmental Chemistry, University of Agriculture in Krakow, al. A. Mickiewicza 21, 31–120 Kraków, Poland, phone: +48 12 662 43 47, fax: +48 12 662 43 41, email: niemiecm@o2.pl, rrkielia@cyf-kr.edu.pl, komorowska.monika@interia.pl * Corresponding author: rrkielia@cyf-kr.edu.pl elements in biomass of the algae was not correlated with their concentration in water. On the other hand, a significant correlation between the nickel content in the algae of both species was found. Values of nickel bioaccumulation coefficients in the studied ecosystems were close to values recorded in environments with high human pressure, whereas in the case of chromium they were very low, much lower than values given in available literature. It was a result of a very high concentration of this element in water, and its moderate content in the algae. Generally, a higher content of the studied elements, both in water and in the algae, was found in all the bays than in samples collected in the open sea. The highest threat of the studied metals was found in the Sevastopolska and Pivdenna Bays.