OCHRONA ŚRODOWISKA I ZASOBÓW NATURALNYCH VOL. 26 NO 4(66): 40-47 ENVIRONMENTAL PROTECTION AND NATURAL RESOURCES 2015 DOI 10.1515/OSZN-2015-0022 Izabela Bojakowska ⃰, Olimpia Kozłowska ⃰ , Bartosz Stec ⃰ Trace elements in lake sediments of the Brda river catchment area Pierwiastki śladowe w osadach jezior zlewni Brdy ⃰ Prof. dr hab. Izabela Bojakowska, dr Olimpia Kozłowska, mgr Bartosz Stec – Polish Geological Institute – National Research Institute, Rakowiecka 4 St., 00-975 Warsaw, Poland, e-mail: [email protected], [email protected] , [email protected]. Keywords: lake sediments, trace elements, pollution Słowa kluczowe: osady jeziorne, pierwiastki śladowe, zanieczyszczenie Abstract Streszczenie Total of 54 samples (of sediments taken from the surface of 5-cm W zlewni rzeki Brdy zbadano osady 54 jezior, które zostały layer of profundal zone of lakes in the catchment of the river pobrane ze strefy profundalnej z powierzchniowej 5cm warstwy. Brda) were tested in presented research. The collected samples W pobranych próbkach oznaczono zawartość Ag, As, Ba, Cd, were analysed for the concentrations of Ag, As, Ba, Cd, Co, Cr, Co, Cr, Cu, Ni, Pb, Sn, Sr, V i Zn oraz Al, Ca, Fe, Mg, Mn, P i S Cu, Ni, Pb, Sn, Sr, V and Zn, and Al, Ca, Fe, Mg, Mn, P and S, metodą ICP-OES, po roztworzeniu próbek w wodzie królewskiej using inductively coupled plasma atomic emission spectroscopy oraz oznaczono zawartość Hg metodą TMA i węgla organicznego (ICP-AES), after sample digestion in aqua regia. The Hg - metodą kulometryczną z próbki stałej. Większość zbadanych concentration was determined from solid samples using atomic próbek charakteryzowała się niską zawartością pierwiastków absorption spectroscopy (TMA). The organic carbon content was śladowych. Osady zawierały średnio 0,9 mg/kg Cd,0,107 mg/kg determined using the coulometric method. Sediments of most of Hg, 8 mg/kg Ni, 46 mg/kg Pb, 8 mg/kg As, 78 mg/kg Ba, 12 mg/kg lakes examined in the Brda catchment area are characterised by Cr, 94 mg/kg Zn, 3 mg/kg Co, 12 mg/kg Cu, 1,3 mg/kg Mo, 105 mg/ low concentrations of trace elements. Sediments contained an kg Sr i 16 mg/kg V. Stwierdzono, że obecność podwyższonych average of 0.9 mg/kg of Cd, 0.107 mg/kg of Hg, 8 mg/kg of Ni, zawartości Cr, Cu, Ni i V w osadach jezior uwarunkowana jest 46 mg/kg of Pb, 8 mg/kg of As, 78 mg/kg of Ba, 12 mg/kg of Cr, czynnikiem geogenicznym - wietrzeniem utworów pochodzenia 94 mg/kg of Zn, 3 mg/kg of Co, 12 mg/kg of Cu, 1.3 mg/kg of Mo, polodowcowego, zaś obecność podwyższonych zawartości Pb, 105 mg/kg of Sr and 16 mg/kg of V. The presence of elevated Zn, Hg i Cd spowodowana jest czynnikiem antropogenicznym. W concentrations of chromium, copper, nickel and vanadium is przeważającej ilości zbadanych osadów stężenia As, Cd, Cr, Cu, controlled by a geogenic factor – weathering of glacial deposits Hg, Ni były niskie i niestwarzające zagrożenia dla organizmów containing fragments of igneous and metamorphic rocks which wodnych. W blisko połowie próbek zawartość ołowiu była are the source of heavy metals. The presence of elevated podwyższona do poziomu, przy którym może być obserwowany contents of Pb, Zn, Hg and Cd is caused by anthropogenic factor. negatywny wpływ tego pierwiastka na organizmy wodne, a w Most of the lake sediments show low concentrations of As, Cd, Cr, przypadku cynku w około 25% próbek. Cu, Hg and Ni, which do not pose a threat to aquatic organisms. The concentrations of lead in almost half of the samples are elevated to a level at which a negative effect of this element can be observed. In the case of zinc, the proportion of such samples is about 25%. © IOŚ-PIB 1. INTRODUCTION Under natural conditions, lake sediments are formed through which precipitate out of the water. Chemical composition of these the accumulation of allochthonous material derived from erosion sediments, including the concentration of trace elements, is and weathering of rocks occurring in the catchment area of a controlled by the properties of rocks occurring in the catchment water body (including the accumulation of quartz and feldspar area of the lake and by climatic conditions [Bojakowska, Gliwicz grains, carbonate minerals and clay minerals) and through the 2009; Fei Zhang et al 2013]. deposition of biogenic autochthonous material (which forms In the recently accumulated sediments, elevated concentrations at the site of sedimentation) and inorganic autochthonous of a number of elements, including chromium, zinc, cadmium, material. Inorganic autochthonous material is represented by copper, lead and mercury, are often observed compared to the chemical compounds, such as silica, calcium carbonate, iron and concentrations of these components in the sediments that were manganese hydroxides, iron sulphides, and calcium phosphate, formed during pre-industrial times [Aleksander-Kwaterczak, 40 Izabela Bojakowska, Olimpia Kozłowska, Bartosz Stec Prosowicz 2007; Cooke et al. 2007; Pulford et al. 2009; Tylmann protected landscape areas, nature reserves and special areas of 2004; Pompeani et al. 2013]. This is due to the human economic habitat conservation. The surface water environment in this area activity carried out in lake’s catchment area, deposition of is polluted mainly because of agriculture and animal husbandry pollutants from the atmosphere and rainwater and melt water and by pollutant emissions from fuel burning for household and runoff [Rocher et al. 2004; Wildi et al. 2004; Cui et al. 2010; municipal needs and in transportation. Taylor, Owens 2009]. Lake sediments are characterised by their ability to accumulate inorganic contaminants and countless 3. RESEARCH SCOPE AND METHODS types of organic pollutants, for example, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and The study has used the research results of the National organochlorine pesticides. The presence of high concentrations Environmental Monitoring running in order to monitor the of potentially harmful metals in the sediments, such as Zn, Cu, concentrations of potentially harmful elements and persistent Cr, Cd, Pb, Ni and Hg, as well as of persistent organic pollutants, organic pollutants in recent sediments of rivers and lakes and adversely affects the quality of surface water environment. to record their changes over time. During the implementation of Contaminated sediments are a threat to organisms inhabiting the tasks of the State Environmental Monitoring, sediments of them and participating in the biogeochemical transformations 54 lakes were surveyed in the Brda river catchment area in the that play a crucial role in maintaining good water quality and period 1995–2014. Sediment samples were taken from a 5-cm- distribution of organic matter. Contamination of modern water thick sediment layer of the profundal zone of the lakes, using a sediments is currently one of the most important environmental Van Veen sampler. problems because of the potentially harmful impact on biological The samples collected were analysed for the concentrations of resources and often indirectly on human health. Contaminants Ag, As, Ba, Cd, Co, Cr, Cu, Ni, Pb, Sn, Sr, V and Zn, and Al, Ca, found in sediments can accumulate in the trophic chain to Fe, Mg, Mn, P and S, using inductively coupled plasma optical a level that is toxic to aquatic organisms, especially predators emission spectrometry (ICP-OES), after sample digestion in [Radomski et al. 2006: Fu et al 2013]. They can also pose a risk to aqua regia. The concentration of Hg was determined from solid humans and animals consuming fish or shellfish inhabiting areas samples using thermal decomposition amalgamation atomic where such sediments occur [Vink 2009; Sorour, Harbey 2012; absorption spectrometry (TDA AAS). The organic carbon content Xiao et al., 2013]. was determined using the coulometric method. In order to assess the research quality, reference lake sediment material WQB- 2. STUDY AREA 3 was also analysed (standard – Trace Metals in Sediments, developed by the Aquatic Ecosystem Protection Branch, National The Brda river is a 238-km long left tributary of the Vistula Water Research Institute, Canada, Burlington, ON). river. Its catchment area is 4627 km2. The river flows from Lake Smołowe in the Bytów Lakeland northeast of the town of 4. RESULTS AND DISCUSSION Miastko and enters the Vistula river at its 771 km in Bydgoszcz. According to the physiographic division, the Brda river catchment The studies have shown that the average concentrations of trace area belongs to the South-Baltic Lakeland [Kondracki 2002], elements in lake sediments of the Brda river catchment area are occupying almost the whole Charzykowy Plain, the entire Brda higher than the average concentrations of these elements in water Valley, south-western part of the Tuchola Forest, eastern part sediments of Poland [Lis, Pasieczna 1995]. As regards the most of the Krajeńskie Lakeland, the eastern Świecko Upland and a harmful elements to aqueous organisms (Cd, Hg, Ni and Pb), the small part of the Toruń Valley. The Brda river catchment area sediments contain the following amounts on an average: 0.9 mg/ is characterised by a late-glacial relief with hills and numerous kg of Cd, 0.107 mg/kg of Hg, 8 mg/kg of Ni and 46 mg/kg of Pb. lakes. Quaternary sediments that occur at the surface, mainly Considering the group of trace elements that are important for glacial tills and glaciofluvial sands, are typified by low contents of the environment quality, but pose a lesser threat to the biota, the potentially harmful trace elements. sediments contain the following amounts on an average: 8 mg/kg The Brda river basin is an agricultural and forest area. Agricultural of As, 78 mg/kg of Ba, 12 mg/kg of Cr, 94 mg/kg of Zn, 3 mg/kg land accounts for 48.6% of the catchment area, forests and semi- of Co, 12 mg/kg of Cu, 1.3 mg/kg of Mo, 105 mg/kg of Sr and natural ecosystems – 45.8%, anthropogenic areas – 2.4%, and 16 mg/kg of V.