Influence of landfill site Baštijunski brig on the chemical composition of uppermost sediments of Vrana lake in Ravni kotari area

Fajković, Hana (2014) Influence of landfill site Baštijunski brig on the chemical composition of uppermost sediments of Vrana lake in Ravni kotari area. Doctoral thesis, Faculty of Science > Department of Geology.

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Abstract

Field examination and laboratory analysis were performed to establish whether Baštijunski brig landfill has a negative influence on Vransko Lake, situated only 1,5 km away, and whether pollution can be detected in the lake.Vransko Lake is Croatia’s largest natural lake, and is part of a nature park and ornithological reserve, which indicates its high biodiversity. Therefore it is necessary to understand the environmental processes and complex sediment/water interface. Lakes and lake sediments present a good surrounding and natural system for tracking environmental changes over time, such as climatic and see level changes, the distribution of radionuclides, and levels of pollutants. Lake sediments are considered to be a good „sinkhole“ and are often the final recipients of anthropogenic and natural pollutants through adsorption onto the organic or clay fraction in sediments. Such deposition doesn’t have to be permanent and redistribution of pollutants can occur due to changed environmental conditions. Lake sediments and soil from the landfill were sampled and measured for several aspect; the content of carbonate components was measured by gas volumetric with a Scheibler calcimeter; granulometric composition of sediments by laser granulometer; activity of radionuclides 40K, 137Cs and 232Th by gamma-spectrometry method; mineralogical analysis by X-ray diffraction; and amount of dioxins in deferent media (i.e. air, sediment and soil). Also, sequential extraction chemical analysis and total chemical analysis by aqua regia i.e. pseudototal analysis were performed on samples. Data were statistically analysed by correlation and cluster analysis. Distribution maps of analysed elements were obtained by the kriging method. Ecological risk index for aquatic pollution is used to identify risk index for deferent parts of a lake. The lake is situated parallel to the coast line, in a Dinaric direction of stretching, i.e. NW–SE. Apart from establishing whether there is evident influence from the landfill in lake sediments, the goal was to define if differences throughout the lake due to its elongated shape, and different environmental conditions on its marginal parts (NW and SE) can be determined. Fifty-nine sediment cores were sampled from a 30 m2 area with gravitational corer. Sampling of air and soil from Baštijunski brig were also done. The majority of the groundwater flow and the lake watershed are from the direction of Ravni kotari, situated NW Summary 140 of the Vransko Lake, and it is presumed to be the main source of terrigenic material to the lake. On the other hand, the SE part of the lake is connected with Adriatic Sea with the Prosika channel. Lake sediment and air samples from Vransko Lake were analyzed for the presence of Dibenzo-p-dioxins (PCDDs) and Dibenzofurans (PCDFs) compounds. Waste incineration is one of the formation mechanisms for these compounds. A landfill site is located near the lake, and landfill fires occasionally occur accidentally. The first two centimetres of lake sediment were sampled in the summer of 2008 and 2010 to determine whether dry deposition of PCDDs and PCDFs - formed during landfill fire - ended up in the lake. Outdoor air was collected during a 2007 landfill fire for a 5 day period, with a total sample volume of 485,623 m3. The air was pumped through an air sampling pump with integrated adsorption unit of polymer resin (XAD), which was later analysed. All analyses were determined by high resolution gas chromatography - high resolution mass spectrometry (HRGC/HRMS). The presence of dioxins was determined in all analysed media, with the accent that in air it was detected during the time in which the fire occurred on the landfill. The highest amount of dioxin was detected in the soil sampled from the landfill area. All detected values were within the permitted limits set out in the legislation. It should be kept in mind that transformation of some congeners can occur which can lead to higher total toxic equivalent, without any newly source of pollutant. Prior to performing radiometric analyses, samples were dried at 50°C to the constant weight, ground in an agate mortar, and homogenized. Plastic counting containers of 125 cm3 volume were filled to the top and firmly sealed. Radiometric analyses of all samples were performed by gamma-spectrometry technique using a HPGe semiconductor detector with a multichannel analyzer (Canberra Industries). Primordial natural radionuclides 40K and 232Th, present in all rocks, sediments and soils were used as indicator of terrestrial/detritic material. Radionuclide 137Cs was used for estimation of sedimentation rate. In the NW part of the lake sedimentation rates of 10.0, 4.1 and 5.0 mm/a were estimated for the 1954–1964, 1964–1986, and the 1986–2010 periods, respectively. At the SE part, sedimentation rates for the respective periods were as follows: 8.0, 2.3 and 2.5 mm/a. Average sedimentation rates were 6.4 mm/a for the NW part of the lake and 4.2 mm/a for the SE part. Further, negative correlations between CaCO3 mass fractions and radionuclides mass activities were determined, and positive correlations between the radionuclides mass activities. Such correlations can help with interpretation of source material origin. Summary 141 Sediment grain-size distribution was determined by Laser Diffraction Particle Size Analyzer (LS 13 320). Internationally accepted classification of sediments according to Folk was used to classify the samples. Although the silt to sand ratio in different samples was very variable, all samples were classified as sandy silt with a mean grain size of 20–56 μm. The same sediment types indicate uniform sedimentation conditions in different parts of the lake. Considering the type of the sediment, the deposition environments can be regarded as the lowto medium-energy environments. Also, samples are very poorly sorted which indicates that the sediment sizes are mixed and that the variance is large. Dried until the constant weight, ground, and homogenized, 82 samples from 7 sediment cores were subjected to determination of the CaCO3 mass fraction. Analyses were performed according to the Austrian standard methods ÖNORM L1084 using a Scheibler calcimeter. The amount of carbonate components is high in all analysed samples - not less than 71%. Two trends can be defined, in a dependence of a sediment core location. First, one where carbonate components show uniformity among analysed cores and the second one where there is a high negative correlation between radionuclides 40 K and 232Th with the carbonate components. Minor decrees of carbonate components is registered in the NW part of a lake , correlates with a higher sedimentation rate defined by the anthropogenic radionuclide 137Cs. Speciation of heavy metals by modified BCR sequential extraction procedure with the addition of a first step of sequential extraction procedure by Tessier and analysis of residual by aqua regia were used to determine the amounts of analysed elements in different fractions, i.e. which element will be extracted from sediment/soil in a different environmental conditions. All sediment and soil samples were analysed by inductively coupled plasmaatomic emission spectrometry. Precision and accuracy were determined by duplicate analysis and certified reference materials (BCR 701, GBW 07410 and SRM 1646), as well as recovery of methods for each certified reference material. The pseudototal content obtained by direct dissolution of the samples using aqua regia were compared with the sum of contents obtained from each fraction of the sequential extraction procedure and residue analysis, and recovery values were calculated. Recovery was within 100±10%, indicating results of a good quality. Results of sequential extraction chemical analysis, especially the one from step 1T+BCR1, are a valuable tool for interpretation of the mobile fraction of the elements, considered bioavailable, that present threat to biota in a case of a contaminant concentration magnification. An increase of mobile fraction for elements Cr, Co, Mn, Al and Fe obtained Summary 143 from data and distribution maps throughout the lake, for each step of sequential extraction chemical analysis, was established. Detected concentrations are within maximum permitted concentrations established by Regulation. Mentioned analysis and distribution maps pointed out a zone which wasn’t in a scope of investigation, and for which is recorded higher amount of mobile fraction of elements Cd, Cu and Zn in accordance with the other part of the lake. This zone coincides with the Živača estavele(“vrulja”), connected with the 7,5 km distant Jasenovac sinkhole and 13,8 distant Perušić sinkhole. Clarification of such distribution requires additional analysis and terrain prospection. Such unexpected results signify the advantage of simultaneous use of geochemical data and distribution maps attained by a kriging method presenting statistical distribution of analysed paramether. Prior to the phase analysis, sediment was dried to the constant weight, ground, and homogenized. X-ray diffraction technique was used to determine the qualitative mineral phase composition of the sediments. Phase determinations of the bulk samples were performed using a Philips X’pert powder diffractometer with CuKα radiation from the tube operating at 40 kV and 45 mA. An X-ray diffraction data set was collected from 4°to 63° 2Θ. Carbonate components dominate, composed of low and high Mg calcite and aragonite with some quartz, pyrite, muscovite and kaolinit. The ecological risk index was defined by the model proposed by Hakanson. With the model of ecological risk index for aquatic pollution, a difference appears between a central part of a lake and its shore. High potential ecological risk was defined for a NW part of a lake, and high „toxic – response „ factor of a Cd contribute mainly to this. Settings of high potential ecological risk signify that the presence of landfill has a negative influence on the lake sediment.

Item Type: Thesis (Doctoral thesis)
Keywords: odlagalište otpada, Baštijunski brig, jezerski sedimenti, Vransko jezero, Ravni kotari
Supervisor: Prohić, Esad
Date: 2014
Number of Pages: 207
Subjects: NATURAL SCIENCES > Geology
Divisions: Faculty of Science > Department of Geology
Depositing User: Sonja Borak
Date Deposited: 27 Jan 2014 12:15
Last Modified: 28 Jan 2014 12:25
URI: http://digre.pmf.unizg.hr/id/eprint/262

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