Sedimentary conditions based on the vertical distribution of radionuclides in small dystrophic lakes: a case study of Toporowe Stawy Lakes (Tatra Mountains, Poland).

The aim of this work was to prove the use of radionuclides deposited in sediment core taken from an overgrowing dystrophic lakes surrounded by marsh-peat vegetation to estimate sedimentary conditions. Sediment core samples were taken from the Toporowe Stawy Lakes (Nizni (TSN) and Wyzni (TSW); Tatra Mountains). The sampling was done using a Limnos corer. After the physical sample preparations, gamma measurements were performed. Radiochemical analysis was applied with the aim of determining 210Pb radioactivity by means of 210Po. The mean values for TSN lake are as follows: 137Cs ~ 123 Bq∙kg-1, 40 K ~ 389 Bq∙kg-1, 228Th ~ 55 Bq∙kg-1, 226Ra ~ 86 Bq∙kg-1, 241Am ~ 5 Bq∙kg-1, and 210Pbuns ~ 180 Bq∙kg-1. For TSW lake, the radioactivity levels of 226Ra and 241Am are comparable to the TSN. The mean values of 137Cs, 40 K, and 228Th are almost twice as high as in TSN. The level of 210Pb in uppermost layer of TSN is higher than in TSW. Sediments were dated by use of 210Pb method, and the rate of sedimentation of each layer was also estimated. Basic chemometric tools were used to confirm the way of deposition of radionuclide, find the correlations between variables, and compare analyzed lakes. It was concluded that the presented type of lakes are a valuable source of information and the vertical distribution of radionuclide can be used to interpret the source of material supply and factors that influence the sedimentation process in recent 150-200 years.

Lake biota response to human impact and local climate during the last 200 years: A multi-proxy study of a subalpine lake (Tatra Mountains, W Carpathians).

Element content, loss-on-ignition, chironomid analysis and (210)Pb dating were applied on a sediment core from a subalpine Tatra lake (Popradské pleso) to reveal the response of aquatic biota to eutrophication induced by human activities in the lake catchment. The lead dating indicates that the 0-8 cm section of the core represents the past ca 200 years, ending at ~1814 AD. Comparing the key changes of the proxies with human activities that are historically well documented, four phases of the recent lake development were distinguished: (1) a pre-tourism phase, (2) a phase of increasing touristic activity and early cottage development, (3) a phase of eutrophication, and (4) a phase of post-eutrophication. Neither touristic activity, nor early cottage development around the lake (1st and 2nd phases) had considerable influence on the chironomid assemblage structure or organic content of the lake. The most significant change both in chironomid assemblage structure and loss-on-ignition occurred during the 3rd phase, when a big tourist hotel was built close by the lake and started contaminating it via direct wastewater input. However, the structure of the chironomid assemblage has not changed significantly over time and the dominating taxa remained the same during the whole period. Parallel with the nutrient signal of the paleo assemblage, a secondary signal has been identified as the ratio of rheophilic taxa on total abundance that did not correlate with the sediment's organic content, and is most likely driven by local climatic oscillations. Changes of most of metal elements concentrations reflected rather bigger scale changes of industrial activities than local scale human disturbances. Our results indicate that hydromorphological properties can moderate the impact of organic pollution on the lake biota.

Concentrations of 137Cs and 40K radionuclides and some heavy metals in soil samples from the eastern part of the Main Ridge of the Flysch Carpathians.

The aim of the study is to present the results of determination of radioactivity of artificial 137Cs and natural 40K and certain heavy metals in soil samples collected from the eastern part of the Main Ridge of Carpathians, including the Beskid Niski Mts and the Bieszczady Mts. The evaluation of level of radionuclides was based on the bulk density analysis of the soil. A valuable finding of the study was a good linear correlation between the level of 137Cs concentration and bulk density of the soil as well as an inverse correlation between radioactivity of natural 40K and tested soil density. This might indicate though a high competitiveness of these elements between each other. Moreover, a good correlation between the concentrations of artificial element 137Cs and Pb has been also observed in soil samples collected from the Beskid Niski Mts. In most cases, the level of artificial 137Cs was lower comparing to an average 137Cs concentration established for soils in Poland.

Radionuclides and heavy metal concentrations as complementary tools for studying the impact of industrialization on the environment.

The aim of the study was to determine whether using chemical and radiochemical analysis of lake sediments can highlight changes in the climate. Also it was studied whether human impact on the environment can be observed and to what extent such changes are in agreement with historical data. Samples of 16 cm thick sediment cores from the Smreczynski Staw Lake were collected and divided into 1 cm thick sub-samples. The samples were air dried and homogenized. The quantitative analysis of Fe, Mn, Zn, Cr, Cu, Ni, Cd, and Pb in the digested sediment samples was made by using atomic absorption spectrometry. Simultaneously, the radioactivity of 137Cs using gamma spectrometry and 210Pbuns using alpha spectrometry, were measured for sediment layer dating. Results showed that iron concentration was in the range 0.3-over 1 % (w/w), and zinc 0.01-0.05 % (w/w). Lesser concentrations were found for copper 18.37-43.6 ppm, manganese 37.5-50.7 ppm, lead 146.1-432 ppm, chromium 12.3-37.4 ppm, nickel 3.1-10.8 ppm and cadmium 0.9-34.6 ppm. Changes in 137Cs radioactivity was in the range of 89 ± 11 to 865 ± 62 (Bq kg-1). Sediments composition can accurately reflect (in terms of time and to what extent) air pollution and natural geo-chemical processes in the environment. However, the choice of the analysed object is crucial in this respect. The Smreczynski Staw Lake, due to its location in the mountains and hydrological situation, proved to be very useful for providing undisturbed analytical samples.