Kinetic studies of lead(II) uptake by the seagrass Zostera muelleri in water by radiotracing,atomic absorption spectrometry and electrochemical techniques

Evidence was found that uptake of lead from seawater in both model and natural systems by the leaves of the seagrass Zostera muelleri does occur for live, dead and scraped leaves at all the lead concentrations tested. Positive uptake of lead was measured using the three analytical techniques of radio-tracer, differential pulse anodic stripping voltammetry and atomic absorption spectrometry; similar uptake profiles were obtained for each technique. Profiles always showed an initial rapid uptake phase followed by a gradual transition to a plateau phase at which an approximate equilibrium between lead attached to seagrass and free ionic lead in seawater was reached. The presence of active lead uptake processes was indicated in experiments which attempted to remove lead from leaves by a chelating agent.     

Boundary-layer parameterizations for applied dispersion modeling over urban areas

Many applied dispersion models require the knowledge of boundary-layer parameters such as sensible heat flux,Q _H , friction velocity,u _*, and turbulent energy components, _w and _v . Formulas are suggested for calculating these parameters over a wide variety of types of ground surfaces, based on simple observations of wind speed near the ground and fractional cloud cover, and specification of constants such as roughness length, albedo, and soil moisture availability. Observations ofu _*,Q _H , _w , and _v during field experiments in St. Louis and Indianapolis are used to test the formulas for urban sites. Relative errors of about ±20% in the predictions are seen to occur whenu _*,Q _H , _w , and _v are large. However, when these quantities are small (e.g.,u _* < 0.2 m/s), the errors in the predictions are as large as the mean value of the quantity itself.In addition, it is concluded from studies of available field data and theories that the magnitude of _w is not well-known at elevations above about 100m during the late afternoon and night. Some simple parameterizations for _w . are suggested that are consistent with the observed steady decrease in ground-level concentration in the afternoon and the sudden increase in concentration that can occur a few hours after sunset due to wind shears associated with a low-level jet, for continuous plumes emitted from moderate to tall stacks.     

Microlaboratory study on magnetic,gravity and high-tension separation of hercynite and pleonaste from low-grade ilmenite concentrates

Some ilmenite concentrates obtained from oleate flotation of ilmenite ores from NE Poland contain less than the required 45% TiO₂ due to the presence of green spinels (hercynite and pleonaste). Such concentrates were further upgraded by different separation techniques. It was established at microlaboratory scale that magnetic, gravity and high-tension separations can provide qualified ilmenite concentrates with TiO₂ recovery in the order of 50 to 80%.     

Long-term changes (1980–2003) in total ozone time series over Northern Hemisphere midlatitudes

Long-term changes in total ozone time series for Arosa, Belsk, Boulder and Sapporo stations are examined. For each station we analyze time series of the following statistical characteristics of the distribution of daily ozone data: seasonal mean, standard deviation, maximum and minimum of total daily ozone values for all seasons. The iterative statistical model is proposed to estimate trends and long-term changes in the statistical distribution of the daily total ozone data. The trends are calculated for the period 1980–2003. We observe lessening of negative trends in the seasonal means as compared to those calculated by WMO for 1980–2000. We discuss a possibility of a change of the distribution shape of ozone daily data using the Kolmogorov-Smirnov test and comparing trend values in the seasonal mean, standard deviation, maximum and minimum time series for the selected stations and seasons. The distribution shift toward lower values without a change in the distribution shape is suggested with the following exceptions: the spreading of the distribution toward lower values for Belsk during winter and no decisive result for Sapporo and Boulder in summer.     

Intensity of in‐lake processes in floodplain lakes within the Bug River zone of fluvial activity

The paper presents a new approach to calculating the erosion and deposition values of floodplain lake basins, the erosion–deposition index (EDI). The EDI is a sum of the basin geometry indices (BGIs), which can be calculated for a separate cross section of the lake. The distribution of processes within the basin was investigated in two selected floodplain lakes with the use of BGIs. Field research was carried out in the Bug River valley from 1 November 2006 to 31 October 2011. The highest erosion was observed in the lakes located close to the parent river. Deposition processes were observed in lakes with high inflow of groundwater. The results showed that EDI values of 48 out of the 71 floodplain lakes ranged from ?0.2 to 0.2. Spatial distribution of erosion and deposition processes within the lake basins resulted from a velocity of water inflowing or flowing through the basin. This was observed especially in contrafluent–confluent lake. Inflow of rivers water via upstream crevasse occurred later than via downstream one, but energy of flowing water was higher, which favoured erosion of this part of the lake basin. Copyright © 2013 John Wiley & Sons, Ltd.     

Stone Age settlement and Holocene shore displacement in the Narva‐Luga Klint Bay area,eastern Gulf of Finland

Based on geological and archaeological proxies from NW Russia and NE Estonia and on GIS‐based modelling, shore displacement during the Stone Age in the Narva‐Luga Klint Bay area in the eastern Gulf of Finland was reconstructed. The reconstructed shore displacement curve displays three regressive phases in the Baltic Sea history, interrupted by the rapid Ancylus Lake and Litorina Sea transgressions c. 10.9–10.2 cal. ka BP and c. 8.5–7.3 cal. ka BP, respectively. During the Ancylus transgression the lake level rose 9 m at an average rate of about 13 mm per year, while during the Litorina transgression the sea level rose 8 m at an average rate of about 7 mm per year. The results show that the highest shoreline of Ancylus Lake at an altitude of 8–17 m a.s.l. was formed c. 10.2 cal. ka BP and that of the Litorina Sea at an altitude of 6–14 m a.s.l., c. 7.3 cal. ka BP. The oldest traces of human activity dated to 8.5–7.9 cal. ka BP are associated with the palaeo‐Narva River in the period of low water level in the Baltic basin at the beginning of the Litorina Sea transgression. The coastal settlement associated with the Litorina Sea lagoon, presently represented by 33 Stone Age sites, developed in the area c. 7.1 cal. ka BP and existed there for more than 2000 years. Transformation from the coastal settlement back to the river settlement indicates a change from a fishing‐and‐hunting economy to farming and animal husbandry c. 4.4 cal. ka BP, coinciding with the time of the overgrowing of the lagoon in the Narva‐Luga Klint Bay area.