The Influence of the Zebra Mussel (Dreisena Polymorhpa) on Magnesium and Calcium Concentration in Water

In this study we examined changes in magnesium and calcium ion concentrations depending on Zebra Mussel biomass, pH values and temperature. We performed field experiments in years with different weather conditions using twelve 200 litre polycarbonate containers filled with 150 litres of non-filtered water from lowland, eutrophic reservoirs. Three treatments of the experiment were represented by: Phyto control with non-filtered water, Phyto+Dreis A with Zebra Mussel biomass of 500 g/m2, and Phyto+Dreis B with Zebra Mussel biomass of 1.000 g/m2. Magnesium and calcium ions concentrations were analyzed on an ion chromatograph (Dionex-1000). Results indicated a significant reduction in magnesium and calcium ion concentrations by Zebra Mussels (independent of mussel biomass), especially in the year with higher and more stable average temperatures. Mg concentration was significantly negatively correlated with temperature in this year. In both years of study the magnesium and calcium ion concentrations were negatively correlated with pH. Analyses of the Zebra Mussel's impact on magnesium and calcium loss from water, linked with the influence of physical factors (temperature and pH), may be valuable for the management of invaded ecosystems

The influence of temperature on the speed of reduction of TIN oxide with argon- hydrogen mixture

Recently, the usage of hydrogen in the processes of metal extraction has been a very important challenge to metallurgic industry. Replacing conventional reductor, taking into consideration CO2 emission restrictions will enable maintaining and developing this branch of industry. The results of the research on tin oxide SnO reduction using hydrogen given as a mixture Ar – 5 % vol.H2 in temperature range 773 – 873 K. are shown in this article. The tests were conducted using thermogravimetric method. It is demonstrated that with the rise of a temperature in the analyzed range the speed of reaction rises as well and the obtained degree of reduction varies from 40 to 99,5 %. Stabilization the weight change in the tested sample thermogravimetric (TG) was reached after from 25 min for 773 K to 15 min for temperature 873 K

The influence of temperature on the speed of reduction of TIN oxide with argon- hydrogen mixture

Recently, the usage of hydrogen in the processes of metal extraction has been a very important challenge to metallurgic industry. Replacing conventional reductor, taking into consideration CO2 emission restrictions will enable maintaining and developing this branch of industry. The results of the research on tin oxide SnO reduction using hydrogen given as a mixture Ar – 5 % vol.H2 in temperature range 773 – 873 K. are shown in this article. The tests were conducted using thermogravimetric method. It is demonstrated that with the rise of a temperature in the analyzed range the speed of reaction rises as well and the obtained degree of reduction varies from 40 to 99,5 %. Stabilization the weight change in the tested sample thermogravimetric (TG) was reached after from 25 min for 773 K to 15 min for temperature 873 K

Nocturnal Measurements of HONO, NO2 and NO3 by Differential Optical Absorption Spectroscopy in Polluted Marine and Urban Atmospheres

Nitrogen oxides are ubiquitous throughout the lower atmosphere and significantly affect the chemistry of the atmosphere, air quality, and climate. A data-set obtained using differential optical absorption spectroscopy (DOAS) was analyzed in order to quantify the NO3, HONO and NO2 concentrations at Saturna Island, and concentrations of N2O5 were calculated. Nocturnal measurements of NO3, NO2 and HONO were also performed using active-DOAS at York University. A method for calculating the lifetimes of NO3 without assuming a steady-state approximation was determined and non steady-state lifetimes of NO3 were calculated for both studies. The direct (via NO3) and indirect (via N2O5) rate loss constants of NO3 from the combined nocturnal reservoir (NO3+N2O5) were determined as a function of time of night. Measurements of HONO over the polluted open ocean were performed for the first time. Rapidly established steady-states of HONO were observed, persisting throughout the night until sunrise. During the steady-state period (d[HONO]/dt≈0), HONO was independent of the air mass source and NO2, leading to a zero-order HONO formation with respect to NO2, contrary to expectations. Potential reservoirs of HONO were explored and a conceptual model for HONO formation over aqueous surfaces was hypothesized. Subsequently, nocturnal measurements of HONO in the urban area were made at York University for a total of 242 nights. This urban data-set showed two types of HONO behavior. Firstly, a steady-state behavior was clearly observed for a subset of the data-set, similar to that observed in the aqueous environment at Saturna. Secondly, HONO concentrations were observed to highly correlate with NO2 for another subset of the data-set (d([HONO]/[NO2])/dt≈0), showing evidence of first-order behavior as expected for the accepted heterogeneous NO2 hydrolysis mechanism of HONO formation (2NO2 + H2O → HONO + HNO3). Steady-states of HONO were observed during atmospherically unstable nights, while HONO was strongly correlated with NO2 during stable nights. It was discovered that the main parameters distinguishing these two types of behavior were atmospheric stability and NO2 concentration

Comparative study of Navicula hasta Pantocsek and Navicula rakowskae Lange-Bertalot morphology and distribution

Despite numerous reports of Navicula hasta in the literature its distribution still remains unknown. More detailed studies of Navicula hasta and related taxa resulted recently in the separation of several new species. One of these, Navicula rakowskae Lange-Bertalot, was described from a karstic spring in Poland. The holotype of N. hasta, a portion of the type material from the Natural History Museum in Budapest and the material collected from Poland (Krakowsko-Częstochowska Upland) were examined with LM and SEM. Based on the protologue and the material examined the morphological characters of both species are described. Their distribution is briefly discussed on the basis of the material collected and the reliable records in the literature

DEVELOPMENT OF A STATISTICALLY-BASED METHODOLOGY FOR ANALYZING AUTOMATIC SAFETY TREATMENTS AT ISOLATED HIGH-SPEED SIGNALIZED INTERSECTIONS

Crashes at isolated rural intersections, particularly those involving vehicles traveling perpendicularly to each other, are especially dangerous due to the high speeds involved. Consequently, transportation agencies are interested in reducing the occurrence of this crash type. Many engineering treatments exist to improve safety at isolated, high-speed, signalized intersections. Intuitively, it is critical to know which safety treatments are the most effective for a given set of selection criteria at a particular intersection. Without a well-defined decision making methodology, it is difficult to decide which safety countermeasure, or set of countermeasures, is the best option. Additionally, because of the large number of possible intersection configurations, traffic volumes, and vehicle types, it would be impossible to develop a set of guidelines that could be applied to all signalized intersections. Therefore, a methodology was developed in in this paper whereby common countermeasures could be modeled and analyzed prior to being implemented in the field. Due to the dynamic and stochastic nature of the problem, the choice was made to employ microsimulation tools, such as VISSIM, to analyze the studied countermeasures. A calibrated and validated microsimulation model of a signalized intersection was used to model two common safety countermeasures. The methodology was demonstrated on a test site located just outside of Lincoln, Nebraska. The model was calibrated to the distribution of observed speeds collected at the test site. It was concluded that the methodology could be used for the preliminary analysis of safety treatments based on select safety and operational measures of effectiveness