Browse

51 - 60 of 2,231 items :

Clear All
Earthworms as useful bioindicator of soils contamination around Košice city, Slovakia

Abstract

This study was conducted to investigate heavy metals bioaccumulation in industrialized soils in surrounding of Košice city (Slovakia), using earthworms. In the present research, we used ecotoxicity tests with Dendrobaena veneta (7 and 28-day bioassays) to infer about potential toxic risks to the agricultural (A) and permanent grass vegetation (PGV) of soils around the plant U. S. Steel Košice. The total Fe, Cu, Zn, Pb, Cd, Cr and As contents and eco-toxicological tests of industrialized soils from the Košice area were performed for 12 sampling sites in years 2016 – 2017. An influence of the sampling sites distance from the largest steel producer plant on the total concentrations of heavy metals was determined for Fe, Cd, Cr and As. It was found that earthworms (Dendrobaena veneta) in some cases caused a decrease of metals concentration in contaminated soils, the largest metal concentration differences were recorded in the samples PGV (4) U. S. Steel-plant-main gate. The results of the bioaccumulation factors of heavy metals in D. veneta (BAFs/7-28 d) are < 1 for the studied metals order in the sequence: Cr < Fe < Pb < Cu < As and > 1 for Zn > Cd.

Open access
Economic Analysis: Trickling Filter/Activated Sludge or Nitrifying Trickling Filter/Activated Sludge?

Abstract

The performance and economic simulation and modeling are crucial for accurate and rapid designing, construction, and forecasting future economic needs of municipal wastewater treatment plants (MWWTPs). In this study, combined nitrifying trickling filter/activated sludge (NTF/AS) process was suggested for the modernization of a MWWTP and the performance and economics of MWWTPs based on the combined TF/AS process and combined NTF/AS process were analyzed and compared. In real, the performance, total project construction, total operation labor, total maintenance labor, total material, total chemical, total energy, and total amortization costs of these proposed MWWTPs were calculated and compared. Under the used design criteria and operational conditions in this study, the project construction cost of the MWWTP based on TF/AS was 15.25 % higher than that of the MWWTP based on NTF/AS. Also, MWWTP based on NTF/AS was cost effective and the material and amortization costs for both plants were higher in comparison with the operation, maintenance, energy, and chemical costs. It is necessary to note that this study is a computer simulation for a case and drawing general conclusions only on the basis of this simulation may be insufficient.

Open access
Economic Aspects of Manure Management and Practices for Sustainable Agriculture in Turkey

Abstract

Turkish livestock sector plays very important role in the Turkish GDP and the use of manure affects the environment but the farming sector want the farmers to employ the use of more integrated manure practice. The study assessed the economic impacts of integrated manure and chemical fertilizer used and the manure management practices sustainable for Turkish agriculture. Turkey is dependent on foreign countries not only for energy but for chemical fertilizers raw materials. High price of chemical fertilizers is one of the negative impact, manure substitution will lead to stable macro-economy, and environmental friendly economy and agricultural productivity will also impacts. To achieve these impacts, some manure practices suitable for sustainable rural development in Turkey was assessed.

Open access
Effect of fly ash-lime treatment on the acute toxicity of greywater towards Daphnia magna

Abstract

Acute toxicity of raw and treated greywater towards Daphnia magna was assessed in this study. Treatment was performed with exposure of greywater to the fly-lime mixture After 48 h of exposure, 100 % mortality of D. magna was recorded when testing the following volumetric fractions of the raw greywater streams in the tested liquid medium (%; v/v): 10 % for kitchen greywater, 5 – 10 % for bathroom greywater and 1.25 – 10 % for laundry greywater. After greywater treatment with the fly-ash-lime mixture with pH adjustment to 7.0, 80 % of neonates of D. magna survived after exposure to treated laundry greywater in all dilutions at 48 h. At the same time, 100 % of neonates survived exposure to treated bathroom and kitchen greywater at all volumetric fractions. Therefore greywater had acute toxicity to D. magna, i.e. greywater treatment was required before its discharge or reuse. Values of the Pearson’s correlation coefficient between the chemical components of the raw greywater and treated greywater and the survival of D. magna indicated a lack of statistically significant correlation at 5 % level of significance (p-value > 0.05 in all cases), i.e. the survival of D. magna was independent of the concentration of chemical constituents in greywater samples tested. Further studies will have to be conducted on the chronic toxicity of the greywater effluent after treatment with the fly-lime mixture. Experiments from this study will have to be re-run for the fully scaled-up version of the fly-lime mixture-based greywater treatment systems.

Open access
Effects of radiopharmaceuticals on articular cartilage’s mechanical properties

Abstract

As radiation science and technology advances, nuclear medicine applications are increasing worldwide which necessitate the understanding of biological implications of such practices. Ionizing radiation has been shown to cause degraded matrix and reduced proteoglycan synthesis in cartilage, and the late consequences of which may include degenerative arthritis or arthropathy. Although degenerative effects of the ionizing radiation on cartilage tissue have been demonstrated, the effects on the mechanical properties of articular cartilage are largely unknown. The radiopharmaceuticals, technetium-99m and technetium-99m sestamibi, were utilized on bovine articular cartilage to investigate these effects. We used two different mechanical tests to determine the mechanical properties of articular cartilage. Dynamic and static mechanical tests were applied to calculate compressive modulus for articular cartilage. We observed clearly higher control modulus values than that of experimental groups which account for lesser stiffness in the exposed cartilage. In conclusion, compressive moduli of bovine articular cartilage were found to decrease after radiopharmaceutical exposure, after both instantaneous and equilibrium mechanical experiments.

Open access
Environmentally Friendly Fuel Usage: Economic Margin of Feasibility

Abstract

In the world there are two main problems concerning energy and ecology. Despite the crude oil price fluctuation, it has tended to increase. Moreover fossil fuel burning emits hazard compounds, including greenhouse gas. To solve them alternative fuels for vehicle have to be used. In due to properties, their usage impacts on the engine efficiency. The alternative fuel usage needs additional investment costs on the vehicle engines adaptation and fuel supply infrastructure. So, decisions must be based on mathematical apparatus. Three submodels were used in the suggested mathematical model: energy and economic indicator for fuels; energy and economic indicator for vehicles; criteria for investment projects. As a criterion of investment projects the profitability index has been grounded. The mathematical model and the algorithm for determining the feasibility of the alternative fuel utilization have been developed. The proposed algorithm includes the following stages: calculation of the fuel energy cost; calculation of the criteria for vehicles; determining the maximum value of investments; making decisions. Biofuels and gaseous fuels for some countries have been studied. The economic attractiveness of the alternative transport fuels has been presented. According to mathematical modeling, gaseous fuels are more economically attractive compared with liquid biofuels. Among gaseous fuels, LPG has a higher economic efficiency. The economic margin of alternative fuel application feasibility has been determined.

Open access
Escherichia coli as Possible Agents of Spread of Multidrug Resistance in Port Harcourt, Rivers State.

Abstract

Multidrug resistance (MDR) continues to be a growing global issue. The problem of MDR is fuelled in part by the spread of the genes encoding resistance horizontally which is linked particularly to conjugation involving plasmids. Studies have demonstrated the presence of plasmids in drug resistant isolates, few have shown a link between these plasmids and drug resistance via plasmid curing especially in our locale. This study set out to explore this link in Escherichia coli isolates from Port Harcourt, Nigeria. Plasmid curing was done on a selection of clinical and non-clinical bacteria using acridine orange and antibiotic susceptibility testing carried out on both cured and uncured variants. Data generated was analysed to ascertain the multiple antibiotic resistance (MAR) index and MDR of each isolate. Data was then compared to ascertain effects of plasmid curing on antibiotic resistance of the isolates. Results revealed a decrease in resistance to 7 of 8 antibiotics following plasmid curing. The highest change was noted in ceftazidime (40%), followed by ofloxacin (26.7%). Plasmid curing caused a shift in MAR index values of isolates from higher to lower indices. At MAR index values of ≤0.25 occurrence increased from 5% to 36.7% while at MAR index values ≥0.75, occurrence reduced from 29.9% to 10.0%. A reduction in the degree of MDR was noted (from 55% to 36.7%). Strikingly, the reduction in MDR level of non-clinical isolates was 30% as opposed to 3.4% in the clinical isolates. This study shows a link between plasmids and antibiotic resistance. For the non-clinical isolates, the high-level link between MDR and plasmid carriage could indicate a higher use of antimicrobials in non-clinical rather than clinical settings. Additionally, it could be an indicator for a higher risk of the transfer of MDR determinants from non-clinical sources to human populations in our locale.

Open access
Extreme Variabilities of Rainfall and Runoff Regime within Vulnerable Hydrographic River Basins. Case Study: Elan River Basin, 2016 (Romania)

Abstract

The present paper analyzes the extreme variabilities of rainfall and runoff regime within vulnerable hydrographic river basins, focused on a case study: Elan river basin, year 2016. This year, due to excess rainfall, the Elan River basin was affected by torrential rainfall, warned against by orange and red code hydrological forecasts. For this reason, this study makes an analysis of the spatial and temporal variability of the surface runoff also considering the main flood events occurring in this river basin. The impact of liquid precipitation on the surface runoff will be highlighted by a statistical analysis of the relationship between monthly average flows and the sum of monthly precipitation in the river basin. The monthly flows series from the Murgeni and Poșta Elan hydrometric stations were capitalized through appropriate statistical analyses. Maximum flows were reported to the thresholds values corresponding to the Defense Levels.

Open access
The first evidence of Acidithiobacillus albertensis in weathered ore samples from active gold mine Hodruša-Hámre (Slovakia)

Abstract

Sulphur-oxidising autotrophic bacterial communities in deep biosphere from weathered ore samples from active gold mine Hodruša-Hámre, Slovakia were analysed using cultivation approach followed by DNA extraction, PCR amplification and 16S rRNA gene analyses. Indirect measurement of pH changes in cultivation media evidenced the presence of acidophilic bacteria with active production of acids. The decrease of pH was observed at the beginning of isolation and later pH in range of 1.5 – 2 was maintained in both, sulphuric acid and thiosulphate, media. The presence of homogenous population of gram-negative rods was proved by Gram staining. Molecular analyses have revealed that the population of sulphur-oxidising bacteria in gold mine is dominated by a single species of Aciditiobacillus genus, identified as A. albertensis, suggesting the low level of autotrophic bacteria diversity in deep deposits. For the first time this species was isolated from weathered rocks of a gold mine subsurface environment.

Open access
Floristic Biodiversity of Weed Communities in Arable Lands of Istria Peninsula (From 2005 to 2017)

Abstract

This paper analyses the floristic biodiversity of weed communities in the arable lands of the Istrian peninsula during a twelve year period (2005–2017). A total of 50 fields were surveyed for each sampling time using the seven-degree Braun-Blanquet cover abundance scale in the following agricultural categories: a) permanent crops (vineyards/olive groves), b) alfalfa fields, c) cereals, d) row crops and e) ruderal areas. The taxonomic identification was performed during the full development of vegetation, for cereals in June and July, and for the rest – in August and September. A total of 175 weed species were determined during both study periods with Asteraceae and Poaceae families as the most abundant. Altogether, therophytes were dominant in both surveys, followed by hemycryptophytes and geophytes. Variations in species composition were visible in both study periods (2005 and 2017) as well as in the selected habitat types. Exclusive species were found in addition to those that were common for both surveys. Changes in species composition between 2005 and 2017 referred to the difference in row spacing in earlier period, and ruderal vs. agricultural habitats in the recent survey. The differences in phenological traits between the past and present surveys were greatest for germination season in permanent crops and row crops, flowering start for permanent crops, flowering period for ruderal area and weed height for permanent crops. Significant differences between the past and present survey for other plant traits did not occur.

Open access