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Radiation induced degradation of Congo red dye: a mechanistic study

Abstract

Synthetic dyes are persistent pollutants with poor biodegradability. The present study is about the degradation of direct Congo red dye in aqueous media using the Co-60 gamma radiation source. The experimental conditions such as gamma-ray absorbed doses, amount of oxidant (H2O2) and pH conditions were evaluated. The λmax of dye solution was noted as 498 nm, and then, decrease in absorbance and reduction in chemical oxygen demand (COD) were examined. The complete colour removal of dye was observed at 5 kGy, while a significant COD removal was observed at 15 kGy gamma-ray absorbed dose in conjunction with oxidant for 50 mg/L concentration. It was found that pH has no influence on degradation efficiency. A possible degradation pathway was proposed. The radiolytic end products were monitored by Fourier transform infrared (FTIR) and gas chromatography coupled with mass spectrometry (GC-MS) to explore the degradation mechanism. It was imperative to study the oxidative degradation pathway to provide directions for potential applicability of advanced oxidation process (AOP) in industrial wastewater treatment.

Open access
Regional Climate Change and Surface Waters

Abstract

The actual period marred by the global warming requires expanding our knowledge on the regional particularities of climate changes manifestations as consequences of global climatic changes. It was stated that within the limits of Republic of Moldova’s territory the pace of warming is much more accelerated than the global one. These consequences, in their turn, had led to the increase in degree of evaporation of surface waters, which had conditioned the doubling of still water’s pollution in the region (Lake Beleu). We consider that the obtained results could contribute to the adequate management of water resources in the new climatic conditions.

Open access
Relationship between Environmental Features and Bird Assemblages in the Wetlands of Eastern Romania

Abstract

The avian habitats in Eastern Europe are poorly managed in last decades. It is of highly noteworthy influence importance to obtain more information regarding the link between birds’ presence and environmental features in wetlands to improve this poorly managed system. In our study we investigated the effects of the various habitat, landscape fragmentation and weather variables on the bird assemblages in Eastern Romania, described by diversity, species richness and abundance of non-passerine birds in wetlands. Poisson regression modelling revealed wetland area, wetland heterogeneity, proportion of open-water, density of patches and habitats, landscape shape and temperature conditions have a noteworthy influence on the bird assemblages (p<0,05). Our results suggest that the link between environmental features and birds’ assemblage, in our study areas could be dependent on the presence of the emergent vegetation (shelter / reproduction zones), the balance between open-water area (feeding / nesting zones) and also other variables, as the temperature, the presence of the human living facilities and/or intensive fish nurseries in the neighboring zones. Waterbird distribution and abundance in eastern part of Romania are driven by similar factors to other part of the world and this study could be one of the first published on the topic in a region where It is a lack of information on waterbirds ecology. Such studies would bring valuable information about the ecologic factors influencing the lives of the birds, in the areas that were not stueid before, resulting in better conservation efforts and wetland protection, in estern part of Europe.

Open access
Retention Efficiency of Vegetative Filter Strips for Nitrogen in Danjiangkou Reservoir Area, Central China

Abstract

To investigate the retention efficiency and mechanism of nitrogen of Vegetative filter strips (VFSs) in the Danjiangkou Reservoir area, simulated runoff discharging experiments were carried out in a new-established Bermuda VFS. The results showed that the Bermuda VFS reduced 73.1-86.1 % of surface runoff through infiltration. The outflow rate of runoff increased first and then became stable with time. The concentration reduction rates (CRRs) and load reduction rates (LRRs) of NH3-N increased initially and then decreased with the increase of inflow concentration. The average CRRs and LRRs of NH3-N in three treatments ranged 66.1-90.3 % and 90.0-96.7 %, respectively. The concentration reduction of NH3-N was primarily achieved by soil adsorption. The optimal inflow concentration of NH3-N for the optimum CRR was between 0.65 and 3.52 mg/dm3. The CRRs and LRRs of NO3-N fluctuated between 6.8-14.0 % and 72.0-77.9 % in three treatments. The concentration reduction of NO3-N was primarily achieved by plant uptake and soil microbe assimilation. The optimal inflow concentration of NO3-N for optimum CRR exceeded 6.78 mg/dm3. The CRRs and LRRs of TN increased with the increase of inflow concentrations. The average CRRs in the low, moderate and high treatments reached 9.7, 14.8 and 27.4 %, respectively, and the average LRRs reached 72.1, 74.3 and 81.2 %, respectively. The optimal inflow concentration of TN for optimum CRR exceeded 10.21 mg/dm3. The study showed that Bermuda grass can retain nitrogen in runoff efficiently and should be promoted around the Danjiangkou reservoir.

Open access
Salt and the Development of Human Settlements with Balnear and Climateric Potential within the Romanian Intra-Carpathian Space

Abstract

Deposit salt in Romania has extremely important reserves, considered even inexhaustible at the current exploitation level. The biggest salt resources are found in the intra-Carpathian arch, represented by Transylvania and Maramures. Most sources of salt outcrops are disseminated on the edge of the Transylvania Depression, in the diapir folds formed following salt migration. The salt mines – Turda, Praid, Ocna Mures, Ocna Dej, Ocna Sibiu, Cojocna, Ocna Sugatag – represented an important source of incomes, reason for which important human settlements formed around them. All these localities have turned nowadays into balneal and climacteric resorts that fully use the beneficial effect of the atmosphere within galleries (Praid, Turda). The most important incomes from tourism are represented by the galleries of the mines of Turda (one of the 10 wonders of the modern world) and Praid. The balneal and climacteric resorts also developed around the salt lakes installed in the areas of collapsed mines: Sovata, Ocna Sibiu, Ocna Dej, Cojocna. The most well known human settlements and the most important balneal and climacteric resorts, implicitly, are disseminated on the external branch of the Transylvania Depression (Sovata, Praid, Ocna Mures, Baile Figa, Cojocna thermae, Ocna Dej, Ocna Sibiu) and of the Maramures Depression (Ocna Sugata, Costiui, Vad). The oldest mining exploitation is situated at Figa (county of Bistrita-Nasaud) was founded around the year AD 3000. From this point of view, it is one of the oldest mining exploitations on Earth. The existence of the world-important archaeological site can invigorate the development of the surrounding localities, but mostly of the city of Beclean.

Open access
Sewage Sludge Biochar Effects on Phosphorus Mobility in Soil and Accumulation in Plant

Abstract

In the course of analysing sewage sludge biochar (BC) as a material containing phosphorus loads, we determined the following: effect of thermal conversion of three different sewage sludge biochars on the content and availability of P in biochars (BC-1, BC-2 BC-3), effect of their application on selected forms of P in soil and on the accumulation of this component in Poa pratensis L. biomass. Regardless of the type of BC, the contents of P-H2O and P-CaCl2 were lower than the contents determined in unconverted sewage sludge. A significant increase in the content of P-CaCl2 compared to the control was noted in the soil of treatments where 1 and 2 % additions of BC-2 and BC-3 were applied. Soil pH (r = 0.826; p ≤ 0.05) and the content of Ca-exchangeable (r = 0.712; p ≤ 0.05) had the strongest effect on the content of P-CaCl2 in soil; however, no significant relationship was found between the amount of P-introduced with BC, the contents of Al-ox., Fe-ox. and the content of P-CaCl2. Significant (p ≤ 0.05) increase in the phosphorus content in plant biomass was noted in all treatments compared to the control. Regardless of the type of biochar applied, the highest amount of P-uptake was determined in treatments where the greatest addition of BC (2 %) was introduced into the soil. A significant relationship between P-uptake and the amount of P-introduced with BC into the soil (r = 0.726; p ≤ 0.05) was demonstrated.

Open access
Silver and Gold Ions Recovery from Batch Systems Using Spirulina platensis Biomass

Abstract

In order to assess ability of Spirulina platensis to recover silver and gold ions from the environment the bioaccumulation of silver and gold ions and their effect on growth, proteins and carbohydrates content of Spirulina platensis biomass was studied. Silver nitrate (AgNO3) in concentration range 0.01-1 mg/dm3 and tetrachloroaurate Na[AuCl4] in concentration range 18.5-370 mg/dm3 were added as component of the Spirulina platensis cultivation medium. In case of silver two cultivation media were studied: standard and Cl-free. The process of silver and gold uptake was traced using neutron activation analysis. Presence of silver ions in standard cultivation medium reduced biomass productivity by 66 %, while in Cl-free biomass productivity was reduced by 11.8 % only. The reduction of proteins content by 30 % in Cl-free medium and by 19 % in standard medium was also observed. The experiments showed that in case of gold ions loading, the biomass productivity and protein content were reduced only at high Na[AuCl4] concentration in the medium. The behaviour of carbohydrates content change was similar under silver and gold loadings: decrease at low metal concentration followed by increase at high metal concentrations. Scanning electron microscopy allowed observation of spherical metal nanoparticles, which were formed extracellularly during silver and gold bioaccumulation. Spirulina platensis can be used for recovery of precious metals as well as metal nanoparticles production.

Open access
Simulated nuclear contamination scenario, solid cancer risk assessment, and support to decision

Abstract

The detonation of an (hypothetical) improvised nuclear device (IND) can generate atmospheric release of radioactive material in the form of particles and dust that ultimately contaminate the soil. In this study, the detonation of an IND in an urban area was simulated, and its effects on humans were determined. The risk of solid cancer development due to radiation was calculated by taking into account prompt radiation and whole-body exposure of individuals near the detonation site up to 10 km. The excess relative risk (ERR) of developing solid cancer was evaluated by using the mathematical relationships from the Radiation Effects Research Foundation (RERF) studies and those from the HotSpot code. The methodology consists of using output data obtained from simulations performed with the HotSpot health physics code plugging in such numbers into a specific given equation used by RERF to evaluate the resulting impact. Such a preliminary procedure is expected to facilitate the decision-making process significantly.

Open access
Soil Fertility Assessment of an High Natural Value Eligible Area in South-Eastern Transylvania

Abstract

As low-input environmentally friendly agricultural practices are currently associated with the delivery of a wide range of public goods and socioeconomic benefits, the strategy of European Union in mitigating climate change effects, protecting environment and ensuring public health has, among others, focused around preserving the High Natural Value (HNV) areas. About a quarter of the land in Romania is potentially covered by HNV farming and eligible for associated support payments, mostly along the chain of the Carpathian Mountains. Since soil systematic data on HNV area are scarce, recent research developments currently undertake to build up a first national HNV soil data base.

Soil fertility state in a HNV payment eligible area of south-eastern Transylvania was studied in seven in-depth dug profiles and seven additional shallow dug profiles. Soil samples were taken by genetic horizons as well as agrochemical samples from the upper soil layers (0-20 cm). Physical, chemical, and microbiological analyses revealed that the studied soils have a medium clayey loamy texture, good fertility and are subject to an adequate HNV management in the area, as the analytical values mostly range in favorable intervals for plant growth and nutrition. Thus, soil reaction is moderately acid up to slightly alkaline in the presence of carbonates, the soil organic matter, generally well mineralized, reaches fair levels and the high and very high cation exchange capacity ensure good conditions for plants growth and nutrition whilst nitrogen and potassium supply is adequate. Phosphorus is the only element in short supply – a situation often encountered in Romania unfertilized soils. Soil bulk density and total porosity are also favorable for root growth and spreading and plant nutrition. Microorganisms’ activity is diverse and is also adequate for plant nutrition.

Open access
Some New Heterocyclisations Based on N-(2,2-dichloro-1-isothiocyanatoethyl)benzamide Derivatives

Abstract

Based on the readily available N-(2,2-dichloro-1-(2-(4-methylbenzoyl)-hydrazine-1-carbothioamido)ethyl)benzamide, the corresponding N-(2,2-dichloro-1-((5-(p-tolyl)-1,3,4-oxadiazol-2-yl)amino)ethyl)benzamide and 5-(p-tolyl)-1,3,4-thiadiazol-2-amine were obtained. The products were received in acceptable yields and were isolated from the reaction mixture without any particular difficulty. The structure of the compounds obtained was confirmed by 1H, 13C NMR spectroscopy and mass spectrometry data.

Open access