Water quality assessment in a river-sea transition zone. Recent results from distinct aquatic environments of the danube delta biosphere reserve area, Romania

This study aims to compare the water quality in distinct aquatic systems, situated in different representative areas of the Danube Delta Biosphere Reserve, Romania - a unique natural area of national and international importance. These areas are largely populated by a vast diversity of aquatic organisms, including rare species of plants, animals, aquatic birds and fish, many of them being endangered species. Any imbalances in these ecosystems, owing to natural and human-induced changes in the water quality may affect aquatic life. In this sense, water samples were collected from the surface layer of a freshwater environment (i.e., Babina, Rădăcinoasele and Ciorticuț lakes), as well as from mixed environments (i.e., Musura and Sahalin Bays) during August 2018. The following water quality indicators were considered: temperature, pH, dissolved oxygen, nitrite-nitrogen, nitrate-nitrogen, ammonium-nitrogen, orthophosphates, chlorophyll a, total organic carbon, silica, electrical conductivity, total dissolved solids, sulphates, turbidity, total suspended solids, transparency and oxido-reduction potential. These parameters were analysed and discussed in relation to national and international environmental standards. Maps of spatial distribution of some quality parameters were obtained, showing variation as a result of local specific environmental circumstances, which change in time and space. These results suggest that the environmental indicators measured in drought conditions and low water levels showed generally good to moderate water quality status, in spite of many local triggers associated with natural and anthropogenic causes that can alter or impair the quality of the water. After this investigation performed during August 2018, it can be appreciated that the analysed water samples maintain appropriate levels that are suitable for the ecological status of the investigated aquatic systems, and, as expected, the aquatic habitats are ecologically balanced environments. The paper recommends the routine monitoring and periodical testing of the water quality to create and develop a database to reflect the natural variation and human related implications for water quality within these areas, and their short, medium and long-term evolution trends. The present work is important for water quality assessment to detect changes in water quality under human pressures and climate change and to protect and conserve these natural water resources

Water column characteristics in the Clarion Clipperton Fracture Zone, north-eastern tropical Pacific Ocean

Four exploration license areas for manganese nodules (German, Inter Ocean Metal, Belgian, and French) and one Area of Particular Environmental Interest, located within Clarion-Clipperton Fracture Zone (north-eastern tropical Pacific Ocean) were investigated in terms of CTD, nutrients and chlorophyll data during the SONNE 239 cruise carried out in March-April 2015. Chlorophyll measured either in the surface layer (concentrations within 0.05-0.15 mg·m-3) or subsurface chlorophyll maximum layer (concentrations within 0.23-0.45 mg·m-3) showed a quite low primary productivity, strongly influenced by the thermocline position. The shallow thermocline (75-90 m depth) observed in the southern edge of the studied area (≈11°N) led to a shallow and moderate subsurface chlorophyll maximum layer (50-60 m depth and concentrations within 0.4-0.45 mg·m-3). Northwards, at ≈18°N, the thermocline dropped down to 120 m depth, resulting in a deeper (110 m depth) and weaker subsurface chlorophyll maximum (concentration of 0.23 mg·m-3). The oxygen minimum layer, characteristic to the eastern Pacific Ocean, showed a spatial variability in the studied area in terms of the depth of occurrence and thickness. Thus, shallower (80-90 m depth) and thicker (thickness within 1000-1050 m) oxygen minimum zones were observed in the southernmost license areas as compared to the northernmost area (280 m depth and thickness of 750 m)

ON THE GASTALDI – D’URSO FUZZY LINEAR REGRESSION

In the crisp regression models, the differences between observed values and calculates ones are suspected to be caused by random distributed errors, although these are due to observation errors and an unappropriate model structure. So, the fuzzy character of model prevails. The Fuzzy linear regression models (FLRM) are, roughly speaking, of two kinds: Fuzzy linear programming (FLP) based methods and Fuzzy least squares (FLS) methods. The FLP methods have been initiated by H.Tanaka (1982) and developed by H. Ishibuchi et al. The classical FLR model, Y=A0+A1X1+...+AkXk, has a explained Fuzzy triangular variable, Y, Fuzzy triangular coefficients {Aj} and crisp explanatory variables {Xj}: the parameters {Aj} of the model are estimated by minimizing the total indetermination of the model, so each data point lies within the limits of the response variable. In a large number of situations the prediction interval of the FLR model were much less than the interval obtained applying classical the Multiple linear regression model (see V.M. Kandala – 2002, 2003). However, this approach is somehow heuristic; on the other side, the LP model complexity overmuch increases as the number of data points increases. The FLS approach (P. Diamond; Miin-Shen Yang, Hsien-Hsiung Liu – 1988 et al) is an extension of the classical OLS method, using various metrics defined on the space of the fuzzy numbers. A significant number of recent works (McCauley- Bell (1999), J. deA. Sanchez and A. T. Gomez (2003) who used FLS to estimate the term structure of interest rates) deals with models with a fuzzy output, fuzzy coefficients and a crisp input vector. All the fuzzy components are symmetric triangular fuzzy numbers: the main idea of the method is to minimize the total support of the fuzzy coeficients. Sometimes, different restrictions occur. In our paper, we intend to build some examples for the P. d’Urso and T. Gastaldi models, that allow a comparative study on various options. (Pierpaolo d’Urso & Tommaso Gastaldi in: A least square approach to fuzzy linear regression, Comp. Stat. & Data Analysis 2000

Short-cut Method for Assessing Solvents for Gas Cleaning by Reactive Absorption

A new short-cut method (NoVa) for assessing solvents for gas cleaning by reactive absorption is presented. It considers the absorption / desorption cycle using the assumption of infinite number of stages in both columns. For a given feed and removal rate, the method yields an estimate for the specific regeneration energy q as a function of the solvent circulation rate L/G. The sole solvent-dependent input consists of two correlations describing the gas solubility at absorber and desorber conditions and estimates of caloric properties. Furthermore, a simple equation (SolSOFT) for correlating the gas solubility as a function of the gas loading of the solvent is presented. A theoretical analysis of the process reveals general properties of the dependency of q on L/G. The NoVa method is described and tested using amine-based solvents for post combustion carbon capture as examples

The investigation of the water quality and bed-sediment conditions in Cutetchi Lake, Danube Delta, Romania

Danube Delta includes many ecosystems functioning in a dynamic environment that could be considered, each of them, as ”natural laboratories”. In this sense, Cutetchi Lake was chosen for conducting practical investigations (August 2016) and the obtained data will be used to evaluate the impacts associated with natural factors or human-related activities. Water samples were investigated for physical parameters and water-quality constituents. Bed-sediments samples were analyzed for the main lithological components and trace elements to identify the levels, distribution and the potential sources of heavy metals in surficial accumulations. Related environmental standards were used to evaluate the water and sediment quality. Results indicate that, in the surface water the mean concentration of the environmental indicators ranged mainly in line with sampling points and generally agreed with reference standard: transparency (0.94 m), dissolved oxygen (8.98 mg/l), temperature (22.39 oC), conductivity (392.2 µS/cm), total dissolved solids (196.1 mg/l), pH (7.91), Eh (22 mV), turbidity (5.06 NTU), total suspended solids (9.25 mg/l), nitrite-nitrogen (0.01 mg/l), nitrate-nitrogen (0,02 mg/l), soluble orthophosphates (0.17 mg/l), sulphates (25,5 mg/l), silica (6,8 mg/l). The mean sediment parameter values were: moisture (23.13 %), dry sediment content (76.87 %), total organic matter (73.53 %), total carbonates (7.48 %) and minerogenic fraction (18.98 %). In the bed-sediment, the average metal content was: Zn (102.17 mg/kg), Ni (44.77 mg/kg), Cr (73.23 mg/kg), V (75.30 mg/kg), Co (9.38 mg/kg), Pb (24.83 mg/kg), Cu (58.70 mg/kg), Cd (0.82 mg/kg) etc., and individual values only incidentally exceed the maximum recommended level. This work could be a basis for the ongoing evaluation processes of water and sediment quality

One-step in situ synthesis of polyamide microcapsules with inorganic payload and their transformation into responsive thermoplastic composite materials

Well-dispersed loads of finely powdered metals, metal oxides, several carbon allotropes or nanoclays are incorporated into highly porous polyamide 6 microcapsules in controllable amounts via an original one-step in situ fabrication technique. It is based on activated anionic polymerization (AAP) of ε-caprolactam in a hydrocarbon solvent performed in the presence of the respective micro- or nanosized loads. The forming microcapsules with typical diameters of 25-50 µm entrap up to 40 wt% of load. Their melt processing produces hybrid thermoplastic composites. Mechanical, electric conductivity and magnetic response measurements show that transforming of in situ loaded microcapsules into composites by melt processing (MP) is a facile and rapid method to fabricate materials with high mechanical resistance and electro-magnetic characteristics sufficient for many industrial applications. This novel concept requires low polymerization temperatures, no functionalization or compatibilization of the loads and it is easy to scale up at industrial production levels.The authors gratefully acknowledge the financial support of FCT - Portugal (SFRH/BPD/45252 co-financed by QREN-POPH program of the EU) and of 11 MiNaXS beamline of DESY – Hamburg, Germany. This work was also supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2013 and the project Matepro –Optimizing Materials and Processes”, ref. NORTE-07-0124-FEDER- 000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 – O Novo Norte), under the “Quadro de Referência Estratégico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER)

Water Quality, Sediment Characteristics and Benthic Status of the Razim-Sinoie Lagoon System, Romania

Razim Lake is the biggest of Romania’s freshwater lakes and along with other basins as Golovita, Zmeica and Sinoie constitutes a system of great ecological significance, playing also an essential role in the supply of water for irrigation, fishery exploitation, farming, flood prevention, recreational navigation and water tourism. Due to their importance, the environmental conditions in the Razim - Sinoie coastal lakes have attracted an increased public attention in contemporary society. To assess the levels, dissemination and potential sources of contamination in the above-mentioned lagoon system, random sampling was used to collect water and sediment samples from every lake and several analytical techniques were performed to investigate their environmental characteristics. The results obtained from this study indicated that, in water, concentrations of various physico-chemical parameters are, mostly, in agreement with correlated environmental standards. Slight variations and/or occasional exceeding of the maximum admissible limits were generally limited to small areas showing levels that would not warrant special concern. In sediments, the mean concentrations of some specific trace metals were below the levels of potential effect. Benthic samples revealed 31 taxa belonging to 16 zoo-benthal subdivisions. The results of this study showed good ecological status despite local several natural and anthropogenic stressors as fishery exploitation, farming, recreational navigation and water tourism

Chlorophyll a distribution in the Romanian Black Sea inner shelf waters in 2009 .

Abstract. In 2009, seasonal and spatial variability of surface chlorophyll a in Romanian inner shelf waters was studied on the basis of samples collected during four seasonal cruises conducted both in the Danube mouths and Constanta areas. The seasonal distribution showed three peaks; the first one was recorded in February (6.22 ± 2.63 μg/l), followed by a more pronounced one in early May (9.47 ± 6.88 μg/l) corresponding to the Danube’s higher discharges in spring. After a relatively low chlorophyll a in July, there was found the third peak in September (10.29 ± 8.18 μg/l) as a result of a strong diatoms bloom in the Portita area (south of the Danube mouths). Except for winter, the spatial distribution of surface chlorophyll a was characterized by high variability; the chlorophyll a concentrations measured in the Danube mouths area, especially in shallower stations along the Portita profile (> 20 μg/l in May and September), were much higher than those recorded on transect East-Constanta

Effect of crystallization ambient on orientation selection in Sol-Gel derived Pb(Zr,Ti)O-3 thin films on Pt electrode layers

Studies are presented on the role of poe in orientation selection during crystallization annealing of sol-gel derived PZT films on Pt electrode layers. Residual organics, left in the film after a short (10 s) pyrolysis step at 350C, result in a sharp (111) PZT fiber texture in the crystallized films. Meanwhile, longer pyrolysis times, resulting in complete removal of all oxidizable carbon from the film, result in mixed (111)/(100) oriented films. These results suggest that a reduced pO2 at the PZT/Pt interface, caused by residual organic burnoff during the crystallization step, plays an essential role in the nucleation of (111) grains. Very thin (< 100 nm) films crystallized in air are fully (100)) oriented, presumably because due to the greater transparency of these films to ambient O2, nucleation of (111) grains is entirely suppressed. By performing the crystallization in N2, the sharp (111) orientation could be recovered, confirming pO2 as the key factor controlling orientation selection in very thin films.status: publishe