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Coconut jute carbon, a waste by-product, was utilized in the production of activated carbon. The activated carbon was then evaluated for colour removal from pulp and paper mill wastewater. The activation of the coconut jute was evaluated using a fixed bed reactor involving carbonization and activation steps at temperatures of 650°C in the absence of air. The activation results showed that the maximum surface area of the activated coconut jute carbon (ACJC) was 94 m²g-1. Adsorption equilibrium results of the pulp paper mill wastewater on the ACJC showed that a significant amount of colour reduction was achieved when the ACJC dose exceeded 8 to 12gl-1. Batch equilibrium data was used to develop adsorption isotherms for colour removal. Based on those isotherms, the amount of activated coconut jute carbon required to achieve colour removal can be predicted. Apart from reducing colour from the effluent, a waste disposal problem is also solved by utilizing this material as an adsorbent. [ABSTRACT FROM AUTHOR]

The Nemunas River basin falls within the territories of five different countries - Belarus, Lithuania, Russia, Poland and Latvia. In general, the beginning of spring floods highly depends on rapid rise of air temperature, heavy precipitation and sudden snow melting in the analysed basin. In this paper, the conditions of formation and consequences of two catastrophic floods in 1958 and 1979 in the Nemunas River basin were studied regarding the hydrometeorological parameters (maximum snow water equivalent before the beginning of flood and precipitation amount during the flood) as well as runoff coefficients for each selected catastrophic flood. Differences between the main drivers and evolution of these floods were analysed. Spatial distribution of maximum snow water equivalent and precipitation, as well as runoff coefficient in different parts of the river basin, were identified as having the most significant impact on the formation of the studied catastrophic floods. [ABSTRACT FROM AUTHOR]

Dewpoint temperature (Tdew) plays a key role in agricultural issues as well as meteorological studies. This paper is aimed at developing and validating prediction and estimation models of Tdew values. Gene expression programming (GEP), multivariate adaptive regression spline (MARS), and random forest (RF) models were employed. Data from six weather stations (consisting of a period of ten years) in East Azerbaijan, northwestern Iran were utilized for establishing, testing, and validating the models. In the case of predicting models, chronological records of Tdew in previous time steps were introduced as models' inputs to predict Tdew values at daily and weekly prediction intervals. In the case of Tdew estimating models, daily records of mean air temperature, sunshine hours, relative humidity, and wind speed were utilized as inputs to estimate Tdew. Acquired results showed prediction-based GEP surpasses the MARS and RF models in both daily and weekly prediction intervals. Among the estimation models, the MARS models that relied on air temperature, relative humidity, and sunshine hours presented the most accurate results in all studied locations as well as the studied region. The current study proposes the use of MARS models in estimating Tdew magnitudes, while it criticizes the use of single data set assignment for both temporal and spatial analysis. [ABSTRACT FROM AUTHOR]

In this paper, poly(vinyl alcohol) (PVA) nanofiber was prepared and modified by diethylenetriamine (DETA) and ethylenediamine (EDA) in presence of glutaraldehyde (GA). Dye removal ability of the modified nanofiber (PVA/DETA/EDA/GA) as a nanoadsorbent from water was studied. Fourier transform Infrared and SEM were used to investigate the characteristics of the modified nanofiber. Direct Red 23 (DR23) and Direct Blue (DB78) were used. The effect of operational parameters such as pH, initial dye concentration, contact time, temperature and adsorbent dosage on dye removal was studied. The dye adsorption isotherms, kinetics and thermodynamics were investigated. The maximum dye adsorption capacity of the modified nanofiber was 370 and 400 mg/g for DR23 and DB78, respectively. Four isotherms, the Langmuir, the Freundlich, Tempkin and a modified Langmuir-Freundlich models were used. Dye adsorption on the modified nanofiber followed the Langmuir isotherm and pseudo-second kinetic order. Thermodynamic data showed that dye removal was a spontaneous, endothermic and physisorption process. [ABSTRACT FROM AUTHOR]

The ice regime of rivers is considered a sensitive indicator of climate change. This paper summarises the results of research on the long-term changes in the ice regime parameters under changing climate conditions and their regional peculiarities in Latvia from 1945 to 2012. The ice cover duration on Latvian rivers has decreased during recent decades. The research results demonstrated that there is a positive trend as regards the formation of the ice cover and in 31.8% of the cases the trend is statistically significant at p < 0.05. As regards the breaking up of ice, there is a statistically significant negative trend in 93.2% of the cases at p < 0.05. This indicates an earlier ice break-up date, which in turn, displays a strong correlation with the increase of the air temperature. The same pattern applies to the reduction of the length of ice cover (a statistically significant trend in 86.4% of the cases at p < 0.05). In approximately 60% of the cases, there is a statistically significant reduction of the ice thickness. The estimated winter severity index indicates warmer winters over the last 20 years as well as regional differences in the west-east direction. [ABSTRACT FROM AUTHOR]

The Penman-Monteith equation (FAO-56) is accepted as the standard model for estimating reference evapotranspiration (ETo). However, the major obstacle to using FAO-56 widely is that it requires numerous climatic data. The Hargreaves-Samani (HS) method is frequently used for the calculation of ETo since it is based on measurements of daily minimum and maximum air temperature alone. Those are commonly recorded at many meteorological stations throughout the world. It is the objective of this paper to evaluate the quality of HS and calibrate the coefficients of this method for different climates as represented by the Köppen classification. Estimated values are compared with Penman-Monteith ETo values in terms of the coefficient of efficiency Ceff as well as the root mean square error, the mean absolute error and the Bayes information criterion. The Penman-Monteith equation for ETo (FAO-56) is based on physics and known to provide best estimates of ETo. The results of our work show that the correlation between long-term monthly means of HS and FAO-56 can be improved significantly by introducing climate-class specific coefficients. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the uncertainty ranges of high flows under climate change in Jinhua River basin, eastern China. Four representative concentration pathways (RCPs), three global climate models (GCMs), 10 downscaling parameter sets and three hydrologic models are applied to simulate future discharges. Changes of annual maximum discharges are assessed for the baseline period (1961-1990) and future period (2011-2040). The uncertainties of annual maximum discharges are calculated for each uncertainty source and compared with different combinations of them. The minimum temperature will probably increase all year round in the future period and maximum temperature would increase in most cases. The changes of precipitation showed different directions by different models and emission scenarios. The annual maximum discharges would decrease for all RCPs. The order of uncertainty ranges of high flows due to different uncertainty sources from high to low is: hydrologic models, GCMs, parameter sets in the downscaling method and emission scenarios. It must be noted that the small uncertainty contribution from different emission scenarios is due to the study period when the differences in increase of radiative forcing and greenhouse gas concentration are less obvious between different RCPs compared to the second half of the 21st century. [ABSTRACT FROM AUTHOR]

The removal of chromium(III) (Cr(III)) from industrial wastewater by various low-cost methods has been widely investigated. In this paper, a type of bio-adsorbent was prepared using rice straw modified by fermentation and simple chemical treatment. The aim is to detect the adsorption mechanism and characteristics on Cr(III) ions. The analysis shows that the bio-adsorbent possesses four modified characteristics for Cr(III) adsorption. The first one is the acquired physical adsorption involving concave and convex structures. The second one is the effects of the hydrogen bonding surface hydroxyl groups and the metal chromium ion with complexation. The third one is mainly caused by hydrophilic active groups that possess carboxyl and hydroxyl groups during microbial degradation to combine with ions. The final one is the bio-adsorbent had high adsorption for low concentration of Cr(III) ions. The highest removal of around 97.45% was obtained at pH 5.0, bioadsorption dosage of 0.5 g L-1, and initial Cr(III) concentration of 20 mg L-1. The adsorption process followed the pseudo second-order model (R2>0.99), while the isotherms were fitted to the Freundlich equation (68.1926 mg g-1), mainly by chemical adsorption. This study demonstrates the potential of using this biosorbent to remove Cr(III) from both synthetic and industrial wastewater. [ABSTRACT FROM AUTHOR]

We analyse the change trends of the annual and seasonal runoff series of the hydrological station Batang on the headstream of the Yangtze River over the period 1960-2007. The relations between runoff series and precipitation and temperature conditions are investigated, and the influence of the refreezing process of meltwater of the glaciers on the Yangtze River flow is examined with the proposed accumulated temperature deficit (ATD) index. It is found that annual runoff at the Batang station is not stable during the period 1960-2007. From 1960 to 1980, there was a rather strong decrease of 14.4 m³ s-1 year-1 on average in spite of the statistically significant increase in air temperature and rather stable precipitation. It is argued that the annual rate of glacier runoff generation is possibly controlled by the ATD rather than by the direct air temperature. Seasonal analysis indicates that ATD might be of greater influence in autumn and winter in affecting runoff than in spring and summer. The research in this paper may be helpful in understanding how the hydro-climatic conditions affect runoff generation in the cold regions. [ABSTRACT FROM AUTHOR]

In this paper, a new kind of poly(acrylic acid) modified clay adsorbent, the poly(acrylic acid)/bentonite composite (PAA/HB) was prepared by in-situ polymerization, and utilized to remove lead(II) ions from solutions. The maximum adsorption of adsorbent is at pH 5 for metal ions, whereas the adsorption starts at pH 2. The effects of contact time (5-60 min), initial concentration of metal ions (200 - 1,000 mg/L) and adsorbent dosage (0.04-0.12 g/100 mL) have been reported in this article. The experimental data were investigated by means of kinetic and equilibrium adsorption isotherms. The kinetic data were analyzed by the pseudo-first-order and pseudo-second-order equation. The experimental data fitted the pseudo-second-order kinetic model very well. Langmuir and Freundlich isotherms were tried for the system to better understand the adsorption isotherm process. The maximal adsorption capacity of the lead(II) ions on the PAA/HB, as calculated from the Langmuir model, was 769.2 mg/g. The results in this study indicated that PAA/HB was an attractive candidate for removing lead(II) (99%). [ABSTRACT FROM AUTHOR]