Ecology of sandy beaches in Oman

The benthic macrofauna and physical features of 10 sandy beaches along the coast of Oman were surveyed quantitatively. This is a mesotidal regime mostly subject to low to moderate wave energy but more exposed in the south. Five northern beaches are tide-dominated, with low wave energy, and their profiles consist of a berm, a steep, swash-dominated upper shore and a broad tide-dominated terrace from mid-shore downwards. They are composed of moderately sorted fine to medium sands. Southern beaches experience greater wave energy, particularly during the summer southwest monsoon, and exhibit smoother, concave profiles with fine, fairly well sorted carbonate sand. 58 species and species groups were recorded, with crustanceans, polychaetes and molluscs dominant. In general species richness was high, at least 19–25 species per beach, but dry biomass moderate to low at 26–90g/m shoreline, with one high value of 450g/m. Total abundance was moderate at 3–73×10³ organisms/m of beach. Some zonation was evident with ocypodid crabs andTylos in the supralittoral, cirolanid isopods on the upper shore and a variety of species on the lower shore. The coast of Oman appears to constitute a single zoogeographic region, but with some regional differentiation between north and south due to varying physical conditions. Thus, OmanÕs beaches are characterized by tide-dominated morphodynamics and exceptionally high species richness.     

Occurrence, polarity and bioavailability of dissolved organic matter in the Huangpu River, China

Dissolved organic matter （DOM） plays an important role in biogeochemical cycles in aquatic ecosystem. To investigate the characteristics of DOM in Huangpu River {the last tributary of the Yangtze River）, surface water samples were collected along the river from December 2011 to June, 2013. The concentrations of dissolved organic carbon （DOC）, the absorbance and fluorescence spectrum of DOM in water samples were measured. Fluorescent DOM in the Huangpu River was decomposed into four components by the parallel factor analysis （PARAFAC）, including one humic-like substance and three protein-like substances. It showed that high spatial variability of DOC concentration was observed in the upstream water compared to the downstream water, and so did the absorbance coefficients of chromophoric dissolved organic matter and the total fluorescence intensities of different PARAFAC components of DOM. Furthermore, there was a large difference between the polarity and bioavailability of DOM in the Huangpu River. Polar compounds dominated tyrosine-like component of fluorescent DOM in all seasons. Tryptophan-like and humic-like substances had more polar fraction in summer and autumn than those in winter, while aromatic protein-like materials had the highest polar fraction in winter. Almost all of fluorescent DOM components were refractory in spring, while less than 20% of fluorescent DOM in average were biodegradable within 4 weeks in other seasons. We concluded that the spatial variation in the abundance of DOM in the Huangpu River is mainly affected by the water discharges from the Hangjiahu Plain and the seasonal difference in polarity and bioavailability of DOM is largely determined by its origins.     

Preparation and application of amino functionalized mesoporous nanofiber membrane via electrospinning for adsorption of Cr3+ from aqueous solution

Novel amino (-NH₂) functionalized mesoporous polyvinyl pyrrolidone (PVP)/SiO₂ composite nanofiber membranes were fabricated by a one-step electrospinning method using poly (vinyl alcohol) and tetraethyl orthosilicate (TEOS) mixed with cationic surfactant, cetyltrimethyl ammonium bromide (CTAB) as the structure directing agent. Ureidopropyltriethoxysilane was used for functionalization of the internal pore surfaces. The membranes were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), element analyzer and N2 adsorption-desorption isotherms. The nanofiber diameters, average pore diameters and surface areas were 100-700 nm, 2.86 nm and 873.62 m²/g, respectively. These mesoporous membranes functionalized with -NH₂ groups exhibited very high adsorptions properties based on the adsorption of Cr³⁺+ from an aqueous solution. Equilibrium adsorption was achieved after approximately 20 min and more than 97% of chromium ions in the solution were removed. The membrane could be regenerated through acidification.     

TiO2/Ag modified penta-bismuth hepta-oxide nitrate and its adsorption performance for azo dye removal

A modified hydrophilic penta-bismuth hepta-oxide nitrate (Bi₅O₇NO₃) surface was synthesized via a precipitation method using TiO₂ and Ag as modified agents. The synthesized product was characterized by different analytical techniques. The removal efficiency was evaluated using mono-and di-sulphonated azo dyes as model pollutants. Different kinetic, isotherm and diffusion models were chosen to describe the adsorption process. X-ray photoelectron spectroscopy (XPS) results revealed no noticeable differences in the chemical states of modified adsorbent when compared to pure Bi₅O₇NO₃;however, the presence of hydrophilic centres such as TiO₂ and Ag developed positively charged surface groups and improved its adsorption performance to a wide range of azo dyes. Dyes removal was found to be a function of adsorbent dosage, initial dye concentration, solution pH and temperature. The reduction of Langmuir 1,2-mixed order kinetics to the second or first-order kinetics could be successfully used to describe the adsorption of dyes onto the modified adsorbent. Mass transfer can be described by intra-particle diffusion at a certain stage, but it was not the rate limiting step that controlled the adsorption process. Homogenous behavior of adsorbent surface can be explored by applying Langmuir isotherm to fit the adsorption data.     

A review on the generation, determination and mitigation of Urban Heat Island

Urban Heat Island （UHI） is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they consume and re-radiate solar radiations, and from the anthropogenic heat sources are the main causes of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity （UHII）. The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem, which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carded out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately living in a better environment.     

碳纳米管影响无机砷(As(III)和As(V))对大型蚤毒性的研究：特定砷形态的作用

作为一种新兴的纳米材料,羟基多壁碳纳米管(OH-MWCNTs)可能与其他污染物在水环境中共存,并进一步影响它们的毒性、输移和归趋。因此,评价碳纳米管存在下砷的毒性变化需要得到更多的关注。该试验探索了在不同pH值条件下,OH-MWCNTs诱导砷(As(III)和As(V))对水生生物大型蚤的毒性变化的潜在机制。发现了H₂AsO₃^-和H₂AsO₄^-是对大型蚤毒性最大的As(III)和As(V)。比较As(III)和As(V)的结果,发现pH值是影响砷毒性最重要的因素。此外,OH-MWCNTs影响砷对大型蚤毒性的结果表明,OH-MWCNTs的存在可以提高砷的毒性。通过吸附实验进一步研究了砷与OH-MWCNTs的相互作用。OH-MWCNTs 对As(V)吸附容量高于As(III)。总而言之, OH-MWCNTs对某些形态砷的吸附是解释砷毒性增强的可靠证据。
精选自Xinghao Wang, Ruijuan Qu, Ahmed A. Allam, Jamaan Ajarem, Zhongbo Wei, Zuoyao Wang. Impact of carbon nanotubes on the toxicity of inorganic arsenic [As(III) and As(V)] to Daphnia magna: the role of the certain arsenic species. Environmental Toxicology and Chemistry: Volume 35, Issue 7, pages 1852–1859, July 2016. DOI: 10.1002/etc.3340
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3340/full
     

Water quality soft-sensor prediction in anaerobic process using deep neural network optimized by Tree-structured Parzen Estimator

● Hybrid deep-learning model is proposed for water quality prediction. ● Tree-structured Parzen Estimator is employed to optimize the neural network. ● Developed model performs well in accuracy and uncertainty. ● Usage of the proposed model can reduce carbon emission and energy consumption. Anaerobic process is regarded as a green and sustainable process due to low carbon emission and minimal energy consumption in wastewater treatment plants (WWTPs). However, some water quality metrics are not measurable in real time, thus influencing the judgment of the operators and may increase energy consumption and carbon emission. One of the solutions is using a soft-sensor prediction technique. This article introduces a water quality soft-sensor prediction method based on Bidirectional Gated Recurrent Unit (BiGRU) combined with Gaussian Progress Regression (GPR) optimized by Tree-structured Parzen Estimator (TPE). TPE automatically optimizes the hyperparameters of BiGRU, and BiGRU is trained to obtain the point prediction with GPR for the interval prediction. Then, a case study applying this prediction method for an actual anaerobic process (2500 m³/d) is carried out. Results show that TPE effectively optimizes the hyperparameters of BiGRU. For point prediction of COD_eff and biogas yield, R² values of BiGRU, which are 0.973 and 0.939, respectively, are increased by 1.03%–7.61% and 1.28%–10.33%, compared with those of other models, and the valid prediction interval can be obtained. Besides, the proposed model is assessed as a reliable model for anaerobic process through the probability prediction and reliable evaluation. It is expected to provide high accuracy and reliable water quality prediction to offer basis for operators in WWTPs to control the reactor and minimize carbon emission and energy consumption.     

Developing Biocomposites Panels from Food Packaging and Textiles Wastes: Physical and Biological Performance

The urban solid waste problem has been one of the biggest environmental challenges these days. In this context, developing biocomposites with improved performance by using various sources and wastes has been intensified in the last decades for economic and environmental points of view. In this study, physical behavior, fungal decay and termite attack tests were conducted in laboratory conditions to investigate the performance of composites developed from TetraPak and textile wastes. All the results were compared to standard wood products. The water swelling properties strongly decreased in the manufactured TetraPak composites when compared with the conventional particleboard panels. The fungal decay resistance tests revealed that the stand alone TetraPak based composites were not completely resistant to wood-decaying fungi. A significant amelioration in the decay durability was observed for the manufactured TetraPak composites compared to the standard wood samples. Durability classes were determined according to the criteria given in the European standard (CEN/TS15083-1). Interestingly, the data indicated that the increment of the wool waste proportion in the produced boards lead to a significant enhancement counter the test fungi. The results of termite screening test showed further considerable resistance for whole TetraPak based composites against termites when compared to traditional wood samples. Such panels could be an available alternative without any additives for wood based composite structures and it can be used in a wide range of applications.     

An enhanced compost temperature sampling framework: Case study of a covered aerated static pile

Spatial and temporal temperature variations exist in a compost pile. This study demonstrates that systematic temperature sampling of a compost pile, as is widely done, tends to underestimate these variations, which in turn may lead to false conclusions about the sanitary condition of the final product. To address these variations, a proper scheme of temperature sampling needs to be used. A comparison of the results from 21 temperature data loggers randomly introduced into a compost pile with those from 20 systematically introduced data loggers showed that the mean, maximum and minimum temperatures in both methods were very similar in their magnitudes. Overall, greater temperature variation was captured using the random method. In addition, 95% of the probes introduced systematically had attained thermophilic sanitation conditions (?55 °C for three consecutive days), as compared to 76% from the group that were randomly introduced. Furthermore, it was found that, from a statistical standpoint, readings from at least 47 randomly introduced temperature loggers are necessary to capture the observed temperature variation. Lastly, the turning of the compost pile was found to increase the chance that any random particle would be exposed to the temperature ?55 °C for three consecutive days. One turning was done during the study, and it increased the probability from 76% to nearly 85%. Using the Markov chain model it was calculated that if five turnings had been implemented on the evaluated technology, the likelihood that every particle would experience the required time–temperature condition would be 98%.