Heavy metal biosorption potential of a Malaysian Rhodophyte (<Emphasis Type="Italic">Eucheuma denticulatum</Emphasis>) from aqueous solutions     

Md. S. Rahman  K. V. Sathasivam 《International Journal of Environmental Science and Technology》2016,13(8):1973-1988

Biosorption is a promising technology for the removal of heavy metals from industrial wastes and effluents. In the present study, biosorption of Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺ onto the dried biomass of Eucheuma denticulatum (Rhodophyte) was investigated as a function of solution pH, contact time, temperature and initial metal ion concentration. The experimental data were evaluated by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The sorption isotherm data followed Langmuir and Freundlich models, and the maximum Langmuir monolayer biosorption capacity was found as 81.97, 66.23, 51.02 and 43.48 mg g^?1 for Pb²⁺, Cu²⁺, Fe²⁺ and Zn²⁺, respectively. The sorption kinetic data followed pseudo-second-order and intraparticle diffusion models. Thermodynamic study revealed feasible, spontaneous and endothermic nature of the sorption process. Fourier transform infrared analysis showed the presence of amine, aliphatic, carboxylate, carboxyl, sulfonate and ether groups in the cell wall matrix involved in metal biosorption process. A total of nine error functions were applied in order to evaluate the best-fitting models. We strongly suggest the analysis of error functions for evaluating the fitness of the isotherm and kinetic models. The present work shows that E. denticulatum can be a promising low-cost biosorbent for removal of the experimental heavy metals from aqueous solutions. Further study is warranted to evaluate its potential for the removal of heavy metals from the real environment.  相似文献   

Multiple step ahead river flow modelling for south east tasmanian aquaculture     

Md. Sumon Shahriar  Mohammad Kamruzzaman  John McCulloch  Simon Beecham 《Earth Science Informatics》2016,9(3):271-279

We develop multiple step ahead prediction models of river flow for locations in Tasmania (Australia) for decision support in aquaculture. In predicting river flows for multiple days ahead, we first statistically determine the maximum input lags of rainfall and river flow. We then use machine learning techniques in building models. In multiple step ahead prediction, we consider both static and dynamic approaches. In dynamic approach, one day prediction is served as input to two days ahead prediction. The experimental results demonstrate that, in general, a dynamic approach provides better accuracy in multiple day’s ahead prediction. For Duck Bay location using dynamic approach, support vector regression performs best over linear regression, M5P and multilayer perceptron. However, at Montagu Bay location, we find that M5P performs best over methods. We find that multiple step ahead prediction of river flow for each location requires modelling of lags with associated machine learning techniques.  相似文献   

Hybrid off-river augmentation system as an alternative raw water resource: the hydrogeochemistry of abandoned mining ponds     

Faradiella Mohd Kusin  Mohd Syakirin Md Zahar  Siti Nurjaliah Muhammad  Nur Diyana Mohamad  Zafira Md Zin  Sharifah Mohd Sharif 《Environmental Earth Sciences》2016,75(3):230

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Characterization of underground tunnel water hydrochemical system and uses through multivariate statistical methods: a case study from Maddhapara Granite Mine,Dinajpur, Bangladesh     

M. Farhad Howladar  Md. Mustafizur Rahman 《Environmental Earth Sciences》2016,75(24):1501

A quality study of the drained water from Maddhapara Granite Mine underground tunnel was undertaken to study their hydrochemical variations and suitability for various uses employing chemical analysis, basic statistics, correlation matrix (r), cluster analysis, principal component/factor analyses, and ANOVA as the multivariate statistical methods. The results of chemical analysis of water show the modest variation in their ionic assemblage among different sampling points of the tunnel where Ca–HCO₃ type of hydrochemical facies is principally dominated. The correlation matrix shows a very strong to very weak positive, even negative, correlation relationship, suggesting the influence of different processes such as geochemical, biochemical processes, and multiple anthropogenic sources on controlling the hydrochemical evolution and variations of water in the mine area. Cluster analysis confirms that cluster 1 contains 68.75% of total samples, whereas cluster 2 contains 31.25%. On the whole, the dominated chemical ions of first cluster groups are Ca and HCO₃, suggesting a natural process similar to dissolution of carbonate minerals. The second cluster group consisted of Cl^? and SO₄ ^2? ions representing natural and anthropogenic hydrochemical process. The results of PCA/FA analysis illustrate that different processes are involved in controlling the chemical composition of groundwater in the mine area. The factor 1 loadings showed that pH, EC, TDS, Na, Mg, chloride, and sulfate which have high loading in this factor are expected to come from carbonate dissolution to oxidation conditions. One-way ANOVA describes the significance of dependent variables with respect to independent variables. ANOVA gives us the idea that EC, K⁺, Fe^total, SO ₄ ² , As, and Pb are the most important factors in controlling spatial differences in water quality in this tunnel. But different results have been encountered for different independent variables which might be due to dissimilar sources of water. From the qualitative analysis, it is clear that water quality is not very favorable for aquatic creatures as well as for drinking purposes. The water can be used for irrigation purposes without any doubt as SAR and RSC analysis provides good results. Moreover, the results of this research confirmed that the application of multivariate statistical analysis methods is apposite to inferring complex water quality data sets with its possible pollution sources. At the end, this research recommends (1) as water becomes more and more important, water treatment plants should be built before the water being used; (2) a detailed water step utilization plan should be set beforehand to guarantee tunnel water being used effectively; and (3) after the water being used for agriculture, elements in crops should be monitored continuously to ensure that ions and compounds that come from the tunnel water are lower than guideline values for human beings health.  相似文献   

Statistical downscaling of rainfall: a non-stationary and multi-resolution approach     

Md. Mamunur Rashid  Simon Beecham  Rezaul Kabir Chowdhury 《Theoretical and Applied Climatology》2016,124(3-4):919-933

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Detecting climate adaptation with mobile network data in Bangladesh: anomalies in communication,mobility and consumption patterns during cyclone Mahasen     

Xin Lu  David J. Wrathall  Pål Roe Sundsøy  Md. Nadiruzzaman  Erik Wetter  Asif Iqbal  Taimur Qureshi  Andrew J. Tatem  Geoffrey S. Canright  Kenth Engø-Monsen  Linus Bengtsson 《Climatic change》2016,138(3-4):505-519

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Spatio-temporal analysis of warming in Bangladesh using recent observed temperature data and GIS     

Md. Rejaur Rahman  Habibah Lateh 《Climate Dynamics》2016,46(9-10):2943-2960

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Estimation of daily average net radiation and its variation over West Bengal,India using MODIS products     

Dibyendu Dutta  Prachi Goel  Manisha Singh  Vinay Kumar Dadhwal  Rodda Suraj Reddy 《国际地球制图》2017,32(3):286-297

A simple and exclusively satellite-based instantaneous net radiation (INR) and its components have been estimated and it is based on the method proposed. The method has been used to check its suitability over West Bengal, India on clear sky days which is eliminating the need for ground-based observations. The method explicitly recognizes the need for spatially varied input parameters to estimate net radiation using remote sensing information and provides a distributed daily average net radiation map with finer spatial resolution. The satellite-derived radiative flux components were compared with the Eddy Flux Tower measurements located at Bonnie camp within mangrove forest. The bias, root-mean square error and R² between modelled and measured INR are 52.07, 49.5 W m^?2 and 0.74, respectively which are within the acceptable limit. The errors in the downward short wave and long wave as well as upward short-wave and long-wave radiative flux are 13.78, 3.54, 12.41 and 3.54%, respectively. Further, variations of all the radiative flux components were analysed over different eco-systems.  相似文献   

On the photo-gravitational restricted four-body problem with variable mass     

Amit Mittal  Rajiv Agarwal  Md Sanam Suraj  Monika Arora 《Astrophysics and Space Science》2018,363(5):109

This paper deals with the photo-gravitational restricted four-body problem (PR4BP) with variable mass. Following the procedure given by Gascheau (C. R. 16:393–394, 1843) and Routh (Proc. Lond. Math. Soc. 6:86–97, 1875), the conditions of linear stability of Lagrange triangle solution in the PR4BP are determined. The three radiating primaries having masses \(m_{1}\), \(m_{2}\) and \(m_{3}\) in an equilateral triangle with \(m_{2}=m_{3}\) will be stable as long as they satisfy the linear stability condition of the Lagrangian triangle solution. We have derived the equations of motion of the mentioned problem and observed that there exist eight libration points for a fixed value of parameters \(\gamma (\frac{m \ \text{at time} \ t}{m \ \text{at initial time}}, 0<\gamma\leq1 )\), \(\alpha\) (the proportionality constant in Jeans’ law (Astronomy and Cosmogony, Cambridge University Press, Cambridge, 1928), \(0\leq\alpha\leq2.2\)), the mass parameter \(\mu=0.005\) and radiation parameters \(q_{i}, (0< q_{i}\leq1, i=1, 2, 3)\). All the libration points are non-collinear if \(q_{2}\neq q_{3}\). It has been observed that the collinear and out-of-plane libration points also exist for \(q_{2}=q_{3}\). In all the cases, each libration point is found to be unstable. Further, zero velocity curves (ZVCs) and Newton–Raphson basins of attraction are also discussed.  相似文献   

Simultaneous monitoring of soil 222Rn in the Eastern Himalayas and the geothermal region of eastern India: an earthquake precursor     

Chowdhury  Saheli  Deb  Argha  Barman  Chiranjib  Nurujjaman  Md.  Bora  Dipok K. 《Natural Hazards》2022,112(2):1477-1502

Natural Hazards - Activity of 222Rn gas in soil has been recorded continuously at three monitoring centres, namely Ravangla and Diphu in the Eastern Himalayan region and Tantloi in the geothermal...  相似文献