A review on mechanism and future perspectives of cadmium-resistant bacteria     

S. Z. Abbas  M. Rafatullah  K. Hossain  N. Ismail  H. A. Tajarudin  H. P. S. Abdul Khalil 《International Journal of Environmental Science and Technology》2018,15(1):243-262

Since the last few decades, cadmium anthropocentric sources have been increased drastically. Various chemical and physical approaches for cadmium remediation have been proposed, but these techniques are quite expensive, not healthy for the environment and not efficient at the low concentration of cadmium. Thus, in the last few years, the cadmium removal by biological approaches has received a great interest. Many bacteria can resist against high concentration of cadmium through different mechanisms. The cadmium-resistant bacteria can be grouped into three levels. The main group consists of bacteria which efflux the cadmium from the cells. The bacteria of the other two groups are capable of detoxifying or binding cadmium. The cadA and cadB gene systems are involved in efflux mechanism, and these encode different efflux pump proteins, while the functional groups such as amine, carboxyl, phosphate and hydroxyl facilitate cadmium binding to bacterial surface such as chemisorption. Many enzymes are involved in the detoxifying the cadmium and make the membrane impermeable against cadmium. This paper also reviews the industrial application of cadmium-resistant bacteria and the future perspectives of genetic engineering, bioelectrochemical system, microbial aggregates and biosorption of cadmium by algae.  相似文献   

Hydrogeochemistry and groundwater quality assessment of the multilayered aquifer in Lower Kelantan Basin,Kelantan, Malaysia     

Anuar Sefie  Ahmad Zaharin Aris  Mohammad Firuz Ramli  Tahoora Sheikhy Narany  Mohd Khairul Nizar Shamsuddin  Syaiful Bahren Saadudin  Munirah Abdul Zali 《Environmental Earth Sciences》2018,77(10):397

Continual expansion of population density, urbanization, agriculture, and industry in most parts of the world has increased the generation of pollution, which contributes to the deterioration of surface water quality. This causes the dependence on groundwater sources for their daily needs to accumulate day by day, which raises concerns about their quality and hydrogeochemistry. This study was carried out to increase understanding of the geological setup and assess the groundwater hydrogeochemical characteristics of the multilayered aquifers in Lower Kelantan Basin. Based on lithological data correlation of exploration wells, the study area can be divided into three main aquifers: shallow, intermediate and deep aquifers. From these three aquifers, 101 groundwater samples were collected and analyzed for various parameters. The results showed that pH values in the shallow, intermediate and deep aquifers were generally acidic to slightly alkaline. The sequences of major cations and anions were Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and HCO₃^? > Cl^? > SO₄^2? > CO₃^2?, respectively. In the intermediate aquifer, the influence of ancient seawater was the primary factor that contributed to the elevated values of electrical conductivity (EC), Cl^? and total dissolved solids (TDS). The main facies in the shallow aquifer were Ca–HCO₃ and Na–HCO₃ water types. The water types were dominated by Na–Cl and Na–HCO₃ in the intermediate aquifer and by Na–HCO₃ in the deep aquifer. The Gibbs diagram reveals that the majority of groundwater samples belonged to the deep aquifer and fell in the rock dominance zone. Shallow aquifer samples mostly fell in the rainfall zone, suggesting that this aquifer is affected by anthropogenic activities. In contrast, the results suggest that the deep aquifer is heavily influenced by natural processes.  相似文献   

Assessing flood inundation mapping through estimated discharge using GIS and HEC-RAS model     

Ernieza Suhana Mokhtar  Biswajeet Pradhan  Abd Halim Ghazali  Helmi Zulhaidi Mohd Shafri 《Arabian Journal of Geosciences》2018,11(21):682

Water discharge is the main parameter in hydraulic modeling for flood hazard assessment. However, the unavailability of data on discharge and observed river morphologies resulted in erroneous calculations and irregularities in flood inundation mapping. The objectives of this study are (i) to investigate uncertainties of hydraulic parameters (width, cross-sectional depth, and channel slope) used in discharge equation and (ii) to examine the influence of estimate discharge on water extent and flood depth with different boundary conditions on interferometric synthetic aperture radar (IFSAR) and modified IFSAR DEMs. Sensitivity analysis was conducted with the Monte Carlo simulation method to generate random data combinations. Bjerklie’s equation was used to calculate discharge based on the three variables, and Manning’s n was substituted into the Hydrologic Engineering Center River Analysis System (HEC-RAS) model. TerraSAR-X was used to distinguish existing flood water bodies and normal water extent. The uncertainty of the combined variables was assessed with the likelihood measures such as F-statistic, mean absolute error, root mean square error, and Nash–Sutcliffe efficiency which compares observed and predicted inundated area as well as flood water depth simulated using the HEC-RAS model.  相似文献   

Conditioning generative adversarial networks on nonlinear data for subsurface flow model calibration and uncertainty quantification     

Razak  Syamil Mohd  Jafarpour  Behnam 《Computational Geosciences》2022,26(1):29-52

Conditioning complex subsurface flow models on nonlinear data is complicated by the need to preserve the expected geological connectivity patterns to maintain solution plausibility. Generative adversarial networks (GANs) have recently been proposed as a promising approach for low-dimensional representation of complex high-dimensional images. The method has also been adopted for low-rank parameterization of complex geologic models to facilitate uncertainty quantification workflows. A difficulty in adopting these methods for subsurface flow modeling is the complexity associated with nonlinear flow data conditioning. While conditional GAN (CGAN) can condition simulated images on labels, application to subsurface problems requires efficient conditioning workflows for nonlinear data, which is far more complex. We present two approaches for generating flow-conditioned models with complex spatial patterns using GAN. The first method is through conditional GAN, whereby a production response label is used as an auxiliary input during the training stage of GAN. The production label is derived from clustering of the flow responses of the prior model realizations (i.e., training data). The underlying assumption of this approach is that GAN can learn the association between the spatial features corresponding to the production responses within each cluster. An alternative method is to use a subset of samples from the training data that are within a certain distance from the observed flow responses and use them as training data within GAN to generate new model realizations. In this case, GAN is not required to learn the nonlinear relation between production responses and spatial patterns. Instead, it is tasked to learn the patterns in the selected realizations that provide a close match to the observed data. The conditional low-dimensional parameterization for complex geologic models with diverse spatial features (i.e., when multiple geologic scenarios are plausible) performed by GAN allows for exploring the spatial variability in the conditional realizations, which can be critical for decision-making. We present and discuss the important properties of GAN for data conditioning using several examples with increasing complexity.

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Smooth particle hydrodynamics modelling of liquid-sediment system and coastal wave breaker     

Ng  Fei Chong  Zawawi  Mohd Hafiz  Azman  Aqil  Abas  Aizat  Razak  Norizham Abdul  Aziz  Nurhanani A.  Zahari  Nazirul Mubin 《Ocean Dynamics》2022,72(2):99-114

Ocean Dynamics - In this paper, a two-phase coastal liquid-sediment system and a wave breaker were numerically simulated using a particle-based smooth particle hydrodynamics (SPH). To verify the...  相似文献   

The nexus between income inequality,economic growth and environmental degradation in Pakistan     

Amdadullah Baloch  Said Zamin Shah  Zaleha Mohd Noor  Hussian Bakhsh Magsi 《GeoJournal》2018,83(2):207-222

This study examines the impact of income inequality and economic growth on environmental degradation in Pakistan using ARDL bounds testing approach for the period 1966–2011. Empirical results for the aggregate CO₂ emissions and its four sources such as CO₂ emissions from solid fuel, liquid fuel and gaseous fuel consumption as well as electricity and heat production confirm the existence of long run co-integrated relationship between income inequality, economic growth and environment degradation. The estimated results indicate that carbon emissions increase as the income gap expands in Pakistan. Besides the negative impact of industrial share and population density on CO₂ emissions, we also confirm that economic growth in Pakistan comes up with higher emissions. Hence, the hypothesis of EKC is not valid for Pakistan during the study period. Our empirical findings are robust as evidenced by dynamic ordinary least squared and the U-tests. Overall, this study suggests that the distribution of income matters to aggregate carbon emissions and focus should be made on sustained economic growth to reduce pollutants and hence CO₂ emission in the study area.  相似文献   

Group velocity dispersion analysis in northern Peninsular Malaysia     

Syed Mustafizur Rahman  Md. Omar Faruk  Md. Habibur Rahman  Mumnunul Keramat  Mohd Nawawi  Faisal Kamal Zaidi 《Arabian Journal of Geosciences》2016,9(13):623

The crustal structure beneath three seismic stations over Malaysia has been investigated with the application of the group velocity dispersion analysis of the northern Sumatra earthquake data which occurred on 06 April 2010. Eighteen crustal layer models are constructed to assess the structure. Group velocity dispersions have been computed for the recorded earthquake data using a graphical method and modified Haskell matrix method for the models. Both dispersions have been presented for the interpretation of crustal layers. Findings have shown four major crustal layers having thicknesses of 2.5–4.0, 2.0–5.5, 5.0–8.0, and 8.5–9.0 km, while in Terengganu, it has shown three layers. Density, shear, and compressional wave velocities used in models have suggested that the crustal structure of the northern part of Peninsular Malaysia is crystalline. Major crustal minerals are of quartz, plagioclase, and mica. Most layers seem to have upward directions toward Perak from Kedah and Terengganu.  相似文献   

PITCHER PLANTS RECORDED FROM BRIS FOREST IN JAMBU BONGKOK, KUALA TRENGGANU, MALAYSIA     

Jumaat H Adam　Nurulhuda Edy Muslim　Abdul Halim Hashim　Abd Rahim Othman　Hafiza Abd Hamid　Gire Kibe Gopir　Lydia M Pilik　Ramlan Omar　Muhammad Barzani Qasim　Jumat Salimon　Sahibin Abd Rahim 　Marlia Mohd Hanafiah 《湿地科学》2005,3(3):183-189

1INTRODUCTION NepentheswhichareknownlocallyinPeninsular Malaysiaasperiukkerabelongtoamonogenericfami lyNepenthaceae.Atpresent,atotalofninespecies(excludingnaturalhybrids)arerecordedfromPenin sularMalaysia.Ofthese,fourspeciesareendemic,whilsttheotherfivespeciesarefoundoutsidethepen insula.Thespeciescanarbitrarilybeclassifiedinto thelowlandspeciesandthehighlandspecies(Clarke,2002;Shivas,1984;Kurata,1976).Threespeciesarefoundinthehighlandhabitatscom monlyatanelevationofabove1000mforaboves…  相似文献   

Zinc and Copper Concentrations in Two Species of Intertidal Crabs from the Middle of the West Coast of Peninsular Malaysia     

Ahmad Ismail  Chee Kong Yap 《湿地科学》2009,7(3):218-229

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Experimental evaluation of force analogy method (FAM) by element type     

Toloue  Iraj  Liew  Mohd Shahir  Harahap  Indra Sati Hamonangan  Lee  Hsiu Eik 《地震工程与工程振动(英文版)》2020,19(1):137-147

The force analogy method(FAM) is considered as one of the most time-saving and cost-efficient methods for analyzing frames. Through a set of assumptions and restoring forces, FAM analyzes nonlinear frames responses through Hooke's law. This study evaluates the effect of element type on FAM through numerical and experimental tests. The conventional Euler Bernoulli(EB) element is replaced by the Timoshenko(TS) beam-column element and the results are interpreted and compared with experimental findings. Three experimental tests were conducted for benchmarking and comparison purposes via 2 D aluminum frames. The results indicated that during the analysis, when the frame response is in the linear region, there is no difference between the element types in the response of the frames. When the frame entered the plastic region, the frames which were analyzed by the TS element revealed closer responses to the experimental outcomes. The gap between the results of the frame which was analyzed by EB and TS enlarged especially when the frame experienced a sharp or huge rotation of more than 0.2 rad. The final recorded deformations based on the TS element revealed an accuracy between 98.05% to 98.65%, while the EB element showed 14.66% to 45.14% for rotations of more than 0.2 rad at plastic hinge locations(PHLs).  相似文献