Litterfall of three subtropical mangrove species in the family Rhizophoraceae     

Md. Kamruzzaman  Sahadev Sharma  A. T. M. Rafiqul Hoque  Akio Hagihara 《Journal of Oceanography》2012,68(6):841-850

This study was conducted to evaluate and compare the litterfall dynamics of three mangrove species in the family Rhizophoraceae: Rhizophora stylosa, Kandelia obovata, and Bruguiera gymnorrhiza, in Manko Wetland, Okinawa Island, Japan. Over 3?years, these species showed highest litterfall of leaves and stipules in summer and the lowest litterfall in winter. Litterfall of flowers and fruits peaked in July for R. stylosa, and in August and again in October?CNovember for K. obovata. Litterfall of flower buds, flowers, and propagules occurred throughout the year for B. gymnorrhiza, but was highest in summer. Litterfall of propagules was highest in September and May for R. stylosa and K. obovata, respectively. Kendall??s coefficient of concordance revealed that the monthly changes for leaf, stipule, flower, and fruit litterfalls of all the species were strongly and significantly concordant among the years. The conversion rate of flowers to propagules was 2.3?% in R. stylosa, 5.9?% in K. obovata, and 10.3?% in B. gymnorrhiza. Total annual litterfall in R. stylosa was significantly different from K. obovata and B. gymnorrhiza; however, the latter two species showed no significant differences. Leaves contributed the most to the total litterfall of all three species, and represented 58.4, 54.0, and 50.4?% of the total litterfall for R. stylosa, K. obovata, and B. gymnorrhiza, respectively. Except for branches and flower bud primordia, all other components of litterfall had clear annual cycles for all three species. Rhizophora stylosa and K. obovata showed a negative correlation between leaf production and reproductive organ production, but B. gymnorrhiza tended to increase leaf production with increasing reproductive organ production.  相似文献   

Agrobiodiversity of Muda Rice Agroecosystem:A case Study in Largest Granary Area of Malaysia     

Amir Shah Ruddin Md Shah　Mashhor Mansor　Shahrul Anuar Mohd Shah　Che Salmah Mohd Rawi　Abu Hassan Ahmad　Ibrahim Jaafar 《湿地科学》2008,6(1):34-44

A survey was carried out at the largest rice cultivation area in Peninsular Malaysia,the Muda rice agroecosystem.The main objective of this study was to document the overall biodiversity associated with this unique agroecosystem by using a combination of sampling techniques in order to record different groups of fauna and flora.The total number of biota recorded and identified from the rice field ecosystem during the study period consisted of 46 species of zooplankton,81 species of aquatic insects,5 species of rodents,7 species of bats,87 species of birds,11 species of fishes and 58 species of weeds.A long-term study should be carried out as more species are expected to be recorded when more of the Muda rice agroecosystem area has been sampled to obtain sufficient information on the Muda rice agrobiodiversity.  相似文献   

Simulation of streamflow with statistically downscaled daily rainfall using a hybrid of wavelet and GAMLSS models     

Md. Mamunur Rashid  Simon Beecham 《水文科学杂志》2013,58(11):1327-1339

ABSTRACT

A rainfall–streamflow model is proposed, in which a downscaled rainfall series and its wavelet-based decomposed sub-series at optimum lags were used as covariates in GAMLSS (Generalized Additive Model in Location, Scale and Shape). GAMLSS is applied in climate change impact assessment using CMIP5 general climate model to simulate daily streamflow in three sub-catchments of the Onkaparinga catchment, South Australia. The Spearman correlation and Nash-Sutcliffe efficiency between the observed and median simulated streamflow values were high and comparable for both the calibration and validation periods for each sub-catchment. We show that the GAMLSS has the capability to capture non-stationarity in the rainfall–streamflow process. It was also observed that the use of wavelet-based decomposed rainfall sub-series with optimum lags as covariates in the GAMLSS model captures the underlying physics of the rainfall–streamflow process. The development and application of an empirical rainfall–streamflow model that can be used to assess the impact of catchment-scale climate change on streamflow is demonstrated.  相似文献   

Baseline metals pollution profile of tropical estuaries and coastal waters of the Straits of Malacca     

Ley Juen Looi  Ahmad Zaharin Aris  Wan Lutfi Wan Johari  Fatimah Md. Yusoff  Zailina Hashim 《Marine pollution bulletin》2013

The status report on metal pollution in tropical estuaries and coastal waters is important to understand potential environmental health hazards. Detailed baseline measurements were made on physicochemical parameters (pH, temperature, redox potential, electrical conductivity, salinity, dissolved oxygen, total dissolved solid), major ions (Na, Ca, Mg, K, HCO₃, Cl, SO₄ and NO₃) and metals concentrations (²⁷Al, ⁷⁵As, ¹³⁸Ba, ⁹Be, ¹¹¹Cd, ⁵⁹Co, ⁶³Cu, ⁵²Cr, ⁵⁷Fe, ⁵⁵Mn, ⁶⁰Ni, ²⁰⁸Pb, ⁸⁰Se, ⁶⁶Zn) at estuaries and coastal waters along the Straits of Malacca. Principal component analysis (PCA) was employed to reveal potential pollution sources. Seven principal components were extracted with relation to pollution contribution from minerals-related parameters, natural and anthropogenic sources. The output from this study will generate a profound understanding on the metal pollution status and pollution risk of the estuaries and coastal system.  相似文献   

Monitoring heat losses using Landsat ETM+ thermal infrared data — a case study at Kuju fumarolic area in Japan     

Md. Bodruddoza Mia  Yasuhiro Fujimitsu 《Acta Geophysica》2013,61(5):1262-1278

To monitor heat losses using Landsat 7 thermal infrared data from 2002 to 2010 within the active fumarolic region of Kuju volcano in Japan, we used the Stefan-Boltzmann equation for radiative heat flux (RHF) estimation. Heat discharge rate (HDR) was calculated by using the relationship coefficient of RHF and HDR, obtained from two previous studies. The highest total RHF was found to be about 57.7 MW in 2002 and the lowest was about 21.1 MW in 2010. We found the highest HDR, of about 384.5 MW, in 2002 and the lowest, of about 140.8 MW, in 2010. The RHF anomalous areas were showing a declining trend during our study period. The relationship between the land surface temperature (LST) above ambient and RHF was, as expected, in a strong correlation for each result during our study period. Overall, our study was able to delineate the declining trend of heat losses that supports a previous study of similar declining trend of HDR using steam maximum diameter method from the active fumarolic region of Kuju volcano.  相似文献   

Effects of convective available potential energy,temperature and humidity on the variability of thunderstorm frequency over Bangladesh     

Wahiduzzaman  Md  Ali  Md. Arfan  Luo  Jing-Jia  Wang  Yu  Uddin  Md. Jalal  Shahid  Shamsuddin  Islam  A. R. M. Towfiqul  Mondal  Sanjit Kumar  Siddiki  Ubaydur Rahaman  Bilal  Muhammad  Qiu  Zhongfeng  Dambul  Ramzah  Eibek  Kutubuddin  Haque  Md. Emdadul 《Theoretical and Applied Climatology》2022,147(1-2):325-346

Theoretical and Applied Climatology - The present study examines the effects of convective available potential energy (CAPE), temperature and humidity on the spatiotemporal variation of...  相似文献   

Influence of El Niño–Southern Oscillation on the long-term record of floods over Bangladesh     

Wahiduzzaman  Md  Cheung  Kevin  Tang  Shaolei  Luo  Jing-Jia 《Theoretical and Applied Climatology》2022,147(1-2):173-184

Theoretical and Applied Climatology - The present study analyzed a long-term record of major floods over Bangladesh under the influence of El Niño–Southern Oscillation (ENSO). Bangladesh...  相似文献   

Beta-�� distribution and its application to hydrologic events     

Md. Sharwar Murshed  Sangil Kim  Jeong-Soo Park 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):897-911

The beta-κ distribution is a distinct case of the generalized beta distribution of the second kind. In previous studies, beta-p and beta-κ distributions have played important roles in representing extreme events, and thus, the present paper uses the beta-κ distribution. Further, this paper uses the method of moments and the method of L-moments to estimate the parameters from the beta-κ distribution, and to demonstrate the performance of the proposed model, the paper presents a simulation study using three estimation methods (including the maximum likelihood estimation method) and beta-κ and non beta-κ samples. In addition, this paper evaluates the performance of the beta-κ distribution by employing two widely used extreme value distributions (i.e., the GEV and Gumbel distributions) and two sets of actual data on extreme events.  相似文献   

Surface complexation modeling for predicting solid phase arsenic concentrations in the sediments of the Mississippi River Valley alluvial aquifer, Arkansas, USA   总被引：1，自引：0，他引：1  

Md. Salah U. Sharif  Ralph K. DavisKenneth F. Steele  Burmshik KimPhillip D. Hays  Tim M. KresseJohn A. Fazio 《Applied Geochemistry》2011,26(4):496-504

The potential health impact of As in drinking water supply systems in the Mississippi River Valley alluvial aquifer in the state of Arkansas, USA is significant. In this context it is important to understand the occurrence, distribution and mobilization of As in the Mississippi River Valley alluvial aquifer. Application of surface complexation models (SCMs) to predict the sorption behavior of As and hydrous Fe oxides (HFO) in the laboratory has increased in the last decade. However, the application of SCMs to predict the sorption of As in natural sediments has not often been reported, and such applications are greatly constrained by the lack of site-specific model parameters. Attempts have been made to use SCMs considering a component additivity (CA) approach which accounts for relative abundances of pure phases in natural sediments, followed by the addition of SCM parameters individually for each phase. Although few reliable and internally consistent sorption databases related to HFO exist, the use of SCMs using laboratory-derived sorption databases to predict the mobility of As in natural sediments has increased. This study is an attempt to evaluate the ability of the SCMs using the geochemical code PHREEQC to predict solid phase As in the sediments of the Mississippi River Valley alluvial aquifer in Arkansas. The SCM option of the double-layer model (DLM) was simulated using ferrihydrite and goethite as sorbents quantified from chemical extractions, calculated surface-site densities, published surface properties, and published laboratory-derived sorption constants for the sorbents. The model results are satisfactory for shallow wells (10.6 m below ground surface), where the redox condition is relatively oxic or mildly suboxic. However, for the deep alluvial aquifer (21-36.6 m below ground surface) where the redox condition is suboxic to anoxic, the model results are unsatisfactory.  相似文献   

Tracing subsurface migration of contaminants from an abandoned municipal landfill   总被引：1，自引：1，他引：0  

E. A. Rahim Bahaa-eldin  I. Yusoff  S. Abdul Rahim  W. Y. Wan Zuhairi  M. R. Abdul Ghani 《Environmental Earth Sciences》2011,63(5):1043-1055

This paper aims at determining of inorganic leachate contamination for a capped unsanitary landfill in the absence of hydrogeological data. The 2D geoelectrical resistivity imaging, soil physicochemical characterization, and surface water analysis were used to determine contamination load and extent of selective heavy metal contamination underneath the landfill. The positions of the contaminated subsoil and groundwater were successfully delineated in terms of low resistivity leachate plumes of <10 Ωm. Leachate migration towards the reach of Kelang River could be clearly identified from the resistivity results and elevated concentrations of Fe in the river downslope toe of the site. Concentration of Fe, Mn, Ca, Na, K, Mg, Cu, Cr, Co, Ni, Zn, and Pb was measured for the subsoil samples collected at the downslope (BKD), upslope (BKU), and the soil-waste interface (BKI), of the landfill. The concentration levels obtained for most of the analyzed heavy metals significantly exceed the normal range in typical municipal solid waste landfill sites. The measured heavy metal contamination load in the subsoil is in the following order Fe ? Mn > Zn > Pb > Cr > Cu. Taking into consideration poor physical and chemical characteristics of the local soil, these metals first seem to be attenuated naturally at near surface then remobilize unavoidably due to the soil acidic environment (pH 4.2-6.18) which in turn, may allow an easy washing of these metals in contact with the shallow groundwater table during the periodic fluctuation of the Kelang River. These heavy metals are believed to have originated from hazardous industrial waste that might have been illegally dumped at the site.  相似文献