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Articles by A.K. Ahmad
Total Records ( 8 ) for A.K. Ahmad
  M. Shuhaimi-Othman , A.K. Ahmad and E.C. Lim
  A study was conducted in Bebar River, Pahang, a peat swamp river in 2005 to determine metals concentration in the water and sediment and some physical-chemical parameters. Eleven sampling stations were selected along the river. Water quality parameters were recorded at each station using a Hydrolab® Surveyor 4a system. Water and sediment samples were brought back to laboratory for metals analysis. Results show that the physical-chemical parameters of water in Bebar River were in normal range/class I (good) according to Malaysian Interim Water Quality Standard (INWQS) except for pH (class III - moderate) and dissolved oxygen in the water (class IV-V - bad). However, low values of these parameters are normal for peat water (blackwater). Metals concentration (dissolved metal) in the water (Cu, Cd, Pb, Cr and Ni) was in the range of natural concentrations. Zinc, Fe and Mn concentration were higher than recommended concentrations at some stations. Cadmium, Pb, Zn and Ni concentrations in sediment were low and in the range of natural concentrations while Cu and Cr was high at some stations. Correlation analysis show that only Cu and Cr have significant positive correlation (p<0.05) between metal concentration in the sediment and water. The importance of this sensitive ecosystem is discussed further in this study.
  A.K. Ahmad and M. Shuhaimi-Othman
  A study was conducted to determine water quality and cadmium, copper, lead and zinc concentrations in sediments and 15 fish species from Lake Chini, Pahang. Physical parameters measured were water temperature, dissolved oxygen concentration, pH and conductivity. Sequential sediment extraction was conducted to extract metals from sediment, which involves three different of non-residual fractions. Fish tissues were extracted using wet digestion method. Metals concentration in sediment and fish were measured using atomic absorption spectrophotometer AAS 4100 Perkin Elmer. According to Malaysian National Interim Water Quality Standards (INWQS), Lake Chini was classified between moderate to good quality. Lake Chini was found to have low metal concentrations in sediments and fish, which indicates no significant anthropogenic metals input to the lake. One-way ANOVA test indicated that all metal concentrations were significantly different (p<0.05) between fish species, but not between feeding behavior. Heavy metal concentrations in fish tissues were found lower than the maximum allowable limit suggested by the Malaysian Food Act, which ascertain that the fish is safe to be eaten.
  Abdulali K.A. Taweel , M. Shuhaimi-Othman and A.K. Ahmad
  Concentrations of cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni) and cobalt (Co) were measured in various organs (such as in liver, gill and muscle) of Tilapia fish (Oreochromis niloticus) which were collected from Serdang night market, Bangi night and wet markets and Kajang wet market, in Selangor, Peninsular Malaysia. The concentration of metals was measured by inductively-coupled plasma mass spectrometry (ICP-MS). The levels of metal varied as it depended on various tissues. Zinc was the dominant metal measured during this study. In general, results indicated that all studied heavy metals concentrations were significantly higher (p<0.05, two way ANOVA) in liver samples collected from all sites than gill and muscle, except for the zinc in fish liver from Serdang night market (41.87 μg g-1 dry weight (DW)) less than zinc in fish gill in the same market (55.72 μg g-1 DW). The highest Cd, Pb and Co concentration in fish liver were observed in Kajang wet market which is 0.44, 0.72 and 02.86 μg g-1 DW, respectively. Meanwhile, in fish gill, levels of Pb and Co in Serdang night market were the lowest among all sites which is 0.34 and 0.31 μg g-1 DW, while the highest in gill from Bangi wet market which is 0.63 and 0.41 μg g-1 DW, respectively. Cd, Zn, Pb and Co levels in fish muscle from Serdang night market were the lowest (0.02, 11.36, 0.10 and 0.25 μg g-1 DW, respectively), whereas the lowest Ni level was noted in fish muscle from Kajang wet market (03.84 μg g-1 DW). On the other hand, the highest Cd and Zn level were in Bangi wet market (0.03 and 16.72 μg g-1 dw, respectively). The results obtained in this study were compared with those reported in all other areas of earlier studies. All studied heavy metals levels are below the limits for fish proposed by World Health Organization and safe within the limits for human consumption in the edible part of studied fish.
  A.A. Idriss and A.K. Ahmad
  The purpose of this study were to determine the concentration of heavy metals namely copper (Cu), cadmium (Cd) and lead (Pb) in sediment and to investigate the effect of sediment pH and sediment organic matter on concentration of copper, cadmium and lead in sediment at oxidation fraction from Juru River, Penang, Malaysia. The sequential extraction procedure used in this study was based on defined fractions: exchangeable, acid reduction, oxidation and residual. The concentration of Cu, Pb and Cd in residual fraction were higher than the other fractions. Among the non-residual fractions, the concentration of heavy metals in organic matter fraction was much higher than other fractions collected from all sampling sites except for Cd. The pH of the sediment in all sites was acidic. The mean of total concentrations of Cu, Cd and Pb for the two sampling times were 667, 4.135 and Pb 927 μg g-1 dry weight, respectively. Results of organic matter analysis showed that the percentage of organic matter present in sediment samples varied throughout the river and all sites of sediments were ranged from 7.10 to 16.20%. Comparison between sampling sites using one-way analysis of variance showed that there were significant differences at exchangeable fraction for cadmium and lead while there was no significant differences for copper. At acid reduction fraction and oxidation fraction there were significant differences for the three metals while there was no significant difference at residual fraction.
  Khaled S.A. Said , M. Shuhaimi-Othman and A.K. Ahmad
  A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Ampang Hilir Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using Hydrolab Data Sonde 4® and Surveyor 4® a water quality multi probe (USA). Six metals which were cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Perkin Elmer Elan, model 9000.The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur.
  Khaled S.A. Said , M. Shuhaimi-Othman and A.K. Ahmad
  A study of water quality parameters (temperature, conductivity, total dissolved solid, dissolved oxygen, pH and water hardness) in Titiwangsa Lake was conducted in January, April, July and October 2010. The water quality parameters were tested and recorded at different sampling stations chosen randomly using hydrolab data sonde 4® and surveyor 4® a water quality multi probe (USA). Six metals i.e., cadmium, chromium, lead, nickel, zinc and copper were determined in five different compartments of the lake namely water, total suspended solids, plankton, sediment and fish. The metals concentration were determined by Inductively Coupled Plasma Mass Spectrometer (ICP-MS), perkin elmer elan, model 9000. The water quality parameters were compared with National Water Quality Standard (NWQS Malaysia) while metal concentrations were compared with Malaysian and international standards. The study shows that water quality parameters are of class 2. This condition is suitable for recreational activities where body contact is allowed and suitable for sensitive fishing activities. Furthermore, metal concentrations were found to be lower than the international standards, therefore toxic effects for these metals would be rarely observed and the adverse effects to aquatic organisms would not frequently occur.
  A.K. Ahmad , M.N.R. Nur-Hazwani , Sharifah Aisyah Syed Omar , E.R. Aweng and Abdulali Taweel
  Background and Objective: Malaysia reported experiencing serious invasive species intrusion in various rivers and threatening some local species to distinct. A study was undertaken to estimate and compare their composition and species richness in two pristine and two disturbed freshwater ecosystems. Materials and Methods: Invasive and local species growth pattern was also estimated using length-weight analysis. Sampling was conducted using cast net and electric shock in each river twice in 12 months. Fish collected were identified, photo captured and measured for their weight and length. The growth pattern was also estimated using length-weight analysis. Results: A total of 188 fishes were caught, comprises of 8 families and 15 species (ten local species with 119 individuals and five alien species with 69 individuals). Sistomus binotatus was the most dominant local species, whereas Tilapia nilotica was the most dominant alien species. There is no significant difference in composition between local and invasive species occur indicates the raise of alien species in those ecosystems even local species still dominated. The growth pattern for Sistomus binotatus and Clarias batrachus is isometric in the pristine ecosystem but negative isometric in disturbed rivers. Contrary, Tilapia nilotica has isometric for both ecosystems. Conclusion: This study concluded the capability and potential of colonization of alien species in stress ecosystem especially Tilapia nilotica. Thus, there is potential colonization of alien in Malaysia freshwater systems and a threat to local species due to food competition, site preferences and survival ability.
  M. Shuhaimi-Othman , Y. Nadzifah , N.S. Umirah and A.K. Ahmad
  Impact of metals to the environment is increasing problem worldwide. This study was conducted to determine the acute toxicity of 8 metals to worms Nais elinguis in laboratory. Adult freshwater worms N. elinguis (Oligochaeta, Naididae) were exposed for a four-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminum (Al) and manganese (Mn) concentrations. Mortality was assessed and median lethal times (LT50) and concentrations (LC50) were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively for all metals. Ninety-six hour LC50 for Cu, Cd, Zn, Pb, Ni, Fe, Al and Mn were 7, 27, 912, 580, 645, 123, 3874 and 364 μg L-1, respectively. Cu was the most toxic to N. elinguis followed by Cd, Fe, Mn, Pb, Ni, Zn and Al (Cu>Cd>Fe>Mn>Pb>Ni>Zn>Al). Comparison of LC50 values for metals for this species with those for other freshwater worms reveals that N. elinguis is equally or more sensitive to metals. This study indicates that N. elinguis is a potential organism in toxicity testing and as a bioindicator of metals pollution.
 
 
 
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