Volume 2 Number 1 2008

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CONTENTS AND ABSTRACTS

Ahmed Abdel-Megeed (Saudi Arabia), Fatma Aly El-Nakieb (Egypt) Bioremediation of Dimethoate by Effective Microorganisms in Water (pp 1-4)

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Original Research Paper: A unique approach for the degradation of organophosphorus pesticide dimethoate in aqueous media with effective, microorganisms (EM) was investigated. These microbial consortia could tolerate up to about 120 mg L⁻¹ of dimethoate (technical grade). Several factors influencing dimethoate degradation were investigated. The growth rate µ (h^-1) of these effective microorganisms was ca. 0.925. The acetonitrile extracts of EM cultures were subjected to gas liquid chromatography (GLC) using two different solvent systems: hexane–chloroform–methanol and cyclohexane–acetone–chloroform. GLC analyses revealed the complete degradation and disappearance of dimethoate after 3 days. However, the precise conditions for this pesticide degradation were not fully understood. A change in pH of the culture medium to an acidic range supported the biological transformation of the compound. Optimal growth conditions were pH 8.5 and 27°C. Two isolates from these microbial consortia lost their ability to utilize dimethoate. The intermediate compounds were also metabolized, further resulting in complete mineralization of dimethoate. Thus, the present study establishes the EM degradation of dimethoate and also suggests their role in the bioremediation of other pesticide-contaminated water.

Foluso Oyedotun Agunbiade, Bamidele Iromidayo Olu-Owolabi, Kayode Oyebode Adebowale (Nigeria) Empirical Modelling of Dissolved Oxygen against Pollution Parameters in Coastal Water in Different Seasons (pp 5-13)

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Original Research Paper: An empirical modelling study of dissolved oxygen (DO) against six pollution parameters: biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, total phosphate, total solids and temperature, analysed from field samples was carried out for wet and dry seasons of April 2006 – January 2007. Modelled equations were developed from each parameter using regression analysis to predict DO within the two seasons; the best fitted equation was reported in each case with their corresponding R² values and the validity ranges evaluated for model calibration. The resulting DO values predicted from the modelled equations were validated by comparison with field data and found to correlate better in the dry season for data obtained based on BOD, COD, nitrate and phosphate. Also, the validity ranges of the models developed from these anthropogenic pollution parameters were wider during the dry season. However, total solids (TS) and temperature used to measure contributions from physical and natural conditions to DO modelling depicts a better simulation during the wet season for the TS prediction due to an increase in natural effects witnessed in the wet season than the dry one. Temperature had the lowest R² values due to reduced natural temperature variations in the tropical region. Thus, the predictions of DO based on anthropogenic, abstracting pollution parameters are better done in the dry season.

Rajni Bala, Ashwani K. Thukral (India) Interactions between Chromium and Plant Growth Regulators on the Growth of Spirodela polyrrhiza (L.) Schleiden (pp 14-18)

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Original Research Paper: Chromium is one of the most toxic heavy metals which reduces the growth of plants at relatively low concentrations, whereas IAA, kinetin, GA₃ and 24-epibrassinolide (24-epiBr) are well known plant growth regulators (PGRs) which enhance the growth of plants. The present study was undertaken to determine the effect of binary combinations of Cr(VI) and PGRs on Spirodela polyrrhiza (L.) Schleiden, an aquatic macrophyte, grown on Hoagland’s E-media. We observed that Cr(VI) at 1, 2 and 3 mM in the absence of exogenous PGRs significantly decreased the growth of plants, whereas IAA, kinetin, GA₃ (0.1, 10, 1000 nM) and 24-epiBr (0.01, 1, 100 nM) in the absence of Cr(VI) significantly increased the growth. Multiple regression models revealed that Cr(VI) inhibits the activity of exogenous PGRs leading to a further decrease in the growth of S. polyrrhiza cultured in binary combinations of Cr(VI) and PGRs.

Dmitrij I. Bashmakov, Marina V. Tserkovnova, Alexander S. Lukatkin (Russia), Jaime A. Teixeira da Silva (Japan) Variability in Heavy Metal Tolerance between Saransk (Russian) Taraxacum officinale Populations (pp 19-24)

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Original Research Paper: Dandelion (Taraxacum officinale Wigg.) plants growing wild in Saransk City and its precincts were the subject of this investigation. Initially the heavy metal (HM) concentration of 8-10 individuals from four ecological zones (equivalent to 10 ecotopes) was measured and an index of biological accumulation was determined. Growth responses of dandelion seedlings to various HMs at several concentrations were assessed in in vitro bioassays. Seeds (100-200) from plants in the exact same locations were collected and stimulated to germinate on modified Knop medium with different concentrations of four HMs (Ni²⁺, Pb²⁺, Zn²⁺ or Cu²⁺). HM-tolerant dandelion ecotypes were identified from several of the HM-contaminated sites. These ecotypes differed in their magnitude of tolerance, which depended on the concentration of the heavy metal in the growth medium and could be grouped into two edaphotypes: those from industrial and habitation zones, the phytostabilizators (concentrate and keep HMs in roots) and those from suburban zones, the phytoextractors (concentrate HMs in aboveground organs). Dandelion was considered an Fe-hyperaccumulator in all ecotopes.

Folasegun A. Dawodu, Kolawole O. Ajanaku (Nigeria) Evaluation of the Effects of Brewery Effluents Disposal on Public Water Bodies in Nigeria (pp 25-29)

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Original Research Paper: Investigation of the effect of brewery industries effluents disposal on their surrounding surface and ground waters were carried out. Four brewery industries at different locations in Benin, Ibadan and Lagos were selected for the study. The water samples were subjected to laboratory analysis to determine variation in physical, chemical and elemental components of the samples. The results of the groundwater parameters examined tended to fall within the Federal Ministry of Environment and Urban Development (FMEUD) and World Heath Organization (WHO) recommended standard values. The results of the surface waters when compared with National (FMEUD) and International (WHO) permissible limits for aquatic ecosystems indicated that the physicochemical condition of the streams located at Agidingbi, Alaka, Ona and Ossioma have been influenced by the various pollutants.

Stephen S. Hati, Goni A. Dimari, Maimuna Waziri, Yahaya N. Pindiga (Nigeria) Interaction Profile for As, Cd, Cr and Pb in Surface Water, Superficial Sediments and Background Sediments of Lake Alau, Maiduguri, Nigeria (pp 30-33)

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Original Research Paper: The interaction profiles for the quaternary heavy metals (As, Cd, Cr and Pb) was investigated in the aquatic media, surface water (SW), superficial sediments (SS, 0-1cm), and background sediments (BS, 20-30 cm) of Lake Alau, Nigeria. SW samples were digested with HNO₃ and sediment samples extracted with 1 M solution of ammonium acetate (NH₄OAc) in a 1:10 weight ratio and analysed by standard calibration methods of flame atomic absorption spectrophotometry. The results show that Cr was found in the highest concentration in all media and the order of concentration in SW was Cr > Cd > As > Pb and Cr > Pb > As > Cd in SS and BS. The inter-metal correlation coefficient (r) values revealed the highest negative correlation values (r= -0.95; -0.92) between Cd and Cr in BS for both wet and dry seasons. Seasonal variations imparted dilution effects which was not statistically significant. However, the metal concentrations are within limits suitable for irrigation and drinking water though with possible long term health implications.

Saeed Minoui, Dariush Minai-Tehrani, Amanallah Zare, Shiva Ahmadi (Iran) Effect of Heavy Crude Oil on the Pattern of Respiratory Chain of Pseudomonas sp. (pp 34-37)

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Original Research Paper: Bacteria are versatile organisms which can grow in different mediums. The respiratory chain of bacteria consists of different cytochromes and terminal oxidases, which allow their adaptation to various media. Pseudomonas is a useful bacterium for industries, it can aerobically biodegrade some types of toxic materials in soil and water. One of the most important organic pollutants in oil-producing countries is crude oil. Pseudomonas is able to biodegrade crude oil and use it as a carbon source. Our results show that Pseudomonas can degrade aliphatic fractions of crude oil more efficiently than aromatic fractions. Pseudomonas uses the cytochrome bo complex as its main terminal oxidase in nutrients rich medium and in medium containing ethanol as carbon source, while in medium containing crude oil, it uses both cytochrome bo and bd complexes as terminal oxidase.

Friday Onyekwere Nwosu, Bamidele Iromidayo Olu-Owolabi, Kayode Oyebode Adebowale, Luter Leke (Nigeria) Comparative Investigation of Wear Metals in Virgin and Used Lubricant Oils (pp 38-43)

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Original Research Paper: Four samples of virgin lubricating oils were categorized as A1, B1, C1 and D1 while their used oil counterparts were designated as A2, B2, C2 and D2 respectively. A dry ash method was adopted for digestion of the samples in a 1:1 ratio (w/v) of oil: concentrated H₂SO₄ followed by dissolution with 2 M HNO₃ acid. The digested samples were separately subjected to flame atomic photometry analysis for alkali and alkaline earth metals while other metals were subjected to atomic absorption spectrometric analysis. The specific densities of the virgin oils fell within the range of 0.941–0.952 while their corresponding used oil values ranged between 0.923 and 0.932. The viscosity value ranges obtained were 72.77–79.27 cp for virgin oil and 64.27–79.27 cp for used oil. The wear metal concentrations determined for virgin oil were in the range of 110–150, 17–1957, 5.0–53.3, 1.1–1.7, 3.2–14.1, 2.7–5.2, 1.5–5.4, 45.13–106.8, 46.1–61.0 mg/kg for Na, Mg, Pb, Cd, Cr, Cu, Fe, Zn and Mn, respectively. Their corresponding used oil metal concentrations were in the range of 99–193, 72–2567, 150–810, 1.1–20.3, 5.1–754, 2.4–5.13, 3.2–6.2, 13.0–73.6 and 30.6–50.7 mg/kg respectively for the same metal ions. Among the investigated metal ions of C2, Pb made up 20.63% while Cr made up 56.53% of B2. The information about these metal concentrations will be helpful in monitoring and maintaining vehicles and machine engines while also indicating which metals could be quantitatively recovered and thereby being used to solve environmental problems.

Nnenna E. Okoronkwo, Jude C. Igwe, Hope N. Uruakpa (Nigeria) Dye Removal from Waste Water by Adsorption onto Boiler Fly Ash (pp 44-48)

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Original Research Paper: The treatment of wastewater is essential not only to achieve an environment devoid of pollution but also to meet up with the water needs of the community. Dyes have been in use mainly in the textile industry for dyeing fabrics. This introduces dyes and dye products into the effluent water, which must be removed for water re-use and recycling and also for environmental pollution control. The use of waste boiler fly ash derived from a palm oil mill for the adsorptive removal of methyl orange and Congo red was studied in this paper. As time increased, the amount of dye removed increased to a maximum at 20 minutes for methyl orange (249.9 mg/L) and 60 minutes for Congo red (249.999 mg/L) and later decreased to 249.83 mg/L at 60 minutes for methyl orange and 249.99 mg/L at 120 minutes for Congo red. Therefore, Congo red was adsorbed more than methyl orange. The sorption process was modeled using Langmuir and Freundlich isotherm models. The Freundlich isotherm gave a better fit than the Langmuir isotherm although both did not give an excellent correlation. The experiment was also modeled using pseudo-first and pseudo-second order equations. The pseudo-second order gave a better fit with an R² value of 1.00 for both dyes. The rate constant K₂ was found to be 1.6 g mg^-1 min^-1. This means that waste boiler fly ash could be used as an excellent adsorbent for removal of Congo red and methyl orange from waste water.

Nnenna E. Okoronkwo, Jude C. Igwe, Hobby I. Ogbonna (Nigeria) Detoxification of Hg²⁺, Cd²⁺ and Fe²⁺ from Aqueous Solution using Waste Boiler Fly Ash (pp 49-53)

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Original Research Paper: Heavy metal pollution is one of the main problems for the ecosystem due to technological development. The pollution and toxicity problems posed by heavy metals in the environment have long been established. Efforts to minimize production of hazardous waste and to remediate existing accumulated waste have become one of the most important environmental challenges that the world faces today. The detoxification of Hg (II), Cd (II) and Fe (II) from aqueous solution using boiler fly ash was studied. The amount of the metal ions adsorbed increased as the initial concentration of the metal was increased. The sorption process was very rapid reaching equilibrium at about 20 minutes for the three metal ions. The trend of the sorption is Cd (II) > Fe (II) > Hg (II). The sorption process was modeled using the pseudo-first and pseudo-second order equations with the later giving a better fit with R² values of Hg (II) (0.9967), Cd (II) (0.9947) and Fe (II) (0.9837). The pseudo-second order rate constants for the metal ions were 13.46 for Cd (II), and 7.22 for Fe (II) and 7.78 x 10^-4 for Hg (II), all in mg g^-1min^-1, which confirms the trend of the sorption. Therefore, boiler fly ash which is a waste from palm oil mills could be used as an effective adsorbent for the removal of heavy metals from waste water.

Luke N. Ukiwe, Emeka E. Oguzie (Nigeria) Effect of pH and Acid on Heavy Metal Solubilization of Domestic Sewage Sludge (pp 54-58)

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Original Research Paper: Heavy metal removal from domestic sewage was solubilized using HCl, HNO₃, and H₂SO₄ at pH 1.0, 2.0, 3.0, and 4.0. Results of analysis of digested samples analyzed with Atomic Absorption Spectrophotometer showed that selenium (1030.9159, 1043.3573, 1097.0605, 1097.9538 mg/l) was the highest metal solubilized at pH 1.0, 2.0, 3.0 and 4.0, respectively while nickel (0.0000, 0.3560, 0.0000, 0.2002 mg/l) was the least solubilized metal at the same pH levels using H₂SO₄, which was also observed to be the most suitable acid for solubilization of metals. In the absence of complexing ligands as in the male sewage sample, solubilization of metal was highest at low pH levels.