A Kinetic Spectrophotometric Method for the Determination of Iron (Ⅲ) in Water Samples

A new kinetic spectrophotometric method has been developed for the determination of iron (Ⅲ). The method is based on the catalytic effect of iron (Ⅲ) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are: pH 3.15, RAWL (200 mgL-1) 5.00mL, Potassium periodate solution (0.01 molL-1) 0.30mL, phenanthroline (0.02molL-1) 1.00mL, reaction temperature 25℃ and reaction time 7 miu. With this method iron could quantitively be determined in the range 0.00-0.02 mgL-1, the detection limit being 4.10×10-10mL-1. The relative standard deviations (RSD) in five replicate determinations for 3 μgL-1 and 5μgL-1 iron (Ⅲ) are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron (Ⅲ) in tap water samples and seawater samples (from the South China Sea), the recovery rates being 98.0% and 100.5%, respectively.     

A Kinetic Spectrophotometric Method for the Determination of Iron （Ⅲ） in Water Samples

A new kinetic spectrophotometric method has been developed for the determination of iron (Ⅲ). The method is based on the catalytic effect of iron (Ⅲ) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are pH 3.15, RAWL (200 mgL-1) 5.00mL, Potassium periodate solution (0.01 molL-1) 0.30mL, phenanthroline (0.02molL-1) 1.00mL, reaction temperature 25℃ and reaction time 7 miu. With this method iron could quantitively be determined in the range 0.00-0.02 mgL-1, the detection limit being 4.10×10-10mL-1. The relative standard deviations (RSD) in five replicate determinations for 3 μgL-1 and 5μgL-1 iron (Ⅲ) are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron (Ⅲ) in tap water samples and seawater samples (from the South China Sea), the recovery rates being 98.0% and 100.5%, respectively.     

Mechanistic Study and Kinetic Determination of Cu(Ⅱ) by the Catalytic Kinetic Spectrophotometric Method

A highly sensitive and selective catalytic kinetic spectrophotometric method for the determination of Cu(Ⅱ) is proposed. It is based on the catalytic effect of Cu(Ⅱ) on the oxidation of glutathione(GSH) by potassium hexacyanoferrate(Ⅲ) in acidic medium at 25.0℃. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of oxidant at 420 nm using the fix-time method. Under the optimum conditions, the proposed method allows the determination of Cu(Ⅱ) in a range of 0-35.0 ng m L~(-1) with good precision and accuracy and the limit of detection is down to 0.04 ng m L~(-1). The relative standard deviation(RSD) is 1.02%. The reaction orders with respect to each reagent are found to be 1, 1/2, and 1/2 for potassium hexacyanoferrate(Ⅲ), glutathione and Cu(Ⅱ) respectively. On the basis of these values, the rate equation is obtained and the possible mechanism is established. Moreover, few anions and cations can interfere with the determination of Cu(Ⅱ). The new proposed method can be successfully used to the determination of Cu(Ⅱ) in fresh water samples and seawater samples. It is found that the proposed method has fairly good selectivity, high sensitivity, good repeatability, simplicity and rapidity.     

Study on the Determination of Trace Ni（Ⅱ） by the Catalytic Kinetic Spectrophotometric Method

A new kinetic spectrophotometric method has been developed for the determination of trace Ni (II) in natural water.The method is based on the catalytic effect of Ni (II) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium.The concentration of nickel (II) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ= 626 nm using the fix-time method.The influencing factors are investigated by the orthogonal experimental design.The obtained optimum analytical conditions are:pH=2.00,c RAWL=5.00×10-5 mol L-1,cKIO 4= 2.00×10-5 mol L-1,the reaction time t=10 min and the temperature T=25℃..Under the optimum conditions,the developed method allows the measurement of Ni (II) in a range of 0-40.0 ng mL-1.The standard deviation of eleven independent measurements of blank reaction is S=3.08×10-3 and the limit of detection is 2.20 ng mL-1.The relative standard deviations (RSDs) in six replicate determinations of 5 ng mL-1 and 8 ng mL-1 Ni (II) are 2.87% and 1.11%,respectively.Moreover,the experiments show few cations and anions can interfere with the measurement of Ni (II).The recovery efficiencies of this method are in a range of 97.0%-102.5% in freshwater samples.But there is a decreasing effect,which is about 0.2 times the added Ni (II) in seawater medium.After reasonable calibration this processing method is used for the determination of Ni (II) in seawater samples successfully.The results show this developed method has high accuracy and precision,high sensitivity,large range of linearity and high speed.The method can,therefore,be employed at room temperature.     

Determination of Trace Vanadium (Ⅴ) in Seawater and Fresh Water by the Catalytic Kinetic Spectrophotometric Method

A new kinetic spectrophotometric method has been developed for the determination of vanadium (Ⅴ).The method is based on the catalytic effect of vanadium (Ⅴ) on the oxidation of weak acid brilliant blue dye (RAWL) by KBrO3 using the citric acid as activation reagent.The obtained optimum conditions are:c (RAWL)=1×10-4 molL-1, c (KBrO3)=3×10-2 molL-1, c (citric acid)= 9×10-3 molL-1, pH=2.50, the reaction time being 7.0 min and the temperature being 25.0℃.Under the optimum conditions, the pro-posed method allows the determination of vanadium (Ⅴ) in the range of 0?70.0 ng mL-1 and the detection limit is down to 0.407 ng mL-1.For standard vanadium (Ⅴ) solution determination, the recovery efficiency is in the range of 98.5%?102% and the RSD ranges from 0.76%?1.25%.Moreover, it is demonstrated that most cations and anions do not interfere with the determination of vanadium (Ⅴ) under the analytical condition.The new method was successfully applied in the determination of vanadium (Ⅴ) in fresh water and seawater samples with satisfactory results.Vanadium (Ⅴ) in the seawater samples from Qingdao offshore was determined using the method and the distribution of vanadium (Ⅴ) was mapped.Compared with other instrumental analytical methods, the proposed method shows good selectivity, sensitivity, simplicity, lower cost and rapidity.It can be employed on shipboard easily.     

Measurement of Trace Manganese(Ⅱ) by the Catalytic Kinetic Spectrophotometric Method

A new kinetic spectrophotometric method is developed for the measurement of manganese (Ⅱ) in water. The method is based on the catalytic effect of manganese (Ⅱ) with the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 using the Nitrilo triacetic acid (NTA) as an activation reagent. The optimum conditions obtained are 40mgL-1 RAWL, 1×10-4molL-1 KIO4, 2×10-4molL-1 Nitrilo triacetic acid (NTA), pH = 5.8, the reaction time of 3.00 min and the temperature of 20.0 ℃. Under the optimum con-ditions, the proposed method allows the measurement of manganese (Ⅱ) in a range of 0-50.0ngmL-1 and with a detection limit of down to 0.158 ng mL-1. The recovery efficiency in measuring the standard manganese (Ⅱ) solution is in a range of 98.5%-102%, and the RSD is in a range of 0.76%-1.25%. The new method has been successfully applied to the measurement of manganese (Ⅱ) in both fresh water and seawater samples with satisfying results. Moreover, few cations and anions interfere with the measurement of man-ganese (Ⅱ). Compared with other kinetic catalytic methods and instrumental methods, the proposed method shows fairly good selec-tivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can be applied on boats easily.     

Simultaneous determination of calcium and magnesium in water using artificial neural network spectro-photometric method

A new analytical method using Back-Propagation(BP) artificial neural networks and spectrophotometry for simultaneous determination of calcium and magnesium in tap water,the Yellow River water and seawater is established.By condition experiment,the optimum analytical conditions for calcium,magnesium and Arsenazo(Ⅲ) color reactions are obtained.Levenberg-Marquart(L-M) algorithm is used for calculation in BP neural network.The topological structure of three-layer BP ANN network architecture is chosen as 11-10-2(nodes).The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of μ take the default values of the system.The data are processed by computers with our own programs written in MATLAB 7.0.The relative standard deviations of the calculated results for calcium and magnesium are 2.31% and 2.14%,respectively.The results of standard addition method show that the recoveries of calcium and magnesium are 103.6% and 100.8% in the tap water,103.2% and 96.6% in the Yellow River water(Lijin district of Shandong Province),and 98.8%-103.3% and 98.43%-103.4% in seawater from Jiaozhou Bay of Qingdao.It is found that 14 common cations and anions do not interfere with the determination of calcium and magnesium under the optimum experimental conditions.The comparative experiments do not show any obvious difference between the results obtained by this new method and those obtained by the classical complexometric titration method in seawater medium.This method exhibits good reproducibility and high accuracy in the determination of calcium and magnesium and can be used for the simultaneous determination of Ca2+ and Mg2+ in tap water and natural water.     

Simultaneous determination of iron and manganese in water using artificial neural network catalytic spectrophotometric method

A new analytical method using Back-Propagation (BP) artificial neural network and kinetic spectrophotometry for simultaneous determination of iron and magnesium in tap water, the Yellow River water and seawater is established. By conditional experiments, the optimum analytical conditions and parameters are obtained. Levenberg-Marquart (L-M) algorithm is used for calculation in BP neural network. The topological structure of three-layer BP ANN network architecture is chosen as 15-16-2 (nodes). The initial value of gradient coefficient μ is fixed at 0.001 and the increase factor and reduction factor of μ take the default values of the system. The data are processed by computers with our own programs written in MATLAB 7.0. The relative standard deviation of the calculated results for iron and manganese is 2.30% and 2.67% respectively. The results of standard addition method show that for the tap water, the recoveries of iron and manganese are in the ranges of 98.0%-104.3% and 96.5%-104.5%, and the RSD is in the range of 0.23%-0.98%; for the Yellow River water (Lijin district of Shandong Province), the recoveries of iron and manganese are in the ranges of 96.0%-101.0% and 98.7%-104.2%, and the RSD is in the range of 0.13%-2.52%; for the seawater in Qingdao offshore, the recoveries of iron and manganese are in the ranges of 95.3%-104.8% and 95.3%-104.7%, and the RSD is in the range of 0.14%-2.66%. It is found that 21 common cations and anions do not interfere with the determination of iron and manganese under the optimum experimental conditions. This method exhibits good reproducibility and high accuracy in the determination of iron and manganese and can be used for the simultaneous determination of iron and manganese in tap water and natural water. By using the established ANN- catalytic spectrophotometric method, the iron and manganese concentrations of the surface seawater at 11 sites in Qingdao offshore are determined and the level distribution maps of iron and manganese are drawn.     

Size-fractionated phytoplankton biomass in autumn of the Changjiang （Yangtze） River Estuary and its adjacent waters after the Three Gorges Dam construction

A cruise was undertaken from 3rd to 8th November 2004 in Changjiang （Yangtze） River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll-a （Chl-a） concentration ranged 0.42-1.17 μg L^-1 and 0.41-10.43 μg L^-1 inside and outside the river mouth, with the mean value 0.73 μg L^-1 and 1.86 μg L^-1, respectively. Compared with the Chl-a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl-a was 10.43 μg L^-1 at station 18 （122.67°E, 31.25°N）, and the region of high Chl-a concentration was observed in the central survey area between 122.5°E and 123.0°E. In the stations located east of 122.5°E, Chl-a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl-a in sizes of 〉20 μm and 〈20 μm was 0.28 μg L^-1 and 1.40 μg L^-1, respectively. High Chl-a concentration of 〈20 μm size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl-a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.     

Engineering geological characteristics of slide zone soil and stability for one landslide in Tibet

On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical properties for the soil in the slide zone.The soil samples are gravel containing fine particle.Particles larger than 2 mm occupy the main proportion with the content 51.5%--68.5%.The relative content of clay minerals is low.The clay minerals are illite smectite mixed layer and kaolinite,and their relative contents are 6%--13% and 4%-11%,respectively.The main mineral ingredient is quartz and the relative content is over 30%.Therefore,the soil’s hydrophily is poor.The cohesion and internal friction angle are high,causing preferable physical-mechanical features of slide zone soil.On the basis of the obtained data,the landslide stability is evaluated by means of limit equilibrium method.The safety factors are 3.191 and 1.92 respectively under both natural and normal water level conditions.The study results show that the landslide is stable.It can provide the appropriate basis and reference for landslide stability evaluation and landslide control in Tibet.     

Measurement of trace manganese (II) by the catalytic kinetic spectrophotometric method

A new kinetic spectrophotometric method is developed for the measurement of manganese (II) in water. The method is based on the catalytic effect of manganese (II) with the oxidation of weak acid brilliant blue dye (RAWL) by KIO₄ using the Nitrilo triacetic acid (NTA) as an activation reagent. The optimum conditions obtained are 40 mgL⁻¹ RAWL, 1×10⁻⁴molL⁻¹ KIO₄, 2×10⁻⁴ molL⁻¹ Nitrilo triacetic acid (NTA), pH = 5.8, the reaction time of 3.00 min and the temperature of 20.0 °C. Under the optimum conditions, the proposed method allows the measurement of manganese (II) in a range of 0–50.0 ng mL⁻¹ and with a detection limit of down to 0.158 ng mL⁻¹. The recovery efficiency in measuring the standard manganese (II) solution is in a range of 98.5%–102%, and the RSD is in a range of 0.76%–1.25%. The new method has been successfully applied to the measurement of manganese (II) in both fresh water and seawater samples with satisfying results. Moreover, few cations and anions interfere with the measurement of manganese (II). Compared with other kinetic catalytic methods and instrumental methods, the proposed method shows fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can be applied on boats easily.     

Bioflocculant Produced by Klebsiella sp. MYC and Its Application in the li＇eatment of Oil-field Produced Water

Seventy-nine strains of bioflocculant-producing bacteria were isolated from 3 activated sludge samples. Among them, strain MYC was found to have the highest and stable flocculating rate for both kaolin clay suspension and oil-field produced water. The bacterial strain was identified as Klebsiella sp. MYC according to its morphological and biochemical characteristics and 16SrDNA sequence. The optimal medium for bioflocculant production by this bacterial strain was composed of cane sugar 20 g L^-1, KH2PO4 2 g L^-1, K2HPO4 5 g L^- 1, （ NH4）2SO4 0.2 g L^-1, urea 0.5 g L^- 1 and yeast extract 0.5 g L^- 1, the initial pH being 5.5. When the suspension of kaolin clay was treated with0.5% of Klebsiella sp. MYC culture broth, the flocculating rate reached more than 90.0% in the presence of 500mg L^-1 CaCI2, while the flocculating rate for oil-field produced water was near 80.0% in a pH range of 7.0 - 9.0 with the separation of oil and suspended particles from the oil-field produced water under similar conditions. The environment-friendly nature of the bioflocculant and high flocculating rate of the strain make the bioflocculant produced by Klebsiella sp. MYC an attractive bioflocculant in oil-field produced water treatment.     

Determination of trace vanadium (V) in seawater and fresh water by the catalytic kinetic spectrophotometric method

A new kinetic spectrophotometric method has been developed for the determination of vanadium (V). The method is based on the catalytic effect of vanadium (V) on the oxidation of weak acid brilliant blue dye (RAWL) by KBrO₃ using the citric acid as activation reagent. The obtained optimum conditions are: c (RAWL) = 1×10⁻⁴ molL⁻¹, c (KBrO₃) = 3×10⁻² molL⁻¹, c (citric acid) = 9×10⁻³ molL⁻¹, pH = 2.50, the reaction time being 7.0 min and the temperature being 25.0°C. Under the optimum conditions, the proposed method allows the determination of vanadium (V) in the range of 0–70.0 ng mL⁻¹ and the detection limit is down to 0.407 ng mL⁻¹. For standard vanadium (V) solution determination, the recovery efficiency is in the range of 98.5%–102% and the RSD ranges from 0.76%–1.25%. Moreover, it is demonstrated that most cations and anions do not interfere with the determination of vanadium (V) under the analytical condition. The new method was successfully applied in the determination of vanadium (V) in fresh water and seawater samples with satisfactory results. Vanadium (V) in the seawater samples from Qingdao offshore was determined using the method and the distribution of vanadium (V) was mapped. Compared with other instrumental analytical methods, the proposed method shows good selectivity, sensitivity, simplicity, lower cost and rapidity. It can be employed on shipboard easily.     

Immunotoxicity effect of benzo[α]pyrene on scallop Chlamys farreri

The toxic effects of benzo[α]pyrene (B[α]P) at different concentrations (0.1, 0.5, 1, 2.5 and 7.5 μgL⁻¹) on scallop (Chlamy farreri) immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity (P<0.05), while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL⁻¹ B[α]P decreased significantly (P<0.05). Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]P. Bacteriolytic activity in 0.1μgL⁻¹ B[α]P treatment group and antibacterial activity in 0.1 μgL⁻¹ and 0.5 μgL- B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group (P<0.05), except for antibacterial activity in 0.1 μgL⁻¹ B[α]P treatment group (P>0.05). Thus, B[α] has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms.     

Effects of nutritional factors on the growth and heterotrophic eicosapentaenoic acid production of diatom <Emphasis Type="Italic">Nitzschia laevis</Emphasis>

The effects of several nutritional factors on the growth and eicosapentaenoic acid (EPA) production of diatom Nitzschia laevis were studied. 4 LDM (quadrupled concentration of the nutrient salt) was the optimal concentration of nutrient salt for the growth and EPA production of N. laevis. The growth of N. laevis was inhibited when the glucose concentration was either lower than 10 gL⁻¹ or higher than 15 gL⁻¹. Both sodium nitrate and urea were good nitrogen sources for the growth and EPA production, while ammonium chloride seriously decreased the dry cell weight (DW) and the EPA content. Silicate seriously influenced the growth of N. laevis. The maximum DW of 2.34 gL⁻¹ was obtained in the presence of 150 mgL⁻¹ Na₂SiO₃·9H₂O. The EPA content remained almost the same when the silicate concentration was lower than 150 mgL⁻¹; however, higher silicate concentrations resulted in a steady decrease of EPA content. Low medium salinity (⩽29) did not seem to influence the DW of N. laevis, and high salinity resulted in a decrease of DW. The highest EPA content (4.08%) and yield (110 mgL⁻¹) were observed at the salinity of 36 and 29, respectively.     

Determination of Selenium in Marine Aquatic Products by Hydride Generation-atomic Fluorescence Spectrometry （HG-AFS）

A method for the analysis of selenium in marine aquatic products by HG-AFS has been investigated. The method is based on the reduction of inorganic selenium to volatile SeH2 which is bubbled out by carrier gas of pure argon, and then swept to Ar-H2 flame quarts atomizer to measure its fluorescence intensity. The hydride generation, transportation, atomization and some instrumental parameters were studied by a kind of orthogonal design. The optimum conditions selected are as follows： reactive acidity, 20% HC1; the amount of NaBH4, 4.9mL; gas flow of argon, 600mLmin^-1; atomizing temperature, 200 ℃ ; negative high voltage, - 300V; light current, 100 mA; integral time, 7s. The detection limit of the presented method is 0.072μgL^-1 for selenium. The calibration curve shows a satisfactory line inthe concentration range from 0.000 to 1.000μgL^-1 Se. The recovery is 95.8%-102.2%.     

Biosorption of Cd (Ⅱ) and Pb (Ⅱ) Ions by Aqueous Solutions of Novel Alkalophillic Streptomyces VITSVK5 spp. Biomass

Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. The search of marine actinobacteria with potential heavy metal biosorption ability resulted in the identification of a novel alkalophilic Streptomyces VITSVK5 species. The biosorption property of Streptomyces VITSVK5 spp. was investigated by absorbing heavy metals Cadmium (Cd) and Lead (Pb). Physiochemical characteristics and trace metal concentration analysis of the backwater showed the concentrations of different metals were lead 13±2.1 μg L⁻¹, cadmium 3.1±0.3μg L⁻¹, zinc 8.4±2.6μg L⁻¹ and copper 0.3±0.1μg L⁻¹, whereas mercury was well below the detection limit. The effect of pH and biomass dosage on removal efficiency of heavy metal ions was also investigated. The optimum pH for maximal biosorption was 4.0 for Cd (II) and 5.0 for Pb (II) with 41% and 84% biosorption respectively. The biosorbent dosage was optimized as 3 g L-1 for both the trace metals. Fourier transform infrared absorption spectrum results indicated the chemical interactions of hydrogen atoms in carboxyl (-COOH), hydroxyl (-CHOH) and amine (-NH₂) groups of biomass with the metal ions. This could be mainly involved in the biosorption of Cd (II) and Pb (II) onto Streptomyces VITSVK5 spp. The results of our study revealed Streptomyces metabolites could be used to develop a biosorbent for adsorbing metal ions from aqueous environments.     

Exopolysaccharide Production by Four Cyanobacterial Isolates and Preliminary Identification of These Isolates

Four marine cyanobacterial isolates, named 104, 109, 113 and 115, from marine water off China＇s coast can release a large amount of exopolysaccharide （EPS） to medium. The effects of different components in medium on EPS production by the four isolates were investigated. Under the optimal condition, the EPS released by isolates 104,109, 113 and 115 reached 7.48 g L^-1, 8.33 g L^-1, 18.26 g L^-1, and 6.78 g L^-1 within 14 d,respectively. Based on the conventional identification methods for cyanobacteria,these isolates were assigned to genus Cyanothece.