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.     

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.     

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 PIP and POP in Seawater

1INTRODUCTIONInrecentyearsglobalclimatechangehasbeenanissueofbothpublicandscientificconcern.Oceanscover71 %ofearthandplayamajorroleinglobalclimatechange.Phosphorus,asacriticalelement,regulatespri maryproductioninaquaticecosystems.Therefore,thefunctionofphosphorusinoceansystemhasreceivedin creasingscientificinterest(Songetal.,2 0 0 3 ) .PP (particulatephosphorus)isanimportantforminphosphorustransferinseawater(Song,2 0 0 1 ) .Pro portionofPPintotalphosphorus(TP)inseawatervar iesfrom 1 0 …     

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.     

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.     

Determination of Trace Copper (Ⅱ) in Water Samples by Kinetic-spectrophotometry

A new kinetic-spectrophotometric method is proposed for the determination of copper ( Ⅱ ). The method is based on the catalytic effect of copper ( Ⅱ ) on the oxidation of weak acid brilliant blue dye (RAWL) by hydrogen peroxide. The copper ( Ⅱ ) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows: pH 7.20, buffer solution NaOH-KH2PO4, RAWL (200 mgL-1) 5.00 mL, H2O2 (30％) 0.50 mL, reaction temperature 80 ℃ and reaction time 20 min. The linear range of this method is between 0 μg L-1 and 12 μg L-1 and the limit of detection is 0.011 μg L-1, the relative standard deviation (RSD) in five replicate determinations for 2 and 8 μg L-1 copper ( Ⅱ ) are 3.2％ and 2.3％, respectively. Twenty ions do not interfere in the determination of copper ( Ⅱ ). The method has been applied satisfactorily to the determination of copper ( Ⅱ ) in freshwater samples (tap water and Yellow River water from Lijin, Shandong, China) and seawater samples (from the South China Sea), the recovery rates are 98.0％, 102.5％ and 96.0％, respectively.     

Determination of Trace Copper （Ⅱ） in Water Samples by Kinetic-spectrophotometry

A new kinetic-spectrophotometric method is proposed for the determination of copper （ Ⅱ ）. The method is based on the catalytic effect of copper （ Ⅱ ） on the oxidation of weak acid brilliant blue dye （RAWL） by hydrogen peroxide. The copper （ Ⅱ ） can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows： pH 7.20, buffer solution NaOH-KH2PO4, RAWL （200 mgL-1） 5.00 mL, H2O2 （30%） 0.50 mL, reaction temperature 80 ？？ and reaction time 20 min. The linear range of this method is between 0 μg L^-1 and 12 μg L^-1 and the limit of detection is 0.011 μg L-1, the relative standard deviation （RSD） in five replicate determinations for 2 and 8 μg L-1 copper （ Ⅱ ） are 3.2% and 2.3%, respectively. Twenty ions do not interfere in the determination of copper （ Ⅱ ）. The method has been applied satisfactorily to the determination of copper （ Ⅱ ） in freshwater samples （tap water and Yellow River water from Lijin, Shandong, China） and seawater samples （from the South China Sea）, the recovery rates are 98.0%, 102.5% and 96.0%, respectively.     

Optimization of sample pretreatment for determination of polycyclic aromatic hydrocarbons in estuarine sediments by gas chromatography

This study examined levels of polycyclic aromatic hydrocarbons (PAHs) in estuarine sediments in Licun (Qingdao, China) by gas chromatography under optimized conditions for sample pretreatment via ultrasonic extraction, column chromatography, and thin layer chromatography. Methanol and dichloromethane (DCM)/methanol (2:1, v/v) were used in ultrasonic extraction, and DCM was used as eluate for column chromatography. The developing system consisted of n-hexane and DCM at a ratio of 9:1 (v/v), with DCM as the extraction solvent for PAHs-containing silica gel scraped off the plate. When the spiking level is 100 ng, total recoveries of spiked matrices for four target PAHs (phenanthrene, anthracene, pyrene and chrysene) were 83.7%, 76.4%, 85.8%, and 88.7%, respectively, with relative standard deviation (RSD) between 5.0% and 6.5% (n = 4). When the spiking level is 1000 ng, associated total recoveries were 78.6%, 72.7%, 82.7% and 85.3%, respectively, with RSD between 4.4% and 5.3% (n = 4). The opti-mized method was advantageous for determination of PAHs in complex matrix due to its effective sample purification.     

新疆阿尔泰铁矿成矿流体及成矿过程

以新疆阿尔泰铁矿为研究对象,综述铁矿成矿背景,划分成因类型和成矿时期,对典型矿床地质特征进行描述,研究成矿流体的温度和盐度以及成矿流体来源,最后探讨构造演化与铁矿成矿作用。结果表明:铁矿成因类型可划分为火山岩型、矽卡岩型、伟晶岩型、与花岗岩有关的热液型、与基性岩体有关的钒钛磁铁矿型和砂矿型;矽卡岩矿床流体包裹体从矽卡岩阶段到退化蚀变阶段再到石英-硫化物-碳酸盐阶段的均一温度(从200℃～500℃到200℃～350℃,再到160℃～300℃)以及流体盐度(NaCleq)峰值(从4.5%～21.5%到3.5%～20.5%,再到1.5%～17.5%)逐渐降低;托莫尔特铁(锰)矿沉积期成矿流体以中低温(集中在160℃～300℃)、低盐度(主要集中在4%～9%和14%～20%)为特征;两棵树伟晶岩型铁矿成矿流体为中温(173℃～290℃)、低盐度(0.35%～16.05%);氢和氧同位素特征表明,火山沉积型铁矿沉积期成矿流体是海水与岩浆水的混合,矽卡岩阶段成矿流体主要为岩浆水,石英-硫化物-碳酸盐阶段成矿流体主要为大气降水,混合少量岩浆水,同时两棵树伟晶岩型铁矿成矿流体主要来源于岩浆水和大气降水的混合;碳和氧同位素表明,矽卡岩型铁矿成矿流体中碳主要来自深部岩浆,少量来自海相碳酸盐岩。     

海水养殖珍珠的染料染色研究

使用艳红S-BRL、艳黄S-5GL、枣红GRL、黑S-2R、红ST-3BF、黑ST-ED和黄ST-4RFN等7种染料,海水、去离子水、乙醇和甲醇等4种溶剂,以及Tween-80、十二烷基硫酸钠和聚乙二醇二甲醚等3种表面活性剂配成不同染液进行海水养殖珍珠染色。结果表明:使这7种染料达到最佳染色效果的溶剂和表面活性剂依次为去离子水和Tween-80、海水和十二烷基硫酸钠、去离子水和十二烷基硫酸钠、去离子水和Tween-80、海水和聚乙二醇二甲醚、海水和Tween-80、乙醇和聚乙二醇二甲醚。此外,艳黄S-5GL、红ST-3BF、黑ST-ED等以海水为溶剂的染色效果要优于以去离子水、乙醇和甲醇为溶剂的染色效果。中性染料着色效果好、孔口沾色轻,活性染料染色色彩鲜艳。     

An approach to determination of phenolic compounds in seawater using SPME-GC-MS based on SWCNTs coating

Phenolic compounds have become one kind of the important pollutants of the marine environment. Single-walled Carbon nanotubes, as one-dimensional nano materials, have light weight and perfect hexagonal structure of connections, with many unusual mechanical, chemical and electrical properties. In recent years, with the research of carbon nanotubes and other nano materials, the application prospect is also constantly discussed. In this paper, homemade single-walled carbon nanotubes(SWCNTs) coating was used for establishing an analytical approach to the determination of five kinds of phenolic compounds in seawater using SPME-GC-MS. Optimal conditions: After saturation was conducted with Na Cl, and p H was adjusted to 2.0 with H_2SO_4, the extract was immersed in a water bath at 40 for GC℃-MS determination through 40-min agitating extraction at 500 rmin~(-1) and 3-min desorption at 280℃. The liniearities ranged between 0.01-100 μg L~(-1), and the determination limits ranged between 1.5-10 ngL~(-1). The relative standard deviation(RSD, n = 5) was less than 6.5%. For the phenolic compounds obtained from the spiked recovery test for actual seawater samples, the rates of recovery were 87.5%-101.7%, and the RSDs were less than 8.8%, which met the requirements of determination. Due to its simplicity, high efficiency and low consumption, this approach is suitable for the analysis of trace amounts of phenolic compounds in marine waters.     

MARINE FOULING IN OFFSHORE AREAS EAST OF HAINAN ISLAND, NORTHERN SOUTH CHINA SEA

INTRODUCTIONBiofoulingonunderwaterpartsofman mademarinestructuresisamajoreconomicandtechni calproblemhavinginternationaldimensionsforthedevelopmentofoceanengineeringbecauseitnotonlyincreasesstaticandhydrodynamicloading,butalsoaffectscorrosioncharacteristicsandim pedesunderwaterinspectionandmaintenance (CallowandEdyvean ,1 990 ) .Duetodifferencesingeographicalpositionsandenvironmentalconditions,thedistributionofsessileorganismsvarieswitharea .Therefore ,understandingtheformationofbiofoulin…     

STATISTICAL PROPERTIES OF HIGH-FREQUENCY INTERNAL WAVES IN QINGDAO OFFSHORE AREA OF THE YELLOW SEA

Densely-sampled thermistor chain data obtained from a shallow-water acoustics experiment in the Yellow Sea off the coast of Qingdao were analyzed to examine the statistical properties of the 6 to 520 cpd frequency band internal waves observed. The negative skewness coefficients and the greaterthan-3 kurtosis coefficients indicated non-Gaussianity of the internal waves. The probability distributions were negatively skewed and abnormally high peaks. Nonlinear properties, as exemplified by the asymmetric waveshapes of the internal waves in the offshore area are described quantitatively.     

黄河三角洲地质资源环境承载力评价

黄河三角洲高效生态经济区的建立,将迎来大规模的基础建设和资源的消耗,从而加剧经济发展—资源消耗—环境污染之间的矛盾。黄河三角洲地区成陆时间较短,地质资源环境比较脆弱,淡水资源相对贫乏,近海地区生态保护及堤防修复压力较大。确定该区地质资源(水资源、土地资源)环境所能承受的人类各种社会经济活动的能力,并预测今后该区大规模人类活动可能对资源环境造成的影响。     

A New Spectrophotometric Method for Measuring COD of Seawater

This research studied a new spectrophotometric method for measuring the chemical oxygen demand （COD） of seawater. In this method, the COD was measured using a spectrophotometer instead of titrating with sodium thiosuiphate. The measuring wavelength was selected to be 470 nm, and the COD of three standard glucose solutions （COD = 0.5, 1.5 and 2.5 mgL^-1, respectively） and two seawater samples （from the South Yellow Sea and Jiaozhou Bay） were measured using the spectrophotometric method and titrimetric method respectively. The results showed that the spectrophotometric method was somewhat better than the titrimetric method. The relative standard deviation （RSD） of the spectrophotometric method was less than 2.7%, and the recovery of seawater samples ranged from 96.3% to 103.8%. In addition, the spectrophotometric method has other advantages such as expeditiousness, operation simplicity, analysis automatization, etc. Therefore the spectrophotometric method can be used to measure the COD of seawater with satisfactory results.     

Membrane preconcentration of iron in seawater samples and on-site determination in spectrophotometry

A novel method for on-site determination of trace iron was developed using membrane preconcentration and spectrophotometric detection. Fe(Ⅱ)-ferrozine complex was reacted with cetyltrimethylammonium bromide (CTAB) to form a Fe(Ⅱ)-ferrozine-CTAB paired compound, which was collected on a membrane by filtration under vacuum. The membrane was immersed in 2 mL of ethanol-nitric acid and the absorbance of the solution measured for quantitative analysis. Various factors affecting the iron collection and determination were investigated. With different sample preconcentration volumes, the range of determination was broadened to 0.5-120 g/L. The detection limit of this method reached 0.19 g/L and the recoveries were between 97.2 and 109% when the concentration enrichment was about 45. The relative standard deviation (n = 7) was 1.9% for samples containing 10 g/L Fe. Twelve seawater samples were analyzed on-site using the proposed method, and two were also analyzed in inductively coupled plasma mass spectrometry. No significant difference was shown between the two methods by the Student’s t-test. The method has also been used on-site for iron enrichment experiments with phytoplankton and concluded to be simple, accurate and inexpensive.     

ICP——AES测定金属元素铜活动态及其初步应用

金属元素活动态是我国5种深穿透地球化学技术中应用最广的方法之一。此方法是通过提取地表土壤一定深度介质中元素活动态的微弱隐伏矿信息而找寻隐伏矿,属于通过直接信息找矿,目前该方法的标准化程度不高。为将铜元素活动态应用于地质找矿,该文对铜元素4个活动态的相态(水浸出态、粘土吸附态、有机链合态、铁锰氧化物态)循序提取的条件及ICP-AES测定技术进行了研究,包括采样深度、分析样品粒度、样品存放时间、提取条件、测定干扰等,通过对铜活动态提取液处理方法的改进,提高了分析速度和分析数据的精度。由实验数据计算出各相态方法的检出限和精密度RSD(n=10),水浸出态为0.079mg/L,13.90%～22.49%;粘土吸附态为0.275mg/L,11.99%～23.29%;有机链合态为0.362mg/L,10.70%～57.27%;铁锰氧化物态为0.230mg/L,17.83%～38.61%。该方法操作方便,精密度较好,应用于碑楼隐伏铜矿的野外探测实验,探测结果所圈定的综合异常与实际矿体的水平投影相符,取得了较满意的试验效果,该方法可应用于不同地质景观区。     

The Influences of Mg~(2+), Ca~(2+) and Mg ~(2+)/Ca ~ (2+) Ratio in Mixed Seawater on the Emergence Rate of Penaeus japonicus Postlarva

ＩＮＴＲＯＤＵＣＴＩＯＮＰｅｎａｅｕｓｊａｐｏｎｉｃｕｓｉｓａｎｅｕｒｏｘｙｂｉｏｔｉｃｐｅｎａｅｉｄｐｒａｗｎ ,ｗｈｏｓｅｐｒｏｐｅｒｓａｌｉｎｉｔｙｒａｎｇｅｆｏｒｇｒｏｗｔｈｉｓ2 0 -30ａｎｄｏｐｔｉｍａｌｓａｌｉｎｉｔｙｒａｎｇｅｉｓ 2 5-30 (ＷａｎｇａｎｄＬｉｕ ,1 991 ;ＷａｎｇａｎｄＹｕ ,1 999) .Ｉｔｈａｓｇｒｅａｔｏｓｍｏｒｅｇｕｌａｔｉｏｒｙｃａｐａｃｉｔｙ (ＭａｎｔｅｌａｎｄＦａｍｅｒ,1 983) .Ｂｕｔｉｔｓｂｅｓｔｅｎｖｉｒｏｎｍｅｎｔｆｏｒｒｅｐｒｏｄｕｃｔｉｏｎａｎｄｄｅｖｅｌ…     

Chemical oxygen demand of seawater determined with a microwave heating method

This paper investigates a microwave heating method for the determination of chemical oxygen demand (COD) in seawater. The influences of microwave-power, heating time and standard substances on the results are studied. Using the proposed method, we analyzed the glucose standard solution, the coefficient of variation being less than 2%. Compared with the traditional electric stove heating method, the results of F-test and T-test showed that there was no significant difference between the two methods, but the microwave method had slightly higher precision and reproducibility than the electric stove method. With the microwave heating method, several seawater samples from Jiaozhou Bay and the South Yellow Sea were also analyzed. The recovery was between 97.5% and 104.3%. This new method has the advantages of shortening the heating time, improving the working efficiency and having simple operation and therefore can be used to analyze the COD in seawater.