铁矿石中二氧化硅、全铁、磷的连续快速测定

对于铁矿石中铁的测定,通常选用经典的氯化亚锡还原,重铬酸钾滴定容量法。它具有简便、快速、准确、稳定等优点,适合于含铁量在0．5％以上的试样中铁的测定。     

新显色剂四-(3-磺基-4-氯苯基)卟啉分光光度法测定微量铜

研究了新显色剂四-(3-磺基-4-氯苯基)卟啉在微酸性介质中,表面活性剂OP与CPC存在下测定微量铜的显色反应。络合物在波长420 nm处有最大吸收峰,摩尔吸光度系数为3.44×105L·mol-1cm-1,用双峰双波长光度法测定摩尔吸光系数为6.72×105L·mol-1·cm-1,铜含量在0.5~4.5μg/25 m L范围内符合比耳定律。方法应用于矿样中微量铜的测定,结果令人满意。     

原子荧光法快速连续测定土壤样品中的砷锑铋汞硒

确定了各元素的最佳分析条件，可在王水介质中连续测定农业地质调查样品中的砷、锑、铋、汞、硒.该方法快速简便，分析结果与国家一级标样标准值相符合.     

浅述Z型采煤法工作原理及在汝州市的应用

目前,国内外地下采煤方法,主要分为三种类型：短壁式采煤法、前进式采煤法、后退式采煤法。本文就Ｚ型采煤法的工作原理及在汝州市庇山三矿的应用效果进行全面的对比分析。此采煤方法对促进煤炭企业实现四个效益的统一,延长矿井寿命,促进煤炭企业健康发展,变资源优势为经济优势都具有重大意义     

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.     

Assessment of point and nonpoint sources pollution in Songhua River Basin,Northeast China by using revised water quality model

Individual participation of pollutants in the pollution load should be estimated even if roughly for the appropriate environmental management of a river basin. It is difficult to identify the sources and to quantify the load, especially in modeling nonpoint source. In this study a revised model was established by integrating point and nonpoint sources into one-dimensional Streeter-Phelps (S-P) model on the basis of real-time hydrologic data and surface water quality monitoring data in the Jilin Reach of the Songhua River Basin. Chemical oxygen demand (COD) and ammonia nitrogen (NH_3-N) loads were estimated. Results showed that COD loads of point source and nonpoint source were 134 958 t/yr and 86 209 t/yr, accounting for 61.02% and 38.98% of total loads, respectively. NH_3-N loads of point source and nonpoint source were 16 739 t/yr and 14 272 t/yr, accounting for 53.98% and 46.02%, respectively. Point source pollution was stronger than nonpoint source pollution in the study area at present. The water quality of upstream was better than that of downstream of the rivers and cities. It is indispensable to treat industrial wastewater and municipal sewage out of point sources, to adopt the best management practices to control diffuse pollutants from agricultural land and urban surface runoff in improving water quality of the Songhua River Basin. The revised S-P model can be successfully used to identify pollution source and quantify point source and nonpoint source loads by calibrating and validating.     

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.     

In-situ determination of sediment oxygen demand in cultivation ponds

ＩＮＴＲＯＤＵＣＴＩＯＮＳｅｄｉｍｅｎｔｏｘｙｇｅｎｄｅｍａｎｄ(ＳＯＤ)ｉｎｃｌｕｄｅｓｂｉｏｌｏｇｉｃａｌａｎｄｃｈｅｍｉｃａｌｏｘｙｇｅｎｄｅｍａｎｄ(ＧｅｏｒｇｅａｎｄＪｏｓｅｐｈ,1980),ｉｓａｎｉｍｐｏｒｔａｎｔｆａｃｔｏｒａｆｆｅｃｔｉｎｇｄｉｓｓｏｌｖｅｄｏｘｙｇｅｎ(ＤＯ)ａｎｄｈａｓｂｅｃｏｍｅａｎｉｍｐｏｒｔａｎｔｐａｒａｍｅｔｅｒｉｎｍａｎｙｗａｔｅｒｑｕａｌｉｔｙｍｏｄｅｌｓｆｏｒｃｕｌｔｕｒｅｐｏｎｄｓ(Ｍａｄｅｎｊｉａｎ,1990;Ｆａｎｇ,1991).Ｓｏｉｔｉｓｎｅｃｅｓｓａｒｙｔｏ…     

考洲洋化学耗氧量(COD)的含量特征

1999年2月和8月对考洲洋海水、表层沉积物COD含量进行了调查研究.结果表明考洲洋海水COD含量为0.82～2.71 mg·L-1,表层沉积物COD含量为0.44～10.45 mg·L-1,其水质质量达到我国国家二类海水水质标准(COD＜3 mg·L-1).海水与表层沉积物COD含量平面分布总的呈西北部水域和湾中部水域向湾口降低的趋势.表层沉积物COD含量与有机质、硫化物含量呈显著的正相关(P＜0.05).与粤东邻近的网箱养殖水域比较,海水COD含量居中,表层沉积物COD含量较低.     

Environmental capacity of chemical oxygen demand in the Bohai Sea: modeling and calculation

A three-dimensional advection-diffusion model coupled with the degradation process is established for describing the transport of chemical oxygen demand (COD). Comparison of the simulated distribution of COD at the surface in the Bohai Sea in August, 2001 with field observations, shows that the model simulates the dataset reasonably well. The Laizhou Bay, Bohai Bay, and Liaodong Bay were contaminated heavily near shore. Based on the optimal discharge flux method, the Environmental Capacity (EC) and allocate...     

EVALUATION OF GEOCHEMICAL QUALITY CONTROL IN DETERMINATION OF Mn IN SOILS USING A SEQUENTIAL CHEMICAL EXTRACTION

Sequential chemical extraction procedure has been widely used to partition particulate trace metals into vari-ous fractions and to describe the distribution and the statue of trace metals in geo-environment.One sequential chemical extraction procedure was employed here to partition various fractions of Mn in soils.The experiment was designed with quality controlling concept in order to show sampling and analytical error.Experimental results obtained on duplicate analy-sis of all soil samples demonstrated that the precision was less than 10%(at 95% confidence level).The accuracy was estimated by comparing the accepted total concentration of Mn in standard reference materials (SRMs) with the measured sum of the individual fractions.The recovery of Mn from SRM1 and SRM2 was 94.1% and 98.4%,respectively.The detection limit,accuracy and precision of the sequential chemical extraction procedure were discussed in detailed.All the results suggest that the trueness of the analytical method is satisfactory.     

Spatial distribution and diurnal variation of chemical oxygen demand at the beginning of the rainy season in the Changjiang （Yangtze） River Estuary

A field observation was carried out in the Changjiang （Yangtze） River Estuary from May 19 to 26, 2003. A total of 29 stations, including 2 anchored stations, were occupied through almost the whole salinity gradient. Based on the observation data, biogeochemistry of chemical oxygen demand （COD） was examined. Spatial distribution pattern of COD shows that it decreased downstream. The COD concentration varied generally within a narrow range of 1.24-1.60 mg/L in the zone around the river mouth, beyond which it decreased rapidly to 0.20 mg/L. In the mixed water zone, the fluctuation in COD was smaller at 2 m above the bottom layer than at the surface layer in 48 h. In the seawater zone, the 48-h fluctuation at the surface was the largest, followed by that of 5 m below the surface and 2 m above the bottom layers in a range of from 2.50 to 0.55 mg/L. Freshwater discharge was the dominant source of COD in the estuary. The average COD beyond the river mouth was 2.7 mg/L, which accorded with the Chinese seawater quality Grade I. Relationships between dissolved oxygen and biogeochemical parameters such as suspended particulate matter, dissolved organic matter and chlorophyll-a were also discussed.     

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.     

Sodium and potassium in the bones of penguin and skua revealed by EPR and SR-XRF technique

Penguin and skua in the maritime Antarctic have high salt loadings in the body due to almost exclusive diet consumption of marine invertebrates. However, the storage and turnover of sodium and potassium in these animals are poorly investigated. Here we determined the concentration and microscopic distribution of the two elements in the bones of penguin and skua. The average concentrations of sodium and potassium in penguin bone were comparable with that in skua bone (0.18% and 0.82% for penguin bone; 0.19% and 0.76% for skua bone in dry weight). The ratios of sodium to calcium and potassium to calcium (0.0330 and 0.0075 for penguin, 0.0335 and 0.0082 for skua in average by weight) were somewhat higher than the reported ratios for terrestrial animals, indicating these marine animals' bone enrichment of salt. The ratios of sodium to potassium in average by weight were 6.75 and 4.65 for penguin and skua, respectively. This value is much lower compared with the bulk sea water ratio of about 27.0, implying that potassium is favorable to reside in the bone rather than sodium. Both sodium and potassium were found to significant correlation with the content of organic materials in bone based upon the intensity of native signal determined by electron paramagnetic resonance (EPR). It was estimated that almost all of potassium is kept within the organic phases, while about 30% of sodium is stored in organic phases and the other 70% within mineral phase. The microscopic distributions of potassium in the cross-section and/or surface were revealed by synchrotron radiation X-ray fluorescence (SR-XRF) technique. The ratio of potassium to calcium based upon the SR-XRF intensity counter varied considerably from the surface to the interior, and on the surface the highest concentration of potassium was observed in the middle section with decreasing amounts toward the edge. This indirectly documented that exchange of potassium between fluid and bone organic phase maybe occur.