A comparison between high temperature catalytic and persulfate oxidation for the determination of total dissolved nitrogen in natural waters

Total dissolved nitrogen(TDN) is an important parameter for assessing the nutrient cycling and status of natural waters.The accurate determination of TDN in natural waters is essential for assessing its contents and distinguishing different forms of nitrogen in the water.The TDN in various systems has been largely documented,and the concentrations of TDN are usually obtained using high-temperature catalytic(HTC) or persulfate oxidation(PO).However,the accuracy of these methods and their suitability for all types of natural waters are still unclear.To explore both methods in-depth,assorted samples were tested,including eight solutions composed of nitrogen-containing compounds(3 dissolved inorganic nitrogen fractions:NO_(3)^(-),NO_(2)^(-)and NH_(4)^(+);5 organic compounds:EDTA-2Na,vitamin B1,vitamin B12,amino acids,and urea) and 105 natural waters which were collected from an open ocean(Northwest Pacific Ocean,28),a marginal sea(Yellow Sea,34),an estuary(Huanghe River mouth,31),rivers(Huanghe River,4;Licun River,4),and precipitations(4 samples).The results showed that heterocycles and molecular dimensions had certain effects on the oxidation efficiency of the PO method but had little effect on HTC.There was no significant difference between the two methods for natural waters,but HTC was more suitable for deep-sea samples with low TDN concentrations(less than 10 μmol/L) and low organic activity.Overall,HTC has a relatively simple measurement process,a high degree of automation,and low error.Therefore,HTC can be recommended to determine the TDN of samples in freshwater and seawater.

Comparison of Pb,Cd Adsorption to Surface Coatings Developed in Natural Waters with that in Plant Effluents

The comparative studies of Pb and Cd adsorption to the surface coatings(Fe, Mn, Al oxides, organic materials, and associated minerals), which were developed on glass slides in five natural and two technical waters(plant effluents), were carried out under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25 ℃ and pH 6 0). The classical Langmuir adsorption isotherm was applied to estimating the equilibrium coefficients of Pb and Cd adsorption to the surface coatings. The results show that the maximum adsorption of Pb and Cd to the surface coatings mentioned above varied widely. There was a systemic increase in the maximum adsorption of Pb and Cd to the surface coatings with increasing the contents of Mn and Fe oxides in the surface coatings in significant correlation, respectively, not only highlighting the relative importance of the metal oxide fraction for Pb and Cd adsorption to the surface coatings developed in natural and technical water samples, but also implying the same adsorption mechanisms of Pb and Cd to the surface coatings developed both in natural and technical water samples.

INDIRECT VOLTAMMETRIC DETERMINATION OF TRACE SULFATE IN NATURAL WATERS WITH THE ADSORPTIVE COMPLEX WAVE OF LEAD(Ⅱ)-TETRAKIS (4-TRIMETHYLAMMONIUM PHENYL) PORPHYRIN

The indirect voltammetric determination of trace sulfate (2.0×10^(-6)～4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.This method has been used for the analysis of natural waters with satisfactory results.

Rice cultivation on floating-beds in different natural waters

Following the success in rice cultivation onfloating-beds in natural water in 1990,the eco-logical adaptability of growing rice on floating-beds was studied during the period of 1991-1993.Experiments were conducted in five dif-ferent types of natural waters in ZhejiangProvince from 28°35′ to 30°58′N and from 119°05′ to 121°11′E.The results indicated that:1)Yield of double-cropping early ricegrowing on floating-beds was lower than one

Suspended particulate and colloidal matter in natural waters

The association of pollutants (nutrients, heavy metals and organic compounds) with colloidal and suspended particle matter(SPM) plays a dominant role in determining their transport, fate, biogeochemistry, bioavailability and toxicity in natural waters. A scheme for the fractionation and composition of colloidal and suspended particulate matter from river waters has been tested. Sieving, continuous flow centrifugation and tangential flow filtration were used to collect gram amounts of colloidal and particulate matters. The separation scheme was able to process large samples(100L), within reasonable times(1 day) and the apparatus was portable. The aquatic colloid was also separated with high resolution, and sized using sedimentation field\|flow fractionation technique. The mass\|based particle size distribution for the river water sample showed a broad size distribution between 0\^05 and 0\^4 μm with the maximum around 0\^14 μm. There was a systematic increase in the content of organic carbon, Mg, Ca, Na, Cu and Zn with decreasing particle size, highlighting the importance of the colloidal(<1 μm) fraction.

Comment： Closing phosphorus cycle from natural waters： re-capturing phosphorus through an integrated water-energy-food strategy

Phosphorus （P） reserve, largely derived from phosphate rock, is essential for crop growth to support the growing world population. However, a significant proportion of phosphorus used as a fertilizer runs into natural waters, causing eutro- phication and ecological damage. Moreover, most P in the food is eventually discharged as waste after being digested by human and animals. Thus, industrial activities have created a one-way flow of non-renewable P from rocks to farms to lakes, rivers and oceans.

A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples

A novel catalytic kinetic method is proposed for the determination of Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in water based on the catalytic effect of Se（Ⅳ） on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se（Ⅳ） for the fixed-time method at 30℃. The experimental and theo- retical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L-1 for the fixed-time method （3 min）. All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se（Ⅳ） determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations （RSDs） for ten replicate measurements of 2, 10, and 20 μg·L-1 of Se（Ⅳ） change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L-1 of Se（Ⅵ） change between 0.49% and 1.61%. Analyses of a certified standard reference material （NIST SRM 1643e） for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se（Ⅵ） to Se（Ⅳ）.

Effect of Sample Disturbance on Unconfined Compression Strength of Natural Marine Clays

Quantitatively correcting the unconfined compressive strength for sample disturbance is an important research project in the practice of ocean engineering and geotechnical engineering. In this study, the specimens of undisturbed natural marine clay obtained from the same depth at the same site were deliberately disturbed to different levels. Then, the specimens with different extents of sample disturbance were trimmed for both oedometer tests and unconfined compression tests. The degree of sample disturbance SD is obtained from the oedometer test data. The relationship between the unconfined compressive strength q u and SD is studied for investigating the effect of sample disturbance on q u. It is found that the value of q u decreases linearly with the increase in SD. Then, a simple method of correcting q u for sample disturbance is proposed. Its validity is also verified through analysis of the existing published data.

Adsorption of Pb, Cd to Fe, Mn oxides in natural freshwater surface coatings developed in different seasons

Metal oxides(Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role in the fate and transport of trace metal in aquatic environments. Seasonal variation of Fe, Mn oxides and organic materials in surface coatings, which were developed periodically on glass slides in Nanhu Lake, Jilin Province, China over the time frame of three seasons, was investigated in order to understand the influence of metal oxides on Pb and Cd adsorption to heterogeneous surface coating materials(biofilm). Pb and Cd adsorption was measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0). The classical Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings. In general, components in the surface coatings varied greatly with seasons altering and obtained higher concentrations in summer while the content of iron oxides always exceeded that of manganese oxides. Correlation analyses between the maximum adsorption of Pb and Cd and components in the surface coatings developed periodically indicated that Pb phase association with Mn oxides and Cd phase association with Fe oxides as well as Mn oxides were statistically significant. Effect of Mn oxides on Cd adsorption was confirmed in view of its higher content in the surface coatings. The importance of ferromanganese oxides for Pb and Cd adsorption to the natural surface coatings developed in different seasons was evidenced.

On Physical and Mechanical Behavior of Natural Marine Intermediate Deposits

Coastal structures may be built on natural sedimentary intermediate grounds, which mainly consist of silty soils and fine sandy soils. In this study, extensive field and laboratory tests were performed on the natural marine intermediate deposits to demonstrate the difference in behavior between natural marine clayey soils and natural marine intermediate deposits. The natural intermediate deposits have almost the same ratios of natural water content to liquid limit as those of the soft natural marine clays, but the former have much higher in-situ strength and sensitivity than the latter. The research results indicate that grain size distributions of soils affect significantly tip resistance obtained in field cone penetration tests. The mechanical parameters of natural marine intermediate deposits are also significantly affected by sample disturbance due to their high sensitivity and relatively large permeability. Unconfined compression shear tests largely underestimate the strength of natural marine intermediate soils. The triaxial consolidated compression shear tests with simulated in-situ confined pressure give results much better than those of uncomfined compression shear tests.

Effects of natural mineral-rich water consumption on the expression of sirtuin 1 and angiogenic factors in the erectile tissue of rats with fructose-induced metabolic syndrome

Consuming a high-fructose diet induces metabolic syndrome （MS）-Iike features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular disease. Because mineral deficiency intensifies the deleterious effects of fructose consumption and mineral ingestion is protective against MS, we aimed to characterize the effects of 8weeks of natural mineral-rich water consumption on the structural organization and expression of vascular growth factors and receptors on the corpus cavernosum （CC） in 10% fructose-fed Sprague-Dawley rats （FRUCT）. Differences were not observed in the organization of the CC either on the expression of vascular endothelial growth factor （VEGF） or the components of the angiopoietins/Tie2 system. However, opposing expression patterns were observed for VEGF receptors （an increase and a decrease for VEGFR1 and VEGFR2, respectively） in FRUCT animals, with these patterns being strengthened by mineral-rich water ingestion. Mineral-rich water ingestion （FRUCTMIN） increased the proportion of smooth muscle cells compared with FRUCT rats and induced an upregulatory tendency of sirtuin I expression compared with the control and FRUCT groups. Western blot results were consistent with the dual immunofluorescence evaluation. Plasma oxidized low-density lipoprotein and plasma testosterone levels were similar among the experimental groups, although a tendency for an increase in the former was observed in the FRUCTMIN group. The mineral-rich water-treated rats presented changes similar to those observed in rats treated with MS-protective polyphenol-rich beverages or subjected to energy restriction, which led us to hypothesize that the effects of mineral-rich water consumption may be more vast than those directly observed in this study.

Experimental research on hydrophilic characteristics of natural soft rock at high stress state

In order to study features of rock–water interaction, a self-developed experimental system called Intelligent Testing System for Water Absorption in Deep Soft Rocks(ITSWADSR) was utilized to analyze the hydrophilic behaviors of natural soft rock at high stress state. Combining X-ray diffraction and mercury injection test, main influencing factors on hydrophilic characteristics were studied. According to the results, it could be concluded as the following:(1) the effective porosity, and the content of illite, illite/smectite formation(S = 5%) and kaolinite have positive correlation with the water absorption capacity of rock; meanwhile, the initial moisture content, fractal dimension of effective pores, illite/smectite formation(S = 30%) and chlorite present negative correlation;(2) among the positive factors, the ascending order is kaolinite, illite/smectite formation(S = 5%) and illite;(3) the descending order among the negative factors are chlorite, illite/smectite formation(S = 30%) and fractal dimension of the effective pores;(4) influence of effective porosity on the pressurized water absorbing capacity of rock is minimal, while it is maximal in the process of no pressurized water absorption.

Determination of complexation capacity of trace metal-organic in natural water

The complexation capacity for heavy metals (Cu, Cd, Pb) were determined by anodic stripping voltammetry in South China Sea, Hulun Lake and Wuliang Suhai. The conditional stability constants and complexation capacity index were calculated. The data showed that the complexation capacity of the Hulun Lake was greater than that of seawater and Wuliang Suhai. The sequence of complexation capacity is C (CuL)> C (CdL)> C (PbL), the values are in concord with results of analysis on dissolved organic carbon. The conditional stability constants were in an opposite sequence: K (CuL)< K (CdL)< K (PbL). When log K are similar, the greater the complexation capacity, the greater the complexation capacity index.

Electrokinetic chemical characteristics of humic and dannic acids effecting on the natural water and its coagulation

Taking streaming current(SC)as the electrokinetic parameter,this paper demon- strated the electrokinetic chemical characteristics of humic and dannic acids(HA and DA)in sus- pensions including turbid water,coagulated water and HA or DA contained water.Accordingly, the studies were carried out for determining the relationship between streaming current and zeta po- tential ζ(expressed by eleetrophoretie mobility EM)in above water conditions.In addition,the mechanisms of HA effecting on streaming current within or after coagulant addition and the elec- trokinetic detection principles for HA or DA were also investigated on experiments and theoretical analysis.The results indicated that the change of SC like ζ presented meaningful information con- cerning the degree for destabilization of a particulate suspension,and HA or DA in water could re- markably decrease the effect of inorganic coagulant upon streaming current,which is in accordance with their influence on coagulation.

High-Precision Direct Determination of the ^(87)Sr/^(86)Sr Isotope Ratio of Bottled Sr-Rich Natural Mineral Drinking Water Using MC-ICP-MS

Strontium has four naturally occurring stable isotopes,84Sr,86Sr,87Sr,and 88Sr,with abundances of 0.56,9.87,approximately 7.04,and 82.53 atomic %,respectively.The 87Sr/86Sr isotope ratio is variable due to the addition of radiogenic 87Sr produced by the beta decay of 87Rb with a half-life of 4.88 ± 0.05 Ga.Thus,

Pilot Trial on the Efficacy and Safety of a Natural Mineral Water Rich in Hydrogen Carbonate on Functional Dyspepsia and Heartburn

Background: Dyspepsia and heartburn are among the most frequent complaints of the upper gastrointestinal tract impacting quality of life. The present study aimed to investigate the impact of drinking a natural mineral water (medicinal product category “Heilwasser” in Germany) high in hydrogen carbonate (Staatl. Fachingen STILL) on functional dyspeptic complaints and heartburn. Methods: 56 men and women with self-reported heartburn were enrolled to this one-arm pilot study. They had to drink 1.5 L of a hydrogen carbonate rich mineral water each day over a course of six weeks. Participants reported the number and duration of heartburn episodes in a daily dairy. The Reflux Disease Questionnaire (RDQ), Quality of Life in Reflux and Dyspepsia questionnaire (QOLRAD) and the Gastrointestinal Quality of Life Index (GILQI) were used to assess the therapeutic course of the treatment and the Short Form Health Survey (SF-12) to assess general quality of life. Mean ± standard deviation were calculated and pre- and post-treatment changes were compared using the Wilcoxon test. Results: The consumption of a hydrogen carbonate rich mineral water decreased the number of heartburn episodes per week significantly by 4.8 ± 8.2 at the end of the study (p < 0.001). The duration of episodes was also significantly reduced by 25.7 minutes after six weeks of intervention (p < 0.001). Accordingly, the subjectively perceived severity of heartburn, regurgitation and dyspeptic complaints as well as the GERD dimension as assessed by Reflux Disease Questionnaire improved significantly. There was a significant improvement in the disease-specific quality of life as measured by the Gastrointestinal Quality of Life Index (p < 0.001) and by the Quality Of Life in Reflux and Dyspepsia (p < 0.001) questionnaires and the general health-related quality of life as assessed by SF-12 (p < 0.007). Conclusions: The present pilot study provides evidence that supplementation with natural mineral water rich in hydrogen carbonate may improve heartburn and dyspeptic symptoms, which finally resulted in an improvement of the subjectively perceived quality of life. Drinking mineral water rich in hydrogen carbonate may be an alternative remedy for the treatment of dyspeptic symptoms and heartburn. Trial Registration: Eudra CT No 2013-001256-36.

Adsorption characteristics of copper in rivers contaminated by acid mine drainage from copper mine

In this paper, the partitioning of copper between surfacial sediments and overlaying water in Dawu-Le An River, which was contaminated by acid mine drainage resulted from mining activities,was studied by field investigation and acid dissolution experiment.Simulated adsorption experiments were carried out to study the adsorption of copper on amorphous iron oxyhydroxide and ore tailing particles.The results showed that it was the binding of copper onto the surface of amorphous Fe/Al oxyhydroxides and ore tailing particles that regulated the concentrations of dissolved Cu at downstream of Dawu River and its inlet into Le An River.A significant part of adsorbed copper was likely to be associated with amorphous Fe/Al oxyhydroxides coated on the surface of ore tailing particles. A simplified surface complexation model can be used to describe the adsorption behavior in the river.

Determination of gross α and β activities in Zouma River based on online HPGe gamma measurement system

This paper describes a low-cost and fast method to evaluate gross α and β^(-) radioactivities in natural water based on an online high-purity germanium detector gamma measurement system.The major gamma activities in natural water are provided by natural and artificial radionuclides such as ^(40) K,^(137)Cs,and radionuclides belonging to ^(238)U and ^(232)Th series.The main a emitters related to gamma emissions in natural water are ^(224)Ra(240.98 keV)and ^(226)Ra(186.21 keV),and the β^(-) emitters are ^(40) K(1460.85 keV),^(214)Bi(609.31 keV),^(208)Tl(583.19 keV),and ^(214)Pb(351.93 keV).The formula for gross α and β^(-) activity concentration is based on these radionuclides,and the short half-life decay products are considered in the calculation.The detection efficiency of the device across energy region(0–3 MeV)is obtained through Monte Carlo simulation,and a calibration experiment is conducted to verify the simulation results.Gamma radioactivity is measured continuously for 114 d in Pixian County and Dongfeng Canal located in the Zouma River,Chengdu,Sichuan Province,China.A comparison of the calculation results and monitoring data from the Sichuan Management and Monitoring Center Station of Radioactive Environment indicates that the percentage and absolute error of a activity concentration is lower than 53%and 0.02 Bq/L,respectively,and that of β-activity concentration is lower than 33.2%and 0.016 Bq/L,respectively.The method can rapidly determine gross α and β^(-) activity concentrations in natural water online.

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 kt 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 differ- ence 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 Ca^2＋ and Mg^2＋ in tap water and natural water.

Application of Golden Section Method to Channel Transect Design

During the desing of channel transect,the paper brings forward golden section method,which is 0.618 methods.In order to reduce the calculation volume of the natural depth of water h 0 and bottomˉwidth b which apply trial calculation method and graphic method,and improve the calculate precision,the mathematical model has been built up,the writer combines example to explain the train of thought,the result shows that the calculation precision is high,the correctness is tested and verified by the result which is calculated by hand.It can be referred to the hydroelectric works.