Water quality and growth of phytoplankton for the Yellow River estuary reservoirs—The nutrients release from reservoir sediments

Effects of nutrients released from sediments on eutrophication in lakes and reservoirs were not well known in China. In the test, the release conditions of nitrogen and phosphorus from the sediments were observed by batch experiment. The test results revealed that the content released is correlated to the initial content of organic matter in sediments. In the Gengjing area, when the water quality of waterway, grit chamber and reservoir were compared, the water quality of the waterway was the highest, and lowered in the order of the grit chamber and the reservoir. The grit chamber could get not only fine sand removal but also the organic substance, nitrogen, phosphorus and phytoplankton, therefore it is important to operate and maintain the grit chamber to preserve the water quality of the reservoir. Due to little organic substance in sediments, ammonium nitrogen and phosphorus weren’t released during the incubation. But from the absorptiometric turbidity unit (ATU) test results, although the release of ammonium concentration was very low, ammonium oxidizing and nitrite oxidizing bacteria existed in sediments.     

Water quality and growth of phytoplankton for the Yellow River estuary reservoirs—current status of water environment

In this paper,the characteristics of the water quality in Yellow River estuary reservoirs were surveyed and the progress of the eutrophication was investigated by observing the behavior of nitrogen and phosphorus.The results showed that the concentration of dissolved inorganic nitrogen and total nitrogen was very high in all the reservoirs,and the level of nitrogen was eutrophic state.According to Vollenweider’s type model for phosphorus load,the total phosphorus was close to permissible load in Guangnan and Xinan reservoirs.But sometimes,the total phosphorus exceeded an excessive load in Gengjing reservoir.In Yellow River estuary reservoirs,Cyanobacteria,and Diatom phytoplankton were observed mainly,and the cyanobacteria was a the dominant species in summer.     

Chromium leaching mechanism of coal mine water—a modeling study based on Xuzhou-Datun coal mine district

In order to investigate chromium contamination of coal mine water, to analyze chromium leaching mechanism and to evaluate environment pollution potential of coal mine water, we perform site investigations, physical and computer modeling in the Xuzhou-Datun coal mine district. The result of our test samples shows that chromium concentration was 9 μg/L in roof leachate and 3 μg/L in coal leachate. The host rock has a higher pollution potential than that of coal seams. Leaching experiments and XRD test results indicate that chromium is released from the process of transforming illite to kaolinite. The pH, pe and temperature of coal mine water affect the chromium leaching behavior. Modeling results suggest that the adsorption of adsorbents controls chromium concentration in coal mine water. The chromium adsorption ratio is quite low in both an acid and in an alkaline environment. Therefore, coal mine water has a high pollution potential. Under other conditions, chromium adsorption is stronger in a neutral water environment, so that chromium concentrations may be very low.     

Bio-decomposition of rock phosphate containing pyrites by Acidithiobacillus ferrooxidans

Leaching soluble phosphorus from rock phosphate containing pyrites by Acidithiobacillusferrooxidans （A. f.） is feasible, and the reaction mechanism is as follows. Pyrites are oxidized by A. f. to produce H2SO4 and FeSO4; the rock phosphate is decomposed by H2SO4, forming soluble phosphorus compounds; and Fe^2＋ from FeSO4 is oxidized to Fe%3＋, providing energy for the growth ofA. f.. In this process, as H2SO4 is produced in the reaction, an acidic condition in the culture medium is formed, which benefits the growth ofA. f. and aids both continuous oxidation of pyrites and leaching of soluble phosphorus from rock phosphate. The fraction of phosphorous leached can reach the largest in the presence of 1.0 g/L Fe^3＋, 200 mg/L Mg^2＋ and 400 mg/L NH^4＋. The optimal technological parameters on the fraction of phosphorous leached are as follows： the volume fraction of inocula ofA. f., the mass ratio of pyrites to rock phosphate and the pH value are in ranges of 5%-25%, 3：1- 5：1 and 1.8- 2.2, respectively.     

Synthesis of N, N-diethyl dodecyl amine and its flotation properties on bauxite

N, N-diethyl dodecyl amine（DEN12） was synthesized from dodecyl amine, formic acid and acetic aldehyde. The collecting property of DENI2 on diaspore, kaolinite and illite was investigated by flotation test and infrared spectrum. The results show that in the presence of 2.0× 10^-4 mol/L DEN12, the recoveries of kaolinite and illite are all higher than 78% and the recovery of diaspore is 50% in the pH range of 5.5-6.0. The mass ratio of A1203 to SiO2 in concentrate obtained from separation artificial mixture is higher than 10, suggesting that DEN12 can be used as a collector to separate the aluminosilicates from diaspore in bauxite ores at the pulp pH below 8. The measurements of the infrared spectrum approve that the action between aluminosilicates and tertiary amine collector is strong electrostatic adsorption and that of diaspore is weak electrostatic adsorption.     

Pilot scale treatment of low turbidity water using compound bioflocculant and polymerized aluminium ferrum chloride

To investigate the application of compound bioflocculant (CBF) in drinking water treatment at pilot plant,CBF and polymerized aluminium ferrum chloride (PAFC) coagulant were used to treat raw water taken from Longhupao Reservoir in Heilongjiang Province for the removal of turbidity,COD,UV254 and residual Al. Coagulation test shows that the coagulation enhanced by CBF and PAFC exhibits more effective performance than that enhanced by the individual of them,and the total combination dosage is lower than that of the individual. The residual Al from PAFC can be removed efficiently by CBF. The removal efficiency of turbidity reaches 76.6% by combining CBF of 2 mg/L and PAFC of 15 mg/L,COD is decreased from 3.80 mg/L to 1.62 mg/L,and the concentration of residual Al is only 0.033 mg/L in the product water. It can be speculated that adsorption-bridging and sweep-coagulation processes are predominant in the flocculation process by the combination of CBF and PAFC.     

Physical and Chemical Properties of Sediments in Huainan Segment of Huaihe River

The chemical and physical properties of nitrogen and phosphorus as well as their concentrations in the overlying water, pore-water and sediments in Huainan segment of the Huaihe river were analyzed. The chemical forms of phosphorus in sediments were differentiated by a sequential fraction method. The results revealed that the NH4^ -N content in pore-water of 6 surface sediments is obviously higher than that in overlying water, indicating that there is a dynamic tendency of releasing NH4^ -N from sediment into overlying water. Chemical compound of nitrogen differs among segments of the river, while phosphorus has no such difference. Calcium bound phosphate (Ca-P) and iron bound phosphate (Fe-P) accounts for 60 % of the total phosphorus, and occluded-P (O-P) accounts for less than 20 %. Our findings indicate that 1) industrial waste water and domestic sewage have contributed to the excessive nutrient salts in Huaihe river, 2) decreased water flow during low water periods, and the interaction between sediments and overlying water disturbed by transport ships accelerate nutrient salt releasing into overlying water, which results in eutrophication of the river.     

Hydrogeochemical Characteristics of Fluorine in Shallow Groundwater of Tongshan Area

Tongshan area, a part of the floodplain of the abandoned Huanghe River, is one of the popular endemic fluorosis areas in East China. One of the reasons is high concentration of fluorine in shallow groundwater. Test results of 36 groundwater samples show that fluorine concentration in shallow groundwater is 0.18-6.7mg/L and 50% of the samples exceed the Chinese drinking water quality standard. There exists a significant negative correlation in content between Ca^2 and F^-. The correlations between fluorine concentration and other cations (for example Na^ , K^ , Mg^2 ) are not significant. The content of dissolved fluorine from the flooding sediments of the Huanghe River that varying from 5.6mg/kg to 15.2mg/kg plays an important role in forming the high fluorine groundwater. Usually, the dissolved fluorine content in silt is much higher than that in silty clay and clay. According to the geological investigation fluorine content in deep groundwater (over 60m) is less than 1.0mg/L and suitable for drinking, so it is an effective measure to prevent endemic fluorosis by extracting deep groundwater in disease areas.     

Strontium hydrogeochemistry of thermal groundwaters from Baikal and Xinzhou

This paper reports our work on the strontium hydrogeochemistry of thermal groundwa-ters in the Baikal Rift System (BRS) in Russia and Mongolia and the Xinzhou basin of the Shanxi Rift System (SRS) in northern China. Though similar in geological background, groundwaters from the BRS and the Xinzhou basin have different strontium isotope compositions. Both the strontium contents and the 87Sr/86Sr ratios of thermal water samples from Xinzhou are higher than those of most samples from Baikal. The major reason is the difference in hostrock geochemistry. The hos-trocks of the Xinzhou waters are Archaean metamorphic rocks, while those of the Baikal waters except the Kejielikov spring are Proterozoic or younger rocks. In the study areas, cold groundwaters usually show lower 87Sr/86Sr ratio due to shorter water-rock interaction history and lower equilibration degree. Strontium hydrogeochemistry often provides important information about mixing processes. Ca/Sr ratio can be used as an important hydrogeochemical pa     

Oil production rate predictions for steam assisted gravity drainage based on high-pressure experiments

Dual-well steam assisted gravity drainage(SAGD) has significant potential for extra-heavy oil recovery.China is conducting two dual-well SAGD pilot projects in the Fengcheng extra-heavy oil reservoir.Quick,direct predictions of the oil production rate by algebraic models rather than complex numerical models are of great importance for designing and adjusting the SAGD operations.A low-pressure scaled physical simulation was previously used to develop two separate theoretical models corresponding to the two different growth stages observed in the SAGD steam chambers,which are the steam chamber rising stage and the steam chamber spreading stage.A high-pressure scaled model experiment is presented here for one dual-well SAGD pattern to further improve the prediction models to reasonably predict oil production rates for full production.Parameters that significantly affect the oil recovery during SAGD were scaled for the model size based on the reservoir characteristics of the Fengcheng reservoir in China.Experimental results show the relationship between the evolution of the steam chamber and the oil production rate during the entire production stage.High-pressure scaled model test was used to improve the gravity drainage models by modifying empirical factors for the rising model and the depletion model.A new division of the SAGD production regime was developed based on the relationship between the oil production rate and the evolution of steam chamber.A method was developed to couple the rising and depletion models to predict oil production rates during the SAGD production,especially during the transition period.The method was validated with experiment data and field data from the literature.The model was then used to predict the oil production rate in the Fengcheng reservoir in China and the Athabasca reservoir in Canada.     

Experimental Research on the Autogenous Shrinkage of MK High Performance Concrete

Calcine and mill kaolin were used under agreeable technological conditions to generate matakaolin （MK）. The autogenous shrinkage performance of high performance concrete added with MK was researched. It is shown that MK has an effective inhibitory action to early autogenous shrinkage of cement concrete, and the inhibitory action increases with the increase of MK. The autogenous shrinkage values from 24 hours after placement to 56 days are all higher than those of the contrasted concrete, among which, the value of the concrete with 5% MK is the highest. But the total shrinkage values in 56 days are all less than those of the contrasted test pieces. The total contraction after 24 h of placement decreases as the increase of MK, moreover, it is greatly less than that of the contrasted ones.     

Test of subcritical crack growth and fracture toughness under water-rock interaction in three types of rocks

The subcritical crack growth and fracture toughness in peridotite, lherzolite and amphibolite were investigated with double torsion test. The results show that water-rock interaction has a significant influence on subcritical crack growth. With water-rock interaction, the crack velocity increases, while the stress intensity factor declines, which illustrates that water-rock interaction can decrease the strength of rocks and accelerate the subcritical crack growth. Based on Charlse theory and Hilling & Charlse theory, the test data were analyzed by regression and the correlation coefficients were all higher than 0.7, which shows the correlation is significant. This illustrates that both theories can explain the results of tests very well. Therefore, it is believed that the subcritical crack growth attributes to the breaking of chemical bond, which is caused by the combined effect of the tensile stress and the chemical reaction between the material at crack tip and the corrosive agent. Meanwhile, water-rock interaction has a vital effect on fracture toughness. The fracture toughness of samples under atmospheric environment is higher than that of samples immersed in water. And water-rock interaction has larger influence on fracture toughness in amphibolite than that in peridotite and lherzolite.     

Influence of heavy metal stress on morphology and physiology of Penicillium chrysogenum during bioleaching process

In order to improve the efficiency of bioleaching heavy metal from the contaminated soil using Penicillium chrysogenum （P chrysogenum）, experiment was conducted to evaluate the influence of heavy metal stress on P. chrysogenum during bioleaching. The morphology and physiology of P chrysogenum were observed. Assuming that the heavy metals are all leached out from the experiment soil, heavy metals are added into the agar medium by simulating the heavy metal content in the soil. It is concluded that the survivable heavy metal contaminated soil mass range for P. chrysogenum is 2.5-5.0 g. As for biomass determination, the contaminated soil is added into the liquid medium directly. The soil mass that P.. chrysogenum can be survivable is in the range of 2.5-8.75 g. In this mass range, the biomass of P. chrysogenum is bigger than that of the control sample. 10 g soil mass is the threshold of the growth ofP chrysogenum. 102.2 mg/L gluconic acid, 156.4 mg/L oxalic acid, 191.6 mg/L pyruvic acid, 0.02 mg/L citric acid, 0.03 mg/L malic acid and 70.6 mg/L succinic acid are determined after 15 d bioleaching. The mycelium is broken into fragments, and heavy metals are adsorbed on the cell wall or transported into the cytoplasm during bioleaching. The GOD activity declines from 1.08 U/mL to 0.2 U/mL under 400 mg/L of multi-metal stress. The influence of Pb on GOD activity is bigger than that of Cr and Cd, and the GOD activity is not influenced apparently by Mn, Zn and Cu.     

Effects of oxygen potential and flux composition on dephosphorization and rephosphorization of molten steel

The dephosphorization experiments of low phosphorus containing steel by CaO-based and BaO-based fluxes were carried out. The effects of the oxygen potential in molten steel and the BaO content in the slag on dephosphorization and rephosphorization of molten steel were analyzed. The results showed that the dephosphorization ratio of more than 50% and the ultra-low phosphorus content of less than 0.005% in steel were obtained by the three kinds of dephosphorization fluxes as the oxygen potential of molten steel higher than 400×10-6. Rephosphorization of molten steel was serious as the oxygen content of molten steel lower than 10×10-6. BaO-based fluxes can improve the dephosphorization effect and reduce the phosphorus pick-up effectively under the condition of weak deoxidization of molten steel (the oxygen potential is about 100×10-6), but can not prevent rephosphorization under the condi- tion of deep deoxidization of molten steel (the oxygen potential less than 10×10-6).     

Isotopic compositions of strontium in river water of Guizhou karst areas, China

We have carried out a study on the variation of strontium isotope composition of river waters, Wujiang and Yuangjiang River, in karst areas of Guizhou Province, China. The results obtained permit us to characterize the geochemistry of the river draining karst terrain and obtain a better understanding of main controls of catchment geology, chemical weathering of different rocks, and evaluate impact of human activities on the environment. The isotopic ratios of dissolved Sr in all rivers are between 87Sr/86Sr =0.7077 and 0.7110, totally lower than the weighted average of 87Sr/86Sr =0.7119 for the world large rivers. The Wujiang River waters have Sr concentrations from 1.0 to 6.1 μmol/L, while the Yuanjiang River waters have much lower Sr concentrations ranging from 0.28 to 1.3 μmol/L. Most of the river waters from the Wujiang river are characterized by low Ca/Sr and Mg/Sr, and 87Sr/86Sr ratios, in which a majority of river waters are of 87Sr/86Sr ratios lower than the average Sr isotope ratio (87Sr/86Sr     

Electrochemical synthesis of polyaniline in reverse microemulsion

The electro-polymerization behavior of aniline in reverse（W/O） microemulsion was investigated. The experiment results show that the cyclic voltammetry polymerization behavior of aniline in W/O microemulsion is different from that in aqueous solution remarkably. With the increase of scan cycle, the oxidation potential shifts positively and the reduction potential shifts negatively, i.e., the redox potential difference increases. H＋ apparent concentration affects the aniline polymerization evidently. When H＋ concentration is lower than 0.08 mol/L, the electro-polymerization of aniline is difficult. With the increase of H＋ concentration, the polymerization current of aniline increases gradually. Only when H＋ concentration is high enough（0.5 mol/L）, aniline can be well electro-polymerized. Moreover, under the same condition, the aniline polymerization current in W/O microemulsion is higher than that in aqueous solution. The scanning electron microscopy image shows that the deposited polyaniline（PANI） has uniform fiber morphology with diameter of about 100 nm. Further study result suggests that the electrochemical activity of the PANI in HCl is similar to that of the PANI prepared in aqueous solution.     

Effects of silica fume and steel fiber on chloride ion penetration and corrosion behavior of cement-based composites

This project was aimed to evaluate the chloride permeability and corrosion behavior of cement-based composites which comprised fibers and silica fume in the mixes. Resistivity, polarization resistance, ponding and rapid chloride penetration results of specimens were obtained through tests. Test results indicate that resistivity, open circuit potentials and direct current polarization of specimens with w/b ratio of 0.35 are higher than those of specimens with w/b ratio of 0.55. For length-diameter ratio of 65, resistivity and direct current polarization of specimens with fiber length of 35 mm were similar to those of 60 mm. In addition, the open circuit potentials of specimens with fiber length of 60 mm were slightly higher that those of 35 mm. The resistivity decreased with increasing steel fiber content, and the open circuit potential and direct current polarization increased with increasing steel fiber content. The specimens containing silica fume were found to provide higher resistivity, open circuit potentials and direct current polarization than the control specimens. The incorporation of steel fiber and silica fume in composites achieved more significantly decreases in resistivity and increases in direct current polarization than steel fiber composites or silica fume composites. The penetration depth and six-hour total charge passed of specimens for w/b ratio of 0.35 were lower than those for w/b ratio of 0.55. For length-diameter ratio of 65, the penetration depth of specimens for fiber length of 35 mm was similar to that of 60 mm. The penetration depth decreased with increased steel fiber content in the composites. By regression analysis, a good correlation between open circuit potential and direct current polarization, and chloride penetration depth and direct current polarization.     

Influence of three remineralization materials on physicochemical structure of demineralized enamel

This study aimed to evaluate the effect of three inorganic materials：casein phosphopeptide- amorphous calcium phosphate （CPP-ACP）, calcium sodium phosphosilicate （CSP） and sodium fluoride （NaF） on their remineralization potential. CPP-ACP, CSP and NaF were applicated in demineralized enamel for 4 h and then all enamel samples were immersed in remineralization solution. After 10 days, all samples were prepared for microhardness test, scanning electron microscopy （SEM） observation and the elemental level （%） analysis by energy dispersive X-ray spectroscopy （EDX）. The surface microhardness （SMH） values of three experimental groups were significantly higher than that of control group （P〈0.05）. The SMH value of NaF group was significantly higher than other experimental groups （P〈0.05）. The SEM micrographs showed that three remineralization materials caused distinct morphological changes and remineralized deposits were different from each other. EDX elemental analysis showed that there were significant differences in the Ca （wt%） and Ca：P molar ratio of the enamel layer among control and experimental groups. The Ca （wt%） and Ca：P molar ratio in NaF group were significantly higher than those of other experimental groups. There were no significant differences in P （wt%） among control and experimental groups （P〈0.05）. Three remineralization materials used in our study had the potential of remineralizing the demineralized enamel. NaF is the best and most feasible choice to be used in remineralizing the demineralized enamel.     

Experimental Study on Common and Steel Fiber Reinforced Concrete Under Dynamic Tensile Stress

Split Hopkinson technique has been developed to test the strength of common concrete and steel fiber reinforced concrete under dynamic tensile stress. Two types of test methods are considered, the splitting tensile test and a modified spalling test in which a specimen is loaded under uniaxial stress. The result shows that the dynamic strength enhancement of concrete is remarkable by using the reinforcing fiber. But for the common concrete, the base of compressive strength seems to show little effect on the tensile strength under dynamic loading. The experimental results also show that the resistance to tensile fracture of the steel fiber reinforced concrete for C100-mix is higher than those of CAO-mix.     

Vanadium extraction and dephosphorization from V-bearing hot metal with fluxes containing CaO

Extracting vanadium and removing phosphorus simultaneously by adding CaO containing materials to V-bearing hot metal were investigated under the condition of simulating the process of vanadium extraction with insufficiently supplying oxygen in converter. Through preliminary experiments, 3 h and 1375 °C were chosen as the optimum holding time and reaction temperature for formal experiments, respectively. The results of the formal experiments suggest that making basic slag can extract vanadium and remove phosphorus simultaneously. The vanadium extraction rate(ηV) and phosphorus removal rate(ηP) both increase with an increase in the basicity of the original slag materials and the Fe2O3 contents. The vanadium distribution ratio)(V L′is about an order of magnitude greater than the phosphorus distribution ratio),(P L′but the latter is more sensitive to slag basicity than the former. The phosphorus distribution ratio is beyond 6 when the basicity of the original slag materials is beyond 1, which indicates a much better performance of phosphorus removal compared to the phosphorus removal in the current process. Therefore, it is very feasible to properly raise slag basicity to remove phosphorus with consideration of the grade of vanadium slag. The relations between ηV and ηP, and between L′V and L′P are linear under the experimental conditions.