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1.
Duetoregionalhydrogeologicandclimaticconditions,inthewesternSongnenPlain,themostdistinctcharacteristicofwaterenvironmentinlimnicwetlandsisthatmanywaterbodieshavehighsaltcontentsandpHvalues,andsomelimnicwetlandsbelongtosaltmarshes.Thelimnicwetlandsofthisregionarespecialnaturecomplex.Itisimportantfortheutilizationofwetlandresourcesandtheintegrateddevelopmentofsaline-alkalinesoiltostudychemicalcharacteristicsofwaterenvironmentinthisregion.1NATURALENVIRONMENTCHARACTERISTICSOFTHEWE…  相似文献   

2.
Spectrum analyses of water quality time series have been carried out for five hydrometric stations including Wuhan hydrometric station of the Changjiang(Yangtze) River, etc. The fluctuations of Ca2+, Mg2+ and HCO 3 concentrations in river water under different physical geography conditions have about two-year cycle which is corresponding to hydrometeorological quasi-biannual-oscillation (QBO). Na+, Cl SO 4 2− have about two-year cycle in the area lightly affected by human activities while two-year cycle doesn’t exist in the area heavily affected by human activities. All the fluctuations of major ions have about three-month cycle. The river diseharge fluctuation accounts for 43.9%, 45.1%, 54.3%, 33.9%, 30.3% and 42.7% of the variance of Ca2+, Mg2+, HCO 3 , Na+, Cl, SO 4 2− , respectively, at Wuhan from 1962 to 1985. According to the spectrum characteristic of major ions, the duration of the time series has to be at least 13 years for trend analysis of monthly water quality data. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 49671017). Biography: XIA Xing-hui(1971-), female, a native of Hunan Province, Ph. D. Her research interest includes environmental chemistry.  相似文献   

3.
The densities of 36 water samples from the Huanghe River estuary and Bohai Bay were determinedby a magnetic float densimcter under three temperatures from 15℃ to 25℃.All the measured densities ofsamples were greater than that of the values calculated from the International Equation of State of Seawater.The differences between the measured and calculated densities increased with the decrease of salinities.The dif-ferences appeared exponentially correlated with[Ca~(2+)]/s,[Mg~(2+)]/s and[SO_4~(2-)]/s,and had"s"type curverelationship with the alkalinity in all salinity range.But in the salinity ranging from 25.72 to 31.57,therelationships were all linear.The density difference can be estimated from the equation △ρ(10~3kg·m~(-3))=(-2.79+236.5([Ca~(2+)]/s)/(-9.7464×10~(-3)+[Ca~(2+)]/s).It was the high alkalinity and[Ca~(2+)]/s that resulted in the measured densi-ties of seawaters being higher than the calculated densities in the Huanghe estuary and Bohai Bay.  相似文献   

4.
DuringthethreeMt.QomolangmaExpeditionsof1959-1960,1966-1968and1975,ChinesescientistshadobtainedmanydataofglaciersinthedistrictofMt.Qomolangma(Wangetal.,1980;Xieetal.,1975;Zhangetal.,1975).InMay1997,Prof.QinDaheandProf.PaulA.Mayewskiorganizedanothe…  相似文献   

5.
The International Eq一lation of State of Seawater,1980 and the PraeticalSalinity Scale,1978 have been adoPted by theUNESCO江CES沼COR八APSOJoint Panel ono‘eanogral,hie Tables and Standards(JPOTS),and endorsed bythese organizati6ns(Miller‘〕and Poisson,1981;Uneseo,1981).Th已new equa-tion and the Praetieal Salinity Seale are to be used for all values Published fromJan .1,1982 .The new equation 15 aeeurate for use in all oeeanie surfaee waters,but eannot be aeeurately aPPlied to…  相似文献   

6.
This study on dynamic changes of culture color,astaxanthin and chlorophylls,inorganic N including N-NO3^-,N-NO2^- and N-NH4^ in batch culture of Haematococcus pluvialis exposed to different additive nitrate concentration showed(1)ast/chl ratio was over 0.8 for brown and red algae,but was usually less than 0.5 for green and yellow algae;(2)N-NO3^-,in general,was unstable and decreased,except for a small unexpected increase in nitrate enriched treatment groups;(3)measurable amounts of N-NO2^- and N-NH4^ were observed respectively with three change modes although no extemal nitrite and ammonia were added into the culture;(4)a non-linear correlation between ast/chl ratio(or color)changes and the levels of N-NO3^-,N-NO2^-,N-NH4^ in H.pluvialis culture;(5)up and down variation of the ast/chl ratio occurred simultaneously with a perceptible color change from yellow to brown(or red)when N-NO3^-,N-NO2^- and N-NH4^ fluctuated around 30,5,5μmol/L respectively;(6)existence of three dynamic modes of N-NO3^-,N-NO2^- and N-NH4^ changes,obviously associated with initial extemal nitrate;(7)the key level of total inorganic N concentration regulating the above physiological changes during indoor cultivation was about 50 μmol/L;and(8)0.5-10mmol/L of nitrate was theoretically conducive to cell growth in batch culture.  相似文献   

7.
Myosin subfragment-1 was prepared from the myofibrils of bighead carp (Aristichthys nobilis). The myosin subfrag- ment-1 was proved to have the activity of tripolyphosphatase (TPPase) responding to the hydrolysis of sodium tripolyphosphate (STPP). The optimum temperature and pH for the TPPase of myosin subfragment-1 were 30℃ and pH 5.0, and at pH 8.0 the TPPase also showed a high activity. Mg2 was necessary to TPPase. The TPPase activity of myosin subfragment-1 was activated by Mg2 under low concentrations, but was inhibited when the concentration was over 17 mmolL-1. The TPPase activity was also affected by KCl. The optimum concentration of KCl for TPPase was 0.3 molL-1 under the condition of 17 mmolL-1 Mg2 . The TPPase activity was significantly inhibited by EDTA-Na2. Reagents such as KBr, KI and KIO3 could inhibit the TPPase effectively. K2Cr2O7 as well as KMnO7 and KNO3 exhibited weak inhibiting effects. The TPPase converted STPP to pyrophosphate (PP) and orthophosphate (Pi) stoichiometrically with a KM of 3.2 mmolL-1.  相似文献   

8.
In glacierized catchments, glacier runoff typically shows a strong diurnal cycle in the ablation season (June-September). To elucidate the effect of these processes on the chemical weathering, fresh snowfall and water samples were collected and studied from the supraglacial river, proglacial river, and gauging site in Qiyi glacierized catchment Qilian Mountains, Northwestern China, in the summer of 2011. The pH and electronic conductivity (EC) were determined in the field, and the concentrations of major ions (Na+, K+, Mg2+, Ca2+, Cl-, SO42-, NO3-) were measured. The results indicated that EC linearly increased with increasing distance from the glacial snout, and the concentrations of major ions increased with increasing water-rock interaction time. Along the flow path of the glacier runoff, Na+ and Cl- are more concentrated than other ions in the supraglacial river while Mg2+ and SO42- are more concentrated than other ions at the gauging site. The discharge, pH, EC, and the concentrations of major ions exhibited significant diurnal variation along the flow path. On the other hand, the amplitude of variation diminished from upstream to downstream along the flow path. The chemical weathering rate (Na++K++Mg2++Ca2+) was determined to be 10.9 t/yr/km2. Moreover, further research indicated that the sampling method influenced the assessment of chemical weathering rates. When the sample was collected randomly in one diurnal cycle of hydrography, the estimated ionic flux could deviate -47%~73% based on estimated hourly data. In contrast, if three samples were collected at peak, base flow and the discharge decreasing rate starts to slow down in one diurnal cycle of hydrography, respectively, the deviation would be less than 15%. The smaller the diurnal variation of discharge, the smaller deviation calculated.  相似文献   

9.
Effects of salinity, pH, nitrogenous and phosphate nutrients on the growth rate of four species of benthic diatoms were studied by using the method of in situ optical density measurement. The optimal culture conditions for the four species of diatoms are as follows: forAmphora coffeaeformis, s 35; pH 8.5; NO3 −N 1.54, NH4 +−N, 7.0; CO (NH2)2−N, 2.5 (mg/L); PO4 3−−P 1.13 (mg/L); forCocconeis scutellum varparva, s 30; pH 8.5; NO 3 −N 3.08, NH 4 + −N 3.5, CO(NH2)2−N 5.0 (mg/L); pO 4 3− −P 0.283 (mg/L); forNavicula corymbosa s 25; pH 8.0; NO 3 −N 1.54, NH 4 + −N 3.5 CO(NH2)2−N 5.0 (mg/L); PO 4 3− −P 0.565 (mg/L); forNavicula mollis. s 25; pH 8.0; NO 3 −N 1.54, NH 4 + −N 1.75, CO(NH2)2−N 1.25 (mg/L); PO 4 3− −P 0.141 (mg/L). Part of the results of this paper were exchanged in the Fourth Asian Aquaculture Forum. Oct. 16–20. 1995. Beijing, P. R. China.  相似文献   

10.
This paper reports the approprite ranges of Mg^2 ,Ca^2 and their ratio Mg^2 /Ca^2 in mixed seawater for rearing of Penaeus japonicus larvae,The ranges for the above three indices are 1150-1450mg/L,360-440mg/L and 2.8-3.4,respectively,the proper salinity range of mixed seawater is 22.1-33.9 obtained by mixing estuarine water and concentrated seawater.  相似文献   

11.
An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m−2) peaked in July, biomass (1.930 g·m−2) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m−2; biomass: 1.019 g·m−2 in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m−2 a−1, a little more than that (2.675 g wet wt m−2 a−1) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.  相似文献   

12.
1 INTRODUCTIONItisveryimportanttorealizethedistributionsofpollutantsbeforethepollutioncanbecontrolledsuc cessfully .Owingtothelackofsystematicalobserva tionsinabroadarea ,numericalsimulationhasbe comeapowerfultooltounderstandthedistributionsofpollutantsa…  相似文献   

13.
岩溶地下水是泰安市城区重要供水水源,近年来随着气候环境变化和人为活动的影响,岩溶地下水水化学特征日趋复杂,但其水化学特征及成因尚不明晰。为识别研究区地下水水化学特征、成因机制,本文采用数理统计方法、离子比值、水化学图解等方法,研究了该区岩溶地下水的水文地球化学特征。结果表明:研究区内岩溶地下水水化学类型主要为HCO3Ca型、HCO3·SO4Ca 型、HCO3·SO4·ClCa型。地下水水化学成分主要受水岩相互作用控制,以溶滤作用为主,地下水中的Ca2+、Na+、HCO-3、SO2-4主要来源于方解石、白云石的碳酸盐岩及石膏、盐岩等蒸发岩的溶解,且存在逆向的阳离子交替吸附作用,导致Ca2+含量增加,Na+含量减少,人为活动影响导致地下水中Cl-、NO-3浓度增加。研究成果为研究区内岩溶地下水的合理开发与保护提供了依据。  相似文献   

14.
Ice and snow chemistry of alpine glaciers is crucial for the research of regional atmospheric environment change. Fresh snow samples were weekly collected from Urumqi Glacier No.1 in the Tianshan Mountains, Xin- jiang, China, and the chemical characteristics and seasonal variations of major ions, mineral dust, δ18O and trace metals were measured. Results show that the concentrations of major ions in the snow are Ca2+ SO42- NH4+ NO3- Cl- Na+ Mg2+ K+, in which Ca2+ is the dominant cation, and SO42-is the dominant anion. All major ions have close positive correlations with each other except NO3-. δ18O shows positive correlation with air temperature change during the study period. Mineral dust particle and major ionic concentrations in fresh snow have obvious seasonal change, with high concentration in spring but low concentration in summer and autumn, which indicates that the chemical mass input from Asian dust activity to snow is very significant. Temporal changes of trace metals in fresh snow, e.g., Cd, Pb, Zn, Al, Fe, have shown that human-induced pollution of central Asian region also has large contribution to the snow chemistry on alpine glaciers of the Tianshan Mountains.  相似文献   

15.
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.  相似文献   

16.
The process-oriented model Forest-DNDC describing biogeochemical cycling of C and N and GHGs (greenhouse gases) fluxes (CO2, NO and N2O) in forest ecosystems was applied to simulate carbon sequestration and GHGs emissions in Abies fabric forest of the Gongga Mountains at southeastern edge of the Tibetan Plateau. The results indicated that the simulated gross primary production (GPP) of Abies fabric forest was strongly affected by temperature. The annual total GPP was 24,245.3 kg C ha^-1 yr^-1 for 2005 and 26,318.8 kg C ha^-1 yr^-1 for 2006, respectively. The annual total net primary production (NPP) was 5,935.5 and 4,882.2 kg C ha^-1 yr^-1 for 2005 and 2006, and the annual total net ecosystem production (NEP) was 4,815.4 and 3,512.8 kg C ha^-1 yr^-1 for 2005 and 2006, respectively. The simulated seasonal variation in CO2 emissions generally followed the seasonal variations in temperature and precipitation. The annual total CO2 emissions were 3,109.0 and 4,821.0 kg C ha^-1 yr^-1 for 2005 and 2006, the simulated annual total N2O emissions from forest soil were 1.47 and 1.36 kg N ha^-1 yr^-1 for 2005 and 2006, and the annual total NO emissions were 0.09 and o.12 kg N ha^-1 yr^-1 for 2005 and 2006, respectively.  相似文献   

17.
1 INTRODUCTION Chironomid larvae are main groups in most aquatic ecosystems, playing a crucial ecological role in decomposition of detritus and material ex- changes between water column and the sediment (Liang et al., 1995a, b; Chen, et al., 1982). They a…  相似文献   

18.
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.  相似文献   

19.
Sperm of sea cucumber Apostichopus japonicus (Selenka) were quiescent in electrolyte NaCl solution and artificial seawater (ASW) and nonelectrolyte glucose and mannitol solutions when the osmolality was less than 200 mOsm kg-1. The sperm started to be motile as a result of increased osmolality, indicating an osmolality-dependent initiation of sperm motility in sea cucumber. After a brief incubation in hypotonic NaCl and glucose solutions with osmolalities of 200 and 400 mOsm kg-1, sperm lost partial motile ability. Sperm became immobilized when pH was 6.0 in NaCl, glucose and mannitol solutions, suggesting that an H+ release is involved in sperm activation. The decreased pH had no effect on the percentage of motile sperm in ASW, whereas it delayed the time period to reach the maximum motility (motilitymax). Extracellular Ca2+ in electrolyte solutions was not essential for motility stimulation but shortened the time of reaching motilitymax. When Ca2+ was mixed in nonelectrolyte solutions the sperm motility was completely suppressed. The K+ channel blocker, quinine, suppressed the sperm motility in electrolyte solution, showing a possible involvement of K+ transport in the process. High K+ concentration did not affect the sperm motility in NaCl solution, but decreased it in ASW and almost entirely suppressed it in nonelectrolyte solutions. The different effects of pH and K+ in ASW and NaCl solution indicate that external ions may also regulate sperm motility.  相似文献   

20.
Free radical scavenging abilities of polypeptide from Chlamys farreri   总被引:1,自引:0,他引:1  
1 INTRODUCTION Active oxygen free radicals can damage cell structure, even kill the cells, causing aging and cer- tain serious diseases (Bors et al., 1989). Usually, the production and scavenging of active oxygen free radicals are in balance in healthy hu…  相似文献   

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