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1.
To ascertain the influence of hydrological boundary conditions on acidity fluxes in lakes influenced by acid mine drainage, acidity budgets were developed for two sediments in areas of differential groundwater inflow (approx. 1 L m?2 d?1 and 10 L m?2 d?1). In both sediments iron was deposited as schwertmannite leading to iron(III) enriched sediments (3.9…6.2 mmol g?1, referred to dry weight). Compared to the surface water, the inflowing groundwater had higher pH (4.5 vs. 3), ferrous iron (6…20 mmol L?1 vs. 0.8…2.0 mmol L?1), and sulfate (5…60 mmol L?1 vs. 8…13 mmol L?1) concentrations. The inflow changed the sediment pore water chemistry and triggered a further increase in pH to above 5.5. In both sediments acidity generation in the surface water (10…30 mol m?2 a?1) strongly prevailed over acidity consumption in the sediments (> ?0.6 mol m?2 a?1). With advective groundwater inflow, however, more acidity was consumed due to TRIS formation (?0.12 mol m?2 a?1 vs. ?0.017 mol m?2 a?1), iron carbonate burial (upper estimate: ?0.14 mol m?2 a?1 vs. ?0.022 mol m?2 a?1), and unspecific ferrous iron retention (?0.39 mol m?2 a?1 vs. ?0.08 mol m?2 a?1). Also, less acidity was generated due to schwertmannite transformation (?2.4 mol m?2 a?1 vs. ?0.11 mol m?2 a?1). The acidity balance of internal processes in the sediment with groundwater inflow was negative, whereas it was positive in the other sediment. The study demonstrates that in acidic and iron rich lakes the hydrological boundary conditions strongly affect geochemical processes as subsumed in acidity fluxes.  相似文献   

2.
In two test series, for which 10 and 2 … 4 g/1 wet matter of higher and lower aquatic plants from the lake Baikal and from the waters in the surroundings of Irkutsk were used, phenol solutions having concentrations of 10?3 … 10?5 M (1 … 5 mg/1) were applied. During the investigations the possible error clue to the presence of microorganisms was eliminated. The phenol decomposition by aquatic plants proceeds as a first-order reaction. The results of analyses are summarized in several tables and graphical representations.  相似文献   

3.
Solid‐contacted Potentiometric Electrodes for Measurements of Sulfate Ions in Aqueous Solutions A solid‐contact electrode for potentiometric measurement of sulfate ions in aqueous solutions was developed and examined. The electrode is based on a PVC membrane which contains the ionophore 3‐decyl‐1,5,8‐triazacyclodecan‐2,4‐dione (DTADD). Instead of the usual inner fluid junction, a polypyrrole layer applied on the inner side of the PVC membrane was employed as inner solid contact. The performance of this electrode was compared to solid‐state sulfate‐selective electrodes with the ionophore α,α′‐bis(N′‐phenylthioureylene)‐m‐xylene (BTH) and to electrodes in the coated‐wire configuration. For the parameters sensitivity, selectivity, and long‐term stability, electrodes with the DTADD ionophore show improved properties. In the sulfate concentration range of 5·10–5...10–2 mol L–1 the slope of the response is –(26.8 ± 0.5) mV/decade. The new solid contact sulfate electrodes showed a very low drift of the electrode potential within a period of 150 days when the electrode was stored in 10–2 M Na2SO4. In Na2SO4 solutions of the pH range of 4...9 the electrode potentials were constant. The 95% response time was about 10 s when the sulfate concentration was changed from 10–4 mol L–1 to 10–3 mol L–1. The selectivity with DTADD ionophore relating to the nitrate ions is higher than the selectivity with BTH. Improvements are also made in comparison with sulfate‐selective electrodes described in the literature which contain other ionophores with fluid inner reference electrolytes.  相似文献   

4.
In twelve flowing water (Q 1.04… 30.4 m3/s, 0.5… 1.2 m/s) the self-purification efficiency in 110 river sections (L 1.3… 26.4 km) is determined as the load difference in kg · d?1 COD-Mn as well as in g · m?3 referred to the daily passage. In the economical comparison, the self-purification efficiency is valued as substitution for wastewater treatment plants of the same capacity. At a mean specific capacity of 8.6 g · m?3, the self-purification efficiency of the investigated waters is equivalent to economical values of 124 · 103… 534 · 103 M km?1 investment costs, 11 · 103… 80 · 103 M · a?1km?1 operating costs and 5… 81 MWh · a?1 km?1 expenditure of energy. The specific capacity in g · m?3 COD-Mn shows an exponential regression to the degree of saprobity (L = 0.015 · exp (1.7358 · S)). From this empirical model the limits of the self-purification capacity of aerobic waters by oxygen input can be detected: in respective examples more than 50% of the required oxygen input are due to weirs.  相似文献   

5.
The sorption of Co(II) from aqueous solutions on granulated titanium dioxide was investigated in dependence on pH-value (pH = 6 … 10) and solution concentration (cL = 10?7 … 10?2 mol/kg) at 83 °C. The precipitation in the solution occurred at high pH-values and solution concentrations was determined by control experiments without the adsorber. The adsorption isotherms are S-shaped. This can be interpreted as transition from chemisorption at the basic material to surface precipitation.  相似文献   

6.
Static bioassay acute toxicity tests of Zinc, Copper and Mercury were conducted to determine the median lethal concentrations (LC50s) of a freshwater teleost Channa marulius (HAM .) The 96 h LC50 and 95% confidence limits for Zn2+ were 25.61 (24.13 … 27.12) mg/l; 0.90 (0.80 … 1.038) mg/l; for Cu2+ and 0.314 (0.257 … 0.371) mg/l for Hg2+. However, these values decreased at 240 h of exposure and were: 21.09 (18.29 … 24.60) mg Zn2+/l; 0.66 (0.568 … 0.841) mg Cu2+/l; and 0.131 (0.103 … 0.158) mg Hg2+/l. The relative potency ratio of Zn/Hg, Zn/Cu and Cu/Hg suggests that fish were most sensitive to Hg, followed by Cu and Zn ions. The acute toxicities of mixtures of Zn2+?Cu2+; Zn2+?Hg2+, Cu2+?Hg2+ and Zn2+?Cu2+?Hg2+ up to 48 h of exposure were also investigated. The additive index and ranges for Zn2+?Cu2+ were ?0.241 (-0.577 … 0.054); 0.056 (-0.269 … 0.475) for Zn-Hg; 0.285 (-0.043 … 0.718) for Cu-Hg; and -0.542 (-1.215 … 0.005) for Zn-Cu-Hg. All the mixtures tested showed a greater than additive toxicity because index ranges overlapped zero.  相似文献   

7.
The lake without any outlet (11 ha, 55000 m3, zmax 2,25 m) has a weak thermal stratification with maximum surface temperatures of 32.5 °C. The annual variation of temperature and depth of visibility is unimodal, with the maxima or minima in August. Phytoplankton consists mainly of Cyanophyceae. The primary production determined by the light-dark bottle technique (oxygen method) varies in the annual variation between 0.3… 0.5 g m?2 d?1 C (winter) and 3.4… 4.6 g m?2 d?1 C (summer); as the annual means of 1975 and 1976 there were found 1.9 and 2.4 g m?2 d?1 C, resp., gross production at a utilization of 0.42… 2.85% of the radiation energy. The chemism is a well-buffered hydrogen-carbonate water (pH 8.1… 9.0) with 74… 90 mg/1 Na and 20.5… 31.5 mg/1 K and with a good nutrient supply (20… 40 μg/1 PO4—P and 100… 240 μg/1 NO3—N) at the same time.  相似文献   

8.
A gas-sensitive electrode for the determination of ammonia was tested on the basis of potentiometry by means of parts of measuring devices from the CMEA region. Samples of water, cattle slurry, pig slurry and silo seepage water in the range of concentrations of 10?5 … 10?1 mol/1 NH4-N can be measured. Before measurement the samples have to get pH 11 and have to be diluted, if necessary. A maximum period of time of about eight minutes is required for attaining the potential constancy. The relative standard deviation varies between 0.1 and 4.79%; the rate of retrieval was 99.1% on an average. The results of the potentiometric measurements were equivalent to those of the acidimetric measuring method. The practical advantages consist in a low expenditure of material, energy and time.  相似文献   

9.
The differential-pulse polarography (DPP) and the stripping voltametry (SV) are investigated in detail with respect to their suitability for the quantitative detection of individual traces of heavy metals in sewage sludge. The results are checked on the basis of AAS analyses and by the standard-addition method. From the hydrochloric-acid extracts of fused sludge samples down to 1 μg/l can be detected by the SV, whereas the DPP reaches a sensitivity of 100 μg/l. The following basic electrolytes are used: Zn: 2 … 3 mol/l H3PO4; Cu: 0.4 mol/l K2CO3, 0.2 mol/l Na-K-tartrate, 0.1 mol/l HCl; Ni: 1 mol/l NH4OH, 1 mol/l NH4Cl, 25 ml/l triethylamine; Pb and Cd: 0.1 … 0.2 mol/l HCl.  相似文献   

10.
It has been found that ammonium ions belong together with potassium and sodium ions to the main cationic species in algal cells. The intracellular concentration of ammonium ions, which changes from 4 to 160 μmol. g?1 wet weight, strongly influences the influx and reflux of different ions. Algal cells containing 4… 6 μmol of ammonium ions per gram cumulate ammonium ions in the light with a very high initial rate of 40… 80 pmol. cm?2. s?1, whereas the influx of nitrite or nitrate ions is slower by more than one order. Whereas ammonium ions simply displace potassium ions from the cell, the uptake of nitrite and nitrate ions is more complicated. These ions are rapidly reduced inside the cell into ammonium ions, which is connected with the reflux of potassium and hydroxyl ions. Ammonium ions formed take part in metabolic reactions releasing hydrogen ions.  相似文献   

11.
In batch experiments with the metals labelled with their radionuclides the cumulation of zinc, cadmium and mercury on Scenedesmus obliquus in dependence on the pH-value is measured, because the original pH-value of the solution is changed by the algae due to their absorption of hydrogen-ions. For the uptake of zinc and cadmium the logarithm of the cumulation factor in the range of 2 … 5 is a linear function of the pH-value in the range of 5 … 9, cumulation increasing with rising pH-value. In contrast, the mercury cumulation is pH-independent. If the changed pH-value is taken into account, the cumulation factors are independent of the metal concentration in the range = 10?4 mol/l. The degree of cumulation is not changed by the presence of other metals. The cumulation factor is reduced by substances forming negatively charged complexes with the metals.  相似文献   

12.
Modern digital conductivity meters are readily portable, robust, cheap, and give precisely reproducible values of specific electrical conductivity (SpC, in µS cm?1). Here we investigate the accuracy of their estimates of the amounts of gypsum dissolved in waters collected in gypsum karst terrains, expressed as total hardness (TH) in mg L?1 of CaSO4·2H2O (GYP). Total dissolved solid concentrations (TDS) are also considered. Curves obtained with the program PHREEQC, for the dissolution of pure gypsum in water at 25 C, are compared with 574 comprehensive water chemical analyses selected from gypsum karst studies in Europe and the Americas. Principal common and foreign ions encountered are the BNC group (bicarbonates, nitrates, chlorides). It is found that GYP = 1·12·SpC + 62 where BNC < 33% (Cl? < 5%), with one standard error <5% for waters with SpC > 2400 µS cm?1; GYP = 0·74·SpC + 777 where BNC < 33% (5% ≤ Cl? < 15%), with one standard error <10% for waters with SpC > 3100 µS cm?1; GYP = 0·97·SpC ? 209 where BNC < 33% and Cl? ≥ 15%, with one standard error <10% for samples with SpC > 4300 µS cm?1. There are similar results for the more complex waters found in gypsum karsts where much carbonate rock or salt is also present, to the limit of BNC < 50% for what may reasonably be defined as ‘gypsum waters’. Values of R2 for linear correlations of different subsets of the water samples range from 0·69 to 0·96, the majority being >0·8. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

13.
Malachite green (MG), a traditional agent used in aquaculture although is not approved; its low cost and high efficacy make illicit use likely. We developed a small‐scale, simple, and sensitive dispersive liquid–liquid microextraction procedure for the assay of trace amounts of MG in aquatic environment of Trout fish. Fiber optic‐linear array detection spectrophotometry with charge‐coupled device detector benefiting from a microcell was used for this purpose. The method is based on enhancement effect of an anionic surfactant on the extraction of MG in to very fine multidroplets of microextraction solvent which made assisted by disperser solvent. Under the optimum conditions, the enrichment factor 77.5 was obtained from a 5‐mL water sample. The calibration graph was linear up to 5 × 10?7 mol L?1 with detection limit of 1 × 10?8 mol L?1. The relative standard deviation for seven replicate measurements of 4 × 10?7 and 5 × 10?8 mol L?1 of MG were 3.3 and 4.5%, respectively.  相似文献   

14.
The Gru?a Reservoir (located at 238…269 m a. s. l., volume 64.6 · 106 m3, surface 934 ha, drainage area 318 km2, max. depth 31 m, mean theoretical retention time 22 months) was investigated during the years 1996 to 2001. The obtained values of trophic state parameters (9…200 μg L?1 total phosphorus, 3…99 μg L?1 chlorophyll‐a, and 0.5…2 m transparency) indicate that water of the Gru?a Reservoir is eutrophic according to three types of classification: Carlson, OECD, and Jones and Lee. It was noticed that values of average biomass abundance are large in the Gru?a Reservoir, and they could indicate a richer trophic state. When these indices are cited in connection with parameters of the trophic state, it is apparent that the Gru?a Reservoir can be classified as a eutrophic water on the basis of total phosphorus content of chlorophyll‐a and hypertrophic water with respect to transparency.  相似文献   

15.
In this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10?3 mol L?1, and phase B was methanol (5 × 10?3 mol L?1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L?1, the LQs, 8.3 and 0.05 µg L?1, and the linear range from 10 up to 2000 µg L?1 and 0.05 up to 10 µg L?1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.  相似文献   

16.
The electrical conductivity of Tibetan eclogite was investigated at pressures of 1.5–3.5 GPa and temperatures of 500–803 K using impedance spectroscopy within a frequency range of 10-1–106 Hz. The electrical conductivity of eclogite increases with increasing temperature(which can be approximated by the Arrhenius equation), and is weakly affected by pressure. At each tested pressure, the electrical conductivity is weakly temperature dependent below ~650 K and more strongly temperature dependent above ~650 K. The calculated activation energies and volumes are 44±1 kJ/mol and-0.6±0.1 cm3/mol for low temperatures and 97±3 kJ/mol and-1.2±0.2 cm3/mol for high temperatures, respectively. When applied to the depth range of 45–100 km in Tibet, the laboratory data give conductivities on the order of 10-1.5–10-4.5 S/m, within the range of geophysical conductivity profiles.  相似文献   

17.
The present paper proposes the application of multiwalled carbon nanotubes (MWCNTs) as a solid adsorbent for selective separation/preconcentration of silver(I) in water samples prior to flame atomic absorption spectrometry. The procedure is based on the solid phase extraction of Ag(I)–2‐mercaptobenzothiazole chelate on MWCNTs. The elution step is carried out with 5 mL of 2 mol L?1 HNO3 in acetone solution at a flow rate of 1.0 mL min?1. The influences of the various analytical parameters including pH of the solution, eluent type, sample volume, flow rates of eluent, matrix ions were investigated for optimization of the presented procedure. Tests of addition/recovery for analyte ion in real samples were performed with satisfactory results. Preconcentration factor and limit of detection for Ag(I) were 160 and 0.21 µg L?1, respectively. The synthesized MWCNT exhibited excellent stability in eluent solution and its adsorption capacity was 5.4 mg of silver per gram of sorbent. The proposed method was successfully applied to trace silver determination in a variety of environmental water samples.  相似文献   

18.
A first-order degassing model was applied to describe the evolution of helium content and isotope composition in the earth and in the atmosphere. The main events described by the model are: (1) the earth-trapped primordial rare gases at the moment of its accretion; (2) later, the solid earth lost primordial and radiogenic rare gases, and (3) they were accumulated in the atmosphere; (4) in addition,3He was formed in the atmosphere due to cosmic irradiation, accretion from solar wind, etc.; (5)3He and4He dissipated into space at different loss rates.Study of this model confirms the concept that some of primordial helium is retained in the interior of the earth; terrestrial helium (3He/4He～ 2 × 10?5) was most probably formed as a mixture of primordial (3He/4He= 3 × 10?4) and radiogenic (3He/4He～ 3 × 10?8) helium. For achondritic concentrations of heavy radioactive elements (U= 2.25 × 10?8g/g) the calculated4He flux from the earth is equal to 5.7 × 106 at cm?2 sec?1. The corresponding3He flux is about 114 at cm?2 sec?1. In discussing the aeronomic problem of helium it is necessary to take into account that the earth is the main source of the light helium isotope.  相似文献   

19.
By the example of some phenols and qninones, in aqueous solutions possibilities for the quantitative determination are tested separately and in the mixture. Methods for thin-layer chromatography and spectrophotometry were developed. There can be chromatographically deteeted between 5 and 80 μg of substance. Phenol and quinone concentrations of 1.5 · 10?3 … 0.5 · 10?4 M were spectrophotometrically investigated.  相似文献   

20.
The device is used for the coulometric titration of chloride with electrolytically generated silver ions and biamperometric end-point indication via a second pair of silver electrodes. The device consists of the external measuring cell with the generator- and indicator-electrode systems and a magnetic stirrer as well as the titrator proper, which contains all electric and electronic components for the realization of the course of measurements up to the digital display of measured values. Four modes of operation can be chosen with the units mmol/1 Cl? or mg Cl? in 100 ml sample and sample volumes of 50 μ and 200 μl the compensation of systematic dosing errors or the taking into account of constant matrix effects being possible by means of a steplessly adjustable correction factor between 0.95 and 1.05. The measuring range is 25 … 2,000 mg/1 Cl? with variability coefficients between 0.3 and 3% if a microlitre pipette with a PE pipette tip is used. An even lower variability of the results can be expected from an improved sample dosing Disturbances caused by ions subject to electrolytic redox processes were detected (Fe, S2?, CrO42?).  相似文献   

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