Naphthalene Degradation Kinetics of Micrococcus sp., Isolated from Activated Sludge

Biodegradation of naphthalene by Micrococcus sp., isolated from the effluent of an activated sludge plant, was studied. The effects of pH (5–8), glucose concentration (100–1000 mg/L) and inoculum concentrations (1–5%) on the growth and naphthalene degradation potential of Micrococcus sp. were investigated. Maximum naphthalene degradation and subsequent high microbial growth were observed at optimum pH (pH 7), glucose concentration (500 mg/L) and inoculum concentration (3%). To investigate the maximum naphthalene tolerance potential of Micrococcus sp., very high concentrations of naphthalene (500–5000 mg/L) were used in the presence of non‐ionic surfactants. The examined surfactants (Triton X‐100 and Tween‐80) increased the bioavailability of naphthalene to the microbes and Complete naphthalene degradation by Micrococcus sp. was observed at an initial naphthalene concentration of 500 mg/L. However, the degradation potential decreases as the naphthalene concentration increases. Very high naphthalene concentrations also affected the growth of microbes and the corresponding substrate inhibition kinetics was described using four models (Haldane, Webb, Edward and Aiba). Based on correlation coefficient and percentage error values, all four substrate kinetic models were able to describe the dynamic behavior of naphthalene biodegradation by Micrococcus sp.     

IR-spektroskopische und weitere Untersuchungen an neuen Weichspüler-Wirkstoffen

IR Spectroscopy and Further Analyses of New Fabric Rinse Agents Distearyldimethylammoniumchloride (DSDMAC) that dominated the fabric softener market in Germany in the past is now substituted by three new types of ester-based agents, i.e. imidazoline ester, ester quats, and diester quats what poses new challenges to surface water analytics. The IR spectra and the chromatographic behaviour of these three agents are more or less similar to those of naturally occuring fatty esters. The paper reports about the use of IR spectroscopy, its benefit in the sense of fingerprinting principle, the identification of substances by functional groups, and the analytical tracing of transformation products. The latter relates to the formation of salts with anions that are easily detectable, the clean up, and the final spectroscopic determination. While in 1994 DSDMAC was still determinable in concentrations of 10…20 mg/kg in suspended solids from the Middle Rhine River, the concentration of the substitutes was below the detection limit of 2 mg/kg and 1…2 μg/L in 1995.     

Removal of Phosphate in Aqueous Solution by Permethylated Poly(ethyleneimine) Entfernung von Phosphat mit permethyliertem Poly(ethylenimin) in wäßriger Lösung

The use of cationic, water-soluble, permethylated poly(ethyleneimine) (PMP) for the removal of phosphate ions was investigated using the Liquid-phase Polymer-based Retention (LPR) technique. The results showed that the retention values were dependent on the filtration factor (Z) and pH. In the presence of 10 mg/L phosphate and 1% PMP, 52% of the phosphate was retained at pH = 1.0 and 93% at pH = 8.5 for Z = 2. However only 11% of phosphate was retained at pH = 1.0 and 80% at pH = 8.5 for Z = 5. The maximum binding capacity of phosphate by 1% of PMP was 22 mg phosphate per gram of PMP at pH = 1.0 and 185 mg phosphate per gram of PMP at pH = 7.0. The influence of nitrate, chloride, and sulfate ions on the interaction of phosphate ions with PMP was also investigated. It was found that the interaction is strongly influenced by sulfate ions. In addition, viscosimetric measurements were performed and discussed.     

Vergleichende Untersuchungen über das Phosphataufnahmevermögen ausgewählter Bakterienarten

The P-uptake by Acinetobacter calcoaceticus, Pseudomonas aeruginosa and Escherichia coli is determined in batch culture with peptone/glucose/sodium chloride or peptone/acetate/sodium chloride as substrate at 60 to 120 mg/1 orthophosphate for 20 h with cell densities of 2 · 10⁷/ml (Acinetobacter) or 1.2 · 10⁹. The measurements were carried out by means of an Na₂HPO₄ (³²P) addition of 95 to 420 kBq. During the stationary phase the bacteria achieved the following P-contents in the biomass in fg/g bacterium: Acinetobacter 6 to 13, Pseudomonas 0.2 to 0.6, Escherichia 0.04 to 0.09; during the phase of growth Acinetobacter achieved 40 to 100 fg/bacterium. Acetate as the substrate did not result in any increase of the P-uptake. The maximum accumulation with Acinetobacter was 13 % P in the dry substance.     

Bioremediation Management Reduces Mass Discharge at a Chlorinated DNAPL Site

Adaptive site management and aggressive bioremediation in the source zone of a complex chlorinated dense nonaqueous phase liquid (DNAPL) site reduced total chlorinated hydrocarbon mass discharge by nearly 80%. Successful anaerobic bioremediation of chlorinated hydrocarbons can be impaired by inadequate concentrations of electron donors, competing electron acceptors, specific inhibitors such as chloroform, and potentially by high contaminant concentrations associated with residual DNAPL. At the study site, the fractured bedrock aquifer was impacted by a mixture of chlorinated solvents and associated daughter products. Concentrations of 1,1,2,2‐tetrachloroethane (1,1,2,2‐TeCA), 1,1,2‐trichloroethane (1,1,2‐TCA), and 1,2‐dichloroethane (1,2‐DCA) were on the order of 100 to 1000 mg/L. Chloroform was present as a co‐contaminant and background sulfate concentrations were approximately 400 mg/L. Following propylene glycol injections, concentrations of organohalide‐respiring bacteria including Dehalococcoides and Dehalogenimonas spp. increased by two to three orders of magnitude across most of the source area. Statistical analysis indicated that reaching volatile fatty acid concentrations greater than 1000 mg/L and depleting sulfate to concentrations less than 50 mg/L were required to achieve a Dehalococcoides concentration greater than the 10⁴ cells/mL recommended for generally effective reductive dechlorination. In a limited area, chloroform concentrations greater than 5 mg/L inhibited growth of Dehalococcoides populations despite the availability of electron donor and otherwise appropriate geochemical conditions. After implementing a groundwater recirculation system targeting the inhibited area, chloroform concentrations decreased permitting significant increases in concentrations of Dehalococcoides and vinyl chloride reductase gene copies.     

Adsorption of BTEX on Surfactant Modified Granulated Natural Zeolite Nanoparticles: Parameters Optimizing by Applying Taguchi Experimental Design Method

In this paper, a novel adsorbent developed by means of granulating of natural zeolite nanoparticles (i.e., clinoptilolite) was evaluated for possible removal of the petroleum monoaromatics (i.e., benzene, toluene, ethylbenzene, and xylene, BTEX). To do this, the natural zeolite was ground to produce nanosized particulate, then modified by two cationic surfactants and granulated. The effect of various parameters including temperature, initial pH of the solution, total dissolved solids (TDS), and concentration of a competitive substance (i.e., methyl tert‐butyl ether, MTBE) were studied and optimized using a Taguchi statistical approach. The results ascertained that initial pH of the solution was the most effective parameter. However, the low pH (acidic) was favorable for BTEX adsorption onto the developed adsorbents. In this study, the experimental parameters were optimized and the best adsorption condition by determination of effective factors was chosen. Based on the S/N ratio, the optimized conditions for BTEX removal were temperature of 40°C, initial pH of 3, TDS of 0 mg/L, and MTBE concentration of 100 µg/L. At the optimized conditions, the uptake of each BTEX compounds reached to more than 1.5 mg/g of adsorbents.     

Pump‐and‐Treat Groundwater Remediation Using Chlorine/Ultraviolet Advanced Oxidation Processes

Comparative studies of the use of chlorine/ultraviolet (Cl₂/UV) and hydrogen peroxide/ultraviolet (H₂O₂/UV) Advanced oxidation processes (AOPs) to remove trichloroethylene (TCE) from groundwater in a pump‐and‐treat application were conducted for the first time at the full‐scale operational level at two water treatment facilities in Northern California. In these studies, aqueous chlorine replaced hydrogen peroxide in the AOP treatment step, where the oxidant is exposed to UV light to produce highly reactive radical species that degrade groundwater contaminants. TCE removal rates as a function of initial chlorine dose and pH were then determined. At the site where the natural pH of the water was 7.1, TCE was removed (to a concentration of less than 0.5 µg/L) for nearly every chlorine dose point tested, and pH adjustment slightly enhanced the treatment process at this facility. The second site had a high natural pH of 7.7, and here, TCE was not completely removed for any chlorine dose up to 5.7 mg/L, although TCE removal did increase when the chlorine dose increased between 0.9 and 3.6 mg/L. Residual TCE remaining in the water post‐Cl₂/UV was readily removed using active carbon filtration, which is part of the overall treatment train at this facility. These studies also verified that Cl₂/UV AOP did not interfere with the photolysis of N‐nitrosodimethylamine or result in an effluent acutely toxic toward Ceriodaphnia dubia. Comparative economic analysis revealed that the chemical costs associated with Cl₂/UV AOP were 25 to 50% of the costs associated with in place H₂O₂/UV AOP treatment.     

Sources of chloride in hydrothermal fluids from the Valles caldera, New Mexico: a Cl study

The Valles caldera in New Mexico hosts a high-temperature geothermal system, which is manifested in a number of hot springs discharging in and around the caldera. In order to determine the fluid pathways and the origin of chloride in this system, we measured ³⁶Cl/Cl ratios in waters from high-temperature drill holes and from surface springs in this region. The waters fall into two general categories: recent meteoric water samples with low Cl⁻ concentrations (< 10 mg/L) and relatively high ³⁶Cl/Cl ratios [(300–1000) × 10⁻¹⁵]; and geothermal brines with high Cl⁻ concentrations (800–9400 mg/L) but low ³⁶Cl/Cl ratios [(11–26) × 10⁻¹⁵]. The ³⁶Cl/Cl ratios for meteoric waters are slightly higher than expected for this region, suggesting a small addition of anthropogenic ³⁶Cl. Because of low ³⁶Cl/Cl ratios and high Cl⁻ concentrations in the brines, chloride in these waters must be derived from subsurface sources. A comparison between the observed ³⁶Cl/Cl ratios in the brines and those calculated for potential source formations in this region indicates that the present host formations, mainly volcanic tuffs, cannot be major sources of chloride, and that formations at greater depth, such as the Paleozoic and Precambrian formations are more likely to be sources of chloride in the brines. The results suggest that brines are meteoric waters which penetrated into the basement where they derive chloride from leaching of basement rocks and/or from saline pore fluids trapped there, along with likely addition of chloride from Paleozoic strata. Although these fluids have since come to reside in the intracaldera volcanic sequence after convective upwelling, they do not derive much Cl⁻ from the volcanic strata; and residence times of fluids in the volcanics are < 100,000 years.     

Bestimmung eines Gruppenparameters für organische Halogenverbindungen in Wasserproben mit hohen Salzgehalten unter Verwendung von XAD-4-Harz

Determination of a Group Parameter for Organic Halogen Compounds in High Salt-laden Water Samples Using XAD-4 Resin Concerning the often discussed ‘chloride error’ in AOX determination, a method is described with allows the determination of the group parameter organic halogen compounds (OX) for chloride concentrations more than 1 g/L. In opposite to the standard method DIN 38409 part 14, no chloride influence up to a concentration of 10 g/L in real water samples occurs. The basis of the method is the adsorption of the organic compounds from the water sample on XAD-4 resin, a nonpolar copolymer of styrene and divinylbenzene. The organic compounds are concentrated on the XAD-4 resin conditioned with methanol. After the enrichment step, the adsorption columns are treated with sodium nitrate solution. Model experiments with p-chlorophenol and chloride concentrations of 50 g/L showed the effectiveness of this method. The loaded and washed adsorption columns are first eluated with acetone and then with ethyl acetate. Quantification of the OX compounds in the eluates is carried out by microcoulometric detection after combustion in a furnace equipped with a special injector for eluates. For optimal work, the instrument was modified and improved. The presented method was developed on model samples and tested on different real samples.     

Microbial Mineralization of Dichloroethene and Vinyl Chloride under Hypoxic Conditions

Mineralization of ¹⁴C‐radiolabled vinyl chloride ([1,2‐¹⁴C] VC) and cis‐dichloroethene ([1,2‐¹⁴C] cis‐DCE) under hypoxic (initial dissolved oxygen (DO) concentrations about 0.1 mg/L) and nominally anoxic (DO minimum detection limit = 0.01 mg/L) was examined in chloroethene‐exposed sediments from two groundwater and two surface water sites. The results show significant VC and dichloroethene (DCE) mineralization under hypoxic conditions. All the sample treatments exhibited pseudo‐first‐order kinetics for DCE and VC mineralization over an extended range of substrate concentrations. First‐order rates for VC mineralization were approximately 1 to 2 orders of magnitude higher in hypoxic groundwater sediment treatments and at least three times higher in hypoxic surface water sediment treatments than in the respective anoxic treatments. For VC, oxygen‐linked processes accounted for 65 to 85% of mineralization at DO concentrations below 0.1 mg/L, and ¹⁴CO₂ was the only degradation product observed in VC treatments under hypoxic conditions. Because the lower detection limit for DO concentrations measured in the field is typically 0.1 to 0.5 mg/L, these results indicate that oxygen‐linked VC and DCE biodegradation can be significant under field conditions that appear anoxic. Furthermore, because rates of VC mineralization exceeded rates of DCE mineralization under hypoxic conditions, DCE accumulation without concomitant accumulation of VC may not be evidence of a DCE degradative “stall” in chloroethene plumes. Significantly, mineralization of VC above the level that could reasonably be attributed to residual DO contamination was also observed in several nominally anoxic (DO minimum detection limit = 0.01 mg/L) microcosm treatments.     

Chloride source delineation in an urban-agricultural watershed: Deicing agents versus agricultural contributions

Analyses (n = 525) of chloride (Cl⁻), bromide (Br⁻), nitrate as nitrogen (NO₃-N), sodium (Na⁺), calcium (Ca²⁺) and potassium (K⁺) in stream water, tile-drain water and groundwater were conducted in an urban-agricultural watershed (10% urban/impervious, 87% agriculture) to explore potential differences in the signature of Cl⁻ originating from an urban source as compared with an agricultural source. Only during winter recharge events did measured Cl⁻ concentrations exceed the 230 mg/L chronic threshold. At base flow, nearly all surface water and tile water samples had Cl⁻ concentrations above the calculated background threshold of 18 mg/L. Mann–Whitney U tests revealed ratios of Cl⁻ to Br⁻ (p = .045), to NO₃-N (p < .0001), to Ca²⁺ (p < .0001), and to Na⁺ (p < .0001) to be significantly different between urban and agricultural waters. While Cl⁻ ratios indicate that road salt was the dominant source of Cl⁻ in the watershed, potassium chloride fertilizer contributed as an important secondary source. Deicing in watersheds where urban land use is minimal had a profound impact on Cl⁻ dynamics; however, agricultural practices contributed Cl⁻ year-round, elevating stream base flow Cl⁻ concentrations above the background level.     

生物质炭对苦草(Vallisneria spiralis)种子萌发与生长的影响

为了探究生物质炭作为生长基质对水生植物种子萌发和生长的影响,选用典型沉水植物苦草(Vallisneria spiralis)作为受试植物,测定不同氮、磷营养盐浓度和不同粒径的生物质炭作用下对苦草种子萌发率、幼苗形态与生物量,同时分析水体中硝态氮、亚硝态氮、氨氮和正磷酸盐磷浓度变化过程.结果表明:生物质炭存在使水体中亚硝态氮浓度低于检测限,使水体正磷酸盐磷浓度上升至1.28~2.43 mg/L,为最高添加磷浓度的3.2~6.1倍,从而改变了苦草生长环境.小粒径生物质炭(0.25~0.5 mm)组中水体最终氨氮浓度(0.05 mg/L)远远低于大粒径生物质炭(1~2 mm)组中水体最终氨氮浓度(0.39~0.85 mg/L),即生物质炭粒径大小会影响水体最终营养盐浓度和氮素赋存形态.与大粒径生物质炭组和石英砂对照相比,小粒径组苦草种子萌发率明显升高,可达80%以上,并促进苦草幼苗生长.因此,小粒径生物质炭能提高苦草种子萌发和幼苗生长,在大型水生植物恢复工程中具有一定的应用前景.     

Bioremediation of Phenanthrene by Mycoplana sp. MVMB2 Isolated from Contaminated Soil

The effect of nutrient and surfactant addition on the biodegradation of phenanthrene was studied in a batch scale soil–slurry system using isolated Mycoplana sp. MVMB2strain. The study was conducted using an artificially phenanthrene spiked and as well as contaminated soil from petrochemical industrial site. Maximum phenanthrene degradation and subsequent high microbial growth were observed at optimum pH (pH 6) and C/N/P ratio (100:20:3). To investigate maximum substrate degradation potential of Mycoplana sp. MVMB2, very high concentrations of phenanthrene (50–200 mg/kg soil) were used. The organism was capable of degrading >60% for a concentration below 20 mg/kg soil and >40% for concentrations up to 200 mg/kg within 8 days. Further the influence of five different surfactants namely Span 80, Tween 20, Triton X‐100, cetyl trimethyl ammonium bromide, and sodium dodecyl sulfate were tested at their critical micelle concentration (CMC) levels for phenanthrene degradation in the soil. The addition of surfactant enhanced the biodegradation and a maximum of 84.49% was obtained for Triton X‐100. Complete phenanthrene degradation by Mycoplana sp. MVMB2 was observed at 3 CMC concentration of Triton X‐100. The optimized parameters obtained were used for the degradation of phenanthrene present in the contaminated soil and 98.6% biodegradation was obtained. Thus, the results obtained in the study suggested that biodegradation of phenanthrene by Mycoplana sp. MVMB2 appeared to be feasible to remediate phenanthrene rich contaminated sites.     

Permeable Asphalt: A New Tool to Reduce Road Salt Contamination of Groundwater in Urban Areas

Chloride contamination of groundwater in urban areas due to deicing is a well‐documented phenomenon in northern climates. The objective of this study was to evaluate the effects of permeable pavement on degraded urban groundwater. Although low impact development practices have been shown to improve stormwater quality, no infiltration practice has been found to prevent road salt chlorides from entering groundwater. The few studies that have investigated chlorides in permeable asphalt have involved sampling directly beneath the asphalt; no research has looked more broadly at surrounding groundwater conditions. Monitoring wells were installed upgradient and downgradient of an 860 m² permeable asphalt parking lot at the University of Connecticut (Storrs, Connecticut). Water level and specific conductance were measured continuously, and biweekly samples were analyzed for chloride. Samples were also analyzed for sodium (Na), calcium (Ca), and magnesium (Mg). Analysis of variance analysis indicated a significantly (p < 0.001) lower geometric mean Cl concentration downgradient (303.7 mg/L) as compared to upgradient (1280 mg/L). Concentrations of all alkali metals increased upgradient and downgradient during the winter months as compared to nonwinter months, indicating that cation exchange likely occurred. Despite the frequent high peaks of chloride in the winter months as well as the increases in alkali metals observed, monitoring revealed lower Cl concentrations downgradient than upgradient for the majority of the year. These results suggest that the use of permeable asphalt in impacted urban environments with high ambient chloride concentrations can be beneficial to shallow groundwater quality, although these results may not be generalizable to areas with low ambient chloride concentrations.     

Enhancement of Limestone Defluoridation of Water by Acetic and Citric Acids in Fixed Bed Reactor

Limestone defluoridation by fixed bed reactor has been studied with water pre‐acidified with edible organic acids, viz. acetic acid (AA) and citric acid (CA). The study has been carried out by varying acid concentration, contact time (t), number of repeated use of the same limestone bed (n), and chip size of the crushed limestone using fixed fluoride concentration of 10 mg/L in distilled water and groundwater amended to that concentration of fluoride. The presence of both the acids considerably improved the fluoride removal and the removal increased with increase in the acid concentration. Fluoride removal to less than 0.5 and 1.0 mg/L from initial 5 and 10 mg/L, respectively, have been achieved by the method on treatment with single reactor. The mechanism of fluoride removal in the process thought to be the increase in Ca²⁺ activity by dissolution of limestone, which precipitates as CaF₂. XPS analysis reveals that adsorption also contribute to the fluoride removal along with precipitation. The final pH of water remained within acceptable range for drinking water. Initial concentration of fluoride, effects the removal ability of the limestone particles only to some extent. The influence of other anions on fluoride removal process has a little influence which follows the order phosphate > sulfate > bromide > chloride > nitrate.     

Simultaneous and Sensitive HPLC Determination of Mono‐ and Disaccharides,Uronic Acids,and Amino Sugars after Derivatization by Reductive Amination

The reductive amination of low‐molecular‐weight saccharides, uronic acids, and amino sugars, followed by a separation of the derivates by means of ion‐pair chromatography or RP‐HPLC, offers an interesting alternative to HPAEC‐PAD for the environmental analysis of these compounds. Under this aspect various potential amination reagents, i.e., p‐amino‐benzoic acid (p‐AMBA), p‐AMBA propyl ester, 1‐aminopyrene, 2‐(2‐aminophenyl)indole, and 4‐aminoazobenzene, were tested with regard to the formation of derivates and to the chromatographic properties of the formed derivates. p‐AMBA, p‐AMBA propyl ester and 4‐aminoazobenzene proved to be especially suited, because they facilitate the amination of all carbohydrate reference components together with a complete separation and sensible detection (detection limits < 0.5 mg/L) of the derivates. Mainly the following elution sequence was ascertained: amino sugars (hexosamines) / disaccharide(s) / monosaccharides (hexoses) / hexuronic acid(s) / N‐acetyl‐D‐glucosamine. Detection limits down to 0.1 μmol/L were realized using p‐AMBA as reagent, facilitating the determination of the target compounds in landfill leachates and lysimeter percolates. Applying the p‐AMBA propyl ester for derivatization, chromatographic interferences with weakly retained derivates and the coelution of the reagent with its galactosamine derivate can be avoided, since the ester elutes after its derivates unlike p‐AMBA itself.     

Response Surface Approach for the Bisorption of Ag(I) by Macrofungus Pleurotus platypus

Response surface methodology (RSM) employing the three‐level Box–Behnken factorial design was used to optimize the biosorption of Ag(I) by the macrofungus Pleurotus platypus. The initial Ag(I) concentration (100–300 mg/L), pH (3.0–9.0), and biomass dosage (1.0–5.0 g/L) were chosen as the process variables for the optimization. A coefficient of determination (R²) value (0.99), model F value (234.18), and its low p‐value (F < 0.0001) along with the lower value of coefficient of variation (2.44%) indicated the fitness of response surface quadratic model during the present study. At the optimum pH (6.0), initial metal concentration (220 mg/L), and biomass dosage (3.0 g/L), the model predicted 46.7 mg/g Ag(I) uptake and an experimental 46.77 mg/g Ag(I) uptake by P. platypus was obtained. This is the first report on Ag(I) sorption by P. platypus using statistical experimental design employing RSM which may be helpful towards the treatment of industrial effluent containing silver.     

Start‐Up Study on Biohydrogen from Palm Oil Mill Effluent in a Pilot‐Scale Reactor

A start‐up study for biohydrogen production from palm oil mill effluent (POME) is carried out in a pilot‐scale up‐flow anaerobic sludge blanket fixed‐film reactor (UASFF). A substrate with a chemical oxygen demand (COD) of 30 g L^?1 is used, starting with molasses solution for 30 days and followed by a 10% v/v increment of POME/molasses ratio. At 100% POME, a hydrogen content of 80%, hydrogen production rate of 36 L H₂ per day, and maximum COD removal of 48.7% are achieved. Bio‐kinetic coefficients of Monod, first‐order, Grau second‐order, and Stover‐Kincannon kinetic models are calculated to describe the performance of the system. The steady‐state data with 100% POME shows that Monod and Stover‐Kincannon models with bio‐kinetic coefficients of half‐velocity constant (K_s) of 6000 mg COD L^?1, microbial decay rate (K_d) of 0.0015 per day, growth yield constant (Y) of 0.786 mg volatile suspended solids (VSS)/mg COD, specific biomass growth rate (μ_max) of 0.568 per day, and substrate consumption rate of (U_max) 3.98 g/L day could be considered as superior models with correlation coefficients (R²) of 0.918 and 0.989, respectively, compared to first‐order and Grau's second‐order models with coefficients of K₁ 1.08 per day, R² 0.739, and K_2s 1.69 per day, a = 7.0 per day, b = 0.847.     

淮南采煤塌陷湖泊浮游植物优势种的营养动力学

在淮南潘谢矿区选取3个营养盐结构差异较大的塌陷湖泊,于2014—2015年4个季度分别对浮游植物群落结构组成进行调查,选取3个湖泊中的优势种(属)具尾蓝隐藻(Chroomonas caudata)、链形小环藻(Cyclotella catenata)和伪鱼腥藻(Pseudanabaena sp.)作为研究对象,设置不同的氮(N)、磷(P)浓度梯度进行营养动力学培养实验,并结合Monod方程,获得3个藻种在不同营养盐限制下的营养动力学参数.N限制下具尾蓝隐藻、小环藻和伪鱼腥藻的最大生长速率(μmax)和半饱和常数(Ks)分别为:0.66 d~(-1)、1.66 mg/L;0.37 d~(-1)、1.06 mg/L;0.71 d~(-1)、2.26 mg/L;P限制下它们的μmax和Ks则分别为:0.51 d~(-1)、0.023 mg/L;0.31 d~(-1)、0.035 mg/L;0.90 d~(-1)、0.015 mg/L.综上所述,在N充足时,伪鱼腥藻能够在竞争中形成优势,同时在P限制情况下易成为优势种,从营养动力学的角度揭示了其在塌陷湖泊中占据优势的营养盐动力学机制.研究结果可以为沉陷区水域开发利用和营养盐管理提供科学依据.     

伊乐藻-草鱼圈养复合生态系统中水生生物的变化和影响

从细菌、浮游植物、浮游动物、底栖动物和有机碎屑等几个方面分析了养鱼对伊乐藻种植区(以下简称为有草区)和无草区水域环境的影响。结果表明:两个区域存在着显著的差异性。有草区由于生长着茂密的水生植被,对环境压迫的缓冲能力增强,水生生物的群落结构较为稳定,物种多样性指数高于无草区,有机物的沉降速率也大大低于无草区。与此相比,无草区对环境压迫的缓冲能力较差,水体浮游植物数量增加,富营养化加剧。通过本项实验可以看出,人工种植伊乐藻对养鱼区水质有着明显地控制作用,是发展生态渔业的一条有效途径。