THE EFFECT OF TENSION OF DISSOLVED OXYGEN ON THE TOXICITY OF UN-IONIZED AMMONIA TO SEVERAL SPECIES OF FISH

The resistance to rapidly lethal concentrations of un-ionized ammonia ranging from about 2.0 to 8.8 p. p. m. N was determined for rainbow trout ( Salmo gairdnerii Richardson), perch ( Perca fluviatilis L.), roach ( Rutilus rutilus (L.)), and gudgeon ( Gobio gobio (L.)) in tensions of dissolved oxygen 53.4 and 96.7% of air-saturation value at 15.2°C.
The relation between concentration of un-ionized ammonia and period of survival from a few hours to 13 days was investigated for rainbow trout in two tensions of dissolved oxygen, 45.7 and 100.3% of air-saturation value, at 20.1°C.
Period of survival of all the species tested decreased with rise in concentration of un-ionized ammonia.
Decrease in tension of dissolved oxygen increased the toxicity of un-ionized ammonia to all species except gudgeon, for which there was no significant difference in period of survival at the two levels of oxygen.
The effect of oxygen tension on period of survival was greatest in the lowest concentrations of un-ionized ammonia.
Resistance of perch and roach to lack of oxygen was not significantly affected, but that of rainbow trout was reduced significantly, by the presence of a small concentration of ammonia (not toxic to trout within at least 13 days).     

THE SURVIVAL OF RAINBOW TROUT (SALMO GAIRDNERII RICHARDSON) AND PERCH (PERCA FLUVIATILIS L.) AT VARIOUS CONCENTRATIONS OF DISSOLVED OXYGEN AND CARBON DIOXIDE

The relative importance of dissolved oxygen and dissolved carbon dioxide in determining the lethal effect of an environment for rainbow trout and perch has been investigated with an apparatus which controls the concentrations of these gases in a body of water. It is shown that concentrations of carbon dioxide which sometimes occur in polluted streams can more than double the minimum concentration of dissolved oxygen necessary for the survival of half a population of rainbow trout fingerlings for 24 hr. Increase in temperature between 12·5 and 19·5°C. shortens period of survival in solutions containing up to 67 p. p. m. CO₂. Within the range of dissolved oxygen concentration which is lethal in the presence of 59 p. p. m. CO₂ or more, perch are more resistant than rainbow trout in the lower, but less resistant in the higher, oxygen concentrations. The relation between carbon dioxide concentration and the oxygen tension at which rainbow trout blood is half saturated with oxygen is similar to the relation between carbon dioxide concentration and the oxygen tension at which the median period of survival of this species is I hr.     

Histology of cultured channel catfish, Ictalurus punctatus (Rafinesque)

Dissolved oxygen and un-ionized ammonia concentrations were monitored in 12 0.04 ha earthen ponds stocked with 10 000 channel catfish, Ictalurus punctatus ,/ha. Gill, liver and trunk kidney tissue samples were removed periodically for histological examination. Total ammonia and dissolved oxygen levels were in the ranges reported for catfish culture at this level of intensity. Average un-ionized ammonia nitrogen concentrations ranged from 20 to 67 μgh⁻¹ and average daily maxima ranged from 63 to 183 μgh⁻¹. Gill lesions characteristic of un-ionized ammonia exposure were common in fish from all ponds.     

Influence of pH on Ammonia Accumulation and Toxicity in Halophilic, Methylotrophic Methanogens

We studied the effects of pH and ammonia concentration on the growth of three methanogens. These three halophilic, methylotrophic methanogens, Methanolobus bombayensis, Methanolobus taylorii, and Methanohalophilus zhilinaeae, grew at environmental pH ranges that overlapped with each other and spanned the pH range from 7.0 to 9.5. During growth they had reversed membrane pH gradients ((Delta)pH) at all pH values tested. The (Delta)pH was in the range of -0.4 to -0.9 pH units, with the cytosol being more acidic than the environmental pH. Methanohalophilus zhilinaeae had the most negative (Delta)pH (-0.9 pH units). These negative pH gradients resulted in the accumulation of ammonium (NH(inf4)(sup+)), and when grown at the highest external ammonia concentrations that allowed good growth, cells had cytosolic NH(inf4)(sup+) concentrations as high as 180 mM. The high concentrations of cytosolic NH(inf4)(sup+) were accompanied by greater (Delta)pH and lower concentrations of the major cytosolic cation K(sup+) (compared with cells grown in medium with only 5 mM ammonia). Methanolobus bombayensis and Methanolobus taylorii were more sensitive to total external ammonia at higher external pH values, but the inhibitory concentration of un-ionized ammonia that resulted in a 50% reduction of the growth rate was about 2 to 5 mM, regardless of the pH. This is consistent with growth inhibition by ammonia in other bacteria. However, Methanohalophilus zhilinaeae was more resistant to un-ionized ammonia than any other known organism. It had a 50% inhibitory concentration for un-ionized ammonia of 13 mM at pH 8.5 and 45 mM at pH 9.5. We examined the effects of pH on three ammonia-assimilating activities (glutamine synthetase, glutamate dehydrogenase, and alanine dehydrogenase) in cell lysates and found that the pH ranges were consistent with the observed ranges of intracellular pH.     

THE INFLUENCE OF CARBON DIOXIDE ON THE TOXICITY OF UN-IONIZED AMMONIA TO RAINBOW TROUT (SALMO GAIRDNERII RICHARDSON)

The toxicity of solutions of ammonia to fish in different dilution waters showed a variation which was not entirely related to the concentration of the un-ionized ammonia molecule. Evidence is presented which shows that this variation can be attributed to the increase in the concentration of free carbon dioxide at the gill surface, which causes a decrease in both the pH value and the concentration of unionized ammonia present; the extent of the decrease depends on the initial concentration of free carbon dioxide in the bulk of the solution. Quantitative measurements of the relation between the free carbon dioxide concentration of the water and the toxicity of un-ionized ammonia are correlated with a theoretical estimation of the pH value of the water at the gill surface.     

Some factors affecting the respiration of some aquatic plants

Summary The oxygen consumption of four aquatic plants has been determined at various concentrations of dissolved oxygen and at three different temperatures.Oxygen consumption rates (mg oxygen/g dry weight per hr) at 20°C in air-saturated water were Berula erecta, 1.25; Callitriche obtusangula, 2.8; Hippuris vulgaris, 1.96; and Ranunculus pseudofluitans, 1.90.Oxygen consumption rates increased with increase in dissolved-oxygen concentration within the experimental limits of 1.2–17 p.p.m. dissolved oxygen. The relation of oxygen consumption to this range of oxygen concentrations can be described by the empirical equation R = aC ^b. Increase of temperature has been shown to increase the rates of oxygen consumption. Q₁₀ values ranging from 1.32 to 3.48 have been obtained.     

Chronic toxicity of ammonia to juvenile gilthead seabream Sparus aurata and related histopathological effects

Effect of 20 days exposure of juvenile gilthead seabream ( Sparus aurata ) to elevated levels of ammonia on growth and survival was examined in a continuous flow system. Suppressed growth and reduced survival were observed at concentrations of 8.2 and 13 mg l⁻¹ total ammonia-N (0.5 and 0.7 mg l⁻¹ un-ionized ammonia-N, respectively) and higher. The maximum acceptable toxic concentration (MATC) for growth was between 4.8 to 8.2 mg l⁻¹ total ammonia-N (0.3 and 0.5 mg l⁻¹ un-ionized ammonia-N, respectively). Fish exposed to high ammonia levels (13 mg l⁻¹ total ammonia-N, 0.7 mg l⁻¹ un-ionized ammonia-N) displayed clear signs of liver pathology. Existing evidence suggests that S. aurata is less sensitive to ammonia than other reported marine and freshwater fish.
Under certain conditions ammonia concentration in the intensive fish ponds in Eilat may exceed the no observed effect concentration for S. aurata .     

Environmental factors influencing survival of threespine stickleback (Gasterosteus aculeatus) in a multipurpose constructed treatment wetland in southern California.

Survival of the threespine stickleback, Gasterosteus aculeatus, differed among marshes in a demonstration 9.9-ha multipurpose constructed treatment wetland designed to improve the quality of secondary-treated municipal wastewater in southern California. At a mean loading rate of 3.3 kg NH4-N ha(-1) d(-1) (6 kg total N ha(-1) d(-1)), the suitability of the wetland to support a population of sticklebacks was estimated to be low. The development of potentially toxic levels of un-ionized ammonia, particularly during periods when pH increased concomitantly with oxygen generation by phytoplankton biomass > 300 mg chlorophyll a liter(-1), and disinfection by-products were associated with lowered survivorship of sentinel fish. Moreover, the high oxygen demand from nitrification of NH4-N created daily periods of low dissolved oxygen concentration (6-16 h at < 2 mg liter(-1)) in the open water areas of the shallow marshes. Low dissolved oxygen concentration in open water zones of the seven marshes during a part of each day and persistent anaerobic conditions in the emergent vegetation rendered the majority of the wetland's substrate surface unavailable for successful reproduction by sticklebacks. The potential sites for Gasterosteus to replace mosquitofish, Gambusia affinis and G. holbrooki, as a biological control agent against mosquitoes are probably limited to comparatively cool-water habitats with high water quality, such as riverine wetlands.     

丁香油在鳊模拟保活运输中的效果

文章研究了丁香油对鳊(Parabramis pekinensis)保活运输的影响。在单因素试验的基础上通过正交试验确定了最佳保活运输条件。并检测和分析了在模拟运输试验中水质指标和鱼体生化指标的影响。结果显示, 最佳保活运输条件为麻醉液浓度15 mg/L、水温9℃和鱼水质量比1﹕3时, 保活时间最长达50h, 且鱼体成活率为100%。在水体指标中, pH和溶氧量无显著变化, 麻醉组氨氮在48h内由0.049增加至4.034 mg/L, 水中微生物在24h内显著增加, 氨氮的增加和微生物的生长会影响鱼体的保活。在鱼体生化指标中, 麻醉组肌肉中糖元含量24h内显著下降, 乳酸含量先升后降, pH先降再升, 说明在保活运输中糖元消耗产生乳酸; 在鱼体血液指标中, 麻醉组谷草转氨酶(AST)活性, 乳酸脱氢酶(LDH)活性, 尿素和肌酐(CREA)在12h后有所上升, 血糖(GLU)在36h内显著增加(P<0.05), 然后降低; 说明随着保活时间的延长鱼体肝脏和肾脏组织代谢水平受到一定的影响。研究表明, 在鳊麻醉保活过程中, 适当使用丁香油麻醉剂, 有助于延长其保活时间和提高存活率。     

The acute lethal toxicity of mixtures of cyanide and ammonia to smolts of salmon, Salmo salar L. at low concentrations of dissolved oxygen

The survival of Atlantic salmon smolts on exposure to constant concentrations of cyanide and ammonia, singly and together, has been measured under laboratory conditions at a concentration of 5 mgl^-1 of carbon dioxide. The 24-h LC50 values of cyanide and of un-ionised ammonia, in fresh water, were 0·073 mg HCN l^-1 and 0·20 mg NH₃l^-1 respectively at a concentration of dissolved oxygen of 10 mg l^-1, and 0·024 mg HCN l^-1 and 0·08 mgNH₃l^-1 respectively at a concentration of dissolved oxygen of 3·5 mg l^-1. In 30% sea water the corresponding values were similar for cyanide but markedly higher for ammonioa. In 80% sea water the values were intermediate between those of fresh water and 30% sea water. Prior acclimation of the fish to the respective toxicant increased the resistance of the fish only slightly to cyanide, but with ammonia the 24-h LC50 was increased between 1·4 and 2-fold after acclimation for 1–3 days to between 0·2 and 0·5 of the 24-h LC50 value. Mixtures of cyanide and ammonia were between 0·6 and 1·25 times as toxic as expected, assuming simple additivity of toxicity.     

氨氮对软体动物生长的影响:以铜锈环棱螺为例

为探究氨氮对底栖动物的毒性效应,在位于湖北保安湖的近自然生态系统(单个水域面积约600 m²,水深约1.5 m)中开展了为期1年的模拟实验,分析了6个不同氨氮浓度[N25>N20>N15>N10>N5>N0(对照);0.2—33.7 mg/L]条件下,大型底栖动物(软体动物)群落特征的差异。结果表明:(1)实验系统中采集的软体动物主要为铜锈环棱螺(Bellamya aeruginosa);(2)从B. aeruginosa密度来看, N0、N5、N10和N15处理相差不大[28(0—85) ind./m²],均显著高于N20和N25处理[5(0—29) ind./m²](P<0.05);(3)从B. aeruginosa生物量来看,N0、N5、N10、N15和N20处理相差不大[40.0(0—85.5) g/m²],均显著高于N25处理[0.8(0—4.0) g/m²](P<0.05);(4)从B. aeruginosa壳长、壳宽和带壳...     

THE BIOLOGICAL OXIDATION OF SPENT GAS LIQUOR

SUMMARY: Mixed cultures of bacteria grown in spent gas liquor readily oxidized phenol, o -, m - and p -cresol, catechol, 3-methyl catechol, 4-methyl catechol, resorcinol, 2-methyl resorcinol, and 4-methyl resorcinol. Quinol, pyrogallol and phloroglucinol were more resistant. The optimum temperature was 30° and the best pH range 6·5–7·8. Yeast extract and sterile sewage sludge both increased the rate of growth of organisms in liquor when the inoculum was small. Five phenol oxidizing organisms were isolated in pure culture. Copper in concentrations greater than 1 p/m inhibited both growth and phenol oxidation by one of these.
Mixed cultures grown in an ammonium thiocyanate medium originally inoculated with Thiobacillus thiocyanoxidans oxidized potassium thiocyanate and sodium thiosulphate. Chloride inhibited thiocyanate oxidation in concentrations above 5,000 p/m, although adaptation to 15,000 p/m was possible. Phenol inhibited thiocyanate oxidation in concentrations of 300 p/m or more. Mixed cultures grown on sodium thiosulphate oxidized sodium trithionate and tetrathionate, potassium pentathionate and hexa-thionate, and potassium and ammonium thiocyanate
Manometric determinations of the 5 day biological oxygen demand of effluents after treatment showed good agreement with the values obtained by the conventional method, the manometric values being usually somewhat higher.     

An intelligent sensor system for the determination of ammonia using flow injection analysis

An intelligent automated ammonia monitoring system was developed based on a commercial ammonia selective electrode used in flow injection analysis (FIA) mode. A prototype automatic monitoring system was produced and interfaced to an IBM personal computer. The interfacing involved the design and fabrication of a sensor interface, an inter-integrated circuit (I²C) card and a flow injection analysis controller. This ammonia monitoring system will be used in conjunction with the dissolved oxygen and temperature sensors for the determination of ammonia toxicity. Use of a sodium hydroxide reagent line allowed determination of total ammonia (un-ionized (NH₃) + ionized (NH₄⁺)). With the output of the pH and temperature probes, un-ionized ammonia can be determined based on an equilibrium calculation. This experimental system was controlled under an expert system, Crystal. It provides the knowledge of equipment setup, control and results interpretation based on the rules stored in its knowledge base.     

The effect of dissolved oxygen and salinity on the toxicity of ammonia to smolts of salmon, Salmo salar L.

The survival of Atlantic salmon smolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air-saturation value, the 24-h LC50 of un-ionised ammonia is 0.15 mg NH₃1⁻¹ in fresh water (hardness 264 mg 1⁻¹ as CaCO₃) and 0.3 mg NH₃1⁻¹ in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1⁻¹ in fresh water and 3.1 mg 1⁻¹ in 30% sea water, the 24-h LC50 is 0.09 mg NH₃ 1⁻¹ and 0.12 mg NH₃ 1⁻¹ respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.     

Transient responses of hybridoma metabolism to changes in the oxygen supply rate in continuous culture

Oxygen is an important nutrient that may limit the productivity of commercial cell culture reactors. The transient responses of hybridoma growth and metabolism to step changes in the oxygen supply rate have been examined for dissolved oxygen concentrations (DO) ranging from 0.1% to 10% of air saturation in continuous culture. Metabolic quotients are reported for glucose, lactate, ammonia, oxygen, glutamine, alanine and other amino acids. A majority of the estimated ATP production was due to oxidative phosphorylation under all conditions tested. Decreases in the oxygen supply rate below the value required to maintain 0.5% DO caused the viable cell concentration to decrease. Glycolysis was enhanced at the lower oxygen concentrations, and after an initial decrease, the specific glutamine consumption rate was also higher. High residual glutamine concentrations occurred below 0.5% DO. Oxidation of other amino acids and production of serine were also inhibited. The cells subsequently adapted to low oxygen concentrations. The increase in cell concentration following the return to 10% DO was preceded by increased biosynthetic activity, as evidenced by transiently reduced yields of lactate from glucose, and alanine and ammonia from glutamine.     

AN INVESTIGATION INTO THE CAUSE OF THE SPONTANEOUS AGGREGATION OF FLAGELLATES AND INTO THE REACTIONS OF FLAGELLATES TO DISSOLVED OXYGEN : PART II.

Spontaneous aggregations of flagellates are formed under the cover-glass because the organisms are attracted to and remain in regions where the concentration of dissolved oxygen is less than the saturation concentration under atmospheric partial pressure. These regions of lessened oxygen content arise towards the center of the liquid beneath the cover-glass, owing to the oxygen consumed by the flagellates in respiration not being replaced here by the solution of atmospheric oxygen, as it is along the edges of the liquid. The flagellates, however, are insensitive to the attraction of regions of lessened oxygen concentration when the oxygen concentration throughout the liquid is above a certain value. Therefore, for the aggregations to form, either the initial concentration of dissolved oxygen must be below this limiting value, or an interval of time must first elapse after the making of the preparation until the respiration of the organisms has reduced the oxygen concentration throughout the liquid down to this limiting value. The aggregations will then form because the flagellates have become positively chemotropic to the lower concentration of oxygen at the center of the liquid. Once established, such an aggregation of flagellates does not remain long in the same form. An area free from flagellates appears at the center of the aggregation so that the organisms lie in a circular band surrounding the clear area. The latter increases in size and its bordering band of flagellates in diameter, the band gradually becoming less circular and more square in shape, if the cover-glass is a square one. The clear central area is a region where the oxygen consumption of the flagellates has reduced the oxygen content to such a low value that the organisms are forced to leave the region. They collect in a band where the concentration of dissolved oxygen is an optimum for them. It is the equilibrium position between the oxygen consumed at the center and that diffusing in from the edges of the liquid. As the consumption at the center is more rapid than the replacement from the edge, the flagellate band moves outwards until it becomes stationary at a position where the rates of consumption and replacement of oxygen are equal. Although the flagellates collect in this manner in regions of optimum oxygen concentration, yet greater concentrations of dissolved oxygen have no injurious effect on them. Concentrations of dissolved oxygen lower than the optimum have the effect of inhibiting the movement of the flagellates. They recover their activity, however, immediately they are given access to dissolved oxygen again. Work done in the past on chemotropism of flagellates will have to be revised in the light of the above facts, since the oxygen content of solutions used has never been taken into account.     

THE TOXICITY OF ZINC SULPHATE TO RAINBOW TROUT

The toxicity of zinc sulphate to rainbow trout ( Salmo gairdnerii Richardson) has been investigated in waters of different chemical and physical properties.
Zinc sulphate was less toxic to rainbow trout in hard water than in soft water; when the log concentration of zinc was plotted against log median period of survival of the fish the dose response curve was linear in a very soft water, and curvilinear in a hard water, approaching an apparent threshold concentration. Solutions of zinc sulphate containing calcium chloride were less toxic than those containing an equivalent concentration of calcium as bicarbonate.
An increase in temperature decreased the survival time of rainbow trout in solutions of zinc sulphate in a hard water, but the threshold concentration was not appreciably affected by changes in temperature.
A reduction in the dissolved oxygen concentration of the water increased the toxicity of zinc sulphate, but the effect was reduced when the fish were previously acclimatized to the lower oxygen concentration of the test.
The cause of death of fish in solutions of zinc sulphate was not by the precipitation of mucus on the gills but probably by damage to the gill epithelium.     

Animal chamber for in vivo testing of toxic gases

A closed-circuit chamber system for exposing animals to toxic concentrations of oxygen or nitrogen was designed and built. The facility was equipped with systems for the removal of carbon dioxide, ammonia, methane, water vapor, and particulates from the gas stream. Integral systems were built to monitor and control temperature (+/- 1 degree C), relative humidity (+/- 2%), oxygen concentration (10 to 100% +/- 0.5%), and methane concentration (below 2%). Operation was set at standard pressure (1.0 X 10(5) Newtons/m2). Hyperoxic studies have been performed on six species of rodents, as well as sheep, and have lasted from 1 to 28 days.     

Aerobic microbial growth at low oxygen concentrations

Sterilizable membrane probes were used to study the relation between oxygen concentration and respiration rate in Candida utilis growing on acetate. When the organism was grown in a continuous fermentor at various dissolved oxygen concentrations (0.23 x 10(-6) to 32 x 10(-6)m), with time allowed for full adaptation to each oxygen concentration, the relationship between oxygen concentration and growth rate simulated Michaelis-Menten behavior, giving an apparent K(m) for oxygen of 1.3 x 10(-6)m. When respiration rate was measured at various oxygen concentrations without allowing time for adaptation, it was found that the respiration rate was directly proportional to O(2) concentration at low O(2) concentrations, and independent of O(2) concentration at high O(2) concentrations. Transition from one type of behavior to the other was fairly abrupt. The respiration rate in the presence of excess oxygen depended on the O(2) concentration at which the cells were grown, but the rate at low O(2) concentrations did not. There was evidence that, at low oxygen concentrations, oxygen diffusion through the cell substance limits respiration rate, at least in part.     

Influence of the adipate and dissolved oxygen concentrations on the beta-lactam production during continuous cultivations of a Penicillium chrysogenum strain expressing the expandase gene from Streptomyces clavuligerus

The influence of adipate concentration and dissolved oxygen on production of adipoyl-7-aminodeacetoxycephalosporanic acid (ad-7-ADCA) by a recombinant strain of Penicillium chrysogenum expressing the expandase gene from Streptomyces clavuligerus was studied in glucose-limited continuous cultures. Operating conditions were maintained constant but the adipate and dissolved oxygen concentrations (DOC) were varied separately in a range from 1 to 37.5gl(-1) and from 2% to 125% air saturation (%AS), respectively. The total beta-lactams specific productivity, r(ptotal), was not significantly changed for adipate concentrations from 5 to 25gl(-1), but the flux towards an unknown by-product decreased as the adipate concentration increased. Investigations at different DOC showed that r(ptotal) was stable around 18 micro molgDW(-1)h(-1) for DOC being in the range from 15 to 125%AS. When DOC was decreased from 15 to 7%AS, r(ptotal) increased to 25 micro molgDW(-1)h(-1), mainly due to a two-fold increase in the adipoyl-6-aminopenicillanic acid (ad-6-APA) specific productivity.