A computer-based system for the acquisition and display of continuous vertical profiles of temperature, salinity, fluorescence and nutrients

A vertical profiling system was developed to continuously measure and simultaneously log temperature, salinity, depth, fluorescence and selected nutrient concentrations (NO₃⁻, NH₄⁺, SiO₄⁴⁻ and PO₄³⁻) in the euphotic zone in coastal waters. A hose was attached to a CTD sensor and lowered through the water at 1 m min⁻¹. Water was pumped to the ship's deck with a diaphragm pump, and passed through a fluorometer and Technicon AutoAnalyzer^® to measure fluorescence and selected nutrients, respectively. A 25 m vertical profile takes about 30 min to complete. These instruments were connected to an analog-to-digital converter, and the data were stored and plotted using an IBM personal computer to simultaneously display real-time vertical profiles of temperature, salinity, fluorescence and several nutrient concentrations. This instrument package is invaluable because it provides real-time data that are essential for choosing discrete sampling depths, and for obtaining a time series of the vertical structure of the euphotic zone of dynamic coastal waters or lakes.     

Optimizing experimental design to estimate ammonia and nitrite oxidation biokinetic parameters from batch respirograms

Knowledge of relative NH₄⁺–N to NO₂⁻–N oxidation and NO₂⁻–N to NO₃⁻–N oxidation dynamics is essential before application of either single-step or two-step nitrification models to fit batch nitrification respirograms. We have previously shown that two step nitrification models based on respirometry permit the estimation of kinetic parameters for both nitrification steps from a single respirogram associated with NH₄⁺–N to NO₃⁻–N oxidation. However, two-step model parameter estimates are meaningful only under circumstances when the respirograms contain sufficient kinetic information pertaining to both steps. In this study, we present an operationally amenable extant batch nitrification respirometric assay to engender maximal information content in the resulting respirograms with respect to both constituent nitrification steps. The developed design consists of an initial NH₄⁺–N pulse to a nitrifying biomass sample followed by an additional NO₂⁻–N pulse at an optimal time point, which can be rigorously determined by maximizing the value of the determinant of the Fisher information matrix, Det(F) or, alternatively, by visually identifying the point of NH₄⁺–N depletion during the respirometric assay. The proposed design is applicable for accurate determination of the Monod kinetic parameter estimates for both nitrification steps from batch respirograms even when the pseudo-first order rate coefficients for the two nitrification steps are nearly equal; a condition under which standard NH₄⁺–N to NO₃⁻–N respirograms typically lack information with respect to NO₂⁻–N oxidation.     

Accumulation of nitrous oxide in aerobic groundwaters

N₂O concentrations in the groundwaters collected in the Kanto District and Nagano Prefecture in Japan and five counties in New York State were determined. These N₂O data were obtained from the water samples from wells, springs and seepages from soils in forests and cropping fields. The N₂O concentrations in all samples greatly exceeded those of atmospheric equilibration. The average concentration of 690 nM N₂O is one order of magnitude larger than that in deep ocean. All groundwaters of the present study were aerobic with a high level of NO₃⁻, but with the absence of NO₂⁻ and NH₄⁺, and with a very low level of dissolved organic carbon. These characteristics suggest that the nitrate respiration in the aquifers is of little significance for the production of N₂O.

ΔN₂O/NO₃⁻ molar ratios in the groundwaters were between 10⁻⁴ and 10⁻² (Δ indicates the excess gas over that which would be in equilibrium). This supports the above view since the observed N₂O yield agrees with that reported for the production during an ammonia oxidation. If nitrification was indeed a major mechanism for the production of groundwater N₂O, subsequent release of N₂O from the aquifers that are polluted with nitrogen may deserve more close attention as a potential source of atmospheric N₂O via diffusion and discharge.     

Ammonia oxidation in nitrosomonas at NH3 concentrations near km: Effects of pH and temperature

Nitrosomonas europaea from continuous pure cultures was incubated with 26.4 μ M NH₃(= 0.37 mg NH₃-N l⁻¹) at various NH₄⁺ concentrations, pH values and temperatures. Measured rates of nitrite formation were significantly influenced by pH. Likewise unexpectedly, the maximum ammonia oxidation rate occurred between pH 6.7 and 7.0. Temperature had an even stronger effect on the rate of ammonia oxidation than the availability of NH₃. It is concluded that the assumption of a strict dependence of the rate of ammonia oxidation on substrate concentration is an unjustified oversimplification. Among the mechanisms which could explain ammonium uptake and oxidation near or below pH 7.0, the formation of NO from HNO₂ is considered.     

Growth of Selenastrum capricornutum in natural waters augmented with detergent products in wastewaters

A determination of whether the removal of phosphate builders from detergents would modify the ability of domestic secondary treated sewage effluent to stimulate the growth of a test alga (Selenastrum capricornutum-Printz) in receiving waters alone and augmented with detergent products was made. The lakes used as sources of test waters were located in northeastern New York State and possessed total phosphorus concentrations ranging from ca. 0.01 to 0.04 mg P1⁻¹.

The alga experienced stimulation in all three test lake waters from secondary sewage containing detergent with phosphate or detergent without phosphate. A concentration of 60 μg P 1⁻¹ was sufficient to effect significant algal growth in two of the test waters; however, concentrations ranging up to 110 μg P 1⁻¹ did not generate such a response in the third test water. This latter result and others suggested that neither phosphorus nor other nutrients from these wastewater additions were the factors fully accountable for the observed response(s).     

Combined γ-ray irradiation-activated sludge treatment of humic acid solution from landfill leachate

Humic acid, which is a typical microbially refractory organic substance, was extracted from a landfill leachate. The humic acid solution (COD = 367 mg 1⁻¹; TOC = 293 mg 1⁻¹; BOD = 27 mg 1⁻¹) was applied to a batch scale activated sludge treatment after the modification of its biodegradability by γ-ray irradiation. The BOD increased to 64 mg 1⁻¹ by irradiation of 15 kGy (1.5 Mrad), while the COD and TOC decreased to 231 and 230 mg 1⁻¹, respectively. When the irradiated sample was treated with an activated sludge, the BOD decreased rapidly in 2–3 h to about 15 mg 1⁻¹ which was a similar value as the unirradiated sample was treated. The elimination efficiency of TOC by the sludge treatment was approximately equal to that obtained by irradiation of 15 kGy. These facts suggest a utility of applying microbial processes after radiation treatment of microbially refractory wastewaters.     

Variation of ATP content in Scenedesmus dimorphus cells grown in a chemostat culture and its comparison with chlorophyll-A content

The variations of ATP and chl-a contents in Scenedesmus dimorphus cells grown in a chemostat culture under nutrient limitation were investigated. ATP and chl-a contents per algal dry weight varied in the ranges of 0.15–1.64 μg mg⁻¹ (0.33–3.82 μg mg⁻¹ as ATP/C ratio) and 0.32–1.32% (7.8–30.8 μg mg⁻¹ as chl-a/C ratio), respectively, under the conditions of T-N/T-P ratio of 2–50 by weight and dilution rate of 1–4 per day. At every T-N/T-P ratio, both ATP and chl-a contents increased as dilution rate increased. At a given dilution rate, ATP content decreased systematically as T-N/T-P ratio increased, with the only exception at dilution rate of 4 per day. It was considered based on the result that ATP or chl-a can hardly be used successfully as an indicator of algal biomass.     

Automated fluorometric method for determination of boron in waters, detergents and sewage effluents

An automated method for the determination of boron in natural waters, detergents and sewage effluents is described. The method is based on the reaction of 4'-chloro-2-hydroxy-4-methoxybenzophenone (CHMB) with boron to produce fluorescent species, in a 90% sulfuric acid medium. The method has been made specific to remove any interferences from all major and minor ions and other organic compounds normally present in water. The method is capable of measuring different chemical forms of boron such as boric acid, borax, sodium perborate and tetraphenyl boron. The method analyses 10 samples per hour, in the 5–100 μg 1⁻¹ boron range. The rate of sample analysis can be increased to 20 per hour at higher concentration ranges. The limit of detection is 1 μg 1⁻¹ boron.     

Denitrification studies with glycerol as a carbon source

Based on the results of experimental work, the use of glycerol as a carbon source for denitrification is discussed. Investigations were carried out in modified UASB reactor using a mixed bacterial population in medium containing 600 mg NO₃---N and essential biogens. It was found that at the most favourable C:N RATIO = 1.0 the efficiency of denitrification depended on nitrate load as well as on cell residence time. At nitrate loads in the range 220–670 mg NO₃---Nl⁻¹ day⁻¹ (0.08–0.14 mg NO₃---N mg⁻¹ day⁻¹) nitrogen removal was 0.6–0.12 mg N mg⁻¹ day⁻¹, respectively. Denitrification unit biocenosis was composed of bacteria, fungi and protozoa. The number of denitrifying bacteria per sludge weight unit within the studied range of nitrate loads was constant and averaged 23 × 10⁷ cells mg⁻¹.     

Effect of exposure time and copper concentration on reproduction of the fathead minnow (Pimephales Promelas)

Three concurrent studies were conducted to determine the chronic effect of prespawning exposure to various concentrations of copper on fathead minnow reproduction. Copper was introduced into the three exposure systems to give 6-, 3-, and 0-months exposure prior to spawning. Prespawning exposure time had no significant effect on reproduction. Number of eggs produced per female decreased, however, with increase in copper concentrations. Egg production at copper concentrations of 37μg 1⁻¹ and higher was significantly lower (P = 0.05) than in the control, but at concentrations of 24μg 1⁻¹ and lower it was not different. The maximum acceptable toxicant concentration (MATC) was estimated to be 32μg Cu 1⁻¹, which is 0.07 of the 96h LC₅₀. This application factor for copper is similar to those found in other studies.     

Fish toxicity of jet fuels—I. The toxicity of the synthetic fuel JP-9 and its components

The toxicity of the jet fuel JP-9 and its components RJ-4, RJ-5 and MCH was assessed in static bioassays on the warm water fish, golden shiner (Notemigonus chrysoleucas). The 96-h LC₅₀ of emulsions was 2.0 mg 1⁻¹ for JP-9, 0.51 mg 1⁻¹ for RJ-4, 0.61 mg 1⁻¹ for RJ-5 and 72 mg 1⁻¹ for MCH. As determined by the 96-h LC₅₀ values unemulsified fuel (pools of fuel) JP-9 was 235 times less toxic, RJ-4 was 196 times less toxic, RJ-5 was 7700 times less toxic and MCH was 3.3 times less toxic than the corresponding emulsified materials.

In continuous flow bioassays with the water soluble fraction of the fuel and its components the effect on egg hatchability and fry development of flagfish (Jordanella floridae) and rainbow trout (Salmo gairdneri) was studied. The no effect of level on flagfish egg hatchability was 0.23 mg 1⁻¹ for JP-9 and 0.05 mg 1⁻¹ for RJ-5. Concentrations of 0.83 mg 1⁻¹ MCH and 0.2 mg 1⁻¹ RJ-4 did not affect egg hatchability. In rainbow trout studies 97-day LC₅₀ values for RJ-4 and RJ-5 were 0.045 mg 1⁻¹ and 0.072 mg 1⁻¹, respectively, and 23-day LC₅₀ values for JP-9 and MCH were 0.26 mg 1⁻¹ and 1.3 mg 1⁻¹, respectively.

The accumulation of fuels in fish bodies was studied and it was found that flagfish can tolerate a total body burden of 0.5 mg MCH g⁻¹ wet weight without lethality. It was also found that body burdens of 0.43 mg RJ-4 g⁻¹ and of 0.27 mg RJ-5 g⁻¹ on a wet weight basis will produce 50% mortality in rainbow trout.

Voiding of MCH from fish bodies occurs readily in fuel-free water, but RJ-4 and RJ-5 are retained in the tissues.     

Toxicities of total and chelex-labile cadmium to salmon in solutions of natural water and diluted sewage with potentially different cadmium complexing capacities

The LC₅₀ for total Cd averaged 4.8 and 8.0 μg1⁻¹ in river water and 33% sewage-treatment-plant effluent (STPE), respectively, and for Chelex-labile Cd, 3.9 and 5.6 μg1⁻¹, respectively. The LC₅₀ values for total Cd were significantly (P < 0.05) different, indicating a reduction in toxicity of Cd in the presence of 33% STPE, presumably due to complexation of Cd²⁺. The similarity of LC₅₀ values for Chelex-labile Cd indicates that that fraction contained toxic species of Cd at approximately the same concentration(s) in both river water and 33% STPE; it is therefore considered a better measure of Cd toxicity than total Cd. Furthermore, mortality was correlated with the concentration of Chelex-labile Cd but not with that of Chelex-nonlabile Cd. Measurements of Cd²⁺-complexing capacity by the Chelex method indicated that toxicity was due, at least in part, to Cd²⁺. Values were less than those obtained by the ion-selective-electrode method; these indicated that toxicity was due only to complexed Cd. Values from both methods were uncorrelated with LC₅₀ values.     

Acclimation to and biodegradation of nitrilotriacetate (NTA) at trace concentrations in natural waters

Acclimation to and biodegradation of nitrilotriacetic acid (NTA), an organic builder used in synthetic laundry detergents as the sodium salt, was studied at trace concentrations (ppb) in several river waters. The river waters tested ranged from those where extensive NTA exposure via detergents had not occurred, to those where NTA exposure had been continuous for several years. In rivers not previously exposed to NTA, acclimation and degradation were observed at the lowest initial concentration tested, 5 μg 1⁻¹. Degradation of NTA after acclimation followed apparent first order kinetics, and half lives for NTA removal ranged from 7 to 138 h at initial NTA concentrations of 50 and 5 μg 1⁻¹, respectively. Degradation of NTA in water samples where prior NTA exposure had already occurred required no acclimation and was less variable than in unexposed rivers. First order rate constants varied only slightly over a 1000-fold initial concentration range (1–1000 μg 1⁻¹) and NTA half lives ranged from 7 to 17 h. In general, our results indicate that microflora present in natural waters can acclimate to and degrade NTA, even if exposed to only trace levels in laboratory experiments. However, rates of NTA biodegradation are more rapid and less variable in river waters where natural NTA exposure has already occurred.     

On the reoxygenation efficiency of diffused air aeration

One technique used to increase the dissolved oxygen concentration of polluted waters is the bubbling of air through a diffuser pipe located at depth, thereby producing a bubble curtain from which oxygen transfer to the water occurs.

The results of laboratory studies on the aeration efficiency of a diffuser placed along the entire width of a flume, perpendicular to a cross flow are presented (two dimensional aeration). Parameters investigated include (1) diffuser type-porous materials with mean pore sizes of 40, 90 and 180 μm and perforated pipes with 0.4, 0.6 and 1.0 mm diameter ports (2) air flow rate per unit width 3–53 m³ (m h)⁻¹ and (3) cross flow velocity (2.5–15 cm s⁻¹. The effect of variation from the two dimensional situation is also discussed as well as the consequence of using oxygen instead of air, and the sensitivity to discharge angle, port spacing and the free surface. The measured efficiencies are compared with theory as well as available laboratory and field data.

The major conclusions are (1) aeration efficiencies using diffused air aeration are on the order of 2–13%m⁻¹ (2) the aeration efficiency increases with increasing cross flow velocity and decreasing air flow rate per unit width (3) aeration efficiencies using porous filters, for air flow rates less than 40 m³ (m h)⁻¹, are significantly higher (a factor of 2–3) than those achieved using perforated pipes (4) changing the pore size from 40 to 180 μm, the port size from 0.4 to 1.0 mm or the port spacing does not significantly effect the aeration efficiency (5) aeration using oxygen is somewhat less efficient than that using air. However, since equivalent oxygen bubbles contain approximately five times more oxygen than air bubbles, more oxygen is transferred on an absolute basis at the same gas flow rate using compressed oxygen as opposed to air (6) aeration efficiency resulting from aeration over a portion of the entire width can be reasonably predicted using the results of the two dimensional studies and (7) the available laboratory and field data compare well with the results of these laboratory studies.     

Denitrification rates in relation to stream sediment characteristics

Potential rates of nitrate removal were studied in sediments from three Ontario rivers that differed in texture, organic carbon contents and other characteristics. Intact 0–5 cm depth sediment cores from 22 sites on each river were overlain with aerated 5 mg 1⁻¹ NO₃⁻-N solution and incubated in the laboratory at 21°C for 48 h. Rates of nitrate-N loss from the overlying solutions varied from 37 to 412 mg m⁻² day⁻¹ for a 24 h incubation period. The acetylene blockage technique was used with nitrate amended sediments to evaluate the relative importance of denitrification and nitrate reduction to ammonium. Denitrification accounted for 80–100% of the nitrate loss in the majority of sediment samples tested. Rates of nitrate loss for the 24 h period exhibited a highly significant positive correlation (r = 0.82–0.89) with the water-soluble carbon content of the sediments in each river. Significant relationships were also observed between nitrate loss and organic carbon, total nitrogen and sediment ammonium. A decline in nitrate loss via denitrification and increased nitrate reduction to ammonium was correlated with the organic carbon and water-soluble carbon content of the stream sediments.     

Mechanisms and products of ozonolysis of aniline in aqueous solution containing nitrite ion

The presence of nitrite ions (1 × 10⁻⁴ M) in the reaction medium affected the aqueous reaction of aniline (1 × 10⁻⁴ M) and ozone (2.07–2.15 × 10⁻⁴ M) at pH 6.25–10.65; o-, m- and p-nitroaniline were formed in addition to reaction products reported earlier. The combined yield of o- and p-nitroaniline was as high as 8%. Their yields were significantly higher at pH 6.25 and 7.25 than at pH 10.65 and carbonate species-inhibited their formation. The reaction mechanisms for the formation of the nitroanilines involves pernitrous acid, hydroxyl radical and nitrogen dioxide radical as the important intermediates.     

Toxicity of chlorine to juvenile spot, Leiostomus Xanthurus

The sensitivity of juvenile spot, Leiostomus xanthurus, to total residual chlorine (TRC) in flowing sea-water was investigated. Incipient LC₅₀ bioassays, histopathology, avoidance tests and the combined effect of thermal stress and TRC were used to assess sensitivity.

Estimated incipient LC₅₀ values were 0.12 mg 1⁻¹ TRC at 10°C and 0.06 mg 1⁻¹ TRC at 15°C. Histological examination of spot used in the incipient LC₅₀ bioassay at 15°C and sacrificed while alive indicated pseudobranch and gill damage occurred in individuals exposed to a measured TRC concentration of 1.57 mg 1⁻¹. Spot exposed to lower concentrations of TRC, 0.02 0.06 mg 1⁻¹ at 15°C and sacrificed alive showed no consistent tissue damage.

Spot demonstrated temperature dependent avoidance responses to TRC. At 10°C, a concentration of 0.18 mg 1⁻¹ was required for significant (X²; P < 0.05) avoidance; at 15 and 20°C, spot showed significant avoidance of TRC concentrations as low as 0.05 mg 1⁻¹.

Simultaneous exposure of spot to thermal stress (5, 10 or 13°C above the acclimation temperature of 15°C) at measured TRC concentrations of 0.05 0.07 and 0.34–0.52 mg 1⁻¹ demonstrated a significant, (Z²) with Yates correction, P < 0.05) increase in sensitivity to TRC with increased temperature and exposure times for some of the groups tested.     

Removal of cadmium and manganese by a non-toxic strain of the freshwater cyanobacterium Gloeothece magna.

The ability of both living and dry cells of Gloeothece magna, a non-toxic freshwater cyanobacterium, to adsorb cadmium and manganese is demonstrated in this study. Chlorophyll a content of living cells was not influenced by either cadmium or manganese concentrations, indicating that adsorption of both Cd²⁺ and Mn²⁺ by living cells of G. magna, was independent of the metabolic state of the organism. Moreover, the adsorption of both Cd²⁺ and Mn²⁺ to living cells and dry cells, was dependent on the metal concentrations, and fitted the Freundlich adsorption isotherm. However, dry cells had larger binding capacity for both Cd²⁺ (K_f=912.6) and Mn²⁺ (K_f=2398) than living cells (K_f=151.4 & 63, respectively). The role of the capsular polysaccharides, the main constituents of the cyanobacterial envelope, in binding these two metals was also studied. Polysaccharide extracts of this organism adsorbed high amounts of both Cd²⁺ (115–425 μg mg⁻¹) and Mn²⁺ (473–906 μg mg⁻¹). This study suggests that G. magna would probably be cultured in water bodies contaminated by heavy metals to ameliorate their toxicity. Also dry material of this cyanobacterium being a non-toxic species, could be used as a safe biofilter to remove toxic metals from drinking water.     

Study of tropaeolin degradation by iron--proposition of a reaction mechanism

The degradation of tropaeolin by iron was studied under oxidizing and inert atmospheres. The products were identified by various chromatographic and spectroscopic methods. Under inert atmosphere, the proposed model of mechanism is based on the adsorption of tropaeolin by the sulfonate function on the solid iron, followed by a reduction of the –N=N– bond with formation of 1-amino-2-naphthol and sulfanilic acid. These two intermediaries were reduced to 1,2-dihydroxynaphthalene and benzene with NH₄⁺ and HSO₃⁻ liberation. Under oxidizing atmosphere, besides the reductions of tropaeolin, water and ferric ions, the existence of a homogeneous degradation was found. This process was explained (on the basis of surface iron potential monitoring) by a stepwise reduction of oxygen giving hydrogen peroxide. The initial stages of the mechanism were similar to those under inert atmosphere, but the degradation of the 1,2-dihydroxynaphthalene continued giving 1,2-naphthalenedione, then various polar monocyclic compounds leading to three unidentified volatile final products.     

Effect of electrolyte composition, and of added iron(III) in the presence of selected organic complexing agents, on nickel(II) precipitation by lime

The effect of effluent composition involving the common anionic species Cl⁻, SO₄²⁻ and CO₃²⁻ on the efficiency of nickel(II) precipitation, modelling lime (CaO) as the precipitant, has been investigated using the solubility domain approach. Solubility domains were based on the phases that were found to limit metal solubility for systems representing potential effluent composition limits. These phases were found to resemble their mineralized counterparts, but with a lower degree of structural order. At higher SO₄²⁻ and CO₃²⁻ concentrations both gypsum (CaSO₄·2H₂O) and calcite (CaCO₃) were formed, but these had little effect on the observed residual nickel solubility. The calculated solubility domains were found to generally encompass the experimentally determined solubilities, thereby providing quality assurance ranges for hydroxide precipitation. The effect of the complexing anions tartrate and EDTA⁴⁻ on residual Ni(II) in solution as well as the effects of the addition of Fe(III) on the removal of Ni(II) complexed by these species are described.