Test Jar Research Articles

Health Risk Assessment for Reused Backwash Water from Saveh Water Treatment Plant

Background: The increase in population growth, industries and living standards have caused an increasing need for drinking water in many countries. The reuse of treated water and wastewater is one of the most important options to deal with water shortage. To ensure the correctness of this work, it is necessary that the health risk assessment be reassessed during use so that consumers do not face serious problems. In this regard, the assessment of health risks assessment for the water recovered from the backwashing wastewater of the Saveh water treatment plant was investigated. Methods: To reuse the backwash wastewater from the Saveh water treatment plant, the processes of primary sedimentation and coagulation (in the form of a test jar) were investigated. Metals and heavy metals like iron (Fe), aluminum (Al), lead (Pb), Arsenic (As) and cadmium (Cd) were examined to evaluate health risks. The initial settling time was 1 hour, the coagulant used was FeCl3 made in Iran, and heavy metal contents were also measured with an Inductively coupled plasma (ICP) device. Results: The value of HRIs for Al, Fe, As, Pb and Cd in the treated spent filter backwash water (SFBW) with primary sedimentation and coagulation was less than "1" and indicates the absence of risk. Conclusion: The treated backwash wastewater treated with primary sedimentation and coagulation processes as well as raw water of the Saveh have no harmful effects in terms of heavy metals, and its reuse will not pose a risk to the health of the consumer.

The effect of climbing film on molybdenum disulfide nanosheets flooding in the tertiary oil recovery

With the development of nanotechnology, nanomaterials have shown good potential for enhanced oil recovery, which is of great significance for oil and gas production. Compared with nanoparticles and nanoemulsions, nanosheets have higher interfacial activity due to their two-dimensional structure, which can form a climbing film on the interface of oil-water and efficiently improve oil recovery. However, the influencing factors of the film-climbing effect and the relationship between the film-climbing effect and enhanced oil recovery are still not clear.In this paper, small-sized water-soluble nanosheets which were molybdenum disulfide (MoS2) nanosheets (30–50 nm) were synthesized using a one-step hydrothermal method, which have strong stability during the flooding test. And then, modifiers with different carbon chain lengths were used to modify the hydrophile-lipophile balance (HLB) of nanosheets.Next, the influencing factors of nanosheets' climbing film were discussed, and the two-phase height index was innovatively used to characterize the strength of the nanosheets climbing film in the oil-water system. The results show that the longer the carbon chain length of the modifier, the closer the nanosheets are to neutral wet with stronger interfacial activity. In addition, molybdenum disulfide nanosheets can produce a climbing film at the oil-water interface, which is related to salinity, concentration, and diameter of test jar. In a word, the oil displacement efficiency can be characterized by the two-phase height index, and the higher the index, the higher the oil displacement efficiency. This makes us fully realize the importance of climbing film in tertiary oil recovery, and provides a new method for the effective development of oil and gas resources.

Kinetika Reaksi Resin Immobilized Photocatalyst Technology (RIPT) TiO2 Sebagai Bahan Alternatif Pengolahan Limbah Cair Tahu

Liquid waste from the tofu industry contains a lot of organic matter, the high content of this organic material will result in high BOD and COD values ​​in the waters and can have a bad impact if not handled properly. One alternative that is commonly used to overcome this problem is to use a photocatalyst degradation method. This study aims to determine the reaction kinetics which includes the determination of the reaction rate constant and the reaction order in removing the COD content of the resin-immobilized TiO₂ photocatalyst. This study presents the reaction kinetics of RIPT with catalyst, TiO2, catalyst mass (10gr, 20gr, 30gr), and RIPT mass (5gr, 10gr, 15gr). This research was conducted by making immobilized TiO2 photocatalyst resin and then entering 1000 ml of tofu industrial waste and the obtained RIPT-resin into the reactor in which stirring occurred using a test jar. Based on the results of the study, the best value for the reaction rate constant was obtained by the mass variation of RIPT (15gr). Meanwhile, the best value constant of reaction rate was obtained by mass variation of 30 gram TiO2 catalyst, with the result that the reaction rate constant value of RIPT- and RIPT-TiO2 30 grams was 0.0101 minute-1.

Impact of volatile organic compounds (VOCs) from acrylic double-sided pressure-sensitive adhesives (PSAs) on metals found in cultural heritage environments

An artificial aging protocol known as the Oddy test was combined with headspace solid phase micro-extraction (SPME) gas chromatography-mass spectrometry (GC–MS) data to identify which of 17 double-sided acrylic pressure-sensitive adhesives (PSAs) were safest to use in cultural heritage environments. Traditional Oddy testing showed every PSA corroded lead coupons while 1 also corroded copper and silver coupons. 10 PSAs were suitable for short-term use near cultural heritage artifacts while the remaining 7 were unsuitable. An adapted Oddy test identified whether several known acrylic-based adhesive precursor chemicals, including ethyl acrylate, n‑butyl acrylate, 2-ethylhexyl acrylate, acrylic acid, and abietic acid caused the observed corrosion. Lead coupons were extremely sensitive to acrylic acid, with a 5 × 10−5 mg L-1 Oddy test jar concentration capable of initiating corrosion at 60 °C and 50% RH. SPME GC–MS showed that any evidence of acrylic acid or acetic acid with peak areas larger than 19 million were both markers for unsuitable PSAs. 2-ethylhexyl acrylate was less reactive to metals though a GCMS peak area greater than 200 million was correlated with unsuitable PSAs. 3M™ 465, 3M™ 908, and Tesa® 88,250 tapes were concluded to be the best double-sided PSAs for use in cultural heritage environments.

Coagulant dose as an operating parameter in a solid contact clarifier

Abstract The objective of this study was to determine the applicability of the laboratory flocculation test (Jar Test) for a solid contact clarifier. Cohesivity, a parameter characterizing the sludge blanket can be established by determining the Sludge Cohesion Coefficient (SCC) by conducting a Sludge Cohesion Test (SCT). A series of laboratory tests were performed using the Jar Test and SCT. Considering the large number of variable parameters involved with natural raw water, sludge samples were prepared using synthetic raw water with varying turbidity and coagulant dose combinations. A comparison was made between the optimum coagulant dose obtained using the two tests. Highest SCC observed at the optimum coagulant dose was within the range of 0.6–3.3 m/hr. Low SCC values indicate a light and fragile sludge blanket whereas high SCC values indicate a quick settling consistent blanket. With increasing raw water turbidity, the optimum coagulant dose given by SCT is lower than that of the Jar Test. Hence, at higher raw water turbidity occurrences, it may be possible to operate the upward flow solid contact clarifiers with lower coagulant dose. A significant quadratic relationship is observed between the optimum coagulation doses with R2 = 0.9 and α < 0.05.

Perbandingan Kebutuhan Koagulan Al2(So4)3 dan PAC Untuk Pengolahan Air Bersih Di WTP Sungai Ciapus Kampus IPB Dramaga

Water Treatment Plant (WTP) IPB process water from Ciapus River by water purifying process before distributed to consumers. The type of coagulant used is Al2(SO4)3 (aluminum sulfate) or alum and Polyaluminium Chloride (PAC). This study aimed to compare the water quality by using coagulant Al2(SO4)3 and PAC in WTP Ciapus River IPB Dramaga and to find out the optimum dosage of coagulant alum and PAC . This study used a test jar method and ISO (SNI) for the analysis of physical and chemical parameters of water. Based on the results of research, PAC was better than alum with the optimum dose of 20 ppm which produces 0.22 NTU of turbidity, 1 mg/l of TSS and 150 mg/l of TDS. While the optimum dose of alum was 20 ppm which generates 0.49 NTU of turbidity, 0 mg/l of TSS and 164 mg/l of TDS. Average costs for the use of coagulant alum and PAC were Rp. 95/m3 and Rp 215/m3, while the average value of the efficient used of coagulant alum and PAC were 91.34% and 83%. The results of both coagulants meets the criteria of water quality standards in accordance with Regulation of the Minister of Health No. 429 of 2010.

Physicomechanical Characterization of Basement Rocks for Construction Aggregate: A Case Study of Kajuru Area, Kaduna, Nigeria

This study evaluates the physical, mechanical and in-situ properties of the rock aggregates in Kajuru, Kaduna State, Nigeria as sources of aggregate for construction purpose. The uniaxial compressive strength was determined by using Universal Testing Machine to crush cored samples and Schmidt rebound number by Schmidt hammer apparatus. While the engineering destructive tests were carried out on aggregates using various apparatus. Na2SO4 solution was used for soundness test and glass jar for determination of specific gravity. The results indicate that specific gravity ranges from 2.48 to 2.88, the moisture content of samples are within 2%. The UCS ranges from 95.76Mpa to 169.70Mpa while the Schmidt rebound number ranges from 29.4 to 35.3. Comparing the Los Angeles abrasion, impact and crushing value obtained from the laboratory destructive test with the B.S standards, most of the rock can be used for construction works. The results also indicate that there is direct proportional relationship between compressive strength with Schmidt rebound number and specific gravity. Inverse relationship exists between moisture content with specific gravity and compressive strength. The physical and geotechnical properties were found to be dependent on the chemical and petrographic characteristics of the rock. This paper exhibit the geotechnical and physical properties of rock as the second part of the research on Characterization of Basement Rocks in Kajuru area, Kaduna, Nigeria for Construction Aggregate. Kaduna is located on a basement rock that is widely used as construction materials for highways, bridges, dams, rail tracks and buildings. The excessive excavation of river sand is becoming a serious environmental problem (Jayawardena and Dissanayake, 2008) that leads to failure of river banks, lowering of river beds, damages to bridge foundations and other structures situated closer to the rivers. Similar trend is obtainable in northern Nigeria. Therefore rocks are also quarried for manufacture of quarry dust and are used as sand replacement for construction purposes and moulding of bricks. They are also used as granite and marble for production of magnificent walls, floor tiles and grandeur kitchen tops etc. In the various ways rock aggregates are used, they are exposed to a variety of stresses, and the response of the structure in which it is used will largely depend on the properties of the aggregate. It needs to resist heavy loads, high impacts and severe abrasion, and it needs to be durable in the prevailing environmental condition (Egesi and Tse, 2012). This study was initiated from the observation that there are variations in properties and strength of rock and aggregate obtained from one geological location to the other. Therefore it is imperative to systematically characterize aggregates obtained from this area and evaluate factors that control the compressive strength of rock in order to develop practical quality-control specifications and ease optimum aggregate selection. The present study aims to highlight the basic engineering properties of aggregates source rock and integrate factors controlling them from this area. II. Materials and Methods Gamin76 (GPS) was used to survey the drill holes locations and their coordinates were recorded in the field work book. Cored rocks were obtained from 12 different drills holes spread across the research area at depth ranges from 12m to 15m. Samples collected at 5m depth intervals were placed in polythene bag which were accurately labelled for uniaxial compressive strength test. Large boulders were obtained from rock outcrops in situ and these outcrops were crushed into smaller sizes by local crusher to determine the physical properties. Specific gravity and water absorption rate were measured using weight balance, oven and glass jar. Destructive test of impact and crushing value was carried out using their apparatus. Los Angeles abrasion test was done with abrasion testing machine while Na2SO4 solution was used for soundness test. Bulk samples taken from the specimens were also cut into blocks for Schmidt hammer test.

Does Stone Entrapment With "Uro-Net" Improve Ho:YAG Laser Lithotripsy Efficiency in Percutaneous Nephrolithotomy and Cystolithopaxy?: an In Vitro Study

to test the effect of stone entrapment on laser lithotripsy efficiency. Spherical stone phantoms were created using the BegoStone® plaster. Lithotripsy of one stone (1.0 g) per test jar was performed with Ho:YAG laser (365 µm fiber; 1 minute/trial). Four laser settings were tested: I-0.8 J,8 Hz; II-0.2J,50 Hz; III-0.5 J,50 Hz; IV-1.5 J,40 Hz. Uro-Net (US Endoscopy) deployment was used in 3/9 trials. Post-treatment, stone fragments were strained though a 1mm sieve; after a 7-day drying period fragments and unfragmented stone were weighed. Uro-Net nylon mesh and wire frame resistance were tested (laser fired for 30s). All nets used were evaluated for functionality and strength (compared to 10 new nets). Student's T test was used to compare the studied parameters; significance was set at p < 0.05. Laser settings I and II caused less damage to the net overall; the mesh and wire frame had worst injuries with setting IV; setting III had an intermediate outcome; 42% of nets were rendered unusable and excluded from strength analysis. There was no difference in mean strength between used functional nets and non-used devices (8.05 vs. 7.45 lbs, respectively; p = 0.14). Setting IV was the most efficient for lithotripsy (1.9 ± 0.6 mg/s; p < 0.001) with or without net stabilization; setting III was superior to I and II only if a net was not used. Laser lithotripsy is not optimized by stone entrapment with a net retrieval device which may be damaged by high energy laser settings.

Demography of zooplankton (&lt;i&gt;Anuraeopsis fissa, Brachionus rubens and Moina macrocopa&lt;/i&gt;) fed Chlorella vulgaris and Scenedesmus acutus cultured on different media

Generally zooplankton growth is often limited by the quality of their algal diet. A cheaper common practice in aquaculture, is to culture algae with fertilizers; however, the demography of zooplankton when fed these algae has not yet been evaluated. We studied the population growth and life table demography of the rotifers Anuraeopsis fissa and Brachionus rubens, and the cladoceran Moina macrocopa. For this, the algae Scenedesmus acutus or Chlorella vulgaris were cultured on defined (Bold's basal) medium or the commercial liquid fertilizer (Bayfolan). Experiments were conducted at one algal concentration 1.0 x 10(6) cells/mL of C. vulgaris or its equivalent dry weight of 0.5 x 10(6) cells/mL of S. acutus. The population dynamics were tested at 23 +/- 1 degrees C in 100 mL transparent jars, each with 50mL of the test medium, with an initial density of 0.5indiv/mL, for a total of 48 test jars (3 zooplankton 2 algal species x 2 culture media x 4 replicates). For the life table experiments with M. macrocopa, we introduced 10 neonates (<24h old) into each test jar containing the specific algal type and concentration. For the rotifer experiments, we set 5mL tubes with one neonate each and 10 replicates for each algal species and culture medium. We found that the average rotifer life span was not influenced by the diet, but for M. macrocopa fed S. acutus cultured in Bold's medium, the average lifespan was significantly lower than with the other diets. The gross and net reproductive rates of A. fissa (ranging from 18-36 offspring per female) were significantly higher for C vulgaris cultured in Bold medium. Regardless of the culture medium, Chlorella resulted in significantly higher gross and net reproductive rates for B. rubens than S. acutus diets. The reproductive rates of M. macrocopa were significantly higher in all the tested diets except when fed with S. acutus in Bold medium. The population increase rate, derived from growth experiments of A. fissa and B. rubens, ranged from 0.1-0.25/d and were significantly higher on C vulgaris cultured in liquid fertilizer as compared to the other diets. The growth rates of M. macrocopa ranged from 0.1 to 0.38/d, and were highest with diets of C. vulgaris cultured in Bold medium and S. acutus cultured in fertilizer. Thus, regardless of the culture medium used, the growth rates of the evaluated zooplankton species were higher with Chlorella than with Scenedesmus. The peak population density was highest (2 800ind/mL) for A. fissa fed Chlorella that was cultured on liquid fertilizers, while B. rubens and M. macrocopa had peak abundances of 480 and 12ind/mL, respectively under similar conditions.

Preferences of Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattodea: Rhinotermitidae) among Three Commercial Wood Species.

The Formosan subterranean termite, Coptotermes formosanus Shiraki, and the Asian subterranean termite, Coptotermes gestroi (Wasmann), are both pests of wood in service in Hawaii and Florida. We conducted a laboratory study using method modified from those described in standard E1-09 of the American Wood Protection Association (AWPA 2009) to assess the termite resistance of three commercially available wood species used in regions of the USA where both termite species occur: Douglas fir, Pseudotsuga menziessii, southern yellow pine, Pinus spp. and redwood, Sequoia sempervirens. A multiple-choice (three-choice) assay was used for four weeks (28 days) in order to simulate field conditions of food choice and assess termite feeding preferences under 28 °C and 72–80% RH. 400 termites (360 workers: 40 soldiers) were released into each test jar. Five replicates and two controls of each wood species were used with each termite species. Termite mortality was recorded at the end of the test; and wood wafers were oven-dried and weighed before and after termite exposure to determine the mass loss due to termite feeding, and rated visually on a 0 (failure) to 10 (sound) scale. There were significant differences in mean mass loss values among the three wood species and between two termite species. The mean mass loss value for redwood was significantly lower than Douglas fir and southern yellow pine with both termite species. However, C. formosanus showed increased feeding on Douglas fir and southern yellow pine compared to C. gestroi.

Assessment on the use of biodiesel in cold weather: Pour point determination using a piezoelectric quartz crystal

In order to use biodiesel safely, as an alternative fuel for diesel engines, without fear of cold weather, the pour point of the blends needs to be estimated. This paper is aimed to propose an alternative and easy to use methodology, based on a piezoelectric quartz crystal, to determine the pour point of biodiesels and blended fuels.Impedance and phase of impedance vs. frequency of the piezoelectric quartz crystal change significantly during cooling of biodiesel and biodiesel blended fuels and allows to confirm the role of ethanol as a cold flow improver for biodiesel. Pour point is readily determined by finding the minimum series or parallel frequencies of a barred piezoelectric quartz crystal in contact with the biodiesel blended fuel along cooling. This new methodology only needs the measurement of series frequency, which can be accomplished with high precision by connecting a frequencymeter to a home made oscillator that drives the piezoelectric quartz crystal. Although inexpensive, this new methodology is no more based on visual inspection as the ASTM D97 method, and allows data to be acquired more frequently than the 3°C intervals recommended by the time consuming standard methodology. In the new proposed methodology, data is acquired while the fuel is at the controlled temperature, which is not possible with the ASTM method, where the test jar needs to be removed from the thermostatic bath for visual inspection.Pour points of biodiesel blends with a commercial diesel fuel determined by this new methodology were compared with the ones obtained by the official ASTM methodology. For samples with pour points ranging from 2.3°C (pure biodiesel) to −15.0°C (pure commercial fuel diesel), median pour point values obtained for replicate measurements performed by the two methodologies were not statistically different (α=0.05), although the results obtained by the new methodology were more precise.

Evaluation of primary and secondary production using wastewater as a culture medium

The ability of rotifers and cladocerans to convert primary to secondary production in wastewaters was tested. Scenedesmus acutus was cultured on Bold's (defined) medium, wastewater from the tertiary phase of water treatment and a mixture of both. The algal growth rates (µ) ranged from 0.4 to 0.7 day⁻¹, being highest in defined medium. The demographic characteristics of Brachionus rubens and Moina macrocopa were tested using algae at a density of 1.0 x 10⁶ cells mL⁻¹. Into each test jar, we introduced 20 neonates (< 12-h-old) of either B. rubens or M. macrocopa. Daily (for M. macrocopa) or twice a day (for B. rubens), dead adults and the neonates were enumerated and removed. Average life-span and generation time of B. rubens were not significantly influenced by the algal treatment type. Gross and net reproductive rates were significantly influenced by the medium on which the algae was cultured; in the case of B. rubens, they ranged from 20-36 and 10-22 offspring female⁻¹; the corresponding values for M. macrocopa were higher (38-110 and 13-31 offspring female⁻¹, respectively). The rate of population increase was higher for Brachionus (0.41-0.65 day⁻¹)) compared to Moina (0.28-0.57 day⁻¹). Brachionus had significantly higher growth rates on algae cultured on Bold medium than on treated wastewater while Moina grew significantly better on Scenedesmus cultured on Bold medium or a mixture of treated wastewater and Bold medium than on treated wastewater alone.

Functional responses during the early larval stages of the charal fish Chirostoma riojai (Pisces: Atherinidae) fed rotifers and cladocerans

Survival during early fish larval stages depends largely upon the availability of appropriate prey. Studied were the functional responses from hatching to 6 weeks of age of whitefish (Charal) (Chirostoma riojai) larvae that were offered selected rotifers (Brachionus rotundiformis and B. rubens) and cladocerans (Moina macrocopa and Ceriodaphnia dubia). The experiments were conducted in a 50 ml medium at a salinity of 2 g L−1. Each treatment used four replicates. Rotifers were introduced at densities of 0.5, 1, 2, 4, 8 and 16 individuals ml−1 and cladocerans at 0.1, 0.2, 0.4, 0.8, 1.6, 3.2, 4.8 and 6.4 individuals ml−1. Two larvae, previously starved for 2 h, were introduced into each test jar and allowed to feed for 45 min. The difference between the initial and final zooplankton density represented prey consumption. C. riojai larvae showed Type II functional response curves, i.e. they consumed more zooplankton with increasing prey availability; above a certain prey density (8–16 individuals ml−1 in rotifers and 3.2–6.4 individuals ml−1 in cladocerans) the consumption rate tended to stabilize in most trials. Results are discussed in relation to aquaculture.

Milking characteristics of dairy goats

The objectives of this study were to define and to describe sources of variation and relationships among milking traits of goats. Two data sets collected at the INRA Experimental Station of Bourges (France) were studied: 51 milkings of 30 goats were measured using an experimental automated milk jar which records the volume of milk at each second (data set 1), and 1596 milkings of 133 goats were measured routinely using an automated milk recording system (12 milk jars working simultaneously), recording milk volume every 15 s (data set 2). The analysis of data set 1 indicated that traits associated with milk flow were closely correlated. In particular, the milk collected during the first minute of milking (MF1), traditionally used for characterizing milking ability, was highly correlated with the maximum milk flow (MAMF), the average flow during milking (AMF) and during milk emission (AMFE) (0.92, 0.85 and 0.85, respectively), these last two traits representing the entire milking (milking time and milk emission). MF1 includes a `latency interval or reaction interval' between the setting-up of teat cups and the beginning of milk emission. By using the experimental automated milk jar, three candidate traits were measured and the `latency interval' was estimated: the time at the arrival of milk at the milk claw (TMC), at the test jar (TTJ) and at the recording of the first quantity of milk in the test jar (TR1). These traits were highly correlated with each other, and partially correlated with those traits associated with milk flow and milking time (total milking time (TMT) and milking emission time (MET)). TR1, easily and routinely measured via automated milk recording, can be used to classify animals according to their `latency interval'. Concerning the data set 2, the correlations between the total milking time (TMT) and the other milking characteristics were low due to overmilking which may have occurred in routine milkings. MF1 was highly correlated with MAMF (0.80) while TR1 was negatively correlated with MF1 and MAMF (−0.79 and −0.58, respectively). The age of female, the lactation stage, the milking time and the random effect of female within year of production had a highly significant effect on all characteristics of milking, while litter size had no significant effect. Within lactation, repeatabilities of milking traits were high, in particular for MF1 and TR1.

Fos Induced by Mating or Noncontact Sociosexual Interaction Is Colocalized with Androgen Receptors in Neurons within the Forebrain, Midbrain, and Lumbosacral Spinal Cord of Male Rats

This study was designed to determine the extent to which Fos immunoreactivity (induced either by mating or noncontact sociosexual interaction) and androgen receptor (AR) immunoreactivity are colocalized in brain and spinal cord of male rats. Some males (Mated) were allowed to mate to ejaculation; others (Social Controls) were placed with females but physical contact was prevented by a wire mesh screen; remaining males (Isolated) were placed alone in the test jar for the duration of the test period. After testing, brains and spinal cords were examined for AR and Fos immunoreactivity (ir). PG21 anti-AR and anti-c-fosprimary antibodies were visualized by fluorescence microscopy using cyanine-conjugated and fluorescein-conjugated secondary antibodies. In both brain and spinal cord, the number of Fos-ir neurons varied according to group: Mated males > Social Controls > Isolated males. Fos was highly localized in subsets of AR-ir neurons within the medial preoptic nucleus, bed nucleus of the stria terminalis, dorsomedial nucleus of the amygdala, and central tegmental field. Fos was also localized in subsets of AR-ir neurons within the L5, L6, and S1 segments of the spinal cord. Spinal cord concentrations of AR-ir and Fos-ir neurons were greatest in Lamina X, and the vast majority of Fos-ir neurons in the dorsal part of Lamina X were also AR-ir. Thus, in both brain and spinal cord, androgen-sensitive neurons are active during mating, and transmission of sexually relevant information from cord to brain is probably accomplished via hormone-sensitive spinal neurons.

Radiation in the British Uplands

This paper studied the tolerance of Arundo donax grown in a simulated heavy metals polluted wetland, and determined the biological characters and chlorophyll contents of the plant at its different growth stages as well as the changes of soil heavy metals contents. The results showed that Arundo donax could survive in the wetland when the concentrations of Cu2+, Pb2+, Cd2+, Zn2+, Ni2+ and Hg2+ were 100 mg x kg(-1) and Cr6+ concentration was 50 mg x kg(-1). During 40 days growth period, the chlorophyll content decreased by 20%-56% and the leaf became soft with its tip withered, but the plant still grew. Compared with control, Arundo donax in the polluted wetland was slight and yellow-green, but the impact on plant height was inconspicuous. Arundo donax treated with 100 mg x kg(-1) Cr6+ grew slowly with its root stock rotted, and its leaves withered in a short time, indicating that the plant could not tolerate the pollution of high concentration Cr6+. The concentrations of soil heavy metals declined with the growth of the plant, probably due to the translocation of heavy metals from peripheral soil to rhizosphere and the phytoextraction and phytovolatilization, because the heavy metals contents in rhizosphere were much higher than those in the bulk soil in the test jar. The characters of large biomass, exuberant root and good adaptability of Arundo donax suggested its great potential in remediation of polluted soils. The study on the application of Arundo donax to phytoremediation is of realistic significance.

Factors Affecting Residue-Film Bioassay of Insecticide Residues

Abstract Many factors could affect the mortality of insects and bioassay results: preparation of extracts; method of preparing deposits; loss of volatile insecticides; effect of extractives and additives; age, stage, sex, weight, and species of insects; method of handling insects; size and position of test jars; food used during the test; effect of temperature, humidity, and light; exposure time; contamination of samples; interpretat i on of results; and method of calculating sensitivity. Almost all of these factors affect the mortality of insects, but only a few of them significantly interfere with the final bioassay results if a comparable series of standards is carried on side by side. To obtain more accurate results, all test jars, including the standards, should contain equal amounts of the same extractives; a corresponding standard curve should be prepared from an uncontaminated check for each series of tests; and insects used for each series of tests should be properly sampled from a mixture of several cultures. Within certain limits, the sensitivity of a bioassay may be easily increased by the manipulation of some factors, such as the volume of extract per test jar, age of test insects, size of test container, exposure time, and temperature.

Laboratory studies on the reactions of Simulium larvae to insecticides. I. A laboratory method for studying the effects of insecticide on Simulium larvae.

SummaryA new technique is described for studying the reactions of Simulium larvae to insecticides in the laboratory. By means of a constant stream of air bubbles directed against the inner walls of a large glass test jar, submerged larvae are induced to leave the vegetation on which they were fixed and to become attached to the inner wall of the jar at the point of maximum turbulence. In this position they can be counted and observed throughout the experiment.The larvae receive no handling at all, and mortality in untreated controls remains low for at least 48 hours after larvae have been collected from the field. The water in the experimental jars is replaced with fresh stream water 2 or 3 times during the course of each experiment, and there is no need for a constant supply of untreated and unfiltered running water.The technique has been worked out with particular reference to Simulium damnosum, which react well to these experimental conditions.