A new micro-detection tube for cholinesterase inhibitors in water

A cheap and simple but very sensitive and specific detection tube has been developed for the detection of cholinesterase-inhibiting compounds in natural and waste water disinfected with chlorine-containing oxidants. After the oxidants have been quantitatively destroyed by a mixture of NaNO(2) and NaHCO(3), the horse-serum cholinesterase catalyses the hydrolysis of the orange-red 2,6-dichloro-indophenyl acetate producing the blue 2,6-dichloroindophenol. The colour transformation does not occur when the enzyme is inactivated by the cholinesterase-inhibiting compounds. By making use of a chemical heater the detection tube can complete a check job at an environmental temperature as low as about 0 degrees C in only 5 min. The plastic-made detection tube is composed of an inner tube for use in chemical reaction and an outer tube for use in chemical heating. DDVP can be detected at concentrations as low as 2 microg ml(-1), when the sampled water volume is 0.5 ml.     

Spermatogenesis inPyrosoma atlanticum (Tunicata: Thaliacea: Pyrosomatida): Implications for tunicate phylogeny

Colonies ofPyrosoma atlanticum were collected by submersible in October 1988 in the Caribbean Sea, and testes were studied by electron microscopy. Spermatogonia, spermatocytes and early spermatids have two centrioles. The proximal centriole subsequently disappears, its remains apparently persisting in the spermatozoon as dense material adjacent to the distal centriole, which gives rise to the axoneme. At the tip of early spermatids are several 50 nm proacrosomal vesicles, which disappear leaving no trace in early elongating spermatids. The spermatozoon lacks an acrosome and has a head 35µm long. The head is differentiated into a bulbous posterior portion 5µm long × 1µm wide, a thinner anterior portion 25µm long tapering from a width of 0.7µm to a width of 0.4µm, and a very thin anterior extension 5µm long × 0.5µm wide. At the start of elongation, the anterior extension begins to form just lateral to the proacrosomal vesicles as a spiral projection comprising part of the nucleus, covered by a thin sheath of cytoplasm. This sheath of cytoplasm undergoes a complex differentiation. Ultimately, the nucleus in the anterior extension is overlain by two membrane-bound sheaths of cytoplasm connected by a spiral flange of cytoplasm. Between these two sheaths is a spiral space, open to the exterior through a subterminal pore near the sperm tip. In early spermatids the mitochondria fuse into a single mitochondrion, which remains lateral to the nucleus. The cristae become modified late in spermatogenesis. Throughout elongation of the spermatid there are patches of dense material between the nucleus and mitochondrion. A manchette of microtubules transiently encircles the thin anterior portion of the nucleus during the last phase of elongation. A manchette is not present during most of elongation. In the spermatozoon the mitochondrion, which has reticulate cristae, spirals a few times about the nucleus and extends from the junction between the bulbous portion and the thinner anterior portion of the nucleus to the junction between the thinner anterior portion and the nuclear extension. Spermatogenesis inP. atlanticum, compared to that in other tunicates, most closely resembles that in colonial ascidians, and supports the majority view that pyrosomes arose from aplousobranch ascidians that lost their attachment to the substratum. Pyrosome sperm are more highly derived than doliolid sperm, which have an acrosome that is probably capable of exocytosis. When salp and pyrosome sperm are compared, both are highly derived, but neither shares any apomorphies with the other that it does not share with at least one other tunicate order. Thus, sperm morphology does not support the majority view that pyrosomes gave rise to doliolids and neither confirms nor denies the idea that pyrosomes are intermediate between aplousobranch ascidians and salps. Therefore, it is likely that the class Thaliacea is polyphyletic, with doliolids arising very early from the ascidian lineage and with salps and pyrosomes arising somewhat later.     

Field studies on 32P movement and P leaching from flooded paddy soils in the region of Taihu Lake, China

Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2 32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0-5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25-30 cm layer was only about 1-2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0-30 cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5-5.8% and 1.6-2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist.     

Boiler briquette coal versus raw coal: Part I--Stack gas emissions

Stack gas emissions were characterized for a steam-generating boiler commonly used in China. The boiler was tested when fired with a newly formulated boiler briquette coal (BB-coal) and when fired with conventional raw coal (R-coal). The stack gas emissions were analyzed to determine emission rates and emission factors and to develop chemical source profiles. A dilution source sampling system was used to collect PM on both Teflon membrane filters and quartz fiber filters. The Teflon filters were analyzed gravimetrically for PM10 and PM2.5 mass concentrations and by X-ray fluorescence (XRF) for trace elements. The quartz fiber filters were analyzed for organic carbon (OC) and elemental carbon (EC) using a thermal/optical reflectance technique. Sulfur dioxide was measured using the standard wet chemistry method. Carbon monoxide was measured using an Orsat combustion analyzer. The emission rates of the R-coal combustion (in kg/hr), determined using the measured stack gas concentrations and the stack gas emission rates, were 0.74 for PM10, 0.38 for PM2.5, 20.7 for SO2, and 6.8 for CO, while those of the BB-coal combustion were 0.95 for PM10, 0.30 for PM2.5, 7.5 for SO2, and 5.3 for CO. The fuel-mass-based emission factors (in g/kg) of the R-coal, determined using the emission rates and the fuel burn rates, were 1.68 for PM10, 0.87 for PM2.5, 46.7 for SO2, and 15 for CO, while those of the BB-coal were 2.51 for PM10, 0.79 for PM2.5, 19.9 for SO2, and 14 for CO. The task-based emission factors (in g/ton steam generated) of the R-coal, determined using the fuel-mass-based emission factors and the coal/steam conversion factors, were 0.23 for PM10, 0.12 for PM2.5, 6.4 for SO2, and 2.0 for CO, while those of the BB-coal were 0.30 for PM10, 0.094 for PM2.5, 2.4 for SO2, and 1.7 for CO. PM10 and PM2.5 elemental compositions are also presented for both types of coal tested in the study.     

Gas-phase reaction of CCl2F2 (CFC-12) with methane

Gas-phase reaction of CFC-12 (CCl2F2) with methane was carried out in a plug flow reactor over the temperature range of 873-1123 K. The major organic halocarbons formed during the reaction were C2F4, C2H2F2, CHClF2, CH3Cl, C3H2F6 and CCl3F. The formation of all products except C2H2F2 decreased with temperature, while the selectivity to C2H2F2 (difluoroethylene) increased with temperature and reached approximately 80% at 1123 K. Under these reaction conditions, methane acts as hydrogen and carbon source, resulting in the formation of an unsaturated C2 hydrofluorocarbon from two C1 precursors.     

Rainwater chemistry at the summit and southern flank of the Itatiaia massif, Southeastern Brazil

Wet deposition and related rainwater chemistry were studied at the Itatiaia massif, on which is settled the Itatiaia National Park (INP). Samples were simultaneously collected on a weekly basis over 12 months, using automated wet and dry samplers, at the INP-Headquarters (INP-Hq; altitude=820 m) and the Itatiaia Plateau (It-Pt; altitude=2460 m). Conductivity, pH, Na(+), K(+), Mg(2+), Ca(2+), NH(4)(+), Cl(-), NO(3)(-) and SO(4)(2-) were determined in 36 rainwater samples. Volume-weighted mean (VWM) pH was lower at the INP-Hq (4.9) than at the It-Pt (5.3). Very strong correlation between Cl(-) and Na(+) was found for the INP-Hq (r=0.99). At the Itatiaia massif, SO(4)(2-), NO(3)(-), and NH(4)(+) comprised together about 60% of the total inorganic ions and appear to exert the major control on rainwater pH.     

Temporal changes in kerosene content and composition in field soil as a result of leaching

A field experiment was designed to determine the combined effect of leaching and natural attenuation on the redistribution dynamics of kerosene--a volatile petroleum hydrocarbon mixture (VPHM)--and of its selected individual components in the soil subsurface. Variables included the composition of contaminant spilled, the soil water content before contamination and the leaching pattern. Temporal changes in the residual kerosene concentration and composition in the soil subsurface of the experimental field during 39 days and leaching by 500 mm of irrigation water were determined to a depth of 100 cm. The main processes controlling contaminant attenuation were volatilization and redistribution with depth. Soil hydration status was found to affect the attenuation, redistribution and composition of VPHM in the porous media. An initial relative increase of n-alkanes in the subsurface compared with the total VPHM in the first leaching period was a result of the volatilization of low vapor pressure compounds. The redistribution of individual components in the soil profile during leaching was in accordance with their physico-chemical properties.     

The Danish incinerator dioxin study. Part 1

During the last two years an extensive series of dioxin measurements has been conducted on Danish municipal and hospital solid waste incinerators. The study was directed toward finding the total annual dioxin emissions from MSWI in Denmark, now estimated to be 3 kg. of dioxines and furanes. This sum is equivalent to 50 g. of 2,3,7,8-TCDD according to the Nordic Equivalents. Measurements were carried out according to a statistical design following a plan of pre-randomized sampling. This procedure allowed causal interpretation of the correlations found between the dioxin emissions and certain operating parameters. The statistical model obtained describes the emissions by variations between incinerators, by variation in time, and by changes in the load, the excess air and the HCl concentration in the flue gas.     

Mobility of Zn, Cd and Pb in soils as affected by poultry litter extract--I. Leaching in soil columns

Application of poultry litter to cropland may increase metal mobility, because the soluble organic ligands in poultry litter can form water-soluble complexes with metals. In this study, one uncontaminated soil and two metal-contaminated soils were sampled. A portion of the uncontaminated soil was amended with Zn, Pb, and Cd at rates of 400, 200, and 8 mg kg(-1), respectively. Packed soil columns were leached with H2O, EDTA, CaCl2, and poultry litter extract (PLE) solutions separately. No leaching of Zn, Cd, and Pb with the PLE was found in the uncontaminated soil. The retention of PLE-borne Zn indicated the potential for Zn accumulation in the soil. A large portion of the metals was leached from the metal-amended soil, and EDTA solubilized more Zn, Cd, and Pb than CaCl2 and PLE. In the metal-contaminated soils, the leaching of Zn and Cd with PLE was consistently larger than that for CaCl2, indicating that these metals were mobilized by organic ligands. The PLE did not mobilize Pb in these soils. The utilization of poultry litter in metal-contaminated soils might accelerate the movement of Zn and Cd in soil profiles.     

The oldest known tracks of web-footed birds from the Lower Cretaceous of South Korea

 We describe the oldest tracks of web-footed birds from the Early Cretaceous in South Korea. The tracks are characterized by a wide divarication angle and a long reversed hallux. The web is semipalmate and restricted to the proximal portion of the three forward digits. The tracks from the Early Cretaceous in South Korea are smaller than those of the Late Cretaceous, therefore confirming the trend of size increasing in the early evolution of birds as shown by skeletal fossils. The discovery of web-footed tracks with abundant non-web-footed tracks indicates that there was a considerable diversification of shore birds as early as the Early Cretaceous. Received: 4 November 1999 / Accepted in revised form: 28 February 2000