Evaluation of nitrifying activity in sediments by dark C-bicarbonate incorporation

A method has been developed for measuring the activity of nitrifying bacteria in sediment samples within very short incubation times (a few hours). Biological dark ¹⁴C-bicarbonate incorporation is measured with and without addition of 5 mg 1⁻¹ N-serve, a substance which was proved to be a specific inhibitor of autotrophic CO₂-fixation by nitrifying bacteria. The value of N-serve sensitive bicarbonate incorporation can be quantitatively related to the rate of nitrogen oxidation by autotrophic nitrifiers.First application of this method on marine sediments gives results in good agreement with information provided by other methods. Nitrification rates in the range 0–20 μmole nitrogen oxidized per dm³ sediment and per hour are found in the upper cm of the sediments of the coastal regions of the Southern Bight of the North Sea.     

Spatial distribution of radionuclides in soil around a coal-fired power plant: 210Pb, 210Po, 226Ra, 232Th, 40K emitted with the fly ash and 137Cs from the worldwide weapon testing fallout

To determine the effect of airborne emissions of radionuclides from coal-fired power plants on the environment, the concentrations of the most important radionuclides were measured in soil samples from the local environments (0.4–5.2 km) as well as in fly ash. The spatial distribution of the radionuclides in the soil did not indicate any significantly increased concentrations in the area downwind of the plant compared to other areas; the ratios ²¹⁰Pb/²²⁶Ra and ²¹⁰Po/²²⁶Ra were within the range observed for unaffected soils. The emissions from the plant, though present, are obviously too small to significantly change the natural local distribution pattern of the radionuclides in the soil. A highly significant correlation between ⁴⁰K and ²³²Th was observed which was independent of the different types of soils found in this area. The concentration of ¹³⁷Cs in topsoil, which is the result of worldwide fallout from nuclear weapons testing, varied at some places even within a small distance (～ 2 km) by up to one order of magnitude. Furthermore, it was observed that the concentration of ¹³⁷Cs in soils from cropland was on average a factor of 2 less than in those from grassland. This variability has to be considered in planning monitoring programs around nuclear power plants, which may also release this radionuclide.     

The effects of nickel and cadmium on the growth rate of Hydra littoralis and an assessment of the rate of uptake of 63Ni and 14C by the same organism

Hydra littoralis was used as a bioassay organism to determine the sublethal threshold concentrations of NiCl₂ and CdCl₂: the concentrations were found to be 75 and 20 μg 1^?1 respectively.The rates of uptake of ¹⁴C and ⁶³Ni were measured over periods of 24 h. It seemed that Hydra reached an equilibrium with ¹⁴C within this period, whereas the total uptake of ⁶³Ni was proportional to time.The changes in the mean specific growth rate of Hydra when related to the uptake of ⁶³Ni showed it probable that a detoxication process is taking place within the organism.     

Measurement of the adsorption of 14C-Polyethyleneimine polymers during flocculation of silica,bacteria and algae

¹⁴C-Polyethyleneimine polymers of two different mol. wts have been prepared. These polymers have been used to study the flocculation of silica in water, of the bacterium E. coli in its nutrient and over a range of polymer concentration from about 1 to 1000 ppm. The degree of flocculation, and the amounts of polymer adsorbed on the colloid surface and the corresponding equilibrium concentration of polymer in solution have been measured. The concentration of polymer added to produce flocculation increased in the ratio from 1:30:500 in comparing silica. E. coli and C. ellipsoidia, respectively. However, the amount of polymer adsorbed on the same three colloids labelled with the tagged polymer, increased in the ratio 1:10:20 under comparable conditions. The higher concentrations needed to flocculate the two biocolloids cannot, therefore, be attributed to lack of adsorbed polymer on the surface. It is also true that much higher concentrations of polymer were needed on the surface to reverse the charge on the biocolloids compared with silica in order that flocculation might occur. The results are discussed briefly especially in relation to the need to explain flocculation phenomena in terms of the surface areas of the colloids and surface coverage by the polymers. Experimental results are reported which indicate that interaction of PEI polymers with anions in the algal and E. coli nutrients, and with biopolymers formed in the growth of the latter are important in affecting flocculation.     

Specific activity of nitrifying biofilm in water nitrification process

The effect of the accumulation of fixed biomass on the specific activity of nitrifying biofilm was studied in a continuous flow reactor. The specific activity of nitrifying biofilm was described by the specific removal rate of ammonium-N (q_obs). The observed relationship between q_obs and the film thickness was apparent to an inverse V-shaped curve. The maximum specific activity of biofilm was attained at a film thickness in the range 15–25 μm, at which a steady state was established in the liquid phase for different influent ammonium-N concentrations (S₀). Beyond such a range, the specific activity began to decline significantly with the additional accumulation of biofilm. It was demonstrated from both experimental and theoretical approaches that reduction in the specific activity of biofilm was closely related to the ratio of active biomass to the accumulation of inactive materials within the biofilm.     

10万立方米干式煤气柜的大修与调试

总结了10万m∧3干式柜的大修调试工作,提出了柜体倾斜、导轨、导轮运行不正常、漏油等问题的处理方法。     

新疆阿克塔斯金矿含金石英脉40Ar/39Ar年代学及其地质意义

新疆富蕴县阿克塔斯金矿位于额尔齐斯断裂带的东南部。文章通过对含金石英脉的40Ar/39Ar同位素测年获得等时线年龄为(240.38±4.89)Ma,反等时限线年龄为(240.51±4.80)Ma,限定金矿的成矿时间为240Ma±,属于早三叠世。区域资料表明,额尔齐斯断裂带经历270~310Ma和240~260Ma两幕剪切变形,阿克塔斯金矿成矿受韧—脆性剪切作用控制,对应260~240Ma剪切变形事件。     

Seasonal variation of denitrification rate in sediment determined by use of 15N

A laboratory method of determination of sediment denitrification capability is described. The determination of nitrogen gas evolved from ¹⁵N-labelled nitrate is based on the principle of isotope dilution. The gas evolved is spiked with unlabelled dinitrogen and the ¹⁵N-enrichment of the resulting gas mixture is measured by optical spectrometry.The amount of nitrate reduced to ammonia and organic nitrogen is determined simultaneously. Measurements performed on sediment from a shallow Danish lake indicated first order kinetics of denitrification with respect to nitrate concentration. Great seasonal variation of rate constant was found with maximum value in late August. This variation is probably governed by the pattern of accumulation of decomposable organic matter in sediment.Calculation based on measured rate constants and nitrate concentrations during the year indicate that approximately 10% of the total nitrogen loading of the lake is denitrified.     

Transport of 14C-labelled PCB compounds from sediment to water and from water to air in laboratory model systems

Tetra-, hexa- and octachlorobiphenyls were added to aquatic model systems composed of undisturbed sediment cores with an overlying water phase. Using impactor plates transport of the compounds from sediment to air was observed. About one per cent of the sediment-bound PCBs recovered in the systems left the water by jet drops from bursting bubbles. The transport of PCBs from the sediment to the air was nearly constant over time, with a transport rate of 0.62 μg · dm^?2 week^?1 for tetrachlorobiphenyl. Tetrachlorobiphenyl was mobile in systems with and without macroinvertebrates and in those fixed with HgCl₂. Hexa- and octachlorobiphenyls were transported from sediment to water mainly by bioturbation processes. The two latter substances had a higher adsorption to particles than tetrachlorobiphenyl. Compared to tetrachlorobiphenyl, more hexa- and octachlorobiphenyls accumulated in chironomids and tubificids.     

Performance and biofilm activity of nitrifying biofilters removing trihalomethanes

Nitrifying biofilters seeded with three different mixed-culture sources removed trichloromethane (TCM) and dibromochloromethane (DBCM) with removals reaching 18% for TCM and 75% for DBCM. In addition, resuspended biofilm removed TCM, bromodichloromethane (BDCM), DBCM, and tribromomethane (TBM) in backwash batch kinetic tests, demonstrating that the biofilters contained organisms capable of biotransforming the four regulated trihalomethanes (THMs) commonly found in treated drinking water. Upon the initial and subsequent increased TCM addition, total ammonia nitrogen (TOTNH₃) removal decreased and then reestablished, indicating an adjustment by the biofilm bacteria. In addition, changes in DBCM removal indicated a change in activity related to DBCM. The backwash batch kinetic tests provided a useful tool to evaluate the biofilm’s bacteria. Based on these experiments, the biofilters contained bacteria with similar THM removal kinetics to those seen in previous batch kinetic experiments. Overall, performance or selection does not seem based specifically on nutrients, source water, or source cultures and most likely results from THM product toxicity, and the use of GAC media appeared to offer benefits over anthracite for biofilter stability and long-term performance, although the reasons for this advantage are not apparent based on research to date.     

Effects of bacterial activity on estrogen removal in nitrifying activated sludge

The effects of bacterial activity on the degradation of estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2) in nitrifying activated sludge (NAS) were studied with different substrates and organic loading rates (OLRs) and low temperature conditions. Heterotroph was shown to have utilized glucose prior to E1 for metabolism. The co-metabolism of ammonia oxidizing bacteria (AOB) dominated the degradation of E1, E2 and EE2 in NAS. The higher the organic loading, the higher the rate of organic matter transformation, with less ammonia oxidation and less degradation of E1, E2 and EE2. The degradation of E3 in NAS was shown to be largely due to heterotroph metabolism. On the basis of the difference of apparent activity between heterotroph and AOB at 4 degrees C, the process of estrogen degradation via the co-metabolism of AOB was able to be identified.     

Pb and 210Pb in a tropical river environment

The Periyar River in south India receives the major share of Pb and ²¹⁰Pb from effluents released by factories along its bank that process monazite ore and rock phosphate. Their distribution in the river system is influenced by the rains during the monsoon and by salinity during the non-monsoon period. The concentration of both Pb and ²¹⁰Pb in the sediments from the backwater zone was observed to increase during the monsoon due to sediment transport from the upstream industrial zone. The water in the backwater zone showed increased levels of Pb and ²¹⁰Pb in the non-monsoon period, due possibly to solubilization from the sediments as a result of salinity changes. The levels of Pb and ²¹⁰Pb in the river water are much lower than the international standards for safe limits in drinking water. No significant concentration of Pb and ²¹⁰Pb above a background level was observed in fish obtained from the river.     

改良型A^2O工艺的除磷脱氮运行效果

结合常州市城北污水厂的实际,介绍了改良型A^2O工艺除磷脱氮的处理效果。实践表明,改良型A^2O工艺与传统工艺相比,除TN去除率略有下降处,对有机物、NH3－N及TP的去除率均有较明显的上升,对TP的去除效果更优,同时运行成本得到降低。     

Metabolic activity in cores of lake-bottom sediments

The catabolic activity of various levels of lake-bottom sediment cores (from 0 to 10 at 2.5-cm intervals) was measured by the production of ¹⁴CO₂ from radioactively-labelled substrate at in situ temperatures. All levels of sediment were found to possess activity, which decreased with core depth, except the 7.5- and 10.0-cm levels of the March core. This lack of activity was shown to be due to the relatively low in situ temperature for the March core. An anabolic activity profile indicated that a considerable degree of anabolism occurred at various core levels. It was also found that the non-biological binding that occurred at the different core levels decreased with core depth, which may be related to the measured decrease in particulate matter with core depth. The addition of soluble nitrogen to the July sediment core resulted in an increased nitrogen concentration in the sediment and a concomitant increase in catabolic activity.     

137Caesium content of Umbilicaria species,with particular reference to altitude

The lichens Umbilicaria cylindrica and U. deusta are good bioindicators of ¹³⁷Cs; U. hirsuta and U. murina are apparently less effective in this role. Specific radioactivity and ¹³⁷Cs content in lichen thalli from numerous localities in southwest Poland, growing at altitudes from 400 to 1200 m, were investigated. The data assembled are interpreted graphically and formulae derived to show the influence of altitude on the ¹³⁷Cs content; in general, the coefficient of accumulation rises with increasing altitude.     

Recent sedimentation rates and 210Pb fluxes in Georgian Bay and Lake Huron

The ²¹⁰Pb and ¹³⁷Cs profiles are determined at five locations in Georgian Bay and Lake Huron. Compaction-corrected recent sedimentation rates are derived for all locations using the ²¹⁰Pb data. The rates range from 0.13 ± 0.03 mm y^?1 (2.2 ± 0.4 mg cm^?2 y^?1) to 0.78 ± 0.06 mm y^?1 (14.5 ± 1.1 mg cm^?2 y^?1). Except for one location, the rates show marginal to good agreement with those estimated from palynological measurements at four of the five study locations. ¹³⁷Cs profiles at study locations suggest that the top portions of the sediment cores were satisfactorily retrieved during coring and sectioning operations. However, considerable downward migration of ¹³Cs is noted at three locations. The fluxes of excess ²¹⁰Pb vary between 0.06 and 0.27 pCi cm^?2 y^?1. The average depositional flux is found to be considerably lower than the flux of atmospheric ²¹⁰Pb. It is postulated that the deposition of atmospheric ²¹⁰Pb in Lake Huron and Georgian Bay sediments is limited by the supply of scavenging particulates.     

A bacterial methylmercury-mineralizing activity in river sediments

A bacterial activity involving mineralization of methylmercury was found in bottom sediments of the river Sambre (Belgium), in a zone highly polluted with inorganic mercury. The possibility, shown by other authors and ourselves, that biological production of toxic methylmercury compounds occurs in such a medium gives a great ecological significance to this finding.Some properties of this mineralizing activity were studied at the community level in the laboratory.The mineralizing capacity of the community can be increased in response to increased concentrations of methylmercury, probably by means of the selection of methylmercury-resistant bacterial species, among which the organisms responsible for the transformation constitute only a part.Because of this adaptation, it is suggested that some equilibrium can be reached between the degradation of methylmercury and its addition to, or its production in, mineral mercury polluted environments.     

Evaluation of UV/H2O2 treatment for the oxidation of pharmaceuticals in wastewater

Advanced oxidation treatment using low pressure UV light coupled with hydrogen peroxide (UV/H₂O₂) was evaluated for the oxidation of six pharmaceuticals in three wastewater effluents. The removal of these six pharmaceuticals (meprobamate, carbamazepine, dilantin, atenolol, primidone and trimethoprim) varied between no observed removal and >90%. The role of the water quality (i.e., alkalinity, nitrite, and specifically effluent organic matter (EfOM)) on hydroxyl radical (OH) exposure was evaluated and used to explain the differences in pharmaceutical removal between the three wastewaters. Results indicated that the efficacy of UV/H₂O₂ treatment for the removal of pharmaceuticals from wastewater was a function of not only the concentration of EfOM but also its inherent reactivity towards OH. The removal of pharmaceuticals also correlated with reductions in ultraviolet absorbance at 254 nm (UV₂₅₄), which offers utilities a surrogate to assess pharmaceutical removal efficiency during UV/H₂O₂ treatment.     

Deposition of 226Ra on surfaces during precipitation and leaching of (Ba,Ra)SO4

Formation of a barium-radium sulphate precipitate occurs during the treatment of uranium tailings decants with barium chloride to remove ²²⁶Ra. This note presents results from experiments designed to identify the importance of radium adsorption onto the (Ba, Ra)SO₄ precipitate as a mechanism for removal. Adsorption was investigated indirectly by forming a precipitate and then measuring radium release during leaching.In the conduct of the precipitation/leaching experiments serious difficulties were encountered initially in obtaining satisfactory mass balances—radium recoveries were quite low. EDTA extractions of apparatus revealed that significant quantities of ²²⁶Ra were adhering to apparatus surfaces during both precipitation and leaching. This has important implications for treatment process design, the behaviour of radium in the environment and for the conduct of experimental work. Although the amounts of radium adhering to surfaces were significant relative to levels in solution, the total release of radium from sludge during distilled water leaching was not large. The results of the leaching tests indicated that during precipitation the radium is incorporated into the precipitate rather than adsorbed on its surface.     

Sedimentation rates in Western Nipigon Bay,Lake Superior using the 210Pb method

²¹⁰Pb, ²²⁶Ra and ¹³⁷Cs profiles have been measured for sediment cores from three locations in western Nipigon Bay, Lake Superior, Canada. Compaction of the sediment with depth of burial was taken into account in calculating recent sedimentation rates and age profiles at these locations from the excess ²¹⁰Pb profiles. The rates at two of the locations were 0.85±0.03 mmy^?1 (16.7 mg cm^?2 y^?1) and 1.39±0.12 mmy^?1 (29.5 mg cm^?2 y^?1). The third core had an anomaly in the ²¹⁰Pb profile below a depth of 3.5 cm corresponding to the time that the outfall of a nearby pulp mill was relocated. The ¹³⁷Cs profiles of the two undisturbed cores were in accord with the corresponding age/depth curves derived from the ²¹⁰Pb measurements.