氨氮对我国不同产地卤虫的急性毒性试验

采用静水生物试验法测定了ＮＨ３－Ｎ对我国新疆艾比湖（ＡＢ），青海柯柯湖（ＫＫ），海南莺歌海（ＹＧＨ），山东埕口（ＣＫ）产地卤虫的初孵无节幼虫，拟成虫及成体的急性毒性试验。结果表明：１．不同发育阶段的卤虫对氨氮的耐受力是：成虫＞初孵无节幼虫＞拟成虫＞。２．不同产地卤虫对氨氮的耐受力有一定的差异，ＡＢ、ＫＫ、ＣＫ产地的卤虫对氨氮的耐受力均高于ＹＧＨ产卤虫。     

Reduction of Ammonia,Hydrogen Sulfide,and Short‐Chain Fatty Acids Emission during the Sewage Sludge Composting

The effect of mature compost (MC) used as a bulking agent on ammonia, hydrogen sulfide, and short‐chain fatty acids emission reduction during sewage sludge (SS) composting process was studied in this paper. Three types of mixtures, single SS, SS + wood chips (SS + WC), and SS + MC, were composted in a laboratory reactor. Among the different treatments, decrement rates of NH₃ emission (based on initial TN) from SS to SS + MC and SS + WC to SS + MC were 63 and 59%, respectively. The H₂S concentration ranged from 0.759 to 1.140 mg m^?3 for SS, from 0.075 to 0.455 mg m^?3 for SS + WC, and from 0.075 to 0.425 mg m^?3 for SS + MC and the short‐chain fatty acids (C₂–C₅) concentration ranged from 0.10 to 1.00 ppm for SS, from 0.10 to 1.50 ppm for SS + WC, and from 0.10 to 0.80 ppm for SS + MC. In addition, the temperature apparently, as well as the thermophilic stage, was also elevated by bulking agent addition, especially by the MC addition. The denaturing gradient gel electrophoresis analysis indicated that there was more diversity of the bacterial community during the SS + MC process. According to these results, MC was a suitable bulking agent for reduction ammonia, hydrogen sulfide, and short‐chain fatty acids emission during the SS composting.     

A molybdenum oxide annular denuder system for gas phase ambient ammonia measurements

An automated molybdenum oxide annular denuder system (MOADS) has been developed for gas phase ambient ammonia measurements. This system combines high sensitivity (detection limit <50 pptv) with continuous sampling, moderate collection times (30 min) and automated operation. The present denuder design confers two important advantages over the tungsten oxide coated quartz denuder tubes used previously for nitric acid and ammonia measurements. First, the present denuders use oxidized metal substrates and are easier to fabricate and more durable than denuders made from metal oxide coated glass or quartz tubes. Second, molybdenum (VI) oxide surfaces are used which oxidize a reproducible fraction of the adsorbed NH₃ directly to NO upon desorption eliminating the need for a secondary catalytic converter. Laboratory tests of the collection/recovery characteristics of annular denuders made from both the (IV) and (VI) oxides of tungsten and molybdenum are described and preliminary results from field tests are presented.     

The effect of Si and Al concentrations on the removal of U(VI) in the alkaline conditions created by NH3 gas

Remediation of uranium in the deep unsaturated zone is a challenging task, especially in the presence of oxygenated, high-carbonate alkalinity soil and pore water composition typical for arid and semi-arid environments of the western regions of the U.S. This study evaluates the effect of various pore water constituencies on changes of uranium concentrations in alkaline conditions, created in the presence of reactive gases such as NH₃ to effectively mitigate uranium contamination in the vadose zone sediments. This contaminant is a potential source for groundwater pollution through slow infiltration of soluble and highly mobile uranium species towards the water table. The objective of this research was to evaluate uranium sequestration efficiencies in the alkaline synthetic pore water solutions prepared in a broad range of Si, Al, and bicarbonate concentrations typically present in field systems of the western U.S. regions and identify solid uranium-bearing phases that result from ammonia gas treatment. In previous studies (Szecsody et al. 2012; Zhong et al. 2015), although uranium mobility was greatly decreased, solid phases could not be identified at the low uranium concentrations in field-contaminated sediments. The chemical composition of the synthetic pore water used in the experiments varied for silica (5–250 mM), Al³⁺ (2.8 or 5 mM), HCO₃⁻ (0–100 mM) and U(VI) (0.0021–0.0084 mM) in the solution mixture. Experiment results suggested that solutions with Si concentrations higher than 50 mM exhibited greater removal efficiencies of U(VI). Solutions with higher concentrations of bicarbonate also exhibited greater removal efficiencies for Si, Al, and U(VI). Overall, the silica polymerization reaction leading to the formation of Si gel correlated with the removal of U(VI), Si, and Al from the solution. If no Si polymerization was observed, there was no U removal from the supernatant solution. Speciation modeling indicated that the dominant uranium species in the presence of bicarbonate were anionic uranyl carbonate complexes (UO₂(CO₃)₂⁻² and UO₂(CO₃)₃⁻⁴) and in the absence of bicarbonate in the solution, U(VI) major species appeared as uranyl-hydroxide (UO₂(OH)₃⁻ and UO₂(OH)₄⁻²) species. The model also predicted the formation of uranium solid phases. Uranyl carbonates as rutherfordine [UO₂CO₃], cejkaite [Na₄(UO2)(CO₃)₃] and hydrated uranyl silicate phases as Na-boltwoodite [Na(UO₂)(SiO₄)·1.5H₂O] were anticipated for most of the synthetic pore water compositions amended from medium (2.9 mM) to high (100 mM) bicarbonate concentrations.     

The Great Dun Fell Experiment 1995: an overview

During March and April of 1995 a major international field project was conducted at the UMIST field station site on Great Dun Fell in Cumbria, Northern England. The hill cap cloud which frequently envelopes this site was used as a natural flow through reactor to examine the sensitivity of the cloud microphysics to the aerosol entering the cloud and also to investigate the effects of the cloud in changing the aerosol size distribution, chemical composition and associated optical properties. To investigate these processes, detailed measurements of the cloud water chemistry (including the chemistry of sulphur compounds, organic and inorganic oxidised nitrogen and ammonia), cloud microphysics and properties of the aerosol and trace gas concentrations upwind and downwind of the cap cloud were undertaken. It was found that the cloud droplet number was generally strongly correlated to aerosol number concentration, with up to 2000 activated droplets cm⁻³ being observed in the most polluted conditions. In such conditions it was inferred that hygroscopic organic compounds were important in the activation process. Often, the size distribution of the aerosol was substantially modified by the cloud processing, largely due to the aqueous phase oxidation of S(IV) to sulphate by hydrogen peroxide, but also through the uptake and fixing of gas phase nitric acid as nitrate, increasing the calculated optical scattering of the aerosol substantially (by up to 24%). New particle formation was also observed in the ultrafine aerosol mode (at about 5 nm) downwind of the cap cloud, particularly in conditions of low total aerosol surface area and in the presence of ammonia and HCl gases. This was seen to occur at night as well as during the day via a mechanism which is not yet understood. The implications of these results for parameterising aerosol growth in Global Climate Models are explored.     

新疆砂岩型氧化铜矿溶剂萃取工艺研究

溶剂萃取技术是目前常用的处理低浓度铜溶液的方法。根据新疆砂岩型铜矿资源和自然条件等特点，对不同浸出工艺条件、不同浸出溶液进行了溶剂萃取的工艺基础研究，提出了基于低浓度氨堆浸出－萃取－电积工艺，以达到成功开发新疆砂岩型氧化铜矿之目的。     

Benthic primary production, respiration and remineralisation: in situ measurements in the soft-bottom Abra alba community of the western English Channel (North Brittany)

In situ measurements of ammonium and carbon dioxide fluxes were performed using benthic chambers at the end of spring and the end of summer in two soft-bottom Abra alba communities of the western English Channel (North Brittany): the muddy sand community (5 m, about 10% of surface irradiance) and the fine-sand community (19 m, about 1% of surface irradiance). High rates of ammonium regeneration were measured in the two communities at the end of summer (296.03±40.07 and 201.7±62.74 μmolN m⁻² h⁻¹, respectively) as well as high respiration rates (2.60±0.94 and 2.23±0.59 mmolC m⁻² h⁻¹, respectively). Significant benthic gross primary production (up to 6.11 mmolC m⁻² h⁻¹) was measured in the muddy sand community but no benthic primary production was measured in the fine-sand community. It suggests that microphytobenthic production values used in simulations previously published for these two communities were overestimated while values of community respiration were underestimated. The study confirms that this benthic system is heterotrophic and strengthens the idea that an important pelagic-benthic coupling is required for the functioning in such coastal ecosystems.     

氨及亚硝酸盐对真鲷仔鱼的急性毒性研究

氨是水产动物蛋白质代谢的最终产物,亚硝酸盐是氨硝化作用的中间产物。在养殖系统中氨及亚硝酸盐都有可能积累到使鱼放毒的程度。因而了解养殖对象对氨及亚硝酸盐的忍耐程度是必需的。