Dynamique des populations de Tisbe holothuriae (Crustacea: Copepoda) en élevage sur trois régimes artificiels différents

The influence of three different artificial diets (Tetramin, Bioter food and Renutryl) on the life cycle of Tisbe holothuriae Humes, 1957 has been investigated under constant experimental conditions (19°C; 38 S). Females (F2) whose life history has been followed, were obtained from a common mother (F1). They were bred in 50 ml dishes and transferred into a fresh container as soon as they produced a new egg-sac. Offspring (F3) resulting from successive egg-layings were counted as soon as they moulted into adults. Larval mortality was estimated in two ways: (1) by enumeration of adults issuing from a known number of nauplii; (2) by comparison of the average number of eggs from egg-sacs of F2 with the average number of adult offspring F3. The life-span of F2 females, including the larval stages, varies between 23.6 days (Renutryl diet) and 33.4 days (Tetramin diet). The first egg-sac appears about 12 days after hatching, whatever diet is used. The first copulation immediately follows the last moult, about 8 days after hatching. The reproductive period lasts for 6.5 (Renutryl) to 10.4 days (Bioter). The average number of successive egg-sacs laid is minimal with Renutryl (3.7) and maximal with Tetramin (5.1), but actual egg production is higher with Renutryl (86 eggs/sac) than with Bioter (67) or Tetramin (58). Nevertheless, as a result of varying larval mortality with the different diets, eventual numbers of adult F3 obtained are significantly higher with Bioter (310) than with Tetramin and Renutryl (216 and 188, respectively). The offspring F3 sex-ratio varies in successive broods and with the nature of the food offered: more females are produced with Bioter or Renutryl than with the Tetramin diet. Then net reproduction rate, R ₀, is higher with Bioter, because of the low larval mortality, high fertility, and high ratio of females resulting from this diet. The intrinsic rate of natural increase (r _m) is similar with Renutryl and Bioter diets (0.298 and 0.301, respectively), a lower value (0.260) occurs with the Tetramin diet. These different values are discussed and compared with previous data for Tisbe species fed natural diets.     

A two-dimensional model for simulating the transport and fate of toxic chemicals in a stratified reservoir

A two-dimensional reservoir toxics model is essential to establishing effective water resources management and protection. In a reservoir, the fate of a toxic chemical is closely connected with flow regimes and circulation patterns. To better understand the kinetic processes and persistence and predict the dissipation of toxic contaminants in the reservoir during a spill or storm runoff event, a toxics submodel was developed and incorporated into an existing laterally integrated hydrodynamics and transport model. The toxics submodel describes the physical, chemical, and biological processes and predicts unsteady vertical and longitudinal distributions of a toxic chemical. The two-dimensional toxicant simulation model was applied to Shasta Reservoir in California to simulate the physico-chemical processes and fate of a volatile toxic compound, methyl isothiocyanate (MITC), during a chemical spill into the Sacramento River in 1991. The predicted MITC concentrations were compared with those observed. The effect of reservoir flow regimes on the transport and fate of the toxic substance was investigated. The results suggested that the persistence of MITC is significantly influenced by different flow regimes. Methyl isothiocyanate is more persistent in the reservoir under an interflow condition due to reduced volatilization from deep layers than under an overflow condition. In the overflow situation, the plume moved more slowly toward the dam and experienced greater dissipation. This analysis can assist in toxic spill control and reservoir management, including field sampling and closure of water intakes.     

壳聚糖-丙烯酰胺-二甲基二烯丙基氯化铵三元接枝共聚物的合成及应用

在N2保护下，以硝硬驱铈铵为引发剂，将壳聚糖（CTS）、丙烯酰胺（AM）及二甲基二烯丙基氯化铵（DMDAAC）接枝共聚得到CTS-AM-DMDAAC三元接枝共聚物，考察了反应条件对接枝共聚反应的影响。实验结果表明，在反应温度50℃、反应时间5-6h，m（CTS）：m（AM）：m（DMAAAC）=1：6：0.67、c（Ce^4＋）=0.8mmol/L的最佳反应条件下，接枝共聚反应的接枝率和接枝效率分别为64%和10.5%。用傅里叶变换红外光谱仪对CTS-AM-DMDAAC进行了表征。絮凝实验结果表明：CTS-AM-DMDAAC对高岭土水样具有较强的絮凝能力，可在很宽的pH范围内使用。用CTS-AM-DMDAAC处理COD为165.5mg/L的啤酒生产废水，COD去除率达90.1%.     

Functionally relevant microorganisms to enhanced biological phosphorus removal performance at full-scale wastewater treatment plants in the United States

The abundance and relevance ofAccumulibacter phosphatis (presumed to be polyphosphate-accumulating organisms [PAOs]), Competibacter phosphatis (presumed to be glycogen-accumulating organisms [GAOs]), and tetrad-forming organisms (TFOs) to phosphorus removal performance at six full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plants were investigated. Coexistence of various levels of candidate PAOs and GAOs were found at these facilities. Accumulibacter were found to be 5 to 20% of the total bacterial population, and Competibacter were 0 to 20% of the total bacteria population. The TFO abundance varied from nondetectable to dominant. Anaerobic phosphorus (P) release to acetate uptake ratios (P(rel)/HAc(up)) obtained from bench tests were correlated positively with the abundance ratio of Accumulibacter/(Competibacter +TFOs) and negatively with the abundance of (Competibacter +TFOs) for all plants except one, suggesting the relevance of these candidate organisms to EBPR processes. However, effluent phosphorus concentration, amount of phosphorus removed, and process stability in an EBPR system were not directly related to high PAO abundance or mutually exclusive with a high GAO fraction. The plant that had the lowest average effluent phosphorus and highest stability rating had the lowest P(rel)/HAc(up) and the most TFOs. Evaluation of full-scale EBPR performance data indicated that low effluent phosphorus concentration and high process stability are positively correlated with the influent readily biodegradable chemical oxygen demand-to-phosphorus ratio. A system-level carbon-distribution-based conceptual model is proposed for capturing the dynamic competition between PAOs and GAOs and their effect on an EBPR process, and the results from this study seem to support the model hypothesis.     

固定化包埋亚硝酸菌短程脱氮与同步除磷工艺研究

为实现常温下低碳源城市生活污水的低能耗脱氮除磷,采用固定化技术和厌氧/好氧/缺氧(AOA)工艺耦合与游离组进行了对比实验研究。在温度为25±1℃、pH为8.0±1、DO为1±0.5 mg/L和HRT为9 h的条件下,两组运行结果表明,固定组具有较高的硝化效率和较强的适应能力,亚硝氮的积累率可以稳定维持在70%以上,对NH4+-N、COD和TP的去除率分别为92.2%、87.2%和81.3%,明显优于游离组。     

基于PROMETHEEⅡ法的污染场地土壤修复技术筛选及应用

依据当前污染场地土壤修复技术特点以及场地特征,构建4层12指标21方案的污染土壤修复技术决策分析结构,运用多属性决策分析方法——PROMETHEEⅡ偏好排序法,对当前场地修复技术以及典型场地条件进行了客观分析和综合评价,实现基于具体修复目标的污染场地土壤修复技术择优筛选,并采用该方法对虚拟特定污染场地的土壤修复技术筛选进行了实例应用。这为污染场地的治理和修复提供了方法依据和理论参考。     

澳大利亚碳交易体系下的经济援助系统

澳大利亚碳交易机制正式实施,配套的经济援助系统为其提供了合理、合法、全方位的保障措施,为企业转向清洁生产提供良好的过度环境。援助系统主要分为工业援助与居民援助两大部分,对澳大利亚碳交易机制的经济扰动进行了系统调节。这些援助系统的设计优点可为中国碳交易市场建设提供经验借鉴。     

不同类型生物活性滤床对诺氟沙星的去除

诺氟沙星作为一种抗生素广泛应用于人类日常生活，并大量进入水体环境，给水环境质量和生态系统安全带来隐患。研究了由3种不同填料组成的水平流和复合垂直流生物活性滤床对诺氟沙星的去除效果，结果表明，在水力负荷为0．1m^3／（m^2·d）、进水诺氟沙星浓度为392．11—686．17μg／L（平均浓度为500．97μg／L）条件下，复合垂直流滤床对诺氟沙星去除效果普遍好于水平潜流滤床，以沸石为填料的复合垂直流生物活性滤床对诺氟沙星的去除效果最好，平均去除率为80．61％，说明选择合适填料和合适类型的生物活性滤床可以作为去除诺氟沙星的一种有效方法。     

含硝基苯、苯胺废水处理的工程实践

采用固定化微生物-曝气生物滤池与铁-炭微电解法联用的工艺方法处理含硝基苯、苯胺的废水。通过培养驯化微生物阶段、半负荷进水阶段、满负荷进水阶段的调试运行,表明:当进水CODCr<1 000mg/L、硝基苯<120mg/L、苯胺<30mg/L时,出水可达到CODCr<300mg/L、硝基苯<5mg/L、苯胺<5mg/L的设计要求。铁-炭微电解法在pH值为3～4时,对废水有一定的脱色作用,但pH值升高后脱色效果不明显。     

广州市在用机动车排气抽检工作若干问题探讨

介绍了广州市在用机动车抽检工作情况和程序,分析了排气抽检工作中存在的问题,提出了解决问题的建议和方法。