氧氟沙星在沉积物-水界面上的降解动力学研究

氧氟沙星大量进入水环境,具有较高的生态风险.探明氧氟沙星在沉积物-水界面上的降解规律有助于对其水环境污染进行控制.本研究探索了从沉积物中提取和测定氧氟沙星的方法,研究了其在沉积物-水界面上的降解动力学过程以及微生物对该过程的影响.研究结果表明利用1:1的乙腈和Mcllvina缓冲溶液(p H=10)可以从沉积物中有效提取氧氟沙星,提取回收率大于90%.降解动力学结果显示:在微生物抑制条件下,氧氟沙星降解微弱;在微生物未抑制条件下氧氟沙星的降解基本符合一级动力学和二级动力学过程,半衰期分别为10.1天和7.2天.研究暗示可以通过工程措施增强水环境中微生物的群落多样性和活性,达到促进水体中氧氟沙星的降解、降低环境风险的目的.     

棘洪滩水库沉积物对上覆水氮磷营养盐的影响

为了解青岛棘洪滩水库沉积物对水库水质的影响,分别在水库进水口（JSK）、库区中心（KX）和出水口（CSK）3个采样点采集库区沉积物,通过静态模拟吸附/释放实验,分析上覆水中氮磷营养盐含量变化.结果表明,除亚硝酸盐表现出微弱释放作用外,库区沉积物对氨氮、硝酸盐氮、总氮和总磷均表现出吸附作用,是氮磷营养盐的“汇”,并且不同采样点吸附能力也存在差异.其中出水口沉积物对总氮吸附作用最明显,吸附速率为4.80mg/（kg·d）,进水口沉积物对总磷吸附作用最强,吸附速率为0.06mg/（kg·d）.由此得出棘洪滩水库库区沉积物不会增加上覆水营养盐含量,库区水体营养盐可能主要来自引水.     

使用离散的气-水界面模拟裂隙网络非饱和渗流

非饱和带裂隙中的饱和区和排干区可以用一个离散的气-水界面分隔开。此气-水界面的位置可以用边界元数值方法通过迭代确定，这样就可以实现对单裂隙内非饱和渗流的描述。将此数值方法推广到裂隙网络中，为用离散裂隙网络模型模拟裂隙岩体非饱和渗流提供了初步的框架。几个算例的计算结果验证了计算程序的正确性。     

沉积物中磷的迁移转化过程论述

磷是造成水体富营养化的限制因子之一.在有效控制外源磷输入造成的污染时,沉积物中的内源磷成为污染主体,内源磷的释放对水体持续富营养化状态所产生的作用逐渐凸显.沉积物中内源磷的释放增大了湖泊、河流等生态系统的水体发生富营养化的风险,明晰沉积物中磷的迁移转化过程对改善水体富营养化现象具有重要意义.总结了沉积物和间隙水中磷的形...     

PAC絮凝沉积藻量对水-底泥系统营养盐释放的影响

聚合氯化铝(PAC)絮凝除藻对降低水体藻密度效果显著,但絮凝形成的沉积藻量对水-底泥系统营养盐释放的影响鲜有报道。通过监测不同量的絮凝藻沉积于一定量的底泥表面时上覆水水质和底泥组成的变化,探究使用PAC絮凝除藻时沉积藻量对水体水质及底泥内源释放的影响。结果表明,沉积藻会显著增加底泥中的氮向上覆水释放,当泥与藻的干质量之比为167. 2、83. 6和41. 8时,反应器上覆水中NH₄⁺-N浓度均值分别为控制反应器(CK)的2. 86、2. 42和1. 43倍,对应TN浓度均值分别为CK的2. 06、1. 66和1. 09倍。此外,沉积藻会促进泥水界面处的反硝化过程,促进效果与沉积藻量呈负相关。然而,沉积藻对于控制底泥磷释放具有积极作用,试验期间CK上覆水中TP和PO₄^3--P浓度均值分别为0. 35和0. 22 mg/L,而覆有沉积藻的所有反应器中TP和PO₄^3--P浓度均值分别都低于0. 05和0. 03 mg/L,且沉积藻量越大,对应的磷浓度越低。     

动水条件下重金属在沉积物水之间的迁移规律

借助自主开发的不同水动力模拟水槽,选择4.01 cm/s（小流速, A槽）、12.70 cm/s（中流速,B 槽）、20.23 cm/s（大流速,C槽）3种流速条件,研究15 d运行周期内, 3个水槽中沉积物重金属Cd、Cr及类金属As在沉积物间隙水上覆水之间的迁移规律。结果表明：1）流速的增加能促进重金属的释放;2）间隙水中As的浓度远远大于上覆水中浓度,为其向上覆水迁移提供了条件;3）沉积物再悬浮是上覆水中重金属浓度增加的主要原因。同时,与静水条件相比,动水条件对沉积物中重金属的迁移有显著影响,但不同重金属受自身特性的影响显示不同的迁移规律。另一方面,3种水流条件对不同介质中重金属含量变化产生的影响过程和结果也不相同,但其影响程度总体为上覆水>沉积物>间隙水。     

城市滨水界面的场所性塑造途径研究

在分析滨水界面的功能特征的基础上,提出城市滨水界面的场所性塑造的途径,以实现城市滨水界面的健康发展,并为未来滨水区的开发、改造等实践提供理论基础。     

混凝土芯水泥土复合桩混凝土-水泥土界面摩擦特性试验研究

混凝土芯水泥土复合桩是由高强度混凝土芯桩和水泥土组成的新型复合桩。芯桩-水泥土以及水泥土-桩周土之间的界面摩擦特性是影响复合桩荷载传递规律的关键因素,目前对芯桩-水泥土界面摩擦特性的研究还较少,而且常规的二维平面剪切试验也无法研究芯桩的直径和截面形状等因素对界面特性的影响。文章采用自主研发的三维桩土接触面剪切试验装置,模拟工程实际情况,对预制混凝土芯桩-水泥土界面摩擦特性进行研究。剪切试验结果表明：混凝土-水泥土界面在剪切试验过程中经历了弹性阶段、脆性破坏阶段和剪切滑移三个阶段,采用三折线模型可以较好地描述其本构关系;界面极限侧摩阻力与芯桩含芯率(或直径)密切相关,随含芯率增加表现为先大幅减小而后逐步趋于稳定;界面极限侧摩阻力与水泥土无侧限抗压强度存在近似线性关系,其值约为水泥土无侧限抗压强度的0.064～0.259倍,而界面残余侧摩阻力受含芯率和水泥土养护龄期的影响相对小;在芯桩侧表面积相同的情况下,圆芯复合桩界面极限侧摩阻力约为方芯复合桩的1.329倍;界面极限相对位移受含芯率、水泥土龄期及芯桩截面形状影响较小,基本在1.23～2.40mm。     

考虑超孔隙水压力的桩土界面直剪试验研究

采用大型恒刚度直剪仪,系统研究超孔隙水压力对黏性土中桩土界面剪切性能的影响。根据制定的测试超孔隙水压力方案,对4个粗糙度等级(混凝土表面锯齿状峰谷距为0、2、4、6mm)的不同含水率黏性土中桩土界面在不同剪切速率下进行剪切试验。针对界面粗糙度、黏性土含水率、剪切速率3个变化参数对界面抗剪强度的影响进行分析。结果表明：界面粗糙度越大,界面超孔隙水压力越小,有效法向应力越大,黏性土颗粒与混凝土表面吸附性越大,桩土界面抗剪强度越大;黏性土含水率越大,界面超孔隙水压力越大,有效法向应力越小,黏性土颗粒与混凝土表面吸附性不能完全发挥,桩土界面抗剪强度反而减小;在剪切速率0.4~1.0mm/min范围内,剪切速率越大,界面超孔隙水压力增幅较小,有效法向应力变化不大,桩土界面抗剪强度虽有减小,但不同剪切速率下超孔隙水压力对桩土界面抗剪强度的影响不明显。     

新老混凝土粘结界面的微结构及与集料-水泥界面的差异

新老混凝土粘结界面的性能在很大程度上将由其微观结构来决定。在大量宏观和微观试验研究的基础上 ,提出了粘结界面的微结构模型 ,并分析了微结构的生成机理、组成和形貌特征。与已有较多研究的集料 -水泥界面模型进行了进一步对比 ,指出了它们之间的重要差异。最后分析了微结构与宏观力学性能的关系     

菲律宾蛤仔育苗用水系统中的细菌分布和周年变化特征

于2005年对大连庄河海量集团菲律宾蛤仔Ruditapes philippinarum育苗系统沉淀池、砂滤池几类不同功能细菌数量的变化进行了调查研究。结果表明:砂滤池出口水中的异养菌、氨化细菌、弧菌、亚硝化细菌数量均与沉淀池出口水中差异不明显;沉淀池水中的细菌数量均比泥中低,但不低于1个数量级。水和泥中的异养菌、弧菌最高值出现时间一致,分别出现在4月末和5月末;水中的亚硝化细菌最高值出现在7⁸月,泥中的出现在8月下旬8月,泥中的出现在8月下旬⁹月中旬;水中的氨化细菌最高值出现在8月下旬9月中旬;水中的氨化细菌最高值出现在8月下旬⁹月中旬,泥中的出现在9月中旬9月中旬,泥中的出现在9月中旬¹0上旬;泥中的反硝化、反硫化细菌最高值出现在610上旬;泥中的反硝化、反硫化细菌最高值出现在6⁹月。从异养细菌的数量看,沉淀池水质达到富营养化水平。     

地方高校油画教育探究

油画教育是高校美术教学的一部分,正处于快速发展的阶段,也取得了一定的效果。为进一步推进地方高校油画教育的发展,取得更好的教学效果,需要准确把握地方高校油画教学现状和存在的问题,在此基础上优化油画教学理念、教学方法和教学内容,为油画教育的创新发展提供思路。     

海州湾生态修复效果评价

为评价海州湾生态修复工程实施的效果,在分析2014年春、夏、秋3个季节本底调查数据的基础上,以"资源—环境"作为准则层,共筛选16项具体的评价因子建立生态修复效果评价指标体系,并用德尔菲法和熵权法组合赋权,通过效用函数估算海州湾生态修复治理目标的实现程度。结果表明:通过投放人工鱼礁,海州湾生态修复率达到30.14%,其中,生物资源平均修复率为17.96%,海洋环境平均修复率为33.15%,生态修复治理目标综合值为0.400 2,综合修复等级为中等。研究表明,海州湾生态修复工程对水质环境的改善效果较为明显,但对生物资源的恢复效果还有待进一步提高。     

Limiting nutrients of phytoplankton community in Hiroshima Bay,Japan

Ratios of DIN:DIP, indigenous algal assay and nitrogen fixation by phytoplankton were determined to estimate the limiting nutrient for phytoplankton growth in Hiroshima Bay, Seto Inland Sea, Japan. The algal assay was performed using indigenous pico-, nano- and microphytoplankton assemblages fractionated by filtration. Nitrogen fixation was determined using an acetylene reduction method. The DIN:DIP ratio in the study area was above 16:1 (Redfield ratio) in August 1993 and May 1994. However, in other months, the ratio was below 16:1. These values suggest that the growth of phytoplankton community is limited by nitrogen, with an exceptional phosphorus limitation in August 1993 and May 1994. Nutrient enrichment algal assay of size-fractionated phytoplankton community also supported these findings. The growth of picophytoplankton fraction was stimulated by phosphorus addition in August 1993 and May 1994, while nano- and microphytoplankton fractions were stimulated by nitrogen addition in almost all months during the study period. No nitrogen fixation by phytoplankton was detected during the study period. The results suggest that nitrogen rather than phosphorus is the limiting nutrient for the growth of the whole phytoplankton community, but picophytoplankton by itself, tends to be limited by phosphorus compared to other large-size phytoplankton when high DIN:DIP ratio was observed.     

Heavy metal fluxes at the sediment-water interface of three coastal ecosystems from south-west of the Iberian Peninsula

Concentrations of the heavy metals Cr, Cu, Fe and Mn were measured in sediments and porewater samples collected in three coastal ecosystems southwest of the Iberian Peninsula: the Odiel and Barbate River Salt Marshes and the Bay of Cadiz. Both the sediment and the porewater metal concentrations in the Odiel River Salt Marshes are higher than the values found in the Bay of Cadiz and Barbate River Salt Marsh, particularly for copper, a metal associated with mining activity. In porewater, the profiles were not the same as those in the solid phase and reflect the different behaviours of the elements in relation to the redox conditions. The heavy metals Cr and Cu show a typical enrichment in the porewater of the oxic zone. The heavy metals Mn and Fe show an increase in the porewater at the depths where the maximum nitrate and phosphate concentrations occur, respectively. Significant differences between background levels for each heavy metal in the various studied zones exist. Iron and Cu showed larger background levels in the Odiel River Salt Marshes than those in the Cadiz Bay and the Barbate River Salt Marshes. In the Bay of Cadiz the background levels are also high, particularly for Cr. At the Odiel River Salt Marshes the diffusive flux of Cu is high (1.3-230.1 microg cm(-2) year(-1)), which suggests that the Odiel River Salt Marshes are subject to strong contamination by Cu, which is presumably introduced to the sediment in particulate form. In the Bay of Cadiz, Cr is the only metal with positive diffusive flux (2.15 microg cm(-2) year(-1)). It is higher than those obtained in other coastal ecosystems including the Odiel River Salt Marshes. The positive diffusive flux of Cr has been associated with the input of this metal by the naval industry and the manufacturing of car and aircraft components.     

Importance of monsoon rainfall in mass fluxes of filtered and unfiltered mercury in Gwangyang Bay, Korea

We investigated the effects of the East Asian Summer Monsoon (EASM), which brings approximately half of Korea's annual rainfall in July, on the concentration and particle-water partitioning, and sources of Hg in coastal waters. Surface seawater samples were collected from eight sites in Gwangyang Bay, Korea, during the monsoon (July, 2009) and non-monsoon dry (April and November, 2009) seasons and the concentrations of suspended particulate matter, chlorophyll-a, and unfiltered and filtered Hg were determined. We found significant (p < 0.05) increases in filtered Hg in the monsoon season (1.8 ± 0.019 pM) compared to the dry season (0.62 ± 0.047 pM). In contrast, the Hg concentrations associated with particles showed no significant differences (p > 0.05) between the monsoon (459 ± 141 pmol g^− 1) and the dry season (346 ± 30 pmol g^− 1), which resulted in decreased particle-water partition coefficients of Hg in the monsoon season compared to the values in the dry season: 5.7 ± 0.1 in April, 5.3 ± 0.1 in July, and 5.8 ± 0.1 in November. The annual Hg input to Gwangyang Bay was estimated at 64 ± 6.6 mol yr^− 1 and 27 ± 1.9 mol yr^− 1 for unfiltered and filtered Hg, respectively. The Hg discharged from rivers was a major source of Hg in Gwangyang Bay: the river input contributed 83 ± 13% of total input of unfiltered and 73 ± 6.0% of filtered Hg. On a monthly basis, unfiltered Hg input was 17 ± 11 mol month^− 1 in the monsoon season and 3.2 ± 0.70 mol month^− 1 in the dry season, while filtered Hg input was 7.1 ± 4.1 mol month^− 1 in the monsoon and 1.3 ± 0.26 mol month^− 1 in the dry. Consequently, the EASM resulted in an unfiltered Hg input 5.3 times greater than the mean dry month input and a filtered Hg input 5.5 times greater than the mean dry month input, which is mainly attributable to enhanced river water discharge during the monsoon season.     

聚羧酸系外加剂在杭州湾跨海大桥工程海工高耐久砼中的应用

海工高耐久砼为提高砼抗Cl-渗透性以达到海港工程砼结构防腐蚀、高耐久，需大量掺加粉煤灰、磨细矿粉、硅粉等掺合料，聚羧酸系外加剂以其适合低水胶比下砼大掺量掺合料的使用而备受关注。本文介绍了聚羧酸系外加剂JM—PCA(I)砼超塑化剂在杭州湾跨海大桥工程以Cl-扩散系数为主要设计技术指标的海工高耐久砼中的应用。     

Atmospheric deposition of carbon and nutrients across an arid metropolitan area

Urbanization is increasing rapidly in semi-arid environments and is predicted to alter atmospheric deposition of nutrients and pollutants to cities as well as to ecosystems downwind. We examined patterns of wet and coarse dry deposition chemistry over a five-year period at 7 sites across the Central Arizona-Phoenix (CAP) study area, one of two urban sites within the National Science Foundation's Long-Term Ecological Research (LTER) program. Wet and dry deposition of organic carbon (oC) were significantly elevated in the urban core; in contrast, mean annual wet and dry fluxes of nitrogen (N) were low (<6 kg ha(-1) yr(-1)) compared to previous estimates and did not differ significantly among sites. Wet deposition of sulfate (SO(4)2-) was high across CAP (mean 1.39 kg ha(-1) yr(-1) as S) and represented the dominant anion in rainfall. Dry deposition rates did not show strong seasonal trends with the exception of oC, which was 3-fold higher in winter than in summer; ammonium (NH4+) deposition was high but more variable. Dry deposition of NO3- and oC was strongly correlated with particulate base cations and dust-derived soluble reactive phosphorus (SRP), suggesting that urban-derived dust is scrubbing the atmosphere of acidic gases and entrained particles and increasing local deposition. Differences between measured and predicted rates of dry N deposition to the urban core may be explained by incomplete collection of gas phase N on surrogate deposition surfaces in this hot and arid environment. The extent of urban enhancement of cations and oC inputs to desert ecosystems appears to be restricted to the urbanized metropolitan area rather than extending far downwind, although a low number of sites make it difficult to resolve this spatial pattern. Nevertheless, wet and dry inputs may be important for biogeochemical cycles in nutrient and carbon-poor desert ecosystems within and near arid cities.     

The stability of marine sediments at a tidal basin in San Francisco Bay amended with activated carbon for sequestration of organic contaminants

Recent laboratory studies show that adding activated carbon to marine sediments reduces the bioavailability of persistent organic contaminants, such as polychlorinated biphenyls, to benthic organisms. The present work investigates how mixing activated carbon into cohesive sediment affects the stability of sediment obtained from the intertidal zone at the Hunters Point Naval Shipyard Superfund site in South Basin, San Francisco Bay, CA. Our results show for these sediments that mixing activated carbon into sediment does not significantly affect stability of surface sediments, as measured by sediment erosion rate and critical shear stress for incipient motion, thus supporting the potential field application of this technique for in situ stabilization of persistent organic contaminants. Hydrodynamic modeling was used to estimate the maximum bottom shear stress encountered during high-wind storm events at the estuarine inlet from which the sediments were obtained. Comparison of estimated bottom shear stresses with measured critical shear stresses shows that surface sediments will not erode under normal, non-storm conditions. Bottom shear stresses caused by large waves under infrequent high-wind storm conditions may erode surface sediments for short periods of time. We conclude from sediment stability tests and hydrodynamic modeling that mixing activated carbon amendment with cohesive sediment at selected locations within South Basin will not reduce surface sediment stability nor result in significant erosion of treated sediments.     

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.