乳山湾邻近海域沉积物中好氧氨氧化微生物分布特征

氮素循环是海洋生态系统物质循环的重要组成部分,对维持海洋生态平衡具有重要意义.由好氧氨氧化微生物(aerobic ammonia-oxidizing microorganism,AOM)推动的氨氧化过程是硝化作用的限速步骤.本研究通过荧光定量PCR技术,并结合潜在硝化速率(potential nitrification rates,PNR)的测定,研究了2014年8月乳山湾邻近海域沉积物中好氧氨氧化微生物种群分布特征.结果表明,3个采样站位中氨氧化细菌(ammonia-oxidizing bacteria,AOB)amo A拷贝数均高于氨氧化古菌(ammonia-oxidizing archaea,AOA);活性AOB占总AOB的比值低于1%,而活性AOA未检出;添加可抑制AOB活性的氨苄青霉素后,潜在硝化速率显著降低(P0.05).由此可知,AOB在8月乳山湾邻近海域沉积物氨氧化过程中发挥了重要作用.溶解氧浓度、温度及铵盐浓度对乳山湾邻近海域沉积物中好氧氨氧化微生物的种群丰度起着重要的调控作用.     

不同涂层电极和抑制剂对电化学氧化降解苯酚的影响

采用热分解法和电沉积法2种工艺制得4个二氧化铅电极,用扫描电镜（SEM）观察了电极表面形貌.以水杨酸(2-HBA)为捕获剂,用高效液相色谱仪测定羟基自由基与水杨酸的羟基化产物2,5-二羟基苯甲酸(2,5-DHBA)的量作为产生的羟基自由基的浓度.通过羟基自由基的浓度的测定和苯酚的降解,研究了不同涂层电极和抑制剂对电化学氧化对苯酚降解的影响.热分解电极、无掺杂电极、掺铋电极和掺镧电极产生羟基自由基的最大浓度分别为0.781、1.048、1.838、2.044 μmol/L,以这4个电极为阳极对苯酚进行电解, 1.5　h苯酚去除率分别为87.30%、93.55%、97.95%、98.70%,5　h　TOC去除率分别为86.75%、94.26%、98.53%、99.60%;以掺镧电极为阳极,加入抑制剂CO^2-₃、PO^3-₄、CH₃ＣＯＯ^-产生的羟基自由基的最大浓度分别为无检出、0.170 μmol/L、0.270 μmol/L,对苯酚进行电解,5 h苯酚去除率分别为99.06%、99.98%、99.79%.电沉积法制得电极对苯酚的降解效果优于热分解法制得的电极,而掺杂的电极优于无掺杂的电极,掺镧电极对苯酚降解效果最好,抑制剂CO^2-₃、PO^3-₄、CH₃ＣＯＯ^-存在时会对苯酚的降解起到阻碍作用,CO^2-₃阻碍作用最强.不同制备方法和掺杂不同添加剂制得的电极的催化性能不同,对苯酚的降解效果也不同;羟基自由基的浓度越大,苯酚的降解效果越好,抑制剂捕获了产生的羟基自由基,不利于苯酚的降解.     

调水调沙对黄河下游营养盐变化规律的影响

根据黄河首次调水调沙期间(2002年7月)和2002年在黄河利津站对营养盐的月际观测结果,系统分析了2002年黄河首次调水调沙期间黄河利津站和全年溶解无机态营养盐的变化,讨论了营养盐与水情要素之间的相互关系,计算了调水调沙期间及全年营养盐入海通量,并和历史资料作了比较.结果表明,调水调沙期间NO_3~-N、NO_2~--N、NH_4~+-N浓度的变化范围分别为169.3～273.2、 0.08～0.84、 1.39～5.04 μmol·dm~(-3),平均浓度分别为218.6、 0.16、 2.27 μmol·dm~(-3);PO_4~(3-)-P、 SiO_3~(2-)-Si浓度的变化范围为0.36～0.56、 161.4～195.8 μmol·dm～-3,平均浓度分别为0.48、 166.7 μmol·dm~(-3).在调水调沙期间,NO_3~--N浓度与水量无显著相关性,PO_4~(3-)-P浓度与水沙均无显著相关性,而SiO_3~(2-)-Si浓度与沙量呈显著正相关.与历史资料相比,调水调沙对黄河下游溶解态无机营养盐浓度在全年的变化规律并无明显影响.但黄河首次调水调沙短短不到一个月的时间,所输送的营养盐通量便占到当年输送通量的一半左右.调水调沙对营养盐输送通量在年内的分配产生重大影响,使得黄河营养盐向河口的输送非常集中.     

赤潮藻电致化学发光分子探针检测系统的构建

为建立一种赤潮藻电致化学发光分子探针检测新技术(electrochemiluminescence-molecular probe,ECL-MP),本课题组根据电致化学发光(electrochemiluminescence,ECL)检测微量物质的原理及相关文献,自行构建了一台ECL检测装置,并对其工作性能及最适工作条件进行反复测试.结果表明,该装置能够正常工作,在电压1.0 V,电流1.0 mA,TPrA浓度1.5 mol.L-1及磷酸盐缓冲液pH 7.4的条件下对Ru(bpy)3Cl2.6H2O达到最优检测,检测限为10-11mol.L-1,线性分析范围10-9～10-5mol.L-1,可检测的物质的量范围0.4 pmol～4 nmol,跨越5个数量级.该装置灵敏度高,工作稳定,为建立赤潮藻ECL-MP技术打下了坚实的基础.     

青藏高原纳木错和安多牧区室内空气污染研究

2009年夏季在青藏高原纳木错和安多牧区对牧民帐篷内细颗粒(PM2.5)浓度和一氧化碳(CO)的含量进行了观测,以认识牧区室内空气中PM2.5和CO的污染水平、日变化特征及主要影响因素,以及不同人群在污染物中的暴露水平.观测结果表明,未安装烟囱的帐篷内PM2.5浓度和CO平均含量(体积分数)分别为1.272 mg·m-...     

河套平原O3浓度时空分布、传输路径及潜在源贡献分析

基于2005—2020年OMI遥感卫星O₃柱浓度数据,结合河套平原23个国控点环境自动监测站大气污染物数据和全球资料同化系统（GDAS）气象资料,探讨河套平原O₃污染时空分布特征、气象因素、传输路径和潜在来源.结果表明：（1）2005—2020年河套平原O₃柱浓度年均值波动上升,年均增长率为2.95%,季节变化表现为春季>冬季>夏季>秋季;（2）空间分布方面：高值区主要分布在东北部地区,南部城市低于北部城市;（3）河套平原地区O₃浓度与气温、日照呈显著正相关,与气压呈显著负相关,而降水、相对湿度、风速对O₃浓度影响具有显著的区域性差异;（4）基于后向轨迹HYSPLIT模型对河套平原地区污染严重城市鄂尔多斯市进行分析,发现远距离气流传输主要来自西北方向,近距离气流传输主要来自西南方向;O₃主要潜在贡献源区存在一定的季节差异：春季主要来自陕西北部与包头市,夏季主要来自陕西北部与山西西部,秋季主要来自内蒙古西部与宁夏银川市、陕西北部,而冬季则主...     

Respiratory and behavioral responses of the grass shrimp Palaemonetes pugio to cadmium and reduced dissolved oxygen

Adult grass shrimp (Palaemonetes pugio) were collected during July and August, 1973, and exposed for 48-h periods to a series of sublethal cadmium (Cd) concentrations: 0.1 and 0.56 mg l^-1 for metabolic studies; and 0.01, 0.05, 0.1, 0.3, 0.56 mg l^-1 for locomotor studies. Treatment effects were tested singly and in combination at selected dissolved oxygen (DO) concentrations ranging from near saturation to 0.8 mgl^-1. Shrimp not exposed to Cd exhibited metabolic regulation between 6.5 and, 4.6 mg DOl^-1, with progressively lower O₂ consumption rates at lower DO concentrations. Oxygen consumption of Cd-exposed shrimp was suppressed overall relative to the non-Cd treated shrimp, and with one exception, the magnitude of metabolic suppression directly corresponded to Cd concentration. Locomotor activity of non-Cd exposed shrimp was relatively independent of DO concentration down to 2.8 mg DO l^-1 and became significantly suppressed at 1.8 mg DO l^-1 and below. Significant suppression of locomotion was evident in shrimp exposed to 0.56 mg Cd l^-1, but was not seen in treatment groups of 0.3 mg Cd l^-1 or lower. No interaction on locomotor activity of shrimp was detected between Cd exposure and oxygen concentration. The reduction of locomotor activity and metabolism at 0.56 mg Cd l^-1 exposure is similar to that occurring under reduced oxygen condition. It is hypothesized that Cd acts in some manner to suppress O₂ availability to P. pugio, a suggestion consistent with literature reports on adverse effects of Cd on fish respiratory enzymes and gill tissue.Contribution No. 351 of the U.S. Environmental Protection Agency, Environmental Research Laboratory, Narragansett, Rhode Island. Although the research described in this article was funded by the U.S. Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred     

Indirect effects of a key ecosystem engineer alter survival and growth of foundation coral species

Stegastes nigricans, a "farmerfish" that cultivates algal turf and defends territories from grazers and other intruders, can affect coral indirectly due to increased competition with farmed algal turf and/or reduced predation resulting from territorial aggression directed at corallivores. To investigate the indirect effects of this key ecosystem engineer on coral mortality and growth, we transplanted caged and exposed fragments of four coral species to patch reefs in French Polynesia on which we manipulated the presence of S. nigricans and turf, and to reefs naturally devoid of S. nigricans. Reef access was two to four times higher for herbivorous fishes, and two times higher for corallivorous fishes, when S. nigricans was removed, indicating that reef access is reduced for two important guilds of fishes when S. nigricans is present. Stegastes' territoriality indirectly benefited delicate acroporids (Montipora floweri and Acropora striata), yielding a twofold to fivefold reduction in skeletal loss due to lower predation frequencies in the presence of S. nigricans. Three corals, A. striata, M. floweri, and especially Porites australiensis, suffered mortality due to overgrowth significantly more frequently in the presence of farmed turf, but Pocillopora verrucosa did not. Algal abundance predicted the frequency of overgrowth for only A. striata and P. australiensis. M. floweri were more likely to be overgrown when exposed (uncaged) in the presence of S. nigricans, suggesting an interaction modification, in this case that initial predation increased susceptibility to competition with turf. In this community, the presence of S. nigricans may increase algal overgrowth of massive Porites by facilitating its turf competitors and simultaneously reduce predation of branching corals through territorial exclusion of corallivores. These indirect interactions may underlie previously documented community transitions from disturbance-resistant massive coral to recovering branching corals within S. nigricans territories.