探索波浪

海洋蕴藏能量,有时甚至是巨大的能量。拍打在太平洋海岸上的波浪尤为有力。海洋风产生波浪,它们远距离携带能量横穿太平洋。波浪也带来沉积物,形成海滩。但是这些特征不能长期保留,后面的波浪会再次改变海岸线。     

富春江(富阳段)表层沉积物中生源物质的分布特征

针对富春江(富阳段)水污染现状,对富春江(富阳段)的洋浦、永济浦和大源溪三个主要排污口附近的沉积物进行系统研究。结果表明,受污染沉积物的有机质含量为41.6～294.2g/kg,平均为145.3g/kg;凯氏氮含量为1.2～5.2g/kg,平均为2.6g/kg;总磷含量为817-1415μg/g,平均为1050μg/g。沉积物有机质、总氮、总磷水平对研究区底栖生物群落和生态环境构成了较大威胁。沉积物的有机质和凯氏氮含量受排污口影响明显;但沉积物总磷含量受排污口影响不明显。生源物质之间以及生源物质与沉积物理化性质的相关性分析表明,沉积物碳、氮以及粉砂粒存在同源性,沉积物磷与碳、氮以及粉砂粒不具有同源性,关于该区域磷素污染源还需进一步调研确认。     

火星远古曾有超级喷泉

正地球上存在一些天然的喷泉,比如美国黄石公园有一处喷泉,它能把滚烫的泉水喷射到45米的高空。然而,与火星上的远古喷泉相比,地球上的喷泉就像是小不点儿。英国研究人员推测,火星上曾有巨大的超级喷泉,可把冰雹和泥浆喷射到8000米的高空中,场面十分壮观。超级喷泉的动力来自二氧化碳。火星岩层曾经把大量的二氧化碳压缩在地下水中。这些地下水像汽水饮料一样不是很稳定,一有机会就会喷射出来。当火星地表有裂缝形成时,被压缩的二氧化碳就会大量冒出来,带动水和砂石形成超级喷泉。喷涌而出的泥浆降落到地面上,形成泥流。后来水被蒸发干后,只剩下喷泉产生的沉积物,形成类似流动的山脊岩层。     

黄土的万卷书——刘东生院士和他的黄土研究

中国科学院院士、中科院地质与地球物理研究所研究员刘东生于 2 0 0 4年 2月 2 0日获 2 0 0 3年度国家最高科学技术奖。刘东生院士还于 2 0 0 2年 4月获得世界环境科学最高荣誉、“环境科学的诺贝尔奖”———泰勒奖。本刊特刊载三思科学报道编辑碧声对刘院士和他的学生郭正堂教授的专访。     

合肥市饮用水源地沉积物重金属生态风险评价与来源解析

选取合肥市饮用水源地董铺-大房郢水库沉积物为研究对象,在该区域采集了 18个沉积物样品,分别测定了 8种重金属Cr、Ni、Cu、Zn、As、Cd、Pb、Hg的质量分数.分别采用沉积物质量基准法和潜在生态风险指数法评估其污染状况及生态风险,并通过多元统计分析和正定矩阵因子模型(PMF)对其可能来源进行解析.结果表明:研究...     

苏州河底泥重金属形态分析

Nine elements （As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn） in sediment samples at 7 sites （Site 1-7） from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference （BCR） （sequential extraction （SE）） protocol and simultaneously extracted metals （SEM）/acid volatile sulfide （AVS） procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 （Site 5） was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction （more than 50%）. While Cd, Ni and Zn （more than 35%） were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni （〉 40%） were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high Dorewater concentration.     

X射线荧光光谱法测定沉积物中重金属

以大庆市贴不贴纳污湿地为例,研究纳污湿地沉积物重金属污染.在用X射线荧光光谱法测定纳污湿地沉积物中重金属时,为检测实验分析的可靠性,随机抽取了12个样品做5次重复实验,其中:Cd、Hg、Cr、Zn的相对标准偏差均小于5%;Cu和Pb的相对标准偏差均小于10%;Cr和Ni的相对偏差均小于20%.结果表明,X射线荧光法测定样品,不需对固体样品进行消化处理,操作简便,可以同时测定多种元素,效率较高,而且是一种非破坏性的分析方法,样品可重复利用.     

星云湖水体及表层沉积物中磷的空间分布特征及差异性分析

通过现场调查和实验室分析方法对星云湖水体及表层沉积物各形态磷的空间分布特征及差异性进行分析.结果表明,星云湖表层水体各形态磷在空间上表现出明显的分异性,磷的浓度总体呈现从北向南逐渐升高的趋势.而底层水体各形态磷空间差异较小,全湖无明显变化趋势.表层沉积物中总磷以无机磷为主,占总磷的64.61%～90.79%,呈现从北向南逐渐递减的趋势,有机磷含量相对较低.无机磷中各形态磷的含量由高到低依次是Ca-P>Fe/Al-P>NH4Cl-P.     

Bacterial and archaeal communities in the surface sediment from the northern slope of the South China Sea

Microbial diversity of sediments from the northern slope of the South China Sea was studied by constructing bacterial and archaeal 16S rRNA gene clone libraries. Fourteen bacterial phylogenetic groups were detected, including Gammaproteo-bacteria, Deltaproteobacteria, Planctomycetes, Alphaproteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, Chloroflexi, Acidobacteria, Betaproteobacteria, Nitrospirae, candidate divisions OP8 and OP11, and an unknown group. Gammaproteobacteria was the predominant group in bacterial libraries with the percentage ranging from 31.8% to 63.2%. However, archaeal libraries had relatively lower diversity, with most clones belonging to marine archaeal group I uncultured Crenarchaeota. In addition, two novel euryarchaeal clones were detected not to match any culture-dependent or -independent isolates. Compared with other gas hydrate-rich ecosystems and different areas of the South China Sea, a distinct microbial community was revealed in this study.