大气气溶胶中若干有机物的含量和季节变化   总被引：4，自引：2，他引：2  

张志强  徐少才  王燕 《中国海洋大学学报(自然科学版)》2005,35(4):661-664,628

研究、探讨青岛近岸大气气溶胶中多芳烃类化合物的浓度水平、变化特征及影响因素。用高效液相色谱荧光检测法分析了青岛近岸大气气溶胶中的多环芳烃(PAHs)的含量水平,共检出13种多环芳烃化合物。结果表明该类化合物总量(∑PAHs)具有明显的季节特征,呈现春季<秋季<冬季的特征,人类活动可能是其主要来源。  相似文献   

鼠尾藻(Sargassum thunbergii)对邻苯二甲酸二甲酯(DMP)胁迫的响应     

吕芳  丁刚  王翔宇  房慧  吴海一 《海洋与湖沼》2017,48(2):336-342

邻苯二甲酸二甲酯(dimethyl phthalate,DMP)是近海环境有机污染物之一,不仅对海洋生物造成毒害,且能在生物体内富集和放大,对海洋生态系统形成严重威胁。本文以鼠尾藻(Sargassum thunbergii)为研究对象,通过测定比生长速率、叶绿素a含量、光合和呼吸速率、光合基因rbcL转录水平上的相对表达量等指标,研究了鼠尾藻对不同浓度DMP的响应。结果表明,低浓度的DMP(0.lmg/L)短时间内(≤15d)能促进鼠尾藻的生长和叶绿素a的合成,并使藻体的光合作用增强,诱导光合基因rbcL的表达,而在高浓度DMP(≥0.3mg/L)的作用下,鼠尾藻的生长速率、光合和呼吸速率、rbcL基因的表达量均随着暴露时间的延长呈明显下降趋势,且DMP浓度越高,降幅越大。以上研究结果对了解DMP对鼠尾藻胁迫的影响机制奠定了基础,为保护海洋经济藻类的养殖环境提供了理论依据。  相似文献   

南海东北部分粒级叶绿素a和超微型光合生物的周日变化     

姜歆  黄良民  谭烨辉  李佳俊  柯志新  赵春宇 《海洋通报》2017,36(6):689-699

分别于2014年春、秋和2015年夏3个季节对南海东北部A站位(118°E,21.5°N)分粒级叶绿素a浓度和超微型光合生物(原绿球藻、聚球藻和超微型真核藻类)细胞丰度的昼夜变化进行了24 h时间序列连续观测和分析。通过萃取荧光法分析叶绿素a浓度,发现叶绿素a浓度呈现明显的昼夜变化,春季正午最高,秋季和夏季基本变化趋势为白天升高,夜晚降低;而因夏季中午的光抑制作用,叶绿素a的浓度相对较低。超微型光合生物(0.2~3μm)对总叶绿素a的贡献最高(71.49%),小型浮游植物(20μm)贡献率最低(10.41%)。通过流式细胞技术检测到3个超微型光合生物类群;其中,原绿球藻为优势类群,最大细胞丰度达1.05×10~5cells/m L,其次是聚球藻,超微型真核藻类的细胞丰度最低,但由于其单位细胞内的叶绿素a含量高,所以可能对叶绿素a的贡献最大。聚球藻丰度基本上白天下降,傍晚到午夜上升;秋季和夏季,超微型真核藻类的丰度白天高,夜晚低,而春季则相反;原绿球藻在秋季和春季的昼夜变化规律和超微型真核藻类相似。在多种因素共同影响下,光照是调控叶绿素a浓度和超微型光合生物丰度昼夜变化的一个关键因素。季节变化上,原绿球藻的细胞丰度季节间没有统计学差异(P0.05),聚球藻的季节变化为秋夏春,超微型真核藻类的季节变化规律和聚球藻相反。  相似文献   

基于PXRF的西南印度洋脊硫化物表层沉积物地球化学找矿研究   总被引：3，自引：0，他引：3  

廖时理  陶春辉  李怀明  张国堙  梁锦  杨伟芳 《海洋学报(英文版)》2017,36(7):66-76

海底热液喷发形成的热液羽状流中富含成矿物质,并沉淀在距离热液喷口不等的范围内。对西南印度洋中脊热液喷口附近、距离喷口中等距离、远离喷口的六个表层沉积物样品开展了不同粒度沉积物的便携式XRF（PXRF）分析。结果表明,PXRF可以有效获得的洋中脊钙质沉积物中成矿元素的富集特征。>40目的沉积物样品具有较高的Cu、Zn、Fe、Mn等元素含量,40目以下沉积物中则相对稳定,可能与粗粒沉积物中玄武岩碎屑/玻璃含量较高有关,与镜下鉴定结果一致。以热液喷口为中心,表层沉积物中表现出Cu、Zn、As、Fe、Mn的元素分带,靠近喷口的沉积物中具有较高的成矿元素的含量,并具有较高的Cu/Fe、Zn/Fe比值或者Cu/Mn与Zn/Mn比值。上述结论表明,洋中脊沉积物中成矿元素的含量主要受与喷口的距离的影响,而与粒度的关系不大,洋中脊沉积物地球化学找矿应采用40目以下粒径沉积物作为分析样品。通过PXRF获得的Cu、Zn、As、Fe、Mn等元素含量及其比值特征可以作为海底多金属硫化物沉积物地球化学找矿的指标,该方法满足快速有效识别洋中脊沉积物中地球化学异常的要求。  相似文献   

Contrasting hydrography and phytoplankton distribution in the upper layers of cyclonic eddies in the Mozambique Basin and Mozambique Channel     

T Lamont  RG Barlow 《African Journal of Marine Science》2017,39(3):293-306

Hydrographic data collected in cyclonic eddies in the Mozambique Channel and Basin revealed notable differences in temperature and salinity at a depth of 100 m, the upper mixed layer, the nitracline depths, and vertical distribution of chlorophyll-a (Chl-a). Differences in temperature and salinity did not show any consistent patterns. In contrast, the differences in the upper mixed layer, nitracline depths and the vertical Chl-a profile appeared to be driven by combined effects of eddy dynamics (i.e. shoaling of isopleths) and the seasonal variation in light availability and mixing conditions in the upper layers. Cyclonic eddies studied during austral spring and summer in the Mozambique Channel exhibited shallower upper mixed layers and nitracline depths, and deeper euphotic zones. Distinct subsurface Chl-a maxima (SCM) were associated with the stratified conditions in the upper layers of these eddies. In contrast, a cyclonic eddy studied during mid-austral winter in the Mozambique Basin had a shallower euphotic zone, deeper upper mixed layer and uniform Chl-a profiles. Another eddy sampled in the Mozambique Basin toward the end of winter showed a less pronounced SCM and roughly equal euphotic zone and upper mixed layer depths, suggestive of a transition from a well-mixed upper layer during winter to stratified conditions in summer.  相似文献   

Electron Probe Microanalysis of Bromine in Minerals and Glasses with Correction for Spectral Interference from Aluminium,and Comparison with Microbeam Synchrotron X‐Ray Fluorescence Spectrometry          下载免费PDF全文

Chao Zhang  Jinru Lin  Yuanming Pan  Renfei Feng  Renat R. Almeev  Francois Holtz 《Geostandards and Geoanalytical Research》2017,41(3):449-457

The strong spectral interference between Br‐ and Al‐induced X‐ray lines hampers the utilisation of electron probe microanalysis (EPMA) for measuring Br mass fractions in Al‐bearing minerals and glasses. Through measuring Br‐free Al‐bearing materials, we established an EPMA method to quantify the overlap from AlKα on BrLβ, which can be expressed as a linear function of the Al₂O₃ content. The count rate of the BrLβ peak signal was enhanced by high beam currents and long measurement times. Application of this EPMA method to Al‐ and Br‐bearing materials, such as sodalite and scapolite, and to five experimental glasses yielded Br mass fractions (in the range of 250–4000 μg g^?1) that are consistent with those measured by microbeam synchrotron X‐ray fluorescence (μ‐SXRF) spectrometry. The EPMA method has an estimated detection limit of ~ 100–300 μg g^?1. We propose that this method is useful for measuring Br mass fractions (hundreds to thousands of μg g^?1) in Al‐bearing minerals and glasses, including those produced in Br‐doped experiments. In addition, the natural marialitic scapolite (ON70) from Mpwapwa (Tanzania) containing homogeneously distributed high mass fractions of Br (2058 ± 56 μg g^?1) and Cl (1.98 ± 0.03% m/m) is an ideal reference material for future in situ analyses.  相似文献   

High‐temporal resolution fluvial sediment source fingerprinting with uncertainty: a Bayesian approach          下载免费PDF全文

Richard J. Cooper  Tobias Krueger  Kevin M. Hiscock  Barry G. Rawlins 《地球表面变化过程与地形》2015,40(1):78-92

This contribution addresses two developing areas of sediment fingerprinting research. Specifically, how to improve the temporal resolution of source apportionment estimates whilst minimizing analytical costs and, secondly, how to consistently quantify all perceived uncertainties associated with the sediment mixing model procedure. This first matter is tackled by using direct X‐ray fluorescence spectroscopy (XRFS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses of suspended particulate matter (SPM) covered filter papers in conjunction with automatic water samplers. This method enables SPM geochemistry to be quickly, accurately, inexpensively and non‐destructively monitored at high‐temporal resolution throughout the progression of numerous precipitation events. We then employed a Bayesian mixing model procedure to provide full characterization of spatial geochemical variability, instrument precision and residual error to yield a realistic and coherent assessment of the uncertainties associated with source apportionment estimates. Applying these methods to SPM data from the River Wensum catchment, UK, we have been able to apportion, with uncertainty, sediment contributions from eroding arable topsoils, damaged road verges and combined subsurface channel bank and agricultural field drain sources at 60‐ and 120‐minute resolution for the duration of five precipitation events. The results presented here demonstrate how combining Bayesian mixing models with the direct spectroscopic analysis of SPM‐covered filter papers can produce high‐temporal resolution source apportionment estimates that can assist with the appropriate targeting of sediment pollution mitigation measures at a catchment level. © 2015 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献   

外源硒对罗布麻幼苗生长及光合作用的影响     

吕海祥  田长彦  王梓宇  张科 《干旱区地理》2015,38(1):83-89

硒是植物生长发育的必需元素,能促进植物生长。采用盆栽试验的方法,研究了施用不同浓度的外源硒对一年生罗布麻幼苗生长及叶绿素荧光参数的影响。研究结果表明：根施（R）和叶面喷施（L）两种施硒方式下,硒浓度与罗布麻一年生幼苗生长及叶绿素荧光参数有极显著相关性,表现为,一定浓度范围内（0～1.5 mg·kg^-1）,随着硒浓度的增加,罗布麻茎干重、叶干重、株高、茎粗、主叶对数和侧枝数均有有不同程度的上升;Fv/Fm、Fv/Fo、Ψo、φEo、PIABS、均随着施硒浓度的增加而增加;V_K、V_J、V_I均随着施硒浓度的增加而逐渐下降,S_m逐渐上升;说明施硒促进了罗布麻叶PSII的活性,提高了PSII反应中心的开放程度,增大其光能利用率。但随着供应浓度的进一步提高,各项生长及荧光指标有所降低,因此过量的硒供应对于罗布麻生长不利,而且有益与有害之间的范围很小,具体罗布麻栽培中要严格控制硒用量在1～3 mg·kg^-1范围内。搜索 #SrsZzqBAngjSTips { Z-INDEX: 999999999; POSITION: absolute; WIDTH: 56px; HEIGHT: 24px; LEFT: 1342177.27em } #SrsZzqBAngjSTips A { POSITION: relative; LINE-HEIGHT: 24px; MARGIN: -32px 0px 0px; PADDING-LEFT: 23px; WIDTH: auto; DISPLAY: block; BACKGROUND: url(http://mat1.gtimg.com/www/sogou/sogou_tips_v1.png) no-repeat 0px 0px; HEIGHT: 24px; COLOR: #000; FONT-SIZE: 12px; TEXT-DECORATION: none } #SrsZzqBAngjSTips A:hover { BACKGROUND-POSITION: 0px -34px; COLOR: #45a1ea }  相似文献   

腐殖酸三维荧光光谱特性研究   总被引：53，自引：3，他引：50  

傅平青  刘丛强  尹祚莹  吴丰昌 《地球化学》2004,33(3):301-308

腐殖质的荧光特性被广泛用来解析其在各种天然环境中的来源及分布.由于荧光光谱分析具有灵敏度高,选择性好,且不破坏样品结构的优点,非常适合用来研究腐殖质的结构和官能团等特征.利用三维荧光激发-发射光谱研究了 Fluka腐殖酸的荧光光谱特性,结果显示,离子强度(0～0.05 mol/L KClO4)对 Fluka腐殖酸的三维荧光光谱特性影响非常小,而腐殖酸的浓度(5～100 mg/L)和溶液 pH(2～12)对其三维荧光光谱特性影响显著.当腐殖酸浓度增大时,荧光峰出现明显红移现象.荧光强度一般随着 pH的升高而增大,当 pH大于 10后呈下降趋势,我们从垃圾渗滤液溶解有机质的实验结果中也得到相同结论;在浓度为 50 mg/L和 100 mg/L的 Fluka腐殖酸中,荧光峰 B(fulvic-like)的荧光强度却在 pH=5.0左右时达到最大值,与前人报道的土壤富里酸的行为一致,质子化常数 lgK′ HL分别为 3.57和 3.13,与二羧基化合物接近,说明荧光峰 B可能与 Fluka腐殖酸结构中的羧基有关;荧光峰 A与荧光峰 B的荧光强度比值 r(A/B)在 0.61～2.59之间,并且在 pH=2～11范围内, r(A/B)与 pH具有较好的线性相关关系,表明荧光峰 A和荧光峰 B随着 pH值的改变有着相同的变化趋势.  相似文献   

粉末压片-X射线荧光光谱法分析富硒土壤样品中的硒及主次量元素   总被引：1，自引：0，他引：1  

李迎春  张磊  尚文郁 《岩矿测试》2022,(1):145-152

目前土壤中Se主要采用原子荧光光谱法测定,存在用酸量大、前处理相对复杂等缺点,对于高含量Se的测定则需要高倍稀释,无疑会扩大分析误差.本文采用粉末压片波谱-能谱复合X射线荧光光谱法测定湖北富硒土壤样品中的Se等17个主次量元素,波谱分析10个元素的同时,能谱分析As、Cu、Rb、Sr、Zr、Ba、Ni等7个元素,大幅节...  相似文献