气相色谱-质谱法测定水产加工制品中酚类抗氧化剂残留

本文建立了一种固相萃取-气相色谱-质谱检测法,用于检测水产加工制品中5种酚类抗氧化剂残留。5种酚类抗氧化剂为二丁基羟基甲苯(BHT)、丁基羟基茴香醚(BHA)、特丁基对苯二酚(TBHQ)、4-己基间苯二酚(4-HR)和没食子酸丙酯(PG)。研究过程如下:用乙酸乙酯提取样品,硅胶柱净化,正己烷、乙酸乙酯洗脱,气相色谱-质谱测定,外标法定量。研究显示:在质量浓度为0.05~10μg/mL范围内,抗氧化剂的响应值与质量浓度的线性关系良好,相关系数为0.997 1~0.999 8。在0.05~1mg/kg添加浓度下,丁香鱼干、虾干和干贝加标样品的日内和日间平均回收率为70.6%~119%,相对标准偏差为1.09%~9.80%;BHT、BHA、TBHQ和4-HR的检出限为0.01mg/kg,最低定量限为0.05mg/kg;PG的检出限为0.05mg/kg,最低定量限为0.25mg/kg。研究结果表明,本文建立的固相萃取-气相色谱-质谱检测法可以有效的检测出水产加工制品中的5种酚类抗氧化剂残留。     

莱州湾海域水体中有机氯农药和多氯联苯的浓度水平和分布特征

以固相萃取/气相色谱法测定了莱州湾海域水体中22种有机氯农药和多氯联苯类化合物的浓度水平和分布特征。结果表明,莱州湾海域表层水体中有机氯农药浓度范围为N.D.~32.7ng/L,底层水中的浓度范围为N.D.~11.7ng/L。在该海域水体中共检出有机氯农药3种,β-666是水体中主要的有机氯农药污染物。多氯联苯类在底层水样中检出2种,总浓度范围在4.5~27.7ng/L之间。该海域有机氯农药和多氯联苯的分布特征是近岸高,离岸低,由近岸向湾外延伸方向依次递减。并对莱州湾表层水中总有机氯农药与海水盐度、氯度、溶解氧和pH间的关系作了初步探讨,得出总有机氯农药与盐度、氯度间有一定的相关关系,相关系数均为0.59。方法测定5种有机氯农药化合物的空白加标回收率为97.3%~126.0%,相对标准偏差为2.8%~8.6%;测定5种多氯联苯类化合物的空白加标回收率为88.6%~151.8%,相对标准偏差为6.7%~10.4%。     

高效液相色谱法测定食品中嘌呤含量

为测定食品中嘌呤含量,建立了食品中多组分嘌呤含量测定的反相离子对高效液相色谱(RP-IP-HPLC)分析方法,对几种主要食品中的腺嘌呤、鸟嘌呤、黄嘌呤、次黄嘌呤含量进行测定。结果表明,采用Agilent XDB-C18色谱柱,水-甲醇-冰乙酸-10%四丁基氢氧化铵(V/V/V/V,879/100/15/6)为流动相,检测波长为254nm,流速为1mL/min时4种嘌呤可完全分离。测得4种嘌呤物质的回收率在91.8%~108.7%之间,方法的相对标准偏差(RSD)为2.7%~6.5%。不同种类食品中嘌呤总含量由高到低依次为:动物肝脏、动物肌肉、果蔬、菌类和蛋类。     

过氧化氢-茜素红s体系催化动力学分光光度法测量痕量钴(Ⅱ)

本文利用催化动力学原理,建立了新的测定痕量钴(Ⅱ)的分析方法。研究体系为:钴(Ⅱ)-茜素红s-过氧化氢-碳酸钠。所得的最佳反应条件为:pH=11.00,反应时间t=7.50min,反应温度θ=35.0℃,ρ(C_(14)H_7O_7SNa·H_2O)=6.400×10~(-2) g·L~(-1),Φ(H_2O_2)=7.200×10-2%。在该反应条件下,此分析方法的相对标准偏差为1.85%~2.96%,检出限为4.21×10~(-2)ng/mL。在淡水体系中相对标准偏差在1.93%~2.79%之间,而加标回收率在98.7%~101.3%之间。相较于其他测量方法,本文所建立的分析方法具有操作简单,分析温度低,准确度高,检出限低,分析时间短等优点。     

RP-HPLC法同时测定翅碱蓬中四种黄酮化合物的含量

建立RP-HPLC(反相高效液相色谱法)同时测定翅碱蓬中四种黄酮化合物-芸香苷、槲皮素3-β-D-葡萄糖苷、水仙苷和槲皮素的含量。采用Kromasil C18色谱柱(4.6 mm×250 mm,5μm),检测波长为361nm,柱温为30℃,流动相为甲醇-0.4%冰乙酸(55︰45),流速1.0mL/min,四种黄酮类化合物得到很好的分离。芸香苷、槲皮素3-β-D-葡萄糖苷、水仙苷和槲皮素浓度均为0.001~0.01 mg/mL范围内呈现良好线性关系,相关系数R2在0.9990~0.9996,加标回收率(n=3)范围为82.39%~99.03%。该方法简单、快速、高效,可以用于翅碱蓬中四种黄酮化合物的含量分析。     

高效液相色谱法测定海水中溶解态游离氨基酸

采用邻苯二甲醛柱前衍生-高效液相色谱-荧光检测器(OPA—HPLC-FLD)联用技术分离测定了海水中的14种主要溶解游离氨基酸(DFAA),通过邻苯二甲醛—3-巯基丙酸(OPA—3-MPA)柱前衍生后,在XDB-C18柱上分离。不同氨基酸测定的精密度(RSD)为1.62%~3.80%,检测限为11.4~69.7 ng.L-1,海水加标回收率在92%~110%之间。利用该方法测得青岛近海表层海水中氨基酸浓度为0.015~0.284μmolL-1。     

ICP-MS测定聚碳酸酯塑料中锑及其不确定度评定

采用微波消解-电感耦合等离子体质谱法(ICP-MS)测定聚碳酸酯塑料中锑含量。考察了消解介质、消解样品量的选择对消解结果的影响,优化选择了电感藕合等离子体-质谱法(ICP-MS)的测定参数。在选定的最佳消解和测定条件下,称取0.200 0g聚碳酸酯塑料样品于5mL HNO3试剂下消解,实验相对标准偏差RSD为3.68%,对实验样品添加5.00ng/mL标准进行加标回收实验,加标回收率在95.1%~110.9%之间,检出限为0.022ng/mL。该方法具有准确、简便、快速等优点,可以满足聚碳酸酯触塑料材料中锑的检测要求。通过建立不确定性评定数学模型,分析了影响不确定度的主要来源,对样品质量、体积定容、仪器测量重复性、标准储备液、曲线拟合等影响不确定度的分量进行分析,最后计算出合成标准不确定度和扩展不确定度。ICP-MS法测试塑料中锑含量可以表示为(0.568±0.057)mg/kg,可使实验结果更具客观性和准确性。     

ICP-AES测定海洋生物体中13种元素的微波消解条件优化

报道了微波密闭消解正交试验条件优化电感耦合等离子体发射光谱法(ICP-AES),同时测定8种海洋生物体中硒、铁、锰、锌、钙、镁、锶、砷、镉、铬、铜、铅和镍等13种元素含量的实验结果。优化后的样品消解条件为加入的HNO3V:H O2 2V=6.0 mL:1.0 mL,第二步程序升温温度为170℃,消解时间20 min;测定标准曲线相关系数大于0.999,相对标准偏差为0.30%~2.55%,加标回收率为92.0%~104.8%,方法检出限为0.0010~0.0468μg/g。结果表明,优化后方法测定操作简便、具有高的灵敏度、准确度和精密度,且能多元素同时测定,适合于海洋生物样品中这些元素含量的准确测定,并可为评估海产品食用安全提供科学依据。     

海水中丙烯酸的高效液相色谱法建立及应用

建立了一种测定海水介质中丙烯酸的高效液相色谱法。采用耐纯水相和较低pH的Agilent SB-Aq-C18柱(100 mm×4.6 mm i.d.,5 μm), 0.35%磷酸溶液(pH=2)为流动相,使用紫外检测器,检测波长为210 nm,外标法定量测定。丙烯酸的保留时间在14.2~ 14.9 min,方法的检出限为4 nmol/dm3(S/N=3),在0.01~10 μmol/dm3的范围内均有良好的线性关系,相关系数可达0.999 6,加标回收率为95.4%~98.1%,相对标准偏差为1.3%~1.6%(1.04~2.32 μmol/dm3)。采用0.2 μm滤膜重力过滤冷藏的办法来保存海水丙烯酸样品。检测出2011年5月份青岛近海海水中丙烯酸的平均浓度为(0.101±0.069) μmol/dm3;海洋微藻球形棕囊藻在整个生长周期内培养体系中丙烯酸的浓度为0.339~2.219 μmol/dm3。     

海水中硫丹及衍生物气相色谱快速测定及应用

通过固相微萃取(SPME)技术富集海水中6种硫丹及其衍生物,使用气相色谱-电子捕获检测器(GC-μECD)测定和外标法定量,建立海水中硫丹及其衍生物的快速测定方法。结果表明:硫丹及其衍生物的线性范围为2.5～100.0μg/L,相关系数为0.990～0.998,检出限为0.10～21.30 ng/L。在3个加标条件(5,10和25μg/L)下,人工海水硫丹的加标回收率为85.60%～119.50%,相对标准偏差(n=6)为1.3%～7.8%。实际海水硫丹的加标回收率为90.60%～120.70%,相对标准偏差为1.6%～7.9%。该方法应用于青岛近岸海域海水的测试,在青岛近岸水体中未检出α-硫丹和β-硫丹,检出硫丹衍生物:硫丹醚(N.D.～1.758μg/L),硫丹内酯(1.040～11.260μg/L)和硫丹硫酸酯(1.009～6.091μg/L)。实际应用表明该方法前处理简便易行、灵敏度高,并可满足海水中硫丹及其衍生物的快速检测分析。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.