广东吴川近岸海域表层海水重金属含量及生态风险分析

为了解广东吴川近岸海域重金属含量现状及其潜在风险，以便有针对性地对重金属污染进行防控，于2020年10月采集了吴川海域41个站位的表层海水样，运用综合指数法、HAKANSON潜在生态风险指数法和相关性分析法评价了其重金属污染程度和潜在生态风险。结果表明：Cu含量范围为0.48～14.1μg/L，平均含量为1.75μg/L;Pb含量范围为0.07～7.79μg/L，平均含量为0.44μg/L;Zn含量范围为3.98～65.8μg/L，平均含量为9.22μg/L;Cd含量范围为0.03～0.17μg/L，平均含量为0.05μg/L;Cr含量范围为0.62～2.69μg/L，平均含量为1.92μg/L;Hg含量范围为0～0.039μg/L，平均含量为0.021μg/L;As含量范围为0.39～1.42μg/L，平均含量为0.93μg/L。吴川海域各重金属元素平均含量均未超过中国海水水质一类标准。通过与国内外其他海域表层重金属含量的比较，吴川海域表层海水重金属含量整体处于中低水平。按其相关性可将吴川海域重金属元素分为3类：第1类为Cu-Pb-Zn-Cd组合，第2类为Cr-As组合，第3类为Hg...     

胶州湾水域重金属铬的分布及迁移

根据1979年的胶州湾水域调查资料，分析了重金属铬在胶州湾水域的分布、迁移和季节变化。研究结果表明；春季，胶州湾水城铬污染较轻，大部分海域水质状况较好，而到夏季没有受到污染。在时空分布上，春季，铬污染形成了明显的梯度，由东北向西南方向递减，从112．3μg／L降低到0．2μg／L。夏季，铬的水平分布比较均匀，表层水体铬的含量较低，范围在0．10～1．40μg／L之间波动。因此认为，1979年整个胶州湾水域的重金属铬属于面污染源。而且，当铬进入胶州湾海域后，很快吸附在水体中的悬浮颗粒上，并被水流较快地带离胶州湾水城，几乎没有在胶州湾水域表、底层留下污染痕迹。     

基于GIS的海水环境监测站位优化——以胶州湾为例

文章利用2003-2012年5月、8月和10月胶州湾19项海水监测要素归一化后数据,基于ArcGIS软件地学统计模块,通过Kriging插值模型对归一化数据进行检验分析及站位优化。结果表明,优化后的31个监测站位估计误差标准差梯度较优化前大幅降低,平均估计误差标准差由0.160降低到0.147,降低了8.3%。站位优化后不仅可对胶州湾沿岸重点污染源以及胶州湾海域总体海水质量实施有效监控,并且可以作为今后胶州湾海水监测的常规站位。优化后的监测网在满足监测精度需要的同时,能够较大程度节省监测网的运行费用,可以为其他海域海水监测站位优化及海洋主管部门提供技术支撑,具有重要的应用价值。     

胶州湾海水中无机氮的分布与富营养化研究

根据2003年112月胶州湾海区12个航次海水无机氮等的调查资料,分析了该海域生态环境中无机氮的分布特征及时空变化,评价了水质的富营养化状况。结果表明,测区全年溶解无机氮的平均含量为17.70μmol／dm^3。在4个季节中,溶解无机氮以NO3-N的含量为最大,占58．2％,是氮主要存在形态,其中秋季含量最高,占溶解无机氮的64．74％。无机氮分布从东北部高含量区域向湾内及湾口方向呈逐步递减趋势。溶解无机磷的年平均含量为0．49μmol／dm^3,表层海水4个季节中N／P比平均为39．41,胶州湾海水中的磷相对于氮是匮乏的。据营养状态指数划分,胶州湾的东、北岸海域属富营养化区,夏、秋两季可能受到赤潮的严重威胁。     

胶州湾海水中溶解氨基酸的研究

于１９８６年１月－１１月用高效液相色谱法分析胶州湾１０个站位表层和底层海水中溶解游离氨基酸（ＤＦＡＡ）的组成、含量的分布及其季节变化。结果表明，７个站位的表层海水中月平均总溶解游离氨基酸（ＴＤＦＡＡ）含量范围为１．２４－２．２８ｕｍｏｌ／Ｌ。多数站位在２月份处于最低值（０．４ｕｍｏｌ／Ｌ），１１月份达最高值（５．０ｕｍｏｌ／Ｌ）。所测氨基酸中，Ｇｌｕ，Ｇｌｙ、Ａｒｇ、Ｌｅｕ，Ｏｒｎ，Ｓｅｒ等占优势     

渤海湾北部海域表层海水的表观铜络合容量

为给渤海湾北部海域重金属铜环境容量研究提供科学依据，采用阳极溶出伏安法对该海域12个站位表层海水样品的表观铜络合容量(ACuCC)和条件稳定常数(K)以及络合容量指数(CCI)进行了测定和计钟：。得到该海区表层海水的表观铜络合容量在228．0～673．4nmol／L之间，平均值为437．5nmol／L，条件稳定常数对数值(IgK)变化范围在7．41～8．84之间，平均值为7．89，络合容量指数在72．69％～92、92％之间，平均值为82．93％。表明该海域表层海水对重金属铜具有较强的络合能力。     

惠州海水重金属污染特征及生态风险评估

重金属是主要的环境污染物之一。文章对惠州近岸海域19个站位的表层海水重金属含量进行分析,利用算术均值型多因子指数法和Hakanson指数法进行重金属污染和生态风险评价。结果显示:(1)2015年8月,惠州海水Cu、Zn、Cr、Cd、Hg、As等6种重金属元素平均值分别为4.85μg/L、4.85μg/L、0.595μg/L、0.263μg/L、0.045μg/L、2.85μg/L,符合海水水质第一类标准,Pb含量平均值为8.46μg/L,符合第三类海水水质标准。(2)算术均值型多因子指数(I=0.379)说明,惠州海水重金属污染级别为尚清洁。(3)相关分析显示,海水中Zn、Hg具有同样的来源,pH对海水Pb分布有重要影响。(4)潜在生态危害系数Eir值由大到小依次为Hg、Pb、Cu、Cd、As、Zn、Cr,综合潜在生态危害指数(RI=22.6)表明惠州海水重金属具有轻微生态危害。     

胶州湾水域有机农药六六六分布及迁移

根据1979年的胶州湾水域调查资料，分析有机农药六六六（HCH）在胶州湾水域的分布、迁移和季节变化。分析结果表明，在一年中，胶州湾水域夏季HCH的污染严重，而春、秋季污染较轻。在时空分布上，春、夏、秋季整个胶州湾水域的HCH水平分布比较均匀，属于面污染源。HCH的表、底层含量都相近，水体的垂直分布均匀。整个胶州湾水域，春季HCH含量增加，夏季迭到高峰5．393～12．480μg／L，秋季降低到低值0．073～0．685μg／L，这与胶州湾的入湾河流的流量变化相一致。因此认为，农药HCH的使用导致胶州湾水域HCH含量的变化。     

胶州湾水域有机农药HCH的分布及水质标准

根据1986年4、7和10月的胶州湾水域调查资料,通过对有机农药HCH在胶州湾水域的分布、来源和季节变化的分析,研究结果表明：HCH含量在整个胶州湾水域都非常低,在这1 a中都〈0.100μg/L,在胶州湾水域HCH含量都优于国家一类海水水质标准,水质在HCH含量方面更加清洁;水体中HCH的表层含量已经没有季节变化,这...     

南海中部海域铵浓度及其与浮游植物的关系

本文根据１９８３年９月至１９８５年１月南海中部海域调查的资料，分析了该海区海水中铵浓度的频率分布，垂直分布特征和次表层铵最大值的形成及其与环境因子的关系。结果表明，铵浓度变化范围在０－２．７１μｍｏｌ／ｄｍ＾３之间，铵含量小于０．５μｍｏｌ／ｄｍ＾３的样品数约为样品总数的７８％，铵最大值出现在表层和次表层机率较大。文中还对该海域表层的铵含量与浮游植物的关系进行了初步探讨。     

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.