渤海湾氮、磷营养盐在水体和沉积物中的分布特征及其相互关系

近岸海域水体和沉积物是营养盐迁移转化的重要场所。2016年8月对渤海湾水体和沉积物进行采样监测,分析了渤海湾水体和沉积物中不同形态氮、磷的含量,并研究了营养盐在水体和沉积物中的分布特征及其相互关系。结果表明:渤海湾水体中的营养盐在西部近岸地区含量较高,而在离海岸线较远的开阔海域含量较低,表现出一个明显的质量浓度梯度。说明人类活动对近岸海域水体中营养盐含量的贡献较为明显。水体中营养盐主要是以无机态为主,无机氮和无机磷分别占到总氮和总磷的76.65%和76.46%。沉积物中氮、磷营养盐表现出和水体中营养盐含量类似的空间分布特征,但形态主要以有机氮为主,无机磷的含量也仅占到30.42%。这说明夏季渤海湾水体中氮、磷营养盐主要由水中有机体通过同化作用将无机态营养盐合成为有机态营养盐进入沉积物,渤海湾西北海域的富营养化过程是水体中营养盐向沉积物迁移的一个主要驱动力。     

黄河入海口壬基酚污染分布特征

黄河口表、底层水体和沉积物中壬基酚的浓度分布特征研究结果表明,表层水体中壬基酚浓度为15.7~148.6 ng/L,平均值为47.5 ng/L;底层水体中壬基酚浓度为15.8~52.7ng/L,平均值为31.0 ng/L;表层沉积物中壬基酚浓度为2.31~5.47 ng/g,平均浓度为3.87ng/g。黄河口水体中壬基酚浓度呈现由河道向出海口外逐渐降低的趋势;河道中表层沉积物壬基酚含量高于出海口外。黄河口水体中壬基酚浓度低于文献中报道的海河口水体中的浓度,表层沉积物中壬基酚含量低于珠江口文献报道值。水体中壬基酚浓度超过抑制藤壶附着浓度(10 ng/L),河道最上游的站点水体中的浓度超过影响太平洋牡蛎幼苗的发育并增加幼苗死亡率的浓度(100 ng/L)。     

The steady-state calcium carbonate ion activity product of recent shallow water carbonate sediments in seawater: a comparison of field observations and laboratory experiments

Closed system equilibration experiments between natural seawater and shallow water calcium carbonate-rich sediments from the Bahamas yielded steady-state calcium carbonate ion activity products (CCIAP). Results obtained from initially supersaturated and undersaturated solutions were in good agreement. Experiments conducted with the addition of a biocide and/or the destruction of sediment organic matter gave results similar to those obtained in systems where these treatments were not used. Excellent agreement was also found between CCIAP values for 8 day and more than 50 day equilibration times. Our results, therefore, meet the major criteria for at least metastable equilibrium between the solution and carbonate sediment.Fine-grained samples produced a CCIAP close to the value predicted for aragonite, which is the major carbonate phase in all samples. Coarse-grained sediments produced larger CCIAP values of up to 2.8 times that predicted for aragonite equilibrium. The CCIAP for the coarse-grained sediments is probably produced by high-Mg calcite which is a significant component of these sediments. Oolite samples were among the coarse-grained sediment samples studied. They also produced results much greater than expected for aragonite equilibrium. This brings into question their use as material for measuring aragonite solubility as has been done in the past.The CCIAP measured in the laboratory experiments are in good agreement with field observations of pore-water CCIAP values from the fine-grained sediments. Coarse-grained sediments showed greater variability, with higher CCIAP values generally occurring in the pore waters than in the laboratory experiments. Since the overlying waters were always at a higher CCIAP than the pore waters, the major factor causing this difference is believed to be the short residence time of pore waters in the coarse-grained sediments, which is the result of the high-energy hydrodynamic environments in which they reside.     

The distribution and geochemistry of some trace metals in the Bermuda coastal environment

Results of the analyses of the water column and sediments of the Bermuda Platform for Cd, Cu, Fe, Mn, Ni, Pb and Zn are presented. The major process controlling the water column concentrations is physical mixing of open ocean waters with inshore waters, which are polluted by a wide range of diffuse inputs. Sedimentation within the inshore waters plays a lesser, but significant, role as do fluxes from the sediments of Fe and Mn and possibly phytoplankton uptake of Zn. Concentrations within the sediments are controlled by the formation of trace metal enriched clay/organic particles in the inshore areas and their subsequent redistribution by sediment resuspension, except for Fe and Mn which are largely associated with clay lattices.     

Vertical transport of organic materials in the northern North Pacific as determined by sediment trap experiment

Sediment traps were deployed at 5 depths of 100 through 5,250 m to collect suspended sediments in the northern North Pacific (47°51.1'N; 176°20.6'E, 5,300 m deep) in the summer of 1978. Fatty acid composition was determined in the samples of phytoplankton, particulate matter, trap sediment and bottom sediment.Fatty acid composition of the trap sediments revealed no significant vertical trend throughout the water column from depths of 100 to 5,250 m, and were also similar to those of the phytoplankton and the particulate matter from the euphotic layer. However, a marked difference in the fatty acid composition was observed between the trap sediments and the particulate matter from deep waters. Therefore, it can be concluded that the source of fatty acids in the trap sediments is the particulate matter from the euphotic layer but not from deep waters.Unsaturated fatty acids highly susceptible to biological agents were rather abundant in the trap sediments as well as in the phytoplankton and particulate matter from the euphotic layer, however no unsaturated fatty acid was found in the particulate matter from deep waters. From these findings, it is clear that the particulate matter of the euphotic layer is transported to deep waters very rapidly. As the sinking rate of fecal pellets produced by zooplankton is in the range of ten to hundreds of meters a day, fecal pellets are assumed to be the most likely carrier of rapid-transport of organic matter including fatty acids from the euphotic layer to deep waters.     

The diffusive fluxes of inorganic nitrogen across the intertidal sediment-water interface of the Changjiang Estuary in China

1IntroductionEstuaries are the main channels linking bothland and coastal seas,through which pass matterleached from land into rivers,together with anthro-pogenic matter discharged directly into the estuaries.During the past few decades,increasing concern…     

海南岛近海表层沉积物分散元素的富集特征与污染评价

对海南岛周边海域表层沉积物中7种分散元素镓(Ga)、锗(Ge)、铷(Rb)、铊(Tl)、镉(Cd)、碲(Te)和硒(Se)的分布与富集特征,及其与沉积物粒度、总有机碳和有机氮的相关性进行了较系统的分析,并分别利用内梅罗综合指数法和污染负荷指数法对这些元素的污染情况进行了初步评价。结果表明,分散元素的富集与沉积物粒度、有机碳和有机氮的含量有密切关系,除Te外,其它6种分散元素均表现出在粉砂或黏土质,以及有机碳和有机氮含量高的沉积物中趋于富集;沉积物的分散元素污染总体上呈轻微程度,但在局部海域(如海南岛西北部、西部、东南部近海海域以及陵水和三亚段海域)接近中等污染程度,说明这些区域受人类活动的影响较大,应引起海洋环境保护主管部门的重视。     

环境因子对菲在黄河口沉积物上吸附的影响

为研究多环芳烃从河口到近海的环境归趋行为与生态风险,考察了沉积物质量浓度、溶解性有机质、温度、盐度4种典型环境因子对菲在黄河口沉积物上吸附的影响,比较了黄河口与近海两种沉积物对菲的吸附性能。研究结果表明,沉积物质量浓度越低,单位质量颗粒物的菲吸附量越高;共存的溶解性有机质对菲的吸附具有增促作用,且腐殖酸比黄腐酸的作用更显著;温度的升高不利于菲的吸附,而盐度的增加有利于菲的吸附。菲在沉积物上的吸附是分配作用与表面吸附两种行为的耦合,其中黄河口沉积物以表面吸附为主,而近海沉积物以分配作用为主。近海沉积物菲吸附量显著高于黄河口沉积物菲吸附量。基于此,菲从河口到近海的迁移过程中,更易于在沉积物表面发生吸附沉降,从而可能降低水相中的生态危害,但对近海底栖生物具有潜在的健康生态风险。     

Suspended-sediment concentration and mineralogy in the central and western Mediterranean and mineralogic comparison with bottom sediment

Concentrations and mineralogy of suspensates in the central and western Mediterranean are vertically and laterally variable. This variability is related to input by resuspension of bottom sediments and from local terrigenous sources. Bottom currents flowing through constrictions at the straits of Sicily and Gibraltar and the eastern entrance of the Alboran Sea resuspend bottom sediments, giving rise to increased concentrations of suspensates in near-bottom waters and limited inputs to higher levels. There is no evidence of a suspensate-rich bottom water in the Balearic Sea.Terrigenous sources are believed to be the cause of increasing relative amounts of montmorillonite in surface waters as they flow eastward within the Mediterranean. Montmorillomite is relatively more important in suspended sediments than in bottom sediments where kaolinite—chlorite is dominant.     

柴达木盆地盐湖环境中超铀元素的分布特征

1993年采用α谱仪和大面积屏栅电离定对柴达木盆地盐湖水、地下水、河水以及地表和两个钻孔沉积物中的U,Pu和Am进行了测定。结果表明,各类水样中239Pu（含240Pu,下同）的平均含量高出表层海水约1000倍,其239Pu／238U的活度比在0．001－0．530之间;两钻孔沉积物中239Pu的平均值分别为49±0．8mBq／g和2．4±0．5mBq／g,239Pu／238U的活度比为0．141和0．088,由此探讨了U,Pu和Am的分布特征、239Pu／238U比值的变化规律以及沉积物和水中Pu的来源。     

Emanation of radon-222 from marine sediments

The behavior of radon in the sea-floor region provides a useful test of theories which describe mass transport in sediments. We have made measurements of Rn-222 and Ra-226 in near-bottom waters and near-surface sediments at the same location. The distribution of radon in sediments can be described by a simplified diagenetic equation when advection, adsorption, and bioturbation are ignored. Sediment measurements show a radon deficit relative to radium emanation. A reasonable balance is found between integrated radon deficit in sediment and radon surplus in the overlying water.In most cores radium increased with depth in the top 10 cm of sediment. This implies that bioturbation and other mixing processes do not homogenize the radium concentration in the zone of diffusive radon loss, and that radium is diffusing out of the sediments.Radon leakage is less than that predicted by previous authors. Radon leakage depends upon the physical distribution of radium in marine sediments. We present a model that predicts leakage of 30–40% for normal deep-sea sediments, in agreement with measured values.Radon surplus in near-bottom waters depends upon the radium distribution, radon leakage, and effective diffusion coefficients. These in turn depend on the properties of the sediment, such as composition, accumulation rate, and porosity. As we learn how these factors interact we may be able to infer sedimentary features from measurements of radon in overlying waters.     

Pore-water distribution and quantification of diffusive benthic fluxes of nutrients in the Huanghai and East China Seas sediments

1 Indroduction The coastal zone and continental shelf area is an important region in the global biogeochemical cycle of nutrients in the ocean. This portion of the global ocean interacts closely with the continents, atmosphere and the open ocean in a comp…     

潮流作用下洋山港水域悬沙和底沙的交换

通过对泥沙起动流速、淤积流速和不淤流速的计算,划定了悬沙和底沙交换的各个时段,提出了冲刷悬沙浓度、淤积悬沙浓度和不淤悬沙浓度的概念及其计算方法;继而导出了潮流作用下悬沙和底沙在交换层面上单位面积的日交换量计算式,并用于洋山港水域的冲淤计算。结果表明:自然状况下洋山港水域北部年淤积量为37.5 kg/m2,淤高了1.77 cm/a,属微淤;中部年冲刷量为10.0 kg/m2左右,刷深不超过0.52 cm/a,可认为冲淤平衡;南部年冲刷量为55.5 kg/m2,刷深了2.60 cm/a,属微冲。这一结果与该水域海床的自然冲淤状况相吻合。     

Processes controlling solubility of biogenic silica and pore water build-up of silicic acid in marine sediments

Dissolution experiments in batch and flow-through reactors were combined with data on sediment composition and pore water silicic acid profiles to identify processes controlling the solubility of biogenic silica and the build-up of silicic acid in marine sediments. The variability of experimentally determined biogenic silica solubilities is due, in part, to variations in specific surface area and Al content of biosiliceous materials. Preferential dissolution of delicate skeletal structures and frustules with high surface areas leads to a progressive decrease of the specific surface area. This may cause a reduction of the solubility of deposited biosiliceous debris by 10–15%, relative to fresh planktonic assemblages. Dissolution of lithogenic (detrital) minerals in sediments releases dissolved aluminum to the pore waters. This aluminum becomes structurally incorporated into deposited biogenic silica, further decreasing its solubility. Compared to Al-free biogenic silica, the solubility of diatom frustules is lowered by as much as 25% when one out of every 70 Si atoms is substituted by an Al(III) ion.The build-up of silicic acid in pore waters of sediments with variable proportions of detrital matter and biogenic silica was simulated in batch experiments using kaolinite and basalt as model detrital constituents. The steady-state silicic acid concentrations measured in the experiments decreased with increasing detrital-to-opal ratios of the mixtures. This trend is similar to the observed inverse relationship between asymptotic pore water silicic acid concentrations and detrital-to-opal ratios in Southern Ocean sediments. Flow-through reactor experiments further showed that in detrital-rich sediments, precipitation of authigenic alumino-silicates may prevent the pore waters from reaching equilibrium with the dissolving biogenic silica. This agrees with data from Southern Ocean sediments where, at sites containing more than 30 wt.% detrital material, the pore waters remain undersaturated with respect to the experimentally determined in situ solubility of biogenic silica.The results of the study show that interactions between deposited biogenic silica and detrital material cause large variations in the asymptotic silicic acid concentration of marine sediments. The production of Al(III) by the dissolution of detrital minerals affects the build-up of silicic acid by reducing the apparent silica solubility and dissolution kinetics of biosiliceous materials, and by inducing precipitation of authigenic alumino-silicate minerals.     

Microbial uncultured community of bottom sediments from the bays of Gydan and Yenisei of the Kara Sea

Using methods of molecular biology (PCR and cloning), we studied the diversity of microorganisms in the surface layers of bottom sediments from the bays of Gydan and Yenisei of the Kara Sea, which have different component composition of the pore water and mineralization level. Representatives of the domains Bacteria and Archaea were identified based on the analysis of the 16S rRNA gene fragment nucleotide sequences. The composition of the community of microorganisms in the bottom sediments changed with the changing salinity gradient of the pore waters. The phylogenetic analysis of the nucleotide sequences showed that the composition of the microbial communities in the southern parts of these bays was affected by fresh-water flows from rivers and streams from the lakes within the catchment area, whereas that in the northern parts was influenced by sea waters. The results indicate the presence of bacteria in the bottom sediments that are capable of using a wide range of substrates as a carbon source including hydrocarbons and organochlorine and aromatic compounds. These data can also indicate the presence of different pollutants in the sediments of these areas and the potential ability of bacteria to degrade chemical compounds that enter the waters and bottom sediments of the Kara Sea.     

珠江口二类水体水色三要素的优化反演

根据2003年1月份珠江口实测资料获得了适合该海域的相关参数,建立了适用于该海域的二类水体水色三要素优化反演模型,同步优化反演得到了与2003年1月25～26日实测站点相对应的2003年1月29日的SeaWiFs图像像元点的水色三要素,反演与实测水色三要素的平均相对误差分别为：叶绿素14．9％,悬浮泥沙12．1％,黄色物质13．6％。研究结果说明本研究建立的优化反演模型比较适用于珠江口二类水体水色三要素的反演,且具有较高的反演精度。     

临海工程建设对厦门北面海域底质粒级组成的影响

本文根据1980年厦门港湾底质调查的70个样品,应用R型因子分析方法,对沉积物粒级组成的成因进行分析。结果表明,该海域陆续修建的临海工程对其沉积物组成影响明显,使其由粗粒组成向细粒组成变化。尤其是高集海堤的兴建,泥沙大量淤积;海堤建成后,沉积环境日益稳定,接受沉积物以粉砂、粘土占主导地位。     

Marine barite in sediments from deep sea drilling project sites 424 and 424a (Galapagos hydrothermal mounds field)

The distribution of barite in sediments from D.S.D.P. sites 424 and 424A at the Galapagos hydrothermal mounds field is determined and the process of its formation is deduced. Barite in these deposits is associated with calcareous sediments and is completely absent from the hydrothermal material (manganese crusts and nontronite). Its concentrations tend to increase in the deeper sediments. Since manganese crusts contain significant amounts of Ba, a lack of barite in them is probably due to low concentrations of SO₄² in the sediment-seawater interface where they form. The formation of barite occurs within buried sediments, the interstitial waters of which are saturated with SO₄². The most probable source of SO₄²⁻ is the oxidation of H₂S which is released from the hydrothermal fluids percolating upwards through the sediments. Although nontronite is formed within buried sediments the environmental conditions occurring during its formation (reducing) prevent barite formation.The association of barite with calcareous sediments is due to the release of Ba by calcareous microorganisms and/or to high concentrations of Ca in the pore waters which maintain a high pH and hence SO₄²⁻ is stable.     

我国东南近岸海域表层沉积硅藻组合

对采自我国东南近岸海域18个站位78个表层沉积样品进行了硅藻鉴定分析,根据硅藻优势种和次优势种的分布特征,划分出3个组合和两个亚组合,其较好地对应分布于南海、台湾海峡和东海等3个近岸海域。统计数据表明,近岸海域表层沉积硅藻的分布受大陆入海径流的影响微乎其微,随着水深的增加,我国东南近岸海域海洋初级生产力减小,底栖种、潮间带种减少而浮游种增加;组合Ⅰ的分布表明南海东北部海域明显受黑潮流等外洋水团的影响,可应用组合Ⅱ1和组合Ⅱ2中优势种和特征种硅藻来指示水深,两亚组合面貌的差异是对冬夏两季海峡两侧受不同性质海流控制的响应;组合Ⅲ受沿岸流控制比较明显,而遭受黑潮等外洋水团的影响很弱。     

Microscopic analysis of pyrite in the sediments of two Brazilian mangrove ecosystems

This study has used scanning electron microscopy coupled with X-ray micro-analysis to compare the morphology of diagenetic pyrite formed in the sediments of two contrasting Brazilian mangroves. The Sepetiba Bay site is influenced by marine conditions, and pore waters show lower dissolved iron and higher dissolved total sulfide concentrations. The Paraíba do Sul River site, on the other hand, is influenced by fluvial waters, and shows higher dissolved iron and lower dissolved sulfide concentrations in pore waters. At both sites, pore waters were oversaturated for pyrite, and pyrite morphology was similar. The finding that pyrite morphology was similar despite marked differences in pore-water chemistry can be explained by the low solubility product of pyrite and the daily exposure of surficial sediments to air, conditioned by tidal cycles. This implies that oxygen input to the sedimentary environment is a key factor in the pyrite formation mechanism.