生物降解甲壳质的研究

介绍了利用生物 (主要是微生物 )降解甲壳质的一些研究进展 ,着重讨论了在甲壳质降解中起重要作用的几丁质酶的基本性质和分子生物学特征。指出了生物处理海洋资源 ,开发有用活性物质的应用前景。     

酶法制备几丁寡糖和壳糖研究现状与进展

对用酶法制备几丁寡糖和壳寡糖研究现状与进展进行了综述。几丁质酶、壳聚糖酶、溶菌酶和 N-乙酰葡萄糖胺酶等专一性的水解酶及糖酶、蛋白酶、脂肪酶等水解酶对几丁质和壳聚糖都具有部分或完全非专一性水解作用。介绍了这些酶类的作用机理及相关微生物的种类和作用条件     

珠江口磨刀门枯季表层沉积物特征

根据2003年12月在珠江口磨刀门附近水域采集的河口表层沉积物粒度分析资料,研究了磨刀门河口表层沉积物的组成、分布、运动等特征及其动力环境指示作用。研究表明,磨刀门口枯季表层沉积物组成以粉砂为主,其次为粘土和砂。表层沉积物平均中值粒径为6．356Ф(0．0122mm),表层沉积物的级配与悬沙的级配较接近。口门附近表层沉积物的中值粒径、分选性沿程没有明显的变化。枯季表层沉积物的形成以悬移质沉积为主,跃移和推移运动形式很少。磨刀门由于受人类活动的影响枯季表层沉积物与历史相比出现明显的细化,磨刀门口附近枯季表层沉积物的特征在一定程度上反映了枯季以潮流作用为主的相对较弱的动力环境。     

Fatty acids in recent sediments in the St. Lawrence estuary

Surface sediments along the Rimouski section in the St. Lawrence estuary were sampled at the surface and at 10 cm depth. Fatty acids were extracted and analysed. Saturated and unsaturated fatty acid contents at the two depths vary with the nature of the sediments. The clay sediments rich in organic matter contain more fatty acids than the corresponding sand or gravel. Unsaturated fatty acids were more abundant in the surface sediments. Some iso- and anteiso-odd carbon fatty acids were detected in the sediments; these acids could indicate a microbial activity. Correlation is made with the fatty acid contents of the water column together with the surface microlayer of the estuarine water.     

长江口外沉积物中多环芳烃结构类型的分布

本文采用色谱—质谱—质谱—计算机系统技术,分析了长江口外两个表层沉积物中多环芳烃组分,并探讨了其有机质的来源和地球化学特征。     

福建省漳江口表层沉积物中滴滴涕的残留特征

采用GC-ECD方法分析了漳江口表层沉积物样品中滴滴涕（DDTs）的残留量,并对其来源和生态风险进行了分析与评价。结果表明,沉积物中DDTs的残留量平均为16.4 ng·g^-1,其4种异构体p,p′-DDE,p,p′-DDD,o,p′-DDT,p,p′-DDT的平均残留量分别是4.12ng·g^-1,9.54 ng·g^-1,0.529 ng·g^-1和2.26 ng·g^-1。DDTs沿漳江呈波浪型分布,至佳洲岛分流前DDTs的残留比较高。组成特征显示DDTs主要为环境中的早期残留,且多为厌氧性生物降解,而在Z9站（江心岛后）近期可能有新的DDTs输入。与其它地区相比,漳江口表层沉积物中的DDTs残留属于中等水平。生态风险评价结果显示,86.7%的样品DDTs含量超过风险评估低值（ERL）,13.3%样品的含量超过风险评估中值（ERM）,说明存在较高的生态风险,对生态环境已造成一定的危害,必须引起重视。     

长江口外表层沉积物黏土矿物分布特征（英文）

依据对长江口外表层沉积物187个站位沉积物样品的黏土矿物含量分析,研究了长江口外表层沉积物黏土矿物的组合特征和分布规律。长江口外表层沉积物伊利石为优势矿物,平均含量为60.3%;次之为蒙脱石,平均为14.9%;高龄石平均含量13.5%,绿泥石平均含量为12.3%。黏土矿物的组合类型以伊利石-蒙脱石-高岭石-绿泥石型为主,伊利石-高岭石-绿泥石-蒙脱石型次之;长江口外表层沉积物黏土矿物主要为陆源成因,物质主要来源于黄河和长江的供给。Q型聚类分析显示,现代黄河物质及老黄河物质主要沉积于研究区东北部北纬29°30′以北地区,长江物质主要在研究区西部及中部区域沉积。     

Geochemical signature as paleoenvironmental markers in Holocene sediments of the Tinto River estuary (Southwestern Spain)

High absolute concentrations of metals associated to sulfide deposits located at the river source (Fe, Cu, Zn, Pb, Cd, and As) have been determined from the study of major and trace element concentrations in sediment samples obtained in two vibracores in the Tinto River estuary. In most cases, the enrichment factor (EF) for these metals is over 2. Cu, Zn and As have much higher EF, over 10 in surficial samples. Fe oxy-hydroxide precipitation in high-chlorinity zones and its scavenging effect on metals is the main control process on the chemical composition of sediment. Vertical evolution of the sedimentary and geochemical characteristics of the cores show that the estuary has undergone a process of progressive shallowness and a relative increase in acidic river water volume with respect to seawater. This effect has originated a downstream displacement of acid mixing processes affecting the estuary, which is reflected in higher metal concentrations in sediments of the outer zones of the system.     

河口潮滩沉积物磷的季节性累积和生物有效性

对长江口潮滩表层沉积生磷的赋存形态和含量的研究表明,碎屑态磷为沉积物中磷的主要形态,约占总磷的62.52%;铁结合态磷和有机磷次之,分别占总磷的18.06%和14.69%;自生磷灰石加钙结合态磷和吸附态磷最少。综合研究区内的各种理化条件,指出弱吸附态磷、铁结合态磷和有机磷是长江口潮滩潜在生物可利用磷,约占总磷的33.16%,是导致水体富营养化的潜在因素。上覆水的盐度效应是影响沉积物铁结合态磷含量的关键性因子;而自生磷灰石加钙结合态磷的含量变化则与上覆水的温度、溶氧量及沉积物有机质的分解有关;有机磷在时间和空间尺度上都存在较大变化,主要与潮滩生物动态过程,即磷的再矿化有关。     

闽江河口表层沉积物重矿物特征与物源示踪

对闽江河口近岸海域的230个表层沉积物样品和闽江20个表层沉积物样品进行重矿物分析,系统地研究了重矿物的分布特征及其物源指示。研究区共鉴定出重矿物27种,主要以普通角闪石、绿帘石、磁铁矿和黑云母为主。根据重矿物组合分布特征,将研究区分为两个矿物组合区,并划分为3个矿物组合亚区。闽江口近岸沉积区(Ⅰ-1区)矿物组合为普通角闪石-磁铁矿-绿帘石,受闽江物质影响很大;近岸混合沉积区(Ⅰ-2区)矿物组合为普通角闪石-磁铁矿-黑云母-绿帘石,受浙闽沿岸流携带物质和闽江物质共同影响沉积形成,闽江物质影响明显减弱;残留沉积区(Ⅱ区)矿物组合为普通角闪石-绿帘石-磁铁矿,主要为受后期改造的晚更新世海侵边界层。     

甲壳质生产物料平衡分析及清洁生产途径

简要介绍了甲壳质传统酸碱法、酸碱法和微生物法清洁生产工艺及其优缺点以及主要物料投入和流失物,分析了以废弃虾、蟹壳为原料,以酸碱法作试剂生产甲壳质的污染状况;通过对酸碱法清洁生产工艺与传统生产工艺的比较,提出了酸碱法生产中使甲壳质废水排放达标的若干对策,指出了甲壳质清洁生产的可行途径;同时展望了微生物法清洁生产甲壳质的前景。     

长江口细颗粒泥沙絮凝作用及其制约因素研究

简要介绍了人海河口细颗粒泥沙的絮凝机理;以长江口细颗粒泥沙絮凝作用的研究为例,概述了影响河口细颗粒泥沙絮凝的若干因子;着重介绍了长江口水体生物地球化学过程对于细颗粒泥沙絮凝作用影响的研究进展。在此基础上,结合国内外相关研究的最新进展以及河口工程与环境中的泥沙问题,提出未来工作设想。     

长江口和黄东海沉积物单矿物分选的常用方法和流程

沉积物碎屑矿物组分既受物源控制,又受水动力影响,单矿物分选应首先选取适当的粒级,细砂粒级经常采用,但不是固定在这一粒级; 控制重液密度是重液分选的关键环节,不同目标矿物,可通过调配不同的比重液进行分离分选,并可使用离心重液法提高分选效能; 磁选是分选不同磁性特征矿物的简单便捷方法,钕铁硼强磁铁的使用,可部分代替电磁分选仪的功能,对样品量少、矿物种类多、磁性变化大地矿物组合可起到重要的分组作用; 化学分选采用不同浓度的各种溶剂在不同条件下处理试样,有选择性地溶掉妨碍矿物,留下目标矿物; 手工分选单矿物重点在于剔除其他方法难以分离的杂质,保障样品的纯度和代表性; 角闪石和石英分选流程,代表着单矿物分选的基本技术路线,不同方法合理的前后衔接,使单矿物分选高效、快捷、准确,但还有一些矿物分选难题尚未解决,需要深入研究和实践。     

Distribution and sources of organic carbon, nitrogen and their isotopes in sediments of the subtropical Pearl River estuary and adjacent shelf, Southern China

The isotopic composition (δ¹³C and δ¹⁵N) and organic carbon (OC) and total nitrogen (TN, organic plus inorganic) content of 37 carbonate-free surficial sediments of the subtropical Pearl River estuary and the adjacent shelf of South China Sea (SCS) was determined. The δ¹³C values indicate that the sediment organic material is a mixture from two sources, terrestrial and marine. Several of the sediments have extremely low (< 4) OC / TN ratios, which could be due to low OC contents and/or to a significant fraction of the TN present as inorganic nitrogen adsorbed on clays. In general, the spatial patterns of OC, TN, δ¹³C and δ¹⁵N are similar. Values are low at the river mouth and on the western coast, suggesting proportionally greater accumulation of terrestrial particulate organic matter relative to marine phytodetritus, which is limited by low productivity in the turbid plume of the Pearl River. Algal-derived organic carbon (al-OC) content is estimated to be low (≤ 0.06%) at the river mouth and higher (up to 0.57%) on the adjacent inner shelf based on a mixing model of end members.     

The effects of semi-lunar spring and neap tidal change on nitrification, denitrification and N2O vertical distribution in the intertidal sediments of the Yangtze estuary, China

To explore the influences of semi-lunar spring and neap tidal changes on nitrogen cycling in intertidal sediments, a comparative study among waterlogged, desiccated and reflooded systems was carried out in August 2005 and February 2006 by analyzing nitrification, denitrification and N₂O depth profiles in the intertidal flats of the Yangtze estuary. Laboratory experiments showed that alternating emersion and inundation resulted in the significant changes in nitrification and denitrification rates in the intertidal sediment systems. Due to the desiccation-related effects, lowest nitrification and denitrification rates were observed in the desiccated sediment cores. Highest nitrification and denitrification rates were however detected in the waterlogged and reflooded systems, respectively. It is hypothesized that the highest nitrification rates in the waterlogged sediments were mainly attributed to higher nitrifier numbers and NH₄⁺ being more available, whereas the availability of NO₃⁻ might dominate denitrification in the reflooded sediments. In addition, the highest N₂O concentrations were detected in the reflooded sediment cores, and the lowest found in the dried sediment cores. It was also shown that N₂O in the intertidal sediments was mainly from nitrification under the desiccated condition. In contrast, N₂O in the intertidal sediments was produced mainly via denitrification under the waterlogged and reflooded conditions. It is therefore concluded that the semi-lunar tidal cycle has a significant influence on nitrification, denitrification and N₂O production in the intertidal sediment systems.     

Rare earth elements in suspended and bottom sediments of the Mandovi estuary, central west coast of India: Influence of mining

Rare earth elements (REEs) in the suspended particulate matter (SPM) of the Mandovi estuary indicated that the mean total-REEs (∑REE) and light REE to heavy REE ratios are lower than that of the average suspended sediment in World Rivers and Post-Archean average Australian shale. High ∑REE were associated with high SPM/low salinity and also with high SPM/high salinity. Although the ∑REE broadly agree with SPM levels at each station, their seasonal distributions along transect are different. SPM increased seaward in the estuary both during the monsoon and pre-monsoon, but consistently low at all stations during the post-monsoon. The mean ∑REE decreased marginally seaward and was <25% at sea-end station than at river-end station. Spatial variations in ∑REE are maximum (64%) during the pre-monsoon. Strong to moderate correlation of ∑REE with Al, Fe and Mn in all seasons indicates adsorption and co-precipitation of REEs with aluminosilicate phases and Fe, Mn-oxyhydroxides. The ratio of mean ∑REE in sediment/SPM is low during the monsoon (1.27), followed by pre-monsoon (1.5) and post-monsoon (1.62). The middle REE- and heavy REE-enriched patterns with positive Ce and Eu anomalies are characteristic at every station and season, both in SPM and sediment. They also exhibit tetrad effect with distinct third and fourth tetrads. Fe-Mn ore dust is the most dominant source for REEs. However, the seasonal changes in the supply of detrital silicates, Fe-Mn ore dust and particulates resuspended from bottom sediments diluted the overall effect of salinity on fractionation and distribution of REEs in the estuary.     

The characteristics of the nematode faunas in subtidal sediments of a large microtidal estuary and nearshore coastal waters differ markedly

The present study examines traditional paradigms regarding the differences between faunas in estuaries vs coastal waters. The ecological characteristics of the free-living nematode faunas of nearshore, subtidal sediments in downstream and upstream areas of the large, microtidal Swan River Estuary are compared with those similarly recorded seasonally in subtidal sediments along an adjacent part of the coast of temperate south-western Australia. Overall, the nematode species richness recorded in the upstream (38) and downstream estuarine areas (58) and from throughout the estuary (61) were substantially less than in marine waters (75). In addition, the value for Simpson’s diversity index was marginally less in the estuary and the dominance of the most abundant species greater. In contrast, the mean nematode species richness and diversity in individual cores followed the reverse trend, reflecting a combination of less variability among the species compositions and far greater densities in the cores from estuarine sediments. Furthermore, the mean density (numbers 10 cm⁻²) was far higher in both upstream (341) and downstream (903) areas of the estuary than in marine waters (87). Although the compositions of the assemblages in upstream and downstream estuarine areas differed markedly from each other at the species, genus and family levels, these differences were less pronounced than those between either of these areas and marine waters. The trophic compositions at the moderately sheltered and fully exposed marine sites differed from that in both areas of the estuary, whereas that at the most sheltered marine site was similar to that in the downstream estuarine area, with both containing substantial proportions of epistrate-grazing species. The variations among the species richness, diversity, densities and taxonomic and trophic compositions of nematode assemblages in the sediments of the two estuarine areas and nearby marine waters appear to reflect differences in 1) salinity regimes, 2) extents of exposure to wave action and its related effects and 3) amounts and types of food available to nematodes.     

Phosphorus speciation and availability in intertidal sediments of a temperate estuary: relation to eutrophication and annual P-fluxes

For a better understanding of the phosphorus dynamics and bioavailability in temperate climates, sequential chemical extraction techniques were used to study sediment P-pools distribution and relative importance in a eutrophicated estuary.Results indicate a shift in importance from the iron-bound P fraction to the CaCO₃-bound P fraction with increasing salinity, which suggests a decrease in bioavailable P from the most inner part of the estuary seaward, as the CaCO₃ associated P is believed to be less available for organisms. Salt marsh plants also influence sediment P speciation, through higher organic P fractions (mainly humic acid associated P) when compared to non-vegetated sediments. The ratio of iron-bound P to iron-oxyhydroxides may be used as an indicator of P availability, since it reflects the number of available P sorption sites in the metal oxides. This ratio was lowest in the intermediate zone of the estuary (13.7) when compared to the outer site (29.6) and the upper site (26.1), suggesting saturation of sorption sites. Co-incident with this, the intermediate site is characterized by the occurrence of macroalgal blooms during summer. In the present case, superficial sediments in the Mondego estuary do not show a clear seasonal trend, either in total amounts of exchangeable P or P speciation. Pools of exchangeable P in the surface sediment were 30 times higher than the annual net-export of P (14 ton year⁻¹) from the estuary. The annual P release from the sediment appears diminutive in comparison with the pool-size. Management measures to reduce nutrient input into coastal water systems should therefore consider that phosphorus availability may persist as a result of sediment supply, even after reducing the external point sources.