溶藻菌群对铜绿微囊藻的溶藻效应及其作用机理研究

水华暴发是一个世界性的问题，近年来在发展中国家显得尤其严重。水华暴发给环境和公众健康带来巨大灾难，一些蓝藻产生的毒素可以造成鱼类、鸟禽和家畜的死亡，而臭名昭著的微囊藻产生的微囊藻毒素更是有强烈致癌效应。因此，寻找控制水华藻类的有效方法非常迫切。在利用物理和化学方法处理不甚理想的情况下，利用溶藻细菌控藻成为一个新的研究方向。溶藻细菌一般直接从富营养化水体中分离，杀藻活力对有害蓝藻具有较强的选择性而不危害其它生物，尤其适合在水华发生初期使用，可以在短时间内达到阻止藻类增殖的效果。本研究富集分离到一个高效溶解铜绿微囊藻的溶藻菌群，对其溶藻效应和溶藻机制进行了探索研究。 1溶藻菌群的富集筛选及其溶微囊藻效果 富集筛选得到一个有明显抑藻效果的菌群，它对铜绿微囊藻有显著溶藻效果。与对照组相比，加入富集的溶藻菌后，第4 d开始出现溶藻现象，6~8 d出现明显的溶藻效果，8 d后测得叶绿素去除率在85%以上。 2 溶藻菌群的作用范围及溶藻特性 富集分离到的溶藻菌群对铜绿微囊藻和念珠藻有显著溶藻作用，对水华微囊藻和其它几株受试微囊藻没有明显溶藻效应。该溶藻菌群不仅可以在液体中溶解铜绿微囊藻，生长在固体平板上的藻苔也有一定的溶藻效应，生成溶藻空斑。保证快速溶藻的最大稀释度可以达到1/100, 000。 3 环境因子对菌群溶藻效力的影响 试验发现，不同的pH、温度、和光照条件下，溶藻菌群溶藻效力明显不同，且不同种类的氮源对其溶藻作用也有一定影响。这些条件对该菌群溶藻作用的影响，在相当的程度上可能取决于它们对藻和细菌两者的生长状况的影响综合。 4 溶藻菌群的溶藻作用机理 溶藻菌液过滤除菌和煮沸灭菌处理后溶藻液，未见明显的溶藻效果，只有原液具有很好的溶藻效果。因此可初步确定，蓝藻细胞的溶解可能是由溶藻菌直接接触藻细胞产生的作用效果。显微镜观察发现，细菌在溶藻的过程中频繁地接触藻细胞并侵入藻细胞，破坏进而裂解杀死藻细胞。这也进一步说明了此溶藻菌是通过直接方式杀藻。 5 溶藻菌群的菌群结构解析 分离有溶藻效果的纯菌的多次尝试都没有成功。结合DGGE和16S rDNA文库综合分析发现：Rubritepida菌，假单胞菌和鞘氨醇单胞菌是存在于铜绿微囊藻中的三种伴生细菌。加入富集的溶藻菌群后，菌群结构发生明显的变化，Rubritepida菌、假单胞菌消失，混合菌群则包含未培养黄杆菌，鞘氨醇单胞菌和噬氢菌，其中黄杆菌是优势菌群，并且细菌种群结构的变化与藻细胞消亡之间有显著的相关性。通过菌种的分离鉴定与DGGE和16S rDNA文库的测序结果比较，一些未培养菌可能在溶藻过程中起重要调控作用。 6 溶藻细菌控藻应用基础 (1) 扩大规模的模拟水华实验进一步确定了细菌对微囊藻的强烈溶解作用。 (2) 铜绿微囊藻(Microcystis aeruginosa 905, zc)、微囊藻(Microcystis spp., zd)和溶藻菌群共培养试验表明，zc可以抑制zd生长，而溶藻菌群可以溶zc。 本研究是第一次报道混合菌群的溶藻效应。该溶藻菌群对带有藻际细菌的铜绿微囊藻具有高效的溶藻效力，表明它对自然界中存在的带菌铜绿微囊藻和其它一些蓝藻的生消具有一定的控制作用。对进一步研究菌藻关系与生态学作用，以及对富营养化湖泊和水库水体中蓝藻暴发的防控，该菌群具有一定的应用潜力。 Cyanobacterial blooms break out frequently all over the world, especially in developing countries. Blooms create enormous disasters to public health and to the environment. Some cyanobacterial blooms produce extremely toxic substances that have killed fish, domestic animals and birds. It has been well known that microcystins, a hepatoxin produced by Microcystis, can promote tumors in humans. So it is very important to find an effective method for controlling the growth of the bloom-forming algae. Measures for controlling such kind of algae include physical, chemic and biologic means, but the former two may damage the aquatic environment and require high-energy inputs. The alternative approach for the elimination of nuisance algae involves the application of algicidal bacteria. The algicidal bacteria, which are nontoxic to other organisms and most of which are isolated from the eutrophic lake in situ, may be potential microbial algaecides. In the initial stages of the water blooms, they are able to restrain the biomass or multiplication of the bloom-forming algae in a short time. In order to use algicidal bacteria to suppress blooms of M. aeruginosa, we isolated a bacterial culture capable of lysing the noxious cyanobacteria M. aeruginosa. In this paper we described some properties of the bacterial culture and its growth-inhibiting or algicidal effects on the growth of M. aeruginosa, and investigated its algicidal mechanisms. 1 Enrichment of a microbial culture that lyses Microcystis aeruginosa A mixed bacterial culture was isolated from a hypereutrophic pond and showed significant algicidal activity against the noxious Microcystis aeruginosa. Algae lysis would be seen obviously 4 days later when the algae culture was killed and became yellow contrast to no-addition controls, and chlorophyll a (chl-a) reduction went beyond 85% 8 days later. 2 The host range and some other algicidal feature of the mixed algicidal culture. Microcystis aeruginosa, Nostoc sp., were susceptible to the mixed algicidal culture, while the lytic effects of this mixed culture on Microcystis flos-aquae and some other tested Microcystis were feeble.The algicidal culture can not only lyse M. aeruginosa in liquid media, but aslo lyse M. aeruginosa lawns on soft agar plates and form plaques. The maximun dilution of the mixed culture required for rapid Microcystis lysis is 1/100, 000. 3 Influences of environmental factors such as pH, temperature, illumination, and the nitrogen source on the lytic activity of the mixed bacterial culture on Microcystis aeruginosa. In our investigations, it was shown that the lytic activity of the mixed bacterial culture on Microcystis aeruginosa was straightly correlated with pH, temperature, illumination, as well as the nitrogen source in the medium. The impacts of these environmental factors on the algicidal activity of the mixed bacterial culture, to a certain extent, may depend on both the algal and the bacterial growth rates under the tested environmental conditions. 4 The mechanisms of algal cell lysis by the algicidal bacteria Death was detected when the mixed bacterial culture was added to the algal culture, but not when only the culture filtrate or autoclaved bacterial culture was added. This indicates that the mixed bacterial culture did not release extracellular products inhibitory to Microcystis aeruginosa. In addition, under the microscope, we observed frequent contacts btween bacteria and algae cells, and some bacteria can even penetrate into target algal cells and destroyed them. These results may suggest that the bacterium kill the alga by direct contact. 5 Molecular Characterization of the algicidal bacterial culture Attempts for isolation of pure bacterium or bacteria from the enrichment culture responsible for Microcystis lysis have so far been failed. Based on PCR-DGGE (denaturing gradient gel electrophoresis) and 16S rDNA clone library analysis, Rubritepida sp., Pseudomonas sp. and Sphingomonas sp., as accompanying bacteria, were existed in M. aeruginosa. The bacterial community in M. aeruginosa showed significant change after adding the enrichment culture, where uncultured Flavorbacterium sp., Sphingomonas sp. and Hydrogenophaga sp. were observed, and the uncultured Flavorbacterium sp. became a dominant species. The obvious correlation can be seen between change of bacterial population and extinction of M. aeruginosa. Compared identification of pure bacterium with sequencing of DGGE bands and the clone distribution of the clone libraries, it was inferred that some uncultured bacteria were probably play an important role in controlling the growth and abundance of M. aeruginosa. This report is the first example of a mixed bacterial culture with the ability to lyse M. aeruginosa. 6 Further study for algae control by applications of algicidal bacteria (1) Algae lysis would be seen obviously 6 days later when the algae culture was killed and became yellow contrast to no-addition controls, and chlorophyll a (chl-a) was reducted to a low level 20 days later in the simulated water bloom experiments. (2) The growth of Microcystis sp. (zd) was restrained by Microcystis aeruginosa 905 (zc) when they were co-cultured together, and zc was lysed by the algicidal bacterial culture. This report is the first example of a mixed bacterial culture with the ability to lyse M. aeruginosa, and its algicidal activity remained high against non-axenic tested M. aeruginosa, suggesting that bacteria in the natural environment could play a role in controlling the growth and abundance of M. aeruginosa and other cyanobacteria. Such bacteria could also potentially be used as agents to prevent the mass development of cyanobacteria in eutrophic lakes and reservoirs.

Controls on suppression of methane flux from a peat bog subjected to simulated acid rain sulfate deposition

The effect of acid rain SO42− deposition on peatland CH4 emissions was examined by manipulating SO42− inputs to a pristine raised peat bog in northern Scotland. Weekly pulses of dissolved Na2SO4 were applied to the bog over two years in doses of 25, 50, and 100 kg S ha−1 yr−1, reflecting the range of pollutant S deposition loads experienced in acid rain-impacted regions of the world. CH4 fluxes were measured at regular intervals using a static chamber/gas chromatographic flame ionization detector method. Total emissions of CH4 were reduced by between 21 and 42% relative to controls, although no significant differences were observed between treatments. Estimated total annual fluxes during the second year of the experiment were 16.6 g m−2 from the controls and (in order of increasing SO42− dose size) 10.7, 13.2, and 9.8 g m−2 from the three SO42− treatments, respectively. The relative extent of CH4 flux suppression varied with changes in both peat temperature and peat water table with the largest suppression during cool periods and episodes of falling water table. Our findings suggest that low doses of SO42− at deposition rates commonly experienced in areas impacted by acid rain, may significantly affect CH4 emissions from wetlands in affected areas. We propose that SO42− from acid rain can stimulate sulfate-reducing bacteria into a population capable of outcompeting methanogens for substrates. We further propose that this microbially mediated interaction may have a significant current and future effect on the contribution of northern peatlands to the global methane budget.

Surface pigments,algal biomass profiles,and potential production of the euphotic layer:Relationships reinvestigated in view of remote-sensing applications

Maps of surface chlorophyllous pigment (Chl a + Pheo a) are currently produced from ocean color sensors. Transforming such maps into maps of primary production can be reliably done only by using light-production models in conjuction with additional information about the column-integrated pigment content and its vertical distribution. As a preliminary effort in this direction. $\ticksim 4,000$ vertical profiles pigment (Chl a + Pheo a) determined only in oceanic Case 1 waters have been statistically analyzed. They were scaled according to dimensionless depths (actual depth divided by the depth of the euphotic layer, $Z_e$) and expressed as dimensionless concentrations (actual concentration divided by the mean concentration within the euphotic layer). The depth $Z_e$ generally unknown, was computed with a previously develop bio-optical model. Highly sifnificant relationships were found allowing $\langle C \rangle_tot$, the pigment content of the euphotic layer, to be inferred from the surface concentration, $\bar C_pd$, observed within the layer of one penetration depth. According to their $\bar C_pd$ values (ranging from $0.01 to > 10 mg m^-3$), we categorized the profiles into seven trophic situations and computed a mean vertical profile for each. Between a quasi-uniform profile in eutrophic waters and a profile with a strong deep maximum in oligotrophic waters, the shape evolves rather regularly. The wellmixed cold waters, essentially in the Antarctic zone, have been separately examined. On average, their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values of $ρ$, the ratio of Chl a tp (Chl a + Pheo a), have also been obtained for each trophic category. The energy stored by photosynthesizing algae, once normalized with respect to the integrated chlorophyll biomass $\langle C \rangle _tot $ is proportional to the available photosythetic energy at the surface via a parameter $ψ∗$ which is the cross-section for photosynthesis per unit of areal chlorophyll. By tanking advantage of the relative stability of $ψ∗.$ we can compute primary production from ocean color data acquired from space. For such a computation, inputs are the irradiance field at the ocean surface, the "surface" pigment from which $\langle C \rangle _tot$ can be derived, the mean $ρ value pertinent to the trophic situation as depicted by the $\bar C_pd or $\langle C \rangle _tot$ values, and the cross-section $ψ∗$. Instead of a contant $ψ∗.$ value, the mean profiles can be used; they allow the climatological field of the $ψ∗.$ parameter to be adjusted through the parallel use of a spectral light-production model.

A Global Crisis for Seagrass Ecosystems

Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions. They also serve as “coastal canaries,” global biological sentinels of increasing anthropogenic influences in coastal ecosystems, with large-scale losses reported worldwide. Multiple stressors, including sediment and nutrient runoff, physical disturbance, invasive species, disease, commercial fishing practices, aquaculture, overgrazing, algal blooms, and global warming, cause seagrass declines at scales of square meters to hundreds of square kilometers. Reported seagrass losses have led to increased awareness of the need for seagrass protection, monitoring, management, and restoration. However, seagrass science, which has rapidly grown, is disconnected from public awareness of seagrasses, which has lagged behind awareness of other coastal ecosystems. There is a critical need for a targeted global conservation effort that includes a reduction of watershed nutrient and sediment inputs to seagrass habitats and a targeted educational program informing regulators and the public of the value of seagrass meadows.

On-line voltammetric monitoring of dissolved Cu and Ni in the Gulf of Cadiz, south-west Spain

Geochemical processes in estuarine and coastal waters often occur on temporally and spatially small scales, resulting in variability of metal speciation and dissolved concentrations. Thus, surveys, which are aimed to improve our understanding of metal behaviour in such systems, benefit from high-resolution, interactive sampling campaigns. The present paper discusses a high-resolution approach to coastal monitoring, with the application of an automated voltammetric metal analyser for on-line measurements of dissolved trace metals in the Gulf of Cadiz, south-west Spain. This coastal sea receives metal-rich inputs from a metalliferous mining area, mainly via the Huelva estuary. On-line measurements of dissolved Cu, Zn, Ni and Co were carried out on-board ship during an eight-day sampling campaign in the study area in June 1997. A pumping system operated continuously underway and provided sampled water from a depth of ca. 4 m. Total dissolved metal concentrations measured on-line in the Gulf of Cadiz ranged between <5 nM Cu (<3 nM Ni) ca. 50 km off-shore and 60–90 nM Cu (5–13 nM Ni) in the vicinity of the Huelva estuary. The survey revealed steep gradients and strong tidal variability in the dissolved metal plume extending from the Huelva estuary into the Gulf of Cadiz. Further on-line measurements were carried out with the automatic metal monitor from the bank of the Odiel estuary over a full tidal cycle, at dissolved metal concentrations in the μM range. The application confirmed the suitability of the automated metal monitor for coastal sampling, and demonstrated its adaptability to a wide range of environmental conditions in the dynamic waters of estuaries and coastal seas. The near-real time acquisition of dissolved metal concentrations at high resolution enabled an interactive sampling campaign and therefore the close investigation of tidal variability in the development of the Huelva estuary metal plume.

Natural 13C abundance as a tracer for studies of soil organic matter dynamics

A method for measuring the long- and medium-term turnover of soil organic matter is described. Its principle is based on the variations of 13C natural isotope abundance induced by the repeated cultivations of a plant with a high 13C/12C ratio (C4 photosynthetic pathway) on a soil which has never carried any such plant. The 13C/12C ratio in soil organic matter being about equal to the 13C/12C ratio of plant materials from which it is derived, changing the 13C content of the organic inputs to the soil (by altering vegetation from C3 type into C4 type) is equivalent to a true labelling in situ of the organic matter. Two cases of continuous corn cultivation (Zea mays: δ13C = −12%.) on soils whose initial organic matter average δ13C is −26%. were studied. The quantity of organic carbon originating from corn (that is the quantity which had turned-over since the beginning of continuous cultivation) was estimated using the 13C natural abundance data. After 13 yr, 22% of total organic carbon had turned-over, in the system studied. Particle size fractions coarser than 50μm on the one hand, and finer than 2μm on the other. contained the youngest organic matters. The turnover rate of silt-sized fractions was slower

黄土区不同地类坡面水沙动态过程及其发生机理的模拟实验研究

利用模拟降雨在降雨性质上的可控性优势,分析了在黄土丘陵区具有代表性的几种坡面土地利用方式(林灌地、封禁荒草地、弃耕农地)的产流产沙动态过程及发生机制。结果表明,在降雨条件相近时,不同类型坡面状况的初始产流时间差异明显。次降雨过程中各地类小区产沙和产流动态变化不完全一致,产沙量较产流量增加趋势更为显著。在降雨和土壤条件相对一致的条件下,不同地类小区的侵蚀产沙过程差异显著,其中林地和草灌地与坡耕农地相比可增加入渗,减水效益明显,减沙效益更为显著,表明实施林草植被建设,包括退耕封禁等措施在内的生态治理减蚀效益明显,能够有效地减少坡面的来水来沙;并提出了可反映土壤抗蚀能力的量化指标——单位冲刷强度,为在实验流域对包括退耕还林草、封禁措施在内的生态恢复重建过程的流域水沙变化及其效应评估提供量化指标。

Model analysis of dissolved inorganic phosphorus exports from the Yangtze river to the estuary

In this paper, we estimate the inputs of phosphorus (P) to the Yangtze River Basin and exports of dissolved inorganic phosphorus (DIP) from the river to the estuary for the period 1970-2003, by using the global NEWS-DIP model. Modeled DIP yields range from 2.5 kg P km(-2) yr(-1) in 1970 to 4.6 kg P km(-2) yr(-1) in 1985, and then dramatically increase to 14.1 kg P km(-2) yr(-1) in 2003. No significant difference between the modeled and measured values at the level of P = 0.05 is observed. The study also demonstrates variable source contributions of P to the modeled DIP during the period 1970-2003. Point sewage P input accounted for approximately 100% in the period 1970-1985 and substantially decreased to 24.8% in 2003. Chemical fertilizer contributed 25.4% of DIP yields in 1986 and increased continuously to 50.3% in 2003, while a stable trend in manure P contribution averaging 22.9% of DIP yields was shown in the same period. The study concludes that P inputs to the Yangtze River Basin and the river DIP export to the estuary have substantially increased during the study period consequence to human pressure.

Response of coastal marine eco-environment to river fluxes into the sea: A case study of the Huanghe (Yellow) River mouth and adjacent waters

The impact of the Huanghe (Yellow) River outflows on its estuary was investigated with river gauging and shipboard hydrographic observations. The river flux has been decreasing dramatically; the discharges of water and sediment in the 1990s dropped to 27.4% and 31.9% of those in the 1950s, respectively, resulting in frequent and lengthy events of downstream channel dry-up since the 1970s. There were accumulatively 897 zero-flow days during the 1990s in the river course below the Lijin Hydrological Station, 100 km upstream from the river mouth, which is 82.4% of that in 1972. As freshwater input decreases, river-borne nutrients to the estuarine increased significantly. Concentration of dissolved inorganic nitrogen (DIN) in the 1990s was four times of that in 1950s. Changes in amount and content of the riverine inputs have greatly affected the estuarine ecosystem. Over the past several decades, sea surface temperature and salinity in the estuary and its adjacent waters increased and their distribution pattern altered in response to the reduction of freshwater inflow. The distribution of and seasonal succession in nutrient concentrations in the surface layer have also changed with a shift of river outlet and the decrease in riverine nutrient loads. Furthermore, deterioration of estuarine ecosystem by less river input has decreased primary productivity in the deltaic region waters, and in turn depressed the fishery. (C) 2008 Published by Elsevier Ltd.

Distribution and mobility of metals in agricultural soils near a copper smelter in South China

The distribution and mobility of heavy metals in the paddy soils surrounding a copper smelting plant in south China was investigated. We assessed the degree of metal contamination using an index of geoaccumulation. The metals were divided into two groups: (1) Cu, Zn, Pb and Cd, whose concentrations were heavily affected by anthropogenic inputs, and (2) Ni, Co and Cr, which were mainly of geochemical origin. Concentrations of Cu, Cd, Zn, and Pb in the polluted soils were higher than the Chinese soil quality criteria. The chemical partitioning patterns of Pb, Zn and Cu indicated that Pb was largely associated with the residual and NH2OH HCl extractable fractions. In contrast, Cd was predominantly associated with the MgCl2 extractable fraction. A large proportion of Cu was bound to the acidic H2O2 extractable fractions, while Zn was predominantly found in the residual phase. The fraction of mobile species, which potentially is the most harmful to the environment, was found to be elevated compared to unpolluted soils in which heavy metals are more strongly bound to the matrix. The mobility of the metals was studied by water extraction using a modification of Tessier's procedure, and the order of mobility was Zn > Cd > Cu > Ce > Pb.

Numerical simulation of principal tidal constituents in the South China Sea, Gulf of Tonkin and Gulf of Thailand

The principal tidal constituents M-2, S-2, K-1 and O-1 in the South China Sea, Gulf of Tonkin and Gulf of Thailand are simulated simultaneously using the numerical scheme of Kwok et al. (1995 Proceedings of the 1st Asian Computational Fluid Dynamics Conference, pp. 16-19). The average differences between the computed and observed harmonic constants are mostly within 5 cm and 10 degrees for amplitudes and phase-lags, respectively. The simulated tidal regimes in the present model are believed to be more accurate than the previous numerical results. Our studies confirm that a clockwise rotating M-2 amphidromic system lies in the southeast of the Gulf of Thailand and an S-2 amphidromic system at the near-shore area of the northeast South China Sea. The linear tidal energy equation developed by Garrett (1975 Deep-Sea Research 22, 23-35) is generalized to the nonlinear case. Based on the numerical results, the energy budgets in the South China Sea and its subareas, namely the Taiwan Strait, the Gulf of Tonkin, the Gulf of Thailand and the remaining area are investigated. The tidal motion in the Taiwan Strait is maintained mainly by the energy fluxes from the East China Sea for both semidiurnal and diurnal species and partially from the Luzon Strait for semidiurnal species. For the other parts of the South China Sea, the tidal motion is mainly maintained by the energy fluxes through the Luzon Strait. The energy inputs from the tide-generating force are negative for semidiurnal species and positive for diurnal species. (C) 1999 Elsevier Science Ltd. All rights reserved.

胶州湾及其邻近海域的浮游植物－种类组成与数量变化

研究胶州湾浮游植物的物种组成与时空分布的特点，对于了解该湾生态系统的现状与历史变化趋势以及生态系统对自然条件变化和人类干扰的响应具有重要意义。 本文根据2004年每月一次采集的浮游植物样品，分析了胶州湾浮游植物的物种组成和优势种的时空分布情况。调查发现浮游植物共142种，分属于6门53属，其中硅藻门40属113种，占总物种数的79.6%；甲藻门10属24种，占总物种数的16.9%；其它为金藻门1属2种，裸藻1属1种，绿藻1属2种。浮游植物丰度周年波动范围为11.12－14602.39×104cells/m3，全年平均为1857.55×104cells/m3。全年丰度最高的藻为环纹劳德藻(Lauderia annulata)，出现在2月份，而全年的丰度最高值也出现在2月份。在胶州湾中，硅藻所占比例最大，平均为97.44%，最高为99.95%，最低为82.55%。浮游植物的丰度的周年变化：有两个高峰，分别出现在2月份和10月份，是典型的温带海域双高峰的分布形式。 胶州湾浮游植物的优势种分析，采用Kikvidze等（2002）提出的确定优势种数量的计算方法，再依据各物种的优势度排序最终确定优势种。其中在多样性最低的6月和10月，优势种数目均为1种，分别为丹麦细柱藻（Leptocylindrus danicus）和中肋骨条藻（Skeletonema costatum）。而在多样性指数较低的1月、2月，优势种数目分别为2和3；而在物种多样性比较高的5月、7月、11月，由于分布相对比较分散，所以优势种数量较多。这说明这个方法可以较好地完成对胶州湾浮游植物群落分析时确定优势种的目标。优势种出现频率较多的种类为中肋骨条藻（1、3、4、5、8、10、11、12月）、洛氏角毛藻(Chaetoceros lorenzianus)（7、8、9、11、12月）、尖刺拟菱形藻(Pseudonitzschia pungens)（2、3、5、7月）、加拉星杆藻(Asteronella kariana)（1、2、3、5月）、密联角毛藻(Chaetoceros densus)（5、11、12月）、扭鞘藻(Streptothece thamesis)（7、8、9月）、夜光藻(Noctiluca scintillancs)（4、5、7月）、奇异菱形藻(Nitzschia paradoxa)（5、11、12月）,对这些种的时空分布进行了分析。 对2004年胶州湾的浮游植物数据进行分层聚类分析后，发现可以将胶州湾划分为三个海区：湾南与湾外海区、湾中西部海区、湾东海区。

长江口上升流区营养盐动力学

近年来，东中国海赤潮灾情严重，且74.7%的赤潮集中在 30°30′～32°00′N、122°15′～123°10′E的“赤潮高发区”。在研究该区赤潮成因时，长江口沿岸上升流的影响越来越受到人们的关注，并被一些专家观测和研究。但目前为止，针对该区营养盐动力学特征及其对叶绿素a影响的研究较少，且不系统。 本文根据2004年四个季度月的调查资料，系统地探讨了长江口上升流区营养盐动力学特征；估算了上升流的营养盐通量，并和陆源输入通量进行了比较。初步探讨了上升流对该区营养盐结构和浮游植物生长的影响。为深入研究长江口富营养化和赤潮形成机制提供了参考。 结果表明春季在122°20′～123°00′E，31°00′～32°00′N以北海域存在低温、高盐、低溶解氧的沿岸上升流。它不但可把底层高含量磷酸盐输送到10m层以上海区，而且还为上层海区输入了相对低含量硝酸盐和硅酸盐，从而改善了上层营养盐结构，使得营养盐比值接近Redfield Ratios，同时还改善了上层的透明度；从而有利于浮游植物的繁殖。夏季上升流受到强大的长江冲淡水压制，表现不如春季明显，主体水团出现在122°20′～123°00′E，31°15′～31°50′N海区10m层以下。 在秋、冬季，上升流现象被更强的对流现象所掩盖，表现为台湾暖流表层水的入侵。表、底层水域不仅温、盐度分布十分接近，而且营养盐结构差异也较小。冬季台湾暖流水中的磷酸盐含量远比秋季高，与春、夏季上升流水团中磷酸盐含量接近。硝酸盐和硅酸盐含量比秋季稍高，比春、夏季上升流水团中的含量稍低。 叶绿素a季节性分布表明，在春、夏季的10m层以下水域，叶绿素a受到透明度限制，含量相差不大；而在表层和10m层之间，春季叶绿素a的含量远高于夏季，说明春季的营养盐结构和自然条件更有利于浮游植物的繁荣生长。在秋季台湾暖流水影响的区域，表层叶绿素a含量较夏季稍低。而冬季该区叶绿素a含量则是最低的。 对长江口上升流水团春季营养盐通量的计算结果表明，上升流水团中磷酸盐输送通量远远高于长江径流输入，是其径流通量的两倍以上，可能会成为影响该海区磷酸盐分布以及浮游植物生长的一个值得关注的因素。 关键词：上升流，营养盐动力学，营养盐结构，叶绿素a，长江冲淡水

The nitrogen isotopic composition of dissolved nitrate in the Yangtze River (Changjiang) estuary, China

The nitrogen isotopic composition of dissolved nitrate (delta N-15-NO3-) in surface water of the Yangtze River estuary was determined in four seasons of 2006. delta N-15-NO3- ranged from 0.4 parts per thousand to 6.5 parts per thousand and varied with seasons and geographic regions, reflecting the dynamics of nitrogen cycling in the estuarine ecosystem. delta N-15-NO3- was markedly lower in February than in other seasons and exhibited conservative mixing, which was probably attributed to the NO3- being sourced from the atmospheric deposition and agricultural fertilizer. In the upper estuary, the influence of riverine inputs was important during all surveys. in the turbidity maximum zone, nitrification was found with nitrate depleted in N-15 in May, whereas denitrification resulting in heavy delta N-15-NO3- played an important role in August. More enriched delta N-15-NO3- values coinciding with losses of nitrate concentrations based on the conservative mixing model were found in the adjacent marine area in May, and may reflect obvious phytoplankton assimilation of dissolved nitrate. In this manner, delta N-15-NO3- may be a sensitive indicator of nitrogen sources and biogeochemical processing existing in this estuary in conjunction with the variations of dissolved nitrate and other environmental factors. (C) 2009 Elsevier Ltd. All rights reserved.

Organochlorine micropollutants in the Jiulong River Estuary and Western Xiamen Sea, China

Organochlorine contaminants including 12 polychlorinated biphenyl (PCB) congeners and 18 insecticides were determined in water, pore water and sediments of the Jiulong River Estuary and Western Xiamen Sea, China. The results showed that the levels of the total PCBs ranged from non-detectable to 1500 ngl(-1) in water, from 209 to 3870 ngl(-1) in pore water, and from 2.78 to 14.8 ng g(-1) dry weight in sediments. Total organochlorine insecticide concentrations were from below the limit of detection to 2480 ngl(-1) in water, from 267 to 33400 ngl(-1) in pore water, and from 4.22 to 46.3 ng g(-1) dry weight in sediments. Concentrations of PCBs and insecticides in pore water were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. The PCB congeners with the highest concentrations were CB153, CB180 and CB194, which together accounted for 68-87% of total PCBs in water, pore water and sediment. Among the hexachlorocyclohexane (HCH) compounds, beta-HCH was found to be a major isomer. Analysis of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane (DDT) and its metabolites showed that 1, 1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group. In comparison to a 1998 study in the Western Xiamen Sea, levels of organochlorines were enhanced due probably to recent inputs and changes in sediments. (c) 2004 Elsevier Ltd. All rights reserved.