The role of benthic macrophytes and their associated macroinvertebrate community in coastal lagoon resistance to eutrophication

Eutrophication is widely recognised as one of the major menaces to coastal environments, particularly enclosed bays and lagoons. Although there is a general understanding of the consequences of eutrophication in these systems, there is a lack of sufficient knowledge concerning biotic feedbacks that influence eutrophication patterns and the resistance capacity of coastal environments.In this paper, the isotope ratios of main producers and consumers of a Mediterranean lagoon were examined in order to elucidate the fate of anthropogenic inputs from the main watercourse flowing into the lagoon.The results of the study of stable isotope data in the Mar Menor lagoon reflected that the whole benthic community plays an important role as a natural ‘filter’ that removes excess nutrients from the water column and stores them in the sediments, thereby enhancing lagoon resistance to eutrophication.     

Sediment-preserved diatom assemblages can distinguish a petroleum activity signal separately from the nutrient signal of the Mississippi River in coastal Louisiana

We analyzed the preserved diatom assemblages in dated sediment cores collected from five locations in the Louisiana Bight to test if there was a signature of petroleum extraction activities (hopanes and barium) distinct from the well-documented effects of nutrient loading. The results of a multi-dimensional scaling analysis indicate that the diatom assemblage changes documented throughout the 40 year record could be explained by three variables: barium and hopanes concentrations, and Mississippi River nitrogen loading. The results of a canonical correspondence analysis demonstrated that these signals could be distinguished through correlations with specific diatom species. The abundance of Actinoptychus senarius, for example, was negatively correlated with barium and the Pseudo-nitzschia delicatissima complex was positively correlated with nitrogen loading. These results provide a “proof-of-concept” demonstration that diatom assemblages preserved in the sediments can be used to study the effects of petroleum extraction activities, and that these ‘petroleum signals’ may be distinguished from other significant influences such as nutrient loading.     

Increasing eutrophication in the coastal seas of China from 1970 to 2050

We analyzed the potential for eutrophication in major seas around China: the Bohai Gulf, Yellow Sea and South China Sea. We model the riverine inputs of nitrogen (N), phosphorus (P) and silica (Si) to coastal seas from 1970 to 2050. Between 1970 and 2000 dissolved N and P inputs to the three seas increased by a factor of 2–5. In contrast, inputs of particulate N and P and dissolved Si, decreased due to damming of rivers. Between 2000 and 2050, the total N and P inputs increase further by 30–200%. Sewage is the dominant source of dissolved N and P in the Bohai Gulf, while agriculture is the primary source in the other seas. In the future, the ratios of Si to N and P decrease, which increases the risk of harmful algal blooms. Sewage treatment may reduce this risk in the Bohai Gulf, and agricultural management in the other seas.     

Spatiotemporal variability of hypoxia and eutrophication in Manila Bay,Philippines during the northeast and southwest monsoons

Hypoxia in Manila Bay, Philippines was previously reported during the northeast monsoon (dry season) in February 2010. In this study, four more field surveys of the same 31 stations were conducted in July 2010, August 2011 and 2012 (wet season, southwest monsoon), and February 2011 (dry season, northeast monsoon). During the wet season, bottom hypoxia spread northward towards the coast with dissolved oxygen (DO) ranging from 0.12 to 9.22 mg/L and the bay-wide average reaching 2.10 mg/L. Nutrient levels were elevated, especially near the bottom where dissolved inorganic nitrogen reached 22.3 μM (July 2010) and phosphorus reached 5.61 μM (August 2011). High nutrient concentrations often coincided with low near-bottom DO content. Our work builds on the preliminary assessment of hypoxia in Manila Bay, the importance of repeated temporal studies, and shows hypoxia to prevail significantly during the southwest monsoon (wet season) when increased freshwater discharge caused strong water column stratification.     

The optical and molecular signatures of DOM under the eutrophication status in a shallow,semi-enclosed coastal bay in southeast China

We applied stable carbon isotopes, ultraviolet-visible absorption(UV-Vis), fluorescence excitation-emission matrices spectroscopy(EEMs), and Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS) to investigate the chemical composition and sources of the dissolved organic matter(DOM) in both the water column and pore water in Xiangshan Bay, a representative semi-enclosed and eutrophic bay in Zhejiang Province, China. One protein-like fluorescent component(C1) and two humic-like fluorescent components(C2 and C3) were identified by PARAFAC modeling. The concentration of dissolved organic carbon(DOC), the relative intensities of C2, C3, and black carbon-like compounds are all negatively correlated with salinity, indicating that there is a dilution effect of terrestrial signals by seawater in Xiangshan Bay. The differences in light penetration ability of Xiangshan Bay cause different degrees of photo-degradation, which may play an important role in the transformation of organic matter in Xiangshan Bay. The weak correlation between the C1 fluorescent component and salinity indicates that autochthonous sources cannot dominate the protein-like FDOM in the Xiangshan Bay drainage area. Multiple sources(such as anthropogenic inputs and release of pore water) also affect the distribution of the protein-like fluorescent component under eutrophication conditions. The relative proportion of the protein-like fluorescent component in Xiangshan Bay is on a medium level in China and anthropogenic inputs may be a significant source of DOM in coastal bays.     

Chlorophyll a and its derivatives in sediments of the Odra estuary as a measure of its eutrophication

Chlorophyll a and its selected derivatives, as well as chlorophylls b and c have been determined in samples of recent (0-10 cm) sediments, collected at 30 stations in the Szczecin Lagoon, Pomeranian Bay and the Bornholm Deep. Samples were retrieved in different seasons between 1992 and 2001, including the time before and after the great flood of July 1997. Regarding the content of chlorophyll a and its derivatives in sediments, the Szczecin Lagoon may be classified as permanently eutrophic and the Pomeranian Bay and Bornholm Deep as mesotrophic. A lack of correlation between chlorophylls b, c and chlorophyll a indicated that intensive blooms of cyanobacteria occur in the Szczecin Lagoon, which is a characteristic of eutrophic zones. The chlorin a results are related to selected parameters characterizing the aquatic environment. The values for nutrients, salinity and temperature in near-bottom waters, as well as granulometry and organic carbon in the sediments verify the above conclusions.     

The conditional probability of earthquake occurrence and the next large earthquake in Tokyo, Japan

The use of probability distribution ofrecurrence times as described by theexponential, Weibull and Rayleihgprobability densities form the core of theprobabilistic seismic prediction analysispresented in this paper. Using these threeprobabilistic models we derive threeformulas to calculate the conditionalprobability P(t|t) than an earthquakeevent will occur in the time interval (t, t+ t), provide that it has not occurredin the elapsed time t since the last largeearthquake (M 6.4) in the Tokyo area.This paper proposes a new method toestimate the time interval t foroccurrence of a new large earthquake inTokyo area. This time interval is measuredafter the elapsed time (t) since the lastlarge earthquake. To do this we use thethree formulas for the conditionalprobability P(t|t) and the criterionof the maximum conditional probability ofearthquake occurrence.Using a list of historical earthquakeswhich have occurred in the Tokyo area asgiven by Usami (1976, pp. 235–243), wefound that: (1) Using the exponentialmodel, it is estimated that a highlydamaging earthquake magnitude M 6.4, mayoccur before the year 2009.50, orequivalently before June 2009; (2) Usingthe Weibull model, it is estimated that thedamaging earthquake (M 6.4) may occurbefore the year 2129.80, or equivalentlybefore October 2129.     

Organic and inorganic occurrence of selenium in Laerma Se-Au deposit

Se and other trace elements in kerogen are determined. Based on biochemical evidence, theoretical calculations and infrared spectra, it is indicated that Se may occur as organic minerals by combining with organic legends. The inorganic occurrence of selenium is also discussed. Project supported by the National Natural Science Foundation of China (Grant No. 60633110).     

Dynamics of mesozooplankton assemblages in subtropical coastal waters of Hong Kong: A comparative study between a eutrophic estuarine and a mesotrophic coastal site

A monthly comparative study of mesozooplankton biomass and composition between a eutrophic Pearl River estuarine site (WE) and a mesotrophic coastal-oceanic site (EO) in Hong Kong waters was conducted to examine the response of mesozooplankton to nutrient-rich riverine discharge. Although the annual average mesozooplankton biomass was higher at WE than at EO, they were not statistically significant. Variations of mesozooplankton biomass at both stations followed similar trends of Chl a concentrations, with the exception of July at WE where mesozooplankton biomass was low but total Chl a was high. This mismatch may be due to the high flushing effect of the Pearl River discharge in summer and a time lag in mesozooplankton population growth. On the other hand, the composition of mesozooplankton was significantly modified by riverine discharge and eutrophication conditions. While small copepods dominated at both sites, the eutrophic estuarine water had a high abundance of barnacle and polychaete larvae, while cladocerans, bivalve larvae, gastropod larvae and chaetognaths mainly occurred at EO. Eutrophication increased the top-down role of copepods in the grazing community, revealed by an increase in the percentage of copepods in the total metazoan mesozooplankton, especially during the period of high river discharge. Moreover, mesozooplankton diversity at the two stations was similar, and they both showed relatively higher diversity during autumn and winter and lower diversity during summer, especially at WE. These results suggest that, despite high nutrient and Chl a concentrations in estuarine waters, mesozooplankton biomass were not enhanced compared to coastal waters with no river impact, possibly due to poor food quality and increased predation in the eutrophic estuarine waters.     

云南水汞在连发地震前短临异常及震后变化特征

通过对1995年5月6日—1996年2月3日发生在云南境内及其中缅边境一带的4组5次M≥6．0级强震的研究,发现水汞在强震连发期都出现短临异常及震后变化;与2001年云南省内6组7次5．0—5．9级中强地震短临异常及震后变化进行比较,结果表明强震连发期水汞的短临异常特征表现为异常台站多、异常幅度大、异常范围广和多台站水汞在异常中发震。中强震连发期水汞的短临异常特征与此相反。表现为异常台站少、异常幅度小、异常范围小和多台站水汞在异常结束后发震。     

基于小波神经网络耦合模型对云南星云湖富营养化气象驱动因子的分析

气象因子是影响湖泊富营养化的重要因素,而湖泊富营养化对人群健康、生态系统和社会经济等均有负面影响.本文基于统计资料及遥感数据,结合Morlet小波分析和BP多层前馈神经网络(BP神经网络)构建了不同时间尺度下的小波神经网络耦合模型,分析了19862011年云南星云湖水华强度变化与月降雨量、月平均气温、月平均风速、月日照...     

火山区台站观测的地震波分析与应用

以长白山天池台记录的地震Ｐ、Ｓ波及腾冲台记录的地脉动资料为基础，分析研究了火山区台站观测的地震波在微震监测与分析、火山地震类型判别、火山区介质非均匀性与各向异性分析以及地震预报与火山喷发监测在预报中的应用．     

Fluvial to bay sequence stratigraphy and seismic facies of the Cretaceous to Paleogene successions in the MITI Sanriku‐oki well and the vicinities,the Sanriku‐oki forearc basin,northeast Japan

This paper describes the significant depositional setting information derived from well and seismic survey data for the Upper Cretaceous to Lower Eocene forearc basin sediments in the central part of the Sanriku‐oki basin, which is regarded as a key area for elucidating the plate tectonic history of the Northeast Japan Arc. According to the results of well facies analysis utilizing cores, well logs and borehole images, the major depositional environments were of braided and meandering fluvial environments with sporadically intercalated marine incursion beds. Seismic facies, reflection terminations and isopach information provide the actual spatial distributions of fluvial channel zones flowing in a north–south trending direction. The transgression and regression cycles indicate that the Upper Cretaceous to Lower Eocene successions can be divided into thirteen depositional sequences (Sequences SrCr‐0 to SrCr‐5, and SrPg‐1 to SrPg‐7). These depositional sequences demonstrate three types of stacking patterns: Types A to C, each of which shows a succession mainly comprising a meandering fluvial system, a braided fluvial system with minor meandering aspects in the upper part, and major marine incursion beds in the middle part, respectively, although all show an overall transgressive to regressive succession. The Type C marine incursion beds characteristically comprise bay center and tidal‐dominated bay margin facies. Basin‐transecting long seismic sections demonstrate a roll up structure on the trench slope break (TSB) side of the basin. These facts suggest that during the Cretaceous to Eocene periods, the studied fluvial‐dominated forearc basin was sheltered by the uplifted TSB. The selective occurrences of the Type C sequences suggest that when a longer‐scale transgression occurred, especially in Santonian and early Campanian periods, a large bay basin was developed, creating accommodation space, which induced the deposition of the Cretaceous Kuji Group along the arc‐side basin margin.     

太湖渔业资源现状(2009-2010年)及与水体富营养化关系浅析

根据2009-2010年的太湖鱼类资源调查,结合历年渔业资料和水环境监测数据,分析太湖渔业资源的发展趋势和结构特征.结果表明:本次调查共采集到鱼类47种,隶属10目14科37属,原常见鱼类种类数明显减少,鲤科等定居性鱼类成为主体;同时,太湖渔业产量近年来增长迅速,渔获物中湖鲚等小型鱼类比重增加,渔业资源的单一化和小型化趋势加剧.根据湖泊水体环境特征的空间差异,对太湖东部湖区、北部湖区和湖心区3个不同类型湖区间的渔业资源特征进行比较.其中在北部湖区和湖心区,浮游食性的湖鲚成为绝对优势种,2008年其产量分别占湖区总产量的70.7％和80.4％,其他主要鱼类所占比重仅为0.2％ -3.0％;而东部湖区草食性和肉食性鱼类的比例较高,鱼类结构相对合理,不同湖区间渔获物的组成差别反映出湖区鱼类组成与环境特征相适应的特点.针对太湖渔业资源与水体富营养化关系进行探讨,提出需加强渔业与湖泊环境功能之间关系的研究,重视水生植被在太湖渔业可持续发展中作用的建议.     

Transport and dispersion of particulate Hg associated with a river plume in coastal Northern Adriatic environments

The role of suspended particulate matter (SPM) as an important carrier of mercury (Hg) dispersed into the Gulf of Trieste and in the adjacent Grado lagoon (Northern Adriatic Sea) was studied during a high Isonzo River inflow and the resulting river plume formation. Despite the fact that extreme flood events are rare during the year, they account for most of the PHg influx (37-112 ngL(-1)) into the Gulf of Trieste. When the river plume is diverted to the SW under the influence of an E-NE wind, the tidal flux acts as a "transport belt" carrying the PHg, mostly inorganic, into the Grado lagoon. A preliminary estimation indicates that the amount of PHg entrapped in the lagoon basin following a tidal semi-cycle accounts for 1.4 kg/12h, which corresponds to about 49% of the total Hg carried by the tidal flow. These findings should be considered in future remediation strategies in the lagoon environment.     

Daily availability of nutrients and metals in a eutrophic meso-tidal coastal lagoon (Óbidos lagoon, Portugal)

This baseline reports daily variations of physico-chemical parameters, nutrients and metals in water of two sites [eutrophic conditions (BB) versus reference (LL)] in Óbidos coastal lagoon (Portugal). Dissolved oxygen in BB varied between 40% saturation levels (night) and 190% (daylight). , and ratios to Al of Mn, Fe and Pb in suspended particulate matter increased during the period of lower oxygenation, indicating exportation of nutrients and metals from the sediment to water at night. At LL, O₂ values oscillated always around 100%. and Mn/Al ratio at LL were always lower than at BB and no increases were found during the night. The input of and Mn provided from the sediment at BB during the night could surpass the contribution of freshwater discharges. PCA confirmed the separation of most samples from BB and LL. These results pointed to the importance of assessing chemical conditions over day-night cycles.     

综合营养状态指数(TLI)在夏季长江中下游湖库评价中的局限及改进意见

综合营养状态指数(TLI)在中国湖库富营养化评价中应用非常广泛.对于该指数的各分项指标,基于叶绿素a的评估结果是富营养化风险的直接体现,是最终指示;而基于理化指标(总氮、总磷、透明度和高锰酸盐指数)的评估结果是间接指示.如果两者TLI评估结果存在显著差异,则说明基于理化参数的TLI评估结果低估或者高估了实际富营养化水平和相关风险.本文针对长江中下游湖库的基于水质理化指标和基于叶绿素a的TLI结果是否匹配的问题开展了调查分析.结果表明,对于非通江浅水湖泊而言,基于总氮、总磷、高锰酸盐指数的TLI评估结果均低估了富营养化水平和相关风险;对于通江浅水湖泊而言,基于总氮、总磷和透明度的TLI评估结果高估了富营养化水平和相关风险,而基于高锰酸盐指数的结果低估了富营养化水平;对于深水水库,基于总氮的TLI指数评估结果高估了富营养化水平,而基于总磷、透明度和高锰酸盐指数的结果低估了富营养化水平.上述水质理化指标和叶绿素a评估结果不匹配的原因为以下两点:第一,部分物理化学指标失去了对富营养化风险(叶绿素a)的指示意义,如通江浅水湖泊的总氮、总磷、透明度和高锰酸盐指数以及深水湖泊的总氮;第二,部分富营养化理化指标和叶绿素a原有关系发生错位,比如对于深水湖泊总磷对叶绿素a的响应比TLI指数构建所采用的关系更加敏感.针对TLI理化指标评估在长江中下游湖库应用中存在的问题提出如下改进建议:1)结合长时间序列历史数据,基于分位数回归等方法构建特定湖泊的叶绿素a和理化参数的响应关系,开发“一湖一策”的评估公式;2)根据换水周期和湖泊面积水深比对进行湖泊分类,建立特定湖泊类型的叶绿素a和理化参数的响应关系,构建“一类一策”的评估公式;3)在富营养化评估结果中应分别量化富营养化状态参数(营养盐水平)和富营养化风险参数(叶绿素a)以及两者比值,但生物指标是富营养化评估的最终指示.现阶段我国富营养化评价和管理多为“全国一策”,可能很难满足经济高效的管理需求.因此,本研究所建议和综述的“一类一策”和“一湖一策”的湖泊富营养化评估方法对未来的湖泊生态管理可能具有重要意义.     

Short-term effects of changes in water management on the limnological characteristics and zooplankton of a eutrophic Mediterranean coastal lagoon (NE Iberian Peninsula)

The Ter Vell (NE Iberian Peninsula) is a eutrophic coastal lagoon which has been flooded by the excess irrigation water and the agricultural runoff during the last decades. Between 1999 and 2003, restoration measures were applied to improve its water quality. At the same time, but independently, agricultural water management drastically reduced the freshwater inflow. The short-term effects of these management actions on the limnological characteristics of the lagoon were analysed by comparing two hydrological cycles, one before (1999/2000) and the other one after (2002/2003) the actions. The two cycles are illustrative of opposite situations in the hydrological functioning of coastal wetlands. In the first, the lagoon was exorheic, with prolonged flooding periods and a low residence time; in the second, it had a more endorheic character, with scarce water inputs and prolonged periods of confinement. Consequently, nitrogen inputs diminished and organic load and salinity increased as the internal loading and the accumulation effects became more relevant. These effects were actually caused by the drastic reduction in the freshwater inflow which prevented, in turn, the success of the restoration measures. The zooplankton community of the Ter Vell lagoon was not significantly altered by the hydrological change, at least in the short-term, and rotifers and cladocerans, mainly those species indicative of eutrophy, dominated the community.     

Age and associated stress field of middle Miocene back-arc basalt magmatism in Northeast Japan

A large volume of middle Miocene basaltic rocks is widely distributed across the back-arc region of Northeast Japan, including around the Dewa Mountains. Petrological research has shown that basaltic rocks of the Aosawa Formation around the Dewa Mountains were generated as a result of the opening of the Sea of Japan. To determine the precise ages of the middle Miocene basaltic magmatism, we conducted U–Pb and fission-track (FT) dating of a rhyolite lava that constitutes the uppermost part of the Aosawa Formation. In addition, we estimated the paleostress field of the volcanism using data from a basaltic dike swarm in the same formation. The rhyolite lava yields a U–Pb age of 10.73 ±0.22 Ma (2σ) and a FT age of 10.6 ±1.6 Ma (2σ), and the paleostress analysis suggests a normal-faulting stress regime with a NW–SE-trending σ₃-axis, a relatively high stress ratio, and a relatively high magma pressure. Our results show that the late Aosawa magmatism occurred under NW–SE extensional stress and ended at ~ 11 Ma.