The use of a spatially heterogeneous simulation model for studying biotransformation processes of nitrogen and phosphorus compounds and the dynamics of oxygen dissolved in water in the ecosystem of Neva Bay, the Gulf of Finland: 2. Input data for calculations, modeling results, and their analysis

The data collected for model calculations is systematized for natural and design conditions. The natural conditions did not take into account the effect of the complex of water-protection structures on the hydrological regime of Neva Bay and on the biogenic load onto this water area, while the design conditions, conversely, reflected the possible impact of those structures on the hydrology and ecology of the area. Numerical experiments were used to study the processes of transformation of N and P compounds and the dynamics of dissolved O₂ in Neva Bay water area. In the comparison of the calculated and observed concentrations of biogenic substances, Theil criterion was evaluated to assess the adequacy of the model in reproducing the concentration fields of the distribution of biogenic substances over Neva Bay water area. The major qualitative and quantitative features of the formation of the spatial heterogeneity and the time variations in the concentrations of biogenic element compounds over Neva Bay water area are identified. Possible improvements of the model in the reproduction of the complex of processes that are of particular importance for the development of substance transformations in shallow ecosystems are considered.     

Environmental capacity of nitrogen and phosphorus pollutions in Jiaozhou Bay,China: Modeling and assessing

In recent years, with the development of society and economy of Qingdao, environment and ecosystem problems, for instance, red ties, become more and more serious in Jiaozhou Bay, China, because of the increasing pollutants discharged into it. In order to solve these problems, an eco-hydrodynamic model is constructed to estimate the marine environmental capacity of nitrogen and phosphorus nutrients in Jiaozhou Bay, whose simulation results are rational for the bay. According to the model, if the target is set to achieve water quality (grade II) in Jiaozhou Bay, the environmental capacity of dissolved inorganic nitrogen and phosphorus in one year are approximately 7800 and 840 tons, respectively. Thus our research offers necessary scientific foundation to the total loads control efforts in this area.     

Environmental capacity of nitrogen and phosphorus pollutions in Jiaozhou Bay, China: modeling and assessing

In recent years, with the development of society and economy of Qingdao, environment and ecosystem problems, for instance, red ties, become more and more serious in Jiaozhou Bay, China, because of the increasing pollutants discharged into it. In order to solve these problems, an eco-hydrodynamic model is constructed to estimate the marine environmental capacity of nitrogen and phosphorus nutrients in Jiaozhou Bay, whose simulation results are rational for the bay. According to the model, if the target is set to achieve water quality (grade II) in Jiaozhou Bay, the environmental capacity of dissolved inorganic nitrogen and phosphorus in one year are approximately 7800 and 840 tons, respectively. Thus our research offers necessary scientific foundation to the total loads control efforts in this area.     

Modeling total maximum allocated loads for heavy metals in Jinzhou Bay,China

With the recent development of society and economy in the cities of Huludao and Jinzhou, Liaoning Province, China, environment and ecosystem problems have become increasingly serious in Jinzhou Bay, China, because of the increasing amount of heavy metal pollutants being discharged. To solve these problems, a water quality model of heavy metals coupled with a 3D hydrodynamic model is constructed to estimate the environmental capacity (EC) and total maximum allocated loads (TMALs) for Zn and Cd of three river catchments in Jinzhou Bay. According to the model, the ECs for Zn and Cd are approximately 17 and 8 tons per month, respectively, if the criterion obtained from HC₅ values (fifth percentile of the SSD) is set as the control criterion (8.24 μg/L for Zn and 3.83 μg/L for Cd) in Jinzhou Bay, and the TMALs of the three river catchments are 4 and 1.7 tons per month.     

Ecological evaluation of the Cumberland Basin ecosystem model

A holistic ecosystem simulation model has been developed for the Cumberland Basin and upper Chignecto Bay, a turbid macrotidal estuary at the head of the Bay of Fundy. This one-dimensional deterministic model has three compartments, three boundaries and three interacting submodels (physical, pelagic and benthic). Twenty-eight biological state variables represent broad functional groups of organisms and non-living organic carbon pools. All major components of the estuarine ecosystem are included. At the present stage of development, individual pelagic state variables give reasonable annual simulations which are in general agreement with available calibration data. Major problems remain with some benthic state variables, especially the subtidal ones about which little is known. In aggregate, the model performs well and output at the ecosystem level agrees with field observations. In the Cumberland Basin water column, annual community respiration exceeds phytoplankton net production (1–3 g C m⁻³) by a factor of 2–5 suggesting the importance of carbon imported from surrounding saltmarshes and the seaward boundary. Annual community respiration and microalgal net production (28 g C m⁻²) on the other hand are closely balanced in intertidal sediments. Respiration in subtidal sediments is entirely dependent upon sedimented carbon. The model supports the hypothesis that the Cumberland Basin is a heterotrophic ecosystem with low primary production which requires imported organic carbon to support the production and respiration of higher trophic levels.     

Field measurement and modeling of near-bed sediment transport processes with fluid mud layer in Tokyo Bay

Tokyo Bay is one of the estuaries in Japan with a high population of almost 26 million people in the basin area. One of the major concerns for the environment in this water area is the decreasing ecosystem functions including the deterioration of water and sediment qualities caused by various anthropogenic activities. Since the bottom sediments around almost the entire area of the inner bay consist of fine materials with a high organic content, which cause the deterioration of water quality through processes such as hypoxia, an understanding of the fine sediment dynamics in the Bay is crucial for an environmental assessment of the water area. This paper proposes a model for the key processes of fine sediment dynamics, which reflects field data about muddy bed structures and their dynamics obtained during the monitoring campaign in 2007. One of the specific features of the sediment in the Bay at present is the persistent existence of fluid mud layers (water content over 300 %) with a thickness of around a few decimeters, which might be caused by deposition of abundant organic particles due to eutrophication. The present study shows that diffusion flux model delivers quite reliable results for estimating erosion flux from the top of fluid mud layers after calibrating the model parameter against the time series data of vertical flux measured by an acoustic Doppler velocimeter system. This study also derives analytical solutions, based on the Bingham fluid concept, of advection flux in the fluid mud layer on which external shear stress force is applied.

     

Field measurement and modeling of near-bed sediment transport processes with fluid mud layer in Tokyo Bay

Tokyo Bay is one of the estuaries in Japan with a high population of almost 26 million people in the basin area. One of the major concerns for the environment in this water area is the decreasing ecosystem functions including the deterioration of water and sediment qualities caused by various anthropogenic activities. Since the bottom sediments around almost the entire area of the inner bay consist of fine materials with a high organic content, which cause the deterioration of water quality through processes such as hypoxia, an understanding of the fine sediment dynamics in the Bay is crucial for an environmental assessment of the water area. This paper proposes a model for the key processes of fine sediment dynamics, which reflects field data about muddy bed structures and their dynamics obtained during the monitoring campaign in 2007. One of the specific features of the sediment in the Bay at present is the persistent existence of fluid mud layers (water content over 300?%) with a thickness of around a few decimeters, which might be caused by deposition of abundant organic particles due to eutrophication. The present study shows that diffusion flux model delivers quite reliable results for estimating erosion flux from the top of fluid mud layers after calibrating the model parameter against the time series data of vertical flux measured by an acoustic Doppler velocimeter system. This study also derives analytical solutions, based on the Bingham fluid concept, of advection flux in the fluid mud layer on which external shear stress force is applied.     

Toxicity bioassay of bottom sediments in large water bodies in Northwestern Russia with the use of crustaceans

The results of bioassay and physicochemical analysis of bottom sediments from large water bodies in Northwestern Russia are presented. The water bodies under consideration include Lake Onega, Vygozerskoe Reservoir, and freshwater part of the Neva Estuary (the Eastern Gulf of Finland), which are locally subject to eutrophication and toxic pollution. The potential toxicity of bottom sediments, evaluated by the survival rate of two crustacean species (Gmelinoides fasciatus and Ceriodaphnia affinis) in 7-day tests, varied from high to low values, characterizing 5 quality classes: high, good, moderate, poor, and heavy, with appropriate degrees of toxic pollution from no to very high pollution. Bad zones were identified in the Kondopoga and Petrozavodsk bays of Onega Lake, the northern and southern parts of the Vygozerskoe Reservoir, and the southern part of the Neva Bay near the dam. Bottom sediments were found to have high quality in the open central areas of Lake Onega and the Vygozerskoe Reservoir and in the western part of Neva Estuary.     

逸度模型在湖泊流域农药多介质归趋研究中的应用与展望

农药的施用在促进农业经济发展的同时,也带来了诸多环境问题.农药由农业活动排放进入到环境后会通过不同的途径在各介质之间进行迁移和转化,最后由径流作用汇聚于湖泊中,破坏生态环境,影响人类健康.因此,研究湖泊流域生态系统中农药的多介质归趋具有重要意义.使用基于逸度的多介质模型模拟农药在环境中的行为是一个十分有效的方法.逸度模型利用"逸度"的概念描述污染物在各个环境介质之间的迁移和转化过程趋势,其结果建立在化学物质自身物化性质和环境系统性质之上,不仅适用于预测农药在环境各介质中的残留水平,还可以揭示区域内污染的空间分布特征,是湖泊流域生态系统管理中一个重要的工具.本文综述了逸度模型的理论基础,对近年来国内外逸度模型的发展现状、相关环境模型及其在农药归趋研究和湖泊流域生态系统管理中的运用进行了总结,并展望了逸度模型在农药多介质研究中的应用前景,以期对我国农药的管理、合理施用方面提供科学与技术支持.     

Modelling ice conditions in the easternmost Gulf of Finland in the Baltic Sea

To model ice conditions in the eastern Gulf of Finland, a high-resolution three-dimensional hydrodynamic model is coupled with the advanced sea-ice model HELMI (Haapala et al., 2005). To test the model in extreme situations, the ice pattern in the eastern Gulf of Finland was simulated for a mild ice winter (2007–2008) and for a moderate one (2003–2004). The reference runs were performed on the assumption that the ice in the model domain is fast ice if the sea depth is less than 10 m. Using this assumption, the ice thickness averaged over the Neva Bay (the easternmost part of the Gulf of Finland) is overestimated by the model for almost the entire wintertime in the mild winter and during the ice formation and melting periods in the moderate winter, as compared with the thickness reported in ice charts.     

Estimating the Anthropogenic Impact on Water Bodies Using a Simulation Mathematical Model of Phosphorus System

A simulation model of the phosphorus system is used to study the ecosystems functioning in the Dautkul'skoe Reservoir and Shegekul Lake (Mezhdurech'e). Dependence of the internal flows (turnover) and normal annual concentrations of P forms in the water body on its external load onto the ecosystem is established. The budgets of P and its production–destruction flows (1993–1999), calculated using the model, are presented and analyzed. Comparison estimates are made for the anthropogenic impact on the water bodies of the southern Aral Sea region.     

Spatial-temporal variations in organic matter of the Sea of Azov

The spatial-temporal variations in the amount and biochemical composition of organic matter and the rates of its transformations in the ecosystems of the Russian part of the Sea of Azov are analyzed. Maximum OM concentrations are typical for Taganrog Bay. A characteristic feature of the Sea of Azov is a large proportion of particulate organic matter, which in summer in Taganrog Bay exceeded 35%. It is shown that not only the concentration of organic matter changes from season to season, but also its elementary (C_org, N_org, and P_org) and biochemical composition (proteins, carbohydrates, and lipids). The major biochemical compound of dissolved organic matter is shown to be carbohydrates (13–28%), and that of particulate matter is protein (44–51%). The hydrolytic (phosphatase and protease) and oxidation-reduction enzymes of electron-transport system demonstrate a high activity in summer. The estimated short turnover times of phosphates and protein suggest the rapid and complete utilization of organic matter in the Sea of Azov.     

Determination and application of path duration of seismic ground motions based on the K-NET data in Sagami Bay,Japan

Duration models are one of the important parameters in ground-motion simulations. This model varies in different study areas, and plays a critical role in nonlinear structural response analysis. Currently, available empirical models are being globally used in ground-motion simulations, with limited research focusing on path duration in specific regions. In this study, we collected 6,486 sets of three-component strong-motion records from 29 K-NET stations in the Sagami Bay, Japan, and its surrounding areas between January 2000 to October 2018. We extracted the effective duration of 386 pieces of ground-motion records by manually picking up the S-wave arrival time and calculating the significant duration. We then obtained the path duration model of the study area based on the empirical equation of dynamic corner frequency and source duration of [7]. Compared with the results of the available empirical models, the Fourier spectrum of the simulated ground motion from our effective duration model showed higher accuracy in the long-term range, with less fitting residuals. This path duration model was then applied to simulate two earthquakes of M_W5.4 and M_W6.2, respectively, in the region using the stochastic finite-fault method with a set of reliable source, path, and site parameters determined for the study area. The simulation results of most stations fit well with observation records in the 0–30 Hz frequency band. For the M_W5.4 earthquake, the simulated ground motions at KNG005/KNG010/SZO008 stations were relatively weak in the mid to high frequency band (1–30 Hz) because the quality factor and geometric diffusion model used in the simulation were the averages of the entire Sagami Bay region, causing a bias in the results of a few stations owing to local crustal velocity anomalies and topographic effects. For the M_W6.2 earthquake, the simulated ground motions were relatively weak at all SZO and TKY stations, mainly because of the close distance from these stations to the epicenter and the complex seismic-wave propagation paths. The analysis suggests that the differences between the simulation results of the two earthquakes were mainly related to complex geological conditions and seismic-wave propagation paths.     

Assessing health of the Bay of Fundy--concepts and framework

A discussion of health and ecosystem health (EH) concepts and a conceptual framework for assessing health of the Bay of Fundy are presented. The framework includes:Concepts--What is health? What is EH and marine ecosystem health (MEH)? How does EH relate to other closely related concepts and principles i.e. environmental quality (especially marine or MEQ), ecosystem integrity, and ecosystem sustainability?Importance--Why is EH important, and what are the linkages to people i.e. human health?Approaches and techniques--How do we monitor and measure EH, and in that context, ecosystem or ecological change? i.e. What are the monitoring approaches and tools? What is an appropriate set of EH indicators and indices for the Bay of Fundy and Gulf of Maine? At the present time, can we make unequivocal statements about the status and trends in EH measures of the Bay of Fundy? Do we have adequate guidelines, objectives and standards for assessing environmental quality and EH?Connecting with management needs--Do we have adequate mechanisms in place to address MEH, marine environmental quality (MEQ), and environmental sustainability in the Bay of Fundy? What is the role of periodic marine assessments (state of the marine environment reports) in this activity? What kinds of new directions and new ecosystem science should be given priority? What kinds of other new activities should be pursued?For the Bay of Fundy Coastal Forum at the recent 5th BOFEP Bay of Fundy Science Workshop (May 2002), five core questions flowing from the health framework served to initiate and focus the discussions:Current state--What is the present health or condition of the Bay of Fundy?Changes--Are conditions improving or deteriorating?Indicators--What kinds of indicators do we consider most useful in trying to answer these questions?Existing resources--Are there adequate resources (e.g. institutional, financial, scientific, regulatory) to protect or restore the health of the Bay?Needs--What kinds of new information and approaches do we need to protect the health of the Bay?The background information and ideas of this paper were intended to assist discussion at the Fundy workshop, and to help identify the next steps, both individual and collective, for assessing the health of the Bay of Fundy.     

Rating Water Quality in Sevastopol Bay by the Fluxes of Pollutant Deposition in Bottom Sediments

Sevastopol Bay is used as an example for the development of criteria for rating anthropogenic impact by elimination fluxes from the water area of post-Chernobyl (⁹⁰Sr, ¹³⁷Cs, ^239,240Pu) and natural (²¹⁰Pо) radionuclides, as well as mercury and organochlorine compounds. The differentiation of the bay water area into zones with different biogeochemical conditions and the balance approach to interpreting field observation data were used to assess the conditioning capacity of Sevastopol Bay ecosystem for conservative radioactive and chemical substances by elimination fluxes of pollutants into aqueous depot, which is the open part of the Black Sea and into the geological depot, i.e., its bottom sediment stratum.     

Simulating spatiotemporal variations of atmospheric CO2 using a nested hemispheric model

A three-dimensional Eulerian nested model for transport, diffusion, and surface fluxes of CO₂ has been developed. The model is used to study the spatial and temporal variations of atmospheric CO₂ concentrations as a step towards a better understanding of the regional source pattern over Europe. The influence from the national surface characteristics, as e.g. fossil CO₂ emissions or ecosystem fluxes, can be treated on a continental or national level in the model. In the future the model can be used as a mean to corroborate national and EU-wide controls or reductions of carbon emissions. One of the major questions in the estimation of e.g. national CO₂ budgets is the quantification of surface ecosystem fluxes. In order to test the sensitivity of atmospheric CO₂ concentrations to ecosystem fluxes, two different parameterizations [J. Geophys. Res. 92 (1987) 2999] and [Global Biogeochem. Cycles 10 (1996) 269] have been implemented in the model. The model both with and without nest is validated by comparison with measurements and the different model results will be discussed. The results show that including a nested domain with higher spatial resolution significantly improves the model performance in some areas. In spite of regional deviations in the two sets of ecosystems fluxes no major differences are seen over Europe as a whole when either of the two parameterizations are included in the model and the results compared.     

Modeling studies of tidal dynamics and the associated responses to coastline changes in the Bohai Sea,China

Over the past 30 years, reclamation projects and related changes have impacted the hydrodynamics and sediment transport in the Bohai Sea. Three-dimensional tidal current models of the Bohai Sea and the Yellow Sea were constructed using the MIKE 3 model. We used a refined grid to simulate and analyze the effects of changes in coastline, depth, topography, reclamation, the Yellow River estuary, and coastal erosion on tidal systems, tide levels, tidal currents, residual currents, and tidal fluxes. The simulation results show that the relative change in the amplitude of the half-day tide is greater than that of the full-day tide. The changes in the tidal amplitudes of M₂, S₂, K₁, and O₁ caused by coastline changes accounted for 27.76–99.07% of the overall change in amplitude from 1987 to 2016, and water depth changes accounted for 0.93–72.24% of the overall change. The dominant factor driving coastline changes is reclamation, accounting for 99.55–99.91% of the amplitude changes in tidal waves, followed by coastal erosion, accounting for 0.05–0.40% of the tidal wave amplitude changes. The contribution of changes in the Yellow River estuary to tidal wave amplitude changes is small, accounting for 0.01–0.12% of the amplitude change factor. The change in the highest tide level (HTL) is mainly related to the amplitude change, and the correlation with the phase change is small. The dominant factor responsible for the change in the HTL is the tide amplitude change in M2, followed by S2, whereas the influence of the K1 and O1 tides on the change in the HTL is small. Reclamation resulted in a decrease in the vertical average maximum flow velocity (V_VAM) in the Bohai Sea. Shallower water depths have led to an increase in the V_VAM; deeper water depths have led to a decrease in the maximum flow velocity. The absolute value of the maximum flow velocity gradually decreases from the surface to the bottom, but the relative change value is basically constant. The changes in the tidal dynamics of the Bohai Sea are proportional to the degree of change in the coastline. The maximum and minimum changes in the tidal flux appear in Laizhou Bay (P-LZB) and Liaodong Bay (P-LDB), respectively. The changes in the tidal flux are related to the change in the area of the bay. Due to the reduced tidal flux, the water exchange capacity of the Bohai Sea has decreased, impacting the ecological environment of the Bohai Sea. Strictly controlling the scale of reclamation are important measures for reducing the decline in the water exchange capacity of the Bohai Sea and the deterioration of its ecological environment.     

Cross-Media Models of the Chesapeake Bay Watershed and Airshed

A continuous, deterministic watershed model of the Chesapeake Bay watershed, linked to an atmospheric deposition model is used to examine nutrient loads to the Chesapeake Bay under different management scenarios. The Hydrologic Simulation Program - Fortran, Version 11 simulation code is used at an hourly time-step for ten years of simulation in the watershed. The Regional Acid Deposition Model simulates management options in reducing atmospheric deposition of nitrogen. Nutrient loads are summed over daily periods and used for loading a simulation of the Chesapeake estuary employing the Chesapeake Bay Estuary Model Package. Averaged over the ten-year simulation, loads are compared for scenarios under 1985 conditions, forecasted conditions in the year 2000, and estimated conditions under a limit of technology scenario. Limit of technology loads are a 50%, 64%, and 42% reduction from the 1985 loads in total nitrogen, total phosphorus, and total suspended solids, respectively. Urban loads, which include point source, on-site wastewater disposal systems, combined sewer overflows, and nonpoint source loads have the highest flux of nutrient loads to the Chesapeake, followed by crop land uses.on assignment from NOAA Air Resources Laboratory     

A coastal prediction system as an event response tool: Particle tracking simulation of an anhydrous ammonia spill in Tampa Bay

A coastal prediction system for Tampa Bay, comprised of a numerical circulation model and Lagrangian particle transport model, rapidly produces hindcast/forecast simulations that alert authorities to high impact areas following the introduction of hazardous material into the bay. The effectiveness of the prediction system as an event response tool is evaluated during an anhydrous ammonia spill. A week-long simulation predicts the trajectory of the material due to winds and currents. Physical transport of the model particles alternates from being tidally driven to being driven both by wind action and residual circulation. A forecast simulation showing particle distribution drove field sampling that resulted in the detection of a Pseudo-nitzschia bloom likely initiated from excess ammonium in the bay. An online component of the coastal prediction system is in development to better manage response and mitigation efforts for future hazardous material spills in Tampa Bay.     

湖沼学是研究内陆水体的多学科整合科学——兼论我国湖沼学发展面临的挑战与机遇

湖沼学是研究内陆水体的多学科交叉综合性科学,自从Forel F.A.于1892年首次对湖沼学做出定义以来已有近130年历史.湖沼学的主要分支学科包括地质湖沼学(包括古湖沼学)、物理湖沼学、化学(生物地球化学)湖沼学和生物湖沼学.湖沼学的关键自然属性是通过跨学科的整合,从水生态系统水平综合分析相关过程与机理,并对生态系统变化进行预测.因此,湖泊学也是支撑水资源与生态系统保护、管理与修复的核心科学.然而,目前我国湖沼学发展面临分支学科发展不平衡、研究碎片化等问题,而人类活动加剧和气候变化对内陆水体生态系统的影响及管理对策是湖沼学研究面临的挑战与机遇.我国湖沼学研究亟需围绕人类活动、气候变化的影响,重点开展以下几个方面的工作:1)水动力与水文地貌特征变化及其环境生态效应; 2)营养盐和有机质生物地球化学循环及其环境生态效应; 3)食物网结构与功能; 4)外来入侵物种的影响与控制对策; 5)与水环境有关的传染病防治; 6)地表水生态评价; 7)生态系统演变机理与退化生态系统修复等.