Seasonal constraint of dynamic water temperature on riverine dissolved inorganic nitrogen transport in land surface modeling

水体温度变化对河流可溶性无机氮(DIN)输送有着强烈控制作用.然而,在全球尺度上河流DIN输送量对水温度变化的响应尚不清楚.因此,本文基于陆面过程模式,耦合河流水温估算和DIN传输方案,设定有,无动态水温情景,对比研究陆面模拟中水温变化对河流DIN通量变化的影响.结果表明:在考虑水温动态变化后,在30°N和30°S之间, DIN通量年振幅减小5%–25%.在中国东部地区,水温动态变化使河流DIN通量在夏季减少1%–3%,在冬季增加1%–5%,对DIN通量具有明显的季节性约束作用,表明动态水温的表达在河流DIN输送模拟中的重要性.

Bibliometrics-based Research Hotspots and Development Trends in Eco-hydrology of Dammed Rivers

Water conservation initiatives satisfy the demand for water supply,electricity generation,irrigation,and flood control.While helping humanity,they have also altered the ecosystem of natural rivers,impacted river ecology,disrupted river continuity,and jeopardized the existence of aquatic creatures in rivers.Studying the impacts of dam construction on rivers can enhance our knowledge of river ecological and environmental concerns and help sustain the health of river ecosystems,thereby realizing the harmony between humans and water in both theoretical and practical aspects.This study used bibliometrics and constructed an author-keyword 2-mode matrix network using Co-Occurrence software to identify the hotspots and research trend in eco-hydrology of dammed rivers.We identified‘FLOW’‘SEDIMENT’‘QUALITY’and‘MODEL’as the research hotspots in the ecological impact of dammed rivers,and combined the related literatures,we highlight the research progress in the four directions.Then the research shortcomings and prospect were discussed,including strengthening the monitoring and analysis of critical ecological variables,enhancing the hydrological monitoring density for small rivers,strengthening the research of relationship between eutrophication and zooplankton,establishing multiscale approaches,and combining multi-sources information technologies to improve parameter accuracy in the model research.

Improvement and Evaluation of the Latest Version of WRF-Lake at a Deep Riverine Reservoir

The WRF-lake vertically one-dimensional(1D)water temperature model,as a submodule of the Weather Research and Forecasting(WRF)system,is being widely used to investigate water-atmosphere interactions.But previous applications revealed that it cannot accurately simulate the water temperature in a deep riverine reservoir during a large flow rate period,and whether it can produce sufficiently accurate heat flux through the water surface of deep riverine reservoirs remains uncertain.In this study,the WRF-lake model was improved for applications in large,deep riverine reservoirs by parametric scheme optimization,and the accuracy of heat flux calculation was evaluated compared with the results of a better physically based model,the Delft3D-Flow,which was previously applied to different kinds of reservoirs successfully.The results show:(1)The latest version of WRF-lake can describe the surface water temperature to some extent but performs poorly in the large flow period.We revised WRF-lake by modifying the vertical thermal diffusivity,and then,the water temperature simulation in the large flow period was improved significantly.(2)The latest version of WRF-lake overestimates the reservoir-atmosphere heat exchange throughout the year,mainly because of underestimating the downward energy transfer in the reservoir,resulting in more heat remaining at the surface and returning to the atmosphere.The modification of vertical thermal diffusivity can improve the surface heat flux calculation significantly.(3)The longitudinal temperature variation and the temperature difference between inflow and outflow,which cannot be considered in the 1D WRF-lake,can also affect the water surface heat flux.

Riverine Ecology Restoration through Ecological Engineering and Naturalization

[Objective] The aim was to improve and restore destroyed riverine and water ecosystem and to prevent bio-diversity from deteriorating in Jari demonstration plot in Ethiopia. [Method] Biological engineering and naturalization were made use of to protect nature and restore wetland as per Succession Theory. [Result] Both of eco- environment and eco-functions of Mille River were restored through reconstruction of biocenosis in wetlands. [Conclusion] It is feasible to implement matched ecological projects in semiarid regions in East Africa, providing references for restoration and protection of local water resources.

Testing coral paleothermometers(B/Ca, Mg/Ca, Sr/Ca, U/Ca and δ^(18)O) under impacts of large riverine runoff

Sea surface temperature （SST） proxies including B/Ca, Mg/Ca, St/Ca, U/Ca and δ180 were analyzed in the skeleton of a Porites coral collected from the Zhujiang River （Pearl River） Estuary （ZRE）. These geochemical proxies are influenced by river runoff and this area of the northern South China Sea is strongly affected by seasonal freshwater floods. We assessed the robustness of each SST proxy through comparison with the local instrumental SST. Coral St/Ca shows the highest correlation with SST variations （r2=0.59）, suggesting St/Ca is the most robust SST proxy. In contrast, coral δ180 （r2=0.46）, B/Ca （r2=0.43） and U/Ca （r2=0.41） ratios were only moderately correlated with SST variations, suggesting that they are disturbed by some other factors in addition to SST. The poor correlation （r2=0.27） between SST and Mg/Ca indicates that Mg/Ca in coral skeletons is not a simple function of SST variations. This may ultimately limit the use of Mg/Ca as a coral paleothermometer.

Centrifugal model test on a riverine landslide in the Three Gorges Reservoir induced by rainfall and water level fluctuation

Frequent soil landslide events are recorded in the Three Gorges Reservoir area,China,making it necessary to investigate the failure mode of such riverside landslides.Geotechnical centrifugal test is considered to be the most realistic laboratory model,which can reconstruct the required geo-stress.In this study,the Liangshuijing landslide in the Three Gorgers Reservoir area is selected for a scaled centrifugal model experiment,and a water pump system is employed to retain the rainfall condition.Using the techniques of digital photography and pore water pressure transducers,water level fluctuation is controlled,and multi-physical data are thus obtained,including the pore water pressure,earth pressure,surface displacement and deep displacement.The analysis results indicate that:Three stages were set in the test(waterflooding stage,rainfall stage and drainage stage).Seven transverse cracks with wide of 1–5 mm appeared during the model test,of which 3 cracks at the toe landslide were caused by reservoir water fluctuation,and the cracks at the middle and rear part were caused by rainfall.During rainfall process,the maximum displacement of landslide model reaches 3 cm.And the maximum deformation of the model exceeds 12 cm at the drainage stage.The failure process of the slope model can be divided into four stages:microcracks appearance and propagation stage,thrust-type failure stage,retrogressive failure stage,and holistic failure stage.When the thrust-type zone caused by rainfall was connected or even overlapped with the retrogressive failure zone caused by the drainage,the landslide would start,which displayed a typical composite failure pattern.The failure mode and deformation mechanism under the coupling actions of water level fluctuation and rainfall are revealed in the model test,which could appropriately guide for the analysis and evaluation of riverside landslides.

Sand source and formation mechanism of riverine sand dunes: a case study in Xiangshui River, China

Riverine sand dunes develop as a result of fluvial-aeolian interactions. The primarily barchan dune chains along the Xiangshui River(a branch of the Xar Moron River in the western part of the Horqin Sandy Land of China) form a typical riverine dune field. We collected a series of samples from the riverine sand dunes parallel to the direction of the prevailing wind and investigated the sand sources and formation mechanisms of these dunes by determining the grain size, heavy mineral content and optically stimulated luminescence(OSL) of the samples. The sand of the near-river dunes was coarser than the sand of the dunes distant from the river, indicating that coarse sand of the valley mainly deposited on near-river dunes. The heavy mineral analysis suggested that wind-sand activity levels were intense on the upwind dunes, but relatively weak on the downwind dunes. This indicated that the sand sources for the near-river dunes were more abundant than those of the distant dunes. Our OSL analysis of samples suggested that the deposition rates on dunes near the river were greater than the deposition rates on dunes distant from the river. The development of dunes along the river indicated that the river played an important role in dune formation and development. In addition, airflow fluctuation and the formation of the waveform dunes had a type of feedback relationship. Grain size, heavy mineral and OSL analyses are widely used methods in wind-sand research. Sand dune grain size characteristics reflect the effects of airflow on the transport and separation of sand materials, as well as the physical characteristics of the sand sources. Heavy mineral characteristics are often used to investigate the relationships between sediments and sand sources. OSL indicates dune age, revealing formation of dunes. Therefore, it is useful to explore dune sand sources, as well as the mechanisms underlying dune formation, by determining grain size, heavy mineral content and OSL. This study investigated the sand sources of riverine dunes and provided new information about riverine dune formation and development.

RIVERINE SEDIMENTS AND CHINESE COASTLINE CHANGES

The tectonic uplifting and depression in the coastal zones results in the anormal distribution of riverine sediments. The coastal zones of tectonic depression areas received about 95% of the riveine sediments, whereas the tectonic uplift belts received only 5% of that, which is the main reason for the variety of the coastline types and the changes in the coastline. On the basis of this anormal distribution of riverine sediments in Chinese coastline, this paper discusses the scope and time of the maximum transgression, the trend, rate and period of the coastline changes, and the impact of riverine sediments on the future changes in coastline.

Spatial Distribution of Plant-Associated Invertebrates and Environmental Bioassessment in a Natural Riverine Lake (Lake Fibreno, Central Italy)

Lake Fibreno is a Mediterranean riverine lake located in Central Italy and fed by large flows of groundwater and characterized by the presence of a wide reed stand area and of the only floating island of the South Europe. It is enclosed in a Natural Reserve recognized as Special Area of Conservation (SAC-IT6050015) for the presence of habitats and species (92/43/EEC) of relevant scientific interest. In this paper, we compare the plant-associated meio-macrobenthic invertebrates among sites with different environmental characteristics. Both vegetation and invertebrates of Lake Fibreno were well diversified and abundant and were composed of a mixing of species typical of lentic and lotic waters. Our results show that a gradient of orthophosphate and nitrite contents and current velocity appeared to be the driver factors affecting the flora and fauna spatial distribution at the sampling sites. To obtain a bioassessment of the ecological quality of the vegetation zone, we compared the riverine Lake Fibreno with typical lentic lakes previously studied in Central Italy. We selected metrics, such as macrophyte belt extent and taxa richness, invertebrate species richness and Shannon diversity, ETOM (Ephemeropta + Trichoptera + Odonata + Mollusca), ETOC (Ephemeropta + Trichoptera + Odonata + Coleoptera) and LCrM (Large Crustacea + Mollusca). The comparison indicated a good ecological status of the vegetation zone of Lake Fibreno mainly due to the continuous washout effects (dilution and fast water removal) which reduce the nutrient content available for phytoplankton and maintain the high transparency and good oxygenation of the lake waters.

Wuzhen -- ＂the Last Riverine Town in China＂

Wuzhen is a typical riverine town south of the Yangtze River.Due to the World Internet Conference being held there,it seems to have become a place where CEOs a nd bosses of inter net compa n ies working on plans for the industry’s development gather.

Fluxes of riverine nutrient to the Zhujiang River Estuary and its potential eutrophication effect

The Zhujiang River Estuary is becoming eutrophic due to the impact of anthropogenic activities in the past decades.To understand nutrient dynamics and fluxes to the Lingdingyang water via four outlets(Humen,Jiaomen,Hongqimen and Hengmen),we investigated the spatial distribution and seasonal variation of dissolved nutrients in the Zhujiang River Estuary,based on fourteen cruises conducted from March 2015 to October 2017,covering both wet(April to September)and dry(October to March next year)seasons.Our results showed that riverine fluxes of dissolved inorganic nitrogen(DIN)and dissolved silicate(DSi)into the Lingdingyang water through four outlets varied seasonally due to the influence of river discharge,with the highest in spring and the lowest in winter.However,riverine flux of phosphate exhibited little significant seasonal variability.Riverine nutrients into the Lingdingyang water most resulted through Humen Outlet.The estuarine export fluxes of DIN out of the Zhujiang River Estuary derived from a box model were higher than fluxes of riverine nutrients in May,likely due to the influence of local sewage,while lower than riverine flux in August.The export fluxes of phosphate were higher than the fluxes of riverine phosphate in May and August.In contrast,large amounts of DSi were buried in the estuary in May and August.Although excess DIN was delivered into the Zhujiang River Estuary,eutrophication effect was not as severe as expected in the Zhujiang River Estuary,since the light limitation restricted the utilization of nutrients by phytoplankton.

Prevalence and risk assessment of antibiotics in riverine estuarine waters of Larut and Sangga Besar River, Perak

Antibiotics released into the environment through anthropogenic activities exert selective pressure,driving bacteria towards increasing antimicrobial resistance.The prevalence of antibiotics and the ecological risks posed in the riverine estuarine of Larut River and Sangga Besar River,which included wastewater effl uents from hospital,zoo,and poultry slaughterhouse sources were investigated.Solid phase extraction(SPE)followed by high-performance liquid chromatography tandem mass chromatography(HPLC-MS/MS)were used to extract and quantify the antibiotic residues from 22 antibiotics belonging to six major antibiotic classes(sulfonamide,macrolide,fl uoroquinolone,phenicol,trimethoprim,and tetracycline).Sixteen antibiotic residues were detected with concentrations ranging from limit of detection(LOD)to 1262.3 ng/L.Fluoroquinolones and macrolides were the most frequently detected compounds.Erythromycin,clarithromycin,and ofl oxacin detected in hospital and zoo effl uents posed a high risk to algae while tetracycline had low to medium ecological risks toward all the relevant organisms from aquatic environments(algae,invertebrate Daphnia magna,and fi sh).

RIVERINE INORGANIC CARBON DYNAMICS:OVERVIEW AND PERSPECTIVE

Inorganic carbon, the great part of the riverine carbon exported to the ocean, plays an important role in the global carbon cycle and ultimately impacts the coupled carbon-climate system. An overview was made on both methods and results of the riverine inorganic carbon researches. In addition to routine in situ survey, measurement and calculation, the direct precipitation method and the gas evolution technique were commonly used to analyze dissolved inorganic carbon in natural water samples. Soil CO2, carbonate minerals and atmospheric CO2 incorporated into riverine inorganic car- bon pool via different means, with bicarbonate ion being the dominant component. The concentration of inorganic carbon, the composition of carbon isotopes （8^13C and △^14C）, and their temporal or spatial variations in the streams were controlled by carbon input, output and changes of carbon biogeochemistry within the riverine system. More accurate flux es- timation, better understanding of different influential processes, and quantitative determination of various inputs or outputs need to be well researched in future.

An Eco-Hydrology Wireless Sensor Demonstration Network in High-Altitude and Alpine Environment in the Heihe River Basin of China

The emerging of Wireless Sensor Network (WSN) technology has brought new opportunities for data intensive observation in eco-hydrological research and environment monitoring. To make up for the insufficiencies of space observation data for models in eco-hydrology processes research of inland river basin which constrain the construction of accurate modeling and simulation, a sub-basin of the Heihe River Basin named Hulugou has been selected to perform the deployment and research for wireless sensor network from the perspective of eco-hydrology. In this paper, we discussed the system framework, the demonstration research area, the deployment of sensor nodes and the network topology of wireless sensor network. Finally, the study has summarized existing problems and experiences of wireless sensor network in these eco-hydrological applications and the available researches in hard environment. In the future, we will deploy a large number of sensor nodes in the long-term fine-grained eco-hydrological elements observing environment to form lots of homogeneous or heterogeneous wireless sensor networks.

沿江城市降雨特性及雨洪关系分析——以四川泸州市为例

沿江城市气候多变,外洪和内涝之间关系复杂,相互影响、相互制约,洪涝统筹是沿江城市面临的最主要问题。分析掌握沿江城市的暴雨、洪水特征,可提前预测不同降雨条件下河道洪水的特性及其对城区排涝的影响,对于城市防洪系统和排涝系统统筹兼顾、合理规划、洪涝预报预警,都具有重要意义。以四川泸州市为例,对暴雨时空分布特征、洪水特征规律等进行了分析探讨,以期为新形势下沿江城市防洪减灾体系建设提供参考。

江域生态伦理的论域及特殊性

江域生态伦理是生态伦理的特殊形态,有别于水伦理、河流伦理。从整体上看,江域生态伦理是以江域生态知识为基础的伦理价值研究,是对江域生态中主要伦理关系的研究,是对影响江域生态的伦理干预的研究。江域生态伦理论域首先涉及与生态伦理学、水伦理、河流伦理的关系,还涉及自身的伦理关系和基本原则。江域生态伦理的特殊性主要体现为发生场域的特殊性、角色定位的特殊性和研究视角的特殊性。

初级生产力主导了辽河水系颗粒态有机碳的来源

作为关键陆源物质,河流颗粒态有机碳(POC)的来源、输运及入海通量是当前关注的热点问题。然而,受水库等人类活动影响,河流颗粒碳的组分正在发生变化,这势必给陆地和海洋间碳的源汇过程和生物地球化学循环机制带来深刻影响。围绕上述问题,以辽河水系为研究区,于2023年7月沿河采集14个样品,将生物地球化学指标分析与最新的基因检测技术相结合,分析了POC含量和来源在流域内的变化规律,探讨了初级生产力主导辽河水系POC来源的可能机制,对比和总结了中国典型河流POC来源改变的共同趋势。研究结果显示,初级生产力是当前辽河水系POC的最主要来源,其中共球藻纲和蓝藻门生物是最主要贡献者;动物可能也是POC的重要来源,未来在分析POC来源时需加以重视;水库拦蓄效应可改变河流浮游生物的组成,进而对河流POC的来源产生重要影响;长江、黄河、珠江以及台湾岛和海南岛的诸多河流POC的浮游生物来源比例也在显著增加。上述趋势性变化,可能导致POC在流域-河口-陆架间的源汇格局发生剧烈变化,需要持续关注。

河流溶解无机碳稳定碳同位素示踪技术及其在中国河流碳循环研究中的应用

河流溶解无机碳(DIC)是全球碳循环中的重要组成部分,稳定碳同位素(δ^(13)C_(DIC))已被广泛用于辨识流域内碳的来源和迁移转化过程。通过综合现有文献,系统梳理河流δ^(13)C_(DIC)的影响因素和变化机理,论证了该指标能够真实、敏感反映流域环境特征及各种地表过程,可用于重建流域碳循环体系中的生物地球化学过程。由于河流碳来源及迁移转化过程的复杂性,关于河流δ^(13)C_(DIC)的影响机理仍有较多细节尚未探明。通过收集和分析中国主要河流的δ^(13)C_(DIC)数据发现,在全国尺度上我国河流δ^(13)C_(DIC)呈现出“西高东低”的变化格局,基本反映了我国地质、气候及生态环境的空间分布特征。青藏高原地区河流δ^(13)C_(DIC)整体上比其他地区明显偏高,关于这一现象的形成机制还有待进一步研究。未来可将δ^(13)C与放射性碳同位素(Δ^(14)C)联用并加强水体DIC稳定碳同位素分馏方面的基础理论研究,以期进一步完善和提升河流DIC同位素示踪理论及其在揭示碳循环过程和机理方面的应用。

“生态—效率”约束下工业用地减量化空间识别——以江苏省沿江经济带为例

研究目的:以生态保护与用地效率双重约束视角识别低效工业用地,探索其退出与利用转型路径,为工业用地减量化治理提供新思路。研究方法:基于“源地识别—廊道提取”研究范式构建区域生态安全格局,考虑生境隔离度评价并耦合低效工业用地评价构建工业用地分类治理四象限模型,综合判定江苏省沿江经济带工业用地减量化区域。研究结果:(1)江苏省沿江经济带共有52处生态源地,分布零散,呈现“江南多于江北”的空间格局,总面积3007.65 km~2,生态廊道共有134条,总长度2934.78 km,呈“西南多东北少”的分布格局。(2)无锡市、苏州市、南京市、常州市工业用地布局与生态用地之间冲突较为显著。(3)亟需腾退的工业用地总面积为82.10 km~2,集中分布于南京栖霞及江宁区、无锡惠山区、常州宜兴市、南通如东县、镇江京口区。研究结论:采用“生态—效率”双重约束能兼顾生态保护约束和效率提升需求,可以有效识别区域低效工业用地,为推进工业用地减量化提供科学依据。