Review and Analysis: Fate of Arsenic Applied to Canal Shipping Lane Vegetation and United States Military Base Grounds in the Panama Canal Zone

The opening of the Panama Canal in 1913 increased the availability of internationally traded goods and transformed ocean-shipping by shortening travel time between the Atlantic Ocean and Pacific Ocean. The canal sparked the growth of port authorities and increased ship tonnage on both coasts of Panama. Since the construction of the Panama Canal, in the 1910s, pesticides, herbicides and chemicals, including arsenic, have been essential for controlling wetland vegetation, including hyacinth, which blocked rivers, lakes, and the canal as well as managing mosquitoes. Pesticides and chemicals flowed into Lake Gatun (reservoir) either attached to sediment or in solution during the monsoon season. Lake Gatun was the drinking water source for most of the people living in the Panama Canal Zone. The United States military base commanders had the ability to order and use cacodylic acid (arsenic based) from the Naval Depot Supply Federal and Stock Catalog and the later Federal Supply Catalog on the military base grounds in the Panama Canal Zone. Cacodylic acid was shipped to Panama Canal Zone ports, including Balboa and Cristobal, and distributed to the military bases by rail or truck. The objective of this study is to determine the fate of arsenic: 1) applied between 1914 and 1935 to Panama Canal shipping lane hyacinth and other wetland vegetation and 2) cacodylic acid (arsenic) sprayed from 1948 to 1999 on the US military base grounds in the Panama Canal Zone.

Formation and water environmental evolution of the Nansihu Lake

Through high-resolution research of sedimental chronology and the sediment environmental indexes, such as graininess, minerals, magnetic parameters, pigment content, organic carbon and chronology in Ds-core and Ws-core in Nansihu Lake, the authors analyze the formation cause of the Nansihu Lake and its water environmental changes. Historical documents are also analyzed here in order to reach the conclusion. Researches indicate that the Nansihu Lake came into being about 2500 aBP and its evolution succession can be divided into four stages. In this evolution process, several scattered lakes merge into one large lake in the east of China. This process is distinctively affected by the overflow of the Yellow River, the excavation of the Grand Canal and other human activities.

Area, isolation, disturbance and age effects on species richness of summer waterbirds in post-mining subsidence lakes,Anhui, China

Background: The species–area relationship is one of the best documented patterns in community ecology.Factors influencing species–area relationship are still not well understood.Since the proposal of the equilibrium theory of island biogeography, many studies have tested the effects of area and isolation, estimating effects of disturbance and patch age were scarce and should also be important bearing.Methods: We investigated summer waterbird species richness in 38 post?mining subsidence lakes in Huainan and Fuyang, Anhui, China, May 25–June 12, 2016.We examined the effects of lake area, isolation(distance to natural water bodies), aquaculture disturbance, lake age and lake state(still sinking or not sinking) on summer waterbird species richness with multivariable linear regression method and model selection method.Results: Our results from multivariable linear regression and model selection were consistent, which showed that species richness was positively related with lake area and negatively related with isolation.Aquaculture disturbance negatively influenced species richness.Highest species richness were found in lakes under intermediate intensity of aquaculture activities with area less than 100 ha and lakes under low intensity of aquaculture activities with area greater than 100 ha.Lake age and lake state had no significant effects on species richness.Conclusions: Species richness was most related with lake area, aquaculture disturbance, and isolation, with lake area had a positive effect, while aquaculture activities and isolation had a negative effect.What's more, aquaculture activi?ties significantly changed the slope of species–area relationship and might impede us finding a relationship between species richness and lake age.

New recognitions to genesis and exploitation of the Xuxi River in Jiangsu Province

Along the north bank of the Xuxi River, the sand-intercalated-muddy gravel layer from -3.7 - -5.8 m in the borehole 7508 at the East Dam and the middle, coarse and fine sand layer with a thickness of 4.5 m at the lower part of the borehole 8179 between the East Dam and the West Dam indicate that a large natural river was here before the Kingdom of Wu excavated the Xuxi Canal. The existence of Neolithic sites such as Xuecheng, Chaoduntou and Xiajiadang along the Xuxi River and the silt layer with dozens of meters archived under the earth＇s surface within a range of 1 km along both banks are the even more important evidences for the existence of the ancient Zhongjiang River. The floodgate of the East Dam nowadays makes against the communication between the Shuiyangjiang River and the Taihu Lake. The authors suggest the canal between Wuhu and Taihu Lake should be excavated as soon as possible, namely, the navigation channel from Wuhu through Guchenghu Lake, Xuxi River, East Dam, Liyang, Yixing to Taihu Lake should be further widen and the deposits composed of slope wash on the watershed between Shuiyangjiang River and Taihu Lake should be dredged away. Then, the channel journey can be shortened, the boats in ship transportation on the Yangtze River can be shunted to ensure the security of shipping, the resources of sand and gravel in the old river channel can be exploited and the dike of the Yangtze River can be reinforced. So, the problems of irrigation, flood diversion, pollution abatement and drainage of flooded fields in the lower Yangtze River will be resolved. Then, the above methods can impel the sustainable development of the Xuxi River and Taihu Lake area.

Impact of land use change on water quality in the Dianchi Lake watershed, Yunnan, China, 1988-2008

Land use changes occurring in China during the time period of rapid economic development are linked to the degradation of water quality in streams and lakes. This paper examines these linkages in the Dianchi Lake watershed in Yunnan in southwest China based on a twenty-year data set from 1988 to 2008. Pearson correlation analysis and simple linear regression analysis are employed to explore the relationships between land use change and water quality of two sub-basins, the Caohai Lake basin and the Waihai Lake basin, within the Dianchi Lake watershed. Land use categories more strongly correlate to water quality in the Caohai Lake basin than that in the Waihai Lake basin. The different structure of land use categories, spatial distribution of land cover, and scales of buffer zones could be the factors resulting in the dissimilarities between these two lakes. The research can provide valuable insights for policymakers into land use management in order to curb further water degradation in Dianchi Lake.

Mechanical properties of nerve roots and rami radiculares isolated from fresh pig spinal cords

No reports have described experiments designed to determine the strength characteristics of spinal nerve roots and rami radiculares for the purpose of explaining the complexity of symptoms of medullary cone lesions and cauda equina syndrome. In this study, to explain the pathogenesis of cauda equina syndrome, monoaxial tensile tests were performed to determine the strength characteristics of spinal nerve roots and rami radiculares, and analysis was conducted to evaluate the stress-strain relationship and strength characteristics. Using the same tensile test device, the nerve root and ramus radiculares isolated from the spinal cords of pigs were subjected to the tensile test and stress relaxation test at load strain rates of 0.1, 1, 10, and 100 s-1 under identical settings. The tensile strength of the nerve root was not rate dependent, while the ramus radiculares tensile strength tended to decrease as the strain rate increased. These findings provide important insights into cauda equina symptoms, radiculopathy, and clinical symptoms of the medullary cone.

Morphological Characteristics of Cambodia Mekong Delta and Tonle Sap Lake and Its Response to River-Lake Water Exchange Pattern

Tonle Sap Lake is the largest river-connected lake, buffer area and ecological zone of Mekong River, which plays a huge role in dispelling flood peak and compensating water, and the conservation of biological diversity. The river-lake relationship between Mekong River and Tonle Sap Lake is unique and has always been a major focus in the international community. The land terrain and under-water topography were used to analyze the morphological characteristics of Cambodia Mekong Delta and Tonle Sap Lake. Long series of hydrological data of river-lake controlling stations were used to analyze the water level variation characteristics and water volume exchange pattern between Mekong River and Tonle Sap Lake, and the response relationship to river-lake morphological characteristics were also researched. The results show that: Cambodia Mekong Delta and Tonle Sap Lake Area is low-lying and flat with gentle channel gradient and water surface gradient, making the relationship between water level and area (or volume) smooth. The channel storage capacity of Mekong River and Tonle Sap River is not enough compared to the inflow, so vast flooding plain is extremely prone to be inundated, making the flood relationships between the left and right banks become very complicated. Tonle Sap Lake is a seasonal freshwater lake with water flowing in and flowing out, and the timing and intensity of water exchange with Mekong River are closely related to the water flow resistance at the exit section of Tonle Sap Lake and the cross-sectional area of Tonle Sap River, which can be reflected by the river-lake water level difference and the water level of Tonle Sap River. Affected by the river-lake morphological characteristics, the water exchange intensity between Mekong River and Tonle Sap Lake is great. Tonle Sap Lake not only stores 14.4% of flood volume (39.7 billion m3) from the Mekong River every year, but also supplies 29.7% of dry water (69.4 billion m3) to the Mekong River. Influenced by the adjustment of the floodplain, the water level fluctuation of Mekong River and Tonle Sap Lake is slow, and the rising and droop rates of water level are positively correlated with the floodplain storage area. The research results will help to understand the relationship mechanism between Mekong River and Tonle Sap Lake and provide a scientific basis for the comprehensive governance of Cambodia Mekong Delta and Tonle Sap Lake Area.

Research on the Synthetic Appraisal Index System of Lake Health

[Objective ] The study aimed at assessing the state of lake health. [ Method] Based on the concept of ＂healthy lakes＂ analyzed deeply, the fuzzy integrated evaluation was used to establish the evaluation index system of lake health, and the analytic hierarchy process （AHP） com- bined with expert evaluation method was used to determine the weight of each indicator. Afterwards, the health state of three typical lakes （ San- baidang, Beimayang and Qiaobeidang） in Wujiang City were evaluated by the system, and the measures to develop and protect the lakes were put forward finally. E Resultl The assessment results showed that Sanbaidang and Beimayang were in basic health, while Qiaobeidang was in sub- health. The indicator system and assessment method are suitable for the rivers in eastern plains of China.[ Conclusion] The research could provide scientific references for the development, protection and restoration of lakes.

Using quantile regression to analyze the stressor–response relationships between nutrient levels and algal biomass in three shallow lakes of the Lake Taihu Basin, China

Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used to interpret the stressor–response relationships between nutrient(e.g., phosphorus, nitrogen) concentrations and algal biomass as measured by chlorophyll-a(Chl-a) levels. QR results indicated that Lake Dianshan and Lake Changdang,which are both heavily eutrophicated, were P-limited only.In contrast, Lake Kuilei, which has significantly lower nutrient levels and algal biomass than the other two lakes,was P- and N-limited. Moreover, in Lake Kuilei, N and P levels had significant interaction effects on the algal biomass at the upper quantiles(s [ 0.68). The degree to which the lakes were P-limited increased with rises in the mean total P concentration in the lakes. QR has many advantages over ordinary least squares regression for discriminating limiting factors and, in particular, allows us to estimate changes near the upper extremes of distributions associated with limiting factors. QR is adapted to more specialized risk management problems, such as early warnings of the risk of algal blooms.The probable value-at-risk of harmful algal blooms for Lake Kuilei, Lake Dianshan and Lake Changdang is s = 0.76(Chl-a = 9 mg/m3), s = 0.87(Chl-a = 24 mg/m3) and s = 0.72(Chl-a = 35 mg/m3), respectively. Given the results of the stressor–response relationship analysis, we conclude that reductions in P input represent the most feasible and least costly approach for managing eutrophication in the shallow lakes of the Lake Taihu Basin. To control the magnitude and duration of algal blooms in shallow lakes,reductions in P and N inputs are required. The 95 % CI bounds of slopes indicated that the interactions of nonnutrient factors with nutrients had strong impacts on the algal biomass in lightly eutrophicated Lake Kuilei. It is suggested that, in addition to reductions in nutrient loads,several ecological measures, such as an increase in the biomass of submerged macrophytes and the reduction of hydraulic retention time by flushing, could represent important components of an integrated approach to eutrophication management in the Lake Taihu Basin.

基于文脉传承的运河与无锡城市发展关系探析

大运河文化带建设是当下社会关注的热点与焦点。无锡的城市发展与运河密切相关。通过分析运河与无锡城市发展的总体关系以及推动无锡段运河沿线发展的关键要素,基于文脉传承的视角,进一步探析了运河在无锡城市历史文脉的形成、传承与体验过程中的重要作用,并展望了运河与无锡城市未来的发展,希望能为相同类型的城市建设提供借鉴与参考。

An approach to extracting surface supply relationships between glaciers and lakes on the Tibetan Plateau

Surface supply relationships between glaciers and lakes are needed to analyze and understand hydrological processes at regional and global scales.However,these supply relationships still cannot be extracted efficiently by existing methods.This paper proposes an automatic and efficient approach to extracting surface supply relationships between glaciers and lakes based on meltwater flow paths.The approach includes two stages:(1)identifying direct connections between objects(i.e.glaciers and lakes)based on flow direction derived from digital terrain analysis on a gridded digital elevation model(DEM)and(2)deriving all(or user-specified)kinds of surface supply relationships based on graph search.All computation-intensive steps in this approach have been parallelized;and all steps in the proposed approach have been integrated as an automatic program.Results for the Tibetan Plateau show that given outline data for glaciers and lakes and the Shuttle Radar Topography Mission DEM,the proposed approach can automatically derive diverse surface supply relationships under userspecified restrictions on the attributes of the supply route.The parallelization in the approach effectively improves the computing efficiency.The proposed approach could also be applied to developing a detailed fundamental dataset of supply relationships between glaciers and lakes for other region or period.

Sustainable Ecosystem Management versus Economic Exploitation： A Case Study of Lake Naivasha Basin, Kenya

Human activities in the Lake Naivasha catchments pose serious ecological threats to sustainable freshwater ecosystem management. The future hangs on the balance of economic exploitation and sustainable watershed conservation. Water abstraction volumes, embedded water/virtual water and chemical analysis of wastewater discharges were assessed. Dissolved oxygen, temperature, Secchi disc depth, benthic organisms＇ population and pesticides used in the farms were determined. The study found that abstraction exceeds safe water yield, farms have also encroached on the riparian lands and connected to the lake through canals allowing effluents to flow directly to the lake. Benthic community populations are low at points where discharge canals enter the lake, indicating inflow of materials are toxic. Canal samples show high contaminant levels of actions for sustainable exploitation of the resource is essential. compared to other sites. Wise use of the resource and implementation The determination of ecological and water footprints are recommend.

Microalgal Epibiontic Communities on Some Brachyuran Crabs in Suez Canal, Egypt

The microalgal epibiontic communities of the brachyuran crabs Dorippe quadridens, Schizophrys aspera and Hyastenus hilgendorfi were studied during spring and summer of 2011. A total of 68 microalgal species of four phyla （Chlorophyta, Bascillariophyta, Cyanophyta and Pyrrhophyta） was recorded in the epibiosis of the investigated brachyuran crabs males and females Generally, Bascillariophyta predominate in number of species over the other microalgal groups, followed by Cyanophyta and Pyrrhophyta, while Chlorophyta was represented by the lowest number of species. Highly percentage of occurrence of microalgal epibionts was observed on the dorsal part of the investigated crabs followed by chela and ventral parts.

从流域视角探讨文化遗产保护

目前,文化遗产保护工作多在行政区划的框架内开展。然而现有的行政区划管理逻辑与人类文明和遗产形成的源起逻辑是大相径庭的。众所周知,早期人类依水而居,流域成为孕育人类文明的载体和城乡演变的见证。可以说,人水关系在人地关系中是最本质、经典且持久的。文章从流域视角切入,探讨文化遗产保护所呈现的“自然-人文”耦合的系统性特征,提出多尺度协调保护与系统性网络构建、跨学科整合与数据同化技术应用、与动态环境变化适应性响应策略等保护思路,并分析“黄-运-长”流域共同体中的两组人水互动模式的典型案例,从文化遗产的本质出发,为其保护与发展提供一个可持续的综合框架,以回应构建文化遗产大保护格局的时代要求。

关于黄河与河套古湖河湖关系演变的假说性分析——兼论对黄河内蒙古段生态治理的启示

黄河曾经在流经河套盆地过程中形成吉兰泰、乌兰布和、巴彦淖尔、呼包4个古湖,且在高湖面时期连成统一的“河套古大湖”,其后4湖分离并分别演绎了自己的河湖关系。在研习前人相关成果基础上,通过建立整体假说性解释框架,试图按照历史顺序与逻辑顺序统一的要求对该河段河湖关系的演变过程进行重建,并为与之相关的生态系统的治理提供借鉴。研究认为:主河道构建是黄河主动实施填湖、建堤、造槽并“甩湖”的过程与结果;冲积扇是黄河填湖的主要模式,而冲积扇顶附近凸起则是湖口淤塞、移动并最终筑成黄河自然堤的主要原因;巴彦木仁与磴口两地控制点对形成鄂尔多斯一侧黄河主河道起到了关键性作用;黄河西派在高湖面期间从巴彦木仁湖口注入吉兰泰-乌兰布和古湖,与从北面入湖的黄河水共同促成贺日木西尼古砂嘴及其延伸砂脊生长,并在低湖面期将这两个湖分离。基于对所述黄河历史过往的认识,须尽可能立足高效集成利用有限水资源这一观念,将减灾与适度重造沿河湖泊和绿洲结合,营建可持续的内蒙古段黄河生态体系。

淮安市古运河幸福河湖创建思考

为了探索分析幸福河湖建设经验,本文在分析淮安市古运河基本情况和特点的基础上,总结了古运河幸福河湖打造创建创新举措:管护模式创新、生态运河和文化运河创建、运河水利遗产保护与传承等。同时总结出幸福河湖建设启示:安澜之河是基本保障,以及强化水环境治理、维护河湖健康水生态、推进先进水文化建设、强化幸福河湖建设宣传引导等,以期为建设更多造福人民的幸福河湖提供借鉴。

长江-鄱阳湖顶托作用评价指标研究

长江与鄱阳湖形成的江湖交汇系统存在复杂的河床演变与物质能量交换,江湖顶托关系是影响江湖水量交换的重要因素,同时对整个区域的水资源、防洪、灌溉、航运、生态有着重要影响。以长江与鄱阳湖的交汇区为研究对象,从动量基本方程出发,建立了一套评估长江与鄱阳湖顶托强度的指标体系,提出了顶托强度指标——顶托角。研究结果表明:自20世纪80年代以来,顶托角整体上没有发生趋势性变化,说明长江对鄱阳湖的顶托作用在三峡水库蓄水后变化不明显。但从年内变化来看,在枯水期,由于三峡水库的补水作用,长江对鄱阳湖的顶托作用明显增强;在汛期,由于三峡水库的削减洪峰以及汛末蓄水,长江对鄱阳湖的顶托作用减弱。长江对鄱阳湖的顶托作用变化会在4~6月使湖水滞留湖区,易发生流域性洪水;在7~10月加速湖水的入江,使鄱阳湖的低水位形势持续恶化。研究成果可为长江和鄱阳湖的治理与保护提供参考。

不同责任半规管BPPV与主诉症状关系分析

目的分析确诊良性阵发性位置性眩晕(BPPV)患者的位置性眩晕主诉特征,以及主诉症状与BPPV责任半规管定位诊断的相关性。方法对2022年2-3月因位置性眩晕就诊于该院患者100例完成详细病史问卷调查,以视频眼震图位置试验进行BPPV客观定位诊断,分析确定诊断BPPV与病史主诉的关系。结果100例患者中以坐起-躺下、左右翻身为眩晕主要主诉者分别为39、56例,两者分辨不清5例;位置试验阳性75例,其中BPPV确定诊断63例,其他前庭周围性眩晕12例。分析63例确定诊断BPPV患者的主诉症状,以坐起-躺下眩晕确诊垂直、水平半规管BPPV的灵敏度和特异度分别为70.7%和94.4%、5.6%和29.3%,以左右翻身眩晕确诊水平、垂直半规管BPPV的灵敏度和特异度分别为94.4%和70.7%、29.3%和5.6%。进一步分析63例BPPV患者其位置性眩晕的首发体位,以坐起-躺下者确诊垂直、水平半规管BPPV的灵敏度和特异度为76.9%和55.6%、44.4%和23.1%,左右翻身者确诊水平、垂直半规管BPPV的灵敏度和特异度为55.6%和76.9%、23.1%和44.4%。对30例可明确表述眩晕诱发较重体位侧别的BPPV患者进行分析,右侧位为较重侧13例,左侧位为较重侧17例,余33例对诱发眩晕的左右侧分别描述不清。结论位置性眩晕患者的主诉症状中,“坐起-躺下”和“左右翻身”性眩晕主诉分别对垂直、水平半规管BPPV诊断的灵敏度和特异度高,符合Ewald′s定律;而首发体位及症状较重的体位侧别,对BPPV责任半规管侧别定位诊断的灵敏度和特异度均不高。位置性眩晕患者主诉症状对BPPV快速筛查具有一定的临床价值,确定定位诊断要依靠位置试验。

环鄱阳湖城市群土地利用功能转型及其驱动机制

快速城镇化背景下,推进土地利用高质量转型是实现区域可持续协同发展的重要路径。该研究基于土地利用主导功能,运用综合指数法、耦合协调度模型和时空地理加权回归模型(geographically and temporally weighted regression,GTWR)等方法,分析了环鄱阳湖城市群土地利用功能转型的时空演变特征、耦合协调水平及其驱动机制。结果表明:1)2000—2020年,环鄱阳湖城市群土地利用功能指数从0.20上升到0.55,持续优化提升,但总体上处于中低水平,土地利用功能水平表现为阶段性的变化特征;土地利用功能指数逐渐呈现出中西高、东部低的空间格局。2)生产-生活-生态功能及生产-生活功能的协调度指数持续上升,其余耦合度及协调度指数均呈波动发展的趋势,耦合协调度指数呈现中部和西南部高、东北和西北部低的空间分布格局;以低质量转型为主,平均占比约为50%,功能转型质量有所提升,中西部区县的土地利用功能转型质量要明显优于北部和东部区县。3)不同影响因子的驱动作用存在显著的空间差异。人口密度和城镇化水平的正向驱动作用持续增强,二三产业占比的负向驱动作用增强,人均GDP、人均固定资产投资和人均粮食产量的影响力趋于减弱。应根据各区县土地利用功能的转型阶段,实行差别化的发展政策,补齐区县发展短板,提升功能系统间的耦合协调度。研究结果可为提高区域用地效率,促进土地利用多功能协同发展提供参考和决策依据。