Spatial and temporal variations of water quality in Cao-E River of eastern China

Evaluation and analysis of water quality variations were performed with integrated consideration of water quality parameters, hydrological-meteorologic and anthropogenic factors in Cao-E River, Zhejiang Province of China. Cao-E River system has been polluted and the water quality of some reaches are inferior to Grade V according to National Surface Water Quality Standard of China （GB2002）. However, mainly polluted indices of each tributary and mainstream are different. Total nitrogen （TN） and total phosphorus （TP） in the water are the main polluted indices for mainstream that varies from 1.52 to 45.85 mg/L and 0.02 to 4.02 mg/L, respectively. TN is the main polluted indices for Sub-watershed Ⅰ, Ⅱ, Ⅳ and Ⅴ（0.76 to 18.27 mg/L）. BOD5 （0.36 to 289.5 mg/L）, CODMn （0.47 to 78.86 mg/L）, TN （0.74 to 31.09 mg/L） and TP （0 to 3.75 mg/L） are the main polluted indices for Sub-watershed Ⅲ. There are tow pollution types along the river including nonpoint source pollution and point source pollution types. Remarkably temporal variations with a few spatial variations occur in nonpoint pollution type reaches （including mainstream, Sub-watershed Ⅰ and Ⅱ） that mainly drained by arable field and/or dispersive rural dwelling district, and the maximum pollutant concentration appears in flooding seasons. It implied that the runoff increases the pollutant concentration of the water in the nonpoint pollution type reaches. On the other hand, remarkably spatial variations occur in the point pollution type reaches （include Sub-watershed Ⅲ, Ⅳ and Ⅴ） and the maximum pollutant concentration appears in urban reaches. The runoff always decreases the pollutant concentration of the river water in the seriously polluted reaches that drained by industrial point sewage. But for the point pollution reaches resulted from centralized town domestic sewage pipeline and from frequent shipping and digging sands, rainfall always increased the concentration of pollutant （TN） in the river water too. Pollution controls were respectively suggested for these tow types according to different pollution causes.

Relationship between catchment characteristics and nitrogen forms in Cao-E River Basin, Eastern China

The distribution of different nitrogen forms and their spatial and temporal variations in different pollution types of tributaries or reaches were investigated. Based on the catchments characteristics the tributaries or reaches can be classified into 4 types, including headwater in mountainous areas （type Ⅰ）, agricultural non-point source （NPS） pollution in rural areas （type Ⅱ）, municipal and industrial pollution in urban areas （type Ⅲ）, and combined pollution in main stream （type IV）. Water samples were collected monthly from July 2003 to June 2006 in the Cao-E River Basin in Zhejiang, eastern China. The concentrations of NO3^--N, NH4^＋ -N, and total nitrogen （TN） were measured. The mean concentrations of NO3^- -N were decreased in the sequence type IV 〉 type Ⅱ〉 type Ⅲ 〉 type Ⅰ, whereas, NH4^＋-N, total organic nitrogen （TON）, and TN were in the sequence： type Ⅲ〉 type Ⅳ 〉 type Ⅱ〉 type Ⅰ. In headwater and rural reaches, CNO^-2-N was much higher than Crea^＋ 4-N. In urban reaches, TON and NH4^＋ -N were the main forms, accounting for 54.7% and 32.1% of TN, respectively. In the whole river system, Crea^＋ 4--N decreased with increasing distance from cities, and CNo^-3 -N increased with the increasing area of farmland in the catchments. With increased river flow, CNO^-3 N increased and Crea4^＋-N decreased in all types of reaches, while the variations of CTON and CTN were different. For TN, the concentration may be decreased with the increase of river flow, but the export load always increased.

Carbon isotopes and lignin phenols for tracing the floods during the past 70 years in the middle reach of the Changjiang River

The Lake Tian E Zhou(TEZ,an oxbow lake)was formed during the rerouting of the Changjiang River in 1972,with strong influences from the main river channel and flood events.Herein,a sediment core was collected from the Lake TEZ for the measurements of carbon isotopes and biomarkers,including stable carbon isotopes(δ13C),radiocarbon composition(?14C),and lignin phenols,as well as lead-210 to reconstruct recent heavy flood events over the past 70 years.At the 24–26 cm interval,the sediment contained the highest OC%,TN%,and lignin phenols content,as well as significantly depleted 13C but enriched 14C,corresponding to the extreme flood event in 1998.In addition,statistics from t-test showed that lignin phenols normalized to OC(Λ8),the concentration of 3,5-dihydroxy benzoic acid(3,5-BD),and the ratio of p-hydroxy benzophenone to total hydroxyl phenols(PHB/HP)were all significantly different between the layers containing flood deposits and the layers deposited under normal non-flood conditions(p<0.05).These results indicate that the later three parameters are highly related to flood events and can be used as compelling proxies,along with sediment chronology,for hydrological changes and storm/flood events in the river basin and coastal marine environments.

Numerical modeling of flow in continuous bends from Daliushu to Shapotou in Yellow River

The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group （RNG） k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-e model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning＇s roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases.

Microbial Assay of Otamiri River and Its Sediments in Parts of Owerri

The aim of the study was to analyse and identify microbial constituents in the water and sediment samples with comparison of the River to World Health Organisation (WHO, 2011) standard for drinking water and Federal Ministry of Environment (FME, 2006) and their public health implications with respect to water quality. The microbial assay of Otamiri River was investigated using Standard plate count. The result indicates that microbial constituents of Otamiri river obtained at five strategic gauge stations designated SSWS1 (Egbu), SSWS2 (Timber Market), SSWS3 (FUTO), DOWNSTREAM (Mbirichi) and CONTROL POINT with mean Total coliform Count of 3.0 × 102, 3.0 × 103, 4.1 × 103 and 1.0 × 103 cfu/100ml with control point value of 0.5 × 103 respectively. The mean Total Bacteria Count was 3.0 × 104, 2.1 × 103, 1.1 × 103 and 0.8 × 103 cfu/100ml respectively with control point value of 0.2 × 103 while the mean values for Total E. coli Count were 1.1 × 102, 3.0 × 102, 4 × 103 and 2.0 × 103 cfu/100ml with control point value of 0.2 × 103. The biochemical identification of some organisms in water was Escherichia coli, Vibro spp., Klebsiella spp., and Entrobacteria spp. The result of stream sediment samples indicates that the mean Total Bacterial Count was 3.5 × 104, 5.0 × 104, 6.5 × 104 and 2.0 × 104 cfu/g respectively with 1.5 × 102 as control point value and that of Total Coliform Count was 6.5 × 103, 2.0 × 103, 2.5 × 103 and 0.8 × 103 cfu/g respectively with control point value of 0.5 × 102. While for the Total E. coli Count, the values were 2.5 × 103, 1.0 × 103, 2.5 × 103 and 0.5 × 105 cfu/g respective with control as 0.5 × 102. Biochemical identification of some organisms in sediments includes: Escherichia coli, Vibro spp., Klebsiella spp., Entrobacteria spp. and Bacillus spp. The mean total bacterial count, total coli form count and total E. coli, were not in conformity with both World Health Organisation (WHO, 2011) Standard for drinking water and Federal Ministry of Environment (FME) 2006 standard for soil and thus constitute a threat to the River;these are attributed to waste dumps and anthropogenic activities around the five stations. The presence of bacteria in water can cause cholera, hepatitis, dysentery and typhoid. The microbial constituents can be reduced by chlorination.

Antimicrobial Susceptibility Profiles among <i>Escherichia coli</i>Strains Isolated from Athi River Water in Machakos County, Kenya

Antimicrobial use in agriculture, livestock and human health has increased over the years leading to the increase in antimicrobial resistance that can also find its way to the aquatic environment. Rivers can act as reservoirs of highly resistant strains and facilitate the dissemination of multidrug resistant (MDR) strains to animals and humans using water. A total of 318 water samples were collected from six different sampling points along Athi River and E. coli isolates were subjected to Kirby-Bauer diffusion method for antimicrobial susceptibility testing. The total mean coliform count of the sampled sites was 2.7 × 104 (cfu/mL). E. coli isolates were most resistant to ampicillin (63.8%) and most susceptible to gentamicin (99.4%). MDR strains (resistance to ≥3 classes of antibiotics) accounted for 65.4% of all the isolates. The site recorded to have human industrial and agricultural zone activities had strains that were significantly more resistant to ampicillin, cefoxitin, amoxicillin/clavulanic acid (P ≤ 0.05) than isolates from the section of the river traversing virgin land and land with minimum human activities. This study indicates that E. coli strains isolated from Athi River were highly MDR and most resistant to some antimicrobial classes (ampicillin and cefoxitin) which constitute a potential risk to human and animal health.

<i>Escherichia coli</i>Harbouring Resistance Genes, Virulence Genes and Integron 1 Isolated from Athi River in Kenya

Rivers can act as reservoirs of highly resistant strains and facilitate the dissemination of resistance, virulence and integron 1 genes. A cross-sectional study was carried out where 318 water samples were collected (53 from each site) and from the samples, 318 E. coli isolates were analysed for resistance genes, virulence genes and integron 1 using Polymerase Chain Reaction. 22% of the isolates had blaTEM, 33% had blaCTX-M and 28% had blaCMY. Prevalence of typical Enteropathogenic E. coli strains (carrying both eae and bfp genes) was 5% while the prevalence of atypical Enteropathogenic E. coli (carying only eae) was 1.8%. The prevalence of Enteroaggregative E. coli carrying the aggr genes was 11%. The prevalence of Enterotoxigenic E. coli encoding only lt toxin was 16 (5%) and while those carrying only st toxin was 6.9%. The prevalence of Enteroinvasive E. coli strains encoding as IpaH was 5% while that of strains, adherent invasive E. coli, carrying adherent invasive gene inv was 8.7%. 36% isolates were positive for class 1 integrons which were mostly isolated near the sewage effluent from waste treatment plant. Anthropogenic activities and close proximity to sewage treatment plant were found to play a key role in pollution of water body and accumulation of resistance and virulence genes. These results suggest that waste treatment plant may act as reservoir of resistance, virulence and integron 1 genes and is a potential risk to human and animal health in the region.

An evaluation of soil moisture from AMSR-E over source area of the Yellow River, China

In this study,in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture prod ucts from NASA(National Aeronautics and Space Administration),JAXA(Japanese Aerospace Exploration Agency)and VUA(Vrije University Amsterdam and NASA)over Maqu County,Source Area of the Yellow River(SAYR),China.Re sults show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area,with a minimum RMSE(root mean square error)of 0.08(0.10)m3/m3 and smallest absolute error of 0.07(0.08)m3/m3 at the grassland area with ascending(descending)data.Therefore,the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR.The VUA soil moisture product shows that soil moisture presents a declining trend from east south(0.42 m3/m3)to west north(0.23 m3/m3),with good agreement with a general precipitation distribution.The center of SAYR presents extreme wetness(0.60 m3/m3)dur ing the whole study period,especially in July,while the head of SAYR presents a high level soil moisture(0.23 m3/m3)in July,August and September.

Application of equivalent resistance to simplification of Sutong Bridge piers in tidal river section modeling

This paper describes some details and procedural steps in the equivalent resistance （E-R） method for simplifying the pier group of the Sutong Bridge, which is located on the tidal reach of the lower Yangtze River, in Jiangsu Province. Using a two-dimensional tidal current numerical model, three different models were established： the non-bridge pier model, original bridge pier model, and simplified bridge pier model. The difference in hydrodynamic parameters, including water level, velocity, and diversion ratio, as well as time efficiency between these three models is discussed in detail. The results show that simplifying the pier group using the E-R method influences the water level and velocity near the piers, but has no influence on the diversion ratio of each cross-section of the Xuliujing reach located in the lower Yangtze River. Furthermore, the simplified bridge pier model takes half the calculation time that the original bridge pier model needs. Thus, it is concluded that the E-R method can be use to simplify bridge piers in tidal river section modeling reasonably and efficiently.

黄河流域水-能源-粮食纽带系统效率研究

为了促进黄河流域高质量发展,考察黄河流域水-能源-粮食(W-E-F)纽带系统效率及其影响因素,并从中探寻提高系统效率的途径。首先借助三阶段DEA模型测算2005—2021年黄河流域及各省(区)W-E-F纽带系统效率,其次对黄河流域整体及各省(区)效率测算结果进行时空分析,最后使用双向固定效应模型实证考察W-E-F纽带系统效率的影响因素。研究表明:1)黄河流域整体W-E-F纽带系统效率呈现波动上升趋势,并呈现上、中、下游效率依次上升的空间分布格局;2)黄河流域各省(区)具备一定的资源配置能力,第三阶段规模效率有所下降;3)粮食安全、能源安全、环保支出、研发投入以及人均GDP都对W-E-F纽带系统效率起到显著的正向促进作用。

曹娥江适宜生态流量计算和评价研究

保障河流生态流量对维持河流生态健康状态具有重要意义。通过对曹娥江流域东沙埠和黄泥桥两个控制断面1961—2017年还原径流量资料进行可靠性、代表性和一致性检验,表明还原径流量可视为天然径流量。选取Tennant法、Qp法、频率曲线法、年内展布法、月流量变动法共5种水文学方法分别计算两个控制断面各月适宜生态流量。以准确率、满足率和适宜度为指标综合评价了不同方法在曹娥江流域研究区的适用性,最终推荐月流量变动法作为适宜生态流量的计算方法,最小值分别为14.83 m^(3)/s和2.44 m^(3)/s,最大值分别为46.61 m^(3)/s和6.74 m^(3)/s。该研究为流域水库生态调度提供参考。

长三角城市群农产品电商发展水平时空演化及影响因素

基于2016—2020年长三角城市群25个城市(未含上海市)的面板数据,采用熵值法、莫兰指数与回归分析等多元统计方法,深入探究该地区农产品电商发展的时空分布格局及其关键影响因素。研究发现:长三角城市群农产品电商发展水平在空间上呈现出明显的正向相关性,并显示出集聚特征,但近年来这种集聚效应呈现出减弱的趋势,显示出集中与扩散的双重特征;长三角城市群农产品电商发展存在区域不平衡性,高、中高发展水平层次城市主要集中在沿海和东南部地区;长三角城市群农产品电商的发展受到多重因素的影响,包括经济环境、产业结构、农业现代化、物流体系以及信息技术等。因此,应加强长三角城市群内部的农产品电商协同发展,引导优化和共享电商资源,降低运营成本并提升市场竞争力;优化长三角城市群农产品电商的空间布局,采取差异化的区域发展策略,推动城市群内部的产业梯度转移和合作,促进均衡发展;构建长三角城市群农产品电商发展的多维支撑体系,涵盖经济支持、产业融合与转型以及物流和信息技术的投入创新。

基于AMSR-E的黄河源区表层土壤水分时空变化（英文）

黄河源区生态环境和水文过程对气候变化的响应是该区域研究的热点问题,但相对于其他环境和水文要素而言,大尺度长序列的土壤水分时空分布特征研究不足。本文基于AMSR-E被动微波遥感数据和地面实测数据,首先采用引入Qp模型的双通道反演算法校正AMSR-E土壤水分数据,获得的土壤水分产品(SMD)精度高于官方提供的土壤水分产品(SMO),但其波动范围与实测数据有差异。之后采用逐月回归分析法对SMD进行二次校正,其土壤水分产品(SML)具有更高的精度且变化趋势与实测数据一致。基于SML土壤水分产品,对黄河源区及其5个自然分区表层土壤水分的时空变化特征及其影响因素进行分析。黄河源区年平均表层土壤水分为0.140~0.380 cm3/cm3,在2003—2010年间呈下降趋势,在东南部土壤水分较高的若尔盖丘状高原区、黄南山地区和果洛玉树高原宽谷区土壤水分呈下降趋势,其中若尔盖丘状高原区的下降速率最快,而在西北部土壤水分较低的黄河源宽谷湖盆区和柴达木东缘山区呈增加趋势;春季土壤水分呈下降趋势,夏季呈增加趋势,秋季的波动较大,冬季的变化的不大,其中9月土壤水分增加率和5月减少率最大。土壤水分受降水和植被指数的影响最大,气温表现为在年高温月份与土壤水分呈负相关,在年低温月份呈正相关。研究结果为AMSR-E土壤水分数据的研究与应用提供了依据,有助于深化对区域尺度土壤水分格局及其对气候变化响应的研究,对高原生态环境建设有重大意义。

基于大数据的黄河流域O2O电子商务空间演化研究

近年来,以网络团购为代表的平台经济蓬勃发展,对城市商业空间产生重大影响,其空间演化规律引起学界广泛关注。利用网络爬虫技术采集我国最大O2O电商平台—美团点评的商家评论大数据,采用GIS分析和数理统计方法对黄河流域O2O电商空间演化过程进行系统分析,得出结论如下:黄河流域O2O电商发展具有明显阶段性,2012~2014年为缓慢发展期,2015~2016年为疯狂扩张期,2017~2019年为稳定增长期,2020年后进入剧烈波动期;黄河流域O2O电商空间发展格局具有明显层级性,郑州和西安居第一层级,青岛、济南、洛阳等6个城市居第二层级,太原、呼和浩特、兰州等17个城市居第三层级,银川、西宁等22个城市居第四层级,其他38个城市居第五层级;黄河流域O2O电商空间扩张具有明显的等级扩散和传染扩散相复合的特征;黄河流域O2O电商发展呈现愈发明显的“极化”现象。研究结论对于推动黄河流域数字技术与实体经济的深度融合、培育壮大新经济、实现高质量发展、具有一定参考价值。

电子商务发展能否促进地区人口增长?——基于长三角人口普查与B2B电商企业数据的相关性研究

本文基于第六、七次人口普查数据与B2B电商企业数据,研究长三角区县(市)尺度的人口变化特征和电商发展水平,并对电商企业数量与人口变化进行相关性分析,探究电子商务发展与地区人口增长的关系。研究发现电商发展能够影响地区人口流动趋势,有效促进地区人口增长,但作用效果存在明显的区域差异。电商发展的人口拉动效果最为明显的空间单元,通常为具有一定经济发展基础但尚不发达的地区,在江浙两省是县(市),而在安徽省是市辖区。

长江经济带农村电商直播发展现状与优化路径

互联网高速发达的今天,农产品销售方式发生了翻天覆地变化,农村电商直播开始出现在大众视野。本研究以农村电商直播为视角,运用SWOT方法从优势、劣势、机遇和挑战4个方面对长江经济带农村电商直播行业进行内外环境定性分析。研究发现当前农村电商直播在基础设施、地理区位、“互联网+”时代和消费需求提质等方面拥有优势与机遇,在电商直播专业人才、品牌建设、产品质量和电商直播效果等方面存在劣势与挑战。最后,结合现状针对性地提出了延展型战略、扭转型战略、防卫型战略和多元型战略4种推动长江经济带农村电商直播良性发展的战略建议。

黄河水中固体粒子与Cu、Pb、Zn、Cd相互作用的离子交换率E(%)-pH曲线的研究

采用离子交换法和原子吸收分光光度法研究了黄河游水体中固体粒子(表层沉积物〕与铅、铜、锌、镉液-固界面的相互作用,及各种环境因素对颗粒表面吸附作用的影响,绘制了离子交换率E(％)-pH曲线。实验结果为:1)铜、铅、锌、镉均以一价络离子形式在固体粒子表面进行阳离子交换反应;2)pH值是控制金属离子向固相迁移的主要因素,且E(％)随pH升高而增大。在天然黄河水pH范围(8.0-8.5)内,四种金属离子的E(％)可达80-100％;3)E(％)-pH曲线会随金属离子浓度的增高而向高pH方向移动,表明E(％)下降;4)随固体粒子浓度增大,E(％)就会增高,使E(％)-pH曲线向小pN方向移动;5)固体粒子的粒度增大也会使离子交换率下降;6)加入一定浓度的甘氨酸会使镉离子交换率E(％〕增大。

ZrO_2对CaO-SiO_2系玻璃析晶的影响

通过DSC曲线研究了不同含量的ZrO2对CaO-SiO2系玻璃析晶的影响,根据JMA方程计算动力学参数(如析晶活化能E、频率因子ν、晶化指数n)。从计算结果可以看出,随着ZrO2含量的增加,析晶活化能E减少,而频率因子ν和晶化指数n增加。当ZrO2含量为7%时,E值最小:235.58kJ/mol;n值最大:4.70。说明ZrO2在CaO-SiO2玻璃体系是有效的晶核剂。

长江经济带电子商务发展水平的动态演进

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