Temporal and spatial characteristics of dissolved organic carbon in the Wujiang River,Southwest China

River systems play an important role in the global carbon cycle. Rivers transport carbon to the ocean and also affect the carbon cycle in the coastal ocean. The flux from land to the ocean is thought to be a very important part of the land carbon budget. To investigate the effect of dam-building on dissolved organic carbon(DOC)in rivers, three reservoirs of different trophic states in the Wujiang basin, Guizhou Province, were sampled twice per month between May 2011 and May 2012. Temporal and spatial distributions of DOC in the reservoirs and their released waters were studied. It was found that different factors controlled DOC in river water, reservoir water, and released water. DOC in the rivers tended to be affected by primary production. For reservoirs, the main controlling factors of DOC concentration varied by trophic state. For the mesotrophic Hongjiadu Reservoir, the effect of primary production on DOC concentration was obvious. For the eutrophic Dongfengdu Reservoir and the hypereutrophic Wujiangdu Reservoir, primary production was not significant and DOC came instead from soil and plant litter.

Hydrodynamic characteristics of Wujiangdu Reservoir during the dry season-a case study of a canyon reservoir

With the development of hydropower in the karst area of Southwest China, a series of cascade canyon reservoirs have been formed through the construction of dams. Given that hydrodynamic conditions in canyon reservoirs play a pivotal role in controlling the spatiotemporal distribution of physical and chemical properties of the stored water, hydrodynamic characteristics are of great importance in understanding biogeochemical cycles in those reservoirs. To further this understanding, a field campaign was conducted in the Wujiangdu Reservoir of Guizhou Province. It was found that from the reservoir inlet to the front of the dam, velocity(v) was negativelycorrelated and had a logarithmic relationship with distance along the ship track(s) under dry-season flow conditions[v =-0.104 ln(s) + 0.4756]. Analysis showed that dryseason flow velocity had no significant correlation with water temperature, p H, or dissolved oxygen(DO). However, when velocity decreased to 0.061 m/s, water depth increased abruptly. In addition, DO displayed a sudden drop and the trend in p H changed from increasing to decreasing, while water temperature showed an opposite trend, indicating the existence of a transition zone from the river to the reservoir.

Plant opal analysis of the Guangfucun Site in Wujiang City,Jiangsu Province

The Guangfucun Site is located in thewest of Taoyuan Town,Wujiang City,the furthest south end of JiagsuProvince.It is a Neolithic site datedto 6055±125 BP.The cultural de-posits belong to the Majiabang Cul-ture.This paper reported the resultsof plant opal analysis of the site and

Optimized operation of cascade reservoirs on Wujiang River during 2009-2010 drought in southwest China

The effects of optimized operation principles implemented at reservoirs on the Wujiang River in southwest China between September 2009 and April 2010 under drought conditions were analyzed based on operational data collected from the Guizhou Wujiang Hydropower Development Co., Ltd. A set of linear regression equations was developed to identify the key factors impacting the electric power generation at reservoirs. A 59% reduction in the inflow discharge at the Hongjiadu Reservoir led to a decrease of only 38% in the total electric power generation at the Hongjiadu, Dongfeng, Suofengying, and Wujiangdu reservoirs on the Wujiang River, indicating that optimized operation can play an important role in drought management. The water level and the amount of other water inputs at the Hongjiadu Reservoir and the outflow discharge at all of the reservoirs except the Wujiangdu Reservoir were key factors affecting the total electric power generation at reservoirs on the Wujiang River under optimized operation.

Scale effects of eroded sediment transport in Wujiang River Basin, Guizhou Province, China

In recent years, research on spatial scale and scale transformation of eroded sediment transport has become a forefront field in current soil erosion research, but there are very few studies on the scale effect problem in Karst regions of China. Here we quantitatively extracted five main factors influencing soil erosion, namely rainfall erosivity, soil erodibility, vegetative cover and management, soil and water conservation, and slope length and steepness. Regression relations were built between these factors and also the sediment transport modulus and drainage area, so as to initially analyze and discuss scale effects on sediment transport in the Wujiang River Basin(WRB). The size and extent of soil erosion influencing factors in the WRB were gauged from: Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM), precipitation data, land use, soil type and Normalized Difference Vegetation Index(NDVI) data from Global Inventory Modeling and Mapping Studies(GIMMS) or Advanced Very High Resolution Radiometer(AVHRR), and observed data from hydrometric stations. We find that scaling effects exist between the sediment transport modulus and the drainage area. Scaling effects are expressed after logarithmic transformation by a quadratic function regression relationship where the sediment transport modulus increases before decreasing, alongside changes in the drainage area. Among the five factors influencing soil erosion, slope length and steepness increases first and then decreases, alongside changes in the drainage area, and are the main factors determining the relationship between sediment transport modulus and drainage area. To eliminate the influence of scale effects on our results, we mapped the sediment yield modulus of the entire WRB, adopting a 1 000 km^2 standard area with a smaller fitting error for all sub-basins, and using the common Kriging interpolation method.

A preliminary study on the distribution characteristics of nutrients (N, P, Si, C) in the Wujiang River Basin

The distribution of nutrients (N, P, Si, C) in the Wujiang River surface water was studied during the high-flow and low-flow periods in 2002. The results showed that nitrate nitrogen (NO-3-N) is the main form of dissolved inorganic nitrogen (DIN) in the Wujiang River Basin. It accounts for about 90% of DIN. The average NO-3-N concentrations in the mainstream are {147.5} μM in the high-flow period and {158.0} μM in the low-flow period, respectively. The average concentrations of total phosphorus (TP) are {6.43} μM in the high-flow period and {4.18} μM in the low-flow period, respectively. Of the various forms of phosphorus, particulate phosphorus (PP) has the highest percentage ({62.9%}) of TP in the high-flow period. In the low-flow period, however, phosphate is the main form of phosphorus, which accounts for 49% of TP. With the Wujiangdu Reservoir as the boundary, the concentrations of DIN and phosphorus in the upper reaches are different from those in the lower reaches of the Wujiang River. As a whole, the concentrations of DIN and phosphorus are both higher in the low-flow period than in the high-flow period. The spatial and temporal variations of DIN and phosphorus concentrations suggested that DIN and phosphorus come from agricultural and domestic wastewaters and groundwaters and that the Wujiangdu Reservoir has an important impact on the concentrations and distribution of DIN and phosphorus in the Wujiang River. The distribution patterns of dissolved silica (DSi) and dissolved organic carbon (DOC) are similar. Both of them maintain no change in the whole course of the river and their concentrations (with the exception of the reservoir itself) are higher in the high-flow period than in the low-flow period. The average DSi and DOC concentrations in the mainstream are {85.4}, {84.6} μM in the high-flow period and {60.8}, {53.9} μM in the low-flow period, respectively. The concentrations of nutrients in most of the major tributaries are lower than in the mainstream. This suggested that the contributions of most tributaries are relatively small but importance should be attached to the influence of some individual tributaries such as the Qingshuijiang River and the Weng’an River on the mainstream.

贵州北部乌江光唇鱼属一新种——芙蓉江光唇鱼

报道了2020年10月在贵州北部乌江流域芙蓉江支流芙蓉江水系采集到的鲤科Cyprinidae鱼类样本,经鉴别为光唇鱼属Acrossocheilus一新种,命名为芙蓉江光唇鱼A. furongjiangensis sp. nov.。新种体细长而侧扁,尾柄细;头短小;须2对。肠道有4道弯曲。背鳍起点位于吻端至尾鳍基中点或略偏后;胸鳍末端伸达胸鳍起点至腹鳍起点中部或稍后;腹鳍起点与背鳍起点几乎相对;臀鳍起点位于腹鳍和尾鳍基的中点;尾鳍叉形。侧线完全。背鳍ⅲ-8;胸鳍ⅱ-15;腹鳍ⅲ-8;臀鳍ⅲ-5。该新种与云南光唇鱼A. yunnanensis外形相似,但新种躯体更细长、头更短、尾柄更细长、眼更大、两眼更靠近。新种背鳍末根不分枝鳍条为粗壮硬刺,后缘有17~20个锐利锯齿。鳔后室长超过前室长的2倍,前室椭圆前端有凹陷。体色自幼鱼至成鱼体侧均无不规则黑色斑点。上颌须长,向后延伸超过眼外缘。眼中点水平延伸线与鳃盖外缘近中部相接。新种与分布于贵州水域的同属种如吉首光唇鱼A. jishouensis、虹彩光唇鱼A. iridescens在体高、头长、头高、尾柄高和眼径上的差异均极显著(P<0.01)。

基于MSPA与电路理论的水网地区生态网络构建

快速城镇化背景下,城镇化扩张导致水网区域生境斑块日益破碎化和孤岛化,科学构建水网地区生态网络是有效连接生境斑块的重要手段,对保障区域生态系统连通性和稳定性具有关键意义。文中以苏州市吴江区为例,运用MSPA与景观连通性评价综合识别生态源地,基于MCR模型叠加多因子构建综合阻力面,利用电路理论提取生态廊道和节点,依据"生态源地识别—综合阻力面构建—生态廊道提取—生态节点选取"模式构建吴江区生态网络体系。结果表明:研究区内识别重要生态源地与一般生态源地共30个,总面积196.73 km^(2),景观构成要素以湖泊、湿地等用地类型为主;最优生态廊道42条,平均长度6.53 km,潜在生态廊道27条,平均长度4.28 km,但廊道空间分布不均匀,密度呈现由东北向西南逐渐降低的态势;通过保护与修复17处生态夹点和26处生态障碍点,有效提升区域景观连通性,增强生态网络稳定性。基于研究结果,提出加强生态源地保护、提高生态廊道连通性、优化与修复生态节点的生态网络优化策略,以期促进水网地区生态环境保护与生境质量提升。

The Ecological Importance and Influence of Land Use on Carbonic Anhydrase Activity of Waters in the Upstream Section of the Wujiang River Basin

Thirty-four sampling sites for surface water and twenty-seven sampling sites for ground water in areas of different land use were selected in the Wujiang River Basin, upstream section in Guizhou Province, China. Carbonic anhydrase （CA） activity in surface and ground water was analyzed and compared. The results show that CA activity was detected in all surface and ground water samples. In general, average CA activity in surface and ground water was highest from samples in arbor lands, followed by shrub lands, shrub and grass lands, agricultural lands, and residential areas. The average CA activity in ground water from arbor lands, shrub lands, and shrub and grass lands was higher than that in surface water. Water CA activity was positively correlated with HCO3- concentration in surface water and ground water. These results imply that the contribution of CA in water to the karst carbon sink potential of river basins warrants further extensive and in-depth research.

乌江下游梯级水库浮游植物群落结构特征与多样性分析

2021年9月,结合水文情势、生物分布特征及生境等实际情况,设置8个监测断面,调查乌江下游彭水和银盘2个梯级水电站影响区域内的浮游植物落结构特征及多样性,探讨乌江下游梯级电站对浮游植物群落结构的影响。本次调查采集到浮游植物6门37属51种,硅藻门占浮游植物总种类数的60.8%,浮游植物平均密度为4.1×106cells/L,平均生物量为0.792 mg/L。Shannon-Wiener多样性指数范围为1.63~2.84,Margalef丰富度指数范围为3.08~5.41。乌江下游银盘和彭水电站影响区域主要以硅藻门为主,浮游植物群落空间分布差异较大,库尾及以上急流区域的浮游植物多样性指数比库区缓流段高。Shannon-Wiener多样性指数和Margalef丰富度指数分析表明,蓄水后适应流水环境的浮游植物种类数变少。与蓄水前对比发现,蓄水后浮游植物种类数和生物多样性均有所降低,梯级电站建设在一定程度上降低了库区浮游植物的多样性。

乌江磷浓度与通量变化及来源解析

磷(P)是长江流域备受关注的污染物。乌江是长江八大支流之一,位于三峡水库近库尾江段。武隆断面是乌江入长江控制断面。对1998-2019时期武隆断面径流量、悬浮泥沙浓度(SS)与输沙量、磷浓度与通量(包括总磷(TP)、溶解态磷(DP)和颗粒态磷(PP))年际变化及季节特征进行研究,并基于河流基流分割原理对磷的来源进行了解析。结果表明,(1)1998-2019年,乌江武隆断面径流量在一定幅度内上下波动,而悬浮泥沙浓度和输沙量下降剧烈。(2)22年来,乌江TP和DP浓度与通量总体上呈先升高后下降的趋势,2009-2013年为磷污染峰值期,TP和DP浓度与通量远高于其它时期。(3)2007年是一个重要的时间节点,该节点前,TP的赋存形态以颗粒态为主,颗粒态磷在总磷中的占比均值为65%;该节点后,TP的赋存形态转变为以溶解态为主,颗粒态磷占比均值下降为16%,相应地,溶解态磷占比由35%上升为84%。水沙条件改变是磷形态发生显著变化的主要驱动力,磷污染程度亦是磷形态变化的重要影响因素。(4)磷通量在年内的季节分布发生了显著变化,丰水期磷通量减少,枯水期磷通量增加。(5)1998-2012、2009-2013和2014-2019年3个时期点源负荷占比分别为23.5%、36.8%和62.1%,呈增加趋势。(6)建议制定适宜的总磷控制目标,结合目前所存在的磷污染风险点,进一步强化监管,侧重源头治理。

水电水库水力负荷对生源要素同化效率的调控作用

河流筑坝发电是目前最为显著的人为扰动河流事件,形成的水电水库阻断了河流连续体,改变了其中生源要素的生物地球化学循环过程,但相关的影响机制还不完全清楚。为此,本研究以乌江11座水电水库为研究对象,季节性调查了水库及相应河流的生源要素(CO_(2)、溶解态无机氮DIN、溶解态无机磷DIP和溶解态硅DSi)浓度及相关的理化因子,以了解河流水库化过程中生源要素浓度的变化过程及水动力条件的变化对其生物地球化学循环的影响机制。结果表明,河流区CO_(2)、DIN、DIP和DSi浓度均高于水库区,水库区内各理化因子间的关联度显著高于河流区。研究水库对各种生源要素的同化效率表现出显著的时空差异;其中对CO_(2)和DSi的同化效率最高,季度均值分别为50%和40%。库区中各生源要素的同化效率和分层强度均与水力负荷显著负相关,表明水电水库的水动力条件是调控其生物地球化学循环强度的关键因素;滞留时间较长和较深的水电水库有利于浮游植物同化生源要素和促进其在剖面上的季节性分层。研究将加深对筑坝河流元素生物地球化学循环过程的认识,有助于水电水库管理措施的制定。

乌江流域梯级水库群混合期N_(2)O的释放机理及其影响因素

筑坝显著改变了河流生源要素的生物地球化学循环过程,尤其是对氮循环和温室气体N_(2)O产生和释放的影响,已逐渐受到广泛的关注。本文以乌江中上游4个梯级水库为研究对象,通过分析其冬季混合期的溶存N_(2)O和氮形态含量,探讨混合期亚热带深水型水库N_(2)O的产生机理和影响机制,并对水库N_(2)O释放通量进行估算。结果表明,洪家渡、东风、索风营和乌江渡水库水体溶存N_(2)O浓度均处于过饱和状态,表现为N_(2)O的释放源;其释放通量均值分别为:(0.48±0.07)、(0.34±0.04)0.35和(0.91±0.76)μmol/(m^(2)·h),与全球其它湖泊/河流系统相比处于中等水平。本研究发现水库混合期水体N_(2)O主要来自于硝化作用,其中处于富营养状态的乌江渡水库的深层水体可能受到硝化-反硝化耦合作用及反硝化作用的影响,由此产生的高含量N_(2)O通过底层泄水途径成为重要的释放源。综合考虑各水库特征,水库N_(2)O的产生还受到水库调节类型和库龄的间接影响。对比发现使用IPCC对河流-水库系统N_(2)O间接释放系数的估算可能会显著高估乌江中上游梯级水库群释放潜力。研究结果为未来评估梯级水库群N_(2)O排放水平和梯级开发背景下流域氮的时空格局变化提供了重要的研究参考。

虹垂千载,风雅江南:吴江垂虹桥风景营造探析

吴江垂虹桥是我国传统桥梁式风景营造的典范。其历经千载,融自然风光与人文胜迹于一体,是“雄冠一邑”、“声满东南”的天下绝景。从风景园林学视角,以垂虹桥风景地为研究对象,通过史料考证、调研实测等研究方法,探索东太湖水陆变迁背景下垂虹桥风景营建的历史沿革。并在此基础上,从相地、布局、构桥和理微四个层面分析垂虹桥风景理法的特征。从而进一步透过景观意向,从区域风景体系构建、精神品格空间表达、艺术创作与文人活动和清代皇家园林写仿四个方面,提炼垂虹桥风景地蕴含的风雅文化内涵。为垂虹桥风景遗产的保护和传承提供借鉴。

基于VORC模型的水网乡村生态系统健康评价及管控策略——以吴江区为例

健康的生态系统能够维持生态活力及组织力,抵御和适应外界压力,发挥生态系统服务功能。文章以苏州市吴江区为例,基于“活力(V)—组织力(O)—恢复力(R)—贡献力(C)”模型,定量评价水网乡村生态系统健康水平,分析生态系统健康空间分异特征,为生态空间分区管控提供科学依据。研究结果表明:吴江区生态系统健康综合指数在空间分布上呈正相关性,表现出“高值区较离散,低值区较集聚”的特征。健康高值区多聚集于乡村水网密布区域,生态环境质量较好,生态功能较完善;健康低值区主要集中于乡村工业产业建设集聚区域,受建设用地扩张影响,水网乡村景观生态健康水平下降。结合健康等级将吴江区划分为核心保护区、生态缓冲区、协调发展区和开发管控区等4类空间管控分区,并针对性地提出差异化管控策略。生态系统健康评价可为生态空间分区管控提供依据和参考,促进水网乡村生态系统持续、健康发展。

浅谈山区钢桁梁悬索桥智能建造施工技术

依托贵阳经金沙至古蔺高速公路控制性工程金烽乌江大桥,对施工过程中采用的数字化建造技术、钢桁梁虚拟拼装技术等要点进行探讨,同时总结施工过程中项目重难点解决措施、项目管理创新点等,确保项目又好又快地完成目标任务。

贵州乌江流域人口收缩的时空格局演变及影响因素

以贵州乌江流域为研究对象,基于2000、2010、2020年3期人口普查数据以及2005年和2015年常住人口数据,探析贵州乌江流域县域人口收缩的时空格局演变,并探究其成因。结果表明:(1)贵州乌江流域人口收缩现象较为明显,2000—2010年和2010—2020年人口收缩县域分布较广,占比均超过50%。(2)研究期内人口持续收缩是主要特征,集中于下游地区,但分布范围逐渐缩小,中游地区人口变动剧烈。(3)基于收缩程度,研究期内以人口中度收缩为主,不同时期人口收缩程度起伏较大,随时间推移人口收缩程度有减弱趋势。(4)随时间演化人口自然增长因素对人口收缩演变影响减弱,人均生产总值、非农就业水平等经济发展因素影响力逐渐增强。