A comparison of zooplankton assemblages in Nansi Lake and Hongze Lake,potential influences of the East Route of the South-to-North Water Transfer Project,China

Nansi Lake and Hongze Lake are both water storage lakes along the East Route of the South-to-North Water Transfer project(ESNT).Frequent changes in hydrologic properties are responsible factors for controlling the zooplankton community assemblages in both lakes,so we studied the possible influence of water transfer and environmental factors on zooplankton community structure and abundance.Zooplankton assemblages were investigated seasonally for one year in both lakes;a total of 133 and 122 zooplankton taxa were identified in Nansi Lake and Hongze Lake,respectively.The most dominant rotifer species were littoral,e.g.,Keratella tecta,Keratella valga and Lecane lunaris in Nansi Lake and Brachionus angularis,Brachionus forficula and Polyarthra vulgaris in Hongze Lake.Comparatively,Nansi Lake had a higher Shannon-Wiener diversity index value(5.13),while Hongze Lake had a higher species richness index(4.21).The average number of zooplankton across seasons in Nansi Lake(protozoa:774±63 ind./L,rotifers:4817±212 ind./L,cladocerans:896±14 ind./L,copepod:435±42 ind./L)was comparatively lower than Hongze Lake(protozoa:1238±63 ind./L,rotifers:6576±112 ind./L,cladocerans:1013±20 ind./L,copepod:534±25 ind./L).Canonical correspondence analysis identified differing environmental gradients that were most responsible for influencing zooplankton communities in the two lakes(Hongze Lake:NH4-N,total nitrogen,transparency and pH;Nansi:pH,temperature and total phosphorus).Frequent changes related to water transfer in lakes favoured the diversity of rotifers and protozoa communities.Zooplankton habitat preference,changes in community structure and opportunistic peaks and extinction of certain taxa were also observed in the study lakes.

The Construction and Study of Nansi Lake Water Environment Management Platform Based on WebGIS

According to targets and needs of Nansi Lake water eco-environment management, we took the advantages that WebGIS serves as an overall solution, combined characteristic of SuperMap IS.net WebGIS service platform and adopted the B/S three-tier distributed architecture to put forward the overall design idea, function structure and structure scheme of Nansihu water eco-environment assessment and management WebGIS. Subsequently, we used the C# programming language to carry out the concrete development job, and figured out a scheme to store and disseminate space data and attributes data. Ultimately, with the aid of SuperMap’s large-scale spatial database engine SDX+, the system has realized a lot of functions such as spatial information search, hydrology and water quality information inquiry and statistics, water environment quality assessment, lake eutrophication assessment, embodying the visualization of systems analysis sufficiently. The system has been mainly studied and developed in the technology of lake eco-environment management, and also provided an intuitionistic, universal, convenient and reliable management tool for Nansihu water eco-environment management.

GIS and L-THIA Based Analysis on Variations of Non-point Pollution in Nansi Lake Basin,China

Non-point source(NPS) pollution is the main threat to regional water quality,and the estimation of NPS pollution load has become an important task for NPS pollution control in China.Combined with geographical information system(CIS),the longterm hydrologic impact assessment(L-THIA) model was used to evaluate the temporal-spatial changes of chemical oxygen demand(COD),total nitrogen(TN) and total phosphorus(TP) in Nansi Lake basin from 2000 to 2010.The results show:1) the estimated COD,TN and TP loads in 2010 are260017.5,111607.7 and 6372.0 t with the relative errors of 2.1%,2.0%and-8.8%respectively,and more than 90%concentrated in the raining period from June to September;2) cultivated land and construction land take up more than 80%of the whole Nansi Lake basin,and the proportions of the three kinds of NPS pollution loads coming from cultivated land and construction land are more than 98%;3) during 2000-2010,the COD,TN and TP loads increase by 8801.6,180.3 and 71.9 t respectively,and become the main impact factors on the water quality of Nansi Lake.

Analysis of Land Use Changes in the Watershed of Nansi Lake,Shandong Province

Change of land use is related to regional food security and ecological security.This study analyzed structural changes,quantity changes and spatial changes of land resource utilization in the watershed of the Nansi Lake,Shandong Province from 2000 to 2012 on the basis of land use investigation data and relevant socio-economic data in the study period.It is to disclose the problems in the utilization of local land resources,and provide scientific support for the scientific management of land resources and sustainable development of social economy.

Economic Development Mode and Countermeasure Research on the Nansi Lake Drainage Area Based on Circular Economy

Firstly,it is pointed out that circular economy should be vigorously developed in the Nansi Lake Drainage Area,and the connotation of circular economy is expounded.Then,problems in developing circular economy in Nansi Lake Drainage Area are analyzed from the aspects of agriculture,industrial enterprises,and waste utilization.Finally,combining with the four modes of peasant household,enterprise,region and society in the development of circular economy,corresponding countermeasures are put forward for the circular economy in Nansi Lake Drainage Area,such as establishing the government guidance mechanism for big agriculture circular economy in Nansi Lake Drainage Area,constructing incentive systems for industrial enterprises adopting circular economy in Nansi Lake Drainage Area,adjusting the industrial structure of Nansi Lake Drainage Area,and optimizing the energy consumption structure.

EFFECTS OF AQUATIC VEGETATION ON FLOW IN THE NANSI LAKE AND ITS FLOW VELOCITY MODELING

Aquatic vegetation has significant effects on flow in waters. In this article, four types of water areas were analyzed according to the field survey on water depth and vegetation in the Nansi Lake for the East Line Project of Water Transfer from South to North in China （WTSNC）. The depth-averaged 2-D hydrodynamic models with and without consideration of the effects of aquatic vegetation on flow were established to simulate flow fields in vegetated and non-vegetated zones in the Nansi Lake. With the established models, flow fields were predicted under the conditions of water transfer from south to north. The results indicate that when the drag force term exerted by aquatic vegetation is considered, the computed velocities agree well with the measured data, whereas as the drag term is taken into account, the computed velocities are obviously larger than the measured data in the vegetated zone and considerably smaller in the non-vegetated zone, and the error range between the two velocities is large if this problem is dealt with the method of increasing the roughness coefficient of the lake-bed to reflect the vegetation drag force. In addition, it is demonstrated that the emerged vegetation exerts larger effects on flow than submerged vegetation comparing the results in the Emerged Vegetation （reed） Zone （EVZ） and the Submerged Vegetation Zone （SVZ）.

Variation of cyanobacteria with different environmental conditions in Nansi Lake,China

Nansi Lake is located on the east line of the South-to-North Water Diversion Project in China. A comprehensive study was carried out to investigate the spatial and temporal distribution of cyanobacteria in the lake from June 2008 to May 2011 based on monthly sample monitoring from five stations. The effect of environmental factors on cyanobacterial abundance was also evaluated. The eyanobaeterial community contained 15 genera and 23 species. The cyanobacterial abundance of each monitoring station ranged from 0 to 1.53x 107 cells/L with an average of 1.45~ 106 cells/L, which accounted for 11.66% of the total phytoplankton abundance. The dominant species of cyanobacteria were Pseudanabaena （32.94%） and Merismopedia （19.85%）, not the bloom-forming algae such as Microcystis and Anabaena. In addition, the cyanobacterial community structure and water quality variables changed substantially over the survey period. Redundancy analysis （RDA） suggested that temperature and phosphorus were important environmental factors that affected cyanobacteria. Temperature was the most important factor affecting cyanobacterial abundance. The effect of phosphorus on cyanobacterial abundance was more notable in warm periods than in periods with low temperature.

Human Influence on Heavy Metal Distribution in the Upper Lake Nansi Sediments, Shandong Province, China

Core and surface sediment samples were collected from three sub-lakes (Lake Nanyang, Lake Dushan and Lake Zhaoyang) in the Lake Nansi Basin, Shandong Province. In order to reveal the characteristics of spatial and historical distribution of heavy metals in different sub-lakes of the Upper Lake Nansi, heavy metal (As, Cr, Cu, Hg, K, Mn, Ni, Pb, Zn, Al, Fe, Ti and V) concentrations of sediment samples were investigated. Based on the activity of 137Cs in the sediments, the modern accumulation rate of Lake Nansi sediments is 3.5 mm/a. Our results show that the whole Upper Lake Nansi has been already polluted by heavy metals, among which Lake Nanyang has been polluted seriously by mercury, as well as by lead and arsenic, while Lake Dushan has been most seriously polluted by lead and arsenic. Historical variation of heavy metal (Cr, Cu, K, Ni, Zn, Al, Fe, Ti and V) concentrations shows an abrupt shift in 1962, resulting in a division of two periods: from 1957 to 1962 when metal enrichment increased with time, and from 1962 to 2000 when it decreased with time, while that of some anthropogenic elements such as Hg, Pb and Mn tend to increase toward the surface. However, the variation trend of As in the sediments is different from that of Hg, Pb and Mn, with its maximum value appearing in 1982. Since 1982 the concentrations of As have decreased due to the forbidden use of arsenite pesticides. This variation trend revealed changes in manner of human activity (coal combustion, waste discharges from both industries and urban sewage) within the catchment during different periods.

基于集成学习的内陆水体叶绿素a浓度反演

利用卫星数据监测内陆或水质状态,对生态决策具有重要意义。基于具有高时空分辨率的哨兵二号卫星数据,联合2种集成学习算法反演山东省南四湖叶绿素a(Chla)浓度,结果表明经遥感反射率校正后的哨兵二号数据更加适用于水质反演。XGBoost模型在五折交叉验证反演结果上表现最优(R^(2)=0.732 5,RMSE=9.168 1μg/L),反演结果更符合实际情况。因此,使用该模型反演南四湖叶绿素a浓度,能较好地掌握其时空变化情况,对其他区域类似研究可提供一定参考。

山东南四湖菹草时空分布及其对水环境的影响

为了解南四湖菹草种群的变化特征及其对水环境的影响规律,利用遥感影像技术监测南四湖2017—2022年菹草时空分布格局,从透明度(SD)、溶解氧(DO)、化学需氧量(COD)、总氮(TN)、总磷(TP)、叶绿素a(Chla)6个指标分析菹草在不同生长史阶段对水环境的影响。结果表明:2017—2020年南四湖菹草面积一直处于增长趋势,从2017年的208.65km^(2)快速增长到2020年的311.81km^(2),增长率达49.44%;2021年菹草面积有所减少,2022年较2021年有所增加。菹草在整个生长周期内对水环境产生双重影响,菹草生长过程中吸收水体中的N、P等营养盐,增加水体DO,有利于改善水体理化性质;但菹草死亡腐败后,分解产生较多有机质,使得COD浓度升高,同时消耗水中DO、Chla含量逐渐增加,导致水体透明度下降,引起水质恶化。为保障水质安全,应加大菹草综合治理和资源化利用研究,合理控制菹草的生长规模。

冬季调水期南四湖水体温室气体溶存浓度及其影响因素

为了解冬季调水期南四湖表层水中温室气体的溶存浓度及其排放通量,采集南四湖各湖区和主要入湖河流的河口区表层水及气体样品,分析了水体的理化指标以及CO_(2)、CH_(4)和N_(2)O的溶存浓度,采用薄边界层扩散模型法估算了水—气界面排放通量,并探讨了影响调水期南四湖温室气体溶存浓度的主要因子.结果表明,调水期南四湖表层水中N_(2)O、CH_(4)和CO_(2)浓度分别为(23.0±6.13)nmol·L^(-1)、(0.15±0.10)μmol·L^(-1)和(52.4±11.4)μmol·L^(-1),均处于高度过饱和状态,排放通量分别为(0.22±0.18)μmol·m^(-2)·h^(-1)、(3.95±2.73)μmol·m^(-2)·h^(-1)和(658±336)μmol·m^(-2)·h^(-1);浓度和排放通量多与冬季其他湖泊相当,但低于平原河网.各温室气体浓度、饱和度和排放通量整体呈现自上级湖向下级湖降低的趋势,且在河口区和二级坝附近水域浓度较高,同时N_(2)O和CO_(2)浓度在微山湖湖心区出现带状高值区,而CH_(4)相对较低.各温室气体浓度与水质参数间具有一定的相关性,其中,N_(2)O浓度与NO_(3)^(-)、NO_(2)^(-)浓度呈显著正相关,CH_(4)与TN呈显著负相关,CO_(2)与pH、SD呈显著负相关,与DOC呈显著正相关,反映了水质对温室气体溶存浓度的影响.研究结果为评估调蓄湖泊在调水期对大气温室气体的影响提供了基础数据支撑.

基于水体交换能力的调水工程对底栖动物群落影响研究

水文条件的改变会引起水生态系统的波动变化,大型调水工程的实施会改变水生生物群落结构。本研究分别调研了南四湖和东平湖在调水工程实施前后一段时间的大型底栖动物群落结构,模拟分析了调水工程引起的湖泊水龄变化特征,从水体交换能力的角度探讨了大型调水工程对湖泊中大型底栖动物群落的影响。结果显示,调水工程运行一段时间后,东平湖中大型底栖动物群落在年尺度上从由小体型的水生昆虫类主导转变为由大体型的软体动物主导,南四湖中软体动物的优势在调水工程实施之后更加凸显。在季节尺度上,软体动物占比通常在调水期(非雨季)减小,而在非调水期(雨季)增大。调水工程的实施改变了湖泊水动力场特征,在年尺度上增强了湖泊水体交换能力,调水入流与入湖径流的叠加使湖泊水体的高流速时间变长,这不利于小体型物种稳定生长,进而导致在年尺度上大体型软体动物的占比逐渐增大。此外,调水工程的实施主要是提升了非雨季湖泊的水体交换能力,但增加调水后的非雨季湖泊水体交换能力仍然小于雨季,这也导致软体动物占比在调水工程实施前后均呈现在雨季减小在非雨季增加的规律。

极端干旱对南四湖湿地景观影响的遥感分析

在气候变化加剧背景下,研究湿地的干旱响应特征具有重要意义。以草型湖泊南四湖2002年发生的极端干旱事件为例,基于干旱年及正常年Landsat遥感数据、长时序气象数据、帕默尔干旱指数(PDSI)数据等,计算南四湖归一化植被指数(NDVI)、修正的归一化水体指数(MNDWI)、植被覆盖度(FVC),并分析了干旱前后的景观指数变化特征,包括斑块数量(NP)、斑块密度(PD)。结果表明:1)干旱年降水的显著偏少及气温的异常偏高是导致这次干旱事件的主因;2)干旱年南四湖水域面积大幅减少,并在10月出现干湖现象;3)湿地植被特征与干旱程度显著相关(P<0.05)。随着干旱的加重,植被面积及NDVI、FVC呈现先增后减的趋势,在8月达到最大后开始减小;4)相比正常年份,干旱年湿地景观特征差异显著。干旱年水体面积显著下降,水体斑块数量增加912个、斑块密度增加15.47,水体景观趋于破碎化,而植被面积显著增加,植被景观破碎化降低。研究可为湖泊湿地的气候适应性管理提供一定科学指导。

南四湖出湖口沉积物-水界面中营养盐分布特征分析及释放风险评估

为了解决南四湖出湖口沉积物-水界面中磷酸盐、氨氮和硝态氮等营养盐释放风险控制缺乏科学依据的问题,利用薄膜扩散梯度技术、高分辨率孔隙水采样技术分析南四湖出湖口沉积物-水界面中营养盐浓度的垂直剖面分布特征,并根据有效态磷、有效态氨氮和有效态硝态氮的浓度,计算三者的净扩散通量,评估三者的释放风险。结果表明:非泄洪期南四湖出湖口上覆水中的溶解态磷浓度低于孔隙水中的,表明沉积物孔隙水中的溶解态磷可能会因浓度梯度的存在而向上覆水中扩散;根据连续分级提取法,钙结合态磷是南四湖出湖口沉积物中磷元素的主要赋存形态,表层沉积物中的不稳定磷元素含量高于深层沉积物中的;有效态磷与有效态铁呈显著正相关,说明南四湖出湖口沉积物-水界面中有效态磷的释放受铁氧化物还原释放影响;有效态磷、有效态氨氮和有效态硝态氮的净扩散通量分别为17.58、1.16、-40.72 ng/(cm^(2)·d),说明有效态磷和有效态氨氮有从沉积物向上覆水中释放的潜在风险。

数字孪生南四湖防洪调度模型研究及应用

南四湖具有独特的水系特征,洪水预报调度难度大。为提升数字孪生流域智能化水平,设计开发了南四湖防洪调度模型集,实现了洪水预报、流场计算、工程调度等功能。介绍了南四湖防洪调度模型布局,以及概念性水文预报模型、水库调度模型、分布式时空变源模型、河道演进模型、湖区洪水演进模型、洪水调度模型等主要内容的研发情况和成果,从防洪演练、洪水预报、流场仿真、工程调度典型应用等方面,介绍了模型集对防洪调度工作的支撑。相关成果为沂沭泗流域防洪调度模型提供了基础和标准框架,为数字孪生流域模型研发提供借鉴和参考。

南四湖消落带底泥有机磷赋存形态及分布特征

研究南四湖消落带底泥有机磷赋存形态及分布特征,有利于全面揭示湖区各形态磷迁移转化规律,对南四湖富营养化防控及南水北调东线调水水质保障具有重要的科学意义。以南四湖消落带底泥为研究对象,采用改进Hedley连续分级提取法测定底泥中各形态有机磷含量,通过紫外可见分光光谱与三维荧光光谱技术表征底泥有机分子结构特征及稳定性,反映消落带有机磷结构及稳定性差异,运用Pearson相关性分析及主成分分析解析底泥各形态磷与其他理化指标的相关性。研究结果表明,南四湖消落带底泥总磷含量均值为679.90 mg/kg,其中有机磷(OP)占比20.03%~45.69%。各赋存形态有机磷含量及相对比例大小依次为:残渣态有机磷(67.58%)>钙结合态有机磷(16.61%)>铁/铝结合态有机磷(7.62%)>碳酸氢钠提取态有机磷(5.97%)>水提取态有机磷(2.22%)。南四湖消落带底泥OP含量及形态主要受内源影响,主要来自内源性微生物代谢。南四湖消落带西岸底泥磷释放风险高于东岸和南岸消落带。相关性分析发现,消落带底泥pH与磷含量显著负相关,表明随着底泥碱性的增强可能导致底泥磷向水体中释放的风险更高;底泥有机质与OP显著正相关,表明有机质可能是OP的重要载体;主成分分析发现底泥各形态磷呈正相关性,表明消落带底泥各形态磷具有同源性。研究结果可为南四湖湖区内源磷释放控制及富营养化风险防控提供科学依据。

南四湖富营养化状况分析与评价

本研究在对南四湖2021年1—12月南阳、独山、二级湖闸上、微山岛、韩庄闸5个监测站点浮游藻类和水环境质量监测的基础上,对其富营养化状况进行了分析与评价。结果表明,南四湖优势种群主要为绿藻门和硅藻门,全年藻细胞密度的波动范围在3.5~490×10^(4)个/L,未超过藻细胞浓度限值,全年没有发生水华事件。综合分析高锰酸盐指数、总磷、总氮、叶绿素a和透明度等指标,独山、二级湖闸上、韩庄闸闸上水质类别均为Ⅲ类,南阳站和微山岛站水质类别为Ⅳ类,主要污染物为总磷,超地表水Ⅲ类标准10.82和7.08倍。2021年南四湖营养化等级为轻度富营养。南四湖整体水域生态系统较稳定,水环境良好,本研究可为南四湖资源保护、南水北调东线工程建设及可持续发展提供依据。

基于氮氧同位素的南四湖硝酸盐来源解析

选取南水北调东线受水湖南四湖为研究对象,运用δ^(15)N-NO_(3)^(-)、δ^(18)O-NO_(3)^(-)同位素示踪技术和水化学分析方法,阐明了研究区水化学及不同形态氮分布特征,揭示了氮的转化过程,分析了硝酸盐来源,基于MixSIAR模型,对研究区水体中各硝酸盐来源贡献比例进行了定量识别.结果表明:南四湖无明显温跃层,水体呈碱性,水化学类型以SO_(4)^(2-)-Na^(+)型为主.下级湖中的氮以硝态氮为主,随着水体自净及沉积物吸附,浓度逐渐降低,入湖河流污染特征与湖水一致.研究区湖水硝酸盐形成过程以硝化作用为主,水体中的硝酸盐来源生活污水>土壤有机氮>合成化肥>大气沉降,基于MixSIAR源解析模型分析,贡献比例分别为51.3%、23.7%、16.4%、8.5%.

南四湖鸟类物种多样性调查

采用样线法,根据生境类型以及人为干扰情况等环湖设置样线(点),使用30×60倍单筒望远镜和10×20倍双筒望远镜以及长焦相机对不同生境的鸟类进行观察和记录,并采集照片等资料。2021年6月至2022年1月,在丰水期(2021年6—7月)与枯水期(2021年12月—2022年1月)对南四湖鸟类进行2次野外调查。通过此次调查共监测到鸟类14目34科76种,其中国家二级保护鸟类2种,《世界自然保护联盟濒危物种红色名录》中近危类物种1种、易危类物种3种。从居留型来看,南四湖鸟类中留鸟种类最多;从区系划分来看,古北界鸟类占绝对优势,但显示出一定的过渡性特征。南四湖鸟类物种多样性G-F指数为0.595 6,Sorenson相似性指数为0.509 8,说明丰水期与枯水期鸟类物种组成不相似。从此次调查结果来看,丰沛的食物、丰富的生境和修复的湿地生态系统吸引了越来越多的鸟类在南四湖区域栖息、觅食及居留。了解该区域鸟类种类组成和物种多样性对于加强南四湖区域的保护管理具有重要意义。