This study analyzed phytoplankton monitoring data (2019-2023) from the middle-lower reaches of the Xin River to clarify cyanobacterial spatiotemporal distributions and their environmental drivers. Sixty-six phytoplankton genera across seven phyla were detected, with Chlorophyta being the dominant phylum, followed sequentially by Bacillariophyta and cyanobacteria. The inter-annual variation of phytoplankton biomass ranged from 2.42 to 11.46 mg/L, while the cyanobacteria biomass varied from 0 to 2.63 mg/L, accounting for 7.54% of the total phytoplankton biomass. The dominant cyanobacteria species included Microcystis, Planktothrix, and members of Phormidioideae, with the dominant species showing some heterogeneity across different regions. For the study area, the average River Trophic Status Index (RSI) was recorded as 54.89, indicating seasonal water quality variations: favorable during the dry season; slightly polluted in most river sections during the rising period; moderately polluted in most sections during the wet period; and generally slightly polluted during the rece ssion period. Statistical analyses (Pearson correlation and redundancy analysis (RDA)) revealed that cyanobacteria and their dominant species had significant correlations (p < 0.05) with environmental factors including total phosphorus (TP), orthophosphate (PO4 3--P), dissolved total nitrogen (DTN), chemical oxygen demand (CODMn), Secchi Depth (SD), were the primary environmental factors driving the spatiotemporal distribution of cyanobacteria. This study provides for the first time an earlier seasonal emergence of cyanobacteria in lake entrance areas, addresses the domestic gap concerning inadequate attention to small and medium-sized rivers (e.g., the Xin River) relative to large lakes such as Taihu Lake and Chaohu Lake and holds crucial reference value for early warning systems aimed at preventing cyanobacterial encroachment into Poyang Lake.

Iron and calcium salts are two commonly used inactivators of sediment phosphorus (P). However, there is limited research on the effectiveness of their combined use. In this study, two enclosures (each 600 m2) were constructed in a eutrophic sub-lake within Poyang Lake (the largest freshwater lake in China), to examine the inhibitory effect of iron-calcium combined treatment (Fe&Ca treatment) on sediment P release. Subsequently, a sediment incubation experiment was conducted to investigate the impact of Fe treatment alone, Ca treatment alone, and Fe&Ca treatment on sediment P release fluxes and P fractions. The enclosure experiment demonstrated that the Fe&Ca treatment resulted in a decrease of 0.65 times in non-apatite inorganic P (NAIP) content in sediment, and an increase of 2.87 times in apatite P (AP) content. The sediment P release in the treated enclosure was significantly reduced by up to 90% under alkaline conditions compared to the control enclosure. In the sediment incubation experiment, Fe&Ca treatment effectively restrained P release and enhanced sediment AP content while reduced NAIP content. The transformation from NAIP to AP was likely primarily driven by Ca treatment, while Fe&Ca treatment stabilized water pH and consequently inhibited the release of sediment P and nitrogen. This study is the first to validate this transformation pathway and its inhibitory effect on P release. These findings emphasize the effectiveness of iron and calcium combination for minimizing the risk of P release from sediments, thereby offering a promising approach for in situ P control in lakes.

Microplastics (MPs) in freshwater environments, such as lakes, have become a significant issue in recent years. However, studies on the lakes of the Yunnan Plateau have been limited. To understand the pollution status and sources of MPs in Lake Chenghai (LCH), 36 sampling sites were selected for the surface water and sediment samples. Morphological identification, compositional analysis, abundance measurement, and spatial distribution mapping of the MPs were carried out. We also performed correlation analyses with hydrological parameters and physicochemical indexes of water and sediments. We aimed to uncover the spatial distribution patterns of the MPs in LCH, along with potential sources. Our findings revealed that all samples contained MPs and all of them were fibers. The abundance of MPs ranged from 90 to 770 n/m3 (329.44 rms) in the water and from 10 to 115 n/kg (43.19 rms) in the sediments, with particle sizes of 1-3 mm and less than 1 mm, respectively. Transparent MPs were prevalent, comprising 68% of the MPs found in the water and 63% in the sediments. The primary components of the MPs were polypropylene (PP), polyethylene terephthalate (PET), and man-made fibers (rayon). The spatial distribution showed an increasing concentration of MPs from south to north in the surface water, whereas the opposite trend was found in the sediments. Human activities, prevailing winds, and the river flowing into the lake influenced the spatial distribution pattern of the MPs. The abundance and assemblage characteristics of the MPs were directly correlated with the factors of nitrogen, phosphorus, and particle size in the water and sediments, but the correlation was not significant. The main source of MPs was the production and livelihoods of the neighboring residents, especially the use of fishing gears and nets. Since LCH shows significant pollution from MPs, there is an urgent need to control and manage the watershed in order to reduce the input of MPs in the future.

为弄清滇池外海蓝藻水华暴发时空变化规律及其影响因素,将滇池外海分为北、中、南3个区域,基于2002—2018年期间中分辨率成像光谱仪(MODIS)反演的水华面积,分析了上述3个区域蓝藻水华的时空变化特征.基于2007—2018年水文、气象和出入流数据,构建了外海三维水动力生态模型(AEM3D),并计算了各区域的水力滞留时间.通过冗余分析(RDA)、随机森林(RF)和斯皮尔曼相关分析方法,分析了影响以上区域蓝藻水华暴发的主要驱动因子.结果表明:2002—2018年期间,整个滇池外海区域年平均水华面积比(水华面积占该区域总面积比例)呈缓慢下降趋势,空间上由北向南依次递减,整个外海水华暴发面积最大主要发生在秋季.在外海北部区域,其东部水华较西部更为严重,而在中部和南部区域,呈现西部水华较东部更为严重的空间分布模式.通过对各影响因子的统计分析发现,风速、水温和日照时长是上述各区域中蓝藻水华暴发的主要决定性因素.水华暴发期间以西南风为主导风向,且上述区域的水华面积比随风速增加呈下降趋势.在外海各区域,水力滞留时间与水华暴发面积均呈显著正相关,空间上水力滞留时间由北向南逐渐增大,风速和风向是影响蓝藻水华空间分布规律和严重程度的主要因素.

Based on a review of material previously studied, and new water samples, species of the genus Amphorotia were investigated with respect to their morphology and geographical distribution, especially in subtropical Asian coastal areas.Six Amphorotia species from China are investigated.They all possess amphoroid frustule symmetry, presence of spines and, when detected, a single plastid.These features as well as other details of the frustules were documented with light and scanning electron microscopy.Five of the taxa, A. reimerii, A. mokonensis, A. baicalensis, A. zhujiangensis, and A. curvata are newly recorded as fossil specimens in the Jianghan Plain.Further comments on the taxonomy and morphological variation of several known species are given.One taxon, A. liangyanlingii sp.nov.was discovered from freshwater samples in the Pearl River.This new species is most similar to A. zhujiangensis Wu, Williams et Flower when observed in LM, but can be distinguished by ultrastructural details when viewed with the scanning electron microscope (SEM).Taxonomical studies of species in the genus Amphorotia are considered together with their biogeography and ecology.

To quantitatively evaluate the effects on water quality improvement caused by reducing external loadings entering Lake Erhai through inflow rivers, a one-dimensional hydrodynamic and ecological model (DYRESM–CAEDYM) was set up to simulate the water quality and water level variations. The calibrated and validated model was used to conduct six scenarios for evaluating the water quality responses to different amounts of external loading reduction at Lake Erhai. The results show (1) the total nitrogen (TN) concentration of Lake Erhai will be higher than 0.5 mg/L without any watershed pollution control during April–November 2025, which cannot meet Grade II standard of the China Surface Water Environmental Quality Standards (GB3838-2002). (2) External loading reductions can significantly reduce the concentrations of nutrients and Chla at Lake Erhai. The effects of water quality improvement will be proportional to the reduction rate of external loading reductions. (3) Internal release might be an important source of pollution It needs to be seriously considered as well as external loading for mitigating the eutrophication at Lake Erhai in the future.

Blue–green infrastructure provides a variety of ecosystem services and is becoming an increasingly vital part of urban ecosystem protection. It is an ecological facility for ecological conservation and environmental protection, and a foundation for realizing people’s needs for a better life. This study selects indicators from four dimensions: social, economic, environmental, and ecological, and the demand for blue–green infrastructure is assessed comprehensively. The results show that: (1) the demand for blue–green infrastructure varies spatially with the development of the city; (2) the total demand for blue–green infrastructure in Nanjing from 2000 to 2020 shows a pattern of “high in the center and low in the periphery”; (3) the level of economic development, urban spatial pattern, and decision management orientation have different degrees of influence on the demand for blue–green infrastructure, with the urban spatial pattern having the greatest impact. Therefore, in the future, blue–green infrastructure should be optimized by taking into account the spatial characteristics of demand in Nanjing.

湖泊是重要的淡水资源.在气候变化和人类活动的背景下,湖泊提供的淡水资源越来越有限,湖泊水量的计算对于了解全球和区域范围内的可利用淡水资源量具有重要意义.在洱海流域,日和月尺度上的出入流数据几乎没有,仅能从文献中查找到部分年尺度的入流数据,为洱海水量的精确计算带来了困难,因此,不得不借助水文或水动力模型来进行水量的精确反演.论文基于洱海实测水位、水位—库容曲线和水量平衡的方法,建立DYRESM计算洱海2000-2020年主要出入湖河道逐日流量,运用新安江模型反演洱海同时期逐日入湖流量,探究新安江模型在高原地区的适用性,根据2000-2020年实测出入湖流量年总值对2个模型模拟结果进行评价和对比分析.结果表明:①DYRESM模拟2000-2020年洱海多年平均入湖和出湖流量分别为6.88×108、6.08×108m3,逐年入湖和出湖模拟流量与实测值间相关系数r分别达到0.97和0.99.②基于DYRESM得出的洱海逐日入湖流量,构建新安江模型,将新安江模型模拟得到的2000-2020年洱海逐日入湖流量与DYRESM模拟结果进行了对比,拟合效果理想,洱海流域率定期和验证期间纳什效率系数(NSE)分别为0.68和0.55,r达到0.94.新安江模型参数在不同地区的参数对比结果中,差异性较大的主要为地表径流消退系数(Cs)和自由水容量(Sm),洱海流域内Sm值相较于平原地区数值偏大,Cs值具有明显地域性.③对比2000-2020年洱海入湖流量的模拟值与实测值,得到DYRESM模拟值与实测值间r=0.97,新安江模型模拟值与实测值间r=0.92,可见DYRESM在出入流重建模拟中的表现优于新安江模型.

To assess water quality (WQ) online for assuring the safety of drinking water, a novel early warning system integrating a high-frequency monitoring system (HFMS) and data quality control (QC) was developed at Lake Qiandao. The HFMS was designed for monitoring water quality, nutrient inputs by main tributaries, water currents and meteorology at different sites at Lake Qiandao. The EWS focused on data availability, a QC method, a statistical analysis method and data applications instead of technological aspects for sondes, wireless data transfer and interface software development. QC was implemented before use to delete the abnormal values of outliers, to detect change points, to analyse the change trend, to interpolate discrete missing measurements, and find continuous missing or wrong observations caused by technical problems with the sonde. For demonstrating advantages and data availability, surface and profiling measurements at two sites were plotted. The plots show obvious seasonal and diel variations, demonstrating the success of integration of the system with advanced automated technology and good QC. This successfully developed system is now not only giving early warning signals, but also providing critical WQ information for the security of drinking water diverted to Hangzhou city through a tunnel of 110 km length. The automatic monitoring data with QC is also being used to produce initial conditions for WQ prediction based on a three dimensional hydrodynamic-ecosystem model.

The effects of global warming and precipitation changes on water temperature and thermocline parameters, such as thermocline depth, thickness, and strength, were assessed. A catchment model, coupled with a reservoir thermal model with meteorological input calculated by a downscaled general circulation model (GCM) projection under three representative concentration pathways (RCPs), was applied to the Xin’anjiang Reservoir, located in southeast China. The results indicate that water temperature in each layer increased (decreased) with the rise (decline) in air temperature, especially the surface water temperature. There was a significant negative (positive) correlation between thermocline depth (strength) and air temperature during the period of stratification weakness. The most sensitive phenomenon of water temperature-to-precipitation changes occurred in the middle layer (depth = 30 m). Additionally, the thermocline depth and thickness increased with decreases in hydraulic residence time, which were caused by precipitation increases. According to the simulation experiments driven by RCP outputs, mean water temperature in each water layer in the future (2096–2100) has a strong response to increases in air temperature, which is projected to increase by 0.11–0.62 °C for RCP2.6, 0.76–1.19 °C for RCP4.5, and 1.50–2.35 °C for RCP8.5, compared to the baseline (2012–2016). However, mean water temperature in each water layer from 2096 to 2100 underwent a slight decrease caused by precipitation changes, with a 0.03–0.25 °C decrease for RCP2.6, 0.07–0.40 °C for RCP4.5, and 0.04–0.29 °C for RCP8.5, compared to 2012–2016. The mean thermocline depth in the future (2096–2100) will be significantly decreased, while the mean thermocline thickness will be slightly increased. Over a multiyear timescale, the impacts of air temperature changes are stronger than those induced by precipitation variations. However, the effects of hydraulic residence time changes caused by precipitation changes (especially rainstorm) should be considered in the management of deep reservoirs.

为分析千岛湖极端水位变化对温跃层的影响,在水温垂直剖面数据缺测情况下,采用率定后的一维水动力模型DYRESM模拟了不同水位变幅下的温跃层,并设置了极端水位变化情况(情景1)和正常水文条件(情景2)两种情景进行对比分析;基于湖泊分析程序Lake Analyzer计算了两种情景下温跃层表层和底层深度、温跃层厚度和施密特稳定度等.模拟结果表明:情景1水体混合期为2013年11月20日至2014年3月23日,同时段内情景2水体混合期则为2013年12月5日至2014年3月16日;情景1在高水位时,湖体从上到下呈"混合层、温跃层、均温层(30～40 m水层)、温跃层、均温层"的双温跃层结构,同时段内情景2则呈"混合层、温跃层、均温层"的单温跃层结构;情景1与情景2相比,平均水位低2.24 m,施密特稳定度均值低119.19 J/m2,可见极端水位变化条件下出现的低水位情况能显著降低水体稳定度.

Lake Xingyun is a hypertrophic shallow lake on the Yunnan Plateau of China. Its water quality (WQ) has degraded severely during the past three decades with catchment development. To better understand the external nutrient loading impacts on WQ, we measured nutrient concentrations in the main tributaries during January 2010–April 2018 and modelled the monthly volume of all the tributaries for the same period. The results show annual inputs of total nitrogen (TN) had higher variability than total phosphorus (TP). The multi-year average load was 183.8 t/year for TN and 23.3 t/year for TP during 2010–2017. The average TN and TP loads for 2010–2017 were 36.6% higher and 63.8% lower, respectively, compared with observations in 1999. The seasonal patterns of TN and TP external loading showed some similarity, with the highest loading during the wet season and the lowest during the dry season. Loads in spring, summer, autumn, winter, and the wet season (May–October) accounted for 14.2%, 48.8%, 30.3%, 6.7%, and 84.9% of the annual TN load and 14.1%, 49.8%, 28.1%, 8%, and 84.0% of the annual TP load during 2010–2017. In-lake TN and TP concentrations followed a pattern similar to the external loading. The poor correlation between in-lake nutrient concentrations and tributary nutrient inputs at monthly and annual time scales suggests both external loading and internal loading were contributing to the lake eutrophication. Although effective lake restoration will require reducing nutrient losses from catchment agriculture, there may be a need to address a reduction of internal loads through sediment dredging or capping, geochemical engineering, or other effective measures. In addition, the method of producing monthly tributary inflows based on rainfall data in this paper might be useful for estimating runoff at other lakes.

This research addresses the separate and combined impacts of changes in climate and land use/land cover on the hydrological processes and sediment yield in the Xin’anjiang Reservoir Basin (XRB) in the southeast of China by using the soil and water assessment tool (SWAT) hydrological model in combination with the downscaled general circulation model (GCM) projection outputs. The SWAT model was run under a variety of prescribed scenarios including three climate changes, two land use changes, and three combined changes for the future period (2068–2100). The uncertainty and attribution of the sediment yield variations to the climate and land use/land cover changes at the monthly and annual scale were analyzed. The responses of the sediment yield to changes in climate and land use/land cover were considered. The results showed that all scenarios of climate changes, land use/land cover alterations, and combined changes projected an increase in sediment yield in the basin. Under three representative concentration pathways (RCP), climate change significantly increased the annual sediment yield (by 41.03–54.88%), and deforestation may also increase the annual sediment yield (by 1.1–1.2%) in the future. The comprehensive influence of changes in climate and land use/land cover on sediment yield was 97.33–98.05% (attributed to climate change) and 1.95–2.67% (attributed to land use/land cover change) at the annual scale, respectively. This means that during the 2068–2100 period, climate change will exert a much larger influence on the sediment yield than land use/land cover alteration in XRB if the future land use/land cover remains unchanged after 2015. Moreover, climate change impacts alone on the spatial distribution of sediment yield alterations are projected consistently with those of changes in the precipitation and water yield. At the intra-annual scale, the mean monthly transported sediment exhibits a significant increase in March–May, but a slight decrease in June–August in the future. Therefore, the adaptation to climate change and land use/land cover change should be considered when planning and managing water environmental resources of the reservoirs and catchments.

在极端气候事件频发和人类活动加剧的背景下,抚仙湖水位波动显著,尤其是2009-2012年极端干旱事件的发生,使抚仙湖平均水位(1721.31 m)低于法定最低水位(1721.65 m),给生态环境安全带来严重威胁.因此,找到合适有效的湖泊水位模拟方法,对气候变化影响下的未来水位进行预测,并做好相应的应对准备,对湖泊生态系统的保护至关重要.本文运用DYRESM水动力模型对抚仙湖1959-2050年水位进行了模拟.因抚仙湖流域尚无长时间序列的历史水文观测数据,故利用模型和水量补偿法对抚仙湖入湖水量进行反推,构建了降水量-入湖水量的回归方程,并通过有效的实测入湖水量和水位数据,对回归方程的精度进行了检验.利用全球气候模式BCC-CSM2-MR中SSP245和SSP585两种情景提供的未来气候预估数据,运用DYRESM预测了抚仙湖2021-2050年水位变化趋势.结果表明:(1)构建的DYRESM水动力模型和降水-入湖水量回归方程精度较高,模型结果能很好地反映抚仙湖水位的年际和年内变化趋势,且能有效捕捉到抚仙湖的水位峰值.(2)在SSP245和SSP585两种情景下,抚仙湖2021-2050年多年平均水位分别为1722.98和1723.93 m,较1959-2017年平均水位1721.77 m分别升高1.21和2.16 m.两种情景下抚仙湖未来水位均有部分时段超过法定最高蓄水位(1723.35 m),但均高于法定最低水位.因此,未来气候变化对抚仙湖水量的影响有限,并不会导致水位过低,当水位超过法定最高蓄水位时,可通过控制出流闸门将水位调节在合理范围内.

为定量揭示暴雨径流对大型水库外源总磷(TP)负荷量的影响,构建新安江模型,结合TP浓度高频在线监测数据,计算千岛湖主要入库河流新安江街口断面逐日TP负荷量,并在此基础上划分暴雨径流携带TP负荷量对新安江TP年总入库负荷量的贡献.结果表明:①近60年来,千岛湖流域年暴雨雨量占年降雨总量的28.1％,平均暴雨频次为6.2次/a,年暴雨雨量和频次均在0.001显著性水平上呈上升趋势;②基于逐日流量模拟和高频水质监测数据计算的入库TP负荷量为基于逐月常规监测数据计算结果的2.9倍;③典型年(2020年5月1日—2021年4月30日)通过街口断面进入千岛湖的径流量和TP负荷量分别为96×108 m3和1506 t,其中由暴雨产生的径流量和TP负荷量占比分别为47.9％和69.4％.研究显示,暴雨事件对水库外源磷负荷的贡献较大,暴雨径流携带高浓度磷的汇入对水库水质和生态系统健康构成较大威胁,采用高频监测网络与水文数值模型高效融合的方法,能有效提升水库TP外源负荷量的计算精度,可为加强认识水库磷污染过程、保障水库水质安全提供科技支撑.

There are many rivers flowing from complex paths into Lake Dianchi. At present, there is a lack of inflow and water quality monitoring data for some rivers, resulting in limited accuracy of statistical results regarding water volume and external loading estimations. In this study, we used DYRESM to estimate the water volume entering Waihai of Lake Dianchi from 2007 to 2019 without historical hydrological observation data. Then, we combined this information with the monthly monitoring data of water quality to calculate the annual external loading. Our results showed that: (1) DYRESM could effectively capture the extreme changes of water level at Waihai, showing its reliable applicability to Lake Dianchi. (2) The average annual inflow of rivers entering Waihai was about 6.69 × 108 m3. The fitting relationship between river inflow and precipitation was significant on annual scale (r = 0.74), with a higher inner-annual fitting coefficient between them (r = 0.98), thus suggesting that precipitation and its caused river inflows are the main water source for Waihai. (3) From 2007 to 2010, the river loadings remained at a high level. They decreased to 2445.44 t (total nitrogen, TN) and 106.53 t (total phosphorus, TP) due to a followed drought in 2011. (4) The river loading had annual variation characteristics. The contribution rates of TN and TP loading in the rainy season were 63% and 67% respectively. (5) Panlong River, Daqing River, Jinjia River, Xinbaoxiang River, Cailian River and Hai River were the main inflow rivers. Their loadings accounted for 81.3% (TN) and 80.3% (TP) of the total inputs. (6) River loadings have gradually reduced and the water quality of Waihai has continually improved. However, Pearson analysis results showed that the water quality parameters were not significantly correlated with their corresponding external loading at Waihai, indicating that there might be other factors influencing the water quality. (7) The contribution rates of internal release to the total loads of TN and TP at Waihai were estimated to be 7.6% and 8.9% respectively, suggesting that the reductions of both external and internal loading should be considered in order to significantly improve the water quality at Waihai of Lake Dianchi.

Anthropogenic eutrophication can significantly alter the nutrient balance in aquatic environments. Changes in nutrient dynamics (nutrient loads and stoichiometry) have profound, usually negative, impacts on aquatic ecosystems, triggering catastrophic regime shift and threatening water resource security and ecosystem sustainability. However, the researches to date have tended to focus on laboratory control experiments or short-term field observations, with few of them using paleolimnological techniques to address long-term effects of changing nutrient dynamics in aquatic ecosystems. Hence, a multi-proxy (diatom and geochemistry) paleolimnological reconstruction, integrated with a 10-year-long monitoring dataset (2001–2012), is developed here to rebuild a 53-year eutrophication history (1959–2012) of the large, subtropical Dashahe Reservoir in South China. Multiple statistical methods consistently revealed a significant ecological change in the reservoir ecosystem during the mid-1980s. Before the shift (1959–1985), both planktonic (e.g. Aulacoseira ambigua and A. granulata) and benthic (e.g. Encyonema minutum and Gomphonema biceps) diatoms co-dominated the assemblages with higher diversity, lower biomass and planktonic/benthic diatom ratios (P/B ratios) characterizing a clean water system. After the shift (1986–2012), the planktonic diatoms Aulacoseira and Discostella became overwhelmingly dominant, with lower diversity, higher diatom biomass and P/B ratios typical of eutrophic “polluted” water systems. Despite the apparent dual control by nutrient loadings (N and P) and stoichiometry (N/P), the non-linear relationship between N/P stoichiometry and diatom response roughly fits a typical threshold-like regime shift scenario, suggesting that the diatom assemblage shift occurred mainly in response to a certain threshold N/P ratio (~3.9). These results strongly suggest that nutrient stoichiometry and N overloading should receive more attention in the sustainability management of subtropical reservoir and lake systems.

A main cause of water eutrophication in lakes or reservoirs are nutrient enrichment, of which variations can be influenced by climatic changes and anthropogenic activities. It was reported that rainfall may lead to a short-term increase in nutrients that threaten the water quality of lakes or reservoirs. Daily meteorological data collected over the last few years in the Lake Qiandaohu basin highlight an increase in the frequency of extreme rainfall events. The relationships between nutrient (nitrogen and phosphorus) concentrations in the lake and external loading discharged into the lake during 2013-2016 were analyzed. Meanwhile, the fluid movement and the diffusion of the pollutants from the catchment were simulated by the ELCOM model. These were in order to evaluate the possible role of extreme precipitation events in affecting the nutrient availability in the lake. Our results show that, for the largest inflow (the Xinanjiang River), 32.5% of annual TN and 32.8% of annual TP were caused by rainstorm, respectively. The time of pollutant migration could be greatly shortened by heavy rains. For lakes and reservoirs, extreme precipitation will not only lead to a sharp increase in inflow but also result in a significant increase in nutrient loading in a short period of time. Therefore, rainstorms can be an important factor of climate-induced eutrophication in lakes or reservoirs.

Intermittent turbulent bursts have great impacts on sediment resuspension in coastal regions, tidal estuaries, and lakes. In this study, the role of turbulence structure on sediment resuspension was examined at Meiliang Bay of Lake Taihu, the third largest freshwater lake in China. The instantaneous three-dimensional velocity and suspended sediment concentrations were synchronously recorded by Acoustic Doppler Velocimetry (ADV) and Optical Backscatter Sensor (OBS) placed close to the lakebed. Statistical and quadrant analyses results revealed that the coherent structure contributed significantly to sediment particle entrainment. The intermittent burst events (dominant ejection and sweep) were the main energy source for sediment resuspension processes. 99.2% of turbulent sediment fluxes were triggered by ejection and sweep events, whereas the contributions coming from the outward interactions and inward interactions were relatively small. The large-amplitude burst events in the coherent structure dominated the influence on the sediment diffusion. Additionally, it was found that instantaneous sediment particle entrainment occurred earlier than the mean critical shear stress, which was induced by the stochastic nature of turbulence. The amount of sediment flux considering the turbulence characteristics was one or two larger magnitudes than the flux amount assessed by the time-averaged flow field, which indicated the critical shear stress approach might underestimate the sediment resuspension. Therefore, the influence of turbulence performance on sediment entrainment shall be seriously considered when evaluating sediment flux and internal nutrient loads in Lake Taihu.