Groundwater drought poses a critical threat to regional water security and ecological integrity. However, its spatiotemporal evolution and response mechanisms to meteorological drought remain poorly elucidated. This study examines the spatiotemporal dynamics of groundwater drought and its propagation mechanisms in response to meteorological drought across the Yangtze River Basin (YRB) by integrating datasets from the Gravity Recovery and Climate Experiment (GRACE), the Global Land Data Assimilation System (GLDAS), and the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA5). We construct a Groundwater Drought Severity Index (DSI) based on groundwater storage anomalies (GWSA) and employ the Mann-Kendall (MK) test, Sen's slope estimator, and seasonal cross-correlation analysis to quantify drought characteristics. The results reveal a distinct "wet-dry-wet" regime shift across the basin, with groundwater drought events concentrated between 2006 and 2015. These events were predominantly mild to moderate in severity. Groundwater drought characteristics exhibit strong spatial heterogeneity: the downstream experiences frequent, prolonged, and severe droughts, whereas the midstream features high-frequency but short-duration and mild droughts. Groundwater drought exhibits pronounced seasonal heterogeneity in response to meteorological drought: rapid response (3-4 months) and strong correlation in summer, moderate lag (6-9 months) in autumn, and long lag (11-15 months) with weakened correlation in winter and spring. Summer and autumn responses are primarily driven by temperature and precipitation, whereas winter and spring dynamics shift toward human-driven dominance due to low temperatures and intensive water withdrawals. These findings reveal the complex spatiotemporal heterogeneity of drought propagation in the YRB, providing a foundation for season-specific water resource management.

The biofilm process for phosphorus (P) enrichment has low carbon requirements, high P recovery, and the potential for high P enrichment. Since the superiority of nitrite and nitrate for denitrifying phosphorus removal (DPR) and P enrichment has not been identified, a biofilm system was established to elucidate the effect of electron acceptors on DPR and P enrichment from the perspective of microbial properties, nutrient metabolism genes, and quorum sensing. The results indicated that nitrite increased intracellular P storage by 6.8 mg/g SS by promoting the proliferation of P, N, and C metabolism genes compared with nitrate, and increased Delta P/Delta N and P release to acetate absorption ratio (Prel/HAcupt) by 12.5 % and 19.0 %, respectively. Nitrite also affected the composition of EPS by upregulating the biosynthesis of amino acids and amino sugars, and nucleotide sugar metabolism, resulting in an increase in extracellular P storage by 15.2 mg/g SS. Moreover, nitrite accelerated microbial quorum sensing by stimulating the increase of quorum sensing functional genes, biofilm synthesis protein genes, and AHLs synthase genes, accelerating intracellular/extracellular P metabolism processes. The rise of TP storage led to changes in microbial metabolic patterns, accelerating the release of P during the anaerobic stage and increasing the P enrichment efficiency from 62.9 % to 74.5 %, resulting in the highest concentration of P enrichment solution (153.6 +/- 3.27 mg/L) was obtained under nitrite condition. This study provided a scientific basis for clarifying the mechanism of nitrite's effect in DPR systems and promoted the sustainable utilization of P resources.

In recent years, the Yellow River Basin has experienced frequent extreme climate events, with an increasing intensity and frequency of droughts, exacerbating regional water scarcity and severely constraining agricultural irrigation efficiency and sustainable water resource utilization. The accurate estimation of reference crop evapotranspiration (ET0) is crucial for developing scientifically sound irrigation strategies and enhancing water resource management capabilities. This study utilized daily scale meteorological data from 31 stations across the Yellow River Basin spanning the period 1960–2023 to develop various machine learning models. The study constructed four machine learning models—random forest (RF), a Support Vector Machine (SVM), Gradient Boosting (GB), and Ridge Regression (Ridge)—using the meteorological variables required by the Priestley–Taylor (PT) and Hargreaves (HG) equations as inputs. These models represent a range of algorithmic structures, from nonlinear ensemble methods (RF, GB) to kernel-based regression (SVR) and linear regularized regression (Ridge). The objective was to comprehensively evaluate their performance and robustness in estimating ET0 under different climatic zones and drought conditions and to compare them with traditional empirical formulas. The main findings are as follows: machine learning models, particularly nonlinear approaches, significantly outperformed the PT and HG methods across all climatic regions. Among them, the RF model demonstrated the highest simulation accuracy, achieving an R2 of 0.77, and reduced the mean daily ET0 estimation error by 0.057 mm/day and 0.076 mm/day compared to the PT and HG models, respectively. Under drought-year scenarios, although all models showed slight performance degradation, nonlinear machine learning models still surpassed traditional formulas, with the R2 of the RF model decreasing marginally from 0.77 to 0.73, indicating strong robustness. In contrast, linear models such as Ridge Regression exhibited greater sensitivity to changes in feature distributions during drought years, with estimation accuracy dropping significantly below that of the PT and HG methods. The results indicate that in data-sparse regions, machine learning approaches with simplified inputs can serve as effective alternatives to empirical formulas, offering superior adaptability and estimation accuracy. This study provides theoretical foundations and methodological support for regional water resource management, agricultural drought mitigation, and climate-resilient irrigation planning in the Yellow River Basin.

As a key nutrient for primary productivity in freshwater ecosystems, the effect of upper cascade reservoirs on the downstream phosphorus (P) loading is subject to an ongoing scientific debate in the Mekong River. To investigate the effects of cascade reservoirs on the forms of P and its bioavailability in surface sediment, two rounds of field research were carried out both in a free-flowing river (Nu River) and in the Upper Mekong River (Lancang River) during winter and summer. Results showed that while the P was trapped with sediments and environmental parameters changed significantly, high relative abundance of bioavailable phosphorus (BioP, generally include Fe-bound P, Al-bound P, and Organic P) in sediment was detected in reservoirs and at near the border between China and Myanmar. The increased Bio-P in reservoirs may be caused by sediments sorting, anaerobic surface sediments, appropriate temperature, longer residence time and algae-nutrient positive feedback loops. Accumulated Bio-P in sediments may elevate the phosphorus release to overlying water and exacerbate eutrophication in reservoirs. Considered the intense anthropogenic phosphorus loading, nutrients enrichment risk in the lower Mekong River should receive more attention in further research.

气泡释放是天然水体释放CH4的主要途径之一,准确量化水体气泡释放量对于辨析其"汇、源"特性至关重要.自然水体释放气泡的不连续性、不确定性使得监测其过程较为困难.本研究针对水体气泡释放监测难题,通过改进倒置漏斗型气泡通量监测装置提出了一种气泡释放过程连续监测方法.本方法测量对象为定长时间监测水域释放气泡的体积,经室内外实验验证,其理论量程为3.6～132 mL/(m2·min),测量结果能够较好的表征10～40 m水深缓流水体气泡体积通量变化特征.运用该方法于2021年6-11月对三峡水库支流香溪河库湾开展CH4气泡通量连续监测,并分析不同环境因子对其产生的影响.结果表明:监测期间,研究水域CH4气泡通量变化范围为0.02～8.13 mg/(m2·d),且各采样点间CH4气泡通量呈现较高的时空变异性;CH4气泡通量与水温、水体pH呈显著正相关关系,与水深及水体电导率呈显著负相关关系.其中,水深可能是决定水体是否通过气泡形式释放CH4的重要影响因素,水深超过38.35 m后水体可能不再通过气泡形式释放CH4.然而,这一水深阈值是否同样适用于三峡水库其它支流还需要更多实验验证.本研究对于揭示三峡水库典型支流气泡态CH4排放过程具有重要意义.

为分析小微黑臭水体修复过程中温室气体释放规律,选择典型小微黑臭水体分别设置污染拦截并生态修复(W1)、污染拦截(W2)和污染直排(W3)3 组围隔进行对比实验研究.结果表明,在实验期内,污染拦截并生态修复围隔中CO2、CH4 和N2O扩散通量分别为(5671.9±1189.5)、(39.2±10.1)和(4.2±2.2)μmol/(m2·h),其CO2 当量贡献率分别为 76.51%、6.54%和 16.95%;仅污染拦截围隔中CO2、CH4 和N2O扩散通量分别为(1139.3±1169.6)、(102.1±35.6)和(20.0±14.1)μmol/(m2·h),其 CO2 当量贡献率分别为 13.64%、15.12%和 71.24%;污染直排围隔中 CO2、CH4 和 N2O 扩散通量分别为(9140.3±256.4)、(1126.8±215.1)和(1.8±1.7)μmol/(m2·h),其 CO2 当量贡献率分别为 38.74%、59.04%和 2.22%.实验围隔中三大温室气体释放 CO2 总当量大小表现为:污染直排>污染拦截>生态修复.污染直排围隔(W3)中缺氧且沉积物有机质含量较高,有机质降解过程中消耗大量O2 并释放CH4 和CO2,导致其释放通量及当量贡献率较高;污染拦截围隔(W2)发生了水体富营养化及藻类水华,藻类光合作用产氧消耗 CO2 并释放 N2O,导致 N2O较高、CO2 较低,N2O是其当量最主要贡献者;污染拦截并生态修复围隔(W1)中DO较高,抑制CH4 产生并加速氧化,同时抑制反硝化作用导致N2O较低,减少了向大气的总温室气体排放.

为探究梯级水库运行对河流沉积物氮形态时空分布的影响,分别在枯水期和汛期对澜沧江和怒江沿程表层沉积物进行跟踪监测,并利用分级连续浸取分离法得到了离子可交换态氮(IEF-N),弱酸可浸取态氮(WAEF-N),强碱可浸取态氮(SAEF-N)和强氧化剂可浸取态氮(SOEF-N)等四种沉积物氮形态.结果表明:(1)怒江和澜沧江自然河流段可转化态氮(TTN)含量略低于水库段,沿程分布含量范围512.2～1548.5mg/L,同时期4种可转化态氮形态分布规律基本一致,枯水期 SOEF-N＞WAEF-N＞SAEF-N＞IEF-N,含量范围分别为 486.6～1424.8,3.3～83.1,1.4～88.8 和 1.2～10.7mg/kg;汛期WAEF-N＞SOEF-N＞SAEF-N＞IEF-N,含量范围分别为360.7～755.7,42.8～656.2,6.8～394.3和35.8～153.6mg/kg;(2)梯级水库运行导致有机质富集,颗粒物粒径变小,对WAEF-N的释放有抑制作用;梯级水库运行导致水库段沉积物粒径变小,而SOEF-N主要分布在细颗粒中,致使沉积物的矿化作用受到抑制,有机氮含量得到累积;水库段由于有机质含量的累积,IEF-N含量逐步升高;自然河道段表层沉积物基本以氧化环境为主,沉积物中SAEF-N更易释放,而在水库段基本处在弱还原或者还原环境下,导致SAEF-N累积在沉积物.

Nitrogen pollution caused serious environmental problems in reservoir ecosystems. Reducing nitrogen pollution by enhancing nitrogen removal in river sediments deserved intensive research. Distributions of nitrogen contents in sediment-water interface were characterized along the Xiangxi bay (XXB), a eutrophic tributary in Three Gorges Reservoir, China. More than 47% of total Kjeldahl nitrogen (TKN) and 67% of total organic nitrogen (TON) were degraded during burial. Higher TN, TON and NH4+ consuming at downstream sites indicated stronger nitrogen mineralization and release due to higher turbulence of the overlying density currents. Nitrifying bacteria, denitrifying bacteria, anaerobic ammonium oxidizing (anammox) bacteria and nitrite/nitrate-dependent anaerobic methane oxidation (N-DAMO) bacteria were detected in nitrate-ammonium transition zone. Nitrogen contents transitions were responded to microbial stakeholders indicated microbially mediated nitrogen cycling in sediments. The dissolved oxygen and nitrate availabilities were the key limits of denitrification and associated reactions. These results suggested microbial mediated nitrogen cycling processes in sediments were critical for nitrogen removal in aquatic ecosystems, and replenishing dissolved oxygen and nitrate was expected to enhance sediment denitrification and strengthen potential environmental self-purification.

It is essential to understand the mechanism of algal bloom and develop effect measures to control the hazard in aquatic environment, such as large reservoirs. In this study, a series of experiments, along with field observation from 2007 to 2016, were carried out to identify the hydrodynamic parameters that drive the algal bloom in the Three Gorges Reservoir (TGR), China, and their threshold values were determined. The results show that algae concentration was markedly diluted with a short retention time, and the threshold value of the retention time to avoid algal bloom was approximately less than 3 days. With strong stratification, the algae concentration was able to approach to the level of algal bloom in 10 days, even when the water temperature is lower than 12 °C. The ratio of mixing depth to euphotic depth (Zm/Ze) had significant negative correlations with both algae concentration and algae specific growth rate (SGR). The field monitoring data indicated that Zm/Ze is an important hydrodynamic parameter which sensitively affects algae growth and concentration. This study made the first attempt to determine Zm/Ze >2.8 to restrain algal bloom in the TGR. Our findings shed light on the influence of critical depth on the algal bloom in the TGR, and the results can serve to control algal bloom in reservoirs through discharge operation.

A unique riparian ecosystem has been created as a result of anti-seasonal flooding after reservoir operations, which notably influences the distribution patterns of plant communities and their functional characteristics in the riparian zone. Plant functional traits which reflect the physiological and ecological processes of plants in particular ecosystems are crucial for indicating the variations in the ecosystem structure and function. To better understand the adaptation strategies of plants to hydrological changes and provide a scientific basis for the selection of species in the re-vegetation of the newly formed ecosystems, 14 leaf functional traits and leaf economics spectrum (LES) of 19 dominant plants under different hydrological conditions were investigated in the water level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR). The results showed that anti-seasonal flooding has significant effects on the leaf functional traits of plants (P < 0.05). The net photosynthetic rate of annual plants was significantly higher than that of perennial plants (P < 0.05), and there was a significant correlation between leaf phenotypic and photosynthetic traits (P < 0.05). Canonical correspondence analysis showed that soil water content and available phosphorus were the main factors affecting the leaf function of dominant species, indicating that hydrologic factors were still important environmental factors affecting leaf functional traits of dominant species in the WLFZ. And annuals from the WLFZ have characteristics of thick leaves, high photosynthetic rate, short lifespan, and high nutrient concentrations, which make them close to the fast investment-return end of LES. On the contrary, perennials are close to the slow investment-return end of LES. The high productivity investment of annuals is better than the high defense investment of perennials for adapting to the special habitats in the WLFZ. These results indicated that different functional plants in the WLFZ of the TGR under different hydrological regimes can adopt different strategies by weighing the associations and trade-offs between their economic traits.

为验证一种浮游植物快速浓缩固定方法——滤膜浓缩法的可靠性,采用"鲁戈氏液固定沉降法"和"滤膜浓缩法"同时鉴定了不同浮游植物浓度梯度水样,并进行了对比分析,结果表明:鲁戈氏液固定沉降法与滤膜浓缩法整体上均鉴定出7门,32属,但不同梯度上滤膜浓缩法鉴定出的浮游植物种类较多.两种方法门水平上除裸藻门(P＜0.05)外丰度均无明显差异(P＞0.05),属水平上相对丰度99％以内的浮游植物均无明显差异(P＞0.05),即无论是门还是属水平上,滤膜浓缩法对浮游植物丰度的鉴定是可行的.采用两种方法得到的不同梯度下藻密度拟合方程斜率差异较小(P＞0.05)且相关性显著(R2=0.958,P＜0.01),但滤膜浓缩法鉴定出的浮游植物细胞密度更大.整体来看,滤膜浓缩法得到的藻类鉴定结果与鲁戈氏液固定沉降法基本一致.

中国已建各类水库近10万座,水库建设改变了原河流水动力条件,影响了水体物质场、能量场、化学场和生物场,究竟是"削减了水体净化功能"还是"强化了水体去污能力"目前尚不明确.本文系统总结了开放水体脱氮过程研究进展,主要包括:(1)厌氧反硝化(Denitrification)、厌氧氨氧化(Anaerobic ammonium oxidation)、好氧反硝化(Aerobic denitrification)和厌氧甲烷氧化(Anaerobic methane oxidation)等是目前开放水体脱氮的4个典型过程;(2)潜流带、沉积物、溶解氧极小层及悬浮颗粒等是开放水体脱氮的主要发生区域;(3)溶解氧、碳氮比、硝酸盐浓度、温度、pH值是影响开放水体脱氮效率的直接因素.建议通过开展"出入库氮形态持续观测及氮负荷平衡计算"、"水库不同载体脱氮机制原位研究方法构建"、"水库脱氮机制及氮移出通量研究"和"自然河流与水库脱氮效率对比研究"等方面的研究来回答"水库强化水体脱氮能力"这一科学假设,以期为发掘水库的脱氮除污功能、深入认识水库的生态环境影响提供一个新的研究思路.

为探究梯级水库建设下澜沧江流域电导率和浊度变化规律,以澜沧江干流和梯级水库作为研究对象,在2016年10月、2017年2月、2017年6月、2018年1月进行水质参数监测.通过对澜沧江流域电导率、浊度等指标进行监测分析,以表征梯级水库建设对澜沧江水环境的累积效应.由Pearson相关性分析结果表明,电导率与浊度相关性显著.空间上,自上游至下游,自然河段电导率沿程逐步下降,水库河段电导率缓慢降低,其中在大型水库坝前坝后波动较大;浊度自上游至下游先上升后下降,自然河流段先增高后降低,水库河段浊度变化范围较小.时间上,平水期电导率因汛后富集作用整体上高于其它时期,自然河段丰水期电导率最低,水库河段变化范围与趋势几乎一致;自然河段丰水期浊度显著高于其他时期,水库河段在不同时期沿程总体在90 FNU以下.梯级水库建设使流速减缓,电导率和浊度累积效应明显.小湾水库不同时期浊度垂向变幅在10 FNU以内,电导率因水体滞留时间增大随水温出现分层现象;功果桥水库、苗尾水库不同时期水体滞留时间短,浊度垂向变幅较小湾水库大,垂向掺混使电导率变幅较小.

In the mainstream of the Lancang River, eight cascade dams have been constructed. In order to find the effects of the cascade reservoirs on the transformation of nitrate (NO3-N) and ammonium (NH4-N) in pore water of sediments, a field survey was carried out both in the upper natural river reach (NRR) and cascade reservoirs reach (CRR) of the Lancang River from January 10 to 20, 2018. The results indicated that (1) in the NRR, NO3-N concentrations in sediment pore water were higher than those in the CRR, whereas the total nitrogen (TN) and NH4-N were significantly lower; the diffusion fluxes of NH4-N from sediment to overlying water varied from -0.180 to 0.049 mg center dot(m(2)center dot d)(-1), and the diffusion fluxes of NO3-N varied from 0.012 to 0.098 mg center dot(m(2)center dot d)(-1). (2) in the CRR, the NH4-N concentrations in sediment pore water were much higher than those in the overlying water, but the NO3-N concentrations in the overlying water were much higher; the diffusion fluxes of NH4-N from the sediments to the overlying water varied from 0.161 to 1.561 mg center dot(m(2)center dot d)(-1), but the NO3-N diffused downward from the overlying water to the sediments and the diffusion fluxes varied from -0.011 to -0.223 mg center dot(m(2)center dot d)(-1). It was concluded that the cascade reservoirs could increase the NH4-N concentration and inversely decrease the NO3-N concentration in the sediment pore water, which meant that the risk of the nitrogen release from the sediment in the cascade reservoirs was much higher than that in the natural river.

通过对已建水库河流的沉积物磷形态与未建水库河流进行对比,揭示建有水库河流与自然河流沉积物磷形态的差异,并分析其差异的原因.结果发现:怒江、澜沧江自然河段TP含量分别在510.68～624.61 mg·kg-1、528.79～629.40 mg·kg-1之间变化,澜沧江水库段383.50～1044.13 mg·kg-1之间变化.沉积物6种磷形态中,自然河道段Ex-P、Fe-P、Al-P、OP、Ca-P、Res-P含量分别在0.87～5.02 mg·kg-1、19.13～44.4 mg·kg-1、8.81～33.97 mg·kg-1、73.74～142.75 mg·kg-1、325.22～493.51 mg·kg-1、34.67～76.84 mg·kg-1之间变化;而澜沧江水库段Ex-P、Fe-P、Al-P、OP、Ca-P、Rest-P含量分别在0.72～4.41 mg·kg-1、28.68～81.01 mg·kg-1、11.52～377.03 mg·kg-1、40.61～160.78 mg·kg-1、46.91～349.83 mg·kg-1、23.49～92.84 mg·kg-1之间变化.与自然河道相比,水库段沉积物Fe-P、Al-P含量上升,Ca-P(除坝下沉积物含较高外)在库区的含量下降.水库段沉积物Fe-P、Al-P含量上升,其可能的原因是沉积物中的Ca-P释放产生的磷酸盐,较深部位沉积物层的铁磷矿物还原溶解释放溶解磷酸盐以及较小粒径的沉积物吸附水体中的磷酸盐与沉积物中铁铝的(氢)氧化物结合而沉积下来.

以澜沧江流域功果桥库区消落带沉积物为研究对象,研究了持续干燥状态下磷形态和等温吸附变化特征.结果表明:持续干燥对磷和铁形态有显著影响,弱吸附态磷(NH4Cl-P)、铝结合态磷(NaOH-rP)无机磷(IP)和结晶度较高的碳酸盐铁(CarD-Fe)含量增加,而可还原态磷(BD-P)、聚磷/有机磷(NaOH-nrP)和还原铁氧化物(Ox-Fe)含量减少;沉积物等温吸附特征也有显著变化,最大吸附磷酸盐总量(Qmax)和吸附系数下降,表明重复短暂的湿润和干燥周期会导致磷的沉积亲和力不断下降,从而增加沉积物内源磷向水体释放的潜在性.

Water quality in the Three Gorges Reservoir and all its tributaries is of critical significance for the ecological and economic development of the middle and lower Yangtze River watershed.The construction of the reservoir impoundment has caused higher water surface elevation, slower current velocity, and even backflow in its main tributaries, including the Xiangxi River.More nutrient species related to nitrogen and phosphorous are being conveyed to the water body and retained in the river's bay region much longer than previously, leading to more frequent eutrophic events such as algal blooms, and significantly threatening the downstream water quality.This study focuses on the nutrient species levels, statistically analyzing the available data to determine the effect of backflow and estimate the variation in algal levels, developing mass balances for the water budget and important contaminants, and calculating the ratio of total nitrogen to total phosphorus.Based on the data from the eutrophication processes happened in the Xiangxi River during the period from January to November 2010, total nitrogen is the limiting factor.The amount of water accumulated in the Xiangxi River was 1.108×10 10 m 3 , and the water level rose by 5.78 m from January to November 2010.Most of the phosphorus and ammonia in the river came from non-point source pollution.The results will be used to help verify and calibrate variations in the water flow rate and the associated point source and non-point source pollution.Since the Xiangxi River is a representative tributary of the Three Gorges Reservoir, the research method developed and conclusions drawn will provide a valuable reference for eutrophication investigations of other tributaries.

The ecological problems due to reservoir construction are causing unprecedented concern. To reveal the differences in organic carbon distribution characteristics and sediment sources of total organic carbon (TOC) between the old and new reservoirs, water samples, and sediment samples from reservoirs constructed in the three different periods of Miaowei, Gongguoqiao, and Dachaoshan were collected in November 2017. The temperature (T), dissolved oxygen (DO), TOC, redox potential (ORP), total nitrogen (TN), and total phosphorus (TP) of the water samples were measured. The isotopes 15N and 13C were used as indicators with IsoSource software to analyze the contributions of TOC sources and their source materials to the corresponding reservoir sediments, in order to explore the carbon cycle mechanism and evolution mode of reservoir. The results showed that the average concentrations of organic carbon in the waters of the Miaowei, Gongguoqiao, and Dachaoshan Reservoirs were 0.95 mg·L-1, 1.97 mg·L-1, and 4.64 mg·L-1, respectively. The range of organic carbon content in the corresponding sediments was 4.41-81.63 g·kg-1, 18.30-28.42 g·kg-1, and 9.16-14.46 g·kg-1, respectively. The cascade construction of the reservoirs resulted in a difference between the sediment sources of the new and old reservoirs and the surrounding recharge area, meaning that the TOC of the new and old reservoirs were significantly different. For the TOC of waterbodies, the difference between the thermodynamic state of water and dissolved oxygen indirectly affects the distribution trend of TOC. The sediments mainly reflect the influence of source elements, that is, the ability of the sedimentary environment to preserve organic matter was the main cause of the vertical distribution of DCS, MV, and GGQ sediments. In the evolution mode of cascade reservoir, the research shows that it can be preliminarily set as three stages. Firstly, due to the short age of MV, it is in the first stage and mainly accumulates the TOC from the upstream. GGQ is longer than the age of MV, and it is mainly used to decompose the upstream TOC, so it is defined as in the second stage. Finally, as an old reservoir, DCS mainly accumulates TOC sources around the reservoir, which can be regarded as the third stage.

可靠的能量消耗估算可以更好地衡量鱼体在上溯过程中的能量分配方式,为鱼道水力设计提供依据,实现鱼道过鱼的高通过率.为探究鲢(H ypophthalmichth ys molitrix)幼鱼运动过程中游泳行为和能量消耗的关系,利用丹麦Loligo Systems公司生产的鱼类行为视频跟踪系统,对24尾鲢幼鱼进行了室内游泳行为实验.采用流速递增法测得鲢幼鱼的活动代谢率,水体溶氧量由每个流速工况下等时距读取,静水条件下通过AutoRespTM测定水体溶氧变化值,计算标准代谢率;利用水槽上方架设的摄像头(25帧/s)记录鱼体运动行为,连接uEye Cock-pit程序观测鱼体运动情况,采用LoliTrack进行运动行为分析,获取鱼体运动行为学参数.结果 表明,鲢幼鱼的游泳速度与摆尾频率(TBF)呈显著正相关关系,其耗氧率(Mo2)与摆尾频率(TBF)的拟合方程为Mo2 =318.3+1.04TBF2.87 (R2 =0.99,P＜0.001),拟合指数值为2.87,且摆尾频率的幂指数越大,表征鱼体游泳效率越低.实验测得鲢幼鱼的标准代谢率(SMR)为(284.47±30.75)mg/(kg·h),耗氧率方程得到的标准代谢率拟合值为318.3mg/(kg·h),与实测值较为接近;通过建立活动代谢率(AMR)与鱼体重量(M)及游速(U)的关系,得出鲢幼鱼生物能量模型AMR=10.39M012U039(R2 =0.95,P＜0.001).生物能量模型的建立,可以为鱼道不同过鱼目标的水力设计提供参考.