桉树人工林区水库底泥氮、磷和有机质时空分布特征

为探究桉树种植对其林区水库底泥理化特性的影响及水库内部营养盐和有机质的运移转化机制,针对广西南宁市桉树人工林区那降水库,测定了底泥的含水率、总氮、总磷、总有机碳和有机质,分析探讨了底泥氮、磷和有机质的分布特征及氮、磷与有机质之间的相关关系,并评价了底泥的肥力状况。研究结果表明:那降水库底泥氮、磷和有机质的含量随其深度的增加而降低; 8月底泥氮、磷平均质量比分别为2 199 mg/kg和256 mg/kg,均略高于12月的平均质量比(1 994 mg/kg和230 mg/kg),主要在于夏季水库形成水温分层,延缓了底泥营养盐释放;桉树培育期施用的肥料是底泥氮、磷的重要来源,农药及砍伐后的残枝落叶是底泥有机质的主要成分;底泥有机指数远大于0. 05,属于Ⅲ级肥污染状态;桉树对林区水体的氮、磷及有机质的贡献较其他树种更为显著,是林区水库底泥肥污染的重要原因之一。     

密云水库总氮现状及出入库路径解析研究

近年来,密云水库总氮浓度持续升高,通过对2020—2022年3年间总氮浓度的变化规律的研究,分析了水质与水量之间的响应关系。结果表明,库区总氮浓度从2020年的1.31 mg/L到2021年的1.37 mg/L,再到2022年的1.98 mg/L,呈现出逐年升高的趋势。从河流入库和大气沉降两方面研究核定了总氮输入总量。潮河3年的入库平均浓度为6.63 mg/L,白河3年的入库平均浓度为2.77 mg/L,潮河的入库总氮浓度显著高于白河;库区总氮干沉降主要以气态干沉降为主,占比69.1%。从鱼类总氮、水库放水以及水体自净等3个方面核算了总氮输出总量。鱼类总氮量年平均为56.59 t;水库放水总氮量年平均为1 012.98 t;微生物累计脱氮量年平均为1 956.72 t。研究结果为密云水库总氮防控与政策制定提供参考依据。     

柳堰集水库渔光互补工程对水环境影响的数值模拟研究

针对渔光互补工程对水环境的影响缺乏精准量化研究的问题，构建了适用于柳堰集水库的水动力-水质-水生态-工程耦合数值模型，模拟了2020年8月自然现状和渔光互补工程实施后库区水温、化学需氧量、溶解氧、总磷、总氮、叶绿素a的质量浓度时空分布，并计算了水体富营养化指数。结果表明：渔光互补工程实施后，柳堰集水库的水温、溶解氧和叶绿素a质量浓度分别下降了0～6℃、0～0.02 mg/L和0～0.000 5 mg/L,化学需氧量质量浓度上升了0～10 mg/L;总磷、总氮质量浓度变化趋势在光伏板下伏水域和未布设光伏板水域呈现较大差异性，光伏板下伏水域总磷质量浓度升高了0～0.814 mg/L,总氮质量浓度降低了0～0.125 mg/L;各水质指标在渔光互补工程实施前后的差异随时间推移逐渐减小，入汇口水体富营养化程度显著下降，中央库区灌溉取水口水体富营养化指数提高了5.61～16.00。     

平原型水库水体热分层的水质响应特征与水质改善成效

针对平原型水库热分层特征及其对水质的影响问题,采用CE-QUAL-W2模型建立了立面二维水温模型,模拟了2018年全年的水温变化特征,三个率定断面的绝对平均误差分别为0.53℃、0.35℃和0.14℃。基于模拟结果和监测数据,分析了水库热分层的季节性变化及水质响应特征。在轴流泵混合曝气技术的基础上提出了一种移动式扬水器用以增加水库底层DO浓度,基于监测数据初步分析了移动式扬水器对垂向水质的改善效果。结果表明:水库全年呈现单循环混合模式(5月-11月为分层期,12月-4月为混合期),夏季形成稳定的热分层结构,底层形成厚度约为8m的缺氧区(DO浓度低于2mg/L);厌氧环境下底层污染物(铁、锰、总氮、总磷、COD、氨氮等)的释放量远大于表层和中层,底层水质较差;移动式扬水器能够有效提高底层DO含量,弱化热分层结构(工作中心的DO浓度由0.2mg/L提高至0.8mg/L,温跃层厚度减少了4m)。     

寒旱区某浅型水库热分层特征及供水影响

文章连续监测不同深度水质变化趋势,阐明寒旱区某浅型水库热分层特征。在夏季水库出现热分层现象,水深较深的库区形成活性反应带,底层溶解氧达到缺氧区阈值2mg/L以下,铁和锰超标,水库内源污染是形成活性反应带的重要因素。描述了水生动植物代谢活动、动植物残体及排泄物、沉积物带来的内源污染因素,水体循环较慢是出现热分层的重要条件。提出了浅型水库热分层现象对供水安全的影响,为保证供水安全提供了科学依据和防治措施。     

万家寨水库水环境特性分析

作为山西省的重要水源地,万家寨水库水环境质量对于山西省的供水安全具有重要意义。通过建立非结构单元的水环境数学模型,对现状情境下万家寨水库库区进行水动力过程模拟,分析最不利水文条件下区域内水环境特性。结果表明,水动力场显示,上游流量的大小对库区水体自净能力影响明显,研究区域水力停留时间最短出现在丰水年夏季,最长出现在枯水年冬季;在固定源连续排放下,枯水期、平水期、丰水期3种水文条件下,COD最大允许排放浓度分别为426、310 mg/L与252 mg/L;在枯水期、平水期、丰水期内,下游3个控制断面COD浓度均可达到二类水质标准时,污染物COD的水环境容量分别为14 060、15 959 t/d和18 137 t/d。     

龙滩水电站库区蓄水后垂向水温水质分布预测

采用垂向一维数学模型对在建龙滩水库蓄水后水温和水质进行预测，并采用类比调查等方法对模型中各项参数进行了估计．预测结果表明，龙滩水库蓄水后水温随水深逐步降低，多年平均表层水温为19．9℃，库底水温约为8℃,下泄水温年变幅减小，与天然河道水温相比，降低较大，但与天生桥水库建成后河道水温相比，则差别明显减小．水质分布也存在明显分层现象，表层年内变化较大，随着水深增加，变化逐渐趋缓．水库多年平均表层DO约为8．65mg／L，底层约为4．8mg／L，处于低氧状态。库区形成后BOD5浓度较低，表层和底层多年平均分别为0．46mg／L和0．1mg／L，与建库前天然河道相比有明显改善．下泄水质与自然河道水质对比分析发现，BOD，浓度在建库前后有明显的差异，由1．6mg／L下降到0．3mg／L左右，而DO浓度变化甚小。     

沙源区水库氮磷营养盐时空分布与相关性分析

为揭示典型沙源区水库水体氮磷等营养盐时空分布特征和相关性,以大河口水库为研究区,布置5个监测断面,对水库水质进行采样分析,结果表明:受风沙降尘、上游河流水质和库区底泥影响,在时间分布上,4月水体解冻至6月,各检测断面TN、TP等营养盐浓度总体呈明显持续升高趋势;在空间分布上,从入库口A-A断面和B-B断面至出库EE断面TN、TP浓度逐渐降低;在垂向分布上,水库表层水体和底层水体氮磷浓度高于中层水体;TN、TP在水库中的变化规律一致,呈一定比例存在于水库中;温度是影响TN、TP浓度变化的重要因子;藻类的生长对TN和TP起抑制作用;水库中TN、TP的变化与DO含量基本无关。     

崂山水库浮游植物的季节变化及水体营养状态

为掌握崂山水库水质状况,2008年对崂山水库水体理化指标、浮游植物群落结构和细胞密度进行了监测。监测结果为:共检出浮游植物7门45属62种,其中种类最多的是绿藻和硅藻,分别占总种数的48.39%和27.42%。浮游植物群落结构季节变化明显,3月份硅藻种类最多,7月、8月和10月绿藻种类最多。库区优势种为鱼腥藻(Anabaena Bory.)、实球藻(Pandorina morum Bory.)、隐藻(Crytomonas Ehr.)、小环藻(CyclotellaKtz.)。水库浮游植物的四季平均细胞密度为12.8×105个/L,8月份最高,达到40.5×105个/L。叶绿素a的质量浓度年均值为7.05 mg/m3,综合营养状态指数为50.6。总体来看,水库水体已经呈现中营养向轻度富营养化转化的趋势。     

潘家口水库氮与磷营养盐的时空变化及滞留效应分析

潘家口水库是华北地区的重要水源,对保障区域供水安全发挥着重要作用。本文以该水库为研究对象,分析了建库以来水库氮、磷营养盐的时空变化特征、滞留效应。结果表明：建库以来水库TP浓度呈上升趋势,最高达到0.37 mg/L;库区TN、硝酸盐的浓度较高,年际变化小,近15年平均浓度分别为4.4 mg/L、3.5 mg/L,氨氮浓度基本低于0.5 mg/L。库区氮、磷以滞留为主,其浓度主要受来水影响;磷的滞留效率呈下降趋势,近5年滞留效率为-6%;氨氮滞留效率一直较高,近5年滞留效率为72%;硝酸盐滞留效率呈增加趋势,近5年滞留效率为20%,硝酸盐和磷的滞留效应呈显著的负相关关系。结合垂向水质监测的分析表明,近年来库底存在内源污染的显著释放和反硝化脱氮。潘家口水库库底沉积物污染严重,内源污染将是未来水库水质恶化的潜在风险。为了保证水库的供水水质,抑制库区内源污染的释放,建议水库尽量保持高水位运行。     

保山北庙水库集水区5种森林类型枯落物持水特性研究

利用样方调查法、烘干法、浸泡法分析了云南省保山市北庙水库集水区纯云南松、纯人工桉树林、混交林Ⅰ(云南松+桉树混交林)、混交林Ⅱ(云南松+华山松+杉木+青冈栎混交林)和纯华山松5种森林类型枯落物的持水能力。结果表明:5种森林类型枯落物蓄积量都较小,最大为7.27 t/hm²,最小为4.51 t/hm²;枯落物未分解层和半分解层持水量随着浸泡时间增加,在8 h时平均持水量分别为5.22,5.83 t/hm²,24 h时分别为5.69,6.26 t/hm²;吸水速率随着浸泡时间减少,在8 h时平均吸水速率分别为0.65,0.73 mm/h,到24 h时分别为0.24,0.26 mm/h,且均是半分解层＞未分解层;纯华山松和混交林Ⅱ 2种森林类型枯落物持水性能优于其他3种森林类型。研究结果可为水源区植被恢复、选择最佳树种、合理配植森林类型、森林涵养水源提供科学依据。     

Physical regimes and nutrient limitation affecting phytoplankton growth in a meso‐eutrophic water supply reservoir in southeastern Brazil

The water‐mixing regime, light availability, nutrient limitation and trophic state were evaluated for the Duas Bocas Reservoir (DBR; Espírito Santo State, southeastern Brazil), a small (0.51 km²), shallow (z_max < 10 m) water supply reservoir located in a conservation area. Monthly water sampling was conducted for the lacustrine zone (z_max = 10 m) next to the water withdrawal tower, during one hydrological cycle (October 2002 to September 2003). Water samples were taken at four depths in this area, including subsurface, Secchi depth, euphotic/aphotic boundary and near the bottom of the lake. The variability of the reservoir’s limnological features defined two periods. Period 1, comprised of the summer months (October to April), was characterized by strong thermal stratification, nutrient limitation in the mixing layer, a metalimnetic biomass maximum and anoxia and high nutrient concentrations in the hypolimnion. Period 2, comprised of the winter months (May to September), was characterized by overturn events during which the phytoplankton population experienced light limitation. The observed water‐mixing regime was characteristic of warm monomictic system, presenting atelomixis, the incomplete vertical mixing of stratified water masses. The average total phosphorus and chlorophyll‐a concentrations suggested a meso‐eutrophic water system. The nutrient concentrations exhibited nitrogen and phosphorus limitation, suggesting that nutrients, rather than light, limit or regulate the phytoplankton biomass in the DBR for most of the year.     

三河口水库消落带植物水解氮磷释放特征研究

以三河口水库5种消落带优势植物青蒿、艾、醴肠、菵草、酸模叶蓼的地上茎叶部分为样本,库水为实验原水,进行室内水解模拟实验。通过测定上覆水的基本水质指标及氮磷养分浓度,探明消落带植物经过水解后,对水体水环境的影响及不同形态氮磷养分的释放特征和负荷。结果表明：5种植物水淹后均引起上覆水颜色加深且产生异味,pH值下降,浊度增大,电解率增大,溶解氧降低;氮、磷养分得到释放,总氮和总磷的平均释放量分别为4.06和0.78 mg/g,其中颗粒态氮、磷相应占总氮和总磷的43.2%和36.2%;在水库的蓄水初期（30 d）,消落带植被向水体释放的氮、磷负荷可达40.4和7.6 kg/hm²,这些将对三河口水库的水环境安全造成影响。     

Behavioural interactions between prey (trout smolts) and predators (pike and pikeperch) in an impounded river

Movements of radio‐tagged pike Esox lucius (L.), pikeperch Stizostedion lucioperca (L.) and outward migrating sea trout smolts Salmo trutta (L.) were studied in a shallow Danish reservoir to obtain information of predator–prey interactions between these species. Twenty pikeperch (55–74 cm) and 19 pike (52–72 cm) were tagged. Female pikeperch spent more time near the outlet sluice during the smolt run (May) than at other times of the year, apparently actively hunting the smolts delayed in this area. In contrast, male pikeperch did not seem to participate in the smolt predation but remained stationary during the smolt run, presumably guarding their nests. Most tagged pike were present at the spawning grounds during the peak of the smolt run, where they had little chance of smolt encounter. Twenty migrating trout smolts were radio‐tagged in the river upstream of the reservoir. Ten of these were located in the vicinity of the outlet sluice at least once, but were unwilling or unable to find and enter the sub‐surface outlet sluice. Only one tagged smolt left the reservoir. After 1–12 days in the reservoir, the remaining smolts were eaten by pikeperch or pike and the results indicate that female pikeperch and few female pike have adjusted their behaviour to predation on smolts during the smolt run. The smolt predation in this man‐made reservoir is higher than in natural lakes, probably due to the changed physical environment and introduced predators, such as pikeperch. The outlet sluice practice and the temporal overlap between smolt run and predator‐spawning may be key factors in smolt survival. Copyright © 2000 John Wiley & Sons, Ltd.     

Removal of the Invasive Shrub,Lonicera Maackii,from Riparian Forests Influences Headwater Stream Biota and Ecosystem Function

Riparian forests and streams are interlinked by cross‐system subsidies and alterations of the terrestrial environment can have substantial effects on aquatic biota and ecosystem function. In the Midwestern USA, the exotic shrub Lonicera maackii (Amur honeysuckle) has successfully invaded many riparian habitats, creating near‐monocultures in some locations. This terrestrial invasion has strong potential to modify cross‐system subsidies and impact stream ecosystems. We removed L. maackii from a riparian forest to assess impacts on the aquatic environment. In August 2010, removal occurred along a 150 m stream reach, 10 m downstream of a non‐removal reach, before natural leaf senescence. Over 74 days, in‐stream leaf litter [organic matter (OM)] was collected weekly from plots located in riffles (five/reach). Benthic algal biomass, above stream canopy cover, and macroinvertebrate density were measured for 18 months. L. maackii removal was associated with decreased canopy cover and a significant increase in total in‐stream leaf OM in early autumn (P < 0.05). Removal also differentially influenced the timing and abundance of specific leaf litter genera within the stream (P < 0.05). Macroinvertebrate density was significantly higher in the removal reach, especially during autumn 1 year after removal (P = 0.0294). In both reaches, macroinvertebrate density peaks lagged behind benthic algal biomass peaks. In summary, the removal of an invasive riparian shrub influenced the timing, deposition, quality and abundance of leaf litter habitat into a headwater stream, ostensibly driving bottom‐up effects on aquatic primary producer biomass and the macroinvertebrate community. Copyright © 2014 John Wiley & Sons, Ltd.     

湖南省水库与干旱情势空间匹配关系研究

根据湖南省地质、地形等条件,以县域为单元将湖南省划分为9个区域,对省内14 000多座各类型水库开展空间统计,分析了水库空间分布规律,并采用SPI-3指数法计算得到4-9月重旱及以上干旱频率的空间分布,对比研究了水库分布与干旱的空间匹配关系。结果表明：湖南省水库分布具有明显的空间分异特征,丘陵区水库数量密度一般要大于山地区,但受大型水库不足的影响,库容密度一般要小于山地区。洞庭湖平原腹地水库密度极低,而外围岗地区则拥有全省最大的水库分布密度。不同分区水库供水能力与人口、耕地的匹配关系也有很大差异。湘东南罗霄-南岭山地区单位面积兴利库容和人均兴利库容最大分别可达54 397.32 m³/hm²和3 286.53 m³,而在湘中南岩溶丘陵区、洞庭湖区等地区则分别不大于3 450 m³/hm²和210 m³。湖南省水库的空间分异特征主要受地质、地形等地理条件控制,山地区水库规模大、数量少,而丘陵区水库小、数量多。总体上看,湖南省水库供水能力与干旱的空间分布存在明显的失衡错位,如衡邵盆地不仅年均降雨量少、重旱频率高,而且水库供水能力也处于全省较低水平,再加上岩溶区“保水难”的特性,该区成为省内干旱情势最为严重的地区。     

Ecology of an estuarine mysid shrimp in the Columbia River (USA)

The estuarine mysid, Neomysis mercedis, has colonized John Day and other run‐of‐the‐river Reservoirs of the Columbia River, over 400 km from the estuary. In John Day Reservoir N. mercedis numbers peaked (2 m^?3) in August in areas near the dam in association with lower water velocity and softer bottom than at the upstream sampling sites. Neomysis broods were primarily released in late spring and early fall. Gut content analysis showed that Neomysis feeds mostly on cladoceran zooplankton and rotifers in John Day Reservoir. Diel vertical migration was documented, with daytime distribution restricted to the bottom and preferentially to the soft‐textured sediments in the deepest areas. Common pelagic fishes in the reservoir, especially juvenile American shad (Alosa sapidissima) and chinook salmon (Oncorhynchus tshawytscha), are daytime zooplankton feeders that cannot prey on Neomysis owing to mysid diel vertical migration. Thus, Neomysis has become an important food web component in John Day Reservoir. We also collected N. mercedis further upstream in Lower Granite Reservoir, where another estuarine crustacean, Corophium salmonis, also is reported, underscoring the need to better understand the role of these estuarine invertebrates in the trophic ecology of the Columbia River. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of selective water intake on the oxygen regime of a stratified reservoir

Conclusions  

Characterization of water quality in a small hydropower plant reservoir in southern Brazil

The construction of large reservoirs can cause profound environmental changes. Reduced water flow, increased water residence time, thermal stratification, increased sedimentation rates and decreased dissolved oxygen concentrations are examples of such changes. These changes can affect water quality and the biota in the environments adapted to the natural conditions of a river. Small reservoirs developed in conjunction with hydropower plants, however, could reduce the degraded water quality. This study focuses on characterizing water quality in a small hydroelectric reservoir. The study reservoir has an area of 1.4 km² and a short water retention time. The Monte Claro Hydroelectric Power Plant is part of a complex consisting of three plants on the Antas River in the north‐west of Rio Grande do Sul state, Brazil. The reservoirs associated with these plants are operated as run‐of‐the‐river facilities. Monitoring results obtained by CERAN, the Energetic Company of Antas River (Companhia Energética Rio das Antas), were used to evaluate the reservoir water quality. Three samples were collected seasonally (spring, summer, autumn and winter) in the area of influence of this plant following the filling of the reservoir (2005–2008). The examined water quality parameters were electrical conductivity, colour, turbidity, alkalinity, pH, biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus, dissolved oxygen, sulphate, nitrate, nitrite, ammonia, suspended and dissolved solids, chlorophyll‐a, total and faecal coliforms, water temperature and Secchi depth transparency. The results were interpreted using an index of water quality, Trophic State Index, reservoir water quality and CONAMA Regulation 357/05 (Brazilian legislation). Based on these analyses, no significant changes were exhibited in the water quality of the reservoir from the hydroelectric plant operation.     

溪洛渡-向家坝-三峡梯级水库水温分布特性

梯级水库蓄水运行后,改变了河流的天然水流情势和水体的年内热量分配,水库内的水温分布特性随之变化。为了解溪洛渡-向家坝-三峡梯级水库蓄水运行后河道水温分布特征,对梯级水库沿程19个断面水温进行了观测,并根据观测资料系统地分析了梯级水库进出库水温和沿程水温分布,以及垂向温度分布变化情况。研究结果表明:溪洛渡、向家坝、三峡梯级水库的下泄水温在降温季节略有增加,在升温季节略有下降,形成了"高温不高,低温不低"的平坦化现象;溪洛渡和向家坝水库坝前区域在垂向上均出现明显的温度分层,而三峡水库近坝区的温度分层现象在梯级水库运行后明显减弱,近几年表层和底层水温相差最大值仅为2.5℃。研究结果可为梯级水库联合调度、水生态研究、水库水温数学模型验证等提供参考。