乌江中上游梯级水库氮磷滞留效应

目前世界河流普遍面临大规模筑坝拦截现状,原有河流自然形态逐渐向湖泊化转变,研究河流中氮磷营养盐物质的输送通量与滞留效应成了评价水坝水环境情况的关键问题。本研究详细调查了位于乌江流域中上游的洪家渡、东风和乌江渡3座水库的氮磷营养盐分布特征、输送通量及滞留效应。结果表明,洪家渡、东风和乌江渡3座水库TN年平均实际滞留率分别为20.2%、36.0%和-21.1%,TP年平均实际滞留率分别为5.4%、56.5%和-84.9%。3座水库因受到水文条件的不同、建库时间的长短和人为输入等因素影响,氮磷营养盐表现出不同的滞留现象及时空差异性。乌江渡水库氮磷营养盐的年平均滞留率因网箱养鱼的影响表现为负值。东风水库存在明显的氮磷滞留效应。洪家渡水库因受早期淹没植被再降解过程的影响,氮磷营养盐实际滞留效应弱于东风水库。     

太湖典型菜地土壤氮磷向水体径流输出与生态草带拦截控制

农业面源氮磷输出是导致太湖流域地表水富营养化主要原因之一,查明该地区农田土壤地表径流氮磷向水体迁移形态与通量,并实施径流控制,对水体富营养化治理具有重要现实意义。蔬菜地是太湖流域重要的农业种植方式。通过设置野外径流小区,观测了春夏季蔬菜地土壤氮磷径流输出,并探讨了生态拦截草带对径流中不同形态氮磷拦截效果。结果表明,2004年10月25日至2005年8月17日,菜地土壤氮磷径流输出总量分别为3 010.9和695.0 g.hm-2;其中颗粒态为主,分别占64%和75%。可溶态氮中,NH4 -N为主,占50%,可溶态磷中H2PO4-为主,占87%。生态拦截草带对径流氮和磷拦截效率分别为42%~91%,30%~92%。生态草带对颗粒态氮磷拦截效率大于可溶态。拦截草带可有效地控制蔬菜地土壤氮、磷通过径流向水体迁移。     

水文气候波动下云南太平水库硅藻群落演替的长期特征

在区域气候变暖的背景下,干旱事件引起的水位频繁波动以及流域开发导致的污染物输入均可以直接威胁水库的生态安全。本研究以云南省太平水库为对象,通过对沉积物的物理(粒度、烧失量)、化学(碳、氮元素)、生物(硅藻群落)等代用指标的分析,并结合监测数据和调查资料,重建了该水库1937—2018年的生态环境变化过程,并识别了硅藻群落的演替特征及其环境影响因子。粒度结果指示,太平水库在筑坝期间(1956—1984年)水动力逐渐增强,而后水动力条件持续减弱,与文献记录的水文调控历史基本一致。总氮、总碳和有机质含量较为一致地记录了水库建设期间水体营养水平的下降、水库建成后初级生产力和内源有机质的上升过程。硅藻群落呈现出“浮游种-底栖种-浮游种”交替占优的演化模式。驱动太平水库硅藻群落演替的主要环境因子为气候变化、水动力条件和营养水平。在气候长期变暖的背景下,严格控制外源营养输入并合理开展水文调控是维持水库水体生态健康和环境安全的重要前提。     

水库磷收支及其调控措施研究进展

磷是主要的富营养化限制性因子,其收支途径和调控措施的研究是水库生态安全的重要保障.为推动水库磷的系统研究,进一步完善磷调控体系,本文归纳了水库磷的收支途径,分析了不同因素对磷收支的影响,并对常规调控措施进行了梳理.水库磷输入的主要来源包括上游河流、地表径流、生活生产污染、养殖投入、大气沉降和底泥释放.其中上游河流的输入是水库磷最大的来源.磷主要的输出途径为泄洪或放水,并受不同排水方式的影响.另外生物收获也会输出部分磷.水库磷收支平衡受水库功能、水文条件和水体理化性质等因素的影响,不同季节和地域的收支情况差异很大.在磷的调控治理上,人工湿地、前置库、底泥疏浚和生物操纵法是目前采取的主要措施.为有效去除磷,需根据水库不同生态特性和水质管理目标,选择或结合多种不同的调控方式.因此,未来的研究应突出水库生态特性,进一步对水库磷收支及其影响因素进行系统分析,并开展水库磷收支与其他营养物质之间影响关系的研究,在此基础上构建科学完善的管理体系,是有效削减水库磷的根本保障.     

工程化循环水养殖池塘的氮磷收支研究

为了探寻更清洁高效的养殖模式,研究将淡水池塘循环水养殖系统进行了改良,对5个月试验周期内池塘水体理化指标和氮磷收支情况进行了分析。结果显示,池塘水体的理化指标呈波动性变化,试验结束时总氮、总磷浓度分别为4.85和1.04 mg/L,总氮浓度符合淡水养殖尾水排放二级标准。饲料和底泥是池塘氮磷输入的主要来源,分别占池塘氮元素输入量的50.6%和43.7%,磷元素输入量的49.4%和46.9%;底泥积累是池塘氮磷输出的主要途径,分别占池塘氮磷元素输出量的53.3%和78.7%。试验池塘对氮磷的利用率分别为65.2%和16.6%,其中鲤对氮磷的利用率显著高于其他鱼类(P<0.05),鲢、鳙对磷的利用率无显著差异(P>0.05)。研究表明,改良后的池塘循环水养殖系统有效降低了营养负荷,提高了养殖生物的氮磷利用率,减轻了养殖尾水对周边环境的影响,兼顾生态与经济效益,是一种成本较低且可持续发展的池塘养殖模式。     

高州水库氮磷营养盐变化特征及水质管理对策

通过2012-2013 年对广东省高州水库氮磷营养盐的趋势变化进行分析, 探讨了水库中氮磷浓度的变化特征,并从水库管理与水动力学两方面对水库水质管理对策进行了讨论。研究结果表明: 高州水库总氮、总磷浓度均表现为丰水期高, 说明受强降雨的影响, 农业面源污染携带大量的氮磷随地表径流进入库区, 致使库区氮磷营养盐含量升高。其次, 入库河流是库区氮磷营养盐的主要来源。氮磷比分析结果表明, 高州水库流域内部分水体在时空上处于氮限制与磷限制交替出现的状态, 且氮磷比与总磷呈现显著地正相关, 进一步反应了高州水库水体主要处于磷素限制状态。水库上游集雨区人口分布集中, 大量的生活排污与农业面源污染的输入是库区营养盐的主要来源; 合理处理上游居民生活垃圾并严格控制工业污染, 是降低库区营养盐的主要途径。此外, 人为改变高州水库的出流方式, 可以抑制浮游植物及藻类的生长, 从而减少水库富营养化的可能。     

香溪河库湾水体异养细菌及无机磷细菌分布特征

2003 年三峡水库蓄水后, 香溪河入库区段形成典型的水库型库湾, 磷污染严重, 导致水华频发。异养细菌是水体物质循环的重要参与者, 其中无机磷细菌释放结合态磷加重了水体富营养化。为了研究异养细菌和无机磷细菌对水体富营养化的影响, 在库湾设置7 个采样点, 2015 年 4 月、6 月、9 月和12 月分别采集水样, 测定样品总氮(TN)、总磷(TP)、磷酸盐(PO₄-P)及表层(水面下方0.5 m)水体叶绿素a(Chl.a)浓度, 实验室培养异养细菌及无机磷细菌。利用SPSS 17.0 对水体可培养异养细菌和无机磷细菌的时空变化进行单因素方差分析, 并用SPSS 软件分析细菌含量与总氮浓度、总磷浓度、磷酸盐浓度和叶绿素 a 浓度的相关性。结果显示: 异养细菌和无机磷细菌含量与叶绿素 a 浓度无显著相关性; 无机磷细菌与氮磷相关性均高于异养细菌, 说明香溪河库湾无机磷细菌与水体氮磷关联性大于异养细菌。     

水淹条件下三峡水库消落带常见草本植物的分解

对三峡水库消落带10种常见的一年生和多年生草本植物进行模拟淹水试验,研究水淹条件下植物分解释放氮磷规律和分解速率与植物组织内营养元素及结构性碳水化合物含量之间的关系.结果表明:不同物种分解速率不同,水花生的分解速率最大,分解速率常数k=0.0228 d-1,莠竹最小,k=0.0029 d-1,但一年生草本和多年生草本的分解速率差异不显著.一年生草本与多年生草本氮磷含量差异不显著,其中,双穗雀稗和鬼针草对水体氮磷含量影响最大;水花生氮释放能力较强,但对水体磷含量影响最小;水体中总氮、总磷含量与植物分解速率、植物体分解初始C含量、C∶N、木质素∶N呈显著负相关,与植物体K、Ca、N含量呈显著正相关.     

太湖地区湿沉降中氮磷输入量 ——以常熟生态站为例

2003年6月—2004年5月,在中国科学院常熟生态站(31°32′45″ N ,120°41′57″ E)连续定位收集降雨,分析其中颗粒态和溶解态氮磷浓度,并对期间太湖地区氮磷湿沉降动态进行研究.结果表明：湿沉降氮输入量的季节变化显著,夏、春季高,秋、冬季低;湿沉降输入氮中88.2%为溶解氮（dissolved itrogen,DN）,11.8%为颗粒氮（particle nitrogen,PN）;湿沉降输入磷中溶解磷（dissolved phosphorus,DP）和颗粒磷（particle phosphorus,PP）比例分别为53.3%和46.7%;中、小雨携带的总氮（total nitrogen,TN）、总磷（total phosphorus,TP）污染物通量大于大、暴雨;太湖地区每年湿沉降输入TN、TP分别为30.2 kg·hm^-2和1.1 kg·hm^-2,且所有降雨中DN浓度均大于水体富营养化阈值,92.5%的降雨中DP大于水体富营养化阈值.     

山美水库流域水量水质模拟的SWAT与CE-QUAL-W2联合模型

为更好地模拟分析流域非点源污染对山美水库水质的影响,联合运用流域日尺度分布式水文模型SWAT和二维垂向水动力水质模型CE-QUAL-W2,将SWAT模型的时序输出作为CE-QUAL-W2模型的输入条件,构建了山美水库流域水量水质模拟联合模型,并对流域径流、输沙和污染物以及水库的水位、水温和无机氮等变量进行了率定.结果表明: 尽管受流域部分计算结果的影响,误差会累积到对下游水库水体的计算,但模型的模拟结果与实测数据的吻合程度仍较高,说明联合模型可以较好地反映山美水库流域及库区水体的水动力和污染过程.模型的使用可以为定位流域关键污染源区及控制水库富营养化提供科学依据.     

Effect of meteorology and nutrient load on oxygen depletion in a Danish micro-tidal estuary

In a detailed analysis of oxygen saturation in a shallow Danish estuary it was possible to separate the effect of meteorological forcings (i.e. wind and solar radiation) and nutrient loads on oxygen depletion in bottom water. Regression analysis showed that oxygen saturation tied to nitrogen load rather than to phosphorus load. During summer periods of stratification the oxygen saturation could be attributed to the time elapsed after the onset of stratification and the accumulated nitrogen loading 10 month prior to measurement. Using a 10-year meteorological database and an empirical model it was calculated that a 25% reduction in nitrogen loading would reduce the number of days with severe oxygen depletion (i.e. <15% of saturation) by more than 50%.     

北京半城子水库水体营养物质表观沉降速率

表观沉降速率是流域非点源污染模型中反映水体营养物质通过不同过程,输移进入水库沉积物净效果的参数。选择位于密云水库上游的半城子水库进行水体营养物质监测,计算营养物质表观沉降速率,分析其影响因素,主要得出以下结论:半城子水库TN表观沉降速率平均为55.5mm/d,TP表观沉降速率平均为25.2mm/d,相对于世界其它地区的湖泊水库而言,TP表观沉降速率较慢。水体营养物质表观沉降速率受表层水温和水流条件共同影响。TN表观沉降速率均随表层水温的升高而递增。上游来水后,水体中P元素则经历了内源磷快速释放,之后快速沉降的变化过程。研究成果可为水污染防治和流域环境综合治理提供理论依据。     

Lacustrine sediment/groundwater nutrient dynamics

A small pond in southwestern peninsular Florida was sampled to determine the areal and depth distribution of total phosphorus, total nitrogen, and organic matter. Concentrations of these constituents decreased from the center to the edge of the pond and from the top to the bottom of the sediments. At the center of the pond total phosphorus showed a secondary concentration peak at a depth of 20 to 40 cm in the sediments indicative of the downward transfer of soluble phosphorus during times of low water.A system of monitoring wells was installed at the pond to measure groundwater input and output nutrient concentrations. There was no difference in total groundwater nitrogen concentration across the pond but the mean increase in total phosphorus concentration between input and output wells, ca. 200 g1^–1, was statistically highly significant. The results suggest that whereas nitrogen is recycled from sediments to the pond and the atmosphere, the pond-sediment system loses some phosphorus to groundwater throughflow.     

南水北调中线水源区丹江口市域景观格局变化及氮磷净化能力

丹江口库区是南水北调中线工程重要水源地,通过探究库区景观格局变化与氮磷净化能力,对未来景观规划和生态系统功能提升提供科学依据。在县域尺度上以丹江口市为研究区,运用景观格局指数和InVEST模型研究2003—2018年库区景观格局和氮磷净化能力,并利用Pearson相关分析和RDA分析法探讨二者之间的关系,分析引起氮磷净化能力变化的因素。结果表明:在斑块类型上,水域面积和林地面积不断增加,耕地和园地面积逐渐减少,建设用地面积整体上呈增长趋势;在景观水平上,景观形状指数不断减少,蔓延度指数和聚集度指数整体呈增长趋势,形状复杂程度降低,景观聚集程度提升,散布与并列指数增加了5.58,香农多样性指数变幅较小,各斑块类型趋于规则,呈均衡趋势分布。2003年、2008年、2013年和2018年氮磷净化能力呈持续增强趋势,其中TN输出总量分别为899.224、801.481、776.979、672.149 t, TP输出总量分别为77.308、69.921、68.163、60.802 t, 15年间TN、TP的净化能力分别增强了25.3%和21.4%;对氮磷净化能力重要性等级划分表明,极重要、高度重要区主要分布于库区、河流两岸和林地区域。利用Pearson相关分析和RDA分析法表明,在斑块类型上林地与氮磷的输出呈显著负相关,耕地、园地和建设用地与氮磷输出量呈正相关;在景观水平上氮磷输出量与景观形状指数呈显著正相关,和散布与并列指数表现出显著负相关,与蔓延度指数、聚集度指数呈负相关。因此,可在库区氮磷输出量较高的地区种植喜氮喜磷植物,通过调节景观格局结构,合理规划土地利用,增加林地面积,建设河岸植被缓冲带充分滞缓径流等一系列措施,充分保障库区水源水质安全。     

Potential sites of geosmin production by streptomycetes in and around reservoirs

Water from several oligotrophic reservoirs of the North West Water Authority at Longridge, Lancashire, supported only sparse growth of streptomycetes isolated from the reservoirs. Growth was enhanced by nutrient-amendment of the water and one common isolate, identified as Streptomyces albidoflavus , produced geosmin in water which was supplemented with sufficient concentrations of available carbon, nitrogen and phosphorus. The minimum concentrations required for geosmin production were higher than those recorded in natural reservoir water. Synthesis of geosmin in water also required a minimum temperature of about 15dEC. Sterilized samples of reservoir sediment, sediment extract, plant debris from banks and surrounding soil also supported geosmin production by S. albidoflavus. Both bank debris and exposed sediment developed earthy odours without inoculation. The structure of reservoir banks influenced the quantity of plant growth and accumulation of litter, and therefore also the potential for contamination of reservoir water by geosmin. The potential of these various sites of geosmin production to contaminate reservoir water is assessed.     

Nitrogen and phosphorus accumulation and cycling by Nymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae)

In 1980, the seasonal changes in nitrogen and phosphorus concentration of various plant parts of Nymphoides peltata (Gmel.) O. Kuntze, together with aspects of nitrogen and phosphorus cycling by this species were studied in an oxbow lake of the river Waal (The Netherlands). The nitrogen and phosphorus stores of the water, seston, sediment and macrophyte compartments were assessed each month.The underground Nymphoides structures had high nitrogen and phosphorus concentrations before and after the main growing season, while during summer the aboveground plant parts had high nutrient contents. Nymphoides peltata accumulated maximum amounts of nitrogen (334 mmol m⁻²) and phosphorus (56.6 mmol m⁻²) in July. The upper layers of the bottom appeared to be an enormous nutrient reservoir (94–99% of total) of which the largest part was not directly available to Nymphoides. Nutrient uptake from the sediments by N. peltata is suggested by the fact that the bottom and/or interstitial water of the sample station devoid of rooted macrophytes, contained higher concentrations of nitrogen and phosphorus than that of the Nymphoides stands. The annual flux of nutrients from Nymphoides to the detritus compartment was estimated to be ca. 1200 mmol nitrogen and 164 mmol phosphorus per m² of littoral. During breakdown of the detritus there was a relatively fast net conversion of organically bound nitrogen and phosphorus to inorganic forms, especially at higher temperatures.Nymphoides has the potential to function as an important nitrogen and phosphorus pump, which regenerates sediment nutrients.     

Impact of migratory snow geese on nitrogen and phosphorus dynamics in a freshwater reservoir

1. We examined impacts of nutrient loading, particularly of nitrogen and phosphorus, from greater snow geese (Chen caerulescens atlantica) on a reservoir in south‐eastern Pennsylvania, U.S.A. Approximately 100 000 geese use the reservoir for 2–6 weeks prior to their spring migration northward. 2. We estimated the magnitude of nutrient loading by geese during their presence and compared that to surface input and output rates. We also conducted nutrient limitation bioassay experiments to examine patterns of algal nutrient limitation upstream and downstream of the reservoir. 3. During their presence from 1 February to 27 March 2001, snow geese contributed 85–93% of the phosphorus and 33–44% of the nitrogen loaded to the reservoir. Both nutrients were exported from the reservoir slowly rather than as a quick pulse. Consequently, phosphorus concentrations in the outflow were higher than in the inflow from February to the end of July. However, nitrogen concentrations were consistently lower in the outflow than the inflow. 4. Nutrient limitation bioassays conducted in June and July indicated that primary production in the outflow was limited by nitrogen whereas the inflow was co‐limited by nitrogen and phosphorus. Further downstream from the reservoir, primary production was consistently phosphorus limited. Therefore, nitrogen limitation persisted long after the geese had left, but was relatively localised.     

Assessment of the eutrophication of Al Massira reservoir (Morocco) by means of a survey of the biogeochemical balance of phosphate

The biogeochemical balance of phosphate was studied in Al Massira reservoir (Morocco) from February 1991 to end January 1992. The study concerned P-supplies and losses by the Oum errbia river, sedimentation rate and water-sediment exchange.Supply and loss of phosphate were calculated from samples collected every 48 hours. Phosphate sedimentation rate was measured with sediment traps. The assessment of phosphate release at the water-sediment interface during either low oxic or anoxic conditions was made in situ with a benthic chamber.The results showed that phosphate input was higher than phosphate output resulting in a progressive increase of the internal phosphorus stock. The sedimentation flux ranged between 9 and 19 mg m^–2 d^–1 of P. Release of phosphate depended on the oxygen concentrations in the water.We suggest that a drastic control of phosphate input into the water must be achieved through a programme of dephosphorylation of the tributaries to avoid accumulation of calcium-bound phosphate which may become a source of upward release of bioavailable phosphate.Further investigations of this flux should be carried out to check the quantitative influence on phytoplankton community dynamics.     

厦门市海岸带水污染负荷估算及预测

综合采用灰色模型、曲线回归等预测方法,建立了基于厦门市海岸带特征的主要污染源水污染负荷估算及预测模型,并采用厦门市历年统计数据对模型加以验证.对厦门市近岸海域近10年的废水和主要污染物质排放量估算的结果表明:万元产值工业废水排放量呈逐年下降的趋势,而各污染物的排放总量却逐年缓慢增长;在点源污水排放总量预测中,约76%的氮、磷来自于生活污水;在非点源污染负荷中,农业非点源中的氮、磷负荷占较大比例,城市非点源污染负荷比例最小.2005年厦门海岸带各污染源产生的氮污染负荷大小比较结果为:生活污染源>农业非点源>工业污染源>旅游业污染源>城市非点源,磷污染负荷则为:农业非点源>生活污染源>工业污染源>旅游业污染源>城市非点源.