贵州红枫湖水体叶绿素a的分布与磷循环

于2009年8月(夏季)和2010年1月(冬季)在贵州红枫湖采集了分层湖水和分层沉积物样品,分析了湖水样品的总N(TN)、总P(TP)及叶绿素a(Chl-a)含量,结果表明,湖水TN含量在2个季节无明显变化,平均含量为1.58±0.73 mg·L-1,湖水TP含量夏季(0.091±0.070 mg·L-1)高于冬季(0.026±0.055 mg·L-1).夏季湖水在8 m处有季节性分层,下层湖水TN、TP含量高于上层;夏季湖水Chl-a主要集中在上层,上层平均含量为33.2±13.0 mg·m-3,冬季湖水Chl-a平均含量为11.1±3.7 mg·m-3,分析发现,湖水上层(8 m)Chl-a与TP有明显的线性相关关系(r=0.965,P＜0.01),表明红枫湖富营养化主要受P元素限制.沉积物孔隙水中的溶解态P(DP)浓度和湖水的磷酸盐(PO3-4-P)浓度比上覆水体高,具有向上扩散的趋势,利用费克第一定律计算了沉积物向上覆水体的释P速率,发现夏季沉积物向上覆水体释P速率高于冬季,可能主要是由于夏季湖水底层的还原环境下沉积物表层的早期成岩作用生成磷酸盐进入孔隙水而促进了沉积物向上覆水体释放P.根据通量释放结果估算了全湖沉积物向水体的释P通量,约为每年5.0±5.6 t.红枫湖富营养化受P控制,沉积物向水体有很大的释放P的潜力,是湖水P的重要内源,严格控制流域的外源输入才能彻底治理该湖的富营养化.     

岱海表层沉积物中内源磷的释放

以北方半干旱地区典型内陆封闭湖泊岱海为研究对象,开展了上覆水质及多种环境因子(温度,pH,溶解氧,扰动,光照)对湖泊沉积物内源磷释放的影响研究。结果表明:(1)温度升高有利于内源磷的释放,湖泊水体在温度较高的夏季更易呈现富营养化状态;(2)碱性条件有利于磷的释放,岱海水体属微碱性环境(pH8.8),若水体pH进一步升高,将会造成沉积物内源磷的大量释放;(3)厌氧条件(ρDO0.8mg/L)有利于磷的释放,岱海湖心区水深较深,易形成厌氧环境,因此湖心区内源磷释放强度较浅水区大;(4)强烈扰动有利于磷的释放,这会对浅水区的底质产生较大影响;(5)照度通过底栖藻类的生物作用,间接地限制了沉积物释磷对上覆水中磷浓度的影响。     

完全水淹环境中光照和溶氧对喜旱莲子草表型可塑性的影响

光照和溶氧是水环境和陆地环境间差异显著的两个环境因子,对水淹植物的生长和存活具有重要的意义。以三峡库区常见外来入侵植物喜旱莲子草(Alternanthera philoxeroides)为研究对象,考察了水体中的光照(L)和溶氧(DO)对完全水淹环境中喜旱莲子草的形态特征和生物量分配等表型可塑性的影响。实验设置水淹和非水淹对照两组处理,对水淹组的光照和溶氧两个环境因子再分别设置有(+)、无(-)以及高(+)、低(-)两种水平,共计4个处理。实验结果表明:(1)水淹可促进喜旱莲子草主茎和叶片发生可塑性反应,引发伸长生长。水淹后,其细长的主茎以及长而薄的直立叶更有利于植株早日出露水面。(2)完全水淹条件下,喜旱莲子草主茎和叶片的表型可塑性受光照和溶氧的复合影响,其中主茎的伸长生长主要受溶氧的影响,而叶片的形态变化则主要受光照影响。高溶氧处理下喜旱莲子草的主茎伸长生长显著(P0.05)。在相同光照条件下,高溶氧处理下喜旱莲子草的主茎长、节间数、节间长以及主茎长/主茎直径均明显高于低溶氧处理。不论有光还是无光,高溶氧处理下喜旱莲子草主茎长以及节间数的平均增长率均处于最高水平,分别为61.8%、34.2%。喜旱莲子草叶片的形态变化在有光处理下表现得尤为显著,其平均叶片长宽比、比叶面积以及叶倾角分别较水淹前增加了39.65%、28.3%、45.9°。(3)光照和溶氧对于喜旱莲子草不定根和分枝的发生及发展存在影响差异。有光条件下可促进植株抽枝,而高溶氧处理时更有利于植株生根。这些形态变化有助于喜旱莲子草扩大株型占据有利生境,进一步提高植株的水下存活能力。     

富营养化山仔水库沉积物微囊藻复苏的受控因子

山仔水库作为福建省福州市重要的饮用水水源地之一,从2000年起每年都周期性爆发蓝藻门微囊藻属(Microcystis)水华现象,特别是在温暖的季节。对于这个富营养化水库,是否在沉积物中存在蓝藻门微囊藻的"种源"？假设山仔水库底泥中存在蓝藻门微囊藻休眠体,一定的环境条件能够促进蓝藻门微囊藻的复苏。研究于2009年12月采集水库大坝断面5根柱状沉积物,采用正交试验的方法,模拟了温度、光照、pH值、营养盐、物理扰动和浮游动物(膨大肾形虫)等环境因子对山仔水库沉积物中蓝藻门微囊藻的复苏响应。结果表明,底泥中存在着一定数量的底栖动物和硅藻、蓝藻和绿藻等微藻,从实验结束后沉积物中微囊藻数量的减少和上覆水体中微囊藻数量的增加,可以判断在适宜的环境条件下,蓝藻门微囊藻能够复苏并上浮到上覆水体中。正交实验显著性分析表明,温度是沉积物蓝藻门微囊藻复苏的重要影响因子,光照次之,上覆水体的pH值、营养盐、物理扰动和浮游动物干扰对沉积物蓝藻门微囊藻的复苏影响作用不显著,升温有利于沉积物中微囊藻的复苏。     

阿哈水库沉积物-水界面重金属扩散通量

为了解阿哈水库水体中重金属的污染现状,选取了4个典型点位进行夏、冬两季采样分析,研究了上覆水体及沉积物孔隙水中Co、Ni、Cu、Zn、As、Cr及Pb 7种重金属的时空分布规律及其界面扩散通量。结果表明:阿哈水库上覆水体中溶解性重金属的均值含量符合我国《地表水环境质量标准》(GB 3838—2002)Ⅰ类标准与《生活饮用水卫生标准》(GB 5749—2006),未受到重金属污染。夏季分层期,底层水缺氧导致水体As、Co、Cr含量增高,而冬季混合期重金属的垂向变化较小。沉积物孔隙水中重金属浓度均值高于上覆水,且Co与Ni、As呈显著正相关,其在水库中的迁移转化过程受铁锰循环的共同影响; Cu、Zn与Pb存在正相关关系,具有相似的污染来源。分析沉积物-水界面重金属扩散通量显示,Zn保持负扩散,表明沉积物对Zn具有很好的净化吸附效果;而Co、Ni、As、Pb保持正扩散,特别是夏季As的扩散通量达2.07μg·cm~(-2)·a~(-1),对上覆水体可能产生较大的释放风险。研究证实,近十年来阿哈水库水体重金属的污染控制取得了显著的效果。     

衰亡期沉水植物对水和沉积物磷迁移的影响

通过室内模拟的方式,分别研究了秋季黑藻、苦草和春季菹草的衰亡过程,分析了沉水植物在衰亡期间水、沉积物中磷与环境因子[pH、氧化还原电位(Eh)和溶解氧(DO)]的相互作用.结果表明:沉水植物黑藻和菹草在衰亡期间能显著提高水中总磷(TP)、溶解性总磷(DTP)、颗粒磷(PP)、溶解性活性磷(SRP)和溶解性有机磷(DOP)的含量;苦草在衰亡期对水体各形态磷含量影响不显著,且各形态磷含量的变化相对较小(TP,0.04-0.06 mg/L);环境因子的变化对水中磷含量影响显著,黑藻和菹草水体中TP的含量和环境因子pH、DO和Eh均呈负相关,而苦草组水中各形态磷的含量受环境因子影响不显著.实验期间不同植物组沉积物中总磷(TP)、NaOH提取磷(NaOH-P)、HCl提取磷(HCl-P)、无机磷(IP)和有机磷(OP)的含量均呈上升趋势.沉积物IP的含量主要受NaOH-P的影响,OP对TP的影响要大于IP,沉积物OP与OM(有机质)的含量存在显著正相关.     

滇池试验围隔内不同形态铁浓度的变化与物化因子的关系

在蓝藻水华形成以后,通过围隔实验,从2003年6月份到10月份定期采样测定水体中的pH、溶解氧(DO)、水温、总铁、亚铁、过滤性铁(<0.45μm)和可溶性磷的浓度,研究物化因子对不同形态铁浓度变化的影响。实验结果表明,蓝藻水华优势种微囊藻在pH 7—9和水温17.5—20.5℃的条件下,生长旺盛,消耗了大量的亚铁,使亚铁浓度大幅度下降;溶解氧和磷酸盐对亚铁浓度没有显著影响;在水华蓝藻严重发生的条件下,水体中的总铁和过滤性铁浓度没有显著意义的变化,而亚铁浓度的变化与水华蓝藻的种群密度成显著负相关(r=-0.8391,P<0.05)。     

光照和营养盐磷对微型及微微型浮游植物生长的影响

2004年9月,在长江口及邻近水域通过在培养水体中添加不同量的磷酸盐和改变光照强度进行现场受控培养实验,对光照和营养盐磷耦合培养作用下浮游植物生长及对磷营养盐的吸收变化进行了研究,结果表明：高光照条件下（100﹪自然光照）,磷酸盐浓度在高磷水平（0.60μmol/L）培养水体中下降速率明显比中磷（0.41μmol/L）、低磷水平（0.25μmol/L）快,浮游植物生长存在着显著的磷限制性,微型浮游植物（nanophytoplankton,简称Nano,2～20μm）在高磷水平下的生长明显得到促进,聚球藻（Synechococcus sp.,简称Syn,＜2μm）密度在培养初期有小幅度增加,而微微型真核浮游植物（picoeukaryote,简称Euk,＜2μm）在低磷水平下生长较快;在低光照条件下（50﹪自然光照）,磷酸盐浓度在高磷水平培养水体中的下降是受到抑制的,Nano和Syn也都更宜在中磷水平培养水体中生长,Euk在高磷水平下的生长也是受到抑制的,且在中磷水平培养水体中,三类浮游植物的生长周期都得到延长;无光照暗环境培养条件下磷酸盐浓度在不同磷水平下始终保持着增加趋势,三类浮游植物也都无法生长,磷酸盐浓度随培养时间呈线性增加趋势,浮游植物细胞密度则呈指数下降趋势,且磷酸盐的添加对其本身的释放速率和浮游植物衰减速率都没有影响.     

沉积物生源要素对水体生态环境变化的指示意义

受人类活动影响,输入到湖泊、河口中的营养盐剧增,导致水体富营养化、食物链结构改变、底质季节性缺氧等生态环境变化。这些环境变化会在沉积物中留下记录,沉积物中生源要素及其稳定同位素的变化是指示水域古生产力、营养盐水平的有效指标。总结归纳了沉积物中生源要素(碳、氮、磷、硅)指标对水体环境中初级生产力、物质来源、营养盐水平3方面变化的指示作用。沉积物中TOC、TN、δ13C、CaCO3和BSi可以反映水体沉降有机质含量和浮游植物的生长状况,是指示水域初级生产力水平的有效指标。根据不同类型植物来源的有机质中δ13C、δ15N和C/N的差异,可以追踪沉积物中有机质的来源。有效地区分有机质来源对于研究人类活动对水体环境的影响及水体富营养化具有重要的价值。沉积物中TN、δ15 N、TP和非磷灰石磷(NAIP)含量的升高直接反映了陆源输入氮、磷的增加。BSi在指示浮游植物生长状况的同时,还反映了水体溶解硅浓度水平和富营养化状况。水体中的生源物质在沉降和埋藏的过程中,会受到早期成岩作用、水动力搬运等众多因素的作用,使沉积物记录的环境变化信息发生改变,从而干扰其对水体环境演变的重建作用。因此综合分析各生源要素指标反映的环境变化信息及其可能的干扰因素,方能正确地反映水域的环境变化过程。     

富营养化湖泊沉积物磷原位控制技术简

正湖泊沉积物是指湖泊中沉积的物质,湖泊中大量营养盐富集在沉积物中。水体中各形态的磷通过污水排入、地表径流及水生生物残骸等多种途径输入至湖泊,在温度、上覆水pH、溶解氧及氧化还原电位等环境因素的影响下,经过一系列变化,其中水体中的部分磷在沉积物吸附、化学絮凝、共沉淀等作用下蓄存于湖泊沉积物中,     

A dynamic phosphate budget model for a eutrophic lake

The relations between the external nutrient loading of lakes, recycling through sediments and the resulting productivity are complicated by feed-back mechanisms, seasonal variations and trends. Simulation is a useful tool for the identification of controlling factors and the assessment of the effects of management measures, supplementary to experimental research. The model variables in our dynamic phosphate budget model include inorganic and organic particulate phosphate and dissolved o-phosphate, in both sediments and overlying water. Sediments may be aerobic or anaerobic, depending on topography, temperature and composition. The major processes described are primary production, mineralisation, sedimentation, adsorption and diffusion. Several model parameters have been estimated directly for Lake Brielle (Netherlands). The sediment dilution rate, the extent of anaerobic conditions and the number and character of adsorption sites are important controlling factors.     

Factors influencing phosphate exchange across the sediment-water interface of eutrophic reservoirs

The results of a survey of the sediment chemistry of 7 East Anglian reservoirs are presented as part of a regional study on the assessment and control of eutrophication. The influence of water quality (dissolved oxygen, pH, temperature) on phosphate (PO₄) adsorption by sediment from hypertrophic Ardleigh Reservoir is also examined. Extractable phosphate-P (extr.-P) varied between 92 and 383 mg kg^–1 dry matter. Extractable P varied between 5.3 and 16.6% of the total phosphate-P (Tot. P) content and increased with the concentration of dissolved reactive phosphate-P (DRP) in the overlying water column. Organically complexed iron (organic Fe) was the determinand which correlated most closely with phosphate adsorption capacity, PAC (r = 0.8). Organic Fe was also related inversely to Extr. P. The rate and extent of PO₄ adsorption by Ardleigh Reservoir sediment increased with the initial concentration of DRP and adsorption equilibria were reached after 24 h. The equilibrium DRP concentration, [DRP], was 0.7 mg P 1^–1 under aerobic conditions indicative of a high potential for PO₄ exchange. The rate and extent of PO₄ adsorption was greater at 7 °C than at 22 °C PO₄ adsorption increased markedly with dissolved oxygen status. Ardleigh sediment exhibited a marked buffering capacity to a change in pH; however, PO₄ adsorption was greatest at an equilibrium pH of 5.6 and decreased progressively either side of this pH value.Options for the artificial control of sediment PO₄ release are discussed in relation to the seasonal variation in sediment PO₄ exchange observed for Ardleigh Reservoir.     

Spatial variation of phosphorus fractions in bottom sediments and the potential contributions to eutrophication in shallow lakes

Spatial variation of phosphorus fractions in bottom sediment, pore water and overlying water in three shallow eutrophic lakes, Nishiura, Kitaura and Sotonasakaura, Japan, and the contributions of the fractional P to mobilization of phosphorus from sediment were examined in this study. The vertical distributions of dissolved inorganic phosphorus (DIP) concentrations in overlying and pore water differed with lake and sampling site. In particular, DIP was high in pore water in the surface layer of the sediment for the middle to downlake areas of Lake Kitaura. DIP release flux calculated from a gradient of the concentrations at the sediment–water interface was high compared with other sites. The distribution of fractional P content in sediments was highly variable. The citrate–dithionite–bicarbonate–non-reactive phosphorus (CDB–NRP) fraction, in particular, differed greatly among the three lakes. According to correlation in the ratios between CDB–NRP and loss on ignition, sediments of these lakes were classified in three clusters. The CDB–NRP fraction was suggested to play a role in DIP release from sediment. The possibility of nitrate concentration playing a role in the control of DIP release was considered.     

溶氧振荡对聚β羟基丁酸混合培养过程的调控作用

研究生物可降解塑料PHB(Poly β-hydroxy butyrate)生产的低成本和高产率发酵。采用廉价碳源——废食品糕点作为原料,其中同时具有葡萄糖和乳酸。培养是在同一5L发酵罐中先后接入2种细菌,先由乳酸杆菌Lactobacillus delbrueckii消耗葡萄糖产生乳酸,再由真养产碱菌Ralstonia eutrophus消耗乳酸产生PHB。本文应用混沌控制理论设计溶氧振荡来协调混生菌矛盾的生理需求,同时改变振荡节律激励细胞的代谢能。考虑真养产碱菌在乳酸里的代谢,有异养和真养两种途径,其中两种重要代谢通量,生物氧化能ATP和还原能NADPH,能够反映混生菌细胞的生理状态,二者都与供氧密切有关。实验通过取样进行细胞破碎后,由荧光分析仪监测不同发酵阶段的ATP和NADPH,发现2种代谢能随着溶氧控制的不同节律变化而起伏,溶氧节律振荡能够使混合培养的PHB的浓度比常规供氧方法提高1倍。     

Effect of dissolved oxygen concentration onnar promoter activity in batch and semi-continuous cultivations

The level of the dissolved oxygen concentration could significantly affect thenar promoter activity in the induction of the gene expression under the anaerobic condition. In batch culture, the β-galactosidase activity was about 12000 units/min/g cell under the anaerobic condition. The optimum DO concentration for the induction of the gene expression was 0% in both batch and continuous cultivations. In semi-continuous culture, the maximum enzyme activity was about 11000 units/min/g cell at 0% of the DO concentration. These results indicated that the absolutely anaerobic culture condition was required for the maximum gene expression.     

Degrading seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) ecosystems: a source of dissolved matter in the Mediterranean

Diurnal variation of dissolved oxygen (DO), organic and inorganic carbon (DOC, DIC), nitrogen (DON, DIN), and phosphorus (DOP, DIP) flux across the sediment–water interface was assessed in fish farm impacted and pristine seagrass (Posidonia oceanica) meadows in the Aegean Sea (Greece). DIC consumption decreased by 52% and DO production decreased by 60% in the light, suggesting reduced photosynthetic performance of the plant community under the fish cages probably due to organic matter loading. In light there was 4 and 15 times higher release of dissolved inorganic and organic matter, respectively, compared to dark incubations under the cages, indicating that fish farming impact is more intense during daytime. DO was taken up, while DIC was released in the dark in both stations, representing a direct measure of mineralization. Dissolved inorganic matter flux (as the sum of DIN and DIP fluxes) was positively related to DIC flux, rendering mineralization as the main driver of nutrient flux under the cages. On average, the impacted meadow released DIN and DIP both in light and dark, while efflux of dissolved organic matter (as the sum of DOC, DON, and DOP fluxes) increased by 132% in the light and by 21% in the dark, implying that the degrading seagrass meadow is a source of dissolved matter to the surrounding water. Shoot density and leaf production were negatively correlated with both diel DIN and DIP fluxes, showing that meadow regression is accompanied by DIN and DIP release from the sediment. Hence, nutrient efflux can adequately illustrate meadow deterioration and, therefore, can be used as indicator of P. oceanica community health.     

Bioturbation potential of chironomid larvae for the sediment–water phosphorus exchange in simulated pond systems of varied nutrient enrichment

Chironomid larvae (2.0 individuals/cm²) were introduced in sediment–water microcosms of 3.0 l capacity to assess the impact of bioturbation on phosphorus flux across sediment–water interface, under different nutrient-enriched conditions. Recruitment of chironomid resulted in 21% and 19% increase in aquatic orthophosphate and nitrate quanta, respectively, with concomitant decrease in nutrient concentration in the sediment compared to macrofauna-free controls under mesotrophic condition. It implied that cost of fertilizer for biological production could be curtailed by at least 19–21% by recovering nutrients stored in the sediment pool. Bioturbation-induced orthophosphate flux under chironomid impacted mesotrophic treatment was 2.3- and 1.8-fold greater than that under bioturbated eutrophic treatment, suggesting that the macrofaunal impact was reduced in the presence of higher nutrient load perhaps due to physicochemical stressors under eutrophic condition. Nevertheless, chironomid larvae can further accelerate nutrient enrichment in the eutrophic system that may invite a “snow ball effect” towards a hypereutrophic one. The counts of both heterotrophic and phosphate solubilizing bacteria show strong positive correlation with orthophosphate concentration in water and the correlation also exists between organic carbon concentration in sediment and phosphate in overlying water. This implied that the accelerated phosphate flux was the result of coordinated eco-engineering activities of chironomid larvae and microbe-mediated mineralization of organic matter.     

太湖春季沉积物间隙水中磷的分布特征及界面释放的影响

通过对太湖春季不同湖区水体和沉积物间隙水中磷的分布特征研究,探讨了间隙水中磷的释放对上覆水环境的影响。结果表明,颗粒态磷(PP)和溶解态有机磷(DOP)是太湖水体中主要的磷形态,占总磷的58%～95%。不同湖区沉积物间隙水磷的剖面变化可能与生态特征及水动力引起的沉积物-水界面的扰动强度密切相关。湖心和西部沿岸沉积物扰动强烈,致使间隙水中磷含量向上逐渐降底,而梅梁湾和贡湖间隙水磷的垂向变化不大。东太湖和竺山湖沉积物界面间隙水中磷含量偏高,可能是由于表层沉积物的有氧环境使Fe2+被氧化固定下来,并促进了总磷(TP)和溶解态活性磷(DRP)的扩散释放。总体而言,间隙水中各形态磷具有向上覆水体释放的趋势,其中DRP的扩散潜力最大,竺山湖沉积物-水界面DRP扩散通量高达11.42mg.m-2.d-1,表明春季浮游植物的复苏生长对DRP的迫切需求。     

溶氧对Candida glycerinogenes产甘油发酵过程的影响

研究了溶氧浓度对产甘油假丝酵母分批发酵生产甘油过程的影响。实验结果表明：当溶氧浓度控制在30%时,C. glycerinogenes的甘油产量、得率和产率达到最高,分别为120.7 g/L、0.575 g/g和1.69 g/(L•h),而糖酵解代谢副产物形成最少。当溶氧浓度为10%时,发酵过程呈现出“巴斯德效应”的特征,生成的酵解代谢副产物维持在较高水平。在快速生长阶段,随着溶氧从10%增加到60%,细胞呼吸类型表现为从厌氧呼吸向好氧呼吸转变,酵解代谢副产物依次减少。在生长稳定期,控制的溶氧浓度越高,酵解代谢副产物乙醇、乙酸等的生成减少。分别选用Logistic方程、Luedeking-Piret方程和Luedeking-Piret-like方程,能较好地模拟细胞生长、甘油合成和葡萄糖消耗的动力学过程。     

Solute dynamics in a North Brazilian mangrove: the influence of sediment permeability and freshwater input

Although water in mangrove sediments influences nutrient cycling in both, mangrove forest and estuary, little information exists on seasonal and vertical distribution of dissolved organic and inorganic compounds in the sediment column. We studied the influence of sediment texture and chemistry, permeability (K), tides, and rainfall on dissolved organic carbon (DOC) and nitrogen (DON), dissolved inorganic phosphate (DIP) and salinity in creek and sediment waters of a mangrove in Pará, Brazil. Water samples were taken from boreholes and piezometers in the mangrove forest and from an adjacent tidal creek at neap and spring tides, during the dry and rainy season. Forest sediment was analysed for carbon (C), nitrogen (N), salinity and permeability. Clay, C and N decreased with depth. Sediment permeability (K) was lowest (<0.1 m day⁻¹) in the upper, clay-rich and crab-burrow-free mud layer. In the deeper, fine sand strata, K ranged from 0.7 to 1.8 m day⁻¹. Tidal range in the creek was 3.5 and 5.5 m for neap and spring tides, respectively. Salinity, DOC, DON and DIP in creek water were inversely related to tidal height. Piezometer data revealed significant water level changes in deeper, sandy sediment layer, which followed, time-lagged, the tidal fluctuations. In contrast, tide did not affect the water level in the upper sediment due to low permeability. Compared with creek water, sediment water was enriched in DOC, DON and DIP because of organic matter input and mineralization. In deeper layers, solute concentration was most likely affected by sorption processes (DOC and DIP) and reduction reactions (DIP). During the rainy season, DOC and DON in creek and sediment water were higher than in the dry season. DIP appeared invariant to seasonal changes. In the rainy season, salt flushing from surface sediments resulted in higher salinities at intermediate sediment depths, while in the deeper layers salinity was lower due to exchange with water from the tidal creek.