南四湖现代沉积物中营养元素分布特征

对南四湖不同湖区20个表层沉积物和独山湖湖区沉积岩芯中营养元素进行了分析结果表明表层沉积物中南阳湖总磷最高,独山湖次之;独山湖总有机碳和总氮含量最高,南阳湖次之;而昭阳湖总有机碳、总氮和总磷含量较低.沉积岩芯中137Cs数据表明南四湖独山湖区柱状沉积物上部(0-18 cm)沉积速率为3.5mm/a;总有机碳、总氮和总磷含量主要集中在沉积岩芯0-8 cm内,并呈现一致的垂向分布规律,具有明显的三阶段分布特征,反映了流域社会经济的发展导致营养元素的释放量增加,造成了湖泊现代沉积物中营养元素的积累.碳氮比值处于7.6-11.4之间,有机质的选择性分解不明显,指示沉积物中有机质主要来自无纤维束的陆源植物.监测数据表明济宁市的城市生活污水、工农业废水排放进入南阳湖是南四湖有机质和TP富集的主要来源.     

巢湖表层沉积物中生物易降解物质成分特征与分布规律

富营养化湖泊的藻类残体大量沉降到湖底,其中易降解成分的降解和转化快速消耗底层水体中的溶解氧,极易造成水土界面缺氧,影响湖泊生态系统的健康.于2014年对巢湖12个样点的表层沉积物进行周年跟踪研究,分析样品中有机质来源、总有机碳(TOC)、蛋白质、总糖、总脂以及生物聚合物碳(BPC)等成分含量,揭示易降解有机质的成分特征及在巢湖的分布规律.研究表明:巢湖表层沉积物TOC含量较高,全湖样点平均含量达到1.24%.BPC含量占TOC含量的30.99%~60.48%,有机质中易降解成分含量较高,并且在冬季和夏季时在巢湖西北部湖区有明显累积;有机质及其中的生物易降解部分均主要集中在粒径4~8μm的表层沉积物上,在应用工程技术手段处理、降解表层沉积物中的过量有机质时,更应该关注粒径为4~8μm的沉积物颗粒.     

不同水动力扰动下太湖沉积物的悬浮特征

利用2002年7月及2003年4月分别在太湖乌龟山和梅梁湾的水动力观测资料,计算了波浪和湖流产生的湖底切应力,分析了二者对太湖沉积物悬浮的不同贡献.结果发现,在小扰动情况下,流切应力大于波切应力,但不能引起沉积物的悬浮;在强扰动情况下,底流对沉积物悬浮的影响可以忽略,且扰动越强,其作用越小,而波浪的影响却愈加突出;在中等扰动下,二者的相互作用产生沉积物的悬浮,但波浪的作用较为显著.该结论能为计算太湖水体悬浮物浓度和动态内源释放提供重要的参考依据.     

巢湖湖滨带藻类水华期异味物质的空间分布规律及其影响因素

为探究湖滨带藻类水华期水体异味物质的空间分布规律,2019年6—10月对巢湖湖滨带水体理化参数和异味物质进行月度调查,分析湖滨带水体异味物质的空间分布特征,并探讨影响其空间分布差异的主要因素。结果表明：巢湖湖滨带藻类水华期水体异味物质浓度在空间上总体表现为西北部湖区最高,南部湖区次之,东北部湖区和北部湖区最低的分布特征,藻类生物量高低及其分解是水体异味物质产生空间分布差异的主要原因。风向和风速间接影响了湖滨带水体异味物质的空间分布,其中北部湖区受风速和风向的影响最为明显,其次是南部湖区和东北部湖区,西北部湖区影响最小。此外,湖滨带植被通过影响该区域藻类水华堆积及消散过程加剧了水体中异味物质的富集。     

不同生态修复措施下太湖西五里湖沉积物氮磷形态的时空分布

以太湖西五里湖为研究对象,研究了生态修复工程实施两年后,疏浚区、疏浚并水生植被重建示范区、退渔还湖区及对照区沉积物中氮、磷形态的季节变化及垂直分布特征,同时分析了各区上覆水的氮磷含量.结果表明:生态修复措施的实施对沉积物中氮磷形态分布及上覆水的氮磷含量影响显著.示范区和退渔还湖区水体中氮磷含量较低;沉积物中不同磷形态的垂直分布变化较复杂;疏浚基础上进行的水生植被重建对Lab-P、Al-P、Fe-P的吸收作用显著,对Ca-P、Org-P的影响较小;退渔还湖区沉积物磷形态以Ca-P、Org-P为主,Fe-P所占比例较低,与疏浚区不同.生态修复措施对沉积物中TN的影响较小;示范区NH 4 -N含量在秋季突增,可能与植物残体形成的有机质的分解有关.疏浚区水体中氮磷含量与对照区差别不大,沉积物中TN的平均含量还略高于对照区,因此单一的疏浚措施对水环境改善的长期作用需要进一步研究.而示范区水体及沉积物中的TN、TP含量均比较低,水生植被恢复较好,可见在减少外来污染的前提下,对湖区底泥进行疏浚并开展水生植被恢复工程应该是控制湖泊富营养化的有效途径.     

长江中下游湖泊沉积物中磷的形态及藻类可利用量

调研了长江中下游地区25个浅水湖泊的35个样点表层沉积物中磷的地球化学形态特征,以及太湖沉积物中藻类可利用磷(AAP)的空间分布,垂向分布特征及其蓄积量,探讨了浅水湖泊表层沉积物中磷的赋存量,地球化学形态及其与水草,湖水磷浓度,叶绿素(Chl-a)浓度之间的关系.结果表明,长江中下游地区浅水湖泊的表层沉积物中可交换态磷(Ex-P)含量与水体总磷(TP),溶解性总磷(DTP)及溶解性反应活性磷(SRP)浓度关系密切,有水草湖区的沉积物中生物易利用磷(Bio-P)含量显著低于无水草湖区及藻型湖区.太湖梅梁湾沉积物泥芯中,表层3 cm沉积物中Ex-P含量显著增高,而夏季还原条件下容易转变为溶解态磷的铁磷(Fe-P)含量峰值则出现在4～10cm深度.太湖表层沉积物的Bio-P含量与夏季叶绿素浓度密切相关,说明表层沉积物的Bio-P及AAP可以作为沉积物内源释放风险的指示参数.太湖表层1 cm底泥中所含有的AAP量估计多达268.6吨,风浪扰动能将大量的AAP带入水体,对太湖蓝藻水华暴发起着不可忽视的作用.     

贵州红枫湖越冬藻类的空间分布与实验室复苏实验

本文选取贵州省红枫湖这一典型的亚深水型湖泊作为研究对象,在8个代表性湖区开展了为期一年的表层水体藻类浮游植物分布的月定量监测,并在4个采样点采集新鲜沉积物进行了越冬藻类赋存与复苏模拟实验研究.研究表明,红枫湖表层水体藻类种群密度蓝藻绿藻>硅藻>甲藻,蓝藻为优势门类,水体藻类种群密度秋季初期最高,其次是春季初期和夏季,具有明显的季节性演化特征.水体中越冬藻类以蓝藻为主,其次是硅藻和绿藻,水深对水体中藻类的种群密度及组成没有显著影响.沉积物中越冬藻类以硅藻为主,基本不含蓝藻.模拟实验表明,水体中的光照条件对藻类的复苏和生长有重要影响,温度和沉积物中藻类的种群密度与组成同样影响藻类的复苏.     

红枫湖、百花湖沉积物全氮、可交换态氮和固定铵的赋存特征

氮是引起湖泊水体富营养化的关键营养元素之一。本次工作从贵州两个重要水库（红枫湖和百花湖）采集了未受扰动的沉积物样品性,分析了分层沉积物样品中的总氮,无机交换性氮和固定铵的含量及垂直剖面分布,研究表明,红枫湖和百花湖沉积物中具有较高的全氮含量,平均含量约为沉积物干重的0.36%～0.40%,其垂直分布在埋藏过程中受到成岩作用改造,沉积物交换性氮在沉积物中的赋存受到全氮含量和埋藏环境的双重控制,红枫湖和百花湖沉积物具有较强的吸持固定铵的能力,沉积物固定铵的绝对含量的平均值分别为434.05mg/kg和416.94mg/kg,分别占全氮的13.53%和12.53%。     

哈纳斯湖的水下地貌与表层沉积物的若干特征

测量表明,哈纳斯湖最大水深达188.5m,平均水深达120.1m,优质淡水容量达53.78×10~8m~3,均在我国湖泊中居突出地位。横断面为罕见的典型箱形,断陷作用仍在强烈进行之中。湖底表层沉积物粒度参数之分布主要受纵向搬运作用控制,局部受横向搬运作用影响。沉积物的矿物学特征与元素分布特征明显受沉积环境控制。沉积物中营养元素含量总体偏低。~(210)Pb法测得平均沉积速率为0.52mm/a,难以补偿断陷作用,湖盆将继续加深。     

太湖水体和沉积物细菌群落分布格局及其驱动因素

水体和沉积物是湖泊生态系统中迥异但又紧密相连的两类生境,栖息在这两类生境中的细菌在维持生态系统平衡和驱动元素循环中起着关键性作用。为了探究湖泊水体和沉积物细菌群落的分布格局,本文对太湖四个湖区水体和沉积物中细菌群落进行调查,基于高通量测序技术和统计分析手段,分析这两类生境中的细菌群落组成和多样性水平、分布特征及其驱动因素。结果表明:放线菌门(Actinobacteria)、变形菌门(Proteobacteria)和蓝细菌门(Cyanobacteria)是水体细菌群落中最主要的细菌门,而沉积物中Proteobacteria占据优势地位。在两类生境中,太湖西部区域细菌群落丰富度和独特性(LCBD)相对较高,各区域群落结构表现出显著性差异。对水体而言,电导率、pH值、PC1(重金属组成)和沉积物孔隙度是驱动细菌丰富度的重要因子,PC1、水温及pH值是影响细菌群落LCBD的重要因子,而细菌网络复杂性随pH值的增加而增加,且在高pH环境中占主导地位;对沉积物而言,其丰富度和LCBD的重要影响因子均是沉积物中总磷和锂,细菌网络复杂性随金属元素施加的环境压力增大而降低,但随总磷、磷酸盐和铵态氮浓度的...     

太湖底泥悬浮中营养盐释放的波浪水槽试验

波浪水槽中研究了小波掀沙(波高8.77cm,波周期0.8s)和大波掀沙(波高12.31cm和13.29cm,波周期1.0s)对太湖沉积物悬浮及N、P营养盐释放的作用规律.结果显示:小波掀沙时,底泥并未发生大量悬浮,SS浓度最高时仅13.6mg/L;大波掀沙时,底泥大规模悬浮,SS浓度最高达达245.2mg/L水体悬浮物、营养盐浓度变化滞后波高变化1h以上.当波高改变1h后,水体悬浮物、N、P营养盐浓度才改变到相应的平衡浓度.除总磷浓度显著提高外,小波掀沙对水体N、P浓度的影响很小,大波掀沙则显著提高了水体总氮、总溶解氮、总磷、总溶解磷、氨氮(NH4 -N)、溶解性活性磷(SRP),其中NH4 -N、SRP最大增幅达30％和20％.小波和大波掀沙过程中,水体溶解氧浓度均持续增加,掀沙2h后增高2mg/L,溶解性有机碳持续下降,2h后下降33％-51％.试验结果表明,掀沙过程中水体充氧及颗粒物的絮凝、吸附作用可能是限制NH4 -N、SRP浓度增高的重要因素之一.     

基于FVCOM的太湖梅梁湾夏季水温、溶解氧模拟及其影响机制初探

水体中的溶解氧是表征水生生态系统健康与否的重要参数之一.本研究基于太湖2008年8月16 20日的风速、风向、短波辐射等气象场资料以及实测的相关水质参量,利用FVCOM(即非结构化网格有限体积近海海洋模型)模式对太湖梅梁湾三维水温以及水体中溶解氧进行模拟,模拟结果与实测值基本吻合,水温的验证回归方程为y=1.02x,R²为0.690;溶解氧的R²为0.760.同时对溶解氧浓度的时空分布,梅梁湾溶解氧的"源"和"汇"及其贡献进行了分析.结果表明:太阳辐射、风速是影响水温日成层现象的重要因子;受水温和光照的影响,夏季梅梁湾的溶解氧存在垂直差异,呈现出"双峰双谷"的日变化特征;浮游植物光合作用制氧是水中溶解氧的最重要来源,水下光衰减直接控制着初级生产力的垂直分布;浮游植物呼吸及死亡是溶解氧的最大消耗者,余下依次为底泥耗氧、碳化需氧、细菌呼吸耗氧和硝化作用耗氧.     

Environmetric and GIS techniques for hydrochemical characterization of the Dal lake,Kashmir Himalaya,India

This research explains the background processes responsible for the spatial distribution of hydrochemical properties of the picturesque eutrophic Himalayan Lake, Dal, located in Kashmir valley, India. Univariate and multivariate statistical analyses were used to understand the spatiotemporal variability of 18 hydrochemical parameters comprising of 12,960 observations collected from 30 sampling sites well distributed within the lake at a grid spacing of 1 km² from March 2014 to February 2016. Hierarchical cluster analysis (HCA) grouped all the sampled data into three clusters based on the hydrochemical similarities, Discriminant analysis also revealed the same clusters and patterns in the data, validating the results of HCA. Wilk’s λ quotient distribution revealed the contribution of ions, nutrients, secchi disk transparency, dissolved oxygen and pH in the formation of clusters. The results are in consonance with the Principal Component Analysis of the whole lake data and individual clusters, which showed that the variance is maximally explained by the ionic component (46.82%) followed by dissolved oxygen and pH (9.36%), nitrates and phosphates (7.33%) and Secchi disk transparency (5.98%). Spatial variability of the hydrochemistry of the lake is due to the variations in water depth, lake water dynamics, flushing rate of water, organic matter decomposition, and anthropogenic pressures within and around the Dal lake ecosystem. Overall, the water quality of the lake is unfit for drinking due to the presence of coliform bacteria in the lake waters.     

洪泽湖水沙变化趋势和冲淤时空分布及驱动因素

为了研究洪泽湖水沙特性、变化趋势与冲淤时空分布规律,运用累积距平法、Mann-Kendall趋势与突变检验以及R/S分析法等方法,分析了洪泽湖19502016年的水沙特征;采用地理信息技术,基于1992年和2016年实测地形,对湖区泥沙冲淤空间分布进行了定量计算与分析.结果表明,入湖径流量无明显增加或减少的趋势,输沙量和含沙量呈明显减小趋势,1990年以后含沙量基本稳定在0.2 kg/m^3以下;淮河干流(包括池河)入湖水量和沙量约占入湖总量的89.6%,三河闸出湖水沙占总出湖量的60%.淮干入湖口和溧河洼为主要淤积区域,淤积量分别为2300×10^4和1900×10^4 m^3,平均淤积厚度分别为0.35和0.25 m;其他区域自然冲淤基本平衡.上游水库和河道闸坝的拦沙作用、农业种植结构变化和水土保持、大规模人工采砂等是入湖沙量减少的主要影响因素;湖区水动力特性是泥沙自然淤积主导因素,而湖区库容变化的主因则是人工采砂、围湖造田和围网养殖,且人类活动的影响远大于自然冲淤.     

Dynamics of phosphorus in sediments of a naturally acidic lake

The mechanisms which controls the fixation and/or release of P in sediment of an extremely acidic lake（pH = 2.0 to 3.0） and its response to the influence of eutrophic urban waste water were investigated.The results,in the chemical composition,in the mineralogy of the sediment and in the material as obtained from sediment traps,show that the lake sediments are mainly volcanic material reflecting volcanic features of the basin.The sedimentation rate calculated for the lake(2.5×10^-2 mg m^-2 day^-1) was higher than that observed in other similar glacial lakes in both Andean Patagonia and also elsewhere in the world.The Total Phosphorus concentration in sediments was higher than figures reported by other authors for mining acid lakes,and the main fraction of P was found associated with organic matter.There was no control by Fe or Al on P,because both are in solution at pH < 3.0.It was concluded that changes in the natural input of nutrients（derivatives of Copahue volcano fluid,the discharge of sewage,or basin run-off） are responsible for a high concentration of SRP and N-NH₄⁺ in the lake.Laboratory experiments showed that sediments have no ability to retain phosphorus and a continuous release of P from the sediments into the water column was observed.The assays where the pH was artificially increased showed that the P still remains in solution until at least pH 7.0.It was concluded that changes in the natural input of nutrients due to:1) the volcanic fluids,2) the increase in sewage charges,or 3) surface runoff upstream,maintain a high trophic state with high concentrations of dissolved P and N-NH₄⁺,although the threshold of neutral pH in the lake is exceeded.This study will enable a better understanding about of the mechanism of release/fixation of phosphorus in acidic sediments in order to assist in making decisions regarding the conservation and management of this natural environment.     

湖泊水体微生物四醚膜脂化合物研究进展

来源于微生物膜脂的甘油二烷基甘油四醚类(GDGTs)化合物是近年来被广泛用于古环境定量重建研究的化合物之一,究其原因在于此类化合物对环境响应敏感,特别是温度与pH值等,据此而建立的一系列GDGTs指标有效定量重建海洋、湖泊、泥炭以及土壤等不同沉积载体的环境信息.目前已在全球范围广泛开展湖泊沉积物GDGTs的研究工作,相继建立的全球以及不同区域尺度的湖泊沉积物GDGTs校正方程,已被用于湖泊古环境的定量重建研究,有效记载古湖泊环境变迁信息.相较之下,基于湖泊水体GDGTs的调查工作则起步较晚,但越来越多的研究显示,不同类型湖泊水体普遍贡献GDGTs,然而究竟此类水生来源GDGTs是否与陆源以及湖泊沉积物GDGTs具有类似的分布,以及他们对环境因素的响应如何,这都为湖泊古温度定量重建研究带来不确定性.基于此,本文总结这10年来湖泊水体GDGTs研究工作的进展,首先阐述湖泊水体不同来源(古菌以及细菌)GDGTs的分布情况,研究发现水体不同层位GDGTs浓度以及各组分之间存在差异,并且水深在不同湖泊对GDGTs浓度以及各组分相对比例的影响存在差异.此外还总结湖泊水体中古菌来源isoGDGTs以及细菌来源brGDGTs的生物来源,并进一步分析环境因素对不同深度水体GDGTs分布的影响,虽然温度依然是影响水体中GDGTs分布的首要因素之一,然而湖泊水深、温度以及水体中溶解氧浓度等因素存在着一定的耦合关系,这些因素往往协同作用于水体GDGTs,因此会为评估环境因素对水体GDGTs的影响带来难度.     

Physico-chemical and nutrient variable stratifications in the water column and in macroalgal thalli as a result of high biomass mats in a non-tidal shallow-water lagoon

A field study to check parameter stratification during high density growth of four opportunistic macroalgae was carried out in Orbetello lagoon (Italy). The effects of macroalgal masses were compared with a seagrass meadow and two lagoon areas with bare bottoms as controls for pH, temperature, dissolved oxygen, salinity, nitrite, nitrate ammonium and orthophosphate. The nutrient content of thalli and sediment redox were measured. Macroalgae showed differences in stratification of thalli nutrient content. Mat with low density and high volume produced stratifications in the water column, but it did not produce nutrient release by sediment. In contrast, high density and low and high volume mats led to sharp falls in dissolved oxygen, with negative values of sediment Eh and anoxic trigger processes that presumably led to release of sediment nutrients. This depended on thallus type: heavy thalli compacted the mat and light ones distributed more widely in the water column.     

Rotifer abundance, biomass, and secondary production after the recovery of hydrologic connectivity between a river and two marginal lakes (São Paulo, Brazil)

Rotifera density, biomass, and secondary production on two marginal lakes of Paranapanema River were compared after the recovery of hydrologic connectivity with the river (São Paulo State, Brazil). Daily samplings were performed in limnetic zone of both lakes during the rainy season immediately after lateral inflow of water and, in the dry period, six months after hydrologic connectivity recovery. In order to identify the factors that affect rotifer population dynamics, lake water level, volume, depth, temperature, transparency, dissolved oxygen, pH, alkalinity, conductivity, suspended solids, nutrients, and chlorophyll-a were determined. Variations of water physical and chemical factors that affect rotifer population were related to the lake-river degree of connection and to water level rising after drought. The water lateral inflow from the river resulted in an increase in lake water volume, depth, and transparency and a decrease in water pH, alkalinity, and suspended solids. The lake with the wider river connection, more frequent biota exchange, and larger amount of particulate and dissolved materials was richer and more diverse, while rotifer density, biomass, and productivity were lower in both periods studied. Density, biomass, and secondary production were higher in the lake with the smaller river connection and the higher physical and chemical stability. Our results show that the connectivity affects the limnological stability, associated to seasonality. Stable conditions, caused by low connectivity in dry periods, were related with high density, biomass and secondary production. Conversely, instability conditions in rainy periods were associated to elevated richness and diversity values, caused by exchange biota due to higher connectivity.     

Apparent redox potential discontinuity (aRPD) depth as a relative measure of sediment oxygen content and habitat quality

As hypoxic conditions spread in our oceans, indices that quickly and efficiently assess oxygen content in sediment pore water, and habitat quality are increasingly becoming desirable. Depth to the appa...     

Experimental study on phosphorus release from sediments of shallow lake in wave flume

Influence of wave on sediment resuspension and nutrients release from sediments, collected from Lake Taihu and Lake Chaohu, was studied in flume experiments. Under strong-wave conditions, concentrations of suspended solids (SS), total phosphorus (TP) and dissolved total phosphorus (DTP) in overlying water were increased significantly following the sediments re-suspension. During the experiments on sediments of Lake Taihu and Lake Chaohu, TP concentrations increased 6 times and 3 times, and DTP concentration increased 100% and 70% more than it in presuspension, respectively. Concentration of soluble reactive phosphorus (SRP) of experiment on sediment of Lake Taihu increased 25%. During the massive sediment suspension, the dissolved phosphorus in pore water and much of the phosphorus adsorbed by the sediment particles were released into overlying water. The phenomena in this wave flume experiment are quite similar to the situation observed in situ of Lake Taihu. The critical wave stresses of sediment re-suspension are nearly equal. The change of concentrations of SS, TP, and SRP was the same as that in situ situation. This study showed that concentrations of TP and SRP in lake water could be increased significantly by wave disturbance. Phosphorus release was significantly enhanced by wave disturbance at the beginning of massive sediment re-suspension, but decreased later.