大亚湾大辣甲水域溶解无机碳垂直分布特征及季节动态

于2007年10月～2008年9月进行了4个季节的垂直采样监测,对大亚湾大辣甲水域溶解无机碳(DIC)的垂向分布和季节动态特征进行了研究,分析了大亚湾溶解无机碳与各环境要素(pH、水温、溶解氧和叶绿素a等)的相关性。结果表明:在春、秋和冬季,大亚湾大辣甲水域DIC含量在垂直分布上差异较小,但夏季(2008年7月)变化较为显著,DIC含量的变化范围为16.79～26.52mg·L^-1;DIC高值基本集中在中、底层水域(8～16m),尤以底层水域(13～16m)为甚;DIC含量基本呈现出春、夏季较高,秋、冬季较低的分布趋势;DIC含量与pH值和水温含量显示出了负相关关系,而与盐度呈正相关关系。     

大亚湾表层水中溶解无机碳的时空分布

于2010 年12 月～2011 年11 月分4 个季度,对大亚湾海域进行了采样调查,分析了大亚湾表层水体中溶解无机碳(Dissolved inorganic carbon, DIC)含量的时空分布特征,并讨论了大亚湾表层水DIC 与pH、盐度、水温和叶绿素a 等环境因子之间的关系。大亚湾海域表层水DIC 含量的变化范围为19.49～23.20 mg·L^-1,均值为21.13±1.07 mg·L^-1,较黄海及东海水域的DIC 含量低。DIC 的水平分布大致呈现出西部及西北部海域高于东部及湾口海域的趋势。大亚湾表层水DIC 含量呈现出冬季>夏季>秋季>春季的季节变化趋势,但春、夏及秋季差异不大。大亚湾海域表层水的DIC 含量除与盐度呈现了显著的正相关关系外,与pH 值、水温及叶绿素a 显示出负相关,但不显著。大亚湾海域DIC 的时空分布特征是多种因素综合作用的结果,其同时受季风、水温、盐度、水动力、生物地球化学和生物等因子的影响。     

白洋淀湿地水华暴发阈值分析

水体富营养化阈值分析可为控制水华暴发,确定合理的污染物控制水平提供科学依据.以白洋淀湿地为例,利用2000-2009年水质监测数据,选择表征水体富营养化的主要指标进行主成分聚类分析,划分出低溶氧高营养型和不稳定型2类水域;并针对不同水域类型,以叶绿素a为因变量,以pH值、水温、透明度(SD)、CODcr、总氮(TN)、总磷(TP)、氨氮、硝氮和溶解态无机磷为自变量,采用逐步回归方法,分别建立了水质指标与叶绿素a的多元线性关系式,以此确定了白洋淀湿地水体水华暴发阈值.根据叶绿素a为30μgL-1为水华暴发的临界值,白洋淀低溶氧高营养型水域CODcr应控制在37.31mg·L-1,不稳定型水域TP应控制在0.12mg·L-1.     

河道型水库溶解无机碳同位素组成特征与来源——以万安水库为例

以江西万安水库为研究对象,于2014年9月至2015年6月进行4次季节性采样,对该区域9处采样点的溶解无机碳(DIC)及其同位素(δ13CDIC)进行分析。结果表明:夏、秋季DIC含量较春、冬低;δ13CDIC也较冬、春季偏负。DIC含量从上游到下游呈下降趋势,碳同位素值则趋于偏正。光合作用与有机质分解是影响库区表层水体δ13CDIC值变化的主要因素。垂直剖面上,表、底层水温等参数差异不显著,上下水体混合较为均匀。DIC含量基本上随深度的增加而增大,δ13CDIC值趋于偏负。利用质量平衡计算得出:入库水体中DIC约57%来自于土壤CO2,而坝下水体中DIC约49%来自土壤CO2,万安水库拦截对河流地球化学过程信息有一定的改造作用。     

大亚湾溶解有机碳的时空分布

于2010年12月～2011年11月分4个季度,在大亚湾海域布设9个采样点采集海水样品,用于溶解有机碳的测定,通过高温催化氧化法完成样品的分析。结果表明,大亚湾海域表层水DOC含量的变化范围为0.953～2.109 mg·L^-1,均值为1.369mg·L^-1,高于大洋的平均值,具有典型近海特征。DOC的水平分布大致呈现出靠近陆域(尤其是靠近澳头一侧)的含量较高,大辣甲西侧及西北侧水域较低的分布特征。大亚湾DOC含量呈现出夏季>秋季>春季>冬季的季节变化趋势。大亚湾DOC含量与浮游植物数量和浮游动物干重不具有明显的线性相关,表明生物作用对DOC含量分布趋势影响并不明显,大亚湾DOC含量可能还受到人类活动和水动力学等的影响。     

胶州湾典型河口湿地土壤溶解性无机碳分布特征

选择胶州湾大沽河与洋河河口湿地作为研究区,在平行于海岸带方向的光滩和垂直于海岸带方向的河漫滩分层采集土壤样品,测定土壤溶解性无机碳(DIC)含量、相关离子含量及土壤理化性质.应用Duncan方法及Pearson相关分析法进行分析,探讨土壤DIC分布特征及影响因素.结果表明: 光滩土壤DIC含量总体呈现距入海口越远含量越高的趋势,水体的冲刷作用是导致河流入海口处土壤DIC含量最低的主要原因.河漫滩土壤DIC含量总体呈现随距海距离增加而先降低后升高的趋势,主要是受人类活动等综合因素的影响.互花米草入侵使土壤DIC含量明显降低,这是入侵物种根系的转化作用所导致的.养殖活动改变了养殖池塘自身的环境因子,进而改变了土壤DIC分布规律,表现为表层土壤DIC含量高于光滩而其余土层略低于光滩.相关性分析表明,土壤DIC含量与土壤含盐量及总无机碳含量呈显著正相关、与土壤pH呈显著负相关.     

大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化

为了较为系统地研究大亚湾水域叶绿素a和营养盐的垂直分层状况, 并为大亚湾海洋生态系统的数值模拟提供基础数据, 作者于大亚湾大辣甲和桑洲之间连线的中间点附近海域选点, 在2007年～2008年进行了4个季度的垂直采样监测。本次研究分析了大亚湾大辣甲水域叶绿素a及营养盐的垂直分布与季节变化, 并分析了叶绿素a与DIN、PO₄-P和SiO₃-Si的关系。结果表明:在整个监测时段内, 叶绿素a和DIN、PO₄-P、SiO₃-Si的浓度范围分别为0.50～5.80 mg·m^-3、0.023～0.159 mg·L^-1、1.606～19.69μg·L^-1和0.065～1.13 mg·L^-1, 营养盐和叶绿素a在4个季度里的垂直变化趋势各有不同;在季节变化上, SiO₃-Si与DIN比较相似, 总体呈现夏、冬、秋季高, 春季较低的特征, PO₄-P恰好相反, 夏季的浓度最低, 叶绿素a总体呈现夏、春、冬季高, 秋季较低的特征;在整个垂直水柱内, DIN和SiO₃-Si对叶绿素a的影响相对较小, PO₄-P和叶绿素a呈显著正相关关系。     

胶州湾叶绿素a浓度及浮游植物的粒级组成

2008年2、5、8和11月对胶州湾及邻近水域中表层叶绿素a浓度和浮游植物粒级组成进行了调查.结果表明:胶州湾内和湾外表层叶绿素a年平均浓度分别为4.90和2.03 mg·m^-3;叶绿素a浓度的平面分布呈现自东北部及近岸向中部、南部及湾外递减的趋势;叶绿素a浓度季节变化明显,冬季和夏季浓度较高,春季次之,呈现温带海域双峰型的变化趋势.胶州湾浮游植物粒级组成以微型浮游植物为主,平均占叶绿素a总量的60.9%,其次是小型浮游植物,超微型浮游植物所占比例最低,与我国近海浮游植物粒级组成基本一致.与历史资料相比,微型浮游植物所占比例有所增加,超微型浮游植物所占比例降低.     

夏季达里诺尔湖浮游细菌群落表、底层结构特征及其关键驱动因子

浮游细菌是湖泊水体物质循环和能量流动过程中的关键要素, 影响着整个生态系统的迁移转化。为探索中国北方典型内陆封闭型湖泊浮游细菌群落结构对环境因子变动的响应, 以夏季内蒙古达里诺尔湖(以下简称“达里湖”)为例, 采集表、底层水共32个样品, 基于16S rRNA基因测序, 详细分析了浮游细菌群落结构的表、底层变化特征及其主要影响因素, 结果显示: (1)夏季达里湖水体中浮游细菌群落多样性和均匀度均呈现表层＞底层, 丰富度则呈底层＞表层。(2)浮游细菌群落以变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、蓝细菌门(Cyanobacteria)和拟杆菌门(Bacteroidetes)四大优势菌门为主要组成部分, 且变形菌门含量在表、底层水体中均占绝对优势: 在底层水中占比46.46 %, 在表层水中占比36.21 %。(3)基于不同环境因子和浮游细菌优势菌门间的Pearson相关性分析, 表层水体中总溶解性固体(TDS)、溶解态无机磷(DIP)是多数优势菌门的主要驱动因子, 而底层水体中的总氮(TN)、叶绿素a(Chl a)和水温(WT)为主要驱动因子。总的来说, 达里诺尔湖表、底层浮游细菌群落结构与不同环境因子间存在显著相关, 而水体环境因子的表、底层差异是影响多数优势菌门演化的重要因素。     

菹草种群内外水质日变化

对菹草(Potamogeton crispus)种群内外水体进行了昼夜连续监测,分析菹草种群内外水质的日变化趋势.结果显示,种群内DO自日出后增加,日落后持续下降,且与水温变化一致,于19:30左右出现1次明显低谷,后略有恢复,后一直降至日出前后;开阔水域DO变化与水温呈现一定相关性,但变化幅度较小;交界处DO含量兼有种群内与开阔水域的变化特点.种群内水体pH值自日出前后升高,日落时达最高值,后开始下降,直至次日出前后;交界处与种群变化趋势一致;开阔水域pH总体变化幅度较小,白天高于夜间,总体DO含量及pH分布:种群区＞交界处＞开阔水域.种群及交界处TN含量均在日出前后达最高,日出后递减,开阔水域夜间含量较高,日出前后达最高;各点NH+4-N变化规律不显著;种群内水体TP含量夜间较高,日出前后达最高值,日出后递减,日落后递增;开阔水域TP含量夜间较高,白天略低;交界处正午前后达最低值,傍晚达最高值,TN、TP总体分布:种群＜交界处＜开阔水域.菹草种群存在对水体DO、pH等环境因子均产生重要影响,继而影响水体内源性氮磷的迁移,其中对pH影响较小,其变化未能影响水体氮磷迁移,而DO昼夜变化较大,对水体内源性氮磷的迁移起重要影响.     

海州湾及邻近海域冬季鱼类群落结构及其与环境因子的关系

根据2011年冬季在海州湾及邻近海域进行的渔业资源底拖网和环境调查数据,应用物种多样性指数和多元分析等方法,对该海域鱼类种类组成、多样性和群落结构及其与环境因子的关系进行了研究.结果表明: 该海域冬季捕获鱼类共60种,隶属于10目34科51属,以暖温性和暖水性底层鱼类为主.站位间物种丰富度指数介于1.14～2.84,多样性指数介于1.08～2.64,均匀度指数介于0.41～0.83之间.经聚类分析和非度量多维标度(MDS)分析,该海域鱼类群落在空间上可分为站位组Ⅰ(35° N以北水域站位)、站位组Ⅱ(靠近湾顶的近岸水域站位)和站位组Ⅲ(35° N以南水域站位).鱼类群落种类组成在站位组间及两两间的比较均差异极显著(R=0.45～0.91).典范对应分析表明,底层水温、水深和表层盐度是影响海州湾及邻近海域冬季鱼类群落结构的主要环境因子.     

浙江披山海域主要虾蟹类时空生态位及种间联结性

根据2015年11月(秋季)、2016年2月(冬季)、5月(春季)、8月(夏季)在浙江披山附近海域进行的渔业资源调查数据,运用生态位测定、方差比率、χ²检验、Spearman检验和冗余分析等方法,研究了该海域主要虾蟹类的时空生态位特征和种间联结关系。该海域共鉴定出虾蟹类34种,隶属于14科20属,4个季节均出现的有10种,优势种为哈氏仿对虾、脊尾白虾和三疣梭子蟹。主要虾蟹类时间、空间和时空生态位宽度范围分别为0.03～1.34,2.07～3.63和0.08～4.64。生态位宽度聚类分析显示,在90%的相似性水平下,主要虾蟹类可分为窄、中、宽3个生态位宽度种组。此外,披山海域主要虾蟹类时空生态位重叠程度以低等级为主(68.9%的种对Q_ik值＜0.3),物种间对资源利用竞争不大。方差比率分析表明,主要虾蟹类总体以正联结性为主,其中11.1%的种对正联结关系显著。JI指数、OI指数和Spearman检验均显示,披山海域主要虾蟹类种间联结性在整体上趋于正相关。冗余分析表明,表温、底温和表盐是影响披山海域主要虾蟹类分布的主要环境因素。     

Primary production in a tropical fish pond at Aligarh,India

Summary Seasonal fluctuations in gross and net primary production values were quite apparent in surface waters and showed a bimodal type of distribution. The values were generally high during post winter months (March to May) and low during winter (February) and monsoon months (July and August). At different depths the rate of primary production was always found decreasing from surface to bottom. The rate of photosynthesis was found to be highly variable from time to time and at different depths.Respiratory rate was found to be increasing from surface to bottom perhaps due to decomposition of organic matter and high bacterial growth at the increasing depths. A close relationship was found between the transparency and primary production values. Phosphate-phosphorus was found to be directly related with the gross primary production values. However, there was no relationship between nitrate-nitrogen and production values. An inverse relationship was shown between ammonia-nitrogen and the production values. Fluctuations in chlorophyll were also found significantly related with the gross primary production.     

Anoxia in a coastal bay: case study of a seasonal event

Bahía Concepción (Gulf of California) was studied to describe some extremely low dissolved-oxygen values at the bottom of the bay. Surveys included measurements of vertical distribution of temperature, dissolved oxygen, nitrate, nitrite, phosphates and hydrogen sulfide. Thermal stratification from early spring to autumn and a well-mixed water column during the winter were present. Dissolved-oxygen concentration was homogeneous in the water column from winter to spring (5-7 mg L-1). From summer to autumn, bottom dissolved oxygen (> 20 m) decreased to reach conditions of hypoxia (1-2 mg L-1) or anoxia; nitrate, nitrite, and phosphates increased (up to 13, 1.7 and 2.2 microM) followed by a last short period of a deep hydrogen sulfide layer (up to 3.1 mg L-1). A back calculation to estimate the input of organic matter in the deep layer showed that 18 g C m-2 y-1 needed to be trapped in the bottom to induce such an oxygen depletion. This period is thought to be unfavorable for bottom infauna in this bay.     

Heavy metals in the Rosetta estuary of the Nile and the adjoining Mediterranean waters: evidence of removal of dissolved heavy metals from waters as a result of possible binding to suspended matter

The Rosetta estuary was partially separated from the Rosetta branch of the Nile by Edfina Barrage, which controls the Nile discharge into the Mediterranean Sea. The study area covers the Rosetta estuary (lotic environment) and the adjoining seawaters (lentic environment) to investigate the local and seasonal distribution of dissolved and particulate copper and zinc, as well as dissolved cadmium in this estuary and to illustrate its influence on the distribution of these metal forms in the inshore seawaters. Besides, emphasis on the removal of dissolved heavy metals from waters by their adsorption onto suspended matter (SM) was also considered. Contrary to particulate copper (PCu), the vertical values of dissolved copper (DCu) decreased generally with depth. Planktonic scavenging and regeneration processes might determine the vertical profiles of the copper forms. The copper data suggest that the surface sources of DCu exceeded the bottom sources, contrary to the sources of PCu. The markedly high and maximum seasonal averages of DCu in the estuary and inshore seawater in July inspite of the high uptake in summer possibly reflect higher amounts of humic materials. The lowest seasonal average value of DCu in the inshore seawater in January suggests removal of copper in presence of maximum value of SM during highest discharge. The highest regional average of DCu at the estuarine mouth coincided with desorption process during mixing of the fresh and salt waters. The vertical values of dissolved zinc (DZn) and particulate zinc (PZn) showed irregular variations and their high concentrations in the surface of the estuarine and inshore seawater indicate possible land-based sources. The high bottom DZn values, however, resulted from its contribution from the interstitial water of the sediments. The data suggest that the surface sources of DZn exceeded the bottom sources and PZn showed the opposite trend in the open sea area. In the estuary, the maximum seasonal average value of DZn accompanied by the lowest seasonal average of PZn in April inspite of the high uptake in spring suggest that desorption was the dominant process. The minimum regional averages of both zinc forms at the estuarine opening and the highest average of PZn near Edfina Barage are correlated with the amounts of SM, which decreased toward the estuarine mouth. The vertical values of dissolved cadmium (DCd) were much lower in the estuary than the other metals. They showed in both environments irregular variations with depth. The bottom maximum value of DCd can be attributed mainly to contamination from the sediments. There was a distinct seasonal variation of DCd. The minimum seasonal average value of DCd in the estuary in April seems to be caused by its specific binding to living plankton found in abundance. The minimum regional average of DCd value was found at the estuarine mouth. The decrease in Cd concentration due to removal from dissolved state is most pronounced in the early stage of mixing. The correlation coefficients of DCd were positive with salinity and negative with SM, indicating that Cd increased seaward. Statistical correlation between Cd and Zn concludes that the factors affecting their distribution are generally the same.     

Evaluation of mercury level in waters, bottom sediments and soils in selected rural areas

The studies carried out aimed at evaluation of the mercury level in waters, bottom sediments and soils in selected rural areas, during the season of mercury biocides application and after their withdrawal from agricultural use. Generally, in the period between 1976-1980 the mercury level in 1268 environmental samples has been examined. Shallow dug wells of bad technical state and wrong location particularly exposed to contamination, have been selected for the studies. Mercury level has been determined after mineralization with concentrated acids by means of flameless method of atomic absorption spectrophotometry. The results have been compared with standards for mercury level in drinking waters (1 microgram/l) and in surface waters (5 micrograms/l), with the Warren-Devault criterion for soils (0.25 mg/kg) and with the value 1 mg/kg adopted as maximum natural mercury level in bottom sediments. The results have also been the subject to statistical analysis by means of the Tsao-Fei method and t-test. Mercury level in well waters, surface waters, bottom sediments and soils varied according to the region and the year of study and were respectively: 0.08-26.00 micrograms/l; 0.00-25.20 micrograms/l; 0.02-91.91 mg/kg; 0.01-24.94 mg/kg. Mercury levels of several dozen micrograms/l (waters) and several dozen mg/kg (bottom sediments and soils) have been recorded only in a few cases. A statistically significant decrease of mercury level in the environment of the regions investigated coincided with mercury biocides withdrawal from agricultural practice in our country.     

Aquatic Hyphomycetes in Polluted Groundwater Habitats of Central Germany

Polluted groundwater wells located in a former copper shale mining district (11 sites; Mansfelder Land, Central Germany) and in meadows of the Mulde and Elbe rivers (2 sites) were assessed for occurrence and species richness of aquatic hyphomycetes. Water temperatures at all sites were relatively low and fluctuated less than in surface waters. Oxygen concentrations were always below saturation, whereas sulfate, nitrate, and phosphate levels reached extremely high values in several of the wells. Relatively high levels of Pb, Mn, and Fe were found in some of the wells, but overall few concentrations of individual metals and metalloids exceeded European guidelines for drinking water. Pollen tube growth inhibition, used to assess cytotoxicity of the water, ranged between 4 and 50%. Between 1 and 10 distinct species of aquatic hyphomycetes colonized sterile Alnus glutinosa leaves exposed at the Mansfelder Land sites; for the meadow sites, 8-20 species were found. Heliscus lugdunensis and Anguillospora sp. were the two most widespread species. Fungal colonization occurred much more slowly than in surface water, as demonstrated by scanning electron microscopy and the release of conidia from recovered leaves. The conidial output from exposed alder leaves ranged from 0.2 to 95 conidia mg (-1) dry mass, corresponding to 10% of the values for contaminated surface waters in the same region. Overall, groundwater appears to be a marginal habitat for aquatic hyphomycetes, but may nevertheless play a vital role as long-term reservoir facilitating rapid recolonization following a collapse in fungal communities in surface waters.