Distribution and Fractionation of Arsenic in Selected Fresh Water Lake Sediments

The distribution and nature of the As-bearing components of the sediments of selected fresh water lakes in Saskatchewan, Canada, were studied. The total As contents ranged from 2.7 to 13.2 ppm As and were found to be present in both colloidal and non-colloidal fractions of the lake sediments. The proportion of the As bound to carbonates, organic matter and sesquioxides accounted for 12 to 74% of the total As of the sediments. The remaining As was apparently associated with apatite and silicates. The data indicate that the bulk of As in the lake sediments resides in sesquioxidic components and apatite. The release of As from the lake sediments would thus be affected by the stability of these As-bearing components in a series of particle size fractions. Furthermore, based on information on the geographical distribution of As in the lake sediments, land erosion and agricultural runoff appear to be contributing significantly to the As concentration in lake sediments. It is thus suggested that close attention should be paid to land management and soil conservation to prevent further enrichment of As in lake sediments and to curtail the subsequent As contamination of the food chain.     

Simultaneous Monitoring of Phosphine and of Phosphorus Species in Taihu Lake Sediments and Phosphine Emission from Lake Sediments

Phosphine (PH₃) was monitored in the Taihu Lake in China by a GC/NPD method, coupled with cryo-trapping enrichment technology. Results showed that PH₃ was universally detected in sediments, lake water and atmosphere of the Taihu Lake area. Total phosphorus (TP_s) and fractions of different phosphorus species in lake sediments were separately measured as dissolved phosphate (DP), phosphorus bound to aluminum (Al-P), iron (Fe-P) and calcium (Ca-P), occluded phosphorus (OP), and organic phosphorus (Org-P) by sequential chemical extraction. High PH₃ levels were correlated with high TP_s values in sediments and with eutrophication at different sites. In addition, a positive linear correlation equation was obtained between the concentrations of PH₃ in lake sediments and of the phosphorus fractions. The resulting multiple linear regression equation is PH₃ = −165 + 63.3 DP + 0.736 Al-P + 2.33 Ca-P + 2.29 Org-P. The flux of PH₃ across the sediment–water interface was estimated from sediment core incubation in May and October 2002. The annual average sediment–water flux of PH₃ was estimated at ca. 0.0138±0.005 pg dm⁻² h⁻¹, the average yearly emission value of PH₃ from Taihu Lake sediments to water was calculated to be 28.3±10.2 g year⁻¹, which causes a water PH₃ concentration of up to 0.178±0.064 pmol dm⁻³. The real importance of PH₃ could be higher, because PH₃ could be consumed in the oxic sediment–water boundary layer and in the water column. Spatial and temporal distributions of total phosphorus (TP_w) and chlorophyll a (Chl-a) in the water column of Taihu Lake were measured over the study period. Higher water PH₃ has also been found where the TP_w content was high. Similarly, high Chl-a was consistent with higher water PH₃. Positive relationships between PH₃ and TP_w (average R² = 0.47±0.26) and Chl-a (average R² = 0.23±0.31) were observed in Taihu Lake water.     

Differences between Betaproteobacterial Ammonia-Oxidizing Communities in Marine Sediments and Those in Overlying Water

To assess links between betaproteobacterial ammonia-oxidizing bacteria (AOB) in marine sediment and in overlying water, communities in Loch Duich, Scotland, were characterized by analysis of clone libraries and denaturant gradient gel electrophoresis of 16S rRNA gene fragments. Nitrosospira cluster 1-like sequences were isolated from both environments, but different sequence types dominated water and sediment samples. Detailed phylogenetic analysis of marine Nitrosospira cluster 1-like sequences in Loch Duich and surrounding regions suggests the existence of at least two different phylogenetic subgroups, potentially indicative of new lineages within the betaproteobacterial AOB, representing different marine ecotypes.     

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration.Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release.The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations.     

鄱阳湖黄鳝的生长特征

以基舌骨和脊椎骨作为年龄鉴定的材料,研究了鄱阳湖黄鳝(Monopterus albus)种群的生长特征.结果表明,种群的年龄结构分别为:雌性1～5龄,雄性2～6龄,2～5龄为黄鳝性别的过渡期(间性).2～4龄为优势年龄组,占渔获物的89.75%,相对应的体长为30～50 cm,体重为30～120 g.体长(L)与体重(W)的关系为:W=0.000 4L3.2601(♀);W=0.001 4L2.9008(∮).按生长指标值分析,阶段生长可以明显地划分为两个时期,即2龄前的生长迅速期和2龄后的生长稳定期.拟合的Von Bertalanffy生长参数分别为雌性L∞=78.5 Cm,k=0.174 02/y,t0=-1.203 2 Y,W∞:602.01 g;雄性L∞=102.3 cm,k=0.118 45/y,t0=-1.310 1 Y,W-=947.32 g;生长特征参数分别为ψ=3.030 3(♀)和ψ=3.093 4(∮);雌雄个体生长差异显著.     

鄱阳湖保护区白琵鹭越冬种群分布

2007年10月至2010年3月3个冬季的调查显示,鄱阳湖国家级自然保护区白琵鹭(Platakakucorodia)种群数量在12月或1月达到峰值,3个越冬期最大种群数量分别为4 757只、10 385只和7 268只.大湖池、沙湖、常湖池是白琵鹭主要的栖息地,每个越冬期在这3个湖泊栖息的白琵鹭种群数量占保护区总数量的...     

菹草对湖泊沉积物磷状态的影响

武昌野芷湖湾菹草(PotamogetoncrispusL.)生物量较高位置的沉积物显示明显较高的磷吸附指数,以及据Langmuir方程:C/X=C/Xm+K×1/Xm导出的最大吸附量与吸附强度,这一结果在不同时期与不同采样深度均有体现,故提高沉积物磷的吸附能力应为菹草维持水体较低营养水平的重要机制。铁结合态磷是沉积物磷的主要存在形式,吸附能力的提高可由有机质及其与铁的相互作用部分地得到解释。不同时期菹草生物量较高的沉积物表现明显较低的碱性磷酸酶活性与最大反应速度,降低沉积物有机磷的酶促分解速率应为菹草维持水体低营养水平的另一机制。     

Influence of Submerged Plants on Phosphorus Fractions and Profiles of Sediments in Gucheng Lake

To understand the effect of submerged macrophytes on P in sediment, P fractions in the surface sediments (0–20 cm) of Potamogeton crispus, Potamogeton maackianus and non-vegetated areas were investigated. In the submerged macrophytes areas, the concentrations of HCl-P, NaOH-P, IP, OP and BD-P were significantly lower than in the non-vegetated area. NH₄Cl-P did not differ significantly among areas.

In the submerged macrophyte distribution areas, TP was significantly correlated with IP and OP. However, in the non-vegetated area, TP was significantly correlated with NH₄Cl-P and OP. In all of the areas sampled, IP was the major phosphorus fraction in the sediments, which consists largely of NAOH-P and HCl-P. The decreasing order of P fractions was: IP > HCl-P > NaOH-P > OP > BD-P > NH₄Cl-P. These results show that submerged macrophytes can decrease the concentrations of all P fractions and imply that submerged macrophytes play a key role in the retention of P nutrients.     

Bacterial Diversity and Distribution in the Holocene Sediments of a Northern Temperate Lake

Sediments contain an abundance of microorganisms. However, the diversity and distribution of microorganisms associated with sediments are poorly understood, particularly in lacustrine environments. We used banding patterns from denaturing gradient gel electrophoresis (DGGE) and 16S rDNA sequences to assess the structure of bacterial communities in the Holocene sediments of a meromictic lake in Minnesota. Cluster analysis of the DGGE banding patterns indicates that the early- and middle-Holocene samples group separately from the late-Holocene samples. About 79% of the recovered bacterial sequences cluster with the α-, β-, δ-, ɛ-, and γ- Proteobacteriaceae and Firmicutes. The remaining ∼21% lack cultured representatives. The taxonomic lineages of bacteria differ statistically among the early-, middle-, and late-Holocene samples, although the difference is smallest between early- and middle-Holocene samples. Early- and middle-Holocene samples are dominated by ɛ-Proteobacteriaceae, and late-Holocene samples are dominated by sequences from uncultured subphyla. We only recovered δ-Proteobacteriaceae in late-Holocene sediments and α- and γ- Proteobacteriaceae in late- and middle-Holocene sediments. Diversity estimates derived from early-, middle-, and late-Holocene clone libraries indicate that the youngest (late-Holocene) samples had significantly greater bacterial diversity than the oldest (early-Holocene) samples, and the middle-Holocene samples contained intermediate levels of diversity. The observed patterns of diversity may be caused by increased bacterial niche-partitioning in younger sediments that contain a greater abundance of labile organic matter than older sediments. D. M. Nelson and S. Ohene-Adjei contributed equally to this work     

Distribution of Exopolymeric Substances in the Littoral Sediments of an Oligotrophic Lake

Bacteria and algae release exopolymeric substances (EPS) that perform a wide range of important functions in aquatic and terrestrial systems. In this study we measured EPS in sediments at nine littoral sites around a shallow oligotrophic basin, and tested whether the concentration and composition of EPS was related to sediment characteristics. The concentrations of both loosely bound (colloidal) and tightly bound (capsular) EPS carbohydrates ranged up to ~800 µg glucose equiv. cm^–2 and were well within the range of concentrations reported from marine intertidal flats, where EPS play an important role in stabilizing sediments, affecting nutrient exchanges between sediments and the water column, feeding benthic invertebrates, and sequestering and increasing the transfer of contaminants to food webs. Proteins were an important component of the EPS in these littoral sediments, with protein:carbohydrate ratios of ~0.4. In summer, the concentrations of most EPS fractions were positively related (P < 0.05) to the porewater and organic matter content of the sediments. Capsular EPS concentrations were lower in the fall, with a simultaneous increase in colloidal proteins but not in colloidal carbohydrates. This suggests that the carbohydrates in this colloidal EPS may be more labile than the proteins. Our results suggest that exopolymeric substances could be an important, but neglected, component of littoral sediments in lakes.     

俯瞰鄱阳湖

纪伟涛的名字是与鄱阳湖的盛名联系在一起的。鄱阳湖烟波浩淼,是闻名遐尔的中国第一大淡水湖。纪伟涛从空中审视鄱阳湖珍禽候鸟的航空摄影,受到广泛关注和好评,他的作品频频在国内外刊物上     

鄱阳湖典型湿地土壤有机碳分布及影响因子

在南矶湿地国家级自然保护区设置采样带,对鄱阳湖典型湿地土壤有机碳分布及影响因子进行了研究。结果表明:1)湿地土壤0～15、15～30、30～50cm有机碳含量分别为1.07%～3.52%、0.31%～1.96%、0.27%～0.92%,有机碳含量自表层以下急剧降低。2)湿地土壤0～50cm有机碳密度变化范围为3.02～10.19kg·m-2,其中,表层0～15cm约占42.5%～72.6%;土壤有机碳含量、碳密度均以苔草植物群落最高,其他依次为南荻群落、南荻+苔草群落、芦苇群落、水蓼群落。3)土壤水分与植物生物量是鄱阳湖湿地土壤有机碳分布的2个主要影响因子,土壤水分能解释湿地表层0～15cm有机碳40%的变异,总生物量则能解释28%的土壤有机碳变异。4)鄱阳湖湿地碳密度与长江中下游地区的湖泊湿地类型具有较好的可比性,远低于若尔盖、三江平原等冷区泥炭湿地类型。     

Vertical Distribution of Ammonia-Oxidizing Archaea and Bacteria in Sediments of a Eutrophic Lake

In order to characterize the vertical variation of abundance and community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in sediments of a eutrophic lake, Lake Taihu, molecular techniques including real-time PCR, clone library, and sequencing were carried out in this study. Abundances of archaeal amoA gene (ranged from 2.34 × 10⁶ to 4.43 × 10⁷ copies [g dry sediment]^?1) were higher than those of bacterial amoA gene (ranged from 5.02 × 10⁴ to 6.91 × 10⁶ copies [g dry sediment]^?1) for all samples and both of them exhibited negative correlations with the increased depths. Diversities of archaeal and bacterial amoA gene increased with the elevated depths. There were no significant variations of AOB community structures derived from different sediment depths, whereas obvious differences were observed for the AOA community compositions. The information acquired in this study would be useful to elucidate the roles of AOA and AOB in the nitrogen cycling of freshwater ecosystems.     

Perfluorinated Compounds Distribution and Source Identification in Sediments of Lake Victoria Gulf Basin

Perfluorooctanoic acid and perfluorooctane sulfonate were determined in the sediments from Winam Gulf, which is in the Kenyan side of Lake Victoria and in its source rivers. The sources of perfluorinated compounds within the Gulf of Lake Victoria have been identified and their levels determined for the first time, in this study, using SPE and HPLC-MS-MS analytical methodology. Variability in the concentrations of perfluorooctanoic acid and perfluorooctane sulfonate ranged from 1.4–99.1 and <1–57.5 ng/g in river sediments, respectively, which was higher than concentrations obtained from lake sediments (range perfluorooctanoic acid <1–24.1 ng/g and perfluorooctane sulfonate <1–4.0 ng/g). The results obtained suggested generalized point sources such as domestic and industrial waste indicated by significant correlation and regression of r² = 0.857. Sampling sites within and near sewage and water treatment facilities gave the highest concentrations of both analytes, and were observed to be the main source of perfluorinated compounds pollution. The lowest limit of quantification was 1 ng/g for both analytes and limits of detection were 0.1 and 0.2 ng/g for perfluorooctanoic acid and perfluorooctane sulfonate, respectively. Typical values for recovery obtained were higher than 78% from spiked amounts ranging from 1 to 150 ng. Quantifying perfluoro alkylated compounds in sediments have provided insights into their source, distribution, and mobility in the Lake Victoria Basin.     

鄱阳湖越冬白鹤觅食地特征分析

2008年11月至2009年3月,采用样线法、样方法和因子分析法对鄱阳湖国家级自然保护区越冬白鹤(Grus leucogranus)觅食地特征进行了研究。结果表明,白鹤在保护区的分布具有时空动态性,主要受水位和食物的控制;白鹤对不同类型觅食地具有选择性(P0.05),对沉水植物型觅食地,即以苦草(Vallisneria natans)、黑藻(Hydrilla verticillata)、马来眼子菜(Potamogeton malaianus)为主的沉水植物型生境利用度最大;白鹤各型觅食地各因子的方差分析表明,植被因子具有极显著差异(P0.001),基底因子和掘食因子具有显著差异(P0.05);因子分析表明,觅食地选择以取食效率因子为主,其次是基底因子和食物丰富度因子。     

Distribution of Sediment Phosphorus Fractions in Hypertrophic Strongly Stratified Lake Verevi

Lake Verevi is a hypertrophic and strongly stratified (partly meromictic) small temperate lake. Vertical distribution of sediment phosphorus fractions as well as iron, manganese, organic matter and calcium carbonate of the deep bottom sediment was determined. The study focused on the ecologically important layer of the sediment [<20(45) cm]. In the uppermost layers of the sediment, NaOH-NRP (organic P) dominated while HCl-RP (apatite-P) became dominant in some deeper layers below 7 cm. Extremely high concentrations of labile phosphorus fraction (NH₄Cl-RP) indicated the low binding capacity of phosphorus by lake sediment. Due to sediment and hypolimnion anoxia, the internal load of phosphorus in this lake is most likely. Potentially mobile phosphorus fractions (NH₄Cl-RP, BD-RP, NaOH-NRP) formed 301 kg in upper 10 cm thick sediment layer of hypolimnetic bottom sediment (40% of lake bottom area).     

磷模型在千岛湖水体污染预测中的应用研究

运用国际上通用的多个经验统计磷模型预测千岛湖目前的磷浓度水平,其中第6个模型最适合用于千岛湖的预测预报．利用该模型预测了磷负荷量分别减少1/4、1/2、3/4情况下,千岛湖水体中总磷浓度的响应．同时针对千岛湖营养水平控制的短、长期目标,利用模型计算出了所允许的总磷负荷量及入湖磷浓度．     

Organochlorine Pesticides in Sediments around Chaohu Lake: Concentration Levels and Vertical Distribution

Eighteen organochlorine pesticides (OCPs) were investigated in surface sediments from the Nanfei River and in four sediment cores from the primary estuaries of Chaohu Lake, Eastern China. The results indicate that the OCP concentrations in the surface and core sediments around Chaohu Lake were 3.48–121.08 (with a mean of 34.93) ng/g and 0.60–39.28 (7.07) ng/g, respectively. Significantly higher concentrations of ΣOCPs were observed in sediment samples from the Nanfei River and its estuary. The three important OCP contributors around Chaohu Lake were dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB), which originated primarily from the historical use of technical DDTs and HCHs. A principal component analysis (PCA) suggests that HCB and lindane may originate from the same sources, and DDTs were greatly influenced by organic carbon from the soil environment and the impact of urbanization processes.     

鄱阳湖流域含珍稀针叶树种的群落特征

亚热带分布有众多珍稀针叶树种, 珍稀针叶植物的保护与濒危机制研究受到广泛关注。为了解鄱阳湖流域天然森林植被中珍稀针叶树种的分布及其生存状况, 对其所在的植物群落进行调查。调查采用样方法, 样方面积20 m × 20 m, 记录样方信息、群落物种组成及数量特征, 计算物种重要值, 分析了群落的类型及结构特征。样方分布于鄱阳湖流域内南岭山地、罗宵山脉、武夷山脉、黄山山脉、九岭山脉。论文提供了23组详细的群落样方数据, 11种珍稀针叶树种分布于14个不同群系中, 珍稀针叶植物多以共建种或伴生种出现在群落中, 以针叶树为优势种的群系有南方红豆杉(Taxus wallichiana var. mairei)林、黄杉(Pseudotsuga sinensis)林、福建柏(Fokienia hodginsii)林、榧树(Torreya grandis)林。     

Characteristics of plant communities containing rare conifers in Poyang Lake Basin,China

The endangerment mechanism of rare conifer species is a very critical problem in conservation biodiversity. Thus, the studies on the protection of the rare and endangered coniferous trees have received extensive attention. The objective of this study was to understand the survival and distribution of the rare coniferous tree species in natural forests of the Poyang Lake Basin. Field investigations on plant communities were conducted in 21 plots from Oct. 2014 to Oct. 2015. These plots were distributed in the Nanling Mountains, Luoxiao Mountains, Wuyi Mountains, Huangshan Mountains, and Jiuling Mountain. The dimensions of each plot were 20 m × 20 m. Community species composition and quantitative characteristics in each plot were recorded. The importance values of trees, shrubs and herbs were computed, respectively. The community types and structural properties were analyzed. A total of 23 sets of community sampling data were obtained in details. A number of 11 species of rare conifers were found in 14 different formations. Rare conifer trees mainly occurred in the communities as co-edificatos or companion species. The formations included Form. Taxus wallichiana var. mairei, Form. Pseudotsuga sinensis, Form. Fokienia hodginsii and Form. Torreya grandis, where the dominant species was coniferous trees. In conclusion, our study provides valuable field investigation data of rare coniferous in Poyang Lake basin, which could provide insight into the protection and management of these species.