三种城市不透水地表沉积物采样装置应用比较

采用3种采样装置对不透水地表沉积物进行采样分析和比较。结果发现:单位面积SS累积采集量大小顺序为水洗采样装置、真空采样装置、框架采样装置;颗粒物样品中常规污染物总量大小顺序同样为水洗采样装置、真空采样装置、框架采样装置,但单位SS中常规污染物含量大小顺序为框架采样装置、真空采样装置、水洗采样装置,表明常规污染物大都存在于易于收集的地表颗粒物中。3种采样装置便携程度为框架采样装置、真空采样装置和水洗采样装置。实际应用时可依据采样距离、采样点地表性质和沉积物累积程度、样品保存和测定时限要求等情况选择不同的采样装置。     

Comparative spatial metal concentrations and partitioning in bottom sediments of two tropical freshwater lake basins,Kenya

Metal concentrations in the water, sediments and biota in alkaline, near neutral water tropical freshwater lake basins were determined and a comparative analysis made on the spatial and accumulated trace metal concentrations, and geochemical partitioning of iron (Fe), manganese (Mn), copper (Cu), chromium (Cr), zinc (Zn), nickel (Ni), cadmium (Cd) and lead (Pb) in bottom lake sediments. Variable accumulated levels were found in the analysed sediments and aquatic biological tissues. Metal partitioning data in the present study from the two areas exhibits similar trends in magnitude. The residual fractions retained relatively higher amounts of metals. Relatively higher contents of Pb, Cr and Cu were found in Lake Victoria sediments. Cd, Ni, Mn and Pb are of concern because a higher percentage of these metals were retained in the more bioavailable fractions in Lake Naivasha. Total levels of sediment mercury were comparable for the two lake basins. Metals were found in significant levels in the tissues of aquatic organisms, highlighting the potential risks to other levels within the aquatic food chain. Although the exposure risk was not evaluated, it is important to continue monitoring these elements in fish, as sediments were found to contain considerable quantities of the metals. Numerous sediment extraction techniques data applied for evaluating metal partitioning in sediments cannot be compared because of the use of different methods. Nevertheless, the information is still useful in differentiating and understanding pollution loads from natural versus anthropogenic sources and their associated risks.     

Vertical Distribution of Profundal Benthos in Lake Superior Sediments

Layers of sediment in box cores from 10 Lake Superior open lake sites were sieved at 250 μm to retain benthos. The average density of benthic organisms, 3,055/m², was higher than has previously been reported for profundal regions of the lake, suggesting that biological mixing is important in the sediments. Bottom fauna were distributed from the water-sediment interface to a depth of 1.7 cm in firm glacial till and to a depth of 15 cm in soft clay. There was variability between sampling sites: oligochaetes and nematodes penetrated further into loose sediments than into compacted sand or clay. Ninety-six percent of the profundal benthos was found within the first four centimeters of sediment, with 47% between 0 and 0.5 cm (mostly Pontoporeia hoyi, naidids, sphaeriids, copepods, ostracods, and neorhabdocoels); 49% between 0.5 and 4 cm (mostly nematodes and oligochaetes); and 4% below 4 cm. The location of oligochaete cocoons containing embryos indicated that enchytraeid positions in the cores often represented their in situ vertical distribution, whereas some of the lumbriculids and tubificids migrated downward during the sampling procedures. The density and vertical distribution of Pontoporeia indicated that the potential depth and rate of biological mixing of sediment may exceed the sediment accumulation rate in Lake Superior.     

泥沙筛析与沉降粒径关系及其应用的研究

为准确测定泥沙的沉降粒径并确定筛析粒径与Ｄ沉的关系，试验中采用天然沙的筛析分组沙作为试样，逐颗测定沉积，得出Ｄ沉以及Ｄ筛与Ｄ沉的关系。经分析论证并与国际上的试验塑料比较后认为，试验所得Ｄ筛与Ｄ沉关系合理可靠。     

Spatial variations in sedimentary organic matter in surficial lake sediments of Nyanza Gulf (Lake Victoria,Kenya) after invasion of water hyacinth

No detailed studies have been conducted on the spatial distribution of sediment characteristics within Nyanza Gulf of Lake Victoria, especially after the invasion of water hyacinth. Accordingly, a rapid, inexpensive method was used to determine the spatial sediment organic matter variations, expressed as loss on ignition (LOI). Surficial sediments were collected during different survey periods from about thirty‐two sampling sites between 1994 and 2012, in order to characterize the sediments. Although the deeper (>40 m) depositional areas are located in the open lake, visual observations indicate that most of the offshore sediments consist of muddy deposits, plus significant shell remains, with a more sandy type of sediments located in some areas off the inflowing river mouths. The surficial sediments were characterized by a relatively high water content, with over 89% of the samples containing water contents greater than 75%. The sediment organic matter contents from the 2012 survey were more variable, ranging from 1.90% to 33.47%. The sediment organic carbon contents varied spatially, although there were no significant variations between the different sampling periods. Evaluating the SOM at different heating durations at a constant temperature (550 °C) and a very high temperatures (950 °C) did not identify any significant differences. High primary production and greater settling in the deeper areas contribute to the nature of sediments deposited, also being reflected in the relatively high OC contents. Spatially, it is thought that detritus from water hyacinth and terrestrial external loads are important sources of organic matter deposited on the lake bottom within the gulf and may support its growth because of enrichment of nutrient elements. The importance of sediments in adsorption of contaminant substances and influencing geochemical processes within the lake is also emphasized.     

Distribution and geochemical processes of boron in the multimedia of Lake Qinghai,China

Lake Qinghai on the Qinghai-Tibet plateau is the largest lake in China. This study investigated the concentration and geochemical processes of boron (B) in lake water, lake sediment and river samples collected from Lake Qinghai and the Buha River. In addition, lake sediment pore water samples were analyzed. The concentrations of B and major ions, including K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^? and SO₄^2?, were analyzed in all the water samples. The average concentration of B was 0.07?mg?L^?1, 6.37?mg?L^?1, 12.79) mg?L^?1 and 59.42?mg?kg^?1 for river water, lake water, pore water, and sediment, respectively. There were significant (p?<?0.05) and positive (r?=?0.70) relationships between the B concentrations in bottom water of the lake and in lake sediment, indicating that B diffusion from the sediment plays an important role in the concentration of B in bottom lake water. The differences in B concentrations and B/major ion molar ratios of the river water, lake water, and pore water indicated the following geochemical processes: 1) B is enriched in the lake water through evaporative concentration; 2) B is removed from the lake water through mineral precipitation as well as sorption onto colloids; 3) Solid-phase B in sediments was released through dissolution driven by organic matter mineralization. B/Cl and Na/Cl molar ratios alone are not enough to identify the sources of B in the water of inland closed-basin saline lakes because of these processes.     

Diporeia site preference in Lake Superior: Food or physical factors?

Vital to the Lake Superior food web, the amphipod Diporeia remains the dominant macroinvertebrate in Lake Superior despite drastic population declines throughout the rest of the Laurentian Great Lakes. Diporeia is most abundant in the slope region of the lake at water depths between 30 and 125 m. It has been hypothesized that this depth range is preferred because of elevated primary production and deposition within this zone. This hypothesis of food driving habitat preference has not been directly tested. Here we used 120-hour preference-avoidance trials to record Diporeia choice of sediments from different water depths, seasons, and other treatments. Most preferences were weak to absent; however, Diporeia strongly preferred sediment from 30- and 60-m water depths over deeper or shallower sites. Contrary to the hypothesis about food driving habitat choice, chemical characteristics did not explain this strong preference. Grain size variation was the only measured variable that was consistent between the sites preferred by Diporeia and different from unpreferred sites. Both the 30- and 60-meter sites contained predominantly medium silt but had a wider range in grain sizes. These results indicate that physical habitat characteristics may have a stronger bearing on Diporeia habitat preference than food availability and may account for their distribution in the lake. The results also may imply that the role of dreissenid mussels as ecosystem engineers altering sediment physical characteristics may be important where they are abundant.     

The seasonal and spatial variations of labile copper, iron, manganese, lead and zinc sediment fractions in Lake Naivasha, Kenya

Lake Naivasha is a freshwater lake with no surface outlet, lying within a closed basin of the Kenyan Rift Valley. It is perceived to be a lake undergoing anthropogenic stresses. This study is intended to determine the speciation of some selected heavy metals in the sediments of Lake Naivasha, as an indicator of potential pollution of the lake. Sediment and water sampling of the lake was conducted in March and May 2003, during the dry and wet seasons, respectively. Analyses of the speciation of heavy metals in sediment samples (<63 µm faction) were performed on sediment samples collected from five sites within the lake. The study results obtained indicated that influent Malewa River was not a source of labile copper (Cu), lead (Pb) or zinc, despite the river having the highest percentage clay content during the wet season (86%). Copper was highly distributed in the residual sediment fraction (average of 90%). Among the labile sediment factions, the highest quantity of Cu was in the oxidizable phase (3.58 and 2.30 µg g⁻¹ during the dry and wet season, respectively). Carbonate‐bound Cu was sparingly distributed during both the dry and the wet seasons, ranging between 0.74 and 1.81 µg g⁻¹. Iron was highly distributed in the oxidizable sediment phase, exhibiting concentrations ranging between 2.0 and 6.0 (×10³) µg g⁻¹. Relative to the other heavy metals, manganese was distributed in lower proportions in the residual sediment fraction. High concentrations of Pb were observed in the oxidizable phase from most of the sampling sites along the lake shore. Zinc was distributed largely in the oxidizable phase, being highest at sampling site SS, which was located near a municipal sewage input to the lake. The sediments collected at the sampling sites located in the deep portion of the lake exhibited the highest concentrations of labile heavy metals.     

图像处理技术在泥沙粒径分析中的应用

基于数字图像处理技术的泥沙粒径分析是近年发展起来的一种新方法。传统分水岭分割方法直接作用于梯度图像,受图像噪声、目标的细小边缘及纹理等因素影响,测量精度会相对降低。通过标记重构和区域合并对传统分水岭分割法进行优化,提出改进算法。基于实测数据,围绕数字图像处理相关技术,借鉴其他领域图像分析设备和方法,以数码单反相机和Image J2x图像处理软件为基础,建立一套泥沙图像粒径分析系统。采用图像法、机械筛分法和激光分析法分别对同一批沙样进行粒径测定。对测定结果进行的分析表明数字图像处理技术可较好地用于泥沙粒径分析。     

鄱阳湖现代冲淤动态分析

通过对鄱阳湖现代动力分析,分析了鄱阳湖物质来源主要是五河带来的泥沙为主,水流是输沙的主要动力,叙述了五河入湖口扩散区、湖体冲淤动态。     

Fractioning of petroleum hydrocarbons from seeped oil as a factor of purity preservation of water in Lake Baikal (Russia)

Polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were found in five different types of oil-containing samples emanating from deep oil seeps in Lake Baikal, the deepest and oldest lake in the world containing 20% of the world’s surface freshwater. The n-alkanes were the dominant component of the seeped oil on the water surface. PAHs were minor compounds of the oil, but this group is included in a priority series of organic contaminants that are subject to environmental regulation. The set of studied samples from the seep included: (i) freshly-emitted oil on the lake surface, (ii) oil at the lake bottom, (iii) samples of asphalt towers at the lake bottom, (iv) oil from voids within the sediment core and (v) samples of water from different depths. High variability in the concentrations of n-alkanes and PAHs suggested the presence of oil fractionation at the sediment-water interface. A light fraction of oil enriched by n-alkanes migrates to the surface of the lake’s water column, where n-alkanes are biodegraded by the Baikal microbial community while heavy oil fractions remain at the lake bottom and form asphalt towers in which PAHs with maximum toxicity accumulate. In the lake’s photic water layer, PAHs from light oil can be accumulated by phytoplankton. In the lake’s water column, benzo[a]pyrene was not detected over their detection limit (0.1 ng/L). The Toxic Equivalent (TEQ) value of PAHs identified in the Baikal water ranged from 0.001 to 0.012 ng/L.     

Ecotoxicological risks from dissolved organic contaminants in a contaminated bay: Combining passive sampling with in vivo bioassays

Innovative and robust methods are needed to evaluate the risks to native aquatic organisms exposed to organic compounds released from contaminated sediments. In the present study, we deployed semi-permeable membrane devices (SPMDs) above sediments in a contaminated harbor at a location in the Laurentian Great Lakes (i.e. Owen Sound Bay) and prepared extracts from these passive samplers for analysis of organic contaminants and for toxicity testing using early life stages of Japanese medaka (Oryzias latipes) and lake whitefish (Coregonus clupeaformis). The concentrations of several classes of organic contaminants estimated from analysis of the SPMD extracts indicated that several polynuclear aromatic hydrocarbon (PAHs) were present in the water column in the inner harbor of Owen Sound Bay at concentrations higher than water quality standards for the protection of aquatic life. Several medaka exposed to the SPMD extract from the inner harbor as well as a positive control compound, benzo[a]pyrene, developed yolk sac edema. However, whitefish did not show the same response. Overall, these data indicate this contamination could contribute to toxicity in sensitive species. The coupling of passive sampling and in vivo bioassays with early life stages of fish shows promise as a method to assess the potential for risks from biologically available fractions of organic contaminants in water. A novel aspect of the present study is the development of a bioassay procedure with early life stages of lake whitefish involving exposures at low temperatures over durations of time that are longer than the bioassays with more conventional model fish species.     

沙漠沙的筛分粒径与粒径计粒径的比较实验

筛分法与粒径计法是两种重要的颗粒分析方法。本文通过较为系统的实验发现采用这两种方法所得到的实验结果之间存在较大的偏差。采用粒径计法测得的样品粒径较之用筛分法所得的结果明显偏大 ,说明用这两种原理不同的颗分方法所测出的粒径数据不能不加换算地直接采用。由于目前有关筛分粒径与粒径计粒径转换关系的研究结果并不一致 ,所以文中比较了几家代表性研究成果之间的差异 ,重点讨论了采用不同沉降速度公式进行计算时所得粒径计粒径之间的差异 ,探讨了各家结果不同的原因 ,对与颗粒粒径相关的研究具有参考价值     

A case study of water retention and ecosystem functioning restoration in Wenying Lake (China)

Wenying Lake in Datong, China, has been drying for the last several years. Analysis of standard penetration test data revealed that a missing waterproof layer of silt soil and silty clay in the south part of the lake, resulting from frequent flood flushing, was responsible for the water loss from the lake. Accordingly, 6.7 × 10⁵ m² of geosynthetic clay liner (GCL) was used in May 2010 to repair the area of sediment exhibiting the water leakage, equivalent to 15.6% of the total lake bottom area. Approximately 4.1 × 10⁶ m³ of floodwater was then diverted from upstream rivers to the lake. Eight months later, about 0.9 × 10⁶ m³ of the water was retained, with the water loss being reduced from 4.0 to 1.1 m³ m^?2 year^?1. Ecologically safe and cost‐effective clay materials also can be used to furthermore improve the water retention characteristics. Modelling results indicated that capping the whole lake with a 2 cm layer of bentonite with a permeability coefficient of 5.0 × 10^?9 cm s^?1 could reduce the sediment water leakage to 0.04 m³ m^?2 year^?1. The quality of the retained water after GCL treatment project was poor, with a total nitrogen concentration of 11.0 mg L^?1 and sulphate 307.0 mg L^?1, which were 5 and 300 times higher, respectively, than the Chinese class V surface water standard. Restoration of aquatic vegetation in the lake and constructed wetlands near the lake inlets could be helpful to improve the lake’s water quality over the long term.     

阳宗海砷污染水质变化过程分析

为掌握2008年阳宗海砷（As）污染事件后控制与修复过程中水质特征及变化,对湖水As含量、pH值、电导率、总硬度等水质参数,以及底质As含量和生物残毒进行全程监测和分析评价。结果表明：阳宗海As污染事件后水质恢复历时28个月;阳宗海湖水As质量浓度经历了先上下波动、后持续下降再到稳定在0．05mg／L以下的变化过程;底泥中As的质量浓度经历了先迅速升高后大幅下降,再小幅上涨后又回落至21．5～27．0mg／L的变化过程;pH值、电导率及总硬度等参数受到一定影响,湖水中贝类等水生生物对As的富集能力较强。最后从管理角度提出了保护阳宗海水资源的措施。     

湖泊底泥絮凝沉降试验研究

湖泊底泥的运动过程产生了内源污染,加剧了湖泊生态环境的恶化。研究湖泊底泥在风浪作用下悬浮后再沉降的运移规律,可为了解湖泊水质变化成因以及开展生态环境治理提供技术支持。本课题采用有机玻璃制作的沉降桶,在静水条件下对太湖、龙感湖、巢湖的底泥进行了沉降试验,研究3个湖泊的水体在不同初始含沙浓度和不同水深条件下含沙浓度的变化,分析了3个湖泊淤泥的沉降规律,近似代表天然湖泊的底泥运动状态。试验研究表明3个湖泊水体中悬浮泥沙的沉降均为絮凝沉降,其沉降过程和沉速与单颗粒泥沙相比均发生了量和质的变化,悬浮泥沙絮凝平均沉速随沉距、含沙浓度的增大而增大。最后得出3个湖泊底泥的沉降速度,其研究结果可为采用絮凝沉降法改善水质环境提供参考依据。     

淮河中游河道与洪泽湖水沙交换程度分析

淮河中游河道与洪泽湖的水沙交换程度影响着河湖之间的内在关系,通过计算淮河与洪泽湖1975-2015年的水沙交换指数,利用多种统计检验交叉互补的方法,对河湖水量交换指数和泥沙交换指数进行了趋势变化、突变检验及周期性分析。结果表明：受不同年代治淮工程的影响,河湖水量交换指数整体而言呈不显著增大趋势,造成洪泽湖库容呈不显著增大趋势;入湖泥沙量大于出湖泥沙量,湖盆泥沙的淤积量逐年呈不显著增大趋势。洪泽湖库容及湖盆淤积在研究时期内呈稳定的波动状态,未发生较为显著的突变现象。淮河干流与洪泽湖的水沙交换程度存在多时间尺度的周期性特征,均以14a为第一主周期,河湖水沙交换程度处于相对稳定的状态。研究结果阐明了淮河中游河道与洪泽湖的水沙作用关系,可为河湖治理提供理论参考。     

基于实测数据的鄱阳湖悬浮泥沙粒度遥感反演模式分析

水体悬浮泥沙粒度是重要的水质参数之一,影响着水体的遥感反射率。研究两者之间的关系对于内陆湖泊水环境遥感监测具有重要意义。基于鄱阳湖实测数据,采用相关分析方法,用不同数学模型进行鄱阳湖悬浮泥沙粒度反演研究。研究结果表明:(1)浑浊区适合采用体积百分比众数粒径建立反演模型,清水区适合采用数量百分比中值粒径建立反演模型;(2)浑浊区悬沙粒度的敏感单波段是环境卫星Ⅳ波段,在清水区悬沙粒度的敏感单波段有环境卫星Ⅱ和Ⅲ波段,而环境卫星Ⅱ,Ⅲ波段比组合是整个研究区水域的敏感波段;(3)单波段反演模型中,幂函数适用于鄱阳湖粒度遥感反演;波段比反演模型中,多项式模型适于鄱阳湖粒度遥感反演。     

Circular Rep encoding single stranded (CRESS) DNA virus-like sequences detected in quagga mussels (Dreissena rostriformis bugensis) and sediments from the central Lake Michigan benthos

Circular Rep Encoding Single Stranded (CRESS) DNA viruses are a diverse group of viruses that have been identified in both terrestrial and aquatic ecosystems. Recent work in the Laurentian Great Lakes characterized the ecology and diversity of CRESS-DNA viruses associated with amphipods, Diporeia spp. In the last 20 years the Lake Michigan benthos has changed considerably with drastic population declines of Diporeia spp. concurrent with an increase in invasive quagga mussel (Dreissena rostriformis bugensis) abundance. The purpose of this study was to characterize CRESS-DNA virus-like elements (VLES; which could represent complete, partial/defective, endogenized or satellite viruses) associated with both invasive quagga mussels and in sediment collected in central Lake Michigan. Viral metagenomic libraries were prepared from two size classes (>25 mm and <15 mm shell length) of Lake Michigan quagga mussels and for two different sediment layers (136 mm and 290 mm below the lake floor) in a sediment core extracted from the lake. Viral metagenomes were different between quagga mussels and sediment cores. Nine VLE sequences were present in both the quagga mussel tissues and the sediment core layers analyzed. Cs¹³⁷ radiometric dating results indicate that these VLEs were present in the sediment prior to arrival of quagga mussels in Lake Michigan. These data suggest quagga mussels may interact with CRESS-DNA VLEs and algal DNA VLEs historically present in the Lake Michigan benthos. Overall, these data suggest that quagga mussels interacted with CRESS-DNA VLES present in Lake Michigan benthos since at least 1952.     

Benthic video image analysis facilitates monitoring of Dreissena populations across spatial scales

In contrast to marine systems where remote sensing methods in studies of benthic organisms have been widely used for decades, these methods have experienced limited use in studies of freshwater benthos due to the general lack of large epifauna. The situation has changed with the introduction of dreissenid bivalves capable of creating visible aggregations on lake bottoms into North American freshwaters in the 1980s and 1990s. The need for assessment of Dreissena densities prompted exploration of videography as a potentially cost-effective tool. We developed a novel sampling method that analyzes video recorded using a GoPro camera mounted to a benthic sled to estimate Dreissena coverage, density, and biomass over relatively large areas of the lake bed in the Laurentian Great Lakes compared to traditional sampling methods. Using this method, we compared quagga mussel coverage, density, and biomass estimates based on three replicate Ponar grabs vs. 500?m-long video transects across 43 stations sampled in Lake Michigan in 2015. Our results showed that analysis of images from video transects dramatically increased the bottom area surveyed compared to Ponar grabs and increased the precision of Dreissena density and biomass estimations at monitoring stations. By substantially increasing the ability to detect relatively small (<20%) changes between years within a particular station, this method could be a useful and cost-effective addition for monitoring Dreissena populations in the Great Lakes and other freshwater systems where they occur.